ABSTRACT Leptopanchax opalescens (Myers, 1942) is a small seasonal killifish endemic to coastal drainages in the state of Rio de Janeiro, Brazil. Leptopanchax opalescens was recaptured in temporary open vegetation pools (22°42.35’S, 43°41.59’W) in the hydrographic basin of the Guandu River, state of Rio de Janeiro, Brazil, after eight years without records. Information on habitat and population parameters (Capture per unit area (CPUA), size, sex ratio and length-weight relationship (LWR)) are given to provide subsidies for the conservation of this species. Specimens were captured during the rainy season (January-April 2020) in shallow pools (mean depth = 21 ± 12 s.d. cm), with relatively acidic pH (5.2 ± 0.8) and low concentrations of dissolved oxygen (3.5 ± 1 mg/L). The estimated CPUA of the population was 0.89 fish/m2. The total length (TL) of males ranged from 21.1 to 28.8 cm, and females ranged from 17.0 to 31.2 mm. Males were significantly larger (t-test = 2.04, p < 0.05) than females, which were in greater proportion (2.83Female: 1Male, p < 0.001). A positive allometric coefficient (b = 3.19) was found through length-weight relationship curve, indicating that individuals of the species gain proportionally more increment in weight than in length. Leptopanchax opalescens is a critically endangered species, and the results of this study contribute to the knowledge of the distribution, population structure and conservation of the species and its natural habitats.

ABSTRACT The gonadal development of the characin Astyanax aff. bimaculatus from Funil Reservoir, an impoundment in the middle reaches of the Paraiba do Sul River in southeastern Brazil was analysed through histological, histochemical and histometric techniques, and the spawning season was determined. Unbalanced sex ratio was found, with females outnumbering and reaching larger sizes than males. The following stages of oogenic cell development were identified for females: primary growth, pre-vitellogenic (cortical alveolar) and vitellogenic. In males, the following stages were determined: spermatogonia primary and secondary, spermatocyte primary and secondary, spermatid and spermatozoa. The spawning occurs most of the year, peaking in January-February, as indicated by the gonadosomatic index. In the peak of the spawning period, the condition factor and hepatosomatic indices decreased suggesting use of stored body energy reserves during the reproduction. Spawning in batches, small-sized oocytes and a long reproductive season suggest that Astyanax aff. bimaculatus fits to an opportunist strategy. Such strategy may facilitate the use of a wide range of lentic and lotic body waters in the Neotropical region.

RESUMO Estudos de idade e crescimento de peixes têm aplicação direta na biologia pesqueira e contribuem para medidas de conservação. Nosso objetivo foi atualizar informações sobre parâmetros de crescimento de Micropogonias furnieri utilizando leitura de anéis etários em otólitos sagittae, esperando que a população do Sudeste do Brasil alcance maior longevidade do que o reportado na literatura. Examinamos 286 indivíduos, capturados entre agosto de 2010 e julho de 2011, na Baía de Ubatuba, SP. O comprimento total variou de 200-480 mm. Foram determinados os parâmetros de crescimento: Machos, L∞ = 523,4 mm, k = 0,05 ano-1, t0 = -8,78 ano; Fêmeas, L∞ = 573,5 mm, k = 0,06 ano-1, t0 = -7,49 ano. O IM e a porcentagem do tipo de borda evidenciaram o padrão de formação anual de anéis no outono/inverno, coincidindo com mais baixas temperaturas e crescimento lento. Estes resultados diferem dos reportados para População I de Vazzoler (verão), e nós detectamos longevidade bem superior (45-48 anos) à descrita anteriormente.

ABSTRACT Studies on age and growth of fish populations have direct application in fisheries and contribute for policies of conservation. Our aim was update information on the Micropogonias furnieri growth parameters based on sagittae otoliths annulis readings, and we expected that the studied population from Southeast Brazil can reach more longevity than the reported in the available literature. We examined 286 individuals between August-2010 and July-2011 from Ubatuba Bay, SP. The Total Length ranged 200-480 mm. The determined growth parameters were: Males, L∞ =523.4mm, k = 0.05×year-1, t0 = -8.78 year; Females L∞ = 573.5mm, k = 0.06 × year-1, t0 = -7.49 year. The MI and % of edge type evidenced the formation of one ring per year during autumn/winter, coinciding with low temperature and low growth rate. These results differed from those reported for the Vazzoler’s Population I (summer), and we detected higher longevity (45-48 years) as compared with the recorded in the available information.

