'Dramatic' loss of harp seals amid warming: study

WASHINGTON — Harp seal pups off the coast of eastern Canada are dying at alarming rates due to a loss of winter ice cover, according to US scientists who questioned on Wednesday if the population will be able to recover.

The study by researchers at Duke University shows that seasonal ice cover in the harp seal breeding regions of the North Atlantic Ocean has declined about six percent per decade since 1979, when satellite data began.

The result has been entire generations of newly born seal pups dying due to their disappearing habitat, said the study published in the open access science journal PLoS ONE.

"The kind of mortality we're seeing in eastern Canada is dramatic," said co-author David Johnston, a research scientist at the Duke University Marine Lab.

"Entire year-classes may be disappearing from the population in low ice years -- essentially all of the pups die," he said. "It calls into question the resilience of the population."

For recent data, researchers looked at satellite images of winter ice from 1992 to 2010 in the Gulf of St. Lawrence, a prime breeding region off the east coast of Canada, and compared them to yearly reports of dead seal pup strandings in the region.

They also compared stranding rates to records of a climate phenomenon known as the North Atlantic Oscillation, which controls the intensity and track of westerly winds and storms and exerts a major influence on sea ice formation.

They found that years of weaker NAO and lighter ice cover showed higher death rates among seal pups.

While harp seals have adapted to the earlier spring melts in recent years by developing shorter 12-day nursing periods, it remains unclear if their population can sustain itself against sea ices losses over time.

"As a species, they're well suited to deal with natural short-term shifts in climate, but our research suggests they may not be well adapted to absorb the effects of short-term variability combined with longer-term climate change and other human influences such as hunting and by-catch," Johnston said.

The team also looked back at data from 1950 to 1972 which showed that NAO weather changes were tied to big declines in the seal population, followed by period of recovery from 1973 to 2000.

"But there's a caveat: regardless of NAO conditions, our models show that sea ice cover in all harp seal breeding regions in the North Atlantic have been declining by as much as six percent a decade over the study period," added Johnston.

"The losses in bad years outweigh the gains in good years."

http://www.google.com/hostednews/afp/article/ALeqM5hsCyhCVoTEZAyNZE73rWRGFpSGNw

Will Antarctic Worms Warm to Changing Climate?

ScienceDaily (Dec. 20, 2011) — Researchers at the University of Delaware are examining tiny worms that inhabit the frigid sea off Antarctica to learn not only how these organisms adapt to the severe cold, but how they will survive as ocean temperatures increase.

The National Science Foundation study, led by Adam Marsh, associate professor of marine biosciences in UD's College of Earth, Ocean, and Environment, also will compare the process of temperature adaptation in the polar worm, known scientifically as Capitella perarmata, with that of a close relative that inhabits temperate waters, Capitella teleta.

"By comparing these two marine species, we hope to assess how a polar environment shapes responses to environmental stress," says Marsh. "By better understanding how the environment can trigger genetic changes -- through the genes the polar worm turns on or 'expresses' -- we can gain insight into the potential impact of global warming on marine ecosystems."

Arriving in late August at McMurdo Station on Ross Island, Antarctica's largest outpost, Marsh and his research team undertook a series of dives in the freezing waters over the next two months to collect the polar sea worms, which are segmented like earthworms but belong to the class known as "polychaetes."

At a mere half-inch long and no thicker than the lead in a No. 2 pencil, Capitella perarmata would be a challenge to collect even on dry land. Because the worms feed on organic matter, the researchers have found the most abundant concentrations in the top layer of sediment from McMurdo Station's old sewage outfall. The divers collect buckets filled with sediment, from which the worms are sieved


Read more here ...

Owl Eggs Reveal Complex Pollutant Patterns

An animal's load of persistent organic pollutants depends on more than the amount of the chemicals in the environment, according to a long-term study of tawny owls. The study connects variations of pollutant levels in the owls' eggs with changes in climate conditions and the birds' food supply (Environ. Sci. Technol., DOI: 10.1021/es201786x).

Every year since 1986, Georg Bangjord, a study co-author and bird enthusiast who lives in Trondheim, Norway, has collected egg samples from more than 100 tawny owl nest boxes. Jan Bustnes of the Norwegian Institute of Nature Research and his colleagues have been studying the concentrations of pollutants in these eggs. The owls accumulate chemicals, including polychlorinated biphenyls (PCBs), DDT, and polybrominated diphenyl ethers (PBDEs) from their prey, and store them in their fat. When the females lay their eggs each year, they transfer some of those chemicals to the eggs. In 2007, Bustnes and his colleagues reported that concentrations of these chemicals in the eggs had declined since the 1980s (Environ. Sci. Technol., DOI: 10.1021/es071581w).

Despite the overall decline, the researchers also noticed significant year-to-year variations in the pollutant levels. Bustnes and his colleagues decided to examine how variables such as climate conditions or food availability might have affected the chemicals' levels. So they combined their pollutant data with yearly observations of prey numbers and snow depth, along with climate data from the North Atlantic Oscillation index. They then ran statistical analyses to look for trends.

Owl eggs had greater levels of PCBs and DDT during winters with lower temperatures, periods of high snowfall, and seasons with smaller populations of their preferred prey, voles. Colder temperatures and scarce food sources could prompt owls to burn more of their fat stores, which contain high levels of the pollutants. As the owls metabolize the fat, greater amounts of the pollutants enter their blood stream and eventually accumulate in their eggs, Bustnes says. Under these conditions, the owls also lay fewer eggs, which could further concentrate the chemicals, he says.
The trend for PBDEs, the chemicals found in flame retardants, was slightly different. Levels of those chemicals also increased in eggs during colder, snowier winters, but only when voles were plentiful. Bustnes says there isn't a clear explanation for the PBDE trend.

Integrating food supply data with physical data, such as the North Atlantic Oscillation index, is a new and interesting way to understand variations in pollutant loads, says Craig Hebert, a research scientist at Environment Canada, the nation's environmental agency. The study "emphasizes how complex the interpretation of some of these temporal trends can be," and why researchers should consider multiple variables when analyzing pollutant levels in animals, he says.

Karen Foster, a postdoctoral researcher at Trent University, in Canada, adds that the data suggest that simply reporting the concentrations of pollutants measured in wildlife is not sufficient: "We really need to understand why we're seeing these concentrations."
http://pubs.acs.org/cen/news/89/i36/8936scene.html