BIOACCUMULATION OF PARALYTIC SHELLFISH POISONING (PSP) TOXINS FROM THE CYANOBACTERIUM ANABAENA-CIRCINALIS BY THE FRESH-WATER MUSSEL ALATHYRIA-CONDOLA

The Australian freshwater mussel Alathyria condola accumulated high le vels of paralytic shellfish poisoning (PSP) toxins when fed the neurot oxic cyanobacterium Anabaena circinalis, shown recently to contain hig h concentrations of C-toxins and gonyautoxins. Significant accumulatio n (>80 mu g/100 g of mussel flesh) was detected following 2-3 days exp osure to water containing 2x10(5) cells/ml A. circinalis. Only trace a ccumulation of PSP toxins was demonstrated over long-term (5 week) exp osure at low concentration (c. 10(4) cells/ml). The relative abundance of C-toxins, gonyautoxins and saxitoxins in mussels generally matched the toxin profiles of the dietary A. circinalis, although there were differences in the GTX2/3 and C1/2 ratios with time, and an increase i n abundance of decarbamoylgonyautoxins. Analysis of mussel tissues aft er 7 days, exposure to A. circinalis revealed that 96% of the toxins w ere accumulated in the viscera. As in marine waters, the bioaccumulati on of PSP toxins in freshwater mussels may pose a health risk to human s and animals, especially in areas where seasonally decreasing water l evels expose mussel beds to surface scums of toxic cyanobacteria.