Abstract
The seasonal development of the phytoplankton, phytobenthos, zooplankton, and microbenthos in a high eutrophised intravilan water reservoir was studied. Finally, 25 genera with 44 species of Cyanobacteria/Cyanophytes and 67 genera with 102 species as well as infraspecific taxa of different groups of microscopic algae were identified. The phytoplankton in most parts of the water basin was strongly dominated by green colonial alga Golenkiniopsis longispina. From October until December a cyanophyte species Aphanocapsa delicatissima with typical cell dimensions of picoplankton/ was found in large amounts/predominated. As early as spring, a plankton bloom in all its components was observed. At that time, also a high concentration of total phosphorus was recorded, which in the second half of April dropped rapidly. The concentration of chlorophyll-a increased from 162.7 μg/L in March to 2322 μg/L in September. Massive occurrence of benthic protozoa in the plankton, as a consequence of anoxia, has been observed. Further, the detritivore and omnivore ciliate species Coleps hirtus dominated in the microbenthos. Altogether 74 of ciliate taxa were detected. Their abundance and biomass reached peak in April, but these steadily decreased from May until the end of the year. Extreme values of zooplankton density (54,016 ind/L) were recorded in spring followed by a sudden fall in summer and autumn. The contribution of rotifers (Brachionus spp., Filinia longiseta) in the total zooplankton density and biomass was 98%. Relatively a low species richness of crustaceans (4 Cladocera and 3 Copepoda) was observed.
Highlights
Cultural eutrophication is the Earth’s most widespread water quality problem
In this paper we describe the seasonal development of phytoplankton, algal picoplankton, cyanobacterial bloom, ciliates and metazooplankton in small hypertrophic urban reservoir in 2009 and try to elucidate some interactions between food web components
There are some evidence about the high eutrophication of water body in the reservoir: 1) cyanobacterial bloom and high chlorophyll-a content as a consequence of a high phosphorus content; 2) changes in species composition of planktonic communities, decrease of quantity and species biodiversity at all plankton communities and microbenthos; 3) anoxia at the bottom of reservoir indicated by protozoan community
Summary
Cultural eutrophication is the Earth’s most widespread water quality problem. It causes harmful algal blooms, fish kills and many related problems in fresh waters that are adjacent to areas with large human populations [1].The small size and shallow water bodies are less stable than larger lakes, and very sensitive to any human intervention. Cultural eutrophication is the Earth’s most widespread water quality problem. It causes harmful algal blooms, fish kills and many related problems in fresh waters that are adjacent to areas with large human populations [1]. The biological reaction of aquatic system to nutrient enrichment is the eutrophication, the eventual conesquence of which is the development of primary production to nuisance proportions [4]. Eutrophication causes considerable changes in biochemical cycles and biological communities [8]. Community interaction in pelagic food webs is affected by large scale of physical, chemical and biological processes and are govern by nutrient limitation, competition, predation and other ecological forces [9,10]. Trophic level interactions are complicated by detritus pathways and influences from the sediments [11]
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