Invloed van de bioturbator Corophium volutator op de opname van diatomeeën door harpacticoïde copepoden
Legrand, C. (2007). Invloed van de bioturbator Corophium volutator op de opname van diatomeeën door harpacticoïde copepoden. MSc Thesis. Universiteit Gent. Faculteit Wetenschappen: Ghent. 69 + 1 appendix pp.
The amphipod Corophium volutator is abundant in the intertidal mudflats of the Ijzerestuarium (Nieuwpoort). There are indications that bioturbation in soft bottoms plays a majorrole in marine and fresh water systems by changing the physical, chemical and biologicalproperties of the sediment. Corophium volutator consumes diatoms and can, when present inhigh densities, regulate the abundance and species composition of the diatom community.There are indications for macro- meiofauna interactions and competition with other depositfeeders can be expected when food is a limiting factor. The effect of bioturbation by C.volutator on the functionality of the co-occuring copepod species Platychelipus littoralis wasstudied in this thesis. The effect of the amphipod on the production of extracellukar polysacharids (EPS) by epipelic diatoms and the stability of the sediment was also studied. For this purpose, several experiments were conducted. First the feeding rate of C. volutator was studied in the absence and presence of sediment. EPS production was also measured in the absence and presence of C. volutator. In another experiment, the effect of C. volutator on the feeding rate of Platychelipus littoralis was tested by means of 13C labeled diatoms. Thisexperiment was first conducted in petri dishes but was later repeated in sediment cores. At the end of each experiment, EPS production was measured. The stability of the sediment in the cores was measured using a Cohesive Strength Meter (CSM). The presence of C. volutator had no effect on the production of EPS by the diatom Navicula phyllepta. The harpacticoid Platychelipus littoralis showed an increase in uptake in thepresence of the amphipod. This is probably due to a better mixing of the diatom biofilm down to deeper sediment layers by C. volutator. This can increase the food availability for the benthic harpacticoid P. littoralis. Bioturbation by C. volutator caused a decrease in erosion treshold of the sediment. This is probably due to an increase in pore spaces and saturation on emersion, by retention of water by the secretions that line their burrows. The grazing upon diatoms that stabilize the sediment through their biofilm, will also have a negative effect on the overall sediment stability. Corophium volutator is not only responsable for bioturbation of the sediment but also causes functional changes that will affect co-occuring species. The dominant harpacticoid P. littoralis in our study area was positively affected. This contributes to an optimum use of the available primary production.
Dataset
Influence of the bioturbator Corophium volutator on the uptake of diatoms by harpacticoid copepods, more
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