Influence of Environmental Variables on Fish Distribution in the Flooded Swamp Forest of the Lake Tumba Micro-basin on the Mbandaka- Research Center in Ecology and Forestry of Mabali (CREF Mabali) Road Axis in Bikoro, Equateur Province (DR Congo)

Abstract

Background and Objective: The majority of aquatic ecosystems in the Democratic Republic of Congo are highly anthropized, which could negatively influence biodiversity. The overall objective of this study is to evaluate the influence of environmental variables on fish distribution in the flooded swamp forest of the Lake Tumba micro-basin on the Mbandaka- Research Center in Ecology and Forestry of Mabali road. Study Area: This study took place in ponds, swamps, marigots and small streams in relation to Lake Tumba in the flooded forest zone of the Mbandaka-Mabali road axis in the territory of Bikoro, Equateur Province in the Democratic Republic of Congo. Methods: Fish were collected using different fishing techniques and gears. Physico-chemical parameters were sampled using a multi-parameter Combo pH probe of the brand Hanna pH/ORP/EC/DO N° HI 9828, dissolved oxygen was measured using the Brand Voltcraft DO-100 oximeter and depth was determined using a graduated board. Several ecological indices of fish communities were determined as well as Hierarchical Ascending and Principal Component Classification analyses. Results: Twenty-two fish species belonging to ten orders, thirteen families and fifteen genera were identified. The average values of the abiotic variables show that the waters of the study area are characterized by low values of physico-chemical parameters within the ranges compatible with the survival of the local fish fauna. The canonical correspondence analyses reveal that five environmental variables (temperature, depth, dissolved oxygen, sandy bottom and sandy-muddy or gravelly bottom) would explain the abundance and distribution of fourteen fish species in the Longonye site. In contrast, turbidity, conductivity, pH, muddy bottom, and bottom littered with plant debris influenced the abundance and distribution of eight fish species at the Hongo, Ilungu, Lotende and Membe sites. Scoop fishing, stump removal, and the use of ichthyotoxic plants were the main anthropogenic activities that could compromise the fish fauna in the study area. Conclusion and Outlook: Promoting sustainable local fishing methods would help preserve the fish fauna studied and limit the deterioration of fish habitats.