Seasonal fluctuations of tributyltin (TBT) and dibutyltin (DBT) in the dogwhelk, Nucella lapillus (L.), and the blue mussel, Mytilus edulis L., in Icelandic waters

Seasonal levels of tributyltin (TBT) and dibutyltin (DBT) were analysed in the dogwhelk (Nucella lapillus) and the blue mussel (Mytilus edulis) from south-western Iceland. Seasonal fluctuations of TBT were observed in both dogwhelk and blue mussel, with summer levels being approximately five (dogwhelk) to ten (blue mussel) times the winter levels. These changes were related to seasonal activity in feeding and resting of the dogwhelk and feeding of the blue mussel, while seasonal changes in shipping activity were insignificant. This indicates that maximum levels of TBT pollution should mainly be monitored in these animals at high latitudes during late summer or early autumn.