Biotoxin outbreak impacting California coast sea life

Blog_cocklesThe spread of algal blooms along stretches of the California’s Central Coast has produced an outbreak of a deadly biotoxin, and resulted in the deaths of large numbers of marine animals.

Scientists have identified the marine biotoxin domoic acid as the culprit in the outbreak. Domoic acid is produced by algae and accumulates in shellfish and small fish, which are then eaten by sea lions, otters, sea birds and humans, among others. Along the California coast, the effects have included numerous sea lions suffering seizures and dying, and pelicans dropping dead from the sky.

In humans, the clinical toxicological effects attributed to domoic acid can include permanent loss of short-term memory, nausea, vomiting, headache, disorientation and loss of balance. Domoic acid poisoning in humans is often referred to as amnesic shellfish poisoning, or ASP, because it is often associated with eating contaminated shellfish.

According to a report in Al Jazeera America: “The danger lies in the accumulation,” said Clarissa Anderson, one of the marine scientists in Santa Cruz tracking the growth of domoic acid events. “It’s not horribly toxic unless it accumulates at high levels.” But Anderson says that concentrations reached dangerously high levels this spring all over the California coast.

Scientists have shown that shellfish and fish don’t apparently experience any ill effects from ingesting and accumulating the toxin — but once this accumulated toxin is ingested by mammals or birds, especially, it interferes with nerve signal transmissions in the brain.

According to the Northwest Fisheries Science Center, the first reported outbreak of domoic acid poisoning in humans occurred in 1987 when shellfish from Prince Edward Island Canada were consumed. In that outbreak, three people died and over 100 people developed various toxic symptoms.

Researchers have said the dramatic increase in human activity along the coast in the past decades has led directly to the dramatic increase in the size and duration of the algal blooms along the coast. As indicated in the Al Jazeera article, “the amount of nitrogen contained in fertilizer sold in California has increased by 800% since the 1940s, contributing to the hefty 800,000 tons of nitrogen used as fertilizer every year.” It is this increase in nitrogen that fuels the increased algal blooms, say scientists.

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