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November 2, 2010, Vol. 15, No. 22
Turtle banner image: Claire Fackler, NOAA National Marine Sanctuaries

In This Issue

Science in the News

Arctic Enters a “New Climate State”

The Arctic has entered a "new climate state," according to NOAA. The consequences are likely to range from greatly diminished sea ice cover in the Arctic Ocean to increasing bouts of cold winters in midlatitudes. NOAA

The Arctic has entered a “new climate state” and is unlikely to return to the conditions that have characterized it in recent centuries, according to the National Oceanic and Atmospheric Administration’s (NOAA) recently released annual Arctic Report Card. In its report, NOAA pointed out that in 2010, the duration of Arctic snow cover was the shortest since records began in 1966, while Greenland saw continued record-setting high temperatures, ice melt and glacier loss—including the calving of a 112-square-mile (290 square-kilometer) piece of Petermann Glacier in the extreme northwest of the island.

The calving and melting of freshwater glaciers, as well as sea ice melt and increased rainfall, are causing the surface waters of the Arctic Ocean to freshen. As that happens, seawater becomes more stratified, inhibiting mixing between different ocean layers and limiting the cycling of nutrients that prompt phytoplankton growth. As a result, smaller algae, which are able to survive on lesser amounts of nutrients, are beginning to thrive, at the expense of the larger algae that have traditionally dominated.

One possible consequence of this shift in algae species may be a decline in the overall productivity in Arctic waters. However, the Report Card notes some considerable variations regionally and from year to year in distribution and trends in Arctic marine life. For example, prior to 2005, as waters in the Bering Sea warmed, sea ice–dependent species such as Arctic cod appeared to be being replaced by species that prefer warmer conditions, such as pollock. However, since then the area's waters have cooled, and as a result, Arctic cod have returned south while pollock numbers have dwindled. The report’s authors point out that, on a year-to-year basis, natural cycles continue to be the most powerful drivers of change; on a longer time scale, however, the underlying trend remains one of warming.

Indeed, as the Arctic warms, it is undergoing what researchers refer to as “polar amplification,” a feedback loop in which changes lead to further warming. In particular, as Arctic sea ice declines in extent and thickness, it exposes greater amounts of open ocean to solar radiation. Whereas light sea ice reflects this radiation, the dark ocean absorbs it, making it more difficult for sea ice to re-form, leading to greater melting and so on. One possible consequence of this cycle is that rising heat from a warmer ocean may increasingly disrupt the circumpolar winds that normally confine cold air within Arctic realms, allowing blasts of cold to hurtle south. In other words, greater warmth in the higher latitudes could result in increased winter cold spells in some midlatitudes, similar to what happened when parts of the United States were buried under thick snow this past winter.

For Further Information: NOAA's Arctic Report Card may be found here: http://www.arctic.noaa.gov/reportcard/. The report's release coincided with the release of the interagency report by the White House Climate Change Adaptation Task Force, which outlines recommendations to President Obama for how Federal Agency policies and programs can better prepare the United States to respond to the impacts of climate change. Information on the Task Force and the report can be viewed at http://www.whitehouse.gov/administration/eop/ceq/initiatives/adaptation.


Researchers Find Oil on Bottom of Gulf of Mexico

Core of sediment from Gulf of Mexico The top layer of this core of sediment from the bottom of the Gulf of Mexico includes oil from the Deepwater Horizon oil spill. One researcher has said there appears to "vast amounts" of oil from the spill on the seafloor. USM-Department of Marine Science

Six months after the Deepwater Horizon accident, which claimed 11 lives and caused 185 million gallons of oil to be spilled into the Gulf of Mexico, several independent teams of researchers have found evidence that at least some of the oil has settled on the sea floor.

Scientists on the National Science Foundation research vessel Cape Hatteras found oil in sediment samples collected from a 140-mile (225-kilometer) radius around the site of the Macondo well. “Clearly, there appears to be vast volumes of oil present on the seafloor,” said Kevin Yeager of the University of Southern Mississippi. “We saw considerable evidence of it.”

That finding supports two other independent analyses. In early September, Samantha Joye of the University of Georgia led a team that found oil in the seafloor in layers that in some cases were two-inches thick. Later that month, researchers from Texas A&M University, operating from on board the Greenpeace vessel Arctic Sunrise also found oil in sediment samples.

What remains uncertain, however, is what proportion of the oil that entered the Gulf as a result of the accident has reached the seafloor and how much is diffusing in the water column. Speaking at the U.S. Oil Spill Commission hearings in late September, oceanographer Ian McDonald of Florida State University estimated that more than half the oil from the spill remained in the Gulf, and that “much of it is now buried in marine and coastal sediments.”

