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The macro- and micro-scale patchiness of meiobenthos associated with the Darwin Mounds (north-east Atlantic)

Published online by Cambridge University Press:  24 May 2004

S. Van Gaever
Affiliation:
University of Gent, Section Marine Biology, Krijgslaan 281-S8, B-9000 Gent, Belgium
A. Vanreusel
Affiliation:
University of Gent, Section Marine Biology, Krijgslaan 281-S8, B-9000 Gent, Belgium
J.A. Hughes
Affiliation:
DEEPSEAS Group, George Deacon Division, Southampton Oceanography Centre, Empress Dock, Southampton, SO14 3ZH, UK
B.J. Bett
Affiliation:
DEEPSEAS Group, George Deacon Division, Southampton Oceanography Centre, Empress Dock, Southampton, SO14 3ZH, UK
K. Kiriakoulakis
Affiliation:
University of Liverpool, Department of Earth and Ocean Sciences, Liverpool, L69 3GP, UK

Abstract

Meiobenthic community structure was investigated at different spatial scales (from 100 metres to centimetres) on and adjacent to a group of coral-topped sandy mounds in the bathyal north-east Atlantic (Darwin Mounds, Rockall Trough) and related to the environmental conditions in the area, mainly differences in sediment organic carbon content and presence of biogenic structures. Meiobenthos abundances were similar to those observed in other deep-sea sites, with nematodes representing at least 94% of the total community. The dominant nematode genera were Microlaimus, followed by Sabatieria, Richtersia, Rhynchonema and Trefusia, together with typical deep-sea genera (e.g. Halalaimus and Acantholaimus). Multivariate analysis of nematode generic relative abundances at the different stations indicated that there was no significant influence on distribution resulting from large scale topographic and biogeochemical conditions around the mounds. The same genera were associated with dead tests of the xenophyophore Syringammina fragilissima and in the surrounding sediments. The vertical distribution of nematodes on and adjacent to the mound showed some unusual features, as the deeper layers of the sediments were inhabited by stilbonematids. These genera harbour ectosymbiotic, chemoautotrophic bacteria and have not previously been recorded from the deep sea. The occurrence of stilbonematids in notable numbers in the subsurface layers of the sediments in the vicinity of the Darwin Mounds provides evidence for the occurrence of anoxic microenvironments.

Type
Research Article
Copyright
2004 Marine Biological Association of the United Kingdom

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