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The e-newsletter Marine Science Review compiles citations and abstracts of significant marine-related research, selected from more than 710 science journals. Each of its 12 subject areas, which include the range of important issues involving the intersection of human activity with coastal and marine environments, is distributed monthly. You can subscribe to each subject area individually or to all.

October 13, 2011

Marine Fauna and Flora: Marine Mammals

Reviews

  • Bossart, G.D.  Marine mammals as sentinel species for oceans and human health.  Veterinary Pathology 48(3): 676-690, 2011.
    Read Abstract >>

    The long-term consequences of climate change and potential environmental degradation are likely to include aspects of disease emergence in marine plants and animals. In turn, these emerging diseases may have epizootic potential, zoonotic implications, and a complex pathogenesis involving other cofactors such as anthropogenic contaminant burden, genetics, and immunologic dysfunction. The concept of marine sentinel organisms provides one approach to evaluating aquatic ecosystem health. Such sentinels are barometers for current or potential negative impacts on individual- and population-level animal health. In turn, using marine sentinels permits better characterization and management of impacts that ultimately affect animal and human health associated with the oceans. Marine mammals are prime sentinel species because many species have long life spans, are long-term coastal residents, feed at a high trophic level, and have unique fat stores that can serve as depots for anthropogenic toxins. Marine mammals may be exposed to environmental stressors such as chemical pollutants, harmful algal biotoxins, and emerging or resurging pathogens. Since many marine mammal species share the coastal environment with humans and consume the same food, they also may serve as effective sentinels for public health problems. Finally, marine mammals are charismatic megafauna that typically stimulate an exaggerated human behavioral response and are thus more likely to be observed.

  • Pompa, S., Ehrlich, P.R., and Ceballos, G.  Global distribution and conservation of marine mammals.  Proceedings of the National Academy of Sciences 108(33): 13600-13605, 2011.
    Read Abstract >>

    We identified 20 global key conservation sites for all marine (123) and freshwater (6) mammal species based on their geographic ranges. We created geographic range maps for all 129 species and a Geographic Information System database for a 46,184 1º x 1º grid-cells, ~10,000-km2. Patterns of species richness, endemism, and risk were variable among all species and species groups. Interestingly, marine mammal species richness was correlated strongly with areas of human impact across the oceans. Key conservation sites in the global geographic grid were determined either by their species richness or by their irreplaceability or uniqueness, because of the presence of endemic species. Nine key conservation sites, comprising the 2.5% of the grid cells with the highest species richness, were found, mostly in temperate latitudes, and hold 84% of marine mammal species. In addition, we identified 11 irreplaceable key conservation sites, six of which were found in freshwater bodies and five in marine regions. These key conservation sites represent critical areas of conservation value at a global level and can serve as a first step for adopting global strategies with explicit geographic conservation targets for Marine Protected Areas.

  • Kovacs, K.M., Lydersen, C., Overland, J.E., and Moore, S.E.  Impacts of changing sea-ice conditions on Arctic marine mammals.  Marine Biodiversity 41(1): 181-194, 2011.
    Open Access >>
    Read Abstract >>

    Arctic sea ice has changed dramatically, especially during the last decade and continued declines in extent and thickness are expected for the decades to come.  Some ice-associated marine mammals are already showing distribution shifts, compromised body condition and declines in production/abundance in response to sea-ice declines. In contrast, temperate marine mammal species are showing northward expansions of their ranges, which are likely to cause competitive pressure on some endemic Arctic species, as well as putting them at greater risk of predation, disease and parasite infections. The negative impacts observed to date within Arctic marine mammal populations are expected to continue and perhaps escalate over the coming decade, with continued declines in seasonal coverage of sea ice. This situation presents a significant risk to marine biodiversity among endemic Arctic marine mammals.

Sea Otters

  • Miller, M.A., Conrad, P.A., Harris, M., Hatfield, B., Langlois, G., Jessup, D.A., Magargal, S.L., Packham, A.E., Toy-Choutka, S., Melli, A.C., Murray, M.A., Gulland, F.M., and Grigg, M.E.  A protozoal-associated epizootic impacting marine wildlife: Mass-mortality of southern sea otters (Enhydra lutris nereis) due to Sarcocystis neurona infection.  Veterinary Parasitology 172(3-4): 183-194, 2010. 
    Read Abstract >>

    During April 2004, 40 sick and dead southern sea otters (Enhydra lutris nereis) were recovered over 18 km of coastline near Morro Bay, California. This event represented the single largest monthly spike in mortality ever recorded during 30 years of southern sea otter stranding data collection. Because of the point-source nature of the event and clinical signs consistent with severe, acute neurological disease, exposure to a chemical or marine toxin was initially considered. However, detailed postmortem examinations revealed lesions consistent with an infectious etiology, and further investigation confirmed the protozoan parasite Sarcocystis neurona as the underlying cause. Tissues from 94% of examined otters were PCR-positive for S. neurona, based on DNA amplification and sequencing at the ITS-1 locus, and 100% of tested animals (n = 14) had elevated IgM and IgG titers to S. neurona. Evidence to support the point-source character of this event include the striking spatial and temporal clustering of cases and detection of high concentrations of anti-S. neurona IgM in serum of stranded animals. Concurrent exposure to the marine biotoxin domoic acid may have enhanced susceptibility of affected otters to S. neurona and exacerbated the neurological signs exhibited by stranded animals. Other factors that may have contributed to the severity of this epizootic include a large rainstorm that preceded the event and an abundance of razor clams near local beaches, attracting numerous otters close to shore within the affected area. This is the first report of a localized epizootic in marine wildlife caused by apicomplexan protozoa.

  • Miller, M.A. et alEvidence for a novel marine harmful algal bloom: Cyanotoxin (microcystin) transfer from land to sea otters.  PLoS ONE 5(9): art. e12576, 2010.
    Open Access >>  
    Read Abstract >>

    "Super-blooms" of cyanobacteria that produce potent and environmentally persistent biotoxins (microcystins) are an emerging global health issue in freshwater habitats. Monitoring of the marine environment for secondary impacts has been minimal, although microcystin-contaminated freshwater is known to be entering marine ecosystems. Here we confirm deaths of marine mammals from microcystin intoxication and provide evidence implicating land-sea flow with trophic transfer through marine invertebrates as the most likely route of exposure. This hypothesis was evaluated through environmental detection of potential freshwater and marine microcystin sources, sea otter necropsy with biochemical analysis of tissues and evaluation of bioaccumulation of freshwater microcystins by marine invertebrates. Ocean discharge of freshwater microcystins was confirmed for three nutrient-impaired rivers flowing into the Monterey Bay National Marine Sanctuary, and microcystin concentrations up to 2,900 ppm (2.9 million ppb) were detected in a freshwater lake and downstream tributaries to within 1 km of the ocean. Deaths of 21 southern sea otters, a federally listed threatened species, were linked to microcystin intoxication. Finally, farmed and free-living marine clams, mussels and oysters of species that are often consumed by sea otters and humans exhibited significant biomagnification (to 107 times ambient water levels) and slow depuration of freshwater cyanotoxins, suggesting a potentially serious environmental and public health threat that extends from the lowest trophic levels of nutrient-impaired freshwater habitat to apex marine predators. Microcystin-poisoned sea otters were commonly recovered near river mouths and harbors and contaminated marine bivalves were implicated as the most likely source of this potent hepatotoxin for wild otters. This is the first report of deaths of marine mammals due to cyanotoxins and confirms the existence of a novel class of marine "harmful algal bloom" in the Pacific coastal environment; that of hepatotoxic shellfish poisoning (HSP), suggesting that animals and humans are at risk from microcystin poisoning when consuming shellfish harvested at the land-sea interface.

  • Hatfield, B.B., Ames, J.A., Estes, J.A., Tinker, M.T., Johnson, A.B., Staedler, M.M., and Harris, M.D.  Sea otter mortality in fish and shellfish traps: estimating potential impacts and exploring possible solutions.  Endangered Species Research 13(3): 219-229, 2011.
    Open Access >>  
    Read Abstract >>

    Sea otters Enhydra lutris can be bycaught and drowned in fishing pots and traps, which may pose a threat to the welfare of otter populations. We explored this potential problem and its solutions using a wide variety of analyses. We exposed live California (USA) sea otters to finfish traps, lobster traps, and mock Dungeness crab traps in captive trials and found that the animals attempted to enter the circular and rectangular fyke openings, with some becoming entrapped. Using both live and dead sea otters, we found that a 3 × 9 inch (7.6 × 22.9 cm) fyke opening (1 inch narrower than the 4 × 9 inch [10.2 × 22.9 cm] openings currently used in California's commercial Dungeness crab fishery) would exclude most free-living (i.e. weaned from their mothers) otters while permitting the undiminished capture of crabs. Observer programs do not currently exist in California for these fisheries, so we calculated the effort required by an observer program to document sea otter bycatch over a range of hypothetical levels and evaluated the impact of those mortality rates on population growth. These analyses demonstrate that significant mortality from bycatch might easily go undetected, even with seemingly high levels of observer effort. As sea otters reoccupy portions of their former habitat in California, co-occurrence with finfish and shellfish traps with relatively large fyke openings will increase.

Polar Bears

  • Rode, K.D., Amstrup, S.C., and Regehr, E.V.  Reduced body size and cub recruitment in polar bears associated with sea ice decline.  Ecological Applications 20(3): 768-782, 2010. 
    Read Abstract >>

    Rates of reproduction and survival are dependent upon adequate body size and condition of individuals. Declines in size and condition have provided early indicators of population decline in polar bears (Ursus maritimus) near the southern extreme of their range. We tested whether patterns in body size, condition, and cub recruitment of polar bears in the southern Beaufort Sea of Alaska were related to the availability of preferred sea ice habitats and whether these measures and habitat availability exhibited trends over time, between 1982 and 2006. The mean skull size and body length of all polar bears over three years of age declined over time, corresponding with long-term declines in the spatial and temporal availability of sea ice habitat. Body size of young, growing bears declined over time and was smaller after years when sea ice availability was reduced. Reduced litter mass and numbers of yearlings per female following years with lower availability of optimal sea ice habitat, suggest reduced reproductive output and juvenile survival. These results, based on analysis of a long-term data set, suggest that declining sea ice is associated with nutritional limitations that reduced body size and reproduction in this population.

  • Stirling, I., McDonald, T.L., Richardson, E.S., Regehr, E.V., and Amstrup, S.C.  Polar bear population status in the northern Beaufort Sea, Canada, 1971-2006.  Ecological Applications 21(3): 859-876, 2011. 
    Read Abstract >>

    Polar bears (Ursus maritimus) of the northern Beaufort Sea (NB) population occur on the perimeter of the polar basin adjacent to the northwestern islands of the Canadian Arctic Archipelago. Sea ice converges on the islands through most of the year. We used open population capture-recapture models to estimate population size and vital rates of polar bears between 1971 and 2006 to: (1) assess relationships between survival, sex and age, and time period; (2) evaluate the long-term importance of sea ice quality and availability in relation to climate warming; and (3) note future management and conservation concerns. The highestranking models suggested that survival of polar bears varied by age class and with changes in the sea ice habitat. Model-averaged estimates of survival (which include harvest mortality) for senescent adults ranged from 0.37 to 0.62, from 0.22 to 0.68 for cubs of the year (COY) and yearlings, and from 0.77 to 0.92 for 2-4 year-olds and adults. Horvtiz-Thompson (HT) estimates of population size were not significantly different among the decades of our study. The population size estimated for the 2000s was 980 ± 155 (mean and 95% CI). These estimates apply primarily to that segment of the NB population residing west and south of Banks Island. The NB polar bear population appears to have been stable or possibly increasing slightly during the period of our study. This suggests that ice conditions have remained suitable and similar for feeding in summer and fall during most years and that the traditional and legal Inuvialuit harvest has not exceeded sustainable levels. However, the amount of ice remaining in the study area at the end of summer, and the proportion that continues to lie over the biologically productive continental shelf (<300 m water depth) has declined over the 35-year period of this study. If the climate continues to warm as predicted, we predict that the polar bear population in the northern Beaufort Sea will eventually decline. Management and conservation practices for polar bears in relation to both aboriginal harvesting and offshore industrial activity will need to adapt.

  • Rode, K.D., Reist, J.D., Peacock, E., and Stirling, I.  Comments in response to ''Estimating the energetic contribution of polar bear (Ursus maritimus) summer diets to the total energy budget'' by Dyck and Kebreab (2009).  Journal of Mammalogy 91(6): 1517-1523, 2010. 
    Read Abstract >>

    Dyck and Kebreab (2009) analyzed the required summer intake of arctic char, ringed seal blubber, and berries that polar bears must consume to maintain their body mass during a summer ice-free period. Their calculations of required intake were based on the amount of body mass lost by fasting bears in western Hudson Bay. However, fasting polar bears are in a low metabolic state with energetic requirements less than those of an active, feeding bear. Estimates of energy consumed by captive brown bears were 4 - 4.5 times higher than the estimates used by Dyck and Kebreab for similar diets. Furthermore, the authors' portrayal of the availability of these resources is misleading because they do not acknowledge limited accessibility of arctic char due to their limited anadromy and predominant occurrence in streams too deep to facilitate efficient capture by polar bears; effects of large interannual fluctuations in the availability of berries or competition with other frugivores; high energetic requirements associated with lengthy foraging times required to locate and consume sufficient fruit; and data from southern Hudson Bay, western Hudson Bay, and the southern Beaufort Sea that document continued declines in several biological indices over the past several decades despite the authors' suggested availability of terrestrially based food resources. Based on current information, arctic char, berries, and ringed seals in open water do not appear to be food sources with the potential to offset the nutritional consequences of an extended ice-free period.

  • Hunter, C.M., Caswell, H., Runge, M.C., Regehr, E.V., Amstrup, S.C., and Stirling, I.  Climate change threatens polar bear populations: a stochastic demographic analysis.  Ecology 91(10): 2883-2897, 2010. 
    Read Abstract >>

    The polar bear (Ursus maritimus) depends on sea ice for feeding, breeding, and movement. Significant reductions in Arctic sea ice are forecast to continue because of climate warming. We evaluated the impacts of climate change on polar bears in the southern Beaufort Sea by means of a demographic analysis, combining deterministic, stochastic, environment-dependent matrix population models with forecasts of future sea ice conditions from IPCC general circulation models (GCMs). The matrix population models classified individuals by age and breeding status; mothers and dependent cubs were treated as units. Parameter estimates were obtained from a capture-recapture study conducted from 2001 to 2006. Candidate statistical models allowed vital rates to vary with time and as functions of a sea ice covariate. Model averaging was used to produce the vital rate estimates, and a parametric bootstrap procedure was used to quantify model selection and parameter estimation uncertainty. Deterministic models projected population growth in years with more extensive ice coverage (2001-2003) and population decline in years with less ice coverage (2004-2005). LTRE (life table response experiment) analysis showed that the reduction in l in years with low sea ice was due primarily to reduced adult female survival, and secondarily to reduced breeding. A stochastic model with two environmental states, good and poor sea ice conditions, projected a declining stochastic growth rate, log λs, as the frequency of poor ice years increased. The observed frequency of poor ice years since 1979 would imply log λs ≈ –0.01, which agrees with available (albeit crude) observations of population size. The stochastic model was linked to a set of 10 GCMs compiled by the IPCC; the models were chosen for their ability to reproduce historical observations of sea ice and were forced with ''business as usual'' (A1B) greenhouse gas emissions. The resulting stochastic population projections showed drastic declines in the polar bear population by the end of the 21st century. These projections were instrumental in the decision to list the polar bear as a threatened species under the U. S. Endangered Species Act.

  • Kelly, B., Whiteley, A., and Tallmon, D.  The Arctic melting pot.  Nature 468(7326): 891, 2010. 
  • Derocher, A.E.  The prospects for polar bears.  Nature 468(7326): 905-906, 2010. 
  • Amstrup, S.C., DeWeaver, E.T., Douglas, D.C., Marcot, B.G., Durner, G.M., Bitz, C.M., and Bailey, D.A.  Greenhouse gas mitigation can reduce sea-ice loss and increase polar bear persistence.  Nature 468(7326): 955-U351, 2010. 
    Read Abstract >>

    On the basis of projected losses of their essential sea-ice habitats, a United States Geological Survey research team concluded in 2007 that two-thirds of the world's polar bears (Ursus maritimus) could disappear by mid-century if business-as-usual greenhouse gas emissions continue. That projection, however, did not consider the possible benefits of greenhouse gas mitigation. A key question is whether temperature increases lead to proportional losses of sea-ice habitat, or whether sea-ice cover crosses a tipping point and irreversibly collapses when temperature reaches a critical threshold. Such a tipping point would mean future greenhouse gas mitigation would confer no conservation benefits to polar bears. Here we show, using a general circulation model, that substantially more sea-ice habitat would be retained if greenhouse gas rise is mitigated. We also show, with Bayesian network model outcomes, that increased habitat retention under greenhouse gas mitigation means that polar bears could persist throughout the century in greater numbers and more areas than in the business-as-usual case. Our general circulation model outcomes did not reveal thresholds leading to irreversible loss of ice; instead, a linear relationship between global mean surface air temperature and sea-ice habitat substantiated the hypothesis that sea-ice thermodynamics can overcome albedo feedbacks proposed to cause sea-ice tipping points. Our outcomes indicate that rapid summer ice losses in models and observations represent increased volatility of a thinning sea- ice cover, rather than tipping-point behaviour. Mitigation-driven Bayesian network outcomes show that previously predicted declines in polar bear distribution and numbers are not unavoidable. Because polar bears are sentinels of the Arctic marine ecosystem and trends in their sea-ice habitats foreshadow future global changes, mitigating greenhouse gas emissions to improve polar bear status would have conservation benefits throughout and beyond the Arctic.

