Some conclusions regarding long -term biological effects of some major oil spills

Abstract

Many of the world ’s major spills exhibit long-term consequences, associated mainly with lagoons, estuaries and marshes. This is due to the persistence of oil or petroleum fractions in these low-energy environments. The bioavailability of residual oil to infauna is influenced by several factors, such as solubility in water, feeding habit, weathering rate and sediment grain size. The time-courses for these long-term effects vary, but may run into decades for some community perturbations. The effects are at all levels of organization, including cellular, organismic and the community. Although the number of documented long-term effects is small, they involve a wide range of biological processes: development, genetic, growth, feeding and assimilation, photosynthesis, recruitment and fecundity, and community stability. It is important to note that the known effects are probably only representative of a much wider range of possible disorders that have occurred, but which have not been detected. This is due mainly to the selective nature of spill follow-up studies. Long-term spill consequences are generally local phenomena and so far no single spill has, to our limited knowledge, significantly altered entire ecosystems or materially affected fisheries. The combination of several spills can, however, place considerable stress on an environment. Also, so far there is no indication of an increasing mutagenic or carcinogenic load in the marine environment due to biologically active petroleum fractions or to carcinogenic or mutagenic metabolites. There is, however, the possibility of local build-up of these compounds, as in ‘hydrocarbon sink’ areas, where such a burden may become a local problem .