Effects of Nile Tilapia Fish Cage Farming on Macroinvertebrate Communities in Lake Kivu, Democratic Republic of the Congo

ABSTRACT This study analysed how macroinvertebrate communities in Lake Kivu responded to Nile tilapia cage farming. Macroinvertebrates were collected at two sampling stations impacted by fish farms and a control station without fish farming, and physicochemical variables were measured in situ. Water samples were analysed in the laboratory for nutrients and chlorophyll‐a. Only turbidity, water transparency, dissolved oxygen, and phosphate significantly differed between the three stations. Three macroinvertebrate phyla (Arthropoda, Mollusca, and Annelida), nine orders (Gastropoda, Diptera, Decapoda, Annelida, Odonata, Ephemeroptera, Coleoptera, Heteroptera, and Hemiptera), and 37 families were identified. Three groups, Diptera, Gastropoda, and Odonata, were abundant and dominated both cage and control stations. Predators, collector‐gatherers, and scavengers were more dominant than scrapers and shredders. The composition of macroinvertebrate communities significantly differed between the three stations, but not between the fish cage and control stations. Moreover, there were no significant seasonal differences in community composition. Accordingly, cage farming does not yet seem to pose a threat to Lake Kivu's ecological condition. Nonetheless, we recommend frequent monitoring of water and sediment quality to detect early signals and avoid fish farms impacting the ecosystem health of the lake.