Abstract

Ecomorphological correlates were sought among 10 fish species of different life history traits in a tropical estuary. Results from gut contents analysis showed that fish species were classified into four trophic groups including detritivores, zooplanktivores, benthivores, piscivores and macrocarnivores. Resource partitioning among fishes was under the influence of their morphological attributes. Detritivores and zooplanktivores were both characterized by the possession of long gill raker and a wide mouth. The suction feeding mode has been hypothesized to explain the morphological convergence. Detritivorores have additionally a long digestive tract, long pectoral and dorsal fins, a short caudal fin, while zooplanktivores have otherwise big eyes. Benthic invertebrate feeders had big eyes, long dorsal fins, a long head prolonged by protrusive jaws. Piscivores and macrocarnivores were both characterized by the possession of a deep caudal peduncle, up-positioned eyes and a wide and deep mouth. However, the mouth size was more pronounced in strict piscivores, while macrocrustacean feeders had a longer head and long pectoral and dorsal fins. This study corroborates the consistency of the relationships between morphology and ecology in fish assemblages of tropical estuarine systems. Whatever the prey functional type, benthic foraging fishes were characterized by the possession of long paired fins.

Key words: Diet, morphology, resource partitioning, life history traits.