The role of macroinvertebrates in the diets of the dominant fish species in Lake Nokoué, Benin

Abstract

Between 2003 and 2006 the diets of 22 fish species, comprising approximately 90% of the Lake Nokoué fish biomass, were analysed. Macroinvertebrates dominated the diet of ten species, fishes were the preferential prey of six fish species, and detritus and phytoplankton dominated the diets of six others. Attempts were made to calculate the consumption by fish of the main zoobenthic invertebrate groups, and this was estimated at 344 g m² y-¹. Insects constituted only 10% of the invertebrates consumed, mainly by Chrysichthys nigrodigitatus. One third of the macroinvertebrates consumed by fish comprised annelids, 20% were small crustaceans and 40% comprised shrimps, molluscs and crabs. These results are compared with published information on benthic invertebrate production within the lake, and show that some groups of macroinvertebrates are not consumed in proportion to their biomass and productivity.