  • Slater, G.J., Figueirido, B., Louis, L., Yang, P., and Van Valkenburgh, B.  Biomechanical consequences of rapid evolution in the polar bear lineage.  PLoS ONE 5(11): art. e13870, 2010.
    Open Access >>  
    Read Abstract >>

    The polar bear is the only living ursid with a fully carnivorous diet. Despite a number of well-documented craniodental adaptations for a diet of seal flesh and blubber, molecular and paleontological data indicate that this morphologically distinct species evolved less than a million years ago from the omnivorous brown bear. To better understand the evolution of this dietary specialization, we used phylogenetic tests to estimate the rate of morphological specialization in polar bears. We then used finite element analysis (FEA) to compare the limits of feeding performance in the polar bear skull to that of the phylogenetically and geographically close brown bear. Results indicate that extremely rapid evolution of semi-aquatic adaptations and dietary specialization in the polar bear lineage produced a cranial morphology that is weaker than that of brown bears and less suited to processing tough omnivorous or herbivorous diets. Our results suggest that continuation of current climate trends could affect polar bears by not only eliminating their primary food source, but also through competition with northward advancing, generalized brown populations for resources that they are ill-equipped to utilize.

  • Sonne, C., Iburg, T., Leifsson, P.S., Born, E.W., Letcher, R.J., and Dietz, R.  Thyroid gland lesions in organohalogen contaminated East Greenland polar bears (Ursus maritimus).  Toxicological and Environmental Chemistry 93(4): 789-805, 2011. 
    Read Abstract >>

    Thyroid gland histology was examined in 20 organohalogen contaminant (OHC)-exposed East Greenland polar bears (Ursus maritimus). OHC concentrations measured in subcutaneous adipose tissue were between 3556 and 28,670 ng g-1 lw for polychlorinated biphenyls (sigma PCB51), 9 and 3403 ng g-1 lw for the sum of organochlorine pesticides (hexachlorocyclo-hexanes, hexachlorobenzene, chlordanes, dichlorodiphenyltrichloroethanes, and dieldrin), and from 21 to 130 ng g-1 lw for polybrominated diphenyl ethers. Histological examinations revealed that 12 of the bears (10 males aged 3-19 years and two females aged 4-7 years) had normal thyroid tissue while eight bears (40%) of varying ages and genders (three males aged 3-9 years and five females aged 4-25 years) showed clear histological lesions including parafollicular C-cell proliferation, nodular hyperplasia, and interstitial fibrosis. No significant differences were found in prevalence of thyroid gland lesions between males and females. Similarly, no marked difference was found in mean age between individuals with and without lesions. There was no significant difference in OHC mean concentrations between males and females or between individuals with and without lesions. Despite no documented relationship to OHC concentrations in adipose tissue, it is worth noting that the lesions were similar to that of OHC exposed lab and wildlife contaminated mammals. Since the lesions were not associated with age or gender, other environmental factors such as energetic stress and autoimmunity/genetic predisposition also need to be considered. It is therefore possible that OHCs, in combination with other environmental and intrinsic factors described in the literature, may interfere with the hypothalamic-pituitary-thyroid axis (HPT axis) resulting in endocrine perturbations in East Greenland polar bears.

  • Durner, G.M., Whiteman, J.P., Harlow, H.J., Amstrup, S.C., Regehr, E.V., and Ben-David, M.  Consequences of long-distance swimming and travel over deep-water pack ice for a female polar bear during a year of extreme sea ice retreat.  Polar Biology 34(7): 975-984, 2011. 
    Read Abstract >>

    Polar bears (Ursus maritimus) prefer to live on Arctic sea ice but may swim between ice floes or between sea ice and land. Although anecdotal observations suggest that polar bears are capable of swimming long distances, no data have been available to describe in detail long distance swimming events or the physiological and reproductive consequences of such behavior. Between an initial capture in late August and a recapture in late October 2008, a radio-collared adult female polar bear in the Beaufort Sea made a continuous swim of 687 km over 9 days and then intermittently swam and walked on the sea ice surface an additional 1,800 km. Measures of movement rate, hourly activity, and subcutaneous and external temperature revealed distinct profiles of swimming and walking. Between captures, this polar bear lost 22% of her body mass and her yearling cub. The extraordinary long distance swimming ability of polar bears, which we confirm here, may help them cope with reduced Arctic sea ice. Our observation, however, indicates that long distance swimming in Arctic waters, and travel over deep water pack ice, may result in high energetic costs and compromise reproductive fitness.

  • Peacock, E., Derocher, A.E., Thiemann, G.W., and Stirling, I.  Conservation and management of Canada's polar bears (Ursus maritimus) in a changing Arctic.  Canadian Journal of Zoology 89(5): 371-385, 2011.
    Open Access >>  
    Read Abstract >>

    Canada has an important responsibility for the research, conservation, and management of polar bears (Ursus maritimus Phipps, 1774) because the majority of polar bears in the world occur within the nation's borders. Two fundamental and recent changes for polar bears and their conservation have arisen: (1) the ongoing and projected further decline of sea-ice habitat as a result of climate change and (2) the implementation of aboriginal land claims and treaties in Canada's North. Science has documented empirical links between productivity of polar bear population and sea-ice change. Predictive modeling based on these data has forecast significant declines in polar bear abundance and distribution of polar bears. With the signing of northern land claims and treaties, polar bear management in Canada has integrated local aboriginal participation, values, and knowledge. The interaction of scientific and local perspectives on polar bears as they relate to harvest, climate change, and declining habitat has recently caused controversy. Some conservation, management, and research decisions have been contentious because of gaps in scientific knowledge and the polarization and politicization of the roles of the various stakeholders. With these ecological and governance transitions, there is a need to re-focus and re-direct polar bear conservation in Canada.

  • McKinney, M.A., Letcher, R.J., Aars, J., Born, E.W., Branigan, M., Dietz, R., Evans, T.J., Gabrielsen, G.W., Peacock, E., and Sonne, C.  Flame retardants and legacy contaminants in polar bears from Alaska, Canada, East Greenland and Svalbard, 2005-2008.  Environment International 37(2): 365-374, 2011. 
    Read Abstract >>

    Flame retardants and legacy contaminants were analyzed in adipose tissue from 11 circumpolar polar bear (Ursus maritimus) subpopulations in 2005-2008 spanning Alaska east to Svalbard. Although 37 polybrominated diphenyl ethers (PBDEs), total-(α)-hexabromocyclodo-decane (HBCD), 2 polybrominated biphenyls (PBBs), pentabromotoluene, pentabromoethyl-benzene, hexabromobenzene, 1,2-bis (2,4,6-tribromophenoxy(ethane) and decabromodiphenyl ethane were screened, only 4 PBDEs, total-(α)-HBCD and BB153 were consistently found. Geometric mean ΣPBDE (4.6 - 78.4 ng/g lipid weight (lw)) and BB153 (2.5 - 81.1 ng/g lw) levels were highest in East Greenland (43.2 and 39.2 ng/g lipid weight (lw), respectively), Svalbard (44.4 and 20.9 ng/g lw) and western (38.6 and 30.1 ng/g lw) and southern Hudson Bay (78.4 and 81.1 ng/g lw). Total-(α)-HBCD levels (<0.3 - 41.1 ng/g lw) were lower than ΣPBDE levels in all subpopulations except in Svalbard, consistent with greater European HBCD use versus North American pentaBDE product use. ΣPCB levels were high relative to flame retardants as well as other legacy contaminants and increased from west to east (1797 - 10,537 ng/g lw). ΣCHL levels were highest among legacy organochlorine pesticides and relatively spatially uniform (765 - 3477 ng/g lw). ΣDDT levels were relatively low and spatially variable (31.5 - 206 ng/g lw). However, elevated proportions of p,p'-DDT to ΣDDT in Alaska and Beaufort Sea relative to other subpopulations suggested fresh inputs from vector control use in Asia and/or Africa. Comparing earlier circumpolar polar bear studies, ΣPBDE, total-(α)-HBCD, p,p'-DDE and ΣCHL levels consistently declined, whereas levels of other legacy contaminants did not. International regulations have clearly been effective in reducing levels of several legacy contaminants in polar bears relative to historical levels. However, slow or stalling declines of certain historic pollutants like PCBs and a complex mixture of "new" chemicals continue to be of concern to polar bear health and that of their arctic marine ecosystems.

  • Molnar, P.K., Derocher, A.E., Klanjscek, T., and Lewis, M.A.  Predicting climate change impacts on polar bear litter size.  Nature Communications 2: art. 186, 2011. 
    Read Abstract >>

    Predicting the ecological impacts of climate warming is critical for species conservation. Incorporating future warming into population models, however, is challenging because reproduction and survival cannot be measured for yet unobserved environmental conditions. In this study, we use mechanistic energy budget models and data obtainable under current conditions to predict polar bear litter size under future conditions. In western Hudson Bay, we predict climate warming-induced litter size declines that jeopardize population viability: ~28% of pregnant females failed to reproduce for energetic reasons during the early 1990s, but 40-73% could fail if spring sea ice break-up occurs 1 month earlier than during the 1990s, and 55-100% if break-up occurs 2 months earlier. Simultaneously, mean litter size would decrease by 22-67% and 44-100%, respectively. The expected timeline for these declines varies with climate-model-specific sea ice predictions. Similar litter size declines may occur in over one-third of the global polar bear population.

  • Edwards, C.J. et al.  Ancient hybridization and an Irish origin for the modern polar bear matriline.  Current Biology 21(15): 1251-1258, 2011. 
    Read Abstract >>

    Background  Polar bears (Ursus maritimus) are among those species most susceptible to the rapidly changing arctic climate, and their survival is of global concern. Despite this, little is known about polar bear species history. Future conservation strategies would significantly benefit from an understanding of basic evolutionary information, such as the timing and conditions of their initial divergence from brown bears (U. arctos) or their response to previous environmental change.  Results  We used a spatially explicit phylogeographic model to estimate the dynamics of 242 brown bear and polar bear matrilines sampled throughout the last 120,000 years and across their present and past geographic ranges. Our results show that the present distribution of these matrilines was shaped by a combination of regional stability and rapid, long-distance dispersal from ice-age refugia. In addition, hybridization between polar bears and brown bears may have occurred multiple times throughout the Late Pleistocene.  Conclusions  The reconstructed matrilineal history of brown and polar bears has two striking features. First, it is punctuated by dramatic and discrete climate-driven dispersal events. Second, opportunistic mating between these two species as their ranges overlapped has left a strong genetic imprint. In particular, a likely genetic exchange with extinct Irish brown bears forms the origin of the modern polar bear matriline. This suggests that interspecific hybridization not only may be more common than previously considered but may be a mechanism by which species deal with marginal habitats during periods of environmental deterioration.

  • Dietz, R., Born, E.W., Riget, F., Aubail, A., Sonne, C., Drimmie, R., and Basu, N.  Temporal trends and future predictions of mercury concentrations in Northwest Greenland polar bear (Ursus maritimus) hair.  Environmental Science and Technology 45(4): 1458-1465, 2011. 
    Read Abstract >>

    Hair samples from 117 Northwest Greenland polar bears (Ursus maritimus) were taken during 1892-2008 and analyzed for total mercury (hereafter Hg). The sample represented 28 independent years and the aim of the study was to analyze for temporal Hg trends. Mercury concentrations showed yearly significant increases of 1.6-1.7% (p < 0.0001) from 1892 to 2008 and the two most recent median concentrations from 2006 and 2008 were 23- to 27-fold higher respectively than baseline level from 1300 A.D. In the same region (Nuullit). This indicates that the present (2006-2008) Northwest Greenland polar bear Hg exposure is 95.6-96.2% anthropogenic in its origin. Assuming a continued anthropogenic increase, this model estimated concentrations in 2050 and 2100 will be 40- and 92-fold the baseline concentration, respectively, which is equivalent to a 97.5 and 98.9% man-made contribution. None of the 2001-2008 concentrations of Hg in Northwest Greenland polar bear hair exceeded the general guideline values of 20-30 µg/g dry weight for terrestrial wildlife, whereas the neurochemical effect level of 5.4 µg Hg/g dry weight proposed for East Greenland polar bears was exceeded in 93.5% of the cases. These results call for detailed effect studies in main target organs such as brain, liver, kidney, and sexual organs in the Northwest Greenland polar bears.

  • St. Louis, V.L., Derocher, A.E., Stirling, I., Graydon, J.A., Lee, C., Jocksch, E., Richardson, E., Ghorpade, S., Kwan, A.K., Kirk, J.L., Lehnherr, I., and Swanson, H.K.  Differences in mercury bioaccumulation between polar bears (Ursus maritimus) from the Canadian high- and sub-Arctic.  Environmental Science and Technology 45(14): 5922-5928, 2011. 
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    Polar bears (Ursus maritimus) are being impacted by climate change and increased exposure to pollutants throughout their northern circumpolar range. In this study, we quantified concentrations of total mercury (THg) in the hair of polar bears from Canadian high- (southern Beaufort Sea, SBS) and sub- (western Hudson Bay, WHB) Arctic populations. Concentrations of THg in polar bears from the SBS population (14.8 ± 6.6 μg g–1) were significantly higher than in polar bears from WHB (4.1 ± 1.0 μg g–1). On the basis of δ15N signatures in hair, in conjunction with published δ15N signatures in particulate organic matter and sediments, we estimated that the pelagic and benthic food webs in the SBS are ~4.7 and ~4.0 trophic levels long, whereas in WHB they are only 3.6 and 3.3 trophic levels long. Furthermore, the more depleted δ13C ratios in hair from SBS polar bears relative to those from WHB suggests that SBS polar bears feed on food webs that are relatively more pelagic (and longer), whereas polar bears from WHB feed on those that are relatively more benthic (and shorter). Food web length and structure accounted for 67% of the variation we found in THg concentrations among all polar bears across both populations. The regional difference in polar bear hair THg concentrations was also likely due to regional differences in water-column concentrations of methyl Hg (the toxic form of Hg that biomagnifies through food webs) available for bioaccumulation at the base of the food webs. For example, concentrations of methylated Hg at mid-depths in the marine water column of the northern Canadian Arctic Archipelago were 79.8 ± 37.3 pg L–1, whereas, in HB, they averaged only 38.3 ± 16.6 pg L–1. We conclude that a longer food web and higher pelagic concentrations of methylated Hg available to initiate bioaccumulation in the BS resulted in higher concentrations of THg in polar bears from the SBS region compared to those inhabiting the western coast of HB.

  • Routti, H., Letcher, R.J., Born, E.W., Branigan, M., Dietz, R., Evans, T.J., Fisk, A.T., Peacock, E., and Sonne, C.  Spatial and temporal trends of selected trace elements in liver tissue from polar bears (Ursus maritimus) from Alaska, Canada and Greenland.  Journal of Environmental Monitoring 13(8): 2260-2267, 2011. 
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    Spatial trends and comparative changes in time of selected trace elements were studied in liver tissue from polar bears from ten different subpopulation locations in Alaska, Canadian Arctic and East Greenland. For nine of the trace elements (As, Cd, Cu, Hg, Mn, Pb, Rb, Se and Zn) spatial trends were investigated in 136 specimens sampled during 2005-2008 from bears from these ten subpopulations. Concentrations of Hg, Se and As were highest in the (northern and southern) Beaufort Sea area and lowest in (western and southern) Hudson Bay area and Chukchi/Bering Sea. In contrast, concentrations of Cd showed an increasing trend from east to west. Minor or no spatial trends were observed for Cu, Mn, Rb and Zn. Spatial trends were in agreement with previous studies, possibly explained by natural phenomena. To assess temporal changes of Cd, Hg, Se and Zn concentrations during the last decades, we compared our results to previously published data. These time comparisons suggested recent Hg increase in East Greenland polar bears. This may be related to Hg emissions and/or climate-induced changes in Hg cycles or changes in the polar bear food web related to global warming. Also, Hg:Se molar ratio has increased in East Greenland polar bears, which suggests there may be an increased risk for Hg2+-mediated toxicity. Since the underlying reasons for spatial trends or changes in time of trace elements in the Arctic are still largely unknown, future studies should focus on the role of changing climate and trace metal emissions on geographical and temporal trends of trace elements.

Pinnipeds

  • Ray, G.C., Overland, J.E., and Hufford, G.L.  Seascape as an organizing principle for evaluating walrus and seal sea-ice habitat in Beringia.  Geophysical Research Letters 37(20): art. L20504, 2010. 
    Read Abstract >>

    The term "seascape", as used here, relates the natural history of ice-dependent pinnipeds to their sea-ice environments at different spatial scales, following concepts of landscape ecology. Habitats are characterized by heterogeneous but repeatable structures of sea ice. As an example, multiple mesoscale (3-50 km) seascapes present conditions for different ecological preferences of five Beringian ice-dependent pinnipeds, as observed during 2006-2009 winter-spring icebreaker cruises. Seascape partitioning concepts are important for understanding and projecting species' responses to change under climate-change scenarios.

