HAB Research: NWFSC HAB Research

Toxicology Studies

A Proposed Mechanism of Domoic Acid Retention in the Pacific Razor Clam (Siliqua patula)

Most molluscan shellfish accumulate and then rapidly excrete domoic acid. Razor clams in Washington State, on the other hand, retain very high levels of DA (e.g., 400 ppm) for very long periods (e.g., 6 months or more). To date, no deleterious effects of domoic acid have been noted in these clams. Research has shown that these shellfish have glutamate receptors, the putative site of action for domoic acid toxicity. The question that we are going to answer is how these clams continue to function normally in spite of these high levels of domoic acid. The purpose of these studies is to help us understand how and why domoic acid is retained in these clams. This project is funded by the ECOHAB program.

A molecular basis for differential susceptibility and accumulation of paralytic shellfish poisoning (PSP) toxins in commercial bivalves

PSP blocks sodium channels and causes paralysis. In areas that have a history of PSP, clams appear to have developed a resistance to PSP toxins. Clams from such areas have been observed to have the capability to burrow in the sand and exhibit an 'escape' or 'avoidance' response to the toxic cells. On the other hand, clams in areas that have limited exposure to PSP appear to lack this burrowing behavior and avoidance mechanism. Is there a genetic component responsible for this behavioral difference between resistant and non-resistance clams? This project is funded by the ECOHAB program.

Effects of Algal Toxins on Early Development in Larval Fish

It is well established that the dietary uptake of toxins produced during harmful algal blooms can kill fish. However, the chronic effects of sublethal exposure to dissolved toxins (toxins in free seawater) are poorly understood. Potential impacts on the embryos and larvae of marine free-spawning fish are a major concern because these sensitive developmental stages may be unable to avoid the dissolved toxins that algal cells release into the surrounding water during HABs. These toxins may have long lasting effects on developing fish that negatively impact recruitment, survival, or reproductive success at later life history stages. Our aim is to identify sublethal indicators of developmental toxicity caused by dissolved-phase toxin exposure that may ultimately affect the productivity of marine fish populations. This project is funded by the ECOHAB program.