PLANKTON AND MACROINVERTEBRATE COMMUNITY COMPOSITION IN THE PELAGIC AND NON-VEGETATED LITTORAL DRAWDOWN ZONES OF A SHALLOW RESERVOIR, MANJIRENJI, ZIMBABWE

We examined the influence of physicochemical variables on zooplankton, phytoplankton and macroinvertebrate community composition in a shallow dam, Manjirenji in Zimbabwe. And further explored the relations between selected water parameters on chlorophyll a production as a proxy for phytoplankton biomass in the non-vegetated littoral drawdown zone in comparison to the pelagic zone. We observed high similarity overlaps between some water parameters, and a uniform dominance pattern of zooplankton comprising of rotifers > copepods > cladocera in littoral and pelagic sites, though the dominance order for phytoplankton varied significantly between lake zones. Pollution sensitive macroinvertebrate families dominated in the non-littoral vegetated drawdown zone. Physicochemical variables account for low plankton (50.37%) and macroinvertebrates (59.59%) ecogeography suggesting the influence of latent (unexplored) environmental and biotic factors on plankton and macroinvertebrate community composition in this lake. There was no significant predictor factor among Secchi depth, total nitrogen, and total phosphorus towards chlorophyll a production in the Dam. Non-vegetation in littoral drawdown zones of the shallow turbid lake reduce habitat complexity conferring functional and structural similarity with the pelagic zone. There is a need to comprehend transitional nutrient and water hydrodynamics and their effects on aquatic biodiversity in shallow lakes.