  • Vanden Berghe, M., Mat, A., Arriola, A., Polain, S., Stekke, V., Thome, J.P., Gaspart, F., Pomeroy, P., Larondelle, Y., and Debier, C.  Relationships between vitamin A and PCBs in grey seal mothers and pups during lactation.  Environmental Pollution 158(5): 1570-1575, 2010. 
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    A previous study has shown a simultaneous increase of vitamin A and PCBs in grey seal (Halichoerus grypus) milk at late lactation (Debier et al., 2004). Here we sought to understand this unexpected relationship by comparing the dynamics of vitamin A and PCBs in the different tissue compartments of transfer. Lactating grey seals and their pups were sampled longitudinally in Scotland during the 2006 breeding season. As blubber reserves decreased, concentrations of vitamin A and PCBs increased during lactation in the inner layer of maternal blubber. A concomitant rise was observed in milk and consequently in the serum of suckling pups. The similar dynamics of vitamin A and PCBs in milk and inner blubber suggest a common mechanism of mobilisation from maternal body stores and transfer into the milk. A panel data analysis highlighted a negative impact of PCBs in milk and pup serum on vitamin A status in pup serum.

  • Wang, J., Hülck, K., Hong, S.-M., Atkinson, S., and Li, Q.X.  Accumulation and maternal transfer of polychlorinated biphenyls in Steller sea lions (Eumetopias jubatus) from Prince William Sound and the Bering Sea, Alaska.  Environmental Pollution 159(1): 71-77, 2011. 
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    The western stock of the Steller sea lion (Eumetopias jubatus) in the northern Pacific Ocean has declined by approximately 80% over the past 30 years. This led to the listing of this sea lion population as an endangered species in 1997. Chemical pollution is a one of several contributing causes. In the present study, 145 individual PCBs were determined in tissues of male sea lions from Tatitlek (Prince William Sound) and St. Paul Island (Bering Sea), and placentae from the Aleutian Islands. PCBs 90/101, 118, and 153 were abundant in all the samples. The mean toxic equivalents (TEQ) were 2.6, 4.7 and 7.4 pg/g lw in the kidney, liver, and blubber samples, respectively. The mean TEQ in placentae was 8 pg/g lw. Total PCBs concentrations (2.6-7.9 mg/g lw) in livers of some males were within a range known to cause physiological effects, further suggesting the possibility of adverse effects on this stock.

  • Mathews, E.A. and Adkison, M.D.  The role of Steller sea lions in a large population decline of harbor seals.  Marine Mammal Science 26(4): 803-836, 2010. 
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    We provide the first direct evidence that Steller sea lions will prey on harbor seals. Direct observations of predation on marine mammals at sea are rare, but when observed rates of predation are extrapolated, predation mortality may be found to be significant. From 1992 to 2002, harbor seals in Glacier Bay declined steeply, from 6,200 to 2,500 (~65%). After documenting that Steller sea lions were preying on seals in Glacier Bay, we investigated increased predation by sea lions as a potential explanation for the large decline. In five independent data sets spanning 21-25 yr and including 14,308 d of observations, 13 predation events were recorded. We conducted a fine-scale analysis for an intensively studied haul-out (Spider Island) and a broader analysis of all of Glacier Bay. At Spider Island, estimated predation by sea lions increased and could account for the entirety of annual pup production in 5 of 8 yr since 1995. The predation rate, however, was not proportional to the number of predators. Predation by Steller sea lions is a new source of mortality that contributed to the seal declines; however, life history modeling indicates that it is unlikely that sea lion predation is the sole factor responsible for the large declines.

  • Speckman, S.G., Chernook, V.I., Burn, D.M., Udevitz, M.S., Kochnev, A.A., Vasilev, A., Jay, C.V., Lisovsky, A., Fischbach, A.S., and Benter, R.B.  Results and evaluation of a survey to estimate Pacific walrus population size, 2006.  Marine Mammal Science 27(3): 514-553, 2011. 
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    In spring 2006, we conducted a collaborative U.S.-Russia survey to estimate abundance of the Pacific walrus (Odobenus rosmarus divergens). The Bering Sea was partitioned into survey blocks, and a systematic random sample of transects within a subset of the blocks was surveyed with airborne thermal scanners using standard strip-transect methodology. Counts of walruses in photographed groups were used to model the relation between thermal signatures and the number of walruses in groups, which was used to estimate the number of walruses in groups that were detected by the scanner but not photographed. We also modeled the probability of thermally detecting various-sized walrus groups to estimate the number of walruses in groups undetected by the scanner. We used data from radio-tagged walruses to adjust on-ice estimates to account for walruses in the water during the survey. The estimated area of available habitat averaged 668,000 km² and the area of surveyed blocks was 318,204 km². The number of Pacific walruses within the surveyed area was estimated at 129,000 with 95% confidence limits of 55,000 - 507,000 individuals. Poor weather conditions precluded surveying in other areas; therefore, this value represents the number of Pacific walruses within about half of potential walrus habitat.

  • Boyd, I.L.  Assessing the effectiveness of conservation measures: Resolving the ''wicked'' problem of the Steller sea lion.  Biological Conservation 143(7): 1664-1674, 2010. 
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    ''Wicked'' problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.

  • French, S.S., González-Suárez, M., Young, J.K., Durham, S., and Gerber, L.R.  Human disturbance influences reproductive success and growth rate in California sea lions (Zalophus californianus).  PLoS ONE 6(3): art. e17686, 2011.
    Open Access >>  
    Read Abstract >>

    The environment is currently undergoing changes at both global (e.g., climate change) and local (e.g., tourism, pollution, habitat modification) scales that have the capacity to affect the viability of animal and plant populations. Many of these changes, such as human disturbance, have an anthropogenic origin and therefore may be mitigated by management action. To do so requires an understanding of the impact of human activities and changing environmental conditions on population dynamics. We investigated the influence of human activity on important life history parameters (reproductive rate, and body condition, and growth rate of neonate pups) for California sea lions (Zalophus californianus) in the Gulf of California, Mexico. Increased human presence was associated with lower reproductive rates, which translated into reduced long-term population growth rates and suggested that human activities are a disturbance that could lead to population declines. We also observed higher body growth rates in pups with increased exposure to humans. Increased growth rates in pups may reflect a density dependent response to declining reproductive rates (e.g., decreased competition for resources). Our results highlight the potentially complex changes in life history parameters that may result from human disturbance, and their implication for population dynamics. We recommend careful monitoring of human activities in the Gulf of California and emphasize the importance of management strategies that explicitly consider the potential impact of human activities such as ecotourism on vertebrate populations.

  • Mos, L., Cameron, M., Jeffries, S.J., Koop, B.F., and Ross, P.S.  Risk-based analysis of polychlorinated biphenyl toxicity in harbor seals.  Integrated Environmental Assessment and Management 6(4): 631-640, 2010. 
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    Persistent organic pollutants (POPs) have been associated with adverse health effects in marine mammals. However, the complex mixtures to which free-ranging populations are exposed constrain the elucidation of cause-and-effect relationships between specific POPs and the observed health risks. In this study, we 1) assembled data from studies showing polychlorinated biphenyl (PCB)-associated effects on the health of free-ranging harbor seals in the northeastern Pacific Ocean, 2) carried out additional POP analyses on seal samples to broaden the available data on contaminant residues, and 3) derived estimates of individual POPs and their toxic risks. Taken together, these components were used to generate a new toxicity reference value (TRV) for the protection of marine mammal health. In this case study of seals in British Columbia, Canada, and Washington State, USA, PCBs were the single most abundant POP and were correlated with several adverse health effects. PCB exposures consistently exceeded regulatory toxicity thresholds for fish-eating wildlife. Nursing seal pups were at particular risk, reflecting their greatly increased dietary intake of PCBs and their sensitivity to developmental toxicity. Based on the collective evidence obtained, we propose TRVs (consisting of 5% tissue residue concentration and dose) of 1.3 mg/kg lipid weight tissue residue in blubber and 0.05 mg/kg lipid weight tolerable daily intake in prey. Insofar as the TRVs are lower than previously established TRVs and regulatory guidelines, our study highlights the current underestimation of risks associated with PCBs in high-trophic-level wildlife.

  • Lynch, M., Duignan, P.J., Taylor, T., Nielsen, O., Kirkwood, R., Gibbens, J., and Arnould, J.P.Y.  Epizootology of Brucella infection in Australian fur seals.  Journal of Wildlife Diseases 47(2): 352-363, 2011. 
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    Novel members of the bacterial genus Brucella have recently emerged as pathogens of various marine mammal species and as potential zoonotic agents. We investigated the epizootiology of Brucella infection in Australian fur seals (Arctocephalus pusillus doriferus) by establishing demographic and temporal variations in antibody prevalence, attempting isolation of the causative agent, and determining whether this potential pathogen is involved in frequent abortions observed in this pinniped species. Two competitive enzyme-linked immunosorbent assays (cELISAs), an indirect ELISA, and a fluorescence polarization assay (FPA) were used to test sera for Brucella antibodies. The FPA and cELISA proved suitable for use in this species. Significant differences in antibody prevalence were found between age classes of seals sampled between 2007 and 2009 at one colony. Pups sampled at this site (n = 134) were negative for Brucella antibodies by all serologic tests but 17 of 45 (38%) of juveniles were antibody-positive. Antibody prevalence in adult females was significantly higher than in juveniles (P = 0.044). Antibody prevalence for adult females between 2003 and 2009 varied significantly over time (P = 0.011), and for individuals sampled between 2003 and 2005, the likelihood of pregnancy was greater in individuals positive for Brucella antibodies (P = 0.034). Inflammatory lesions suggestive of infectious agents were found in 14 of 39 aborted Australian fur seal pups, but pathologic changes were not uniformly consistent for Brucella  infection. Culture and PCR investigations on fetal tissues were negative for Brucella. Culture and PCR on selected fresh or frozen tissues from 36 juvenile and adult animals were also negative. We suspect that the prevalence of active infection with Brucella in Australian fur seals is low relative to antibody prevalence.

  • Ayling, R.A., Bashiruddin, S., Davison, N.J., Foster, G., Dagleish, M.P., and Nicholas, R.A.J.  The occurrence of Mycoplasma phocicerebrale, Mycoplasma phocidae, and Mycoplasma phocirhinis in Grey and Common Seals (Halichoerus grypus and Phoca vitulina) in the United Kingdom.  Journal of Wildlife Diseases 47(2): 471-475, 2011. 
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    Following the isolation of Mycoplasma phocicerebrale from the flipper wound of a grey seal (Halichoerus grypus) in Cornwall, UK, surveillance for Mycoplasma species was extended to include other seals rescued or found dead around the UK. Mycoplasma phocicerebrale was frequently detected from the teeth of seals and from infected wounds and respiratory tracts. Mycoplasma phocirhinis, Mycoplasma phocidae, and some unidentified Mycoplasma species were also detected. Mycoplasma phocicerebrale and M. phocidae were the only bacteria consistently identified from the wound infections, but their role in respiratory and other diseases remains unknown, as other bacteria were also isolated from respiratory sites.

  • Vorkamp, K., Riget, F.F., Bossi, R., and Dietz, R.  Temporal trends of hexabromocyclododecane, polybrominated diphenyl ethers and polychlorinated biphenyls in ringed seals from East Greenland.  Environmental Science and Technology 45(4): 1243-1249, 2011. 
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    Concentrations of hexabromocyclododecane (HBCD) were determined in a combination of archived and fresh blubber samples of juvenile ringed seals from East Greenland collected between 1986 and 2008. α-HBCD was the only diastereoisomer consistently above levels of quantification and showed a significant log-linear (exponential) increase from 2.0 to 8.7 ng/g lipid weight (median concentrations) with an annual rate of +6.1%. The concentrations were up to several orders of magnitude lower than those reported for marine mammals from industrialized areas. Previously presented time trends on polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) have been extended with new data for 2006 and 2008. ΣPBDE in juvenile seals was the only parameter with a slight upward trend, however, dependent on the low 1986 concentration. Removing this data point resulted in a downward trend, which also was found for adult seals with a time trend starting in 1994. ΣPCB decreased significantly in juvenile seals, again due to the 1986 value, while no trend was found for the adult animals. This indicates stagnating PCB concentrations at a relatively high level, in some cases possibly exceeding tolerable daily intake rates for seal blubber as traditional Arctic food items.

  • Bottein, M.-Y.D., Kashinsky, L., Wang, Z., Littnan, C., and Ramsdell, J.S.  Identification of ciguatoxins in Hawaiian monk seals Monachus schauinslandi from the Northwestern and Main Hawaiian Islands.  Environmental Science and Technology 45(12): 5403-5409, 2011. 
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    Ciguatoxins are potent algal neurotoxins that concentrate in fish preyed upon by the critically endangered Hawaiian monk seal (Monachus schauinslandi). The only report for Hawaiian monk seal exposure to ciguatoxins occurred during a 1978 mortality event when two seal liver extracts tested positive by mouse bioassay. Ciguatoxins were thus proposed as a potential threat to the Hawaiian monk seal population. To reinvestigate monk seal exposure to ciguatoxins we utilized more selective detection methods, the Neuro-2A cytotoxicity assay, to quantify ciguatoxin activity and an analytical method LC-MS/MS to confirm the molecular structure. Tissue analysis from dead stranded animals revealed ciguatoxin activity in brain, liver, and muscle, whereas analysis of blood samples from 55 free-ranging animals revealed detectable levels of ciguatoxin activity (0.43 to 5.49 pg/mL P-CTX-1 equiv) in 19% of the animals. Bioassay-guided LC fractionation of two monk seal liver extracts identified several ciguatoxin-like peaks of activity including a peak corresponding to the P-CTX-3C which was confirmed present by LC-MS/MS. In conclusion, this work provides first confirmation that Hawaiian monk seals are exposed to significant levels of ciguatoxins and first evidence of transfer of ciguatoxin to marine mammals. This threat could pose management challenges for this endangered marine mammal  species.

  • Authier, M., Delord, K., and Guinet, C.  Population trends of female Elephant Seals breeding on the Courbet Peninsula, Iles Kerguelen.  Polar Biology 34(3): 319-328, 2011. 
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    Southern Elephant Seals are upper marine predators of the Southern Ocean. As such, their population dynamics and fluctuations reflect environment conditions. Their worldwide populations crashed during the second half of the twentieth century for reasons not yet completely elucidated. Here, we studied the largest population of Southern Elephant Seals within the South Indian Ocean that are breeding on Iles Kerguelen. In a previous analysis, Guinet et al. in Antarct Sci 11:193-197, 1999) suggested that the decline on lles Kerguelen might be over, as observed elsewhere. Using 10 years of additional data, we updated this analysis using state-of-the-art statistical methods to account for most uncertainties associated with count data. We showed that the population of female Southern Elephant Seals breeding on lies Kerguelen has been stable over the past 20 years. Despite concomitant global changes within the Southern Ocean, we did not find any evidence of a phenological shift in peak haul-out date of breeding females between the 1970s and the 2000s.

  • Jay, C.V., Marcot, B.G., and Douglas, D.C.  Projected status of the Pacific walrus (Odobenus rosmarus divergens) in the twenty-first century.  Polar Biology 34(7): 1065-1084, 2011. 
    Read Abstract >>

    Extensive and rapid losses of sea ice in the Arctic have raised conservation concerns for the Pacific walrus (Odobenus rosmarus divergens), a large pinniped inhabiting arctic and subarctic continental shelf waters of the Chukchi and Bering seas. We developed a Bayesian network model to integrate potential effects of changing environmental conditions and anthropogenic stressors on the future status of the Pacific walrus population at four periods through the twenty-first century. The model framework allowed for inclusion of various sources and levels of knowledge, and representation of structural and parameter uncertainties. Walrus outcome probabilities through the century reflected a clear trend of worsening conditions for the subspecies. From the current observation period to the end of century, the greatest change in walrus outcome probabilities was a progressive decrease in the outcome state of robust and a concomitant increase in the outcome state of vulnerable. The probabilities of rare and extirpated states each progressively increased but remained <10% through the end of the century. The summed probabilities of vulnerable, rare, and extirpated (P(v,r,e)) increased from a current level of 10% in 2004 to 22% by 2050 and 40% by 2095. The degree of uncertainty in walrus outcomes increased monotonically over future periods. In the model, sea ice habitat (particularly for summer/fall) and harvest levels had the greatest influence on future population outcomes. Other potential stressors had much smaller influences on walrus outcomes, mostly because of uncertainty in their future states and our current poor understanding of their mechanistic influence on walrus abundance.

  • Robertson, B.C. and Chilvers, B.L.  The population decline of the New Zealand sea lion Phocarctos hookeri: a review of possible causes.  Mammal Review 41(4): 253-275, 2011.
    Open Access >>  
    Read Abstract >>

    1.  The New Zealand (NZ) sea lion Phocarctos hookeri is NZ's only endemic pinniped and is listed as 'nationally critical'. The species breeds in the NZ sub-Antarctic: 71% of the population at the Auckland Islands (2010 pup production: 1814 ± 39) and the remaining 29% on Campbell Island (726 pups in 2010).  2.  Pup production at the Auckland Islands has declined by 40% since 1998 (1998: 3021 pups produced): only 1501 pups were born in 2009. This decline is directly linked to philopatric females not returning to breeding areas. While the Auckland Island population has declined, the Campbell Island population appears to be increasing slowly.  3.  Potential reasons for the decline in the Auckland Island population, but not in the Campbell Island population, include non-anthropogenic factors: (i) disease epizootics, (ii) predation, (iii) permanent dispersal or migration, (iv) environmental change; and anthropogenic impacts: (v) population 'overshoot', (vi) genetic effects, (vii) effects of contaminants, (viii) indirect effects of fisheries (i.e. resource competition) and (ix) direct effects of fisheries (i.e. by-catch deaths). Of the nine potential reasons examined here, six can be discounted (ii–vii). Bacterial epizootics (i) occur in the NZ sea lion population, but their impact has predominantly increased pup mortality, which is unlikely to cause the severe decline observed, as pup mortality throughout the species is naturally high and variable.  4.  The most plausible hypotheses, based on available evidence, are that the observed decline, in particular, the decreasing number of breeding females in the Auckland Island population, is caused by (viii) fisheries-induced resource competition and (ix) fisheries-related by-catch. By-catch is the main known anthropogenic cause of mortality in the species. Competition with fisheries resulting in resource competition, nutrient stress and decreased reproductive ability in NZ sea lions should be a priority area for future research.

