April 19, 2011

Endangered Pacific Seabird Feathers Prove Pollution Rise

Feathers collected from the rare Pacific black-footed albatross over the past 120 years have helped researchers from Harvard University track increases in the neurotoxin methylmercury in the endangered bird, which forages extensively throughout the Pacific, reports AFP.

Scientists took the feather samples from two US museum collections -- the Harvard University Museum of Comparative Zoology and the University of Washington Burke Museum of Natural History and Culture. Studies of the feathers showed that the increase in methylmercury levels can be observed and tracked over broad time periods in organisms that live in the Pacific Ocean.

Methylmercury can cause central nervous system damage and comes from burning fossil fuels. Rising levels of mercury in fish and seafood could pose dangers to human health, and pregnant women and young children are particularly urged to limit the amount of some types of fish in their diets.

The study, published early in the online edition of the Proceedings of the National Academy of Sciences, has important implications for both environmental and public health, say authors of the study.

"The Pacific in particular warrants high conservation concern as more threatened seabird species inhabit this region than any other ocean," said lead author Anh-Thu Vo, who did her research while an undergraduate at Harvard and is currently a graduate student at the University of California, Berkeley.

"Given both the high levels of methylmercury that we measured in our most recent samples and regional levels of emissions, mercury bioaccumulation and toxicity may undermine reproductive effort in this species and other long-lived, endangered seabirds," she said.

"Using these historic bird feathers, in a way, represents the memory of the ocean," said study co-author Michael Bank, a research associate in the Department of Environmental Health at Harvard School of Public Health.

"Our findings serve as a window to the historic and current conditions of the Pacific, a critical fishery for human populations," said Bank.

The highest concentrations in feathers were linked to exposure by the birds after 1990, which coincides with a recent spike in pollution from Asian carbon emissions in the Pacific region, the study said.

Asian mercury pollution jumped from 700 tons annually in 1990 to nearly 1,300 tons in 2005, according to the study, noting that China became the largest emitter of mercury pollutants in 2005, with 635 tons.

Researchers found the lowest levels of mercury in bird feathers from before 1940.

Mercury-laden feathers from the black-footed albatross suggest a strong link between the toxin and the birds' diet, which consists primarily of fish, fish eggs, squid, and crustaceans in the Pacific.

The high levels of mercury in the feathers could also indicate the increasing decline in the birds' population. The population of the endangered animal is estimated to be around 129,000 individuals in the Pacific, mainly near Hawaii and Japan.

Banks said that "Methylmercury has no benefit to animal life and we are starting to find high levels in endangered and sensitive species across marine, freshwater, and terrestrial ecosystems, indicating that mercury pollution and its subsequent chemical reactions in the environment may be important factors in species population declines."

Consumption of mercury-tainted fish from the Pacific Ocean is an important source of human exposure to methylmercury in the United States and may lead to adverse neurodevelopment effects in children, Bank added.

"Much of the mercury pollution issue is really about how much society values wild animal populations, yet we are also faced with the tremendous public health challenge of communicating potential risks from mercury exposure to vulnerable adult and child human populations. Although most people have low or no risk from mercury exposure, for the people who are at risk, for example, from excessive fish consumption, the problem can be considerable," he said.


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