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Does sediment grain size affect diatom grazing by harpacticoid copepods?
De Troch, M.; Houthoofd, L.; Chepurnov, V.; Vanreusel, A. (2006). Does sediment grain size affect diatom grazing by harpacticoid copepods? Mar. Environ. Res. 61(3): 265-277. dx.doi.org/10.1016/j.marenvres.2005.10.004
In: Marine Environmental Research. Applied Science Publishers: Barking. ISSN 0141-1136; e-ISSN 1879-0291
Peer reviewed article  
Available in  Authors 
  • Vlaams Instituut voor de Zee: Open Marine Archive 114294 [ download pdf ]
  • Waterbouwkundig Laboratorium: Overdrukjes 114297 [114357] [ request ]
Keywords
    Algae > Diatoms
    Behaviour > Feeding behaviour > Grazing
    Dimensions > Size > Grain size
    Sediments
    Bacillariophyceae [WoRMS]; Copepoda [WoRMS]; Navicula phyllepta Kützing, 1844 [WoRMS]; Nitokra spinipes Boeck, 1865 [WoRMS]; Paramphiascella fulvofasciata Rosenfield & Coull, 1974 [WoRMS]; Seminavis robusta D.B.Danielidis & D.G.Mann, 2002 [WoRMS]
    PaulinaSchor [Marine Regions]
    Marine/Coastal
Author keywords
    copepoda; diatoms; grazing; sediment
Authors  Top 
  • De Troch, M.
  • Houthoofd, L.
  • Chepurnov, V.
  • Vanreusel, A.
Abstract
    Estuarine soft sediments support a diverse group of eukaryotic and prokaryotic organisms though the role of the sediment per se for the functioning of these organisms remains largely unknown. The present study aimed to test the effect of sediment grain size on the grazing activities of harpacticoid copepods. In controlled experiments, two common intertidal harpacticoid species (Paramphiascella fulvofasciata and Nitokra spinipes) were each offered a mix of two benthic diatom species (Navicula phyllepta and Seminavis robusta) in different sedimentary conditions. Several microcosms were created using a variety of sediment types, including fine silt (<63 µm), coarser grained sands (125-250, 250-450, 100-300 µm), artificial ‘sediments’ of glass beads (250-500, 2000 µm) and even the absence of sediment was tested. The diatoms were enriched in the stable carbon 13C to facilitate tracing in the harpacticoids. Both copepod species were able to graze on the diatoms with highest uptake when sediment was absent. In contrast, both harpacticoid species showed no uptake in silty conditions. In general, grazing was favoured when mean sediment grain size increased. The strong negative effect of fine grains on the grazer’s efficiency can be explained by the resulting differences in the structure (and accessibility) of the diatom biofilm on the one hand and the mobility of the grazer on the other hand. In view of the subtle equilibrium between primary producers and grazers, these results might have important implications for the effect of siltation of tidal flats due to, e.g., human activities.
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