ABSTRACT Cynoscion leiarchus (Cuvier, 1830) is a coastal fish species that is widely distributed along the Western Atlantic coast, from Belize to Southern Brazil. In Brazil, C. leiarchus It is an important resource for commercial and artisanal fisheries. Our objective was to describe the oogenesis and spermatogenesis stages of the species and to estimate batch size and relative fecundity of a population at a tropical bay in southeastern Brazil. The examined specimens were obtained from artisanal catches that took place from July 2013 to June 2014. A total of 18 individuals (11 females and 7 males) were examined for histological analysis and 20 spawning-capable females were used to estimate fecundity. Five stages of oocyte development (primary growth, pre-vitellogenic, vitellogenic, oocyte maturation and atresia) and four stages of spermatocytes (spermatogonia, spermatocytes, spermatids, spermatozoa) were described in different phases of gonad development (immature, developing, spawning capable and regenerating), suggesting that spawning happens in batches, oocyte development is asynchronic and fecundity is indeterminate. Batch fecundity ranged from 100 × 103 to 866 × 103 oocytes undergoing final oocyte maturation, and relative fecundity ranged from 232 to 1,225 oocytes, averaging 467 oocytes per gram of ovary-free body weight. Fecundity tended to increase linearly with gonadal weight, total weight, total length, and age, but the highest linear correlation obtained was between fecundity and gonadal weight. This study provides the first information on the gonadal development of C. leiarchus from the Brazilian coast and is a baseline to compare with other populations and/or congeneric species.

The aim of this study was to assess the ecomorphological patterns and diet of four Characiformes fish species in a poorly physically structured tropical reservoir. We tested the hypothesis that body shape and diet are associated, because environmental pressure acts on the phenotype, selecting traits according to the available resources. Ten ecomorphological attributes of 45 individuals of each species - Astyanax cf. bimaculatus (Linnaeus, 1758), Astyanax parahybae Eigenmann, 1908, Oligosarcus hepsetus (Cuvier, 1829), and Metynnis maculatus (Kner, 1858) - , collected between February and November 2003, were analyzed, and the patterns were assessed using Principal Components Analysis (PCA). Diet similarity among fish species was assessed using cluster analysis on feeding index. The first two axes from PCA explained 61.73% of the total variance, with the first axis being positively correlated with the compression index and relative height, whereas the second axis was positively correlated with the pectoral fin aspect. Two well-defined trophic groups, one herbivorous/specialist (M. maculatus) and the other formed by two omnivorous/generalist (A. cf. bimaculatus, A. parahybae) and one insectivorous-piscivorous (O. hepsetus) were revealed by the cluster analysis. Astyanax. cf. bimaculatus and A. parahybae differed. The first has comparatively greater relative height, relative length of the caudal peduncle and lower caudal peduncle compression index. However, we did not detect a close correspondence between diet and body shape in the reservoir, and inferred that the ecomorphological hypothesis of a close relationship between body shape and diet in altered systems could be not effective.

The reproductive biology of Mugil liza Valenciennes, 1836 is described as a contribution to an elaborate management programm. A total of 243 specimens (89 males and 154 females) were collected in the Sepetiba Bay in south-eastern Brazil from July/2006 to June/2007. The gonadosomatic index (I G) and the sequential development of the ovaries observed through histological studies suggested that the spawning season ranged from May to August. The population reached total sexual maturity (L T100) at 550 and 570 mm total length (L T) for males and females, respectively. Females attained a larger size than males, and the sex ratio was female-biased for fish larger than 500 mm L T. The hepatosomatic index (I H) was significantly related to the I G, indicating that vitellogenesis mobilizes hepatic energy during reproduction. Mean fecundity was 3,080,000 oocytes. The presence of only two phases of oocyte development in ripe ovaries - a reserve stock and a clutch of post-vitellogenic oocytes - indicated that ovarian development is group synchronic and this species is characterized as a total spawner. The results suggest that establishing a closed fishing season from May to August and establishing a minimum size for capture of 350 mm L T would enhance stock conservation and production for future harvest seasons.

