DEPURATION OF DOMOIC ACID FROM LIVE BLUE MUSSELS (MYTILUS-EDULIS)

Industrial depuration may provide a means of removing domoic acid toxin from blue mussels (Mytilus edulis). Mussels containing up to 50-mu-g domoic acid.g-1 were transported from a Prince Edward Island estuary into controlled laboratory conditions to test the effects of temperature, salinity, mussel size, and feeding upon depuration. Fifty percent of toxin was eliminated within 24 h. After 72 h, mussels were either clean or contained, on average, only residual levels of toxin (< 5-mu-g.g-1), regardless of conditions. Exponential depuration curves were fitted to the domoic acid concentration data. To evaluate differences in rate of depuration under various conditions, statistical comparisons were made between slopes of the clearance curves. Rates of depuration were faster in small (45-55 mm) than in large mussels (60-70 mm) and more rapid at 11 than at 6-degrees-C. There was no significant difference in depuration rate at 18 parts-per-thousand salinity as opposed to 28 parts-per-thousand or in starved versus fed mussels. Because of their relatively large digestive glands, meats of small mussels contained more toxin per unit weight than meats of large mussels. The bulk of domoic acid appeared to reside in the gut lumen. However, the presence of small amounts of domoic acid in intracellular compartments cannot be ruled out.