Crude oil spilled in an estuarine marine environment caused short term, acute effects on salt marsh plants. Drastic changes in both diversity and numbers in the fish population were observed immediately after the spill. Initially zooplankton populations dropped, accompanied by phytoplankton blooms. As the oil dissipated, the zooplankton population increased rapidly. Long-term effects on fauna and flora were being studied. Migration of the oil via benthic animals and tidal percolations was observed as much as 42 cm beneath the sediment surface. The sediments acted as an organic sink preserving the crude oil. Gas chromatographic analyses of sediment core sections indicate slow degradation of the crude oil with loss only of the lower molecular weight hydrocarbons after twelve months.