Ichthyofauna Structure and Multimetric Fish Index to Assess the Biotic Integrity of Hana River in Tai National Park (Côte d’Ivoire)

The Hana River, a tributary of the Cavally River, is the main stream that crosses Tai National Park from northeast to southwest. This park, located in the south-west of the Ivory Coast, is the largest primary tropical rainforest in West Africa and known to be a biodiversity hotspot. However, anthropogenic activities around the park could disturb the Hana River. The purpose of this study is to assess the water quality of this river from the analysis of the structure of the fish population. Three stations were sampled in the dry season using a battery of 10 gillnets (8 - 40 mm mesh) placed between 5 p.m. and 7 a.m. and 7 a.m. and 12 p.m. The Hana River Biotic Integrity Index is based on the ten metrics used for the analysis of community structure. Scoring criteria were established from these metrics. The biotic index for each station was calculated as the average of the scores of all metrics. 29 species of fish were collected in the Hana River including 12 species of fish at station T1, 19 species at T2 and 24 species at T3. The biotic integrity index obtained in each station indicates that the highest value (3.7) was obtained at station T3 outside the park, the average value (3.3) at T2 in the park and the lowest (2.5) at station T1 in the northeast of the park. The biotic integrity index allowed to show a pollution gradient along the Hana River from southwest to northeast, the most polluted.