Environmental effects of oil and gas exploration on the benthic fauna of the Norwegian continental shelf: an analysis using the OLF database

We will use traditional and new multivariate statistical methods to analyse effects of using oil-based and non-oli-based drilling fluids on the benthos of the Norwegian continental shelf. These methods allow one to test hypotheses of cause and effect and thus may move from a descriptive to a predictive tool. In order to do such analyses datasets will have to be selected which comply with set criteria. Most SSDs are based on laboratory data and often from non-marine species. We have started development o f field-based SSDs which show the combined effects of a variety of chemicals. plots for Ba, Cd, Cu and PAHs show encouraging results and we will plot a wide variety of SSDs for combined data and data split into sub-sets varying sediment properties and dep th.Such SSDs will be of great benefit as management tools for minimising effects on the marine environment The present monitoring programme is probably not efficient for the stated purposes. We will erect scenarios and test whether a reduced sampling pro gramme can give similar accuracy and precision in monitoring effects of the industry on the marine environment. A series of simulations will be done on selected data chosen to illustrate temporal and spatial changes. The results should be of interest to b oth environmental authorities and oil companies.