Ecological water quality and benthic macroinverte-brates: impact on fish spawning grounds in Lake Buyo, Côte d’Ivoire

Abstract

This study aimed to determine the ecological quality of ichthyological spawning grounds in the Lake Buyo partial wildlife reserve, part of Taï National Park. Ichthyological spawning grounds are aquatic habitats used by fish for reproduction. In Côte d’Ivoire, knowledge of these spawning grounds was very fragmentary and mostly based on an inventory and summary description of spawning grounds. Data collection was carried out from June 2018 to May 2019 at 11 ichthyological spawning grounds. Benthic macroin-vertebrates were sampled using a Van Veen bucket and handle dip net. Ten grab samples were taken at each site. The dip net was used to sample habitats that were difficult to access with the grab and were very shallow. The Warwick Ecological Stress Index and the Hilsenhoff Biotic Index were used to analyse water quality. A total of 19,940 individuals belonging to 28 families for a biomass of 1,361,549 g were counted. Thiaridae and Chironomidae families were the most abundant, with 63.28% and 22.88%, respectively. The analysis of the abundance– biomass curves showed that the biomass curve was higher than the abundance curve, with values ranging from 0.18 to 0.61. These values indicate stress due to the enrichment of the water with organic matter. The analysis using the Hilsenhoff Biotic Index indicated that organic pollution ranges from poor (6.98) to very poor (7.73). The ecological quality of the lake’s waters has a negative impact on ecological diversity, leading to the disappearance of certain aquatic species through the destruction of spawning grounds.