For the latest ocean news,
subscribe to Ocean Update
and our other free newsletters.

Need a source or more
information? Contact us at
media@seaweb.org or
301.495.9570.

In This Issue

• Ocean Chemistry Changing at 'Unprecedented Rate'
• Polar Bears Photographed Climbing Cliffs to Eat Seabirds
• Whale Feces Could Boost Southern Ocean Ecosystem

Science in the News

Ocean Chemistry Changing at 'Unprecedented Rate'

Ocean acidification caused by the massive increase in carbon dioxide emissions reduces the ability of corals (such as this Acropora table coral on the Great Barrier Reef) to form their skeletons. Pete Faulkner, Mission: awareness/Pew Environment Group

The chemistry of the ocean is changing at an unprecedented rate, according to a recent report from the National Research Council (NRC) of the National Academy of Sciences.

The report, Ocean Acidification: A National Strategy to Meet the Challenges of a Changing Ocean, underlines growing concerns over the effect on the ocean of increasing emissions of carbon dioxide. The ocean absorbs approximately one-third of the carbon dioxide emitted by human activities, moderating the impacts of climate change but causing seawater to become more acidic. The average pH of ocean surface waters has dropped from approximately 8.2 to 8.1 since the beginning of the Industrial Revolution and is predicted to drop by a further 0.2 or 0.3 units by the end of the 21st century, under current emissions scenarios. The NRC report states that "the rate of this change exceeds any known change in ocean chemistry for at least 800,000 years."

This speed of change is significant. Many millions of years ago, atmospheric carbon dioxide concentrations were significantly higher than those of the present. However, increases in atmospheric, and hence oceanic, carbon dioxide levels unfolded over millennia, allowing natural chemical processes to compensate and maintain a steady pH. The present rate at which acidification is taking place seems likely to overwhelm the counterbalancing effects of those natural processes.

The NRC report notes that research into the impacts of ocean acidification is still in its infancy. Although a great deal of research has been conducted during the last several years, most studies on the biological effects of ocean acidification have dealt with acute responses in a few species (primarily shell-building mollusks and corals). However, very little is known about the impacts of acidification on many ecologically or economically important organisms, their populations and communities; the effects on a variety of physiological and biogeochemical processes; and the capacity of organisms to adapt to projected changes in ocean chemistry.

To research these impacts, the NRC recommends the initiation of a federally funded National Ocean Acidification Program that would include: an integrated ocean acidification observation network; research in eight broad areas to fulfill critical information gaps; assessments to identify stakeholder concerns and a process to provide relevant information for decision support; a data management office that would ensure data quality, access and archiving, plus an information exchange that would provide research results, syntheses and assessments to managers, policymakers and the general public; facilities to support high-quality research and training of ocean acidification researchers; and a 10-year strategic plan for the program that will identify key goals, set priorities and allow for community input, in addition to a detailed implementation plan.

For Further Information: A press release and contact information is available at www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=12904. A summary of the report can be downloaded from www.nap.edu/catalog.php?record_id=12904

Report coauthor James Berry was among the expert witnesses testifying on the impacts of ocean acidification before the U. S. Senate Committee on Commerce, Science and Transportation on April 22. Details of that hearing, including an archived webcast, are available online at the Senate website.

Science Briefs

Polar Bears Photographed Climbing Cliffs to Eat Seabirds

Researchers believe changing ice conditions may make this rarely observed behavior of a polar bear climbing a cliff to eat murre eggs and chicks more frequent. Kerry Woo

Scientists have documented polar bears preying on seabird eggs and chicks in Arctic Canada and believe this behavior may be a consequence of climate change.

Polar bears spend most of the year prowling sea ice in search of ringed seals and other marine mammal prey. However, in parts of their range, the melting of sea ice in summer forces them ashore until the ice freezes again in the fall. On land, polar bears have been seen eating grasses, algae, carrion and, on occasion, live prey ranging from rodents to caribou. But such terrestrial feeding has been widely considered opportunistic. In a new paper in the journal Polar Biology, however, Paul Smith of Environment Canada and colleagues report two instances of polar bears walking through snow goose colonies in Canada's northern Hudson Bay, methodically eating the eggs in every nest, and two occasions on which a solitary bear climbed cliff ledges to eat eggs and chicks of thick-billed murres. In every instance, the predation on the bird colonies was catastrophic: on three of the four occasions, the bears ate every egg, and each time a bear preyed on the murre colony, it ate all the chicks.

Smith and colleagues note that such predation may be becoming more frequent. In addition to their own observations in Canada, they report that bears have become more numerous during the bird-breeding season in west Spitsbergen, where they have been observed consuming the eggs of barnacle geese, thick-billed murres and little auks. Additionally, although polar bears have been recorded in a snow goose colony near Churchill, Manitoba, just six times in the past 40 years, four of those occasions have taken place since 2000.

The authors hypothesize that the apparently increased frequency of such encounters may be attributable to climate change. Climatic warming has resulted in progressively earlier sea ice breakup in Hudson Bay, and as a result, on Coats Island—the site of the two murre predation incidents and one of the two snow geese colonies—the first polar bears are now coming ashore almost three weeks earlier than they did in 1985. As a result, the birds' nesting seasons and the time when the bears are on land now overlap.

Smith and colleagues conclude that their observations "demonstrate an earlier arrival of bears to land in this region, suggest an increase in their consumption of eggs and highlight the complexity of ecological interactions that may occur in a changing arctic environment."

Source: Smith, P.A., et al. 2010. Has early ice clearance increased predation on breeding birds by polar bears? Polar Biology DOI 10.1007/s00300-010-0791-2

Contact: Paul A. Smith, Environment Canada. E-mail: paulallen.smith@ec.gc.ca

Whale Feces Could Boost Southern Ocean Ecosystem

The feces from this endangered blue whale and other baleen whales contain high concentrations of iron, an element that is vital to the productivity of marine ecosystems. NOAA

Researchers have found that the feces of baleen whales in the Southern Ocean are rich in iron and, as iron promotes phytoplankton growth, are a vital component of the Antarctic ecosystem.

In a new study in the journal Fish and Fisheries, Stephen Nicol of the Australian Antarctic Division and colleagues found that whale feces contain approximately 10 million times as much iron as Antarctic seawater. By sampling genetic material in 27 fecal samples from four whale species, the scientists established that the bulk of the iron came from krill. This allowed them to construct a picture of a Southern Ocean food web in which whale feces play a key role. The feces stimulate the growth of phytoplankton, which are eaten by krill. The krill concentrate the iron in their tissue, and they are in turn eaten by whales.

Nicol and colleagues estimate that, prior to commercial whaling, baleen whales consumed about 190 million metric tons of krill every year and produced 7,600 metric tons of iron-rich feces, accounting for approximately 12 percent of the iron at the surface of the Southern Ocean. The researchers point out that, in addition to supporting the marine food web, phytoplankton absorb carbon dioxide, and therefore that if whale populations recovered, and phytoplankton growth increased accordingly, this could help mitigate the effects of climate change.

They conclude that their findings provide further arguments for protecting already-depleted whale populations from further exploitation and supporting efforts to stimulate their recovery.

Source: Nicol, S., et al. 2010. Southern Ocean iron fertilization by baleen whales and Antarctic krill. Fish and Fisheries DOI 10.1111/j.1467-2979.2010.00356.x

Contact: Stephen Nicol, Australian Antarctic Division. E-mail: steve.nicol@aad.gov.au

Read past issues of Ocean Update in the archive >>