  • Kakuschke, A., Valentine-Thon, E., Griesel, S., Fonfara, S., Siebert, U., and Prange, A.  Are metal-induced hypersensitivities in harbor seals associated with liver function?  Marine Pollution Bulletin 62(8): 1891-1894, 2011. 
    Read Abstract >>

    Environmental exposure to metals is believed to affect marine mammal health adversely including immunosuppression or acute as well as chronic inflammatory processes leading to hypersensitivities or autoimmune diseases. Metal-specific hypersensitivities were found in several pinnipeds of the North Sea. However, hypersensitivity is a complex phenomenon whose characteristics are still not completely understood; in particular, effects on health are not well established. In the present study, we compared basic hematological and biochemical parameters of seals with and without metal-specific hypersensitivities. We found altered hematological parameters and liver enzyme patterns in seals with a metal-induced hypersensitivity, including a reduction in macrophages, an increase in lymphocytes, and elevated levels of lactate dehydrogenase. These findings support the suggestion of a chronic influence of metal pollutants on the health of marine mammals of the North Sea.

  • Frouin, H., Lebeuf, M., Hammill, M., Sjare, B., and Fournier, M.  PBDEs in serum and blubber of harbor, grey and harp seal pups from Eastern Canada.  Chemosphere 82(5): 663-669, 2011. 
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    Serum and blubber of pup harbor (Phoca vitulina), grey (Halichoerus grypus) and harp (Phoca groenlandica) seals from the Estuary and the Gulf of St. Lawrence were analyzed for polybrominated diphenyl ethers (PBDEs). Concentrations of SPBDEs (on lipid weight basis) in tissues of harbor seal pups inhabiting the St. Lawrence Estuary were about five times higher than in those from a colony located in the northern Gulf. Harp seal pups have the lowest levels of SPBDEs among the seal species born in the Gulf of St. Lawrence. Lipid normalized concentrations of SPBDEs in serum and blubber were strongly correlated, suggesting that the blood collection as a less invasive method could be used to monitor SPBDEs in pups. This study shows that fluvial inputs of PBDEs are important to the St. Lawrence marine ecosystem and that inhabiting harbor seal pups have a substantial exposure to PBDEs at a critical developmental stage. In addition, the observed difference in PBDE levels between harp and grey or harbor seal pups from the Gulf of St. Lawrence is explained by the difference in diets of their mothers which is linked with their residency time in the Gulf and their seasonal migration pattern.

  • Hoover-Miller, A., Atkinson, S., Conlon, S., Prewitt, J., and Armato, P.  Persistent decline in abundance of harbor seals Phoca vitulina richardsi over three decades in Aialik Bay, an Alaskan tidewater glacial fjord.  Marine Ecology Progress Series 424: 259-271, 2011. 
    Read Abstract >>

    Glacial ice calved from tidewater glaciers in Alaska provides an important haulout habitat for harbor seals Phoca vitulina richardsi, and its extent and ecological influence is being reduced by climate change. The number of harbor seals using glacial ice adjacent to Aialik Glacier, central Gulf of Alaska, declined by 93% from 1979 to 2009. During this time, seals demonstrated variability in their selection of haulout locations, particularly during the molt. Near Pedersen Glacier, 6 km south of Aialik Glacier, the number of seals doubled from 2005 to 2007; this was followed by an equivalent loss from 2007 to 2009. This influx, which occurred during a period of cold marine conditions, was associated with the arrival of seals from locations outside Aialik Bay, rather than from movements of seals from Aialik Glacier. Nearly all pups were born near Aialik Glacier. Pup production, which was stable from 1979 to 1983, subsequently declined by 12.4% yr-1 through 1994. Although the rate of decline abated, the numbers of pups continued to decline by 4.6% annually from 1994 to 2009. The persistent decline of harbor seals in Aialik Bay is similar to that observed in Glacier Bay, southeast Alaska, but contrasts with trends at nonglacial sites in the Gulf of Alaska and southeast Alaska where populations have been increasing since the mid-1990s. Results indicate flexibility in selection of haulout location and potentially the proportion of time seals are present on the ice. The persistent decline in pup production, however, raises concern over the future of harbor seals in previously important glacial pupping habitats and the integrity of unique glacial fjord ecosystems.

Cetaceans

  • Gende, S.M., Hendrix, A.N., Harris, K.R., Eichenlaub, B., Nielsen, J., and Pyare, S.  A Bayesian approach for understanding the role of ship speed in whale–ship encounters.  Ecological Applications 21(6): 2232-2240, 2011. 
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    Mandatory or voluntary reductions in ship speed are a common management strategy for reducing deleterious encounters between large ships and large whales. This has produced strong resistance from shipping and marine transportation entities, in part because very few studies have empirically demonstrated whether or to what degree ship speed influences ship-whale encounters. Here we present the results of four years of humpback whale sightings made by observers aboard cruise ships in Alaska, representing 380 cruises and 891 ship-whale encounters. Encounters occurred at distances from 21 m to 1000 m ( = 567 m) with 61 encounters (7%) occurring between 200 m and 100 m, and 19 encounters (2%) within 100 m. Encounters were spatially aggregated and highly variable across all ship speeds. Nevertheless a Bayesian change-point model found that the relationship between whale distance and ship speed changed at 11.8 knots (6.1 m/s) with whales encountering ships, on average, 114 m closer when ship speeds were above 11.8 knots. Binning encounter distances by 1-knot speed increments revealed a clear decrease in encounter distance with increasing ship speed over the range of 7 - 17 knots (3.6 - 8.7 m/s). Our results are the first to demonstrate that speed influences the encounter distance between large ships and large whales. Assuming that the closer ships come to whales the more likely they are to be struck, our results suggest that reduced ship speed may be an effective management action in reducing the probability of a collision.

  • Schwacke, L.H., Twiner, M.J., DeGuise, S., Balmer, B.C., Wells, R.S., Townsend, F.I., Rotstein, D.C., Varela, R.A., Hansen, L.J., Zolman, E.S., Spradlin, T.R., Levin, M., Leibrecht, H., Wang, Z. H., and Rowles, T.K.  Eosinophilia and biotoxin exposure in bottlenose dolphins (Tursiops truncatus) from a coastal area impacted by repeated mortality events.  Environmental Research 110(6): 548-555, 2010. 
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    Bottlenose dolphins (Tursiops truncatus) inhabiting coastal waters in the northern Gulf of Mexico have been impacted by recurrent unusual mortality events over the past few decades. Several of these mortality events along the Florida panhandle have been tentatively attributed to poisoning from brevetoxin produced by the dinoflagellate Karenia brevis. While dolphins in other regions of the Florida coast are often exposed to K. brevis blooms, large-scale dolphin mortality events are relatively rare and the frequency and magnitude of die-offs along the Panhandle raise concern for the apparent vulnerability of dolphins in this region. We report results from dolphin health assessments conducted near St. Joseph Bay, Florida, an area impacted by 3 unusual die-offs within a 7-year time span. An eosinophilia syndrome, manifested as an elevated blood eosinophil count without obvious cause, was observed in 23% of sampled dolphins. Elevated eosinophil counts were associated with decreased T-lymphocyte proliferation and increased neutrophil phagocytosis. In addition, indication of chronic low-level exposure to another algal toxin, domoic acid produced by the diatom Pseudo-nitzschia spp., was determined. Previous studies of other marine mammal populations exposed recurrently to Pseudo-nitzschia blooms have suggested a possible link between the eosinophilia and domoic acid exposure. While the chronic eosinophilia syndrome could over the long-term produce organ damage and alter immunological status and thereby increase vulnerability to other challenges, the significance of the high prevalence of the syndrome to the observed mortality events in the St. Joseph Bay area is unclear. Nonetheless, the unusual immunological findings and concurrent evidence of domoic acid exposure in this sentinel marine species suggest a need for further investigation to elucidate potential links between chronic, low-level exposure to algal toxins and immune health.

  • Slooten, E. and Dawson, S.M.  Assessing the effectiveness of conservation management decisions: likely effects of new protection measures for Hector's dolphin (Cephalorhynchus hectori).  Aquatic Conservation: Marine and Freshwater Ecosystems 20(3): 334-347, 2010. 
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    1. Fisheries bycatch affects many species of marine mammals, seabirds, turtles and other marine animals. 2. New Zealand's endemic Hector's dolphins overlap with gillnet and trawl fisheries throughout their geographic range. The species is listed as Endangered by the IUCN. In addition, the North Island subspecies has been listed as Critically Endangered. 3. Estimates of catch rates in commercial gillnets from an observer programme (there are no quantitative estimates of bycatch by amateur gillnetters or in trawl fisheries) were used in a simple population viability analysis to predict the impact of this fishery under three scenarios: Option (A) status-quo management, (B) new regulations announced by the Minister of Fisheries in 2008 and (C) total protection. 4. Uncertainty in estimates of population size and growth rate, number of dolphins caught and other model inputs are explicitly included in the analysis. Sensitivity analyses are carried out to examine the effect of variation in catch rate and the extent to which fishing effort is removed from protected areas but displaced to unprotected areas. 5. These methods are applicable to many other situations in which animals are removed from populations, whether deliberately (e.g. fishing) or not (e.g. bycatch). 6. The current Hector's dolphin population is clearly depleted, at an estimated 27% of the 1970 population. Population projections to 2050 under Options A and B predict that the total population is likely to continue declining. In the case of Option B this is driven mainly by continuing bycatch due to the much weaker protection measures on the South Island west coast. 7. Without fishing mortality (Option C) all populations are projected to increase, with the total population approximately doubling by 2050 and reaching half of its 1970 population size in just under 40 years.

  • Bearzi, G., Agazzi, S., Gonzalvo, J., Bonizzoni, S., Costa, M., and Petroselli, A.  Biomass removal by dolphins and fisheries in a Mediterranean Sea coastal area: do dolphins have an ecological impact on fisheries?  Aquatic Conservation: Marine and Freshwater Ecosystems 20(5): 549-559, 2010. 
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    1. Dolphins are often claimed to compete with fisheries, including through removal of substantial biomass. To calculate the biomass removed by fisheries and the degree of resource overlap with dolphins in a coastal area of Greece, estimates of dolphin abundance based on photographic capture-recapture were combined with an assessment of fishing effort and catch. 2. The estimated total biomass consumed annually by local dolphin populations – 15 short-beaked common dolphins and 42 common bottlenose dolphins – was 15.5 and 89.8 tonnes, respectively. The total biomass removed by the local fishing fleet (307 fishing boats) was 3469.2 tonnes, i.e. about 33 times greater than that removed by dolphins. 3. Dolphins removed 2.9% of the total biomass, fisheries 97.1%. Nine purse seiners (representing only 3% of the active fishing fleet) were responsible for 31.9% of biomass removal. Similarity of biomass composition between dolphins and fisheries was expressed by a Pianka index of 0.46 for common dolphins and 0.66 for bottlenose dolphins. 4. Overlap differed according to fishing gear. Common dolphin overlap was higher with purse seiners (0.82), and lower with beach seiners (0.31), bottom trawlers (0.11) and trammel boats (0.06). There was virtually no overlap with longliners (0.02). Bottlenose dolphin overlap was higher with trammel boats (0.89) and bottom trawlers (0.75), and lower with longliners (0.38), purse seiners (0.24) and beach seiners (0.18). There was minimal overlap (0.12) between the two dolphin species. 5. This study suggests that ecological interactions between dolphins and fisheries in this coastal area have minor effects on fisheries. Conversely, prey depletion resulting from overfishing can negatively affect dolphins. Fisheries management measures consistent with national and EU legislation are proposed to ensure sustainability and to protect marine biodiversity.

  • Ross, P.S., Dungan, S.Z., Hung, S.K., Jefferson, T.A., MacFarquhar, C., Perrin, W.F., Riehl, K.N., Slooten, E., Tsai, J., Wang, J.Y., White, B.N., Wursig, B., Yang, S.C., and Reeves, R.R.  Averting the baiji syndrome: conserving habitat for critically endangered dolphins in Eastern Taiwan Strait.  Aquatic Conservation: Marine and Freshwater Ecosystems 20(6): 685-694, 2010. 
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    1. Numbering no more than 100 individuals and facing many threats, the geographically isolated Eastern Taiwan Strait population of Indo-Pacific humpback dolphins (Sousa chinensis) is in peril. The estuarine and coastal waters of central-western Taiwan have historically provided prime habitat for these dolphins, but environmental conditions today bear little resemblance to what they were in the past. 2. The humpback dolphins must share their habitat with thousands of fishing vessels and numerous factories built upon thousands of hectares of reclaimed land. 3. They are exposed to chemicals and sewage released from adjacent terrestrial activities. Noise and disturbance associated with construction, vessel traffic and military activities are features of everyday life for these animals. 4. Measures to slow the pace of habitat deterioration and reduce the many risks to the dolphins are urgently needed. As one practical step in this direction, this paper describes the habitat needs of these small cetaceans so that decision makers will be better equipped to define 'priority habitat' and implement much needed protection measures under the terms of local legislation. 5. The preferred habitat of these dolphins in Taiwan consists of shallow (<30 m), near-shore marine waters with regular freshwater inputs. 6. For such a small, isolated and threatened population, 'priority habitat' should not be limited to areas of particularly intensive dolphin use or high dolphin density, but rather it should encompass the entire area where the animals have been observed (their current 'habitat'), as well as additional coastal areas with similar biophysical features ('suitable habitat'). Such a precautionary approach is warranted because the loss of only a few individuals could have serious population-level consequences. 7. While conventional socio-economic analysis might suggest that implementing protection measures over an area stretching ~350 km north-south along Taiwan's west coast and ~3 km out to sea would be too 'costly', the loss of this charismatic species from Taiwan's waters would send a troubling message regarding our collective ability to reconcile human activities with environmental sustainability.

  • Richard, P.R., Laake, J.L., Hobbs, R.C., Heide-Jorgensen, M.P., Asselin, N.C., and Cleator, H.  Baffin Bay narwhal population distribution and numbers: Aerial surveys in the Canadian High Arctic, 2002-04.  Arctic 63(1): 85-99, 2010. 
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    Aerial surveys of narwhals (Monodon monoceros) were conducted in the Canadian High Arctic during the month of August from 2002 to 2004. The surveys covered the waters of Barrow Strait, Prince Regent Inlet, the Gulf of Boothia, Admiralty Inlet, Eclipse Sound, and the eastern coast of Baffin Island, using systematic sampling methods. Fiords were flown along a single transect down the middle. Near-surface population estimates increased by 1.9% - 8.7% when corrected for perception bias. The estimates were further increased by a factor of approximately 3, to account for individuals not seen because they were diving when the survey plane flew over (availability bias). These corrections resulted in estimates of 27 656 (SE = 14 939) for the Prince Regent and Gulf of Boothia area, 20 225 (SE = 7285) for the Eclipse Sound area, and 10 073 (SE = 3123) for the East Baffin Island fiord area. The estimate for the Admiralty Inlet area was 5362 (SE = 2681) but is thought to be biased. Surveys could not be done in other known areas of occupation, such as the waters of the Cumberland Peninsula of East Baffin, and channels farther west of the areas surveyed (Peel Sound, Viscount Melville Sound, Smith Sound and Jones Sound, and other channels of the Canadian Arctic archipelago). Despite these probable biases and the incomplete coverage, results of these surveys show that the summering range of narwhals in the Canadian High Arctic is vast. If narwhals are philopatric to their summering areas, as they appear to be, the total population of that range could number more than 60 000 animals. The largest numbers are in the western portion of their summer range, around Somerset Island, and also in the Eclipse Sound area. However, these survey estimates have large variances due to narwhal aggregation in some parts of the surveyed areas.

  • Kirkegaard, M., Sonne, C., Jakobsen, J., Jenssen, B.M., Letcher, R.J., and Dietz, R.  Organohalogens in a whale-blubber-supplemented diet affects hepatic retinol and renal tocopherol concentrations in Greenland sled dogs (Canis familiaris).  Journal of Toxicology and Environmental Health Part A 73(12): 773-786, 2010. 
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    The aim of this study was to examine the plasma, liver, and kidney status of vitamin A (retinol) and vitamin E (α-tocopherol) in two groups of Greenland sled dogs (Canis familiaris), with a total number of 16 bitches and 8 pups. The dogs were fed either minke whale (Balaenoptera acuterostrata) blubber (exposed dogs) or uncontaminated (control group) porcine fat for up to 12 to 21 mo of age. The daily intake of 50-200 g whale blubber (mean: 112 g) constituted between 10.4 and 11.7 µg/kg body weight ∑organohalogen contaminants (OHC) (or between 4.6 and 6.1 µg/kg body weight ∑polychlorinated biphenyls [PCB]). Retinol was approximately 18% and α-tocopherol 22% higher in the diet of the exposed dogs compared to controls. In adipose tissue, mean of ΣOHC was 92 ng/g lipid weight (lw) and 5005 ng/g lw for all control (n = 12) and exposed dogs (n = 10), respectively. Hepatic retinol correlated negatively with Σ-dichlorodiphenyldichloro-ethane (ΣDDT) and and Σ-polybrominated diphenyl ethers (ΣPBDE) for all exposed animals. A negative correlation between kidney α-tocopherol and ΣPCB concentrations was observed, whereas two positive significant correlations were observed between kidney retinol and Σ-chlordane-related compounds (ΣCHL) and dieldrin concentrations. Hepatic α-tocopherol concentrations were significantly lower in exposed compared to controls, most likely due to a combination by OHC exposure and high dietary intake of unsaturated fatty acids. These results suggest that dietary exposure from OHC may, even at low concentrations, possibly affect retinol and α-tocopherol status in Arctic top predators.

