Seasonal variation in the diversity and species richness of phytoplankton in a tropical eutrophic reservoir |
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Authors: | Figueredo Cleber C Giani Alessandra |
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Institution: | (1) Department of Systematic Biology, National Museum of Natural History, Smithsonian Institution, Washington, DC, 20560-0163, U.S.A.;(2) Department of Biology, George Washington University, Washington, DC, 20052, U.S.A. |
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Abstract: | The water chemistry, structure of sediment grain size, algal biomass, and patterns of nine bacteria physiological groups were studied monthly from May to October 1991 in an adjacent stream, ecotone, and reservoir zones (southern Poland). The distribution of five particulate organic carbon fractions was significantly different among the zones. Biomass of benthic algae demonstrated a maximum in the ecotone (22.74 g C m–2). Most of the bacterial groups were more numerous in the stream sediments where aerobic heterotrophs prevailed (1.2–6.5 × 1011 cells m–2). The significant differences in density were found for anaerobic heterotrophs, anaerobic nitrogen fixing, amylolytic, and cellulolytic bacteria among the zones. The small density of bacteria in the ecotone was probably an effect of the rapid water fluctuations, accompanied by movement of fine sediments or/and an inhibitory effect of compounds secreted by the periphyton. The principal component analysis showed that the ecotone zone was more similar to the reservoir open water than to the stream. |
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Keywords: | Nemertea Heteronemertea phylogeny morphology |
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