Eleven ecomorphological attributes and diet of seventeen juvenile fish species were examined to test the hypothesis that morphological patterns determine resource uses in estuarine habitats. Species were separated according to the apparatus to food capture and habitat use (benthic or pelagic) in three different groups: (1) a group with depressed fish body, strong caudal peduncle and enlarged pectoral fins; (2) a second group laterally flattened with a wide protruding mouth, and (3) a third group strongly flattened with small pectorals fins. The following six trophic groups were organized based on prey categories: Zooplanktivores, Benthivores, Omnivores, Detritivores, Macrocarnivores and Insectivores. Significant results (PERMANOVA) between ecomorphological indices and habitat and between ecomorphological indices and trophic groups were found. These data indicate that similarity of ecomorphological forms, which minimize the influence of environment and partitioning of food, would help facilitate the co-existence of these fish when they are abundant in this tropical estuary.Onze atributos ecomorfológicos e a dieta de dezessete espécies de peixes juvenis foram examinados para testar a hipótese de que os padrões morfológicos determinam a utilização dos recursos em habitats estuarinos. As espécies foram separadas de acordo com o modo de captura do alimento e uso do habitat (bentônicos ou pelágicos) em três grupos distintos: (1) um grupo de peixes depressiformes, com forte pedúnculo caudal e nadadeiras peitorais alargadas; (2) um segundo grupo, compressiforme, com ampla boca protrusível, e (3) um terceiro grupo, fortemente achatado e com pequenas nadadeiras peitorais. Seis grupos tróficos foram organizados com base nas categorias de presas: Zooplanctívoros, Bentívoros, Omnívoros, Detritívoros, Macrocarnívoros e Insetívoros. Foram encontrados resultados significativos (PERMANOVA) entre os índices ecomorfológicos e o habitat e entre os índices ecomorfológicos e os grupos tróficos. Estes dados indicam que a similaridade ecomorfológica, que reflete o ambiente e o tipo de alimento consumido, facilitaria a coexistência desses peixes quando estes são abundantes neste estuário tropical.

Pessanha et al.: Trophic relationships of fish assemblages 135 Trophic relationships among fish assemblages in a mudflat within Brazilian marine protected areaThe present study on the temporal variations in diet and the trophic guilds of dominant fish species in a tidal mudflat, during the dry and rainy seasons. We aimed at classifying the diet composition of 17 species in the Mamanguape river estuary, northeastern Brazil, identifying the dominant food components and evaluating the effects of seasonality on the guild organization. Diet varied little between species and seasons; during the rainy season, the diets seemed to be more heterogeneous. According to the importance of prey in the diets, 5 primary feeding guilds were identified: (1) Detritivore, (2) Zooplanktivore, (3) Zoobenthivore-epifaune, (4) Zoobenthivore-infaune, and (5) Piscivore. Most fishes fed on a diverse range of food items but relied heavily on the zooplankton preys. Several fish species showed a tendency for a specialised diet, with almost all species showing some degree of opportunistic feeding. A high degree of diet overlap was found among some species; however, the presence of exploitative competition could not be determined. AbstrAct

Trophic relationships among fish assemblages on a mudflat within a Brazilian Marine protected areaThe present study deals with the temporal variations in diet and the trophic guilds of dominant fish species on a tidal mudflat during the dry and rainy seasons. We sought to classify the diet composition of 17 species in the Mamanguape river estuary, northeastern Brazil, identifying the dominant food components and evaluating the effects of seasonality on the guild organization. Diets varied little between species and seasons, though they seemed to be more heterogeneous during the rainy season. Five primary feeding guilds were identified, in accordance with the importance of prey in the diets: (1) Detritivore, (2) Zooplanktivore, (3) Zoobenthivore-epifaune, (4) Zoobenthivore-infaune, and (5) Piscivore. Most fishes fed on a diverse range of food items but relied heavily on zooplankton prey. Several fish species showed a tendency to a specialised diet, with almost all species showing some degree of opportunistic feeding. A high degree of diet overlap was found among some species; however, the presence of exploitative competition could not be determined. AbstrActZooplanctívora, (3) Zoobentívora-epifauna, (4) Zoobentívora-infauna, e (5) Piscivora. A maioria dos peixes predou uma variada gama de itens alimentares, mas fortemente baseados em presas do zooplâncton. Alguns peixes apresentaram tendência para uma dieta especializada, com quase todas as espécies mostrando algum grau de alimentação oportunista. Um alto grau de sobreposição de dieta foi encontrado entre as espécies; no entanto, a ocorrência de competição por exploração não foi observada. resumoDescritores: Dieta, Ecologia alimentar, Comunidades de peixes, Sobreposição alimentar, Estuário.