The present study compared losses of weight and length in specimens of Atherinella brasiliensis (Quoy & Gaimard, 1825) after fixation in formalin 10% during ten days, and posterior preservation in ethanol 70% for 45 days, in two solvents: freshwater and marine water. Additionally, correction factors were proposed to calculate the correction for weight and length from preserved specimens. The specimens were weighted and measured after collection (fresh), and with 10, 20, 27, 34, 41 and 55 days of fixation plus preservation. The largest losses in weight occurred during the first 20 days (10.35 ± 0.31% - freshwater; 11.29 ± 0.44% - marine water), continuing with lesser intensity up to the 27th day in freshwater dilution, and up to the 34th day in marine water dilution. Weight losses stabilized by the 34th day for both freshwater (11.77 ± 0.33%) and marine water (13.62 ± 0.41%). The largest losses in the total length for the two methods were also observed in the first 20 days (7.42 ± 0.27% - freshwater; 9.76 ± 0.26 - marine water), stabilizing after the 27th day in freshwater (8.60 ± 0.26%) and 20th day in marine water (9.76 ± 0.26%). The losses of weight and total length were significantly dependent on fish size, with smaller individuals suffering the most significant losses. Complete regression equations were proposed for the retro-calculation of fresh weight and total length from the preserved specimens for freshwater (Wfresh = 1.0536W P + 0.0416; TLfresh = 0.9588TL P + 5.8437) and marine water (Wfresh = 1.0868W P + 0.0451; TLfresh = 0.8621TL P + 10.425).

Este trabalho objetivou quantificar a variação do comprimento total e massa corporal para pós-larvas de Sardinella janeiro e determinar as equações de correção para o cálculo do comprimento total e da massa corporal a partir de espécimes preservados. Os peixes foram submetidos aleatoriamente a cinco métodos de preservação (congelamento - 20º C, formalina 2,5% e 5%, álcool 70% e 95%), e medidos o comprimento total (CT) e pesado a massa corporal (P) antes da preservação, e 5, 15, 30 e 60 dias após a preservação. Foram observadas perdas significantes no comprimento total e na massa corporal durante os cinco primeiro dias após a preservação, prosseguindo em menor intensidade até o 30º dia na maioria dos métodos. Exceções foram observadas para a massa corporal em congelamento e formalina 5%, com perdas ocorrendo mesmo depois de 30 dias de preservação. O grau de perdas para comprimento total e massa corporal foi significativamente dependente do tamanho dos peixes, com os menores indivíduos sofrendo as maiores perdas. O comprimento total e massa corporal de indivíduos frescos podem ser retro-calculados usando equações que descrevem a relação entre indivíduos frescos e após 60 dias de preservação para a maioria dos métodos, exceto para a massa corporal em congelamento.

This work aims to quantify the variation in total length and body mass for the early-juvenile Brazilian herring Sardinella janeiro and to determine total length and body mass correction equation to allow fresh measures to be calculated from preserved ones. Fishes were randomly assigned to one of five preservation methods (freezing at - 20º C, 2.5% and 5% formalin, 70% and 95% ethanol), and measured for total length (TL) and body mass (W) before preservation, and on days 5, 15, 30, and 60 after storage. Significant reductions in total length and body mass occurred during the first 5 days after preservation and continued to contract significantly at a lesser rate through 30 days in most methods. Exceptions were shown for body mass in freezing and 5% formalin, where the greatest losses occurred after 30 days of preservation. The degree of shrinkage for total length and body mass was very much dependent on fish size, with smaller specimens shrinking more than larger ones. The fresh total length and body mass can be back-calculated using equations that describe the relationship between fresh and preserved individuals after 60 days storage for all methods except for body mass in freezing.

