LINKING FISH MORPHOLOGY AND DIET TO EXPLAIN FOOD RESOURCE PARTITIONING IN RESERVOIR ECOSYSTEMS

This study investigated the association between feeding morphology and dietary composition among selected fish species from the Glen Alpine Dam, Limpopo Province, South Africa, to assess potential resource partitioning and trophic interactions. Results revealed an overlap in feeding morphology (elongated guts, increased body depth and enlarged eyes) between Mozambique tilapia Oreochromis mossambicus and Redbreast tilapia Coptodon rendalli, suggesting potential competition for food resources and feeding on prey that takes a longer time to digest. Mud (65.3 and 83.3 %F, respectively) and ostracods (2.8 and 16.7 %F, respectively) were common in their diets, with the former species also having high incorporation of algae (5.6 %F) and plants (2.8 %F). In contrast, Largemouth bass Micropterus nigricans exhibited distinct morphological adaptations with larger gape, jaw size and high velocity suction capacity, which were characteristic of their piscivorous diet. Morphological grouping of Southern Churchill Petrocephalus wesselsi, Limpopo Bulldog Fish Marcusenius krameri, Threespot barb Enteromius trimaculatus and African silver catfish Schilbe depressirostris reflected similarities in feeding traits (short guts) and potential dietary overlap, and this was reflected in their consumption of insects and zooplankton. Since impoundments are closed water bodies, the species present have managed to coexist by feeding on different prey items, as supported by the differences in their feeding morphology. The findings demonstrate that feeding morphology provides a useful framework for predicting trophic interactions and resource partitioning among the study species. This information can support ecosystem-based fisheries management by improving our understanding of species coexistence, food-web dynamics and sustainable management of inland fisheries. Keywords: food competition, Glen Alpine Dam, gut content, partitioning, predictor