Last Friday, Washington State health officials reported the first U.S. illnesses linked to a single strain of toxin triggered by an algal bloom. Three people came down with Diarrhetic Shellfish Poisoning (DSP) after dining on mussels from Sequim Bay, in the Strait of Juan de Fuca.
While the culprit biotoxin had not been detected previously at unsafe levels in U.S. shellfish, thousands of people in Europe, Asia and South America have also suffered its unpleasant gastrointestinal symptoms recently.
Harmful algal blooms, known as red tides, may occur naturally in both marine or fresh waters, and have been recognized as public health threats since well before humans began altering the environment.
Many experts however suggest that some of the toxins released by various algae species are becoming increasingly prevalent and virulent across the U.S. from the Oregon coast to Chesapeake Bay.
Superfluous nutrients entering the waterway, such as fertilizers, pet waste and sewage, might also contribute to the proliferation of the microscopic marine plants.
While experts expect climate change to bring both warmer waters and episodes of heavier rains, they are wary to make a direct link between global and local phenomena. The role of pollution, and why these microorganisms produce the poisons in the first place, remains unclear as well.
What is clear however is that the Pacific Northwest is getting inundated with the toxins and their consequences: DSP joins the region’s potentially fatal PSP and amnesic shellfish poisoning (ASP) strains.
That Florida Red Tide manufactures a biotoxin which can cause near-fatal Neurotoxic Shellfish Poisoning (NSP) through ingestion as well as respiratory troubles through inhalation, in addition to killing fish, marine mammals and seabirds.
Researchers are just now beginning to understand why the algae excrete the physiologically taxing toxin?” One research lab discovered that the nutrients associated with man-made activities, like sewage and agricultural fertilizer, only cause certain species of algae to become more toxic.
That knowledge could increase researchers’ ability to monitor coastal areas, and quickly shut them before an algal bloom starts causing harm.
This could also allow lucrative fisheries to stay open longer. California, for instance, shuts down all coastal areas for recreational mussel harvesting between May and October as a precaution. In the Pacific Northwest, many Native Americans living off of Sequim Bay sell shellfish for subsistence.