Diversity and ecology of phytoplankton in Lake Edward (East Africa): Present status and long-term changes

Maya P. Stoyneva-Gärtner, Cédric Morana, Alberto V. Borges, William Okello, Steven Bouillon, Loris Deirmendjian, Thibault Lambert, Fleur Roland, Angela Nankabirwa, Erina Nabafu, François Darchambeau, Jean Pierre Descy

Research output: Contribution to journalArticlepeer-review


Lake Edward is one of the African Rift Valley lakes draining into the Nile River basin. We conducted three sampling series in Lake Edward in October-November 2016, March-April 2017 and January 2018, in distinct seasonal conditions and in several sites varying by depth and proximity to river outlets, including the Kazinga Channel, which connects the hypertrophic Lake George to Lake Edward. The phytoplankton was examined using microscopy and marker pigment analysis by high performance liquid chromatography (HPLC) and subsequent CHEMTAX processing for estimating abundance of phytoplankton groups. Chlorophyll a concentration in the pelagic and littoral open lake sites barely exceeded 10 µg L−1 whereas, in contrast, in the semi-enclosed Bay of Katwe influenced by the Kazinga Channel chlorophyll a was up to 100 µg L−1. Despite substantial seasonal variations of limnological conditions such as photic and mixed layer depths, cyanoprokaryotes/cyanobacteria represented on average 60% of the phytoplankton biomass, followed by diatoms, which contributed ~25% of chlorophyll a, and by green algae, chrysophytes and cryptophytes. 248 taxa were identified with clear prevalence of cyanobacteria (104 taxa), from the morphological groups of coccal and filamentous species (non-heterocytous and heterocytous). The high proportion of heterocytous cyanobacteria, along with a relatively high particulate organic carbon to nitrogen (C:N) ratio, suggest N limitation as well as light limitation, most pronounced in the pelagic sites. During the rainy season, the most abundant diatoms in the plankton were needle-like Nitzschia. Comparison with previous studies found differences in water transparency, total phosphorus, and phytoplankton composition.

Original languageEnglish
Pages (from-to)741-751
Number of pages11
JournalJournal of Great Lakes Research
Issue number4
Publication statusPublished - Aug 2020
Externally publishedYes


  • Biodiversity
  • Community structure
  • Long-term change
  • Productivity
  • Tropical lake


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