Harmful Algal Blooms

NOAA tools for protecting people, food, and the environment

By Craig Collins

If you’re an outsider visiting one of Washington state’s intertidal beaches on a fine spring day, you might not know what you’re looking at: dozens or even hundreds of people clad in waders, tramping about in the surf, bent in intense study of the shallows – and occasionally plunging shovels or long steel tubes into the sand.

An algal bloom in Lake Erie.

These are clam diggers. The Pacific razor clam is a delicacy so prized by Washingtonians that in normal times up to a thousand people may crowd onto a single mile of beach, each seeking their daily bag limit of 15 clams. The clam stocks for recreational digging are managed carefully by the Washington Department of Fish and Wildlife (WDFW) – and one of the biggest challenges in managing them is the frequency of harmful algal blooms (HABs) along the Washington and Oregon coasts that produce the neurotoxin domoic acid, which can build up in filter-feeding shellfish to poisonous levels. Since the toxin was first detected on the Pacific coast in the 1990s, the state’s razor clam seasons often have been disrupted by closures.

In April of 2017, WDFW decided, for the first time ever, to increase the bag limit on razor clams. Over 11 days in April and May, the state’s largest managed beach, Long Beach, was visited 77,800 times. The unprecedented decision was informed by science: the NOAAfunded Pacific Northwest HAB Forecast and Monitoring System, which monitors offshore and beachside ocean conditions, helped the agency to predict a future spike in algal toxins that would probably force the closing of the fishery for the remainder of the season. The diggers who flocked to the beach to take advantage of the shortened season generated $7 million in local revenue.

Harmful algal blooms happen when colonies of algae, often fed by warm temperatures and nutrient runoff from land, grow out of control and produce toxins. Not all algal blooms are toxic, but even nontoxic species of algae can be harmful if they grow unchecked, consuming all the oxygen in the water and smothering fish, invertebrates, corals, or aquatic vegetation. For a number of reasons, including higher temperatures in our atmosphere, oceans, and lakes, HABs are a growing problem in every U.S. coastal and Great Lakes state. In the fall of 2019, on Florida’s Gulf Coast, a highly concentrated “red tide,” a bloom of the species Karenia brevis, produced toxins that killed millions of fish and eels, hundreds of dolphins and sea turtles, and countless birds.

In fresh water – such as Florida’s Lake Okeechobee or the Great Lakes, where harmful algal blooms are frequent – different species of blue-green algae, or cyanobacteria, produce toxins that can contaminate drinking water supplies or food species. Sometimes the level of toxins in the water is high enough that it can make people sick with respiratory or gastrointestinal symptoms when they drink or swim in it

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Red tides and cyanobacteria blooms are also costly. By September of 2019, the Gulf Coast red tide had already cost business owners an estimated $90 million. When Washington state was forced to shut down its razor clam harvest in 2015, it cost the state $40 million in tourism dollars. Cyanobacterial blooms are estimated to have caused economic losses of more than $1 billion over the last several decades to coastal economies that rely on recreation, tourism, and seafood harvesting.

There’s no proven way to prevent a HAB event, but NOAA works on several fronts to mitigate the threats they pose to the nation’s health, ecology, and economy. Federal law charges NOAA with advancing science and our nation’s ability to detect, assess, and predict HAB events, and it does this mostly through the programs of its National Centers for Coastal Ocean Science (NCCOS), which had developed the Algal Bloom Monitoring System to deliver real-time products for locating, monitoring, and measuring algal blooms in coastal and lake regions.

Public warning signs appear in areas that have been closed due to high levels of toxin in shellfish.

The agency’s HAB forecasts help members of the public make informed decisions, such as closing fisheries or recreational areas, or closing off drinking water intakes. A community-based network of volunteers, the National Phytoplankton Monitoring Network, collects important data about species composition and distribution that enhances the nation’s ability to manage and respond to the growing threat posed by HABs. NCCOS also maintains two rapid response capabilities, the Analytical Response Team and the HAB Event Response Program, aimed at helping state and local officials make informed decisions for mitigating the impacts of HABs to wildlife, human health, and commerce.

NOAA currently uses a combination of satellite imagery and water samples of the algae species Karenia brevis collected from the field by local partners to forecast the location and intensity of red tide events. The conditions reports for red tide in Florida and Texas are available to the public and give respiratory irritation forecasts by coastal region.

The federal law that authorizes these responsibilities also establishes a comprehensive research program: competitive grants, administered by NCCOS, supporting investigations that promise to increase our ability to understand, mitigate, and perhaps prevent HAB events – including investigations of new technologies.

NOAA GLERL researchers Danna Palladino and Duane Gossiaux and vessel operator Kent Baker deploy an environmental sample processor (ESP) to measure water toxins in Lake Erie’s harmful algal bloom, July 17, 2019.

Some emerging technologies are already being explored by NOAA experts. In the summer of 2019, scientists at NOAA’s Great Lakes Environmental Research Laboratory (GLERL) experimented with uncrewed underwater vehicles, or gliders – torpedoshaped robots that collect water samples for analysis – in western Lake Erie, where three gliders circulated near municipal water intake pipes throughout the season. These unmanned systems likely will become another tool in NOAA’s arsenal for tracking and detecting HABs, giving the public fair warning of their hazards and helping to protect people, food, and water resources.