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The role of the benthic biota in sedimentary metabolism and sediment-water exchange processes in the Goban Spur area (NE Atlantic)

Heip, C.H.R. and Duineveld, G. and Flach, E. and Graf, G. and Helder, W. and Herman, P.M.J. and Lavaleye, M. and Middelburg, J.J. and Pfannkuche, O. and Soetaert, K.E.R. and Soltwedel, T. and De Stigter, H. and Thomsen, L. and Van Averbeke, J. and De Wilde, P. (2001) The role of the benthic biota in sedimentary metabolism and sediment-water exchange processes in the Goban Spur area (NE Atlantic). Deep-Sea Research Part II-Topical Studies in Oceanography, 48, 3223-3243. ISSN 0967-0645.

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Official URL: http://dx.doi.org/10.1016/S0967-0645(01)00038-8

Abstract

We provide an overview of the role of biological processes in the Benthic boundary layer (BBL) and in sediments on the cycling of particulate organic material in the Goban Spur area (Northeast Atlantic). The benthic fauna, sediment and BBL characteristics were studied along a transect ranging from 208 to 4460m water depth in different seasons over 3 years. Near- bottom flow velocities are high at the upper part of the slope (1000-1500m), and high numbers of filter-feeding taxa are found there such that organic carbon normally passing this area during high flow conditions is probably trapped, accumulated, and/or remineralised by the fauna. Overall metabolism in shelf and upper slope sediments is dominated by the macrofauna. More than half of the organic matter flux is respired by macrofauna, with a lower contribution of metazoan meiofauna (4%) and anoxic and suboxic bacterial mineralisation (21%); the remainder (23%) being channelled through nanobiota and oxic bacteria. By its feeding activity and movement, the macrofauna intensely reworks the sediments on the shelf and upper slope. Mixing intensity of bulk sediment and of organic matter are of comparable magnitude. The benthos of the lower slope and abyssal depth is dominated by the microbiota, both in terms of total biomass (> 90%) and carbon respiration (about 80%). The macrofauna (16%), meiofauna (4%) and megafauna (0.5%) only marginally contribute to total carbon respiration at depths below 1400m. Because large animals have a lower share in total metabolism, mixing of organic matter within the sediments is reduced by a factor of 5, whereas mixing of bulk sediment is one to two orders of magnitude lower than on the shelf. The food quality of organic matter in the sediments in the shallowest part of the Goban Spur transect is significantly higher than in sediments in the deeper parts. The residence time of mineralisable carbon is about 120 d on the shelf and compares well with the residence time of the biota. In the deepest station, the mean residence time of mineralisable carbon is more than 3000 d, an order of magnitude higher than that of biotic biomass. [KEYWORDS: European continental-margin; deep-sea sediments; northeast atlantic; boundary-layer; seasonal-variations; particulate matter; organic-carbon; slope; transport; respiration]

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:11013
Deposited On:24 Nov 2011 01:00
Last Modified:31 Mar 2014 10:32

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