Food habits and feeding ecology of an estuarine fish assemblage of northern Pacific Coast of Ecuador

Resumen

Abstract. In order to analyze trophic relationships occurring within an estuarine fish assemblage in northern Ecuador, 271 stomachs from 12 species were examined. Percent by number (%N) was used to establish trophic organization applying Levins ’ dietary breadth, Pianka’s dietary overlap index and diet Bray Curtis Coefficient to evaluate interespecific relationships. Two planktophagous and 10 carnivorous species were defined with low dietary breadth; the former are species whose diet is based mainly on diatoms. The latter is largely composed by predators of fishes, decapods larvae, shrimps, crabs, polychaetes and bivalves. Of 66 possible dietary overlaps, two were found statistically significant and three functional groups were established. The first one composed by shrimps and mantis shrimp consumption, the second one distinguished by plankton feeders and the third one made up with species, which fed upon shrimps and crabs. These preliminary results suggest partitioning of food resources among these 12 estuarine species, which may favor their coexistence. Key words: mangrove fishes, diet, trophic structure, resource partitioning. Resumen: Relaciones tróficas de un ensamble de peces estuarinos en el Pacífico Norte de Ecuador. Se analizaron las relaciones tróficas de un ensamble de peces estuarinos del norte del Pacífico ecuatoriano a partir de las dietas de 271 individuos pertenecientes a 12 especies. A partir del porcentaje en número