Resumen.-Larimus breviceps, Isopisthus parvipinnis y Paralonchurus brasiliensis son las 3 especies de Sciaenidae más abundantes en la Reserva Extractiva Marina de Corumbau, en Bahia, nordeste de Brasil. Se analizaron los cambios ontogenéticos y estacionales en las dietas de estas especies. Estos cambios pueden reflejar las adaptaciones y mecanismos de coexistencia utilizados por estas especies. El muestreo se llevó a cabo entre diciembre 2007 y septiembre 2008 con arrastreros. Los peces y las gambas fueron los principales recursos consumidos por estas 3 especies. Para L. breviceps y P. brasiliensis, Sergestidae fue el alimento dominante (junto con poliquetos para el segundo), mientras que los peces fueron el elemento más importante para I. parvipinnis. Se observaron valores bajos de amplitud de nicho para todas las especies. El Índice de Similitud de Morisita indicó baja superposición entre las dietas de las 3 especies en la mayoría de las estaciones del año, a excepción de L. breviceps y I. parvipinnis, que mostraron valores superiores al 80% en todas las estaciones, excepto en verano. Aunque estas especies mostraron diferencias en la posición y orientación de su boca, esencialmente utilizan los mismos recursos. El hábito de alimentación carnívoro, principalmente carcinófago, prevaleció entre los Sciaenidae estudiados.Palabras clave: Hábitos de alimentación, coexistencia, superposición de nicho, amplitud de nicho, nordeste de Brasil Abstract.-Larimus breviceps, Isopisthus parvipinnis, and Paralonchurus brasiliensis are the 3 most abundant species of Sciaenidae in the Marine Extractive Reserve of Corumbau in Bahia (northeastern Brazil). Ontogenetic and seasonal changes in the diet of these species were analyzed. These changes may reflect adaptations and coexistence mechanisms used by those species. Sampling took place between December 2007 and September 2008 with otter trawlers. Fishes and shrimps were the main resources consumed by these 3 species. For L. breviceps and P. brasiliensis, Sergestidae was the dominant food item (together with polychaetes for the latter) and fishes were the most important item for I. parvipinnis. Low values of niche breadth were observed for all species. The Morisita Similarity Index indicated a general pattern of low overlap between the diets of the three species analyzed in most of the seasons, with the exception of L. breviceps and I. parvipinnis, which showed values higher than 80% in all seasons, with the exception of summer. Although these species showed differences in the position and orientation of their mouth, they essentially use the same resources. The carnivorous feeding habit prevailed among the studied Sciaenidae, with predominance of the carcinophagous habit.

The objective of this study was to describe the marine ecosystem off northeastern Brazil. A trophic model was constructed for the 1970s using Ecopath with Ecosim. The impact of most of the forty-one functional groups was modest, probably due to the highly reticulated diet matrix. However, seagrass and macroalgae exerted a strong positive impact on manatee and herbivorous reef fishes, respectively. A high negative impact of omnivorous reef fishes on spiny lobsters and of sharks on swordfish was observed. Spiny lobsters and swordfish had the largest biomass changes for the simulation period ; tunas, other large pelagics and sharks showed intermediate rates of biomass decline; and a slight increase in biomass was observed for toothed cetaceans, large carnivorous reef fishes, and dolphinfish. Recycling was an important feature of this ecosystem with low phytoplankton-originated primary production. The mean transfer efficiency between trophic levels was 11.4%. The gross efficiency of the fisheries was very low (0.00002), probably due to the low exploitation rate of most of the resources in the 1970s. Basic local information was missing for many groups. When information gaps are filled, this model may serve more credibly for the exploration of fishing policies for this area within an ecosystem approach.

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