A distribuição de manjubas (Clupeiformes, Engraulidae) foi descrita na Baía de Sepetiba, uma área costeira do Sudeste do Brasil, para determinar eventuais mecanismos de seleção de habitat. Dois programas de amostragem foram realizados; um usando arrasto de praia (1998/2000) para captura de juvenis, e outro, usando arrasto de fundo (1999/2000) para captura de adultos. Seis espécies representadas por quatro gêneros foram capturadas: Anchoa tricolor, Anchoa januaria, Anchoa lyolepis, Cetengraulis edentulus, Engraulis anchoita e Lycengraulis grossidens. Anchoa tricolor e A. januaria foram as espécies mais abundantes, com a primeira ocorrendo principalmente na zona externa da baía, enquanto a segunda com maior abundância na zona interna. Adultos A. tricolor são alvo de intensas pescarias comercial na baía durante a Primavera-Verão, enquanto E. anchoita, uma abundante espécie na plataforma continental, foi ocasionalmente capturada em grande numero durante o Outono. A seleção de hábitat, através do uso de diferentes áreas da baía, foi desenvolvida pelas duas espécies mais abundantes, um provável mecanismo para permitir a coexistência.

Distribution of anchovies (Clupeiformes, Engraulidae) was described in the Sepetiba Bay, a coastal area of Southeastern Brazil, to assess eventual mechanisms of habitat selection. Two fish sampling programmes were accomplished; one using beach seine (1998/2000) to catch juveniles in sandy beaches, and the other, using seines (1999/2000) to catch adults in deeper bay areas. Six species representing 4 genera were recorded: Anchoa tricolor, Anchoa januaria, Anchoa lyolepis, Cetengraulis edentulus, Engraulis anchoita and Lycengraulis grossidens. Anchoa tricolor and A. januaria were the most abundant species, with the former peaking in the outer bay, while the latter peaking in the inner bay. Adults A. tricolor are target of heavy commercial fisheries in the bay during Spring-Summer, while E. anchoita, an abundant species in the continental shelf, was occasionally caught in large numbers during the Autumn. The habitat selection, by using two different bay areas, was developed by the two most abundant species, a probable mechanism to enable their coexistence.

Orthopristis ruber (Cuvier, 1830) é uma espécie muito comum na costa brasileira, sendo encontrada em baias, onde figura entre os mais abundantes peixes nos arrastos de fundo. Este trabalho tem por objetivo avaliar a influência das condicionantes ambientais na distribuição espaço-temporal e no período reprodutivo de O. ruber na Baía de Sepetiba, uma área costeira semi-fechada no sul do Rio de Janeiro. Foi realizado um programa de arrasto de fundo, entre outubro de 1998 e setembro de 1999, em três zonas da baía, estabelecidas de acordo com sua proximidade do mar (interna, central e externa). Amostras mensais de peixes foram tomadas em triplicatas em cada ocasião de amostragem, bem como foram medidas as variáveis ambientais de temperatura, salinidade, transparência e profundidade. Abundância relativa foi avaliada com base nas CPUEs (Captura por Unidade de Esforço) em termos de número e de biomassa, enquanto o período reprodutivo foi determinado com o índice gonadossomático. Um total de 866 indivíduos foi capturado, com o tamanho variando entre 31 e 293 mm de comprimento total e proporção sexual de 1:1. Um maior número de peixes foi registrado em janeiro/fevereiro e em maio, embora não tenha sido encontrada diferença na abundancia relativa entre as estações do ano. Espacialmente, os maiores números e biomassas foram registrados na zona externa. Correlação positiva significativa foi encontrada entre a abundancia relativa e a profundidade, salinidade e transparência, e negativa com a temperatura. O período reprodutivo, indicado pelos maiores valores de índices gonadosomático (IGS), provavelmente ocorre de junho a setembro, coincidindo com as menores temperaturas. Esta espécie parece ter distribuição limitada às zonas mais externa da baia, próxima à influência com o mar, com maiores influxos no verão, como provável efeito da das Águas Centrais do Atlântico Sul (ACAS) que comprimem as Águas Costeiras (AC) para a baía.

