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January 12, 2010, Vol. 15, No. 1
In This Issue
Science in the NewsCensus to Reveal Number of Marine Species During 2010, Year of BiodiversityA worldwide team of scientists has discovered more than 5,000 ocean species during 10 years of surveys designed to assess the diversity, distribution and abundance of marine life. The Census of Marine Life, a network of researchers in more than 80 nations, will release its final report in October, the first attempt at compiling a comprehensive global list of all forms of life in the sea.
The project's scientists estimate that the final total of marine species will be approximately 235,000, of which 5,600 so far have been identified and described for the first time as a result of Census expeditions. Census researchers plan also to provide an estimate of the number of species that remain to be discovered, potentially up to a million if all small animals and microscopic organisms known as protists are included. The Census network's research has been conducted through an unprecedented program of international collaboration that has included 14 field projects, three focused on globally distributed species—top predators such as tuna, zooplankton and microbial life—and 11 on different habitats such as seamounts or the Arctic Ocean. Five of those projects have involved habitats in the deep sea—ocean realms deeper than sunlight can penetrate. So far, Census scientists have catalogued 17,650 species at depths greater than 200 meters (0.12 miles), the point at which sunlight in insufficient for photosynthesis, with 5,722 of them found deeper than 1,000 meters (0.6 miles) and some even as deep as 5,000 meters (3 miles). Many of the species in these cold, dark realms feed on the detritus that falls to the ocean floor from the sunlit zones, while others feast on the carcasses and skeletons of dead whales and others consume bacteria that can break down oil, sulfur and methane. Half a mile below the surface in the Gulf of Mexico, a robotic arm on a Remotely Operated Underwater Vehicle (ROV) plucked a solitary tubeworm from a hole in the sea floor, prompting crude oil to stream from hole and animal alike; the tubeworm was dining on chemicals from decomposing oil. Other discoveries Census scientists made in the ocean depths included an "indescribable" catch of multi-hued invertebrates more than half a mile beneath the surface waters along the Mid-Atlantic Ridge, the Antarctic's first recorded whalebone-eating worm and on one cruise that examined the seafloor of the southeastern Atlantic, a clutch of 680 copepods, of which only seven were known to have been seen before.
The Census of Marine Life's findings come as the United Nations has declared 2010 the Year of Biodiversity, a move intended to "raise awareness of the importance of conserving biodiversity for human well-being," and "enhance public knowledge of the threats to biodiversity and means to conserve it." A key benefit of biodiversity the United Nations is promoting is that it could aid in the provision of ecosystem services. The Year of Biodiversity website points out, for example, that whereas establishing a network of marine protected areas globally could cost between $5 billion and $19 billion, it could help safeguard $70 billion to $80 billion worth of fish catches, as well as marine ecosystem services valued at $4.5 to $6.7 trillion annually. For Further Information: Full details about the Census of Marine Life, including press releases and descriptions of the 14 field projects, is available at www.coml.org. Information about the Year of Biodiversity is available via the website of the Convention on Biological Diversity: www.cbd.int/2010. Science BriefsCoconut-Carrying Octopus May Be First Invertebrate to Use Tools
Scientists have discovered octopuses in Indonesian waters collecting coconut shells for shelter, behavior that the researchers say is the first evidence of an invertebrate using tools. In a recent edition of the journal Current Biology, Julian Finn of Museum Victoria in Australia and colleagues write that, during dives off the coasts of northern Sulawesi and Bali, they documented four cases of veined octopuses picking up stacked, hollowed-out halves of coconut shells and carrying them under their bodies as much as 65 feet (20 meters) along the seabed before climbing inside and closing the two halves together to create a shelter. Finn and colleagues write that the fact that the octopuses carry the coconuts for future use—as opposed to hermit crabs, for example, that immediately occupy empty shells—makes the behavior unique among observed invertebrate behavior. "The discovery of this octopus tiptoeing across the sea floor with its prized coconut shells suggests that even marine invertebrates engage in behaviors that we once thought the preserve of humans," they conclude. Source: Finn, J.K, et al. 2009. Defensive tool use in a coconut-carrying octopus. Current Biology 19(23): R1069-R1070. Contact: Julian K. Finn, Museum Victoria, Australia. E-mail: jfinn@museum.vic.gov.au Blue Whales Are Singing More DeeplyThe songs of blue whales are becoming progressively deeper in tone, but why remains a mystery. Independent researcher Mark McDonald began setting up acoustic detectors to study blue whales in the Pacific Ocean in 2001. He then noticed that he had to shift the detector lower in frequency each year.
This prompted McDonald and colleagues to compare blue whale vocalizations as far back as 1959. In a recent issue of Endangered Species Research, McDonald and colleagues reported that tonal frequencies have shifted downward in blue whale songs around the world since this time, although to different degrees in different areas. In the most extreme example, in the eastern North Pacific, songs are now sung at a frequency 31 percent lower than in 1965. McDonald and colleagues tentatively suggest the change may be a consequence of blue whale populations beginning to rebound after several decades of protection from commercial whaling. Greater numbers of whales may mean reduced distance between individual whales, enabling them to shift to lower tones that do not travel as far underwater; at the same time, increasing populations means more males singing to attract mates, and McDonald and colleagues speculate that deeper songs may be more attractive to females. Source: McDonald, M.A., et al. 2009. Worldwide decline in tonal frequencies of blue whale songs. Endangered Species Research 9: 13-21 Contact: Mark A. McDonald, Whale Acoustics, Bellvue, Colorado. E-mail: mark@whaleacoustics.com Nonlethal Levels of Pesticide Can Impair Salmon PopulationsBiologists have found that even short-term exposure to nonlethal levels of pesticides can be sufficient to limit the growth and size of wild salmon populations. Writing in the journal Ecological Applications, David Baldwin of the National Oceanic and Atmospheric Administration (NOAA) and colleagues studied the impact of pesticides on individual salmon using existing data, and then devised a model to calculate the productivity and growth rate of the population.
The biologists noted that previous studies had found that pesticides directly affected the activity of an important enzyme in salmons' brains, causing them to eat less. The researchers then took this information and used their model to calculate its effect on the growth and size of individual salmon and the survival rate during and following ocean migration. In one scenario, the model predicted that, over the course of 20 years, the number of spawning salmon in a recovering population returning from the ocean could increase by 68 percent, whereas in a population that was not exposed to pesticides the increase could be as high as 523 percent. The model showed that just four days of exposure to sublethal levels of pesticides were sufficient to reduce growth and survival rates of individual salmon. Source: Baldwin, D.H., et al. 2009. A fish of many scales: Extrapolating sublethal pesticide exposures to the productivity of wild salmon populations. Ecological Applications 19(8): 2004-2015 Contact: David Baldwin, National Oceanic and Atmospheric Administration. E-mail: David.Baldwin@noaa.gov. |
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