Thomas G. Ballou

Effects of dispersed oil on mangroves synthesis of a seven-year study

Abstract The results of a long-term program to determine the effects of oil and dispersant on red mangroves and black mangroves are presented. Laboratory experiments were conducted to determine the effects of three oils and dispersant on juvenile red mangroves and black mangroves. A field experiment was conducted to determine the effects of a crude oil and dispersant on a mature mangrove forest in Panama. Our studies indicate that exposure of mangrove seedlings to oil and dispersant in the laboratory resulted in changes of growth, respiration, and transpiration, and led to uptake of petroleum hydrocarbons. Exposure of a mature red mangrove forest to oil and dispersant resulted in many of the same effects observed in the laboratory and at other oil spill sites. These effects were greatly reduced at the site treated with oil and dispersant when compared to the site treated with whole oil.

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...

PRELIMINARY RESULTS OF LABORATORY TESTING OF OIL AND DISPERSANTS ON MANGROVES

ABSTRACT Relatively few data exist on the effects of oil and dispersing agents on tropical wetlands. This is true despite extensive near-shore and onshore drilling, onshore refining, and transporta...

FIELD EXPERIMENTS ON THE EFFECTS OF OIL AND DISPERSANT ON MANGROVES

ABSTRACT Field experiments were conducted to determine the effects of oil and dispersant on red mangroves (Rhizophora mangle). Two experimental sites were chosen on the basis of their biological and physical similarity and treated with either undispersed Prudhoe Bay crude oil or with Prudhoe Bay crude and dispersant Corexit 9527. Short- and long-term effects on biota were monitored to determine the effects of using dispersants on spilled oil in mangrove forests. Significant differences were noted in effects on seedling and adult mangroves, most notably in survival and growth of adults. Undispersed oil caused significantly lower survival and growth of seedlings, and significantly lower growth and foliage cover in adults. Addition of dispersant to crude oil greatly increased its mobility in the water column, and decreased its residence time in the intertidal zone. Retention of oil within the mangrove forest was the primary factor in controlling impacts to mangroves, and dispersants appeared to greatly reduc...

MAPPING THE DISTRIBUTION OF PROTECTED AND VALUABLE, OIL-SENSITIVE COASTAL FISH AND WILDLIFE

ABSTRACT An approach has been developed to produce a map series that displays known, pertinent information concerning the distribution, seasonality, and habits of protected and valuable coastal fish and wildlife that are sensitive to oil spill impacts. This involves a compilation of all literature on the protected and oil-sensitive fish and wildlife for a region. Distribution and abundance data are then evaluated for each species, and all point localities, aggregations, and home ranges are shown on maps. These data include marine mammal haul-out and pupping areas, terrestrial mammal feeding areas, marine bird rookeries, salmon and herring streams and intertidal spawning sites, marine turtle nesting beaches, and intertidal shellfish beds. Aerial surveys are then made of the sites located during the literature search to verify the mapped literature data, as well as to add new wildlife localities. Information on the species, their distribution and ecological type, their habits, and seasonality is color coded...