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Algae toxins found in San Francisco Bay shellfish

Staff Writer |
A new study has shown that toxins from freshwater algal blooms, a growing problem in lakes and rivers worldwide, can also contaminate coastal waters and marine shellfish.

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Scientists have detected high levels of a toxin produced by freshwater algae in mussels from San Francisco Bay.

Although shellfish harvested from California's coastal waters are monitored for toxins produced by marine algae, they are not routinely tested for this freshwater toxin, called microcystin.

The toxin, which causes liver damage, is produced by a type of cyanobacteria (also known as blue-green algae) that thrives in warm, nutrient-rich water conditions.

It has been found in many lakes and rivers in California, including the Sacramento and San Joaquin Rivers, which flow into the San Francisco Bay Delta, and in several Bay Area lakes.

Raphael Kudela, the Lynn Professor of Ocean Health at UC Santa Cruz, said his lab investigated the potential for microcystin to contaminate shellfish after detecting low levels of the toxin in water samples from San Francisco Bay.

The researchers tested mussels collected from five sites in the Bay.

They also did experiments with both mussels and oysters in tanks to determine how quickly the shellfish take up the toxin and how long it takes to clear it from their tissues. The results are published in the journal Harmful Algae.

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