Trophic guilds of cichlid species in a floodplain river.

Abstract

Floodplains support a diverse cichlid community, yet the trophic ecology of these species is not well understood. This study investigated the dietary niches and trophic guilds of cichlid species in the Cross River floodplain. A total of 480 fish samples from eight cichlid species were collected from three locations (Itu, Obubra, Ikom) over 6 months (October 2019-March 2020). Dietary analysis revealed notable variations in food preferences among species, with algae being the dominant food for Tropheus sudanensis (63.8%) and Streptocara melanotheron (28.8%). Molluscs and crustaceans were primary foods for Oreochromis placidus (25% molluscs and 46.8% crustaceans), indicating a carnivorous feeding strategy. Oreochromis niloticus (57.3%) and Coptodon mariae (63.2%) showed a preference for plant parts, whereas Coptodon guntheri (89.5%) predominantly consumed insects. Correspondence analysis revealed that C. mariae and O. niloticus were strongly associated with plant parts, whereas Coptodon guineensis preferred crustaceans. Canonical correspondence analysis (CCA) identified four trophic guilds: insectivores, benthivores, herbivores and algivores, with two sub-guilds within the benthivores - crustacivores and molluscivores. The first CCA dimension explained 76% of the variance (inertia = 1.492), which was statistically significant (p < 0.01), confirming the distinct feeding strategies of the cichlids. These findings underscore the specialization within cichlid diets and the presence of specialized sub-guilds within the benthivores. It is recommended that future studies investigate the ecological roles of these trophic guilds in floodplain biodiversity conservation and ecosystem management.