Orthopristis ruber (Cuvier, 1830) is a very common species in the Brazilian coast, being found in large abundance in bays where they rank among the most numerical abundant species in bottom trawls. This work aims to assess environmental influences on spatial, temporal distribution and reproductive period of O. ruber in the Sepetiba Bay, a coastal semi-closed area in the Rio de Janeiro State. Monthly samplings were carried out using otter trawl from October 1998 to September 1999, in three Bay zones, defined according to the proximity of the sea (inner, middle and outer). Samples were taken as triplicate at each site as well as environmental measurements of water temperature, salinity, transparency and depth. Relative abundance was assessed by CPUE (capture per unit effort) in both number and weight. The reproductive period was determined by the gonadossomatic index. A total of 866 individuals was caught, with size ranging from 31 to 293 mm Total Length and sex ratio 1:1. Higher fish numbers and biomass were recorded in January/February and May, although no significant difference was found among seasons. Spatially, the highest number and biomass were recorded in the outer zone. Positive significant correlation between relative abundance and depth, salinity and transparency and negative with temperature were found. The reproductive period, indicated by the highest gonadosomatic index (IGS) occurred probably between June and September, coinciding with the lowest temperatures. This species seems to have distribution limited to outer bay zones, near to the sea influence, with the highest influxes in Summer, as a probable effect of the South Atlantic Central Waters (SACW) that compress Coastal Waters (CW) toward the bay.

As estruturas teciduais do trato gastrintestinal de Pimelodus maculatus La Cepède, 1803, do reservatório de Funil (22º30'-22º35'S; 44º35'- 44º40'W) foram descritas através das técnicas de hematoxilina-eosina (HE), tricômico Gomori, ácido Periódico de Schiff (PAS) e alcian blue (AB) pH 2,5. Objetivou-se a detecção de glicoproteínas (GPs) na mucosa através de uma análise histoquímica e caracterização de possíveis alterações ao longo do trato digestório destes peixes neste sistema de elevado grau de alteração. Cinqüenta e quatro indivíduos adultos, coletados entre abril de 2003 e julho de 2004 (CT=19-38 cm) foram utilizados. Na cavidade bucofaríngea, a mucosa apresenta-se com pregas longitudinais e o epitélio é do tipo estratificado pavimentoso. O esôfago apresenta o mesmo tipo de epitélio da cavidade bucofaríngea, destacando-se a predominância de células mucosas que tiveram forte reação aos métodos utilizados. O estômago foi diferenciado em região cárdica, fúndica e pilórica. A mucosa é continuamente revestida por um epitélio simples cilíndrico que apresentou reação positiva ao AB e PAS somente na superfície apical das células; a lâmina própria possui glândulas tubulares que se ramificam gradativamente e consistem de um tipo celular denominado oxinticopépticas, relacionadas com a síntese de ácido clorídrico e pepsinogênio. O intestino apresenta vilosidades revestidas por um epitélio simples cilíndrico com planura estriada e células caliciformes. Na camada submucosa do duodeno foi observada a abertura do colédoco, sendo o epitélio do tipo simples cilíndrico sem células caliciformes, positivo tanto ao PAS quanto ao AB. O ambiente eutrófico do reservatório de Funil não parece influenciar os padrões morfológicos das estruturas (esôfago, estômago e intestino) e não foram observadas modificações nas atividades das células mucosas.

