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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 1852

Karl E. Havens III and John De Costa; Freshwater plankton community succession during experimental acidification. Arch.Hydrobiol. 111(1):37-65, 1987

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Lakewater inside 2 m3 bags, suspended in Lake O'Woods, West Virginia, was acidified from pH 7.2 to pH 6.5 or 4.5 via incremental H2SO4 additions, which reduced pH by 0.5 units per week to the desired levels. Two bags were untreated controls. Algal and zooplankton species richness declined with increasing acidity. While diatoms and unicellular greens were the dominant control algae, the filamentous green Mougoetia viridis and the dinoflagellate Peridinium incomspicuum became dominant in all acidified bags. Total algal biomass, measured as chlorophyll-a, increased significantly with acidification, especially at pH 4.5. Total zooplankton abundance increased with acidification to pH 6, where edible algal biomass was high, and decreased in pH 5 and 4.5 bags, where M. viridis and P. inconspicuum accounted for ca. 99% of the total biomass. Copepod abundance declined when pH dropped below 5.5, and at pH 4.5, two small cladocerans, Bosmina longirostris and Chydorus sphaericus, became the dominant crustaceans. Only one rotifer, Lecane luna, persisted at pH 4.5. Overall, the plankton community in the pH 4.5 bags closely resembled that in nearby acid lakes.