The effects of oil spills and dispersant use on corals

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.