O objetivo deste estudo foi determinar as mudanças espaciais e ontogenéticas na dieta dos linguados Citharichthys spilopterus Günther, 1862 e Symphurus tessellatus (Quoy & Gaimard, 1824) na Baía de Sepetiba. A área de estudos foi dividida em três zonas (interna, central e externa), onde foram realizados arrastos de fundo diurnos no período entre outubro/1998 a setembro/1999. C. spilopterus apresentou os maiores Índices de Importância Relativa (IIR) para Mysidacea (0.3359) e Amphipoda (0.0805), enquanto S. tessellatus apresentou maiores IIR para Amphipoda (0.7515) e Polychaeta (0.2586). A elevada porcentagem (67,61%) de estômagos vazios em S. tessellatus sugere atividade alimentar noturna. Os espécimes de menor tamanho (CT < 115 mm) de C. spilopterus alimentaram-se de Mysi-dacea na três zonas e os maiores (CT > 115 mm) de Polychaeta na zona interna, Gobiidae na central e Decapoda na externa. Os menores espécimes (CT < 155 mm) de S. tessellatus alimentaram-se principalmente de Amphipoda e os maiores (CT > 155 mm) de Polychaeta na zona interna, e de Amphipoda e Polychaeta na zona externa. Citharichthys spilopterus apresentou maior tamanho de boca e olho, e se alimentou de organismos associados à coluna da água próxima, tendendo a uma dieta mais especialista quando comparado com S. tessellatus que se alimentou de organismos sobre fundo. Apesar das duas espécies terem se alimentado basicamente de Crustacea, apresentaram baixa sobreposição alimentar com 0,1972, provavelmente podendo ser esta a estratégia de separação trófica desenvolvida para permitir a coexistência destas duas espécies relacionadas na Baía.

The aim of this study was to assess the spatial and ontogenetic changes in diet of the flatfishes Citharichthys spilopterus Günther, 1862 and Symphurus tessellatus (Quoy & Gaimard, 1824) in the Sepetiba Bay. The studied area was divided in three zones (inner, central e outer), where bottom trawls were performed during the day, from October 1998 to September 1999. Citharichthys spilopterus showed higher Indices of Relative Importance (IRI) for Mysidacea (0.3359) and Amphipoda (0.0805), while S. tessellatus showed the highest IRI for Amphipoda (0.7515) and Polychaeta (0.2586). The high percentage (67.61%) of empty guts in S. tessellatus suggests nocturnal feeding activity. Smaller sized individuals (TL < 115 mm) of C. spilopterus fed on Mysidacea in the three bay zones, while the larger sized (TL > 115 mm) fed on Polychaeta the inner zone, Gobiidae in the central and Decapoda in the outer. The smaller individuals (TL < 155 mm) of S. tessellatus fed mainly on Amphipoda while the largest (TL > 155 mm) fed on Polychaeta in the inner zone, and Amphipoda and Polychaeta in the outer zone. Citharichthys spilopterus, shows comparatively larger mouth and eye, and feed on organisms in the water column nearby, with a more specialized feeding habit, compared with S. tessellatus, which feed on organism on the substrate. Although the two species feed basically on Crustacea, they present low overlaping in the diet (0.197), and this is probably the trophic strategy developed to allow the coexistence of these two closely related species in the Bay.

A year-long beach seine survey at the continental margin of Sepetiba Bay, Rio de Janeiro State, Brazil, catching mainly young-of-the-year and juvenile fishes was carried out from July 1983 to June 1984, in order to describe the community structure and their spatial and seasonal variations. Fifty-five monthly samplied carried out in five sites in the marginal surf zone waters yielded 11,463 fishes in 82 species, 59 genera and 31 families. Gerreidae, Engraulidi-dae, Atherinidae and Ariidae families amounted 87.01% of the total catch in number, and 81% in weight. Cerres aprion Cuvier, 1829, Anchoa januaria (Steindachner, 1879), Anchoviella lepidentostole (Fowler, 1911), Atherinella brasiliensis (Quoy & Gaimard, 1824) and Neluma barba (Lacépède, 1803) were the most numerous species, each one contributing more the 4% of total catch. Overall, both spatial and seasonal changes in fish were not evident although most individuais were more abundant in the outer Bay. The high number of fish species in this area, suggest the important role played by the Sepetiba Bay in the fish community to where many species probably migrate from the nearby sea and stay in the Bay during part of their life cycle. Decreasing diversity and high dominance of a few number of species seem to indicated a trend of environmental deterioration in the Sepetiba Bay over the last decade, as this date are compared whith similar sampling program carried out in 1993/94. It same to indicated that changes in fish populations which use this area as rearing grounds, occurred during their early life history.

Marine catfish (Ariidae) are abundant resources in otter trawl fisheries carried out at Sepetiba Bay, Rio de Janeiro (Lat. 22º54, 23º04'S; Long. 43º34\ 44º10'W). Relative abundance and distribution were assessed, based in 158 fishing sampling at seven sites in the Bay, between July-1993 e June-1996. Five species were recorded in the following abundance rank order: Genidens genidens (Valenciennes, 1839), Caihorops spixii (Agassiz,1829), Sciadeichthys lunisculis (Valenciennes, 1840), Nelunia barba (Lacépède, 1803), and Bagre marinus (Mitchill, 1814), the latter have been caught in only two samples. Marine catfish showed higher abundance in the inner Bay, with indication of spatial segregation. G genidens was abundant in ali sites of lhe inner Bay, C. spixii e N. barba, near to rivers mouths, andS lunisculis, being widespread in ali studied area. Sazonality was not evident, with few exceplions in some of the three annual cycles; G. genidens and S. luniscutis were more abundant in biomass in summer 1994/95 (G. genidens) and 1993/94 (S. luniscutis). G. genidens e N. barba show higher abundance (CPUE and biomass) between July-93 and June-95 and C. spixii e S. luniscutis between July-95 and June-96. Total association index indicates a overall positive association among ali species, with. higher Jaccard and Sorensen similarities coefficient for the pairs C. spixii/G. genidens, G. genidens/S. luniscutis, e C. spixii/S. luniscutis. Pearson linear correlation and Sperman rank indicate that G. genidens and N. barba are inversely correlated to C. spixii and S. luniscutis. Spatial segregation strategy may be explaining the coexistence of the marine catfish at Sepetiba Bay.