Design and Implementation of a Mesocosm Experiment On The Environmental Consequences of Nearshore Dispersant Use

Abstract

In April 1998 the first full-scale oil spill experiment was run at the Coastal Oilspill Simulation System (COSS) Facility in Corpus Christi, Texas. The facility contains nine 110-foot long, eight-foot deep wave tanks for simulated nearshore or intertidal habitat experiments. Features include an adjustable 2-foot tidal range, variable flow rate, and random wave capability. Sediment can be added to create bottom habitat and to develop an intertidal “shoreline.” The project compared the ecological effects when oil is allowed to strand on the beach to the effects when dispersed oil is present in very shallow areas. Untreated and dispersed weathered Arabian Medium crude oil was released in three tanks each. Two other tanks served as controls. The fate and effects of the oil or dispersed oil were evaluated over ten days using caged marine species and detailed hydrocarbon chemistry. The tests were successfully completed, demonstrating the facility's impressive potential for similar experiments. Preliminary data analyses indicate that water column effects of dispersed oil were not significantly different from those of untreated oil, and the use of dispersant led to a clear reduction in shoreline accumulation of oil.