Foraging of rocky habitat cichlid fishes in Lake Malawi: coexistence through niche partitioning?

Abstract

The haplochromine cichlid fish communities of the rocky habitats of Lake Malawi are highly diverse; however, many species live side by side with apparently very similar resource requirements. There is a long-standing debate concerning whether these species partition their resources on a finer scale than has been previously reported or if species that are truly ecologically indistinguishable can coexist. A field study of food resource use was conducted to determine whether coexisting species segregate their diet and foraging sites. Significant differences between species were found, yet considerable inter-specific resource use overlap was commonplace. The data indicate that these cichlid species coexist both with and without niche differentiation. We propose that alternatives to niche differentiation should be considered to explain how many species coexist in Lake Malawi cichlid communities.