  • Fire, S.E., Wang, Z.H., Byrd, M., Whitehead, H.R., Paternoster, J., and Morton, S.L.  Co-occurrence of multiple classes of harmful algal toxins in bottlenose dolphins (Tursiops truncatus) stranding during an unusual mortality event in Texas, USA.  Harmful Algae 10(3): 330-336, 2011. 
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    During February-April 2008, an unusual mortality event occurred in Texas coastal waters that resulted in over 100 bottlenose dolphin (Tursiops truncatus) deaths. This mortality event overlapped spatially and temporally with a harmful algal bloom (HAB) composed of the toxin-producing genera Dinophysis spp. and Prorocentrum spp., and was associated with shellfish bed closures due to HAB toxins. A bloom of the toxin-producing diatom Pseudo-nitzschia pungens was also detected in Texas coastal waters in early April, towards the end of the dolphin mortality event. Analysis of dolphin gastrointestinal contents collected during this event demonstrated the presence of the HAB toxins domoic acid and okadaic acid in association with these blooms, as well as evidence of brevetoxin exposure in the absence of an associated K. brevis bloom. Historical dolphin stranding data for Texas waters indicate seasonal stranding peaks similar to the present study, indicating a need for investigating potential HAB involvement in mass strandings in previous years and in future events. This study marks the first reported occurrence of okadaic acid in marine mammals, and documents a unique co-occurrence of multiple HAB toxins associated with an unusual mortality event. Texas waters harbor a high diversity of HAB events relative to other coastal regions, and this study highlights the importance of efforts to understand the impacts of such HAB events on the health of Texas marine wildlife.

  • Moon, H.B., Kannan, K., Choi, H.G., An, Y.R., Choi, S.G., Park, J.Y., and Kim, Z.G.  Concentrations and accumulation features of PCDDs, PCDFs and dioxin-like PCBs in cetaceans from Korean coastal waters.  Chemosphere 79(7): 733-739, 2010. 
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    Despite several studies that report accumulation of polychlorinated biphenyls (PCBs) and DDT in marine mammals worldwide, very few have examined polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like PCBs. In particular, no earlier studies have reported concentrations and accumulation profiles of persistent organic pollutants (POPs) in marine mammals from Korea. In this study, concentrations and accumulation features of PCDD/Fs and dioxin-like PCBs were measured in liver and blubber of minke whales and long-beaked common dolphins collected from Korean coastal waters. The concentrations of PCDFs and dioxin-like PCBs in blubber were 3-10 times higher than the concentrations measured in liver, but PCDDs were higher in liver than blubber. Total toxic equivalent (TEQ) concentrations in blubber of minke whales and common dolphins from Korean coastal waters were similar to, or higher than those reported for cetaceans and seals from other countries. Homologue and congener profiles of PCDD/Fs were different between livers and blubbers, while the profiles of dioxin-like PCBs were similar between the tissues. Concentrations of PCDD/Fs and dioxin-like PCBs in liver and blubber of dolphins were significantly higher than those measured in whales, due to differences in habitat and diet. The relative contribution of individual chemical groups to total TEQs was different between the two cetacean species, suggesting different exposures and metabolic activity. The TEQ levels in minke whales did not exceed the threshold level suggested for immunomodulation, while TEQs in all dolphin samples exceeded the suggested threshold level, implying potential adverse health effects from exposure to PCDD/Fs and PCBs.

  • Stavros, H.C.W., Stolen, M., Durden, W.N., McFee, W., Bossart, G.D., and Fair, P.A.  Correlation and toxicological inference of trace elements in tissues from stranded and free-ranging bottlenose dolphins (Tursiops truncatus).  Chemosphere 82(11): 1649-1661, 2011. 
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    The significance of metal concentrations in marine mammals is not well understood and relating concentrations between stranded and free-ranging populations has been difficult. In order to predict liver concentrations in free-ranging dolphins, we examined concentrations of trace elements (Al, As, Ba, Be, Cd, Co, Cu, Fe, Li, Mn, Ni, Pb, Sb, Se, Sn, total Hg (THg), V, Zn) in skin and liver of stranded bottlenose dolphins (Tursiops truncatus) from the South Carolina (SC) coast and the Indian River Lagoon, Florida (FL) during 2000-2008. Significantly higher concentrations of Zn, Fe, Se, Al, Cu and THg were found in skin while liver exhibited significantly higher Cu, Fe, Mn and THg concentrations for both study sites. Mean skin concentrations of Cu and Mn were significantly higher in SC dolphins while higher concentrations of THg and V were found in FL dolphins. In addition, liver tissues in SC dolphins exhibited significantly higher As concentrations while higher Fe, Pb, Se, THg, and V levels were found in FL dolphins. Two elements (Cu and THg) showed significant age-related correlations with skin concentration while five elements (Cu. Se, THg, Zn and V) showed age-related correlations with liver concentrations. Geographic location influenced age-related accumulation of several trace elements and age-related accumulation of THg in hepatic tissue was observed for both sites to have the highest correlations (r2 = 0.90SC; r2 = 0.69FL). Mean THg concentration in liver was about 10 times higher in FL dolphins (330 µg g-1 dw) than those samples from SC dolphins (34.3 µg g-1 dw). The mean molar ratio of Hg to Se was 0.93 ± 0.32 and 1.08 ± 0.38 for SC and FL dolphins, respectively. However, the Hg:Se ratio varied with age as much lower ratios (0.2-0.4) were found in younger animals. Of the 18 measured elements, only THg was significantly correlated in skin and liver of stranded dolphins and skin of free-ranging dolphins from both sites suggesting that skin may be useful in predicting Hg concentrations in liver tissue of free-ranging dolphins. Results indicate that 33% of the stranded and 15% of the free-ranging dolphins from FL exceed the minimum 100 µg g-1 wet weight (ww) (~400 dw) Hg threshold for hepatic damage while none from SC reached this level. Hepatic concentrations of As in SC dolphins and V in FL dolphins were also highly correlated with skin concentrations which may have some regional specificity predictive value. The present study provides the first application of trace element concentrations derived from stranded bottlenose dolphins to predict liver concentrations in free-ranging populations.

  • Yordy, J.E., Mollenhauer, M.A.M., Wilson, R.M., Wells, R.S., Hohn, A., Sweeney, J., Schwacke, L.H., Rowles, T.K., Kucklick, J.R., and Peden-Adams, M.M.  Complex contaminant exposure in cetaceans: A comparative E-Screen analysis of bottlenose dolphin blubber and mixtures of four persistent organic pollutants.  Environmental Toxicology and Chemistry 29(10): 2143-2153, 2010. 
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    Cetaceans are federally protected species that are prone to accumulate complex mixtures of persistent organic pollutants (POPs), which individually may exert estrogenic or antiestrogenic effects. In the present study it was assessed whether contaminant mixtures harbored by cetaceans are estrogenic or antiestrogenic using a comparative approach. Interactions of antiestrogenic and estrogenic compounds were first investigated with the E-Screen assay using a mixture of four POPs (dichlorodiphenyldichloroethylene [4,4'-DDE], trans-nonachlor, and polychlorinated biphenyls [PCBs] 138 180) prevalent in cetacean blubber. Estrogenic/ antiestrogenic activity was determined for the individual compounds and their binary, tertiary, and quaternary combinations. Significantly different responses were observed for the various POP mixtures, including enhanced estrogenic and antiestrogenic effects and antagonistic interactions. These results were then compared to the concentrations and estrogenic/antiestrogenic activity of contaminant mixtures isolated directly from the blubber of 15 bottlenose dolphins (Tursiops truncatus) collected from five U.S. Atlantic and Gulf of Mexico locations. The lowest observed effect concentrations (LOECs) determined for 4,4'-DDE (20 µmol/L), PCB 138 (20 µmol/L), PCB 180 (21 µmol/L), and trans-nonachlor (3 µmol/L) in the E-Screen were greater than estimated dolphin blood concentrations. Although estimated blood concentrations were below the LOECs, significant estrogenic activity was detected in diluted dolphin blubber from Cape May, NJ and Bermuda. Positive correlations between blubber estrogenicity and select POP concentrations (ΣDDTs, ΣPBDEs, ΣHCB, Σestrogenic PCBs, Σestrogenic POPs) were also observed. Collectively, these results suggest that select bottlenose dolphin populations may be exposed to contaminants that act in concert to exert estrogenic effects at biologically relevant concentrations. These observations do not necessarily provide direct evidence of endocrine disruption; however, they may indicate an environmental source of xenoestrogenic exposure warranting future research.

  • Gerrodette, T., Taylor, B.L., Swift, R., Rankin, S., Jaramillo-Legorreta, A.M., and Rojas-Bracho, L.  A combined visual and acoustic estimate of 2008 abundance, and change in abundance since 1997, for the vaquita, Phocoena sinus.  Marine Mammal Science 27(2): E79-E100, 2011. 
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    A line-transect survey for the critically endangered vaquita, Phocoena sinus, was carried out in October-November 2008, in the northern Gulf of California, Mexico. Areas with deeper water were sampled visually from a large research vessel, while shallow water areas were covered by a sailboat towing an acoustic array. Total vaquita abundance in 2008 was estimated to be 245 animals (CV = 73%, 95% CI 68-884). The 2008 estimate was 57% lower than the 1997 estimate, an average rate of decline of 7.6%/yr. Bayesian analyses found an 89% probability of decline in total population size during the 11 yr period, and a 100% probability of decline in the central part of the range. Acoustic detections were assumed to represent porpoises with an average group size of 1.9, the same as visual sightings. Based on simultaneous visual and acoustic data in a calibration area, the probability of detecting vaquitas acoustically on the trackline was estimated to be 0.41 (CV = 108%). The Refuge Area for the Protection of the Vaquita, where gill net fishing is currently banned, contained approximately 50% of the population. While animals move in and out of the Refuge Area, on average half of the population remains exposed to bycatch in artisanal gill nets.

  • Gerrodette, T. and Rojas-Bracho, L.  Estimating the success of protected areas for the vaquita, Phocoena sinus.  Marine Mammal Science 27(2): E101-E125, 2011. 
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    Bycatch in artisanal gill nets threatens the vaquita, Phocoena sinus, with extinction. In 2008 the Mexican government announced a conservation action plan for this porpoise, with three options for a protected area closed to gill net fishing. The probability of success of each of the three options was estimated with a Bayesian population model, where success was defined as an increase in vaquita abundance after 10 yr. The model was fitted to data on abundance, bycatch, and fishing effort, although data were sparse and imprecise. Under the first protected area option, the existing Refuge Area for the Protection of the Vaquita, bycatch was about 7% of population size, and probability of success was 0.08. Under the second option with a larger protected area, the probability of success was 0.35. The third option was large enough to eliminate vaquita bycatch and had a probability of success >0.99. Probability of success was reduced if elimination of vaquita bycatch was delayed or incomplete. Despite considerable efforts by the Mexican government to support vaquita conservation, abundance will probably continue to decline unless additional measures to reduce vaquita bycatch are taken, such as banning gill nets within the vaquita's range and developing effective alternative fishing gear.

  • Williams, T.M., Noren, S.R., and Glenn, M.  Extreme physiological adaptations as predictors of climate-change sensitivity in the narwhal, Monodon monoceros.  Marine Mammal Science 27(2): 334-349, 2011. 
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    Rapid changes in sea ice cover associated with global warming are poised to have marked impacts on polar marine mammals. Here we examine skeletal muscle characteristics supporting swimming and diving in one polar species, the narwhal, and use these attributes to further document this cetacean's vulnerability to unpredictable sea ice conditions and changing ecosystems. We found that extreme morphological and physiological adaptations enabling year-round Arctic residency by narwhals limit behavioral flexibility for responding to alternations in sea ice. In contrast to the greyhound-like muscle profile of acrobatic odontocetes, the longissimus dorsi of narwhals is comprised of 86.8% ± 7.7% slow twitch oxidative fibers, resembling the endurance morph of human marathoners. Myoglobin content, 7.87 ± 1.72 g/100 g wet muscle, is one of the highest levels measured for marine mammals. Calculated maximum aerobic swimming distance between breathing holes in ice is <1,450 m, which permits routine use of only 2.6% - 10.4% of ice-packed foraging grounds in Baffin Bay. These first measurements of narwhal exercise physiology reveal extreme specialization of skeletal muscles for moving in a challenging ecological niche. This study also demonstrates the power of using basic physiological attributes to predict species vulnerabilities to environmental perturbation before critical population disturbance occurs.

  • Kanaji, Y., Okamura, H., and Miyashita, T.  Long-term abundance trends of the northern form of the short-finned pilot whale (Globicephala macrorhynchus) along the Pacific coast of Japan.  Marine Mammal Science 27(3): 477-492, 2011. 
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    The abundance of the northern form of the short-finned pilot whale, Globicephala macrorhynchus, in the Pacific waters of northern Japan was estimated from a line transect survey conducted in 2006 and data from seven previous surveys collected between 1985 and 1997. To overcome the difficulty of small sample size and inconsistency in survey design, we used an adjustment method using multiple covariates and sensitivity analysis by considering several scenarios. Abundance estimates showed similar long-term trends among scenarios. The northern form of G. macrorhynchus was more abundant in 1985 than in 1991-2006. The annual catch of the northern form of G. macrorhynchus exceeded the potential biological removal (PBR), especially in the 1980s. Thus, the commercial take in the early 1980s was suspected as a partial cause of a serious abundance decrease. These results provide valuable information for interpreting the impacts of coastal whaling, and to develop future management plans.

  • Baker, C.S., Steel, D., Choi, Y., Lee, H., Kim, K.S., Choi, S.K., Ma, Y.U., Hambleton, C., Psihoyos, L., Brownell, R.L., and Funahashi, N.  Genetic evidence of illegal trade in protected whales links Japan with the US and South Korea.  Biology Letters 6(5): 647-650, 2010.
    Open Access >>  
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    We report on genetic identification of 'whale meat' purchased in sushi restaurants in Los Angeles, CA (USA) in October 2009 and in Seoul, South Korea in June and September 2009. Phylogenetic analyses of mtDNA cytochrome b sequences confirmed that the products included three species of whale currently killed in the controversial scientific whaling programme of Japan, but which are protected from international trade: the fin, sei and Antarctic minke. The DNA profile of the fin whale sold in Seoul established a match to products purchased previously in Japan in September 2007, confirming unauthorized trade between these two countries. Following species identification, these products were handed over to the appropriate national or local authorities for further investigation. The illegal trade of products from protected species of whales, presumably taken under a national permit for scientific research, is a timely reminder of the need for independent, transparent and robust monitoring of any future whaling.

  • Parks, S.E., Johnson, M., Nowacek, D., and Tyack, P.L.  Individual right whales call louder in increased environmental noise.  Biology Letters 7(1): 33-35, 2011. 
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    The ability to modify vocalizations to compensate for environmental noise is critical for successful communication in a dynamic acoustic environment. Many marine species rely on sound for vital life functions including communication, navigation and feeding. The impacts of significant increases in ocean noise levels from human activities are a current area of concern for the conservation of marine mammals. Here, we document changes in calling behaviour by individual endangered North Atlantic right whales (Eubalaena glacialis) in increased background noise. Right whales, like several bird and primate species, respond to periods of increased noise by increasing the amplitude of their calls. This behaviour may help maintain the communication range with conspecifics during periods of increased noise. These call modifications have implications for conservation efforts for right whales, affecting both the way whales use sound to communicate and our ability to detect them with passive acoustic monitoring systems.

  • Wade, P.R., Kennedy, A., Leduc, R., Barlow, J., Carretta, J., Shelden, K., Perryman, W., Pitman, R., Robertson, K., Rone, B., Salinas, J.C., Zerbini, A., Brownell, R.L., and Clapham, P.J.  The world's smallest whale population?  Biology Letters 7(1): 83-85, 2011.
    Open Access >>  
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    The North Pacific right whale (Eubalaena japonica) was heavily exploited by both nineteenth century whaling and recent (1960s) illegal Soviet catches. Today, the species remains extremely rare especially in the eastern North Pacific. Here, we use photographic and genotype data to calculate the first mark-recapture estimates of abundance for right whales in the Bering Sea and Aleutian Islands. The estimates were very similar: photographic = 31 (95% CL 23-54), genotyping = 28 (95% CL 24-42). We also estimated the population contains eight females (95% CL 7-18) and 20 males (95% CL 17-37). Although these estimates may relate to a Bering Sea subpopulation, other data suggest that the total eastern North Pacific population is unlikely to be much larger. Its precarious status today – the world's smallest whale population for which an abundance estimate exists – is a direct consequence of uncontrolled and illegal whaling, and highlights the past failure of international management to prevent such abuses.

