Physico-chemical and biological features of a drilling site in the North Sea, 1 year after discharges of oil-contaminated drill cuttings
Daan, R.; van het Groenewoud, H.; de Jong, S.A.; Mulder, M. (1992). Physico-chemical and biological features of a drilling site in the North Sea, 1 year after discharges of oil-contaminated drill cuttings. Mar. Ecol. Prog. Ser. 91(1-3): 37-45
Stebbing, A.R.D.; Dethlefsen, V.; Carr, M. (Ed.) (1992). Biological effects of contaminants in the North Sea: Results of the ICES/IOC Bremerhaven Workshop. Marine Ecology Progress Series, 91(1-3). Inter-Research: Amelinghausen. 361 pp., more
In the framework of the Paris Convention for the prevention of marine pollution, the Dutch government initiated a research programme on environmental effects of discharges of contaminated drill cuttings from platforms in the North Sea. Chemical analyses of the sediment over a transect in the residual current direction revealed a clear gradient in contamination levels, with oil concentrations ranging from 250 to 450 mg kg super(-1) dry sediment within 250 m and gradually decreasing to <20 mg kg-1) beyond 750 m. Barium concentrations showed a similar pattern. Subtle biological effects, indicated by the absence of a very sensitive species (Montacuta ferruginosa), were found as far as 2 km from the discharge site. Abundance patterns of 2 other sensitive species (Harpinia antennaria and Callianassa subterranea) suggested environmental stress to occur up to 1 or 2 km. Within 750 m from the discharge site an increasing number of species, including the dominant Amphiura filiformis, appeared to decrease in abundance, successively resulting in a reduced total macrofauna abundance and species richness. Typical opportunistic species were observed more frequently only within a radius of 250 m. An alternative measure of diversity ('relative macrofauna abundance') was introduced and its merits are discussed.
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