Histological structures of the digestive traits of Pimelodus maculatus La Cepède, 1803, in the Funil reservoir (22º30'- 22º35'S; 44º35'- 44º40'W) were described using haematoxilin-eosin (HE), trichome Gomori, periodic acid Schiff (PAS) and alcian blue (AB) pH 2.5 techniques. The main aim of this study was to detect the levels of glycoproteins (GPs) in the mucous tunic based in histochemical techniques and to characterize eventual alteration in the digestive tract of this species in a polluted system. Fifty-four adult individuals collected between April-2003 and July-2004 (TL=19-38 cm) were examined. The mucosa showed longitudinal folds in the buccopharyngeal cavity, with a stratified squamous epithelium. The oesophagus showed epithelium similar to buccopharyngeal cavity, with a predominance of mucous cells, which reacted strongly with the used methods. The stomach showed three regions: cardic, fundic and pyloric. The mucous tunic is continuously revested by a single cylindrical epithelium which showed positive reaction to AB and PAS only at the apical cells surface. The proper tunic has tubular glands that ramify gradatively, being a cellular type named oxyntopeptic, related to chloridric acid and pepsinogenic cells synthesis. The intestine showed vilosities, with the mucous tunic revested by a single cylindrical epithelium with striated planure and caliciform cells. The duodenum submucosa layer was located at the coledocum opening, as a single cylindrical epithelium lacking caliciforms cells, reacting positively with both PAS and AB. The eutrophic environment of Funil reservoir did not seem to influence morphologic patterns of the structures (oesophagus, stomach and intestine) and no modification was observed in the mucous cells activity.

Coletas padronizadas de peixes e tomadas de variáveis ambientais foram realizadas em uma região de mangue na Baía de Sepetiba visando avaliar o papel deste sistema no ciclo de vida do peixe-rei Atherinella brasiliensis (Quoy & Gaimard, 1824). Um programa de amostragens mensais de arrastos de praia foi realizado, em cinco locais em uma área de mangue, entre agosto de 2002 e julho de 2003 nos períodos diurno e noturno, com variáveis ambientais tendo sido tomadas em cada local. As maiores abundâncias numéricas foram registradas no local da zona intermediária do canal principal, e as menores no local mais interno. As maiores contribuições em peso ocorreram no local mais externo e próximo da conexão com o mar. A abundância numérica foi diretamente correlacionada com a temperatura e salinidade, e o peso, com a salinidade e oxigênio dissolvido (p < 0,05). A população amostrada variou de 10 a 160 mm CT, com moda de 40-50 mm CT durante todo o ano em todos os locais. O recrutamento ocorre durante todo o ano, com picos (CT = 30 mm) de outubro a dezembro de 2002 e julho de 2003, tendo sido registrados após a ocorrência dos peixes de maiores tamanhos em setembro de 2002 e junho de 2003 principalmente no local mais externo. Os maiores indivíduos se concentraram no local mais externo de substrato arenoso, áreas mais propícias para reprodução de A. brasiliensis, com os recrutas dispersando-se ao longo de todos os locais do canal do mangue que são utilizados como área de criação. A afinidade por habitats bem estruturados e a capacidade de usar eficientemente sistemas semi-fechados foi confirmada para A. brasiliensis no manguezal de Guaratiba.

Fish and environmental variables were sampled in a mangrove area from Sepetiba bay to assess the role of this system in life cycle of the silverside Atherinella brasiliensis (Quoy & Gaimard, 1824). Standardized monthly sampling using beach seines were conducted at five sites, between August, 2002 and July, 2003 in daily (day/night) basis, with environmental variables being taken at each site. The highest numerical abundance was recorded in the intermediate sample area in the mangrove channel and the lowest in the innermost site. The highest weight occurred in the outermost site near to the sea connection. Numerical abundance was directly correlated with temperature and salinity, and weight with salinity and dissolved oxygen (p < 0.05). Size ranged from 10 to 160 mm TL, with modes of 40-50 mm TL occurring all over the year in all sites. Recruitment occurred all year round but peaks (TL = 30 mm) in October-December, 2002 and July, 2003 were recorded afterwards the records of larger fishes (September, 2002 and June, 2003) mainly in the outermost site. The largest fishes concentrated in the sandy substrate of the outermost sites, areas more suitable for A. brasiliensis spawning, with recruits dispersing all over the mangrove areas, which are used as rearing grounds. The affinity for highly structured habitats in mangrove and the capacity to use efficiently semi-closed systems was confirmed for A. brasiliensis in Guaratiba mangrove.

Foram coletados peixes e medidas as variáveis ambientais na Baía de Sepetiba, uma baía tropical do Sudeste do Brasil. O objetivo foi determinar influências ambientais na distribuição de quatro espécies abundantes de Sciaenidae Micropogonias furnieri (Desmarest, 1823), Ctenosciaena gracilicirrhus (Metzelaar,1919), Cynoscion leiarchus (Cuvier,1830) and Menticirrhus americanus (Linnaeus, 1758) para testar a hipótese de partição do hábitat. Amostragens foram feitas entre Junho de 1993 e Julho de 1996 em três zonas da baía (externa, central e interna). A profundidade foi a mais importante variável ambiental que influenciou a distribuição dos peixes, seguida pela transparência. M. furnieri mostrou uma correlação negativa significante em relação à profundidade, transparência e salinidade, enquanto C. gracilicirrhus evidenciou uma situação oposta. As maiores densidades de C. leiarchus ocorreram nas menores temperaturas, enquanto M. americanus não parece ter preferências por nenhuma das variáveis ambientais examinadas. A separação espacial, principalmente entre M. furnieri e C. gracilicirrhus, parece ser uma estratégia desenvolvida para coexistirem na Baía de Sepetiba, com M. furnieri sendo mais adaptada para suportar as condições ambientais mais difíceis da zona interna. As outras três espécies, que utilizam mais a zona externa, parecem ser restritas às mais estáveis condições, onde influências das águas oceânicas são mais intensas.

We sampled fish and measured environmental variables in the Sepetiba Bay, a tropical embayment at Southeastern Brazil. The aim was to assess environmental influences on distribution of four abundant species of Sciaenidae Micropogonias furnieri (Desmarest, 1823), Ctenosciaena gracilicirrhus (Metzelaar, 1919), Cynoscion leiarchus (Cuvier, 1830) and Menticirrhus americanus (Linnaeus, 1758) to test the habitat partition hypothesis. Samples were taken between June 1993 and July 1996, at three bay zones (outer, central and inner). Depth was the most important environmental variable to influence fish distribution, followed by transparency. M. furnieri showed significant negative correlation to depth, transparency and salinity, while C. gracilicirrhus showed the opposite situation. The highest densities of C. leiarchus occurred in the lowest temperature, while M. americanus did not showed preferences for any of the examined environmental variables. Spatial separation, mainly between M. furnieri and C. gracilicirrhus, seems to be the strategy developed to coexist in the Sepetiba Bay, with M. furnieri being more adapted to copy with harsh environmental conditions of the inner bay. The other three species, which use mostly the outer bay zone, seem to be restricted to more stable conditions, where influences from oceanic waters are more intense.

Padrões na diversidade de peixes ao longo de quatro unidades geográficas (superior, médio-superior, médio-inferior e inferior) no rio Paraíba do Sul foram estudados com a finalidade de avaliar tendências de variações espaciais (unidades geográficas) e temporais (períodos de cheia e seca). Vinte e cinco locais foram amostrados entre Dezembro de 2002 e Março de 2003 (verão/cheia) e, entre Agosto e Novembro de 2003 (inverno/seca). Os peixes foram capturados com um esforço padronizado, utilizando redes de espera, tarrafas e peneiras. Um total de 81 espécies foram registradas compreendendo 9 ordens, 29 famílias e 55 gêneros. Characiformes apresentaram maior número de espécies (28) seguido de Siluriformes (23). Perciformes, principalmente Tilapia rendalli e Geophagus brasiliensis, e Cyprinodontiformes com destaque para Poecilia vivipara e Poecilia reticulata, foram os grupos numericamente mais abundantes, enquanto Siluriformes, principalmente Hypostomus luetkeni, e Perciformes com Geophagus brasiliensis apresentaram maior contribuição em biomassa. Poecilia vivipara foi encontrada apenas no período de seca. Espacialmente, Hoplosternum littorale predominou no trecho médio-superior, Pimelodus fur, Hypostomus luetkeni, Glanidium albescens no trecho médio-inferior, e Loricariichtys spixii e Prochilodus lineatus no trecho inferior. O número de espécies e a riqueza de Margalef apresentaram um aumento do trecho superior para o inferior, principalmente durante o período de cheia. Espécies que apresentaram ampla distribuição ao longo do rio (G. brasiliensis, Oligosarcus hepsetus e P. reticulata) são consideradas oportunistas por se aproveitarem dos recursos disponíveis em ambientes pobres, refletindo o estado de alterações do rio. Diferenciações na fisiografia ao longo da extensão longitudinal da bacia não coincidiram com mudanças nas assembléias de peixes, sugerindo que fatores associados a alterações de hábitats poderiam estar estruturando a comunidade de peixes a nível local.

Diversity patterns of fish assemblages along the four geographic units (upper, middle-upper, middle-lower and lower reaches) of the Paraíba do Sul river were studied aiming to assess spatial (geographic units) and seasonal (wet/dry periods) variations. Twenty-five sites were sampled between December 2002 and March 2003 (summer/wet) and, August to November 2003 (winter/dry). Fish were caught by a standardized effort, using gill nets, cast nets and mesh trays. A total of 81 species were recorded comprised in 9 orders, 29 families and 55 genera. Characiformes showed the highest number of species (28) followed by Siluriformes (23). Perciformes, mainly Tilapia rendalli and Geophagus brasiliensis, and Cyprinodontiformes, mainly Poecilia vivipara and Poecilia reticulata, were the most numerically abundant groups, while Siluriformes, mainly Hypostomus luetkeni, and Perciformes, mainly Geophagus brasiliensis showed the highest biomass. Poecilia vivipara was recorded only in dry period. Spatially, Hoplosternum littorale predominated in the middle-upper reaches, Pimelodus fur, Hypostomus luetkeni, Glanidium albescens in the middle-lower, and Loricariichtys spixii and Prochilodus lineatus, in the lower reach. Number of species and Margalef's richness showed an increase from the upper to the lower river reaches, mainly during the wet period. Species widely distributed along all over the river extent (G. brasiliensis, Oligosarcus hepsetus e P. reticulata) are opportunistic and can use the available resources despite poor environmental conditions, reflecting the state alteration of the river. Differentiation on the physiography throughout the longitudinal extent of the basin does not match shifts in fish assemblages, suggesting that factors associated to habitat alterations could be structuring fish community at local scale.

Efeito do tempo de conservação dos espécimes sobre a qualidade dos microincrementos em otólitos sagittae de Anchoa tricolor (Agassiz) (Clupeiformes, Engraulidae). O número de microincrementos em otólitos sagittae de espécimes de pós-larvas de Anchoa tricolor (Agassiz, 1829) fixadas em formol 10% foram comparados em diferentes períodos de conservação (quatro dias versus quatro anos). Diferenças significativas foram encontradas no número de microincrementos para pós-larvas variando de 20-26 mm de comprimento total (CT), com médias de 18,6 microincrementos (± 0.75 erro padrão) para peixes preservados por quatro anos, e 35,3 microincrementos (± 1.28 erro padrão) para peixes preservados por quatro dias. Portanto, o número de microincrementos em otólitos de pós-larvas preservados por longos períodos pode não ser adequado para inferências de taxas de idade ou crescimento. Adicionalmente, não foram detectados ou extraídos otólitos em pós-larvas menores do que 20 mm CT devido a maior composição de matéria orgânica durante esta fase do ciclo de vida.

We compared the number of microstructure of Anchoa tricolor (Agassiz, 1829) post-larvae sagittae otoliths in specimens fixed in formalin 10% in different periods of conservation (four days versus four years). Significant differences were found in the number of microstructure for post-larvae ranging from 20-26 mm total length (TL), with averages of 18.6 microstructures (± 0.75 standard error) for fishes preserved for four years, and 35.3 microstructures (± 1.28 standard error) for fishes preserved for four days. Therefore, the number of post-larvae otoliths microstructure preserved for long periods can not be suitable to infer age or growth rates. Additionally, we failed in detecting and extracting otoliths in post-larvae smaller than 20 mm TL preserved due to its comparatively higher organic matter composition, mainly during the early life cycle.