Toxins from harmful algae found in marine mammals

ANCHORAGE, Alaska — A review of more than 900 marine mammals hunted, stranded or captured for research along Alaska’s coast has found toxins from harmful algae in 13 species, creating concern that the natural poisonous substances could increase as water temperatures warm and sea ice diminishes.

Algal toxins were present in animals sampled from southeast Alaska to the Arctic Ocean, according to researchers from the National Oceanic and Atmospheric Administration and other agencies.

Algal toxin has led to deaths of sea lions documented since 1998 in Central California. They have been found previ- ously in Alaska, at times creating health concerns for people eating clams, but have not been documented to this extent, said Kathi Lefebvre, a research biologist for the National Oceanic and Atmospheric Administration.

“The real concern is that the waters are warming and the sea ice is melting and the light is more available, making it more favorable for these blooms of algae,” she said.

Harmful algae species produce toxins. When conditions are right, with optimal temperature and nutrients, harmful algae can grow rapidly divide and create dense blooms. They’re eaten by zooplankton or filter feeders such as clams, shellfish or tiny fin fish, allowing the toxin to move higher in the food web.

Lefebvre is program leader for NOAA’s West Coast Wildlife Algaltoxin Research and Response Network in Seattle, which looked at samples from 905 animals collected in Alaska wildlife over nine years.

Researchers looked for domoic acid and saxitoxin.

Domoic acid has killed California sea lions. A study last year indicated affected animals that survive can suffer brain damage that leads to significant deficits in spatial memory, which could affect their ability to forage, migrate or avoid ship strikes, Lefebvre said. Domoic acid was found in all 13 Alaska species reviewed.

Saxitoxin, which causes paralytic seafood poisoning in clams, was found in 10 of the 13 species.