On May 31, investigators funded by the National Centers for Coastal Ocean Science released the second annual map of Alexandrium catenella cysts in bottom sediments throughout Puget Sound in the state of Washington. They found that the highest cyst concentrations at Bellingham Bay in the north and Quartermaster Harbor in the south, similar to 2011. This year’s cyst abundance in the Puget Sound is considerably lower than last year, the scientists announced.
A map for a different species of Alexandrium‘s cysts in the Gulf of Maine forecasts the size and severity of the following year’s blooms, so University of Washington investigators are testing a similar version for the Puget Sound. If successful, it will allow shellfish growers and gatherers to harvest before blooms reach their beds. The map can guide shellfisheries to avoid areas with a history of blooms. It will also help state officials pinpoint where to monitor beds, which saves them money.
This dinoflagellate (a type of plankton) produces powerful toxins that accumulate in shellfish, which feed by filtering plankton and other material from the water. Rigorous monitoring and harvesting closures prevent Paralytic Shellfish Poisoning in people who buy or harvest oysters, clams or razor clams to eat.
As blooms recede, some Alexandrium cells form small, seed-like cysts which fall to the bottom of the Puget Sound where they overwinter and then germinate in the spring. Under the right conditions, they can bloom again in large numbers. These maps of cyst abundance are like NOAA’s annual hurricane season forecasts, they don’t predict day-to-day conditions, but they help local and state officials prepare for the coming summer.
This project was featured in an NPR blog post in March 2012.