  • Mellinger, D.K., Nieukirk, S.L., Klinck, K., Klinck, H., Dziak, R.P., Clapham, P.J., and Brandsdóttir, B.  Confirmation of right whales near a nineteenth-century whaling ground east of southern Greenland.  Biology Letters 7(3): 411-413, 2011. 
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    North Atlantic right whales (Eubalaena glacialis) were found in an important nineteenth century whaling area east of southern Greenland, from which they were once thought to have been extirpated. In 2007-2008, a 1-year passive acoustic survey was conducted at five sites in and near the 'Cape Farewell Ground', the former whaling ground. Over 2000 right whale calls were recorded at these sites, primarily during July-November. Most calls were northwest of the historic ground, suggesting a broader range in this region than previously known. Geographical and temporal separation of calls confirms use of this area by multiple animals.

  • Van Waerebeek, K., Leaper, R., Baker, A.N., Papastavrou, V., Thiele, D., Findlay, K., Donovan, G., and Ensor, P.  Odontocetes of the Southern Ocean Sanctuary.  Journal of Cetacean Research and Management 11(3): 315-346, 2010. 
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    Twenty-eight odontocete species were identified as occupying sub-Antarctic and Antarctic habitat covered by the 1994 IWC-established Southern Ocean Sanctuary. Toothed whales evidently play an important part in the Antarctic polar ecosystem. Twenty-two species are autochthonous in showing a regular, apparently year-round, presence in the Sanctuary: Physeter macrocephalus, Kogia breviceps, Orcinus orca, Globicephala melas edwardii, Pseudorca crassidens, Lagenorhynchus cruciger, Lagenorhynchus obscurus, Lissodelphis peronii, Cephalorhynchus commersonii, Cephalorhynchus hectori, Tursiops truncatus, Delphinus delphis, Phocoena dioptrica, Hyperoodon planifrons, Berardius arnuxii, Ziphius cavirostris, Tasmacetus shepherdi, Mesoplodon layardii, Mesoplodon traversii, Mesoplodon grayi, Mesoplodon bowdoini and Mesoplodon hectori. Six species are considered vagrants into the Sanctuary: Kogia sima, Grampus griseus, Steno bredanensis, Mesoplodon peruvianus, Mesoplodon densirostris and Mesoplodon mirus. However, vagrant status of these three mesoplodonts is only provisionally assigned, considering that improved knowledge of diagnostic features of beaked whales should, as in recent years, continue to facilitate at-sea identification. Two species are considered as having a 'contiguous' range (records less than 2° north of Sanctuary boundaries): Mesoplodon ginkgodens (at 39°S) and Mesoplodon mirus (at 38°24'S). The habitual southern range of at least four odontocetes extends significantly farther poleward than expected. G. melas edwardii is regularly encountered south of the Antarctic Polar Front, much like M. grayi which is known to reach the Ross Sea ice edge (ca. 67°S). Z. cavirostris and L. obscurus cross the Polar Front occasionally. The distribution of M. peruvianus and M. traversii and their relation to SST are unclear. Their southernmost records, 42°31'S and 44°17'S respectively, may either be extralimital or, more likely, reflect ordinary austral range. Temporally non-aligned distribution patterns of  Hyperoodon planifrons in Antarctic and South African waters may suggest stock segregation.

  • Weijs, L., van Elk, C., Das, K., Blust, R., and Covaci, A.  Persistent organic pollutants and methoxylated PBDEs in harbour porpoises from the North Sea from 1990 until 2008. Young wildlife at risk?  The Science of the Total Environment 409(1): 228-237, 2010. 
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    In the European North Sea, harbour porpoises are top predators with relatively long life spans and a limited capacity for metabolic biotransformation of contaminants compared to some other marine mammal species. As such, they are exposed to a mixture of persistent pollutants, such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), DDT and metabolites (DDXs), hexachlorobenzene (HCB) and chlordanes (CHLs) that bioaccumulate in their tissues. We report here on the levels of persistent organic pollutants and of the naturally-produced methoxylated PBDEs (MeO-PBDEs) in blubber, liver and kidney of harbour porpoise neonates (n = 3), calves (n = 15), juveniles (n = 6) and adults (n = 4) of the southern North Sea. Concentrations of almost all contaminant classes decrease slightly in all age groups over the period 1990-2008. For some classes (e.g. PCBs and DDXs) however, levels seem to increase little in harbour porpoise calves. In all animals, blubber had the highest concentrations, followed by liver and kidney, whereas liver and kidney were the preferred tissues for several compounds, such as octa- and deca-PCBs. Our data suggest that harbour porpoises calves are exposed to higher or comparable concentrations of POPs and of MeO-PBDEs and somewhat different patterns of selected POPs than adults, potentially placing them, and the entire population, at a disproportionate risk for exposure-related health effects.

  • Pershing, A.J., Christensen, L.B., Record, N.R., Sherwood, G.D., and Stetson, P.B.  The impact of whaling on the ocean carbon cycle: Why bigger was better.  PLoS ONE 5(8): art. e12444, 2010.
    Open Access >>  
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    Background  Humans have reduced the abundance of many large marine vertebrates, including whales, large fish, and sharks, to only a small percentage of their pre-exploitation levels. Industrial fishing and whaling also tended to preferentially harvest the largest species and largest individuals within a population. We consider the consequences of removing these animals on the ocean's ability to store carbon. Methodology/Principal Findings  Because body size is critical to our arguments, our analysis focuses on populations of baleen whales. Using reconstructions of pre-whaling and modern abundances, we consider the impact of whaling on the amount of carbon stored in living whales and on the amount of carbon exported to the deep sea by sinking whale carcasses. Populations of large baleen whales now store 9.1×106 tons less carbon than before whaling. Some of the lost storage has been offset by increases in smaller competitors; however, due to the relative metabolic efficiency of larger organisms, a shift toward smaller animals could decrease the total community biomass by 30% or more. Because of their large size and few predators, whales and other large marine vertebrates can efficiently export carbon from the surface waters to the deep sea. We estimate that rebuilding whale populations would remove 1.6×105 tons of carbon each year through sinking whale carcasses. Conclusions/Significance Even though fish and whales are only a small portion of the ocean's overall biomass, fishing and whaling have altered the ocean's ability to store and sequester carbon. Although these changes are small relative to the total ocean carbon sink, rebuilding populations of fish and whales would be comparable to other carbon management schemes, including ocean iron fertilization.

  • Mendez, M., Rosenbaum, H.C., Wells, R.S., Stamper, A., and Bordino, P.  Genetic evidence highlights potential impacts of by-catch to cetaceans.  PLoS ONE 5(12): art. e15550, 2010.
    Open Access >>  
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    Incidental entanglement in fishing gear is arguably the most serious threat to many populations of small cetaceans, judging by the alarming number of captured animals. However, other aspects of this threat, such as the potential capture of mother-offspring pairs or reproductive pairs, could be equally or even more significant but have rarely been evaluated. Using a combination of demographic and genetic data we provide evidence that i) Franciscana dolphin pairs that are potentially reproductive and mother-offspring pairs form temporal bonds, and ii) are entangled simultaneously. Our results highlight potential demographic and genetic impacts of by-catch to cetacean populations: the joint entanglement of mother-offspring or reproductive pairs, compared to random individuals, might exacerbate the demographic consequences of by-catch, and the loss of groups of relatives means that significant components of genetic diversity could be lost together. Given the social nature of many odontocetes (toothed cetaceans), we suggest that these potential impacts could be rather general to the group and therefore by-catch could be more detrimental than previously considered.

  • Twiner, M.J., Fire, S., Schwacke, L., Davidson, L., Wang, Z., Morton, S., Roth, S., Balmer, B., Rowles, T.K., and Wells, R.S.  Concurrent exposure of bottlenose dolphins (Tursiops truncatus) to multiple algal toxins in Sarasota Bay, Florida, USA.  PLoS ONE 6(3): art. e17394, 2011.
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    Sentinel species such as bottlenose dolphins (Tursiops truncatus) can be impacted by large-scale mortality events due to exposure to marine algal toxins. In the Sarasota Bay region (Gulf of Mexico, Florida, USA), the bottlenose dolphin population is frequently exposed to harmful algal blooms (HABs) of Karenia brevis and the neurotoxic brevetoxins (PbTx; BTX) produced by this dinoflagellate. Live dolphins sampled during capture-release health assessments performed in this region tested positive for two HAB toxins; brevetoxin and domoic acid (DA). Over a ten-year study period (2000-2009) we have determined that bottlenose dolphins are exposed to brevetoxin and/or DA on a nearly annual basis (i.e., DA: 2004, 2005, 2006, 2008, 2009; brevetoxin: 2000, 2004, 2005, 2008, 2009) with 36% of all animals testing positive for brevetoxin (n = 118) and 53% positive for DA (n = 83) with several individuals (14%) testing positive for both neurotoxins in at least one tissue/fluid. To date there have been no previously published reports of DA in southwestern Florida marine mammals, however the May 2008 health assessment coincided with a Pseudo-nitzschia pseudodelicatissima bloom that was the likely source of DA observed in seawater and live dolphin samples. Concurrently, both DA and brevetoxin were observed in common prey fish. Although no Pseudo-nitzschia bloom was identified the following year, DA was identified in seawater, fish, sediment, snails, and dolphins. DA concentrations in feces were positively correlated with hematologic parameters including an increase in total white blood cell (p = 0.001) and eosinophil (p < 0.001) counts. Our findings demonstrate that dolphins within Sarasota Bay are commonly exposed to two algal toxins, and provide the impetus to further explore the potential long-term impacts on bottlenose dolphin health.

  • Tyack, P. L. et alBeaked whales respond to simulated and actual navy sonar.  PLoS ONE 6(3): art. e17009, 2011.
    Open Access >>  
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    Beaked whales have mass stranded during some naval sonar exercises, but the cause is unknown. They are difficult to sight but can reliably be detected by listening for echolocation clicks produced during deep foraging dives. Listening for these clicks, we documented Blainville's beaked whales, Mesoplodon densirostris, in a naval underwater range where sonars are in regular use near Andros Island, Bahamas. An array of bottom-mounted hydrophones can detect beaked whales when they click anywhere within the range. We used two complementary methods to investigate behavioral responses of beaked whales to sonar: an opportunistic approach that monitored whale responses to multi-day naval exercises involving tactical mid-frequency sonars, and an experimental approach using playbacks of simulated sonar and control sounds to whales tagged with a device that records sound, movement, and orientation. Here we show that in both exposure conditions beaked whales stopped echolocating during deep foraging dives and moved away. During actual sonar exercises, beaked whales were primarily detected near the periphery of the range, on average 16 km away from the sonar transmissions. Once the exercise stopped, beaked whales gradually filled in the center of the range over 2-3 days. A satellite tagged whale moved outside the range during an exercise, returning over 2-3 days post-exercise. The experimental approach used tags to measure acoustic exposure and behavioral reactions of beaked whales to one controlled exposure each of simulated military sonar, killer whale calls, and band-limited noise. The beaked whales reacted to these three sound playbacks at sound pressure levels below 142 dB re 1 µPa by stopping echolocation followed by unusually long and slow ascents from their foraging dives. The combined results indicate similar disruption of foraging behavior and avoidance by beaked whales in the two different contexts, at exposures well below those used by regulators to define disturbance.

  • Park, B.K., Park, G.J., An, Y.R., Choi, H.G., Kim, G.B., and Moon, H.B.  Organohalogen contaminants in finless porpoises (Neophocaena phocaenoides) from Korean coastal waters: Contamination status, maternal transfer and ecotoxicological implications.  Marine Pollution Bulletin 60(5): 768-774, 2010. 
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    Information on the occurrence of organochlorine compounds (OCs) and polybrominated diphenyl ethers (PBDEs) in marine mammals from Korea is scarce. In this study, OCs and PBDEs were determined in the blubber of 52 finless porpoises (Neophocaena phocaenoides) from Korean coastal waters. The highest contamination was found for DDTs, followed by PCBs, PBDEs, HCHs, CHLs and HCB. Concentrations of OCs in finless porpoises were lower than those reported worldwide, but PBDE contamination was comparable to other studies, due to ongoing use of PBDE products in Korea. Significant gender-specific differences were found for concentrations and accumulation profiles of OCs and PBDEs, due to maternal transfer and lactation of mature females. The BDEs 49 and 66 comprised 4-16% of total PBDEs in finless porpoises, which seems to be associated with debromination of higher BDEs. The DDT levels in Korean finless porpoises have almost reached the levels associated with immunosuppression in marine mammals.

  • Thompson, P.M., Lusseau, D., Barton, T., Simmons, D., Rusin, J., and Bailey, H.  Assessing the responses of coastal cetaceans to the construction of offshore wind turbines.  Marine Pollution Bulletin 60(8): 1200-1208, 2010. 
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    The expansion of offshore renewables has raised concerns over potential disturbance to coastal cetaceans. In this study, we used passive acoustic monitoring to assess whether cetaceans responded to pile-driving noise during the installation of two 5 MW offshore wind turbines off NE Scotland in 2006. Monitoring was carried out at both the turbine site and a control site in 2005, 2006 and 2007. Harbour porpoises occurred regularly around the turbine site in all years, but there was some evidence that porpoises did respond to disturbance from installation activities. We use these findings to highlight how uncertainty over cetacean distribution and the scale of disturbance effects constrains opportunities for B-A-C-I studies. We explore alternative approaches to assessing the impact of offshore wind farm upon cetaceans, and make recommendations for the research and monitoring that will be required to underpin future developments.

  • Dolman, S.J., Parsons, E.C.M., and Wright, A.J.  Cetaceans and military sonar: A need for better management.  Marine Pollution Bulletin 63(1-4): 1-4, 2011.
  • Wright, A.J., Deak, T., and Parsons, E.C.M.  Size matters: Management of stress responses and chronic stress in beaked whales and other marine mammals may require larger exclusion zones.  Marine Pollution Bulletin 63(1-4): 5-9, 2011.
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    Marine mammal management traditionally focuses on lethal takes, but non-lethal (or not immediately lethal) impacts of human disturbance, such as prolonged or repeated activation of the stress response, can also have serious conservation implications. The physiological stress response is a life-saving combination of systems and events that maximises the ability of an animal to kill or avoid being killed. However, "chronic stress" is linked to numerous conditions in humans, including coronary disease and infertility. Through examples, including beaked whales and sonar exposure, we discuss increasing human disturbance, mal-adaptive stress responses and chronic stress. Deep-diving and coastal species, and those targeted by whalewatching, may be particularly vulnerable. The various conditions linked with chronic stress in humans would have troubling implications for conservation efforts in endangered species, demands management attention, and may partly explain why some species have not recovered after protective measures (e.g., smaller protected areas) have been put into place.

  • Dolman, S.J., Evans, P.G.H., Notarbartolo-di-Sciara, G., and Frisch, H.  Active sonar, beaked whales and European regional policy.  Marine Pollution Bulletin 63(1-4): 27-34, 2011.
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    Various reviews, resolutions and guidance from international and regional fora have been produced in recent years that acknowledge the significance of marine noise and its potential impacts on cetaceans. Within Europe, ACCOBAMS and ASCOBANS have shown increasing attention to the issue. The literature highlights concerns surrounding the negative impacts of active sonar on beaked whales in particular, where concerns primarily relate to the use of mid-frequency active sonar (1-10 kHz), as used particularly in military exercises. The authors review the efforts that European regional policies have undertaken to acknowledge and manage possible negative impacts of active sonar and how these might assist the transition from scientific research to policy implementation, including effective management and mitigation measures at a national level.

  • Zirbel, K., Balint, P., and Parsons, E.C.M.  Navy sonar, cetaceans and the US Supreme Court: A review of cetacean mitigation and litigation in the US.  Marine Pollution Bulletin 63(1-4): 40-48, 2011.
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    One source of anthropogenic noise in the oceans which has attracted much concern is naval sonar. As a result of possible impacts of such sonar, several environmental NGOs have pursued legal cases in the United States criticizing environmental assessments conducted prior to exercises and proposed mitigation measures. Cases have been brought using the US National Environmental Protection Act, Marine Mammal Protection Act, Endangered Species Act, Coastal Zone Management Act and other statutes. This paper reviews the chronology and results of these various cases. During the G.W. Bush presidential administration, the legal battle went to the US Supreme Court in the case Winter vs. Natural Resources Defense Council. This case however, did not address the potential impacts of sonar on cetaceans or the effectiveness of mitigation measures. During the Obama administration, mitigation measures for naval exercises have been revised, and working groups planned, in an attempt to resolve conflict between parties.

  • Abate, R.S.  NEPA, national security, and ocean noise: The past, present, and future of regulating the impact of navy sonar on marine mammals.  Journal of International Wildlife Law and Policy 13(4): 326-356, 2010.
  • Martinez-Levasseur, L.M., Gendron, D., Knell, R.J., O'Toole, E.A., Singh, M., and Acevedo-Whitehouse, K.  Acute sun damage and photoprotective responses in whales.  Proceedings of the Royal Society of London [B] 278(1711): 1581-1586, 2011.
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    Rising levels of ultraviolet radiation (UVR) secondary to ozone depletion are an issue of concern for public health. Skin cancers and intraepidermal dysplasia are increasingly observed in individuals that undergo chronic or excessive sun exposure. Such alterations of skin integrity and function are well established for humans and laboratory animals, but remain unexplored for mammalian wildlife. However, effects are unlikely to be negligible, particularly for species such as whales, whose anatomical or life-history traits force them to experience continuous sun exposure. We conducted photographic and histological surveys of three seasonally sympatric whale species to investigate sunburn and photoprotection. We find that lesions commonly associated with acute severe sun damage in humans are widespread and that individuals with fewer melanocytes have more lesions and less apoptotic cells. This suggests that the pathways used to limit and resolve UVR-induced damage in humans are shared by whales and that darker pigmentation is advantageous to them. Furthermore, lesions increased significantly in time, as would be expected under increasing UV irradiance. Apoptosis and melanocyte proliferation mirror this trend, suggesting that whales are capable of quick photoprotective responses. We conclude that the thinning ozone layer may pose a risk to the health of whales and other vulnerable wildlife.