For Further Information: Background on the Cape Hatteras survey is available at http://www.sailblogs.com/member/chmaster/?xjMsgID=146613; on the Arctic Sunrise voyage at http://www.greenpeace.org/usa/en/news-and-blogs/news/oilspilltruth/; and on the work of Samantha Joye of the University of Georgia at http://gulfblog.uga.edu/.

Science Briefs

High Levels of Carbon Dioxide Could Kill Antarctic Krill

Antarctic krill
Researchers in Australia have found that under laboratory conditions acidified seawater, which is caused by adding carbon dioxide, kills embryos of Antarctic krill. They say more study is needed, however, to determine what levels of future ocean acidification are likely to harm krill populations in the Southern Ocean. Uwe Kils

Increased levels of carbon dioxide in seawater kill krill embryos, but only if those levels are significantly higher than at present, researchers have found. Writing in the journal Biology Letters, So Kawaguchi of the Australian Antarctic Division and colleagues note that one consequence of increased fossil fuel emissions is higher concentrations of carbon dioxide reaching ocean waters. A principal effect of this is decreasing the pH levels of seawater, a process known as ocean acidification.

In an attempt to test the possible consequences of such ocean acidification on the development of krill, the keystone species of the Antarctic marine ecosystem, Kawaguchi and colleagues set up three seawater tanks bubbled with carbon dioxide at the current level of 380 parts per million (ppm) as well as medium (1,000 ppm) and high (2,000 ppm) levels. In each of those tanks, the researchers attempted to grow krill embryos. There was no change in the development of the embryos in the tanks with current and medium levels of carbon dioxide, but in the tanks containing high levels, none of the embryos survived to hatch.

Under few scenarios are carbon dioxide concentrations in Antarctic waters anticipated to reach 2,000 ppm; however, at current rates of emission increases, researchers predict that by 2100, they will reach 1,400 ppm in the depths of the Southern Ocean. Kawaguchi and colleagues write that their study is the beginning of research into the effects of ocean acidification on krill and that further studies will be necessary to identify the exact carbon dioxide concentration “tipping point” as well as the potential impact of ocean acidification on the later stages of the species’ life cycle.

Source: Kawaguchi, S., et al. 2010. Will krill fare well under Southern Ocean acidification? Biology Letters doi:10.1098/rsbl.2010.0777

Contact: So Kawaguchi, Australian Antarctic Division. E-mail: so.kawaguchi@aad.gov.au.


Myanmar Hunger Imperils Critically Endangered Sandpiper

Spoon-billed sandpiperThe critically endangered spoon-billed sandpiper may become extinct within 10 to 20 years, in part from hunters in the impoverished nation in Myanmar catching them in nets. Chaiwat Chinuparawat/www.the worldsrarest.com

The spoon-billed sandpiper, a shorebird or wader that breeds in northeastern Russia and winters in southeast Asia, is in danger of extinction within 10 to 20 years, according to researchers.

Writing in the Wader Study Group Bulletin, Christoph Zöckler and colleagues note that the spoon-billed sandpiper was probably never common; however, in the mid-1970s, its population was estimated at about 6,000. By 2000, the species was thought to be possibly in decline, and surveys in 2004 revealed the population had dropped below 1,000. More recent surveys suggested a continued rapid decline, and by 2009 researchers estimated the population had 120 to 220 breeding pairs.

As recently as 2005, very little was known about the sandpiper's wintering areas, prompting the establishment of further field surveys. These determined that the species had wintered from India and Sri Lanka in the west to Vietnam in the east, but had now disappeared from those areas. A major cause of the decline has been the loss of the species' tidal flat habitat, but the sandpiper's continued decline suggested ongoing pressures in an as-yet unidentified wintering area. Beginning in 2008, researchers were able to visit Myanmar, which had been nominated as a likely candidate on the basis of its proximity to other known wintering areas, and also because three skins had been returned from there in the 1800s.

Here, the researchers found one area that they estimated contained about half of the estimated remaining global population of spoon-billed sandpipers. But these remaining birds faced an additional problem: Due to chronic poverty and hunger, exacerbated by declines in local fisheries, local villagers deployed thin monofilament nets to catch birds for food, and although they did not specifically target spoon-billed sandpipers, they apparently caught the species with some frequency. With no more than approximately 200 birds in the population, such catches are highly unlikely to be sustainable. The authors suggest that without a conservation program that includes, among other elements, financial inducement not to catch spoon-billed sandpipers, the species is likely to become extinct within 10 to 20 years.

Source: Zöckler, C., et al. 2010. Hunting in Myanmar is probably the main cause of the decline of the Spoon-billed Sandpiper Calidris pygmeus. Wader Study Group Bulletin 117 (1): 1-8.

Contact: Christoph Zöckler, ArcCona Consulting. E-mail: cz@arccona.com.


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Banner image credit: Claire Fackler, NOAA National Marine Sanctuaries