Thomas D. Sleeter

Coral calcification rates by the buoyant weight technique: Effects of alizarin staining☆

The buoyant weight method has been used in a laboratory experiment over an 18-day period to assess effects of alizarin staining on the calcification rate of the hermatypic coral Diploria strigosa (Dana). Exposure of corals to a concentration of 10 mg/l alizarin for 24 h in a flow-through system caused a significant depression in calcification for a period of up to 6 days. It is suggested that such initial calcification depressions after staining could affect absolute growth measurements and cause synergistic effects with experimental manipulation of environmental conditions unless an appropriate recovery period is allowed.

The effects of oil spills and dispersant use on corals: A review and multidisciplinary experimental approach*

Coral reefs are environmentally and economically important ecosystems. The present frequency of oil spills in tropical seas may threaten coral reef survival. Some of the research to date suggests oil and dispersed oil is toxic to corals, but few experiments have tested realistic spill concentrations and exposure times. This paper outlines an experimental design which includes a flow-through laboratory dosing and seawater system, comparative laboratory and field experiments, real-time measurements of water accommodated fraction (WAF) of oil in seawater and coral tissue, and non-destructive bioassays to allow repetitive data collection from the same specimens. A major emphasis is long-term effects on growth and histology. Short-term bioassays reveal temporary effects followed by recovery generally within one week. Although no long-term effects on coral growth are detectable at this stage, histology and growth studies are not yet complete.

The effects of oil and oil dispersants on the skeletal growth of the hermatypic coral Diploria strigosa

Specimens of the hermatypic coral species Diploria strigosa were exposed to various concentrations (1–50 ppm) of oil or oil plus dispersant for 6–24 h periods in four laboratory and two field experiments. After dosing, corals were transplanted to, or left in, the field and recollected approximately one year later for extension (linear) growth analysis by the alizarin stain method. The experiments were designed to assess the long-term effects of brief low-level concentrations of chemically dispersed oil and oil alone on corals in a situation, for example, where an oil slick (treated and non-treated with dispersants) passes over a reef. No significant differences between extension growth parameters (Septa increase, Columella increase) and a calical shape parameter (New Endotheca Length) of treated corals versus controls were found in any of the experiments. In two summer experiments calical relief (Fossa length) was found to be depressed in corals of some of the experimental treatments.

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...

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...

CASE HISTORY: THE GROUNDING OF THE M/T TIFOSO, 1983—A TEST OF BERMUDA'S CONTINGENCY PLAN

ABSTRACT On January 20, 1983, the Liberian-registered 138,823 dwt vessel M/T Tifoso stranded on the northeast reef line of the Island of Bermuda at 32°28′25″ N, 64°46′08″ W. The ship was in ballast and contained approximately 450 tons of No. 6 fuel oil and 300 tons of No. 2 fuel oil and lubricating oil. Bermuda had developed an oil spill contingency plan in 1980, but this incident was the first major threat to the islands marine environment and the first test of the plan. This paper outlines the events leading to the spill, the state of readiness of a small island with a tourist-based economy, the contingency plan, and the response. Due to a previous arrangement with the U. S. government, the U. S. Coast Guard Atlantic Strike Team responded with equipment and personnel. Using additional equipment and personnel based on Bermuda and also U.S. Coast Guard pumps, most of the bunkered oil was removed (approximately 470 tons) and contained within 48 hours of grounding. Because of the existence of the contingen...

OIL SPILL CONTINGENCY PLANNING AND SCIENTIFIC SUPPORT COORDINATION IN BERMUDA: A SUCCESSFUL MODEL

ABSTRACT A complete oil spill contingency plan has been developed together with environmental sensitivity maps, a damage risk assessment, and a scientific support coordination plan. The contingency...