Monday, March 22, 2010

Iron seeding oceans poses toxic risk

Margaret Munro in Canwest News Service (Canada): Sprinkling iron in the sea has long been touted as a fix for global warming, but researchers are now warning such geoengineering could nourish toxic algae. Tests conducted by a Canadian-U.S. team show that enriching water with iron favours the growth of Pseudo-nitzschia, an algae that pumps out a potent neurotoxin. It can be lethal to seabirds and marine mammals, and is linked with amnesic shellfish poisoning in humans, which can be deadly.

The findings "raise serious concerns" about large-scale iron fertilization, the team reports in the current issue of the journal Proceeding of the National Academy of Sciences. "It is an indication that we are not the masters of nature when it comes to large-scale ecological manipulations," said Charles Trick, an ecosystem researcher at the University of Western Ontario and lead author of the study.

Trick and his colleagues ran a series of experiments in tanks on the deck of a research ship near Station Papa in the Gulf of Alaska. They found that the toxin-producing Pseudo-nitzschia thrived in sea water enriched with iron. The algae accounted for just a small fraction of algae and plankton in the water at the beginning of the experiments, but eventually dominated the populations in the tanks.

The iron-rich environment also appeared to increase the amount of neurotoxin, domoic acid, produced by individual organisms, the scientists say. For other organisms, domoic acid is a potent toxin. … "It could be a show stopper," Trick said, when asked if the toxic algae could kill large-scale ocean fertilization….

Kelp on the beach at Nissen Bight, Cape Scott Provincial Park, shot by Clayoquot, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

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