Density, vertical distribution and trophic responses of metazoan meiobenthos to phytoplankton deposition in contrasting sediment types

We investigated meiobenthic community response (as density and vertical distribution) to the sedimentation of phytoplankton in 2 contrasting sites in the southern North Sea, one with fine grained sediment close to the coastline and another with highly permeable sediments. Meiobenthic densities and p...

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Bibliographic Details
Published in:Marine ecology. Progress series (Halstenbek) 2008-04, Vol.358, p.51-62
Main Authors: Franco, M. A., Soetaert, K., Van Oevelen, D., Van Gansbeke, D., Costa, M. J., Vincx, M., Vanaverbeke, J.
Format: Article
Language:English
Subjects:
Carbon isotopes
Copepoda
Marine
Metazoa
Nematoda
Nematodes
Nitrogen isotopes
Phytoplankton
Richtersia
Sabatieria
Seas
Sediment deposition
Sediments
Signatures
Taxa
Vertical distribution
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Summary:We investigated meiobenthic community response (as density and vertical distribution) to the sedimentation of phytoplankton in 2 contrasting sites in the southern North Sea, one with fine grained sediment close to the coastline and another with highly permeable sediments. Meiobenthic densities and pigments in the water column and sediment were measured monthly from October 2002 until October 2003. Stable isotope13C and15N signatures were analysed in sediment particulate organic matter (POM), water suspended particulate matter (SPM) and in different meiobenthic taxa at 3 different times (prior, during and after spring bloom deposition) at 2 sediment depths (0 to 1 and 4 to 5 cm). Our aim was to determine whether sediment type affects the overall meiobenthic community response (densities and vertical distribution) and utilisation of freshly deposited phytoplankton as a food source. Variation in nematode response to the sedimentation event was evident and was related to the contrasting biogeochemical processes at the stations. In permeable sediments, the nematode response was rapid after phytoplankton deposition, while in the fine-grained station, nematode response (as density) was delayed. In general, meiobenthic13C signatures remained relatively constant over time and were not coupled with changes in water SPM and sediment POM. There was vertical variation in meiobenthic13C signatures in fine sediments. Nematodes belonging to the generaSabatieriaandRichtersiafrom the deeper sediment layer had isotope signatures similar to those of surface living nematodes, indicating migration of these genera to the surface to feed. In permeable sediments, such vertical differences were absent because of sediment biogeochemical properties. δ13C and δ15N values of copepods clearly indicated a chemoautotrophic food source within the fine-grained sediment, which has not been previously reported for these environments.
ISSN:0171-8630
1616-1599
DOI:10.3354/meps07361