Richard E. Dodge

EFFECTS OF UNTREATED AND CHEMICALLY DISPERSED OIL ON TROPICAL MARINE COMMUNITIES: A LONG-TERM FIELD EXPERIMENT

ABSTRACT A multidisciplinary long-term field experiment was conducted to evaluate the use of chemical dispersants to reduce the adverse environmental effects of oil spills in nearshore, tropical waters. Three study sites, whose intertidal and subtidal components consisted of mangroves, seagrass beds, and coral reefs, were studied in detail before, during, and after exposure to untreated crude oil or chemically dispersed oil. This study simulated an unusually high (“worst case”) exposure level of dispersed oil and a moderate exposure level of untreated oil. The third site served as an untreated reference site. Assessments were made of the distribution and extent of contamination by hydrocarbons over time, and the short- and long-term effects on survival, abundance, and growth of the dominant flora and fauna of each habitat. The whole, untreated oil had severe, long-term effects on survival of mangroves and associated fauna, and relatively minor effects on seagrasses, corals, and associated organisms. Chemi...

Continuing Long-Term Studies of the Tropics Panama Oil and Dispersed Oil Spill Sites

ABSTRACT The TROPICS (Tropical Oil Pollution Investigations in Coastal Systems) oil spill experiment was conducted on the Caribbean coast of Panama, near Bocas del Toro. In November 1984, crude and dispersed crude oil were released in two separate boom-enclosed areas representative of intertidal mangrove and subtidal seagrass/coral ecosystems. The present information is based on site visits over the past two years, including 2002. Following the degradation of oil over the past 18 years, sheen identified from the spilled oil in 1994 is still visible in non-dispersed Oil Site sediments. In mangroves, previously denuded areas exposed to crude oil are currently occupied by new seedlings and saplings, which are growing rapidly but with morphological prop-root deformations. Tree mortality occurred in both the Dispersed Oil and Reference Sites, but was non-localized and appeared as natural mortality in aged trees. Recent data have revealed an invasion of seagrass beds by finger coral at the Oil Site. Since treat...

THE EFFECTS OF CHEMICALLY AND PHYSICALLY DISPERSED OIL ON THE BRAIN CORAL DIPLOMA STRIGOSA (DANA)—A SUMMARY REVIEW

ABSTRACT The Coroil project in Bermuda has been an intensive, multidisciplinary study of the effects of physically and chemically dispersed Arabian light crude oil on the main reef-building coral in Bermuda, Diploria strigosa. This paper reviews the results of this three year study. Corals were exposed to dispersed oil in a flow system, using spectrofluorimetry and gas chromatography to characterize and quantify the dose. Appropriate controls were included in all experiments. The studies included effects of dispersed oil on survival and behavior, the uptake and depuration of petroleum hydrocarbons, photosynthesis by symbiotic zoo-xanthellae, and skeletal growth. In behavioral and growth studies, corals were dosed in the laboratory or in the field. Laboratory-dosed colonies were returned to the field to determine long-term effects. Exposure to 20 ppm of chemically dispersed oil for 24 hours induced various behavioral reactions, including tentacle retraction, tissue contraction and mesenterial filament extr...