Diet of three juvenile fish species of the coastal zone of a Southwest Atlantic beach, Brazil

Surf zones are associated with a shelter area, nursery and feeding for several species of fish. In this study, the dietary habits of three species of fish with demersal habits (Gulf kingcroakerMenticirrhu gracilis, Whitesea catfishGenidens barbusand Barbu Polydacytlus virginicus), were verified in the surf zone area of an active urban beach of Baixada Santista, concerning structure in size, day and night abundances and overlapping diets. Atotal of 617 fish were analyzed, of which 362 were 194 were G. barbusand 61 were P. virginicus. Stomach contents, represented in Relative Importance Index diagrams, showed that the bivalve Donax gemmulais the most important food item for M. gracilis, scales of Teleostei for G. barbusand Euphausiacea for P. virginicus. In order to evaluate the similarity of the diets, the Macarthur & Levins indices and a cluster analysis with the Bray-Curtis distance were applied revealing that the diet is 44% different between G. barbusand M. gracilis, 5% between G. barbusand P. virginicusand of 84% between M. gracilisand P. virginicus. Anthropogenic waste like plastic, nylon, metal pieces, were only occasionaly observed.(AU)

Ingestion of microplastic by ontogenetic phases of Stellifer brasiliensis (Perciformes, Sciaenidae) from the surf zone of tropical beaches.

Microplastics (<5 mm) are present in marine ecosystems worldwide where they can be ingested by a wide range of organisms from different trophic levels. In this study we analyzed the gastrointestinal tract of 443 specimens of Stellifer brasiliensis (124 juveniles, 254 subadults, and 65 adults) sampled in tropical beaches adjacent to the Paraíba River estuary. We found 1-3 microplastics in 42 fishes (9.48%), averaging 1.31 ± 0.52 microplastics per fish. The number of ingested microplastics by the different ontogenetic stages was statistically similar, but the adults had a higher ingestion frequency (13.8%). Among subadults, the condition factor of fishes that ingested microplastics was significantly smaller (p < 0.05) than those that had not ingested them. The ingestion of microplastics by the different ontogenetic stages of S. brasiliensis reflects the availability of this pollutant in the studied environment and highlights the vulnerability of fishes and other organisms through food webs.

Fishing marine debris in a northeast Brazilian beach: Composition, abundance and tidal changes.

This study aims to examine the composition and the spatial/tidal changes of marine debris caught with a fishing net during a fishery survey in two different areas of a sand beach at the northeast of Brazil. Samples were conducted weekly, at each moon phase, for two months using a beach seine net in the surf zone. Abundance of debris were estimate by swept area (items·km-1 and g·km-1). A total of 12 categories of debris were recorded. Plastic - both hard and soft types - was the most abundant debris category. Most fragments were classified as macro (20-100 mm) and mega debris (>100 mm). Significant differences (P < 0.05) between areas and tides were registered for plastic, metal and cloth. Spring tides were responsible for the high rates of marine debris found in the surf zone of Miramar beach. The results demonstrate the occurrence and abundance of litter in this fish nursery area and reinforce the need and importance of environmental protection and educational programs. CAPSULE ABSTRACT: Marine debris caught by a fishing net in the surf zone of Brazilian beach.

Fishing with trammel nets in the Casino Beach, RS, Brazil / A pesca com rede de cabo na praia do Cassino, RS, Brasil

Surf-zone trammel nets is a traditional artisanal fishing activity that take place along the coast of Rio Grande do Sul (RS) state, Brazil. In this study we analyze the seasonal variations in catches of Surf-zone trammel nets at Cassino Beach, RS, and report the list of fish species caught, their size distribution and variations in caught with mesh size. Fishermen were interview in the field soon after they bring the caught to the shore and fish species identified and measured. Net dimensions and mesh size was also inquired. Twenty-four fish species were identified and Trachinotus marginatus (plata pompano), Micropogonias furnieri (whitemouth croaker), Mugil liza (striped mullet), Menticirrhus americanus (kingcroaker) sum-up to 70% of the total catch. The larger abundance (CPUE = 11.27 ind. / 10m * 12h) and higher species richness (S = 22) occurred in the fall, as opposite to winter, were, smaller catches (CPUE = 2.91 ind. / 10m * 12h) and low number of species (S = 6) were reported. The dominant species and their frequencies varied seasonally. The diversity of mesh size used was non selective for the dominate species (T. marginatus). The main problems involving the use of surf-zone trammel nets is their low selectivity, since most of the individuals caught are juveniles of different species.

A pesca com rede de cabo é uma atividade artesanal de beira de praia que ocorre ao longo de toda a costa do Rio Grande do Sul e na qual se utiliza redes de tresmalhe feiticeiras na zona de arrebentação. O estudo objetivou analisar variações sazonais das capturas pela pesca com rede de cabo na praia do Cassino, RS, identificando as espécies de peixes, estrutura de tamanho dos indivíduos e suas relações com diferentes tamanhos de malha. Foi realizada a identificação das espécies, biometria dos indivíduos capturados e entrevistas semiestruturadas para caracterização das capturas e petrechos de pesca. Vinte e quatro espécies foram identificadas, entre as quais, Trachinotus marginatus (pampo), Micropogonias furnieri (corvina), Mugil liza (tainha), Menticirrhus americanus (papa-terra) que representaram 70% das capturas e ocorreram com elevado número de indivíduos juvenis. As maiores capturas (CPUE=11,27 ind./10 m*12 h) e maior riqueza de espécies (S=22) foram registradas no outono, e, em contraponto, menores capturas (CPUE=2,91 ind./10 m*12 h) e menor número de espécies (S=6) ocorreram no inverno. As espécies dominantes e suas frequências variaram sazonalmente. Os comprimentos de malha utilizados são pouco seletivos à espécie dominante, T. marginatus, e a principal problemática envolvendo a pesca com rede de cabo é sua baixa seletividade, pois também ocorre elevada captura de indivíduos juvenis de outras espécies.

Fishing with trammel nets in the Casino Beach, RS, Brazil / A pesca com rede de cabo na praia do Cassino, RS, Brasil

Surf-zone trammel nets is a traditional artisanal fishing activity that take place along the coast of Rio Grande do Sul (RS) state, Brazil. In this study we analyze the seasonal variations in catches of Surf-zone trammel nets at Cassino Beach, RS, and report the list of fish species caught, their size distribution and variations in caught with mesh size. Fishermen were interview in the field soon after they bring the caught to the shore and fish species identified and measured. Net dimensions and mesh size was also inquired. Twenty-four fish species were identified and Trachinotus marginatus (plata pompano), Micropogonias furnieri (whitemouth croaker), Mugil liza (striped mullet), Menticirrhus americanus (kingcroaker) sum-up to 70% of the total catch. The larger abundance (CPUE = 11.27 ind. / 10m * 12h) and higher species richness (S = 22) occurred in the fall, as opposite to winter, were, smaller catches (CPUE = 2.91 ind. / 10m * 12h) and low number of species (S = 6) were reported. The dominant species and their frequencies varied seasonally. The diversity of mesh size used was non selective for the dominate species (T. marginatus). The main problems involving the use of surf-zone trammel nets is their low selectivity, since most of the individuals caught are juveniles of different species.(AU)

A pesca com rede de cabo é uma atividade artesanal de beira de praia que ocorre ao longo de toda a costa do Rio Grande do Sul e na qual se utiliza redes de tresmalhe feiticeiras na zona de arrebentação. O estudo objetivou analisar variações sazonais das capturas pela pesca com rede de cabo na praia do Cassino, RS, identificando as espécies de peixes, estrutura de tamanho dos indivíduos e suas relações com diferentes tamanhos de malha. Foi realizada a identificação das espécies, biometria dos indivíduos capturados e entrevistas semiestruturadas para caracterização das capturas e petrechos de pesca. Vinte e quatro espécies foram identificadas, entre as quais, Trachinotus marginatus (pampo), Micropogonias furnieri (corvina), Mugil liza (tainha), Menticirrhus americanus (papa-terra) que representaram 70% das capturas e ocorreram com elevado número de indivíduos juvenis. As maiores capturas (CPUE=11,27 ind./10 m*12 h) e maior riqueza de espécies (S=22) foram registradas no outono, e, em contraponto, menores capturas (CPUE=2,91 ind./10 m*12 h) e menor número de espécies (S=6) ocorreram no inverno. As espécies dominantes e suas frequências variaram sazonalmente. Os comprimentos de malha utilizados são pouco seletivos à espécie dominante, T. marginatus, e a principal problemática envolvendo a pesca com rede de cabo é sua baixa seletividade, pois também ocorre elevada captura de indivíduos juvenis de outras espécies.(AU)

Assessment of surf zone environmental variables in a southwestern Atlantic sandy beach (Monte Hermoso, Argentina).

The aim of this study was to investigate the temporal dynamics (monthly/tidal) of water temperature, salinity, chlorophyll-a (chlo-a), suspended particulate matter (SPM), particulate organic carbon (POC), and dissolved nutrients in the surf zone of Monte Hermoso sandy beach, Argentina. We also aimed to understand the underlying mechanisms responsible for the observed variability. Sampling was carried out approximately monthly (September 2009-November 2010), and all samples were collected in a fixed station during high and low tide. Water temperature showed a clear seasonal variability (July: 9 °C-December: 26.5 °C) and a thermal amplitude of 17.5 °C. Salinity ranged from 33 to 37, without a pronounced seasonality. SPM (10-223 mg L(-1)) and POC concentrations (399-6445 mg C m(-3)) were high in surf zone waters. Chlo-a (0.05-9.16 µg L(-1)) was low and did not evidence the occurrence of surf diatom accumulations. Dissolved nutrient concentration was quite fluctuating. None of the variables seemed to be affected by tidal stage. The results showed how fluctuating the physico-chemical and biological variables can be in this particular system. The observed variability can be related with local beach conditions but also with regional processes. The study area is highly influenced by a neighbor estuary and as a consequence, could be vulnerable to their seasonal and inter-annual dynamics. All of these characteristics must be considered for further studies and planning of the uses of natural resources and should be taken into account in any environmental monitoring program conducted in a similar beach system.

Asterionellopsis tropicalis (Bacillariophyceae): a new tropical species found in diatom accumulations.

The diatom Asterionellopsis glacialis sensu lato forms high-density patches in the surf zone of some sandy beaches worldwide and was until recently considered a cosmopolitan species. With the recent description of four cryptic species, the identity of specimens found in these accumulations remains uncertain. In this study, diatom patches were sampled from two sandy beaches of the Brazilian coast: one tropical (Futuro Beach, 3° S; 38° W) and one subtropical (Cassino Beach, 32° S; 52° W). Fine structure of frustules and the sequencing of three phylogenetic markers revealed the subtropical strains to be A. guyunusae and the tropical strains to be a new species, here described as Asterionellopsis tropicalis sp. nov. A. tropicalis was differentiated morphologically by the number of striae in 10 µm at the foot pole and head (39-44; 38-45, respectively), from A. lenisilicea (46-55; 46-64), A. maritima (46-51; 46-60), and A. thurstonii (42-58; 55-70). The number of striae at the head region of the valvocopula (10 µm) helped to distinguish A. tropicalis (56-62) from A. guyunusae (61-64), but A. tropicalis was morphologically undistinguishable from A. glacialis. The sequence divergence from other identified Asterionellopsis species was 13%-16% (Cox1), 11%-12% (5.8S + ITS2) and 2%-6% (RbcL), and A. tropicalis formed a distinct monophyletic clade with high support in all analyzed phylogenetic trees (single or multi-locus). This work will aid in the understanding of the ecological and physiological diversity of diatom patches that are key to the trophic webs of sandy beaches.

Longer is not always better: the influence of beach seine net haul distance on fish catchability

The aim of this study was to compare the influence of different haul distances of a codend beach seine on the catchability of fish in a surf zone. Two different surf zone sites (A and B) at the Cassino Beach (Rio Grande do Sul, Brazil) were sampled at three different distances, parallel to the beach (30, 60, and 90 m). Starting 40 m from the beach line, diagonal distances of approximately 50, 70, and 100 m were swept. The total CPUE and CPUA haul distances are compatible with a declining trend in catch rates with increased haul distance at both sites. However, statistically significant differences were observed only for the short distance CPUA (50 m) in relation to the other haul distances at one of the sites sampled. Two fish size groups were observed (TL 40 and > 40 mm), but only small individuals ( 40 mm) captured in the shorter haul distance at site B showed significant differences in CPUA. This result indicates that size structure for hauls at different distances was equal and that smaller individuals determined the pattern of fish abundance. The net performance indicates that a short haul ( 50 m) is the best strategy to reduce net avoidance and fish escape when using this type of sampling gear.

Longer is not always better: the influence of beach seine net haul distance on fish catchability

The aim of this study was to compare the influence of different haul distances of a codend beach seine on the catchability of fish in a surf zone. Two different surf zone sites (A and B) at the Cassino Beach (Rio Grande do Sul, Brazil) were sampled at three different distances, parallel to the beach (30, 60, and 90 m). Starting 40 m from the beach line, diagonal distances of approximately 50, 70, and 100 m were swept. The total CPUE and CPUA haul distances are compatible with a declining trend in catch rates with increased haul distance at both sites. However, statistically significant differences were observed only for the short distance CPUA (50 m) in relation to the other haul distances at one of the sites sampled. Two fish size groups were observed (TL 40 and > 40 mm), but only small individuals ( 40 mm) captured in the shorter haul distance at site B showed significant differences in CPUA. This result indicates that size structure for hauls at different distances was equal and that smaller individuals determined the pattern of fish abundance. The net performance indicates that a short haul ( 50 m) is the best strategy to reduce net avoidance and fish escape when using this type of sampling gear.(AU)

Dieta de juvenis de Trachinotus carolinus (Actinopterygii, Carangidae) em praias arenosas na costa do Rio de Janeiro

We studied the diet of juvenile Trachinotus carolinus (Linnaeus, 1766) in sandy beaches of Sepetiba Bay (Rio de Janeiro, Brazil), between January 2000 and April 2001. We tried to evaluate the trophic plasticity of fish this species along a spatial gradient of wave exposure, seasonality, besides to evaluate ontogenetic changes in the diet. The Index of Relative Importance (IRI) was used to measure the food items, determined by their frequency of occurrence, numbers and weights. The subphylum Crustacea, mainly the order Mysidacea, Decapoda Emerita brasiliensis (Schmitt, 1935) and Cephalochordata, represented by Branchiostoma platae (Fitzinger, 1862) were dominant in the diet. In the most exposed zone (Barra de Guaratiba beach) with predominant sandy substrate, the diet was comprised mainly by Emerita brasiliensis and Cirripedia, this later item common in rocky shores at the beach edge; in the intermediate exposed beach (Muriqui beach), Mysidacea and Branchiostoma platae; in the most protected beach (Itacuruçá beach), Polychaeta, Mysidacea and Branchiostoma platae was predominant. No seasonal change was recorded for the use of Mysidacea, while Branchiostoma platae was the more consumed during the winter, Polychaeta in spring, Cirripedia and Emerita brasiliensis, in summer. Mysidacea was the predominate food in all size classes, while Polychaeta was used predominantly by fish smaller than 20 mm standard length (SL) and Emerita brasiliensis and Cirripedia, were consumed mainly by larger individuals than 40 mm in the most exposed beach only. The success in use of surf zones and sand beaches by this fishes species, it can be partly, due the opportunist trophic strategy that uses a wide variety of available resources on environmental.

Estudamos a dieta dos juvenis de Trachinotus carolinus (Linnaeus, 1766) em praias da Baía de Sepetiba (Rio de Janeiro, Brasil) entre janeiro de 2000 e abril de 2001. Procuramos avaliar a plasticidade trófica de peixes desta espécie ao longo de um gradiente espacial com diferentes níveis de exposição às ondas, sazonalidade, além de avaliar mudanças ontogenéticas na dieta. Os itens alimentares foram analisados através do índice de importância relativa (IIR), determinado pelos valores das frequências de ocorrência, de número e de peso. Os itens de maior importância foram do subfilo Crustacea, ordens Mysidacea, e o representante da ordem Decapoda Emerita brasiliensis (Schmitt, 1935), além de Cefalochordata, representado por Branchiostoma platae (Fitzinger, 1862). Na zona de maior exposição às ondas (praia de Barra de Guaratiba) e com substrato predominantemente arenoso, a dieta foi constituída principalmente por Emerita brasiliensis e Cirripedia, este último presente nos costões rochosos que limitam a praia; na zona de exposição intermediária (praia de Muriqui), houve um predomínio de Mysidacea e Branchiostoma platae; na zona mais protegida (praia de Itacuruçá), os itens de maior abundância foram Polychaeta, Mysidacea e Branchiostoma platae. Sazonalmente não ocorreu variação no uso de Mysidacea, enquanto Branchiostoma platae foi mais consumido durante o inverno, Polychaeta na primavera e Cirripedia e Emerita brasiliensis, no verão. Mysidacea foi o alimento predominante em todas as classes de tamanho, enquanto Polychaeta foi utilizado predominantemente por peixes menores que 20 mm de comprimento padrão e Emerita brasiliensis e Cirripedia foram consumidos principalmente por indivíduos maiores que 40 mm, somente na praia de maior exposição. O sucesso no uso de praias desprotegidas e zonas de arrebentação por esta espécie de peixe pode ser em parte devido à estratégia trófica oportunista, que utiliza uma ampla variedade de recursos disponíveis no ambiente.

Dieta de juvenis de Trachinotus carolinus (Actinopterygii, Carangidae) em praias arenosas na costa do Rio de Janeiro

We studied the diet of juvenile Trachinotus carolinus (Linnaeus, 1766) in sandy beaches of Sepetiba Bay (Rio de Janeiro, Brazil), between January 2000 and April 2001. We tried to evaluate the trophic plasticity of fish this species along a spatial gradient of wave exposure, seasonality, besides to evaluate ontogenetic changes in the diet. The Index of Relative Importance (IRI) was used to measure the food items, determined by their frequency of occurrence, numbers and weights. The subphylum Crustacea, mainly the order Mysidacea, Decapoda Emerita brasiliensis (Schmitt, 1935) and Cephalochordata, represented by Branchiostoma platae (Fitzinger, 1862) were dominant in the diet. In the most exposed zone (Barra de Guaratiba beach) with predominant sandy substrate, the diet was comprised mainly by Emerita brasiliensis and Cirripedia, this later item common in rocky shores at the beach edge; in the intermediate exposed beach (Muriqui beach), Mysidacea and Branchiostoma platae; in the most protected beach (Itacuruçá beach), Polychaeta, Mysidacea and Branchiostoma platae was predominant. No seasonal change was recorded for the use of Mysidacea, while Branchiostoma platae was the more consumed during the winter, Polychaeta in spring, Cirripedia and Emerita brasiliensis, in summer. Mysidacea was the predominate food in all size classes, while Polychaeta was used predominantly by fish smaller than 20 mm standard length (SL) and Emerita brasiliensis and Cirripedia, were consumed mainly by larger individuals than 40 mm in the most exposed beach only. The success in use of surf zones and sand beaches by this fishes species, it can be partly, due the opportunist trophic strategy that uses a wide variety of available resources on environmental.

Estudamos a dieta dos juvenis de Trachinotus carolinus (Linnaeus, 1766) em praias da Baía de Sepetiba (Rio de Janeiro, Brasil) entre janeiro de 2000 e abril de 2001. Procuramos avaliar a plasticidade trófica de peixes desta espécie ao longo de um gradiente espacial com diferentes níveis de exposição às ondas, sazonalidade, além de avaliar mudanças ontogenéticas na dieta. Os itens alimentares foram analisados através do índice de importância relativa (IIR), determinado pelos valores das frequências de ocorrência, de número e de peso. Os itens de maior importância foram do subfilo Crustacea, ordens Mysidacea, e o representante da ordem Decapoda Emerita brasiliensis (Schmitt, 1935), além de Cefalochordata, representado por Branchiostoma platae (Fitzinger, 1862). Na zona de maior exposição às ondas (praia de Barra de Guaratiba) e com substrato predominantemente arenoso, a dieta foi constituída principalmente por Emerita brasiliensis e Cirripedia, este último presente