|Grazing by meso- and microzooplankton on phytoplankton in the upper reaches of the Schelde estuary (Belgium/The Netherlands)|Lionard, M.; Azémar, F.; Boulêtreau, S.; Muylaert, K.; Tackx, M.; Vyverman, W. (2005). Grazing by meso- and microzooplankton on phytoplankton in the upper reaches of the Schelde estuary (Belgium/The Netherlands). Est., Coast. and Shelf Sci. 64(4): 764-774. dx.doi.org/10.1016/j.ecss.2005.04.011
In: Estuarine, Coastal and Shelf Science. Academic Press: London; New York. ISSN 0272-7714, more
Grazing; Phytoplankton; World; Acanthocyclops robustus (Sars G.O., 1863) [WoRMS]; Brachionus Pallas, 1766 [WoRMS]; Calanoida [WoRMS]; Cladocera [WoRMS]; Copepoda [WoRMS]; Cyclopoida [WoRMS]; Cyclops vicinus Ulyanin, 1875 [WoRMS]; Daphnia O.F. Müller, 1785 [WoRMS]; Daphnia magna Straus, 1820 [WoRMS]; Eurytemora affinis (Poppe, 1880) [WoRMS]; Rotifera [WoRMS]; Synchaeta Ehrenberg, 1832 [WoRMS]; Eurasia [Marine Regions]; Europe [Marine Regions]; Brackish water; Fresh water
Schelde estuary; grazing; rotifers; mesozooplankton; phytoplankton; HPLC; CHEMTAX
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In contrast with the marine reaches of estuaries, few studies have dealt with zooplankton grazing on phytoplankton in the upper estuarine reaches, where freshwater zooplankton species tend to dominate the zooplankton community. In spring and early summer 2003, grazing by micro- and mesozooplankton on phytoplankton was investigated at three sites in the upper Schelde estuary. Grazing by mesozooplankton was evaluated by monitoring growth of phytoplankton in 200 µm filtered water in the presence or absence of mesozooplankton. In different experiments, the grazing impact was tested of the calanoïd copepod Eurytemora affinis, the cyclopoid copepods Acanthocyclops robustus and Cyclops vicinus and the cladocera Chydorus sphaericus, Moina affinis and Daphnia magna/pulex. No significant grazing impact of mesozooplankton in any experiment was found despite the fact that mesozooplankton densities used in the experiments (20 or 40 ind. l-1) were higher than densities in the field (0.1–6.9 ind. l-1). Grazing by microzooplankton was evaluated by comparing growth of phytoplankton in 30 and 200 µm filtered water. Microzooplankton in the 30–200 µm size range included mainly rotifers of the genera Brachionus, Trichocerca and Synchaeta, which were present from 191 to 1777 ind. l-1. Microzooplankton had a significant grazing impact in five out of six experiments. They had a community grazing rate of 0.41–1.83 day-1 and grazed up to 84% of initial phytoplankton standing stock per day. Rotifer clearance rates estimated from microzooplankton community grazing rates and rotifer abundances varied from 8.3 to 41.7 µl ind.-1 h-1. CHEMTAX analysis of accessory pigment data revealed a similar phytoplankton community composition after incubation with and without microzooplankton, indicating non-selective feeding by rotifers on phytoplankton.
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