Dieta de juvenis de Trachinotus carolinus (Actinopterygii, Carangidae) em praias arenosas na costa do Rio de Janeiro

Abstract

Diet of juvenile Trachinotus carolinus (Actinopterygii, Carangidae) in sandy beaches on coast of Rio de Janeiro, Brazil. We studied the diet of juvenile Trachinotus carolinus (Linnaeus, 1766) in sandy beaches of Sepetiba Bay (Rio de Janeiro, Brazil), between January 2000 and April 2001. We tried to evaluate the trophic plasticity of fish this species along a spatial gradient of wave exposure, seasonality, besides to evaluate ontogenetic changes in the diet. The Index of Relative Importance (IRI) was used to measure the food items, determined by their frequency of occurrence, numbers and weights. The subphylum Crustacea, mainly the order Mysidacea, Decapoda Emerita brasiliensis (Schmitt, 1935) and Cephalochordata, represented by Branchiostoma platae (Fitzinger, 1862) were dominant in the diet. In the most exposed zone (Barra de Guaratiba beach) with predominant sandy substrate, the diet was comprised mainly by Emerita brasiliensis and Cirripedia, this later item common in rocky shores at the beach edge; in the intermediate exposed beach (Muriqui beach), Mysidacea and Branchiostoma platae; in the most protected beach (Itacuruçá beach), Polychaeta, Mysidacea and Branchiostoma platae was predominant. No seasonal change was recorded for the use of Mysidacea, while Branchiostoma platae was the more consumed during the winter, Polychaeta in spring, Cirripedia and Emerita brasiliensis, in summer. Mysidacea was the predominate food in all size classes, while Polychaeta was used predominantly by fish smaller than 20 mm standard length (SL) and Emerita brasiliensis and Cirripedia, were consumed mainly by larger individuals than 40 mm in the most exposed beach only. The success in use of surf zones and sand beaches by this fishes species, it can be partly, due the opportunist trophic strategy that uses a wide variety of available resources on environmental. KEYWORDS.Feeding index, pompano, marine fishes, trophic ontogeny, surf zone. RESUMO.Estudamos a dieta dos juvenis de Trachinotus carolinus (Linnaeus, 1766) em praias da Baía de Sepetiba (Rio de Janeiro, Brasil) entre janeiro de 2000 e abril de 2001. Procuramos avaliar a plasticidade trófica de peixes desta espécie ao longo de um gradiente espacial com diferentes níveis de exposição às ondas, sazonalidade, além de avaliar mudanças ontogenéticas na dieta. Os itens alimentares foram analisados através do índice de importância relativa (IIR), determinado pelos valores das frequências de ocorrência, de número e de peso. Os itens de maior importância foram do subfilo Crustacea, ordens Mysidacea, e o representante da ordem Decapoda Emerita brasiliensis (Schmitt, 1935), além de Cefalochordata, representado por Branchiostoma platae (Fitzinger, 1862). Na zona de maior exposição às ondas (praia de Barra de Guaratiba) e com substrato predominantemente arenoso, a dieta foi constituída principalmente por Emerita brasiliensis e Cirripedia, este último presente nos costões rochosos que limitam a praia; na zona de exposição intermediária (praia de Muriqui), houve um predomínio de Mys...

Feeding ecology of the beach silverside Atherinella blackburni (Atherinopsidae) in a tropical sandy beach, Southeastern Brazil

“…Predation on insects could also be facilitated by strong pigmentation and subsequent visualisation on the water by the larger fish. Although insects occur in some studies (LASIAK, 1986;NIANG et al, 2010;PALMEIRA;MONTEIRO-NETO, 2010), the observed proportions in this study were much higher.…”

“…Moreover, the prevalence of crustaceans in the diet is common to species that actively explore the water column in search of food, such as A. blackburni (LASIAK; MCLACHLAN, 1987;PALMEIRA;MONTEIRO-NETO, 2010;NIANG et al, 2010;CONTENTE et al, 2010). Insects are the only item that probably is influenced by local conditions.…”

Trophic connectivity and basal food sources sustaining tropical aquatic consumers along a mangrove to ocean gradient

“…Lycengraulis grossidens, Selene vomer) (Rodrigues & Vieira 2010, Niang et al 2010). This hypothesis is corroborated by prior stable isotope studies showing that assimilation of estuarine-derived nutrients usually occurs in recipient consumers feeding at the base of the food chain (e.g., primary consumers).…”

Fish assemblages along a morphodynamic continuum on three tropical beaches

“…The classification of beaches is performed using several models, including those that consider the beach morphodynamics (Wright & Short, 1984) and the influence of tides (Short, 1982;Masselink, 1993). In the case of reflective beaches, wave action generates physical stress at these sites that affects sedimentary structure and makes food resources available for fish that can adapt to these conditions (Calliari et al, 2003;Vasconcellos et al, 2007;Niang et al, 2010). Moreover, fish in such environments, with physical conditions created by tides and waves, possess adaptations that may be morphological (Palmeira & Monteiro-Neto, DOI: 10.1590 2010), or even behavioural adaptations, such as migration to the intertidal zones or other habitats (Harvey, 1998).…”