  • Gedamke, J., Gales, N., and Frydman, S.  Assessing risk of baleen whale hearing loss from seismic surveys: The effect of uncertainty and individual variation.  Journal of the Acoustical Society of America 129(1): 496-506, 2011.
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    The potential for seismic airgun "shots" to cause acoustic trauma in marine mammals is poorly understood. There are just two empirical measurements of temporary threshold shift (TTS) onset levels from airgun-like sounds in odontocetes. Considering these limited data, a model was developed examining the impact of individual variability and uncertainty on risk assessment of baleen whale TTS from seismic surveys. In each of 100 simulations: 10 000 "whales" are assigned TTS onset levels accounting for: inter-individual variation; uncertainty over the population's mean; and uncertainty over weighting of odontocete data to obtain baleen whale onset levels. Randomly distributed whales are exposed to one seismic survey passage with cumulative exposure level calculated. In the base scenario, 29% of whales (5th/95th percentiles of 10%/62%) approached to 1-1.2 km range were exposed to levels sufficient for TTS onset. By comparison, no whales are at risk outside 0.6 km when uncertainty and variability are not considered. Potentially "exposure altering" parameters (movement, avoidance, surfacing, and effective quiet) were also simulated. Until more research refines model inputs, the results suggest a reasonable likelihood that whales at a kilometer or more from seismic surveys could potentially be susceptible to TTS and demonstrate the large impact uncertainty and variability can have on risk assessment.

  • Heide-Jorgensen, M.P., Laidre, K.L., Burt, M.L., Borchers, D.L., Marques, T.A., Hansen, R.G., Rasmussen, M., and Fossette, S.  Abundance of narwhals (Monodon monoceros) on the hunting grounds in Greenland.  Journal of Mammalogy 91(5): 1135-1151, 2010.
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    Narwhals (Monodon monoceros  L.) occur in the Atlantic sector of the Arctic where for centuries they have been subject to subsistence hunting by Inuit in Greenland and Canada. Scientific advice on the sustainable levels of removals from narwhal populations provides the basis for quotas implemented in both Greenland and Canada. The scientific advice relies heavily on extensive aerial surveys that are the only feasible way to acquire data on narwhal densities and abundance throughout their range. In some areas lack of information on abundance, in combination with high exploitation levels, has caused conservation concerns leading to restrictions on the international trade in narwhal tusks. Narwhals also are regarded as highly sensitive to habitat disturbance caused by global warming. This study analyzed data from aerial sighting surveys covering four major narwhal hunting grounds in Greenland. The surveys were conducted as double observer experiments with 2 independent observation platforms, 1 at the front and 1 at the rear of the survey plane. The sighting data were analyzed using mark recapture distance sampling techniques that allow for correction for whales that were missed by the observers. The surveys also were corrected for animals that were submerged during the passage of the survey plane, using diving and submergence data from satellite-linked time depth recorders deployed on 2 free-ranging narwhals. The abundance of narwhals on the wintering ground in West Greenland in 2006 was 7,819 (95% confidence interval [CI]: 4,358-14,029). The abundances of narwhals in Inglefield Bredning and Melville Bay, northwest Greenland in 2007 were 8,368 (95% CI: 5,209-13,442) and 6,024 (95% CI: 1,403-25,860), respectively. The abundance of narwhals in East Greenland in 2008 was 6,444 (95% CI: 2,505-16,575). These surveys provide the first estimates of narwhal abundance from important hunting areas in East and West Greenland and provide larger and more complete estimates from previously surveyed hunting grounds in Inglefield Bredning. The estimates can be used for setting catch limits for the narwhal harvest in West and East Greenland and as a baseline for examining the effects of climate change on narwhal abundance.

  • Tzika, A.C., D'Amico, E., Alfaro-Shigueto, J., Mangel, J.C., Van Waerebeek, K., and Milinkovitch, M.C.  Molecular identification of small cetacean samples from Peruvian fish markets.  Conservation Genetics 11(6): 2207-2218, 2010.
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    In the last 60 years, incidental entanglement in fishing gears (so called by-catch) became the main cause of mortality worldwide for small cetaceans and is pushing several populations and species to the verge of extinction. Thus, monitoring and quantifying by-catches is an important step towards proper and sustainable management of cetacean populations. Continuous studies indicated that by-catches and directed takes of small cetaceans in Peru greatly increased since 1985. Legal measures banning cetacean takes, enforced in 1994 and 1996, ironically made monitoring highly problematic as fishers continue catching these animals but utilize or dispose of carcasses clandestinely. Hence, in locations where cetaceans are landed covertly or already butchered, molecular genetic methods can provide the only means of identification of the species, sex, and sometimes the population of each sample. Here, we generate and analyse a fragment of the mitochondrial DNA cytochrome b gene and 5 nuclear microsatellite markers from 182 meat and skin samples of unidentified small cetaceans collected at three Peruvian markets between July 2006 and April 2007. Our results, compared to past surveys, indicate that Lagenorhynchus obscurus, Phocoena spinipinnis, Tursiops truncatus, Delphinus capensis, and D. delphis continue to be caught and marketed, but that the relative incidence of P. spinipinnis is highly reduced, possibly because of population depletion. The small number of possible sampling duplicates demonstrates that a high monitoring frequency is required for a thorough evaluation of incidental catches in the area. A wide public debate on by-catch mitigation measures is greatly warranted in Peru.

  • Fernandez-Contreras, M.M., Cardona, L., Lockyer, C.H., and Aguilar, A.  Incidental bycatch of short-beaked common dolphins (Delphinus delphis) by pairtrawlers off northwestern Spain.  ICES Journal of Marine Science 67(8): 1732-1738, 2010.
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    The numbers of short-beaked common dolphins captured annually by pairtrawlers operating off Galicia (northwestern Spain) and the operational factors influencing the bycatch were evaluated using on-board observations. Hauling time, fishing depth, and season of the year were identified as the key factors involved in the incidental capture. The dolphins were most vulnerable to trawls at night from May to September, around the continental shelf break. Most of the dolphins in the bycatch were males, and the average age was 13.4 ± 4.4 years for males and 11.5 ± 4.8 years for females. The sex ratio was male-biased owing to a few capture events involving several males each, supporting the notion that bachelor groups exist in the area. The annual bycatch in 2001 and 2002 was an estimated 394 dolphins [95% confidence interval (CI) 230–632], most taken from May to September (mean 348 dolphins, 95% CI 200–590) and just a few from October to April (mean 46 dolphins, 95% CI 0–132). This level of bycatch could be reduced significantly if trawlers were restricted to operating in water deeper than 250 m and likely avoided entirely if they were restricted to water deeper than 300 m.

  • Ainley, D.G.  A history of the exploitation of the Ross Sea, Antarctica.  Polar Record 46(238): 233-243, 2010.
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    Recent analyses of anthropogenic impacts on marine systems have shown that the Ross Sea is the least affected stretch of ocean on Earth, although historical effects were not included in those studies. Herein the literature is reviewed in order to quantify the extent of extraction of biological resources from the Ross Sea continental shelf and slope from the start of the 20th century. There was none before that time. An intense extraction of Weddell seals Leptonychotes weddellii by the expeditions of the 'heroic' period and then by New Zealand to feed sled dogs in the 1950-1980s caused the McMurdo Sound population to decrease permanently. Otherwise no other sealing occurred. Blue whales Balaenoptera musculus intermedia were extirpated from waters of the shelf break front during the 1920s, and have not reappeared. Minke whales B. bonaerensis probably expanded into the blue whale vacated habitat, but were then hunted during the 1970-1980s; their population has since recovered. Some minke whales are now taken in 'scientific whaling', twice more from the slope compared to the shelf. Other hunted cetaceans never occurred over the shelf and very few ever occurred in slope waters, and therefore their demise from whaling does not apply to the Ross Sea. No industrial fishing occurred in the Ross Sea until the 1996-1997 summer, when a fishery for Antarctic toothfish Dissostichus mawsoni was initiated, especially along the slope. This fishery has grown since then with effects on the ecosystem recently becoming evident. There is probably no other ocean area where the details of biological exploitation can be so elucidated. It appears that the Ross Sea continental shelf remains the least affected of any on the globe. However the same cannot be said of the slope.

  • Boertmann, D. and Nielsen, R.D.  A bowhead whale calf observed in northeast Greenland waters.  Polar Record 46(239): 373-375, 2010.
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    A bowhead whale mother and calf pair was recorded off the northeast Greenland coast in July 2009. This is apparently the first calf observed in the Spitsbergen stock of the bowhead whale since 1981.

  • Yordy, J.E., Wells, R.S., Balmer, B.C., Schwacke, L.H., Rowles, T.K., and Kucklick, J.R.  Partitioning of persistent organic pollutants between blubber and blood of wild bottlenose dolphins: Implications for biomonitoring and health.  Environmental Science and Technology 44(12): 4789-4795, 2010.
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    Biomonitoring surveys of wild cetaceans commonly utilize blubber as a means to assess exposure to persistent organic pollutants (POPs), but the relationship between concentrations in blubber and those in blood, a better indicator of target organ exposure, is poorly understood. To define this relationship, matched blubber and plasma samples (n = 56) were collected from free-ranging bottlenose dolphins (Tursiops truncatus) and analyzed for 61 polychlorinated biphenyl (PCB) congeners, 5 polybrominated diphenyl ether (PBDE) congeners, and 13 organochlorine pesticides (OCPs). With the exception of PCB 209, lipid-normalized concentrations of the major POPs in blubber and plasma were positively and significantly correlated (R2 = 0.828 to 0.976). Plasma concentrations, however, significantly increased with declining blubber lipid content, suggesting that as lipid is utilized, POPs are mobilized into blood. Compound- and homologue-specific blubber/blood partition coefficients also differed according to lipid content, suggesting POPs are selectively mobilized from blubber. Overall, these results suggest that with the regression parameters derived here, blubber may be used to estimate blood concentrations and vice versa. Additionally, the mobilization of lipid from blubber and concomitant increase in contaminants in blood suggests cetaceans with reduced blubber lipid may be at greater risk for contaminant-associated health effects.

  • Kucklick, J., Schwacke, L., Wells, R., Hohn, A., Guichard, A., Yordy, J., Hansen, L., Zolman, E., Wilson, R., Litz, J., Nowacek, D., Rowles, T., Pugh, R., Balmer, B., Sinclair, C., and Rosel, P.  Bottlenose dolphins as indicators of persistent organic pollutants in the western North Atlantic Ocean and northern Gulf of Mexico.  Environmental Science and Technology 45(10): 4270-4277, 2011.
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    Persistent organic pollutants (POPs) including legacy POPs (PCBs, chlordanes, mirex, DDTs, HCB, and dieldrin) and polybrominated diphenyl ether (PBDE) flame retardants were determined in 300 blubber biopsy samples from coastal and near shore/estuarine male bottlenose dolphins ( Tursiops truncatus) sampled along the U.S. East and Gulf of Mexico coasts and Bermuda. Samples were from 14 locations including urban and rural estuaries and near a Superfund site (Brunswick, Georgia) contaminated with the PCB formulation Aroclor 1268. All classes of legacy POPs in estuarine stocks varied significantly (p < 0.05) among sampling locations. POP profiles in blubber varied by location with the most characteristic profile observed in bottlenose dolphins sampled near the Brunswick and Sapelo estuaries along the Georgia coast which differed significantly (p < 0.001) from other sites. Here and in Sapelo, PCB congeners from Aroclor 1268 dominated indicating widespread food web contamination by this PCB mixture. PCB 153, which is associated with non-Aroclor 1268 PCB formulations, correlated significantly to human population indicating contamination from a general urban PCB source. Factors influencing regional differences of other POPs were less clear and warrant further study. This work puts into geographical context POP contamination in dolphins to help prioritize efforts examining health effects from POP exposure in bottlenose dolphins.

  • Pitman, R.L., Durban, J.W., Greenfelder, M., Guinet, C., Jorgensen, M., Olson, P.A., Plana, J., Tixier, P., and Towers, J.R.  Observations of a distinctive morphotype of killer whale (Orcinus orca), type D, from subantarctic waters.  Polar Biology 34(2): 303-306, 2011.
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    Studies have shown that killer whale ( Orcinus orca) communities in high latitudes regularly comprise assemblages of sympatric 'ecotypes' – forms that differ in morphology, behavior, and prey preferences. Although they can appear superficially similar, recent genetic evidence suggests that breeding is assortative among ecotypes within individual communities, and species-level divergences are inferred in some cases. Here, we provide information on a recently recognized 'type D' killer whale based on photographs of a 1955 mass stranding in New Zealand and our own six at-sea sightings since 2004. It is the most distinctive-looking form of killer whale that we know of, immediately recognizable by its extremely small white eye patch. Its geographic range appears to be circumglobal in subantarctic waters between latitudes 40ºS and 60ºS. School sizes are relatively large (mean 17.6; range 9-35; n = 7), and although nothing is known about the type D diet, it is suspected to include fish because groups have been photographed around longline vessels where they reportedly depredate Patagonian toothfish (Dissostichus eleginoides).

  • Matthews, C.J.D., Luque, S.P., Petersen, S.D., Andrews, R.D., and Ferguson, S.H.  Satellite tracking of a killer whale (Orcinus orca) in the eastern Canadian Arctic documents ice avoidance and rapid, long-distance movement into the North Atlantic.  Polar Biology 34(7): 1091-1096, 2011.
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    Killer whales (Orcinus orca ) occur in the eastern Canadian Arctic during the open-water season, but their seasonal movements in Arctic waters and overall distribution are poorly understood. During August 2009, satellite transmitters were deployed onto two killer whales in Admiralty Inlet, Baffin Island, Canada. A whale tracked for 90 days remained in Admiralty and Prince Regent Inlets from mid-August until early October, when locations overlapped aggregations of marine mammal prey species. While in Admiralty and Prince Regent Inlets, the whale traveled 96.1 ± 45.3 km day-1 (max 162.6 km day-1) and 120.1 ± 44.5 km day-1 (max 192.7 km day-1), respectively. Increasing ice cover in Prince Regent Inlet in late September and early October was avoided, and the whale left the region prior to heavy ice formation. The whale traveled an average of 159.4 ± 44.8 km day-1 (max 252.0 km day-1) along the east coast of Baffin Island and into the open North Atlantic by mid-November, covering over 5,400 km in approximately one month. This research marks the first time satellite telemetry has been used to study killer whale movements in the eastern Canadian Arctic and documents long-distance movement rarely observed in this species.

  • Williams, R., Gero, S., Bejder, L., Calambokidis, J., Kraus, S.D., Lusseau, D., Read, A.J., and Robbins, J.  Underestimating the damage: interpreting cetacean carcass recoveries in the context of the Deepwater Horizon/BP incident.  Conservation Letters 4(3): 228-233, 2011.
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    Evaluating impacts of human activities on marine ecosystems is difficult when effects occur out of plain sight. Oil spill severity is often measured by the number of marine birds and mammals killed, but only a small fraction of carcasses are recovered. The Deepwater Horizon/BP oil spill in the Gulf of Mexico was the largest in the U.S. history, but some reports implied modest environmental impacts, in part because of a relatively low number (101) of observed marine mammal mortalities. We estimate historical carcass-detection rates for 14 cetacean species in the northern Gulf of Mexico that have estimates of abundance, survival rates, and stranding records. This preliminary analysis suggests that carcasses are recovered, on an average, from only 2% (range: 0-6.2%) of cetacean deaths. Thus, the true death toll could be 50 times the number of carcasses recovered, given no additional information. We discuss caveats to this estimate, but present it as a counterpoint to illustrate the magnitude of misrepresentation implicit in presenting observed carcass counts without similar qualification. We urge methodological development to develop appropriate multipliers. Analytical methods are required to account explicitly for low probability of carcass recovery from cryptic mortality events (e.g., oil spills, ship strikes, bycatch in unmonitored fisheries and acoustic trauma).

  • Scheinin, A.P., Kerem, D., MacLeod, C.D., Gazo, M., Chicote, C.A., and Castellote, M.  Gray whale (Eschrichtius robustus) in the Mediterranean Sea: anomalous event or early sign of climate-driven distribution change.  Marine Biodiversity Records 4: art. e28, 2011.
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    On 8 May 2010, a gray whale was sighted off the Israeli Mediterranean shore and twenty-two days later, the same individual was sighted in Spanish Mediterranean waters. Since gray whales were last recorded in the North Atlantic in the 1700s, these sightings prompted much speculation about this whale's population origin. Here, we consider three hypotheses for the origin of this individual: (1) it represents a vagrant individual from the larger extant population of gray whales found in the eastern North Pacific; (2) it represents a vagrant individual from the smaller extant population found in the western North Pacific; or (3) it represents an individual from the previously thought extinct North Atlantic population. We believe that the first is the most likely, based on current population sizes, on known summer distributions, on the extent of cetacean monitoring in the North Atlantic and on the results of a performed route analysis. While it is difficult to draw conclusions from such singular events, the occurrence of this individual in the Mediterranean coincides with a shrinking of Arctic Sea ice due to climate change and suggests that climate change may allow gray whales to re-colonize the North Atlantic as ice and temperature barriers to mixing between northern North Atlantic and North Pacific biomes are reduced. Such mixing, if it were to become widespread, would have implications for many aspects of the marine conservation and ecology of these two regions.

