The Alaskan food web contains toxins from harmful algae. Testings reveal that the toxins are present in concentrations that are high enough to be detected in marine mammals such as whales, seals, porpoises, walruses and sea otters.

Harmful Algae, Spotted

Experts from the Wildlife Algal-toxin Research and Response Network for the West Coast (WARRN-West) examined samples of 905 marine mammals from 13 different species. All the animals were stranded or harvested in Alaska from 2004 to 2013.

The researchers found that the harmful algae and toxins such as saxitoxin and domoic acid are present in low levels from the sample species.

Going Up North

Changes in environmental temperature have caused sea ice levels to drop and water temperatures to shoot up. Such situations, which are favorable to harmful algal bloom, are likely to expand in the northern regions. With this, the Alaskan food web may experience growing concerns in its marine food webs.

"What really surprised us was finding these toxins so widespread in Alaska, far north of where they have been previously documented in marine mammals," says lead author Kathi Lefebvre from NOAA Fisheries.

The results of the study exhibit that algal toxins are indeed going up north. Since 1998, algal toxin poisoning among sea lions is most common in Central California. The recent study is the first to record the presence of harmful algae from the south region of Alaska to the Arctic Ocean.

Impacts on Animals

Lefebvre says the team cannot determine yet whether the toxicity levels of the algal blooms can cause health threats to marine mammals in the area. She adds that it is challenging to identify the exact cause of deaths of the stranded animals, but it appears certain that the warming climate boosts algal blooms thus, increasing the possible health impacts on the marine mammals.

Implications On Human Health

The researchers confirm that the levels of harmful algae in the marine mammals are well below the limits set for seafood. However, people should not be all too complacent.

Study co-author Gay Sheffield says bearded seals and walruses may contain contaminated clams in the stomach. This means that the marine mammals, which are most commonly eaten in western and northern Alaska, may not be completely safe for human consumption.

Animal parts such as muscles and blubber, which are commonly eaten by humans, are less likely to contain toxin levels that may pose a threat to human health. So far, authorities have not made any changes in the food safety guidelines of the Alaska Department of Health.

The study was published in the journal Harmful Algae.