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Seasonal development of cyanobacteria and microcystin production in Ugandan freshwater lakes
This study investigated the seasonal development of phytoplankton and potential microcystin (MC)‐producing cyanobacteria and MC concentrations in freshwater lakes in Uganda. During 1 year (May 2007–April 2008), monthly measurements were made of chemical and physical characteristics, phytoplankton composition and MC concentrations in a hypertrophic crater lake (Lake Saka), in shallow eutrophic lakes (Lakes Mburo, George and Edward) and in Lake Victoria (Murchison Bay, Napoleon Gulf). Throughout the study period, cyanobacteria (composed of the genera Anabaena, Aphanocapsa, Chroococcus, Cylindrospermopsis, Microcystis, Planktolyngbya and Planktothrix) dominated, always contributing >50% to the total phytoplankton biovolume. All samples from all sampling sites were found to contain MC. Samples from Lake Saka had the maximum MC concentration (10 μg L−1) in July 2007. The minimum concentration (0.02 μg L−1) was recorded in Lake George for the months of May and June 2007 and January and April, 2008. Intermediate MC concentrations (0.1–2.5 μg MC‐LR eq. L−1) were observed at all the sampling sites in the other three lakes. Highly significant positive linear relationships between the total MC concentration and Microcystis cell numbers were observed for all sampling sites. Relating the total MC concentrations to Microcystis cells revealed a >100‐fold variation in the average MC contents per cell between lakes. While Microcystis from Lake George exhibited the lowest MC cell quotas (0.03–1.24 fg cell−1), Microcystis from Lake Saka consistently exhibited maximum MC cell contents (14–144 fg cell−1). It was concluded that MC production was because of the occurrence of Microcystis at all sampling sites. The populations differed consistently between sites and independent of the season in their average MC content per cell.
Seasonal development of cyanobacteria and microcystin production in Ugandan freshwater lakes
This study investigated the seasonal development of phytoplankton and potential microcystin (MC)‐producing cyanobacteria and MC concentrations in freshwater lakes in Uganda. During 1 year (May 2007–April 2008), monthly measurements were made of chemical and physical characteristics, phytoplankton composition and MC concentrations in a hypertrophic crater lake (Lake Saka), in shallow eutrophic lakes (Lakes Mburo, George and Edward) and in Lake Victoria (Murchison Bay, Napoleon Gulf). Throughout the study period, cyanobacteria (composed of the genera Anabaena, Aphanocapsa, Chroococcus, Cylindrospermopsis, Microcystis, Planktolyngbya and Planktothrix) dominated, always contributing >50% to the total phytoplankton biovolume. All samples from all sampling sites were found to contain MC. Samples from Lake Saka had the maximum MC concentration (10 μg L−1) in July 2007. The minimum concentration (0.02 μg L−1) was recorded in Lake George for the months of May and June 2007 and January and April, 2008. Intermediate MC concentrations (0.1–2.5 μg MC‐LR eq. L−1) were observed at all the sampling sites in the other three lakes. Highly significant positive linear relationships between the total MC concentration and Microcystis cell numbers were observed for all sampling sites. Relating the total MC concentrations to Microcystis cells revealed a >100‐fold variation in the average MC contents per cell between lakes. While Microcystis from Lake George exhibited the lowest MC cell quotas (0.03–1.24 fg cell−1), Microcystis from Lake Saka consistently exhibited maximum MC cell contents (14–144 fg cell−1). It was concluded that MC production was because of the occurrence of Microcystis at all sampling sites. The populations differed consistently between sites and independent of the season in their average MC content per cell.
Seasonal development of cyanobacteria and microcystin production in Ugandan freshwater lakes
Okello, W. (author) / Kurmayer, R. (author)
Lakes & Reservoirs: Research & Management ; 16 ; 123-135
2011-06-01
13 pages
Article (Journal)
Electronic Resource
English
Seasonal development of cyanobacteria and microcystin production in Ugandan freshwater lakes
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