Scientists Study Toxic Algal Bloom

Ocean Acidification, Toxic

NOAA Fisheries’ Northwest Fisheries Science Center has mobilized extra scientists to join a fisheries survey along the West Coast to chart an extensive harmful algal bloom that spans much of the West Coast and has triggered numerous closures of important shellfish fisheries in Washington, Oregon and California. The bloom involves some of the highest concentrations of the natural toxin domoic acid ever observed off the Central Oregon Coast.

While localized blooms of marine algae that naturally produce domoic acid are common in spring, the bloom that began earlier this year has grown into the largest and most severe in more than a decade. Sardines, anchovy and other fish that feed on the algae and other microorganisms known as plankton can accumulate the toxin, in turn poisoning birds and sea lions that feed on them. State agencies monitor toxin levels closely and impose harvest closures where necessary to ensure that all commercial seafood remains safe to eat.

Bell M Shimada noaaNOAA Fisheries and others are also developing advanced robotic systems and models to better detect and forecast harmful algal blooms. The fisheries survey left from Newport on Monday aboard the NOAA research ship Bell M. Shimada. The additional scientists will examine levels of marine toxins and the organisms that produce them. The researchers will collect samples of water, the microscopic diatoms that produce domoic acid and another form of marine microorganism that produces another type of toxin called paralytic shellfish toxins or (PSTs) that have also been detected in some shellfish.

Domoic acid and PSTs are rarely found in shellfish at the same time, but they have been this year. The scientists will also sample plankton-feeding fish such as anchovies and sardines that concentrate the toxins and transfer them to other marine animals. Officials in Oregon have halted all shellfish harvesting from the Columbia River south to Tillamook Head and closed the entire state coastline to razor clamming because of elevated levels of domoic acid. High levels of PSTs have led to the closure of mussel harvesting along the Oregon Coast north of Gold Beach. All coastal Washington beaches have also been closed to razor clamming, at an estimated loss of more than $9 million in revenue for coastal communities in the last month alone.