Monitoring of fate and effects of oil in the marine environment.

Examples are presented of different techniques which are in use, or could be used, to monitor the fate and effects of oil pollution in Dutch marine waters by oil spills and chronic contamination by rivers, processing water from the oil industry, etc.A number of techniques are presented to quantify the fate of oil in water, sediments and biota, and some readily available methods to monitor possible effects in the ecosystem.In Dutch coastal waters much effort is being given to airborne detection of oil at the sea surface in order to reduce pollution and to take rapid measures in cases of severe pollution. Oil concentrations in sediments and selected organisms can be monitored as a general quality control measure, and to check the functioning of licensed installations. If concentrations above background levels are found, research on possible effects should be initiated. In this context short term studies on stress-indicators are very useful. Laboratory based investigations, for example in model ecosystems, can be carried out to test hypotheses from such studies. Elevated oil concentrations and indications for ecological effects may result in changes in the management of the marine area in question. Monitoring of population dynamics and species composition, notably of benthic macrofauna, should be carried out to verify long-term effects on the ecosystem.