SEASONAL FLUCTUATION OF ORGANOCHLORINES IN MYTILUS-EDULIS L FROM THE SOUTH-WEST BALTIC SEA

Seasonal and spatial variations in organochlorine concentrations in mu ssels Mytilus edulis from the Baltic Sea were assessed The mussels fro m highly contaminated harbour areas showed a strong short term fluctua tion ill comparison to mussels from less contaminated beach areas. In all observed stations, PCB concentrations increased during autumn and decreased during early and late summer Their change correlated positiv ely with their lipid content. The reduction of the residue level durin g summer could be related with spawning activity. During winter the ch ange in PCB concentration in observed stations were not uniform The st rongly elevated accumulation during winter, which was found at most ha rbour stations, may be caused by diminished filtration activity due to increased stress. The pattern of seasonal change expressed on a dry w eight and lipid weight basis was different. The change of PCB concentr ation on a lipid basis resulted from a dilution effect during seasonal lipid accumulation and a concentration effect during utilisation and release of body lipids On a lipid weight basis therefore the actual ex change of organochlorines in mussel tissue can not be observed. Copyri ght 1996 Elsevier Science Ltd