  • Wiley, D.N., Thompson, M., Pace, R.M., and Levenson, J.  Modeling speed restrictions to mitigate lethal collisions between ships and whales in the Stellwagen Bank National Marine Sanctuary, USA.  Biological Conservation 144(9): 2377-2381, 2011.
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    Collision with ships is a significant cause of mortality among endangered whales. Collision lethality increases with vessel speed and mitigation includes slowing ships in whale dense areas. The 2181 km2 Stellwagen Bank National Marine Sanctuary (SBNMS) is a site of numerous whale/ship collisions. To understand how speed reduction measures reduce lethal collisions, we used GIS to apply hypothetical speed reductions to observed ship traffic within SBNMS. During 2006, we collected complete AIS data from SBNMS vessel traffic. We created 1.85 km2 (N = 810) grid cells covering SBNMS and determined each cell's predicted probability of lethality (PLETH) from the cell's mean speed and a mortality curve. We calculated average PLETH for the entire sanctuary (SPLETH), and used SPLETH to index status quo risk. We applied speed limits of 16, 14, 12, and 10 knots on transits and recalculated SPLETH for each scenario. Our analysis included 2,079,867 AIS points to derive 74,638 cell transits by 502 ships (>295 t). Sanctuary mean ship speed, by cell transit, was 13.5 knots (SD 4.3, range 0.1 - 42.2). The choice of speed restriction had a major impact on SPLETH: 16 knots = -3.7%, 14 knots = -11%, 12 knots = -29.4%, 10 knots = -56.7%. The conservation benefit of speed restrictions is influenced by the status quo speed of ships from which risk must be reduced. As most areas lack such data our results can provide managers with a better understanding of how speed restrictions might reduce risk in their waters.

  • Anderwald, P., Daníelsdóttir, A.K., Haug, T., Larsen, F., Lesage, V., Reid, R.J., Víkingsson, G.A., and Hoelzel, A.R.  Possible cryptic stock structure for minke whales in the North Atlantic: Implications for conservation and management.  Biological Conservation 144(10): 2479-2489, 2011.
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    The minke whale is the last of the great whale species to be hunted in significant numbers. Effective management must include an understanding of how genetic diversity is divided and distributed among putative local populations, and as for many migratory species, this is complicated for the minke whale by large-scale seasonal movement among geographic regions. The problem is that the geographic identity of breeding populations is not known, and instead these whales are predictably found and hunted where different breeding stocks may mix on seasonal feeding grounds. Here we use microsatellite DNA and mtDNA markers to investigate minke whale population structure across the species' range in the North Atlantic. We found no evidence of geographic structure comparing putative populations in recognized management areas, though some limited structure had been indicated in earlier studies. However, using individual genotypes and likelihood assignment methods, we identified two putative cryptic stocks distributed across the North Atlantic in similar proportions in different regions. Some differences in the proportional representation of these populations may explain some of the apparent differentiation between regions detected previously. The implication would be that minke whales range extensively across the North Atlantic seasonally, but segregate to some extent on at least two breeding grounds. This means that established stock boundaries in the North Atlantic, currently used for management, should be re-considered to ensure the effective conservation of genetic diversity.

  • Piroddi, C., Bearzi, G., Gonzalvo, J., and Christensen, V.  From common to rare: The case of the Mediterranean common dolphin.  Biological Conservation 144(10): 2490-2498, 2011.
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    Although overfishing has been recognized as responsible for the decline of major fish stocks, it has been less easy to demonstrate its indirect and detrimental effects on marine mammals, particularly dolphins. Competition with fisheries for the same food resources has been hypothesized to have led to the decline of several species of dolphins, including the endangered Mediterranean short-beaked common dolphin. Based on an ecosystem model for the Inner Ionian Sea Archipelago, a former hotspot for common dolphins in the Mediterranean Sea, we investigated the effect of increasing fishing effort on common dolphins, its prey and on marine biodiversity and we evaluated the outcomes of different fisheries closures (1 - closure of the purse seine fishery, 2 - closure of purse seine, trawl and beach seine fisheries, 3 - entire area closed to fisheries) ran between the years 2011 and 2030. Our results showed that local fisheries have negatively impacted the marine biodiversity of the ecosystem causing sharp declines of common dolphins and major fish stocks and weakening the robustness of the marine food web. The implementation of fisheries closures would gradually recover fish stocks, while common dolphins would increase more pronouncedly only if the study area was to be closed to all fisheries. As shown in this study, common dolphins have reflected ecosystem changes and degradation over time. Ensuring the survival of dolphin populations is thereby essential to enhance marine ecosystems and ensure sustainable fishing.

  • Jefferson, T.A. and Wang, J.Y.  Revision of the taxonomy of finless porpoises (genus Neophocaena): The existence of two species.  Journal of Marine Animals and Their Ecology 4(1): 3-16, 2011.
    Open Access >>
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    Due to extensive morphological variation and inadequately-sampled or poorly-designed studies, the taxonomy of the finless porpoises (genus Neophocaena) has been controversial for some time. An uneasy stability with the arrangement of finless porpoises into a single species consisting of three subspecies dominated for many years. However, in the past decade new data examining both morphological and molecular characters provided strong evidence for the existence of at least two distinct biological species, by demonstrating a lack of interbreeding in sympatry between the two major morphological forms of finless porpoises.  All finless porpoise specimens examined have had either a wide dorsal tubercled area or a much-narrower one, and there appears to be no overlap between the two species in this feature. Furthermore, the two species have apparently been reproductively isolated since the last glacial maximum, about 18,000 years ago. Taxonomic studies of finless porpoises are reviewed, the widely-accepted view of one species is rejected, and the two recognized species are redescribed. The revised taxonomy of the finless porpoises includes the Indo-Pacific finless porpoise (Neophocaena phocaenoides) and the narrow-ridged finless porpoise (N. asiaeorientalis), with two subspecies (Yangtze finless porpoise, N. a. asiaeorientalis, and East Asian finless porpoise, N. a. sunameri) within the latter species.

  • Bearzi, G., Reeves, R.R., Remonato, E., Pierantonio, N., and Airoldi, S.  Risso's dolphin Grampus griseus in the Mediterranean Sea.  Mammalian Biology 76(4): 385-400, 2011.
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    The ecology and status of Risso's dolphins Grampus griseus worldwide are poorly known. In the Mediterranean Sea, modern field studies of cetaceans only began in the late 1980s and this has resulted in rapid advances in knowledge of some species, but not Risso's dolphin. This paper reviews available information on the distribution and ecology of Risso's dolphins in the Mediterranean and identifies factors that may negatively affect them in this region. Risso's dolphins occur in continental slope waters throughout the Mediterranean basin and around many of the region's offshore islands and archipelagos. No synoptic estimate of abundance is available for the Mediterranean region, but densities and overall numbers are low in comparison to some other small odontocetes. Diet consists primarily of cephalopods, with a clear preference for mesopelagic squid. The principal known threat to populations in the Mediterranean is entanglement in pelagic drift gillnets. Other potential problems for Risso's dolphins in the Mediterranean include noise disturbance and ingestion of plastic debris. Conservation actions to mitigate the risk of entanglement in fishing gear are likely to benefit Risso's dolphins; specifically, the existing driftnet ban in EU waters should be strictly enforced and extended to the high seas and to waters under non-EU State jurisdiction. More and better data are needed on abundance, distribution, movements, population dynamics and trends in Risso's dolphin populations, and better information on threats (e.g. bycatch in fishing gear) is needed to inform conservation efforts.

  • Parsons, E.C.M. and Scarpaci, C.  Recent advances in whale-watching research: 2009–2010.  Tourism in Marine Environments 7(1): 43-53, 2011.
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    Whale-watching research encompasses a wide variety of disciplines and fields of study, including monitoring the biological impacts of whale-watching activities on cetaceans and assessments of the effectiveness of whale-watching management and regulations, to the sociological and economic aspects of whale watching on communities hosting such activities. This article is the latest in a series of annual digests, which describes the variety and findings of whale-watching studies published over the past year, since June 2009.

  • Laidre, K.L. and Heide-Jorgensen, M.P.  Life in the lead: extreme densities of narwhals Monodon monoceros in the offshore pack ice.  Marine Ecology Progress Series 423: 269-278, 2011.
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    There is a paucity of information on abundance, densities, and habitat selection of narwhals Monodon monoceros in the offshore pack ice of Baffin Bay, West Greenland, despite the critical importance of winter foraging regions and considerable sea ice declines in the past decades. We conducted a double-platform visual aerial survey over a narwhal wintering ground to obtain pack ice densities and develop the first fully corrected abundance estimate using point conditional mark-recapture distance sampling. Continuous video recording and digital images taken along the track-line allowed for in situ quantification of winter narwhal habitat and for the estimation of fine-scale narwhal habitat selection and habitat-specific sighting probabilities. Abundance at the surface was estimated at 3484 (coefficient of variation [CV] = 0.46) including whales missed by observers. The fully corrected abundance of narwhals was 18 044 (CV = 0.46), or approximately one-quarter of the entire Baffin Bay population. The narwhal wintering ground surveyed (~9500 km2) had 2.4 to 3.2% open water based on estimates from satellite imagery (NASA Moderate Resolution Imaging Spectroradiometer) and 1565 digital photographic images collected on the trackline. Thus, the ~18 000 narwhals had access to 233 km2 of open water, resulting in an average density of ~77 narwhals km-2 open water. Narwhal sighting probability near habitats with <10% or 10 to 50% open water was significantly higher than sighting probability in habitats with >50% open water, suggesting narwhals select optimal foraging areas in dense pack ice regardless of open water availability. This study provides the first quantitative ecological data on densities and habitat selection of narwhals in pack ice foraging regions that are rapidly being altered with climate change.

  • Raach, M., Lebeuf, M., and Pelletier, E.  PBDEs and PCBs in the liver of the St Lawrence Estuary beluga (Delphinapterus leucas): a comparison of levels and temporal trends with the blubber.  Journal of Environmental Monitoring 13(3): 649-656, 2011.
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    Due to their lipophilic properties, persistent organic pollutants (POPs) are commonly assessed using the blubber of marine mammals. However, these chemicals are also accumulating in other tissues including the liver. Some pollutants, namely perfluorinated alkyl acids, are found predominately in the liver and blood of marine mammals, and thus monitored in those tissues. This raises the question whether any tissue would represent an identical trend of POPs in the SLE beluga. The current study reports the first temporal trends of PBDEs and PCBs in the liver of 65 SLE belugas. Neither Σ7PBDEs nor major individual PBDE-homolog group concentrations showed significant trends between 1993 and 2007. Also, Σ32PCBs did not change over years, although, tetra-, penta-and hepta-PCB decreased by 7.1, 6.8 and 8.5%, respectively, in males, whereas tetra-, penta- and octa-PCBs declined by 11, 12 and 12.9%, respectively, in females. In order to compare the distribution of POPs between liver and blubber, a lipid normalised concentration ratio R(blubber/liver) for PBDEs and PCBs was calculated for each individual beluga. For all PBDE and several PCB homolog groups, mean R values were not statistically different from unity indicating that the partitioning of these POPs is governed by the tissue lipid-content. Temporal trends of R ratios of PBDEs and PCBs were also examined. There were generally no significant temporal trends except for PBDEs in males where R increased in average by 12.7 ± 2.9% yearly. The stratification of the blubber into a metabolically active (inner) and less active layers (outer blubber) may result in a slower response time of the blubber (full depth) than the liver to the recent change of contamination in the environment and explain the time trend differences between both tissues. This study suggests that the liver is more representative of recent exposure to lipophilic contaminants.

  • Seuront, L. and Cribb, N.  Fractal analysis reveals pernicious stress levels related to boat presence and type in the Indo–Pacific bottlenose dolphin, Tursiops aduncus.  Physica A: Statistical Mechanics and its Applications 390(12): 2333-2339, 2011.
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    The stress induced in the Indo-Pacific bottlenose dolphin, Tursiops aduncus, by boat presence and type was investigated in a highly urbanized coastal environment, the Port Adelaide River-Barker Inlet Estuary, South Australia. The level of stress experienced by bottlenose dolphins was inferred from the distribution patterns of their dive durations. Dive duration has previously been shown to increase under boat traffic conditions, and is considered as a typical avoidance behavior. Dive durations were opportunistically recorded from land-based stations between January 2008 and October 2010 in the absence of boat traffic, and in the presence of kayaks, inflatable motor boats, powerboats and fishing boats. Subsequent analyses were based on nearly 6000 behavioral observations. No significant differences in dive durations were found between control observations (i.e. absence of boats) and boat interferences, which could erroneously lead to conclude that boat traffic did not induce any stress in T. aduncus. In contrast, the scaling exponents of the cumulative probability distribution of dive durations obtained in the absence of boat traffic and under different conditions of boat interferences show (i) that the presence of boats affected the complexity of dive duration patterns and (ii) that stress levels were a function of boat type. Specifically, the complexity of dive duration patterns (estimated by the scaling exponent φ) did not significantly differ between control behavioral observations and behavioral observations conducted in the presence of kayaks. A significant increased in behavioral stress (i.e. decreasing values of φ) was, however, induced by the presence of fishing boats, motorized inflatable boats and powerboats. This demonstrates that traditional approaches based on the analysis of averaged behavioral metrics may not be sensitive enough to detect changes in the distribution pattern of behavioral sequences, hence underestimate the potential consequences of e.g. chronic exposure to low levels of stress. It is finally emphasized that fractal analyses of behavioral variables, and in particular the analysis of their cumulative probability distribution function, may provide a non-invasive, objective and quantitative framework that can be used to assess the changes in stress response, and subsequently evaluate the welfare status of organisms under various conditions of abiotic and/or biotic stress.

Sirenians

  • Hunter, M.E., Auil-Gomez, N.E., Tucker, K.P., Bonde, R.K., Powell, J., and McGuire, P.M.  Low genetic variation and evidence of limited dispersal in the regionally important Belize manatee.  Animal Conservation 13(6): 592-602, 2010.
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    The Antillean subspecies of the West Indian manatee Trichechus manatus is found throughout Central and South America and the Caribbean. Because of severe hunting pressure during the 17th through 19th centuries, only small populations of the once widespread aquatic mammal remain. Fortunately, protections in Belize reduced hunting in the 1930s and allowed the country's manatee population to become the largest breeding population in the Wider Caribbean. However, increasing and emerging anthropogenic threats such as coastal development, pollution, watercraft collision and net entanglement represent challenges to this ecologically important population. To inform conservation and management decisions, a comprehensive molecular investigation of the genetic diversity, relatedness and population structure of the Belize manatee population was conducted using mitochondrial and microsatellite DNA. Compared with other mammal populations, a low degree of genetic diversity was detected (HE=0.455; NA=3.4), corresponding to the small population size and long-term exploitation. Manatees from the Belize City Cayes and Southern Lagoon system were genetically different, with microsatellite and mitochondrial FST values of 0.029 and 0.078, respectively (P ≤ 0.05). This, along with the distinct habitats and threats, indicates that separate protection of these two groups would best preserve the region's diversity. The Belize population and Florida subspecies appear to be unrelated with microsatellite and mitochondrial FST values of 0.141 and 0.63, respectively (P ≤ 0.001), supporting the subspecies designations and suggesting low vagility throughout the northern Caribbean habitat. Further monitoring and protection may allow an increase in the Belize manatee genetic diversity and population size. A large and expanding Belize population could potentially assist in the recovery of other threatened or functionally extinct Central American Antillean manatee populations.

  • Nourisson, C., Morales-Vela, B., Padilla-Saldívar, J., Tucker, K.P., Clark, A., Olivera-Gómez, L.D., Bonde, R., and McGuire, P.  Evidence of two genetic clusters of manatees with low genetic diversity in Mexico and implications for their conservation.  Genetica 139(7): 833-842, 2011.
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    The Antillean manatee (Trichechus manatus manatus) occupies the tropical coastal waters of the Greater Antilles and Caribbean, extending from Mexico along Central and South America to Brazil. Historically, manatees were abundant in Mexico, but hunting during the pre-Columbian period, the Spanish colonization and throughout the history of Mexico, has resulted in the significantly reduced population occupying Mexico today.  The genetic structure, using microsatellites, shows the presence of two populations in Mexico: the Gulf of Mexico (GMx) and Chetumal Bay (ChB) on the Caribbean coast, with a zone of admixture in between. Both populations show low genetic diversity (GMx: NA = 2.69; HE = 0.41 and ChB: NA = 3.0; HE = 0.46). The lower genetic diversity found in the GMx, the largest manatee population in Mexico, is probably due to a combination of a founder effect, as this is the northern range of the sub-species of T. m. manatus, and a bottleneck event. The greater genetic diversity observed along the Caribbean coast, which also has the smallest estimated number of individuals, is possibly due to manatees that come from the GMx and Belize.  There is evidence to support limited or unidirectional gene flow between these two important areas. The analyses presented here also suggest minimal evidence of a handful of individual migrants possibly between Florida and Mexico. To address management issues we suggest considering two distinct genetic populations in Mexico, one along the Caribbean coast and one in the riverine systems connected to the GMx.

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