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Seafloor critters under ice.
Photo Credit: Steve Clabuesch/Antarctic Photo Library
An underwater scene in McMurdo Sound, which is covered by sea ice. A census of marine plant and animal life has tallied more than 8,200 species in the Antarctic. The final report is due out next month.

Roll call

Marine census inventories species diversity in key ecosystems including Antarctic

What lives in the ocean?

That’s the central question of an international project to inventory species diversity and distribution in key marine ecosystems around the world. Scientists involved in the Census of Marine Life External Non-U.S. government site announced preliminary results of the decade-long survey this month ahead of the final summary scheduled in October.

The data from the census includes information from 25 regions around the world including the Antarctic. The results were reported through a series of articles in the open access journal PLoS ONE, which is published by the Public Library of Science. [See related press release External Non-U.S. government site.]

The waters around Australia and Japan were the most diverse, each region featuring nearly 33,000 forms of life. The seas off China, the Mediterranean Sea and the Gulf of Mexico rounded out the top five most diverse areas for known species.

Antarctica ranked 15th with 8,200 identified plant and animal species. Crustaceans (including crabs, lobsters, crayfish, shrimp, krill and barnacles) accounted for about 35 percent of the Antarctic species, by far the largest group. On the other hand, fish comprised only 4 percent of the Antarctic species.

Endemic species comprise about half of New Zealand and Antarctic marine species and a quarter of those in Australian and South African waters. The proportion of species not yet described is estimated at 39 to 58 percent in Antarctica.

The data for the census come from the combined efforts of the Census of Antarctic Marine Life (CAML) External Non-U.S. government site and the Scientific Committee on Antarctic Research Marine Biodiversity Information Network (SCARMarBIN) External Non-U.S. government site to form the Register of Antarctic Marine Species External Non-U.S. government site.

CAML is one of 17 projects under the Census of Marine Life. The National Science Foundation External U.S. government site, which manages the U.S. Antarctic Program External U.S. government site, is a sponsor of the Census of Marine Life.

“Most species in the Southern Ocean are rare, with over half of the known benthic [seafloor-dwelling] species having only been found once or twice,” wrote Huw J. Griffiths External Non-U.S. government site, with the British Antarctic Survey External Non-U.S. government site and author of the PLoS ONE article on the Antarctic titled, “Antarctic Marine Biodiversity — What Do We Know About the Distribution of Life in the Southern Ocean?”

“This inventory was urgently needed for two reasons,” said Mark Costello External Non-U.S. government site of the University of Auckland External Non-U.S. government site, New Zealand, and lead author of the collection summary in a press statement. “First, dwindling expertise in taxonomy impairs society’s ability to discover and describe new species. And secondly, marine species have suffered major declines ... due to human activities.”

Photo Credit: Kyle Hoppe/Antarctic Photo Library
Krill, a type of crustacean, which account for about 35 percent of Antarctic species.
Photo Credit: Henry Kaiser/Antarctic Photo Library
A jellyfish in McMurdo Sound.

Griffiths’ paper said that the huge area covered by the Antarctic and the previous lack of good baseline knowledge have made it difficult to assess the true human impact on the region.

“Our knowledge of the biodiversity of the Southern Ocean is largely determined by the relative inaccessibility of the region,” he wrote. “Benthic sampling is largely restricted to the shelf; little is known about the fauna of the deep sea. The location of scientific bases heavily influences the distribution pattern of sample and observation data, and the logistical supply routes are the focus of much of the at-sea and pelagic work.”

At least four species of cetacean (such as whales) and 18 species of birds found in the Southern Ocean are currently classified as threatened or endangered on the International Union for the Conservation of Nature Red List External Non-U.S. government site, according to the paper.

“There have been no recorded extinctions in the Antarctic since research began, but considering that many species are known from a single specimen or scientific cruise, our ability to comment is greatly restricted,” Griffiths wrote.

The main threats to marine life worldwide have been overfishing, lost habitat, invasive species and pollution, according to the PLoS One studies. Emerging threats include rising water temperature and acidification of sea water.

“Overexploitation of living resources [in Antarctica], such as krill, fish, and their associated bycatch, is a major threat to the pelagic ecosystem,” Griffiths wrote. “Benthic trawling in the South Georgia region was banned because of overfishing in the 1980s, but longline fishing still continues.

“Although commercial fishing in Antarctica is heavily legislated, one of the biggest problems faced by fishery managers … is illegal, unlicensed vessels,” the paper also reported.

There are currently no records of successfully established invasive marine animal species within the Southern Ocean, according to the paper. However, at least one recent science expedition along the Antarctic Peninsula reported seeing a massive influx of king crabs at relatively shallow depths along the continental shelf. [See related article: Changing course.]

A separate research cruise funded by the NSF’s Office of Polar Programs External U.S. government site is planned for the upcoming field season to assess the status of crab populations in western Antarctica and their potential to disrupt benthic communities. [NSF-funded research: James McClintock, University of Alabama at Birmingham External Non-U.S. government site, Award No. 0838844 External U.S. government site]

The effort to count polar species ramped up during the International Polar Year (IPY) External U.S. government site, a two-year science campaign in the Arctic and Antarctic. CAML-related expeditions during IPY involved an estimated 34 nationalities, 18 vessels and 321 scientists between 2007 and 2009.

Almost all the species in the key regional areas like Antarctica are included in a list of 185,000 marine species created by the World Register of Marine Species (WoRMS) External Non-U.S. government site, an affiliate of the Census of Marine Life. In October, the Census will release its latest estimate of all marine species known to science. The list is predicted to exceed 230,000.

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