A Study of Intertidal and Shallow Water Macroinvertebrate Populations Exposed to an Oil Spill on Horn Island, Mississippi

Heard, Richard; McLelland, Jerry

On Monday, September 18, 1989, a Chevron Oil pipeline near the mouth of the Pascagoula River, Mississippi, was ruptured during dredging operations. An estimated 4,200 gallons of crude oil (about 130 barrels) were released into the vicinity. The pipeline was turned off and the spill was more-or-Iess contained with oil confinement booms. Apparently, the confinement system broke loose and oil drifted southwestward onto Hom Island before it could be retrieved, resulting in a relatively small-scale beach impact Wednesday night, September 20. The following day, September 21, personnel of the Gulf Coast Research Laboratory's (GCRL)Invertebrate Zoology Section conducted a preliminary survey of the affected area by collectingbeach and intertidal infaunal samples (see Appendix I for GCRL field notes, and Appendix IIfor results of qualitative samples collected). The spill affected a wide-spread area on the northside of Hom Island, mainly at the mid and western end, with the largest concentration being an approximate 3/4 mile section at the Big Lagoon area near the center of the island. At the most heavily oiled areas, oil had soaked from 12 to 20 cm into the sand along the beachface. During the weeks following the spill, the oiled beach was washed with water from high pressure pumps in order to resuspend the oil for easier pickup. Clean-up operations were completed by Chevron and its contractor, Thompson Environmental, by mid October of 1989. A more detailed description and chronology of the Horn Island spill and subsequent clean-up operations is provided in the National Park Service's "Case Incident Record" by USNPS Ranger Robert Thomas in Appendix IT of the Phase I Report.