Dispersant use for Tropical Nearshore Waters: Jamaica

Abstract

Jamaica's shoreline is at the intersection of five major petroleum tanker shipping routes, and is a cargo transshipment point for the Caribbean. The natural coastline resources are valuable economically, with two-thirds of exchange dollars coming through tourism associated with beaches, clear waters, coral reefs, and nearshore fishing. The most thorough examination of the feasibility of using dispersants ever carried out in a developing nation has been undertaken. Dispersant toxicity of various species of critical matrix organisms has been carried out with an array of 12 dispersants. Corals, fish, seagrasses, and mangroves were tested. Toxic dispersants and three very low toxicity compounds were identified at concentrations ten times those likely to occur and ten times longer exposures. Thus, a safety factor was built in. A sensitivity map of the coastline was constructed. Simulations of “near-miss” tanker accidents were done manually with disperse and nondisperse options. A policy study of European and North American dispersant use was undertaken by the Office of Disaster Preparedness, the Coast Guard and the Oil Spill Committee. A draft policy was prepared for nontoxic dispersant use. The recommendations for use of nontoxic dispersants—with primarily coral reef and fish sensitivity as paramount concerns—are Cold Clean, Corexit 9550 and Finasol OSR7. Several European nations also have approved lists with Corexit 9550 (or allied products) and Finasol OSR-7. A computer simulation of all potential occurrences is the future goal.

Ecotoxicology of tropical marine ecosystems

“…However, 10 years later coral coverage at the dispersed‐oil site was the same as or greater than at the untreated site [60]. Newly developed dispersants might be less toxic to corals [228].…”

Spectral reflectance of Thalassia testudinum (Hydrocharitaceae) seagrass: low salinity effects

“…These phases have been recognized in many toxicity tests by others and by us and are like the steps of blade senescence that occur every 15-22 d, even in young, immature plants. We have found by incubation with various toxicants over various time periods that blade yellowing and browning precedes death of the plant (Thorhaug, 1971;Thorhaug et al, 1989). Here, browning and necrosis resulted in a clear change in the shape of reflectance spectra for Thalassia blades (Fig.…”

“…We have found by incubation with various toxicants over various time periods that blade yellowing and browning precedes death of the plant (Thorhaug, 1971;Thorhaug et al, 1989). Browning blades included about 30% (mature blades at 16 ppt after 24 h) have some chlorophyll and appear yellow with brown spots and a greenish tint), but most blades are yellow-brown and translucent.…”

“…Between test incubations, plants were kept in culture for several days in normal Biscayne bay seawater (32 ppt). A 24-h (representing two Atlantic tidal cycles) incubation was based on previous laboratory data showing that a 72-h exposure to lethal factors, including salinity, was a critical period for mortality for Thalassia (Thorhaug, 1971(Thorhaug, , 1974aThorhaug and Marcus, 1981;Thorhaug et al, 1989). Incubation light cycles were 12 h light, 12 h dark greenhouse natural daylight.…”