Community structure of the demersal fish of Sepetiba Bay, RJA year-long otter trawl survey in the Sepetiba Bay, Rio de Janeiro State, Brazil, was carried out in order to describe the fish community structure and their spatial and seasonal variations. Sampling carried out between July 1993 and June 1994, yielded 97 species, 70 genera and 38 families. Ariidae, Gerreidae, Sciaenidae, Carangidae and Sparidae families amounted 69,9% of the total catch in number, and Ariidae, Sparidae, Gerreidae, Haemulidae and Sciaenidae amounted 67,9% of the total weight. Genidens genidens, Gerres aprion, Cathorops spixii, Micropogonias furnieri and Chloroscombrus chrysurus were the most numerous species, each one contributing more than 5% of the total catches. Higher numbers of fishes were associated with low depths and transparencies of the inner Bay, while salinity is a quite stable environmental parameter ranging around 29%o most of the time all over the Bay. Numbers of fish are higher in Late Summer and Early Winter. Overall, most number and weight of fishes were higher in the inner Bay than in the outer area next to the sea limit, while the number of species was higher in the outer Bay. The high number of fish species suggests the important role played by the Sepetiba Bay as rearing and residence grounds for the fish community.Key words: Sepetiba Bay, ichthyofauna, coastal lagoons, fish, community. RESUMOUm programa de amostragens mensais de arrasto de fundo em sete estações de coleta na Baía de Sepetiba foi realizado entre julho de 1993 e junho de 1994 com o objetivo de descrever a estrutura da comunidade de peixes e suas variações espaciais e temporais. Noventa e sete espécies de peixes foram levantadas, compreendendo 70 gêneros e 38 famílias. As famílias Ariidae, Gerreidae, Sciaenidae, Carangidae e Sparidae, nesta ordem, foram as mais abundantes em número, contribuindo com 69,9% do total capturado, enquanto Ariidae, Sparidae, Gerreidae, Haemulidae e Sciaenidae somaram 67,9% do peso total. Genidens genidens, Gerres aprion, Cathorops spixii, Micropogonias furnieri e Chloroscombrus chrysurus, nesta ordem, foram as espécies mais abundantes, contribuindo cada uma com mais de 5% do número total de peixes capturados. O maior número de peixes foi associado às menores profundidades e transparências, enquanto a salinidade apresentou, na maior parte do tempo, valores estáveis em torno de 29%o. Maiores abundâncias de peixes ocorreram entre fins do verão e início do inverno. O número e peso dos peixes foram maiores na zona interna da Baía enquanto

This work was carried out from the assessment of the conservation status of the freshwater ichthyofauna from Bahia State. The inventory data and species distribution were obtained from the specialized scientific literature and representative ichthyological collections. A total of 281 native species was recorded in Bahia State, distributed in the Northeastern Mata Atlantica (NMA) and São Francisco (SFR) freshwater ecoregions. There was a larger number of species in the NMA (187 spp.), composed by several coastal basins, than in the SFR (134 spp.), composed by São Francisco river basin. Among the 30 families recorded, Characidae and Rivulidae were the most representative, with 53 and 48 species, respectively. The conservation status of 214 species was assessed and 33 of them (15%) were included in the IUCN threat categories. Of these, 11 species were classified as vulnerable (VU), 12 as endangered (EN), and 10 as critically endangered (CR). Most threatened species (n = 14) belongs to the family Rivulidae. The larger number of threatened species in the NMA: (n = 23) is mainly related to the high endemism of restricted-range species associated with the human occupation impacts along the coastal regions. In the SFR, most of threatened species are annual killifishes, which are locally disappearing due to increasing degradation of their temporary habitats.

While there is already a comprehensive understanding of the effects of environmental variables, such as dissolved oxygen, temperature and salinity, on the structure, biomass and metabolism of aquatic biota in estuarine habitats, the effect of sedimentation, a harmful underlying factor, remains unclear. The aim of this study was to assess the differences in fish assemblages along the freshwater to salt water gradient of a large tropical estuary, and to evaluate the effects on them of habitat disturbance associated with shallow water sedimentation in the intertidal areas. Fish and environmental variables were recorded in the upper, middle and lower salinity zones of the estuary at ebb tide in both the dry and wet seasons. Sediment samples associated with different levels of habitat disturbance were analysed using granulometry, and their organic content and dissolved oxygen levels were quantified. Water temperature, salinity, pH and dissolved oxygen levels were also measured. Habitat disturbance was found to be correlated with the density, biomass and richness of fish assemblages. A total of 77 species were recorded, forming two distinct fish assemblages, with the Eleotridae family dominating in the upper zone, and Gerreidae, Gobiidae and Tetraodontidae the most common in the middle and lower estuary. Changes in the structure of fish assemblages, including reductions in density, biomass and richness, were associated with disturbance to natural features, where muddy sediment was replaced by sandy sediment and the quantity of organic matter fell. Atherinella brasiliensis was the species which showed a preference for the disturbed areas in the middle and lower zones, while Dormitator maculatus showed a preference for them in the upper estuary. They may be taken as indicators of habitat disturbance due to shallow sedimentation.

ABSTRACT. DISTRlBUTlON AND RELATl VE ABUNDANCE 01' THE MARINE CATFISH (SILU-RI FORMES, ARIIDAE) lN SEPETIBA BAY, RIO DE JANEIRO. Marine catfish (Ariidae) are abundant resources in olter trawl fisheries carried oul aI Sepeliba Bay, Rio de Janeiro (La!. 22°54, 23°04'S; Long. 43°34', 44°10' W). Rel alive abllndance and distribution were assessed, based in 158 fi shing sampling at seven sites in lhe Bay, between July-1993 e June-1996. Five species were recorded in the following abundance rank order: Genidens genidens (Valenciennes, 1839), Calhorops f>pixii (Agassiz, 1829), Sciadeichlhys lunisculis (Valenciennes, 1840), Neluma barba (Lacépede,1803), and Bagre marinus (Milchill , 1814), the lalter have been caught in only two samples. Marine catfish showed higher abundance in lhe inner Bay, wilh indication of spatial segregation. G. genidens was abundant in ali sites ofthe inner Bay, C. spixii e N. barba, nearto rivers mouths, and S. lunisculis, being widespread in ali studied area. Sazonality was nol evident, with few exceptions in some of the three annllal cycles; G. genidens and S. /unisculis were more abundant in biomass in summer 1994/95 (G. genidens) and 1993/94 (s. lunisculú). G. genidens e N. barba show higher abundance (CPUE and biol1lass) between July-93 and June-95 and C. f>pixii e S hmisculis between July-95 and June-96. Total associalion index indicates a overall positive assoc iation al110ng ali species, with. higher Jaccard and Sorensen silllilarities coeftici ent for the pairs C. spixii/G. genidens, G. genidens/S. lunisculis, e C. spixii/S ltmisculis. Pearson linear correlation and Sperlllan rank indicate that G. genidens and N. barba are inversely correlated to C. spixii and S /unisculis. Spatial segregation strategy Illay be explaining the coexistence 01' the Illarine catfish at Sepetiba Bay. K.EY WORDS. Siluriformes, Ariidae, fish rcology, marine catfish, Sepetiba Bay A família Ariidae compreende os bagres marinhos e de água salobra, ocorrendo na zonas tropicais litorâneas, em águas pouco profundas e geralmente de fundo lodoso. Em geral procuram a desembocadura dos rios, estuários e regiões lagunares na época da desova (FIGUEIREDO & MENEZES 1978). São largamente

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