Relationship of Spartina alterniflora growth to sediment oil content following an oil spill

A single spill of crude oil in a salt marsh is generally considered to have limited biological effects. A crude oil spill in Dickinson Bayou (in the Galveston Bay system of Texas) in January 1984 provided the opportunity to test this hypothesis in salt marshes exposed to varying amounts of oil. Growth of Spartina alterniflora was unaffected in light to moderately oiled sediments (less than 5-mg oil/g sediment). However, growth was significantly reduced in sediments with high oil content (5 to 51 mg/g) through 18 months. Erosion of shoreline areas with high oil content was evident by 16 months and continued through 32 months. These results demonstrate the adverse effect of high concentrations of crude oil in salt marsh sediments. Each crude oil spill must be evaluated individually with regard to the likelihood of significant accumulation of oil in sediments before a decision is made regarding a cleanup response.