Harmful Algal Blooms
Several species of single-celled algae growing in Washington produce potent toxins that can poison marine animals or become concentrated in shellfish and sicken, even kill, humans who eat them. Even when they don’t harm humans, toxic blooms can force costly shutdowns of wild and cultivated shellfish harvests. Unfortunately, thanks in part to warming waters, harmful algae have expanded into new habitats and extended their blooming seasons. And, blooms are becoming more severe.
Washington Sea Grant (WSG) educates shellfish gatherers, shoreline dwellers, and other citizens about harmful blooms. We manage the SoundToxins program, a network of trained monitors who regularly test vulnerable waters for dangerous species of algae.
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A Who’s Who of HABs
Who are these critters that can erupt into harmful algal blooms? The HAB species that most worry Washington health officials include the following:
Alexandrium catenella, the so-called “red tide” dinoflagellate that causes sometimes-lethal paralytic shellfish poisoning (PSP), undergoes a dormant cyst state — lingering in bottom sediments — then erupts into blooms when conditions turn favorable. That’s traditionally been the warmer months, but blooms are now starting earlier, extending later into the year, and becoming more severe. This organism’s toxins can build up especially quickly in mussels, which filter high volumes of water, and may last a year or more in butter clams and non-native varnish clams.
Pseudo-nitzschia diatoms produce domoic acid, the toxin that causes amnesic shellfish poisoning (ASP). Its symptoms can be neurological, as well as gastrointestinal. ASP’s effects on seabirds in California inspired Alfred Hitchcock’s film, The Birds.
Dinophysis dinoflagellates cause the self-descriptive diarrhetic shellfish poisoning (DSP). Dinophysis floated for decades in local waters without apparent harm. Then, in 2011, three people came down with DSP after eating mussels from Sequim Bay. Sixty more fell sick in 2012 after eating mussels from Saltspring Island, Canada.
Heterosigma akashiwo, a raphidophyte, poisons fish rather than humans. Until 2014 it was only known to kill fish concentrated in aquacultural net pens. Then Jamestown S’Klallam tribal biologist Neil Harrington found hundreds of afflicted chum salmon washed up in Sequim Bay. Like Alexandrium, Heterosigma can hide dormant in sediments. Unlike Alexandrium, it can emerge whenever light and temperature conditions turn favorable. Heterosigma then swims rapidly to the surface and forms massive toxic blooms.
WSG staff, led by water quality specialist Teri King, use many strategies to help Washingtonians understand and guard against harmful algal blooms.
- WSG staff trained and coordinated 50 SoundToxins monitors deployed to 33 sites from Budd Inlet in south Puget Sound to Orcas Island and Port Angeles.
- Teri King hosts the annual Shellfish Growers Conference.
- WSG disseminates publications to the public to help them gather safe shellfish.
- WSG conducts workshops, beach walks, site visits; hosting booths at community festivals and makes presentations to professionals and the general public.
- King manages Bivalves for Clean Water, a citizen science program that the uses shellfish for monitoring water quality.
WSG supports cutting-edge research into these elusive algae, developing new ways to predict and prepare for their blooms. Specific research projects provide some answers to the following questions:
In the News
- Bioluminescence: Plankton found in Hood Canal can be seen glowing from outer space
North Kitsap Herald, August 16, 2016
- Rare algae bloom turning Hood Canal green
King 5 News, July 31, 2016
- Phytoplankton bloom turns Washington state fjord milky
United Press International, July 29, 2016
- NASA Satellite Spots More Green Water, This Time in Washington State
The Weather Channel, July 28, 2016
- Bloom in Hood Canal, Washington
Earth Observatory, July 24, 2016
- Nasty HABits
Increasingly toxic algal blooms in Washington’s waters threaten consumers, shellfish growers, fish farmers, even birds and salmon. Read how WSG field agents and researchers are deploying innovative strategies to monitor harmful algae in WSG’s Spring 2015 newsletter.
- Gathering safe shellfish in Washington: avoiding paralytic shellfish poisoning
Learn to a be safe shellfish gatherer using this classic guide by WSG reseachers and staff.