Tributyltin inputs to the North Sea from shipping activities, and potential risk of biological effects

Abstract

The mechanisms leading to an annual input of tributyltin (TBT) to the North Sea from skipping are discussed. It is estimated that the gross annual input of TBT to the North Sea was 68 tonnes. A simple numerical model of the North Sea has been applied to the input data, and indicates that greatest risk of biological effects of TBT from commercial vessels would be expected in areas of the south-eastern North Sea (NSTF Areas 4, 5), and off eastern England (Area 3ii). Low intensity of impact was indicated in the northern (Areas 1, 2, 3i) and north-central (Area 7i) North Sea. The sensitivity of the model output to variations in critical parameters of the behaviour and inputs of TBT are discussed, and are found to have minor effects on the overall conclusions. The estimates of relative risk of biological effects from TBT broadly reflect the impacts observed in dogwhelks (Nucella lapillus L.) in North Sea coastal areas.