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Seston and dissolved organic carbon dynamics during Microcystis bloom with special reference to the effects of three Chinese domestic fishes in experimental enclosures

Xue-jun, Liu, Ping, Xie
Chinese journal of oceanology and limnology 1997 v.15 no.3 pp. 216-223
Ctenopharyngodon idella, metabolism, stocking rate, lakes, carp, Hypophthalmichthys nobilis, dissolved organic carbon, statistical analysis, ecosystems, chlorophyll
The Microcystis bloom that once disappeared from Donghu Lake, a shallow, eutrophic Chinese lake, was successfully resumed with the use of the enclosure method. Seston and dissolved organic carbon (DOC) dynamics during the Microcystis bloom were investigated with particular emphasis on the effect of three Chinese domestic fishes (silver carp, bighead carp and grass carp). The results showed that the change of chlorophyll a obviously related to the fish species and its stocking density. Due to the release of extracellular ogranic carbon and increased bacterial activity, DOC increased apparently after silver and bighead carps were introduced. POC/DOC dropped considerably in the enclosures containing silver and bighead carps and in the surrounding lake water, which implied that the bacterial activity was more pronounced in such ecosystems. Statistical analysis indicated that the linear relationship between POC and chlorophyll a could reflect the state of algal growth and nutrient metabolism. It was expected that this study would provide some information on biomanipulation in the shallow, eutrophic lakes.