Ocean Management最新文献

The paper describes the fishery side of experiments carried out by a research team from various governmental departments and the oil and gas industry on the effects of the impacts of commercial bottom-fishing gear on a partially buried, or unburied pipeline in operational use. The experiments were held early 1984 on the NAM K7/K8 18-inch gas pipeline situated on The Netherlands Continental Shelf. It was confirmed that pipelines with the new type of coatings can endure the impacts of fishing gear without ill effects on operation or safety. The forces encountered by the fishing gear, especially the beam trawl, can be considerably reduced by specially designed adaptations of the trawl head (trawl shoes) on the lines such as those developed to avoid the hooking of marine telephone cables. The forces measured in the warps are of the same order of magnitude as those measured when the gear strikes boulders or runs into sand dunes.

This paper reviews the impact of bottom trawling — beam- or groundtrawl — on animals of the sea bed. The area of study is restricted to the North Sea, however, the final conclusions have a far wider application. Protests against the use of trawls date back to the period of their introduction; for northwest Europe this was the thirteenth century, and it still evokes protests up to the present day. Trawling does affect benthic life, the trawl penetrates up to 30 mm into the soil, depending on the substrate. All types of trawls are basically similar in their action on the bed. Beam trawls with tickler chains catch much more benthos than do ground trawls without tickler chains. Some groups of animals suffer far more damage than others, e.g. echinoderms. It is not unlikely that in the long-term a shift in species and numbers may occur along the same lines such as has been found in the German Wadden Sea where polychaetes are on the incline and molluscs and crustaceans on the decline.

The literature pertaining to the composition of produced waters and the fates and effects of these effluents in the marine environment has been reviewed. Discussions of lethal and sublethal effects have been complemented by considerations of data relating to crude oils, petroleum products, and individual constituents.

Two distinct strategies have been employed in attempts at discerning the ecological effects of produced water effluents: predictive and observational. The predictive approach involves determining the composition of the effluents and considering the toxicities of individual components in an attempt to deduce the overall toxicity of the effluent. The observational approach, although site-specific, provides direct and unequivocal information relating to ‘real-world’ effects.

By combining both the predictive approach and the observational approach, it can be concluded with a high degree of confidence that current practises for the disposal of produced waters are ecologically sound.

The approaches of three nations (U.S.A., U.K., and Canada) to environmental impact assessment for offshore developments are compared. The comparison examines the types of regulatory approaches, the general allocation of responsibilities, and the expectations that accompanied each approach. The realities of offshore impact assessment are discussed in terms of influence on decisions, the scientific integrity of assessment studies, and the difficulties of impact prediction and monitoring. The lessons learned after more than ten years of experience are summarized, and the expected influence of a recent Canadian study on the practice of environmental assessment, in Canada at least, is discussed.