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Does sediment grain size affect diatom grazing by harpacticoid copepods?
Marleen De Troch1, Lieven Houthoofd, Victor Chepurnov
1Ghent University, Biology Department, Marine Biology Section, Campus Sterre, B-9000 Gent, Belgium. marleen.detroch@ugent.be
Marine Environmental Research
|December 14, 2005
Summary
Sediment grain size significantly impacts harpacticoid copepod grazing on diatoms. Fine silts inhibit feeding, while coarser sands and no sediment enhance it, affecting estuarine food webs.
Area of Science:
- Marine Ecology
- Benthic Ecology
- Estuarine Biology
Background:
- Estuarine soft sediments host diverse organisms, but the sediment's role in their function is unclear.
- Harpacticoid copepods are key grazers in these environments, influencing primary producer communities.
Purpose of the Study:
- To investigate the effect of sediment grain size on harpacticoid copepod grazing behavior.
- To understand how different sediment types influence the feeding efficiency of two intertidal harpacticoid species.
Main Methods:
- Controlled experiments using two harpacticoid copepod species (Paramphiascella fulvofasciata, Nitokra spinipes) and two diatom species (Navicula phyllepta, Seminavis robusta).
- Testing grazing activity across various sediment grain sizes, including fine silt, coarse sands, glass beads, and no sediment.
- Utilizing 13C-enriched diatoms for tracing uptake in copepods.
Main Results:
- Harpacticoid copepods exhibited the highest diatom uptake in the absence of sediment.
- No diatom uptake was observed in silty sediment conditions (<63 microm).
- Grazing activity generally increased with increasing mean sediment grain size.
Conclusions:
- Fine sediment grains negatively impact copepod grazing efficiency by altering biofilm structure and grazer mobility.
- These findings highlight the sensitivity of grazer-producer dynamics to sediment characteristics.
- Results suggest potential implications for tidal flat ecosystems affected by siltation from human activities.