Collected reprints: Abstract 3514
Collected reprints
Abstract
Bakker, C.; De Pauw, N. (1975). Comparison of plankton assemblages of identical salinity ranges in estuarine tidal, and stagnant environments : 2. Zooplankton. Neth. J. of Sea Res. 9(2): 145-165
A comparison was made between the zooplankton assemblages of the meso-and polyhaline ranges of the Westerschelde estuary and Lake Veere (SW Netherlands). Species composition and density of the zooplankton of brackish water ecosystems depend not only on salinity but on several other factors too. Zooplankton development in stagnant Lake Veere and tidal Westerschelde waters of the same salinity is quite different. Important factors appeared to be food supply, water movement and water exchange.
Lake Veere zooplankton subsists on a diversified and dense phytoplankton as source of food during long periods of the year. Continuous turbulent water movement is absent. The combination of these factors is favourable for rotifers and polychaet larvae. Several groups, i.e. protozoans, rotifers, larvae of olychaets and molluscs, copepods, constitute important parts of total average biomass. Westerschelde zooplankton in the mesohaline area of the estuary subsists on detritus as the only important source of food throughout the year. Phytoplankton is densest in summer but small species, essential as food, are quantitatively rare. Strong tidal turbulence tends to disperse the organisms in the whole water mass. Tidal exchange causes transport of organisms in seaward direction. These conditions are unfavourable especially for rotifers. Copepods show successful adaptation to the estuarine environment. Average standing stocks in the mesohaline area are much larger than in Lake Veere.
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