A field evaluation of international monitoring guidelines for the biological effects of tributyltin

The Oslo and Paris Commission (OSPAR) Guidelines for monitoring the biologi cal effects of tributyltin compounds (TBT) were evaluated using data collec ted for preparation of a Celtic Seas Quality Status Report. Two types of su rvey were undertaken: broad scale, to determine wide impacts in coastal wat ers; and localised, around representative harbours to establish ranges of e ffect from recognised input points. This evaluation indicates that results from the broad scale surveys can be used to compare different areas of coas tline. Nucella is widespread away from point sources although many individu als show some degree of imposex. Populations are generally not at risk. The localised surveys indicate that, in certain situations, the monitoring obj ectives can be met in the OSPAR Guidelines (subject to minor amendment). Cr iteria are identified for the selection of point sources suitable for monit oring under OSPAR Guidelines.