For the GEEP Workshop, 4 indoor mesocosms at the Marine Research Station Solbergstrand were stocked with equal numbers of Platichthys flesus, Carcinus maenas, Mytilus edulis, httorina littorea and Nucula tenuis as well as subtidal soft bottom sections taken with an USNEL box corer. For 4 mo prior to the workshop, 3 of the basins were continuously exposed to a mixture of diesel oil (125.32 and 6 pg 1-' total hydrocarbons in the water) and copper (nominal 20, 5 and 0.8 pg 1-' Cu2+), with the fourth mesocosm basin as a control (measured total hydrocarbons of 3 pg I-'). Sediment sections were sampled by corers for community fauna1 analysis prior to the workshop; sampling of N. tenuis and epifauna was carried out during the workshop.