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Oxygen as a control on sea floor biological communities and their roles in sedimentary carbon cycling

Woulds, C. and Cowie, G.L. and Levin, L.A. and Andersson, J.H. and Middelburg, J.J. and Vandewiele, S.L. and Lamont, P.A. and Larkin, K.E. and Gooday, A.J. and Schumacher, S. and Whitcraft, C. and Jeffreys, R.M. and Schwartz, M. (2007) Oxygen as a control on sea floor biological communities and their roles in sedimentary carbon cycling. Limnology and Oceanography, 52, 1698-1709. ISSN 0024-3590.

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13C tracer experiments were conducted at sites spanning the steep oxygen, organic matter, and biological community gradients across the Arabian Sea oxygen minimum zone, in order to quantify the role that benthic fauna play in the short-term processing of organic matter (OM) and to determine how this varies among different environments. Metazoan macrofauna and macrofauna-sized foraminiferans took up as much as 56 ± 13 mg of added C m-2 (685 mg C m-2 added) over 2–5 d, and at some sites this uptake was similar in magnitude to bacterial uptake and/or total respiration. Bottom-water dissolved oxygen concentrations exerted a strong control over metazoan macrofaunal OM processing. At oxygen concentrations <7 µmol L-1 (0.16 ml L-1), metazoan macrofauna were able to take advantage of abundant OM and to dominate OM uptake, while OM processing at O2 concentrations of 5.0 µmol L-1 (0.11 ml L-1) was dominated instead by (macrofaunal) foraminiferans. This led us to propose the hypothesis that oxygen controls the relative dominance of metazoan macrofauna and foraminifera in a threshold manner, with the threshold lying between 5 and 7 µmol L-1 (0.11 to 0.16 ml L-1). Large metazoan macrofaunal biomass and high natural concentrations of OM were also associated with rapid processing of fresh OM by the benthic community. Where they were present, the polychaete Linopherus sp. and the calcareous foraminiferan Uvigerina ex gr. semiornata, dominated the uptake of OM above and below, respectively, the proposed threshold concentrations of bottom-water oxygen.

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:4535
Deposited On:16 Sep 2009 02:00
Last Modified:15 Jan 2014 09:21

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