Development of a fish-based index of biotic integrity (FIBI) to assess the quality of Bandama River in Côte d’Ivoire

The aim of this study was to develop effective tools based on fish assemblages, allowing the development of an effective assessment approach for the ecological status of running waters. Fish samples were collected using gill-nets with mesh sizes of 8, 10, 12, 14, 15, 18, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 and 80 mm. Forty sites were visited from October 2008 to September 2009 in the Bandama River. A large part of the data set on fish descriptors associated with environmental parameters was compiled from regional databases. For each of the fish assemblage descriptors, stepwise multiple linear regressions with habitat variables were carried out. The residuals of the models obtained were used as candidate metrics independent of natural environmental factors. Student t-tests used to compare each metric in reference and disturbed samples indicated significant difference (P < 0.05) for six metrics. The standard residuals of metrics selected were added to constitute the final index. This multimetric index of fish assemblage integrity could serve as a practical technical reference for conducting cost-effective biological assessments of lotic systems.