Relationship between Diatoms and Zooplankton Distribution in Lake Dogodogo Located in Bujumbura Province, Burundi

Abstract

Lake Dogodogo supports diverse plankton communities that contribute to aquatic food-web processes. This study assessed the influence of planktonic diatoms on zooplankton distribution to inform sustainable management of the lake’s fishery resources. Sampling was conducted twice monthly from May to August 2022 at seven stations representing littoral and pelagic conditions. Zooplankton and diatoms were collected with a 50 µm plankton net by five successive immersions per station to form a composite sample, which was fixed with 5% formalin. Species were identified microscopically, abundances were determined, diversity indices were calculated, and differences among stations were evaluated using ANOVA. Redundancy analysis was used to examine relationships between diatoms and zooplankton. In total, 33 zooplankton species belonging to rotifers, copepods and cladocerans and 17 diatom species were recorded. Polyarthra vulgaris was the most abundant zooplankton species, whereas Epithemia cistula was dominant among diatoms. Several zooplankton taxa varied significantly among stations, while planktonic diatoms did not show significant spatial variation. Zooplankton was generally more diverse and abundant than diatoms. Redundancy analysis indicated that Gomphonema parvulum and Gomphonema truncatum significantly influenced zooplankton distribution. The observed decline in diatom abundance during periods of greater zooplankton abundance was consistent with grazing pressure. These findings show that Lake Dogodogo contains substantial plankton biodiversity and that diatom–zooplankton relationships are relevant to understanding its ecological functioning and conservation.