Hydrocarbon-based communities in the North Sea?

Abstract

Abstract Surveys of submarine pipeline routes, platform sites, and the seabed in the North Sea indicate that hydrocarbon-based communities occur in connection with gas-related seabed features, that is pockmarks and ‘mottled’ seabed. Sediments beneath the larger patches of ‘motlled’ seabed are gas-charged and it is assumed that slow seepage (micro-seepage) of pore-water and hydrocarbons occurs from these. The smaller patches named ‘eyed pockmarks’ are also suspected to represent gas-seepage locations. The distribution of the benthos, nekton, and plankton associated with ‘mottled’ seabed in the Tommeliten area and specific pockmarks in the Holene and Gullfaks areas was studied by video-tape recordings. Besides the faunal elements, biogenic sedimentary structures were recorded. A remarkable visible difference between the environment outside and inside the ‘mottled’ seabed areas and the pockmark depressions, with regard to faunal distribution, abundance, and diversity, is demonstrated. Seston (including plank...