Santa Cruz, CA -- Researchers studying a bloom of toxic algae in Monterey Bay last summer found the algal toxin domoic acid in anchovies, sardines, and krill, all key species in the marine food web. Harvesting of anchovies and sardines for human consumption was halted and there were no reports of adverse effects on wildlife from this particular bloom. Nevertheless, the findings raise concerns about the potential effects of the toxin on a wide range of marine mammals and birds, said Mary Silver, a professor of ocean sciences at the University of California, Santa Cruz.
Among the animals potentially affected by the toxin are several endangered species of whales that feed in Monterey Bay on the organisms Silver found were tainted with domoic acid. While there are no documented cases of whales dying from domoic acid poisoning, the toxin was blamed for the deaths of more than 50 California sea lions in 1998.
"We know the toxin enters the food web and poses a threat to large marine mammals and seabirds, but there is still a lot that we don't know," Silver said.
Silver has been studying domoic acid and the algae that produce it since the early 1990s. She and her coworkers presented their latest findings in December at a symposium in Woods Hole, MA, on harmful marine algae.
Domoic acid, a potentially lethal neurotoxin, is produced by several species of diatoms (microscopic algae) in the genus Pseudo-nitzschia. But not all blooms of these species are toxic, Silver said. During 2000, there were several small blooms of Pseudo-nitzschia that were not highly toxic, then a large one in late August and early September that had very high toxin levels. During this bloom, anchovies, sardines, and krill (all of which feed on diatoms and other kinds of plankton) accumulated enough domoic acid to be harmful to animals consuming them.
Krill are small, shrimp-like crustaceans that play a key role in marine food webs. A wide variety of marine organisms prey on kr
Contact: Tim Stephens
University of California - Santa Cruz