A NCCOS Ecology and Oceanography of Harmful Algal Blooms (ECOHAB)-funded study at the University of Washington and the NOAA National Marine Fisheries Service laboratory in Seattle has developed a unique and convenient way to detect very low levels of exposure tothe harmful algal toxin domoic acid in laboratory zebrafish and in wild California Sea lions. Unlike available and reliable tests to measure high levels of domoic acid in shellfish there has been no convenient way to measure low levels of domoic acid exposure – until now.
The test, measuring antibodies to the toxin in the blood, can hopefully be used someday to detect long-term low-level exposure to domoic acid in humans who eat mussels and clams routinely and year-round. One surprising finding is that repeated low-level exposure does not increase tolerance to the toxin (like increasing immune system resistance to a disease) but makes the organism more sensitive to the toxin. The next step in the study will be to conduct blood tests on people routinely exposed to low levels of domoic acid from eating lots of shellfish.