Márcio de Araújo Silva

Efeito do grau de exposição às ondas sobre a comunidade de peixes juvenis em praias arenosas do Município do Rio de Janeiro, Brasil

Vasconcellos, R.M., Santos, J.N.S., Silva, M.A. & Araujo, G. Effect of the wave exposure gradient on juvenile fish community in sandy beaches of the Rio de Janeiro City, Brazil. Biota Neotrop. Jan/Apr 2007 vol. 7, no. 1 http://www.biotaneotropica.org.br/v7n1/pt/abstract?article+bn01907012007 ISSN 1676-0603. 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), 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.

Distribution and relative abundance of anchovies (Clupeiformes-engraulididae) in the Sepetiba Bay, Rio de Janeiro, Brazil

Distribution and relative abundance of juvenile fish of the family Engraulididae in the Sepetiba Bay, Rio de Janeiro, Brazil was assessed to detect patterns of use of the shallows during their early life cycle. Two yearly cycle (March-1996 to February-1997 and March-1997 to February-1998) were studied by a total of 120 beach net samples at five sites, two of them located in the inner Bay and three in the outer Bay near to the sea limit. Six Engraulididae species were identified in two genera: Anchoa januaria, Anchoa marinii, Anchoa tricolor, Anchoa lyolepis, Anchoviella lepidentostole and Anchoviella brevirostris, mainly juveniles in their early life cycle. A. januaria, A. brevirostris, A. lepidentostole and A. tricolor, in decreasing order, were the top numerical abundant species, while A. tricolor and A. januaria showed the highest weight contribution, amounting approximately to 90% of the total number of fish. Spatially, A. tricolor, A. lyolepis and A. marinii distributed mainly in the outer Bay. A. januaria show higher abundance in the inner Bay, while the species of genera Anchoviella show an ample distribution, without a particular zone of higher occurrence. Seasonally, only A. januaria, A. lepidentostole and A. brevirostris presented a clear pattern of occurrence, peaking in the Autumn.

Diel seasonality in fish biodiversity in a sandy beach in south-eastern Brazil

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.

Habitat selection by anchovies (Clupeiformes: Engraulidae) in a tropical bay at Southeastern Brazil

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.

Influência das variáveis ambientais na fauna acompanhante na pesca da manjuba Anchoa tricolor (Agassiz) (Actinopterygii, Engraulidae) na Baía de Sepetiba, Rio de Janeiro

Anchoa tricolor (Agassiz, 1829) is the only anchovy of commercial importance in Sepetiba Bay, supporting an intensive commercial fishery by small sized seine boats provide of hydroacustics sounder detecting device. This study analyses the accompanying fauna in the A. tricolor fishery, and the influence of environmental parameters in fish composition. Seven samples were taken with a seine net between March and September 1999, capturing 114,430 fish, comprising 17 species and 11 families. Engraulidae and Clupeidae were the most abundant families, accounting to 94.2 % of the total number of fish. A. tricolor was the most abundant species contributing to more than one half of the total numerical abundance, followed in decreasing order by Anchoa januaria (Steindachner, 1879), Sardinella brasiliensis (Steindachner, 1789) and Harengula clupeola (Cuvier, 1829). A. tricolor showed a highly significant positive correlation with salinity, transparency and depth. A. januaria showed the opposite, being inversely correlated to these parameters and directly correlated to temperature. Clupeidae, on the other hand, seems to show a wider distribution in relations to these environmental parameters.

Distribuição e abundância de tainhas e paratis (Osteichthyes, Mugilidae) na Baía de Sepetiba, Rio de Janeiro, Brasil

Variations in the fish populations of mullets were assessed aiming to detect trends in abundances during their early life cycle and relationship with environmental parameters. Fish were sampled between August 1994 and July 1997 using a beach scine and environmental parameters of water temperature, salinity and transparency were taken at each sampling. Five sites were systematically sampled, two of them in the inner Bay, and three in the outer Bay near to the sea limit. Three Mugilidae species were identified: Mugil liza Valencienes, 1836; Mugil curema Valencienes, 1836 and Mugil platanus Gunter, 1880; mostly juveniles in their early life cycle, being M. liza the most abundant species. Overall all mullets were more abundant in the inner Bay, where transparencies values lower and temperature values higher.

Spawning season, recruitment and early life distribution of Anchoa tricolor (Spix and Agassiz, 1829) in a tropical bay in southeastern Brazil

The pattern of the use of the Sepetiba Bay, a semi-closed 450 km(2) area in southeastern Brazil, by Anchoa tricolor was investigated to assess spawning period, recruitment and to detect spatial-temporal patterns of this major fishery resource. Fishes were sampled by seine nets, from spring, 1998 to winter, 1999 and by beach seine, from spring, 1998 to winter, 2000. Reproductive season, measured in terms of GSI, gonad development and appearance of recruits, indicate that reproduction occurs from August to March, when they reach the best condition. Recruitment peaks in winter/spring at sandy beaches where they stay until late summer, moving toward deeper bay areas during autumn. After that, they join adults and perform movements between the bay and the adjacent continental shelf to reproduce.