Distribution and abundance of the ichthyofauna of surf zone in sandy beaches of the Rio de Janeiro Municipality, Brazil, were studied aiming to detect seasonal and wave exposure gradient influences on the fish community structure. Quarterly samplings were performed at 10 sites according to the exposure degree (sheltered, exposed and very exposed) between January and November 2004, by using beach seines with hauls carried out perpendicular to the coastline. A total of 6,464 fishes in 38 species and 22 families were identified, mainly juveniles or small sized individuals. The families Clupeidae, Carangidae and Sciaenidae amounted to 79% of the total fish number and 61% of the total biomass. The following species amounted to 81% of the total weight were: Harengula clupeola (36%), Orthopristis ruber (14%), Mugil liza (10%), Trachinotus goodei (8%), Trachinotus carolinus (7%) and Umbrina coroides (6%). Three species showed the highest relative abundance, contributing each one more than 10% of the total number (Harengula clupeola, Umbrina coroides, e Trachinotus carolinus); but only T. carolinus showed a clear pattern, being more abundant in the sheltered beaches. The highest CPUEs (number of individuals and biomass) and number of species values occurred in the sheltered beaches (p < 0.05); none of these indicators showed significant seasonal differences (p > 0.05), although some trends were detected. The wave exposure degree was confirmed as a primary factor influencing the fish community structure, with sheltered sites probably associated to higher plankton availability, lesser turbulence and more substrate stability. A distribuição e abundância da ictiofauna na zona de arrebentação de praias arenosas do Município do Rio de Janeiro, Brasil, foram estudadas objetivando detectar variações sazonais ou influências do grau de exposição na estrutura da comunidade de peixes jovens. Amostras trimestrais foram realizadas em 10 praias sendo agrupadas de acordo com o nível de exposição (abrigada, exposta e muito exposta), entre Janeiro e Novembro de 2004, com os arrastos tendo sido efetuados perpendiculares à linha de costa. Foram registrados 6.464 peixes, distribuídos em 38 espécies e 22 famílias, com o predomínio de formas juvenis ou de pequeno porte. As famílias Clupeidae, Carangidae e Sciaenidae representaram 79% do número total de indivíduos e 61% da biomassa total. As espécies de maior participação na biomassa, representando 81% do peso total, foram Harengula clupeola (36%), Orthopristis ruber (14%), Mugil liza (10%), Trachinotus goodei (8%), Trachinotus carolinus (7%) e Umbrina coroides (6%). Três espécies apresentaram maior abundância relativa, tendo cada uma, contribuído acima de 10% do número total (Harengula clupeola, Umbrina coroides e Trachinotus carolinus), mas somente T. carolinus apresentou um padrão bem definido, sendo mais abundante nas zonas abrigadas. As maiores CPUEs (número de indivíduos e biomassa) e o número de espécies foram encontradas nas zonas abrigadas (p < 0,05); sazonalmente nenhum destes indicad...

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)

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.
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

Diel fluctuations in nearshore fish communities were studied at a sandy beach in south-eastern Brazil. A total of 192 samples were performed by beach seines, during 3-hour intervals throughout 48-hour periods, between spring 2005 and winter 2006. Mean biomass and number of species were significantly higher at night, while number of individuals did not differ between day and night. Major disruptions in the fish community occurred during the winter when the assemblages underwent restructuring. Harengula clupeola, Sardinella janeiro, Anchoa lyoleps and Umbrina coroides were the predominant species at night, while Atherinella brasiliensis, Pomatomus saltatrix and Trachinotus carolinus peaked during the day, although significant diel changes in community structure were recorded only in the summer. Biological interactions, behavioural variations and local constraints might explain diel differences in the fish distribution. This study confirms that changes in diel activity in juvenile fish species can differ in similar areas, even for a given species, and the causes of these changes needs to be investigated.

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