Impact des pratiques agricoles sur les macros invertébrées benthiques de la rivière Nyabarongo (bassin du lac Kivu, RDC)[Impact of Agricultural Practices on Benthic Macroinvertebrates in the Nyabarongo River, Lake Kivu Basin, Democratic Republic of the Congo]

This study examines the effects of agricultural practices on aquatic biodiversity in the Nyabarongo River, an important tributary of Lake Kivu in the Democratic Republic of the Congo. It addresses the growing degradation of freshwater ecosystems associated with the expansion of farming activities in the watershed. The main pressures identified include soil erosion, uncontrolled use of fertilizers and pesticides, and the destruction of riparian vegetation, all of which contribute to declining water quality and ecological imbalance. The study focuses on benthic macroinvertebrates because they are reliable indicators of aquatic ecosystem health. Its objectives are to identify the dominant agricultural practices in the watershed, assess the diversity and abundance of macroinvertebrates at sites exposed to different levels of agricultural pressure, compare biological indicators between intensively cultivated and less disturbed areas, and examine the relationship between physicochemical water parameters and macroinvertebrate community structure. The research combines biological, chemical, and social approaches. Macroinvertebrates were collected and identified at several points along the river, while water samples were analyzed for pH, temperature, turbidity, nitrates, and phosphates. Surveys conducted among local farmers provided additional information on land-use patterns, cultivation methods, and the use of agricultural inputs. The results show a strong relationship between intensive farming and the decline of aquatic biodiversity. Heavily cultivated sites had lower species richness and abundance, poorer water quality, and a higher proportion of pollution-tolerant organisms. Sensitive taxa belonging to Ephemeroptera, Plecoptera, and Trichoptera declined as agricultural pressure increased, whereas tolerant groups, particularly Diptera, became more dominant. High turbidity and elevated nutrient concentrations were also associated with changes in community composition. The study concludes that unsustainable agricultural land use is a major cause of ecological degradation in the Nyabarongo River. It recommends the adoption of agroecological practices, reduced use of chemical inputs, erosion control, restoration of vegetated riparian buffers, and regular monitoring of water quality through aquatic bioindicators. These measures could help protect freshwater biodiversity while maintaining agricultural production. The findings provide a scientific basis for local authorities, farmers, and environmental organizations to develop more sustainable watershed management strategies and to reconcile rural development with the conservation of the Lake Kivu basin. More broadly, the research highlights the need for integrated management involving communities, public institutions, and agricultural stakeholders. Farmer training, environmental awareness, and participatory monitoring are essential to reduce pollution sources, restore river functions, and preserve ecosystem services on which surrounding populations depend for livelihoods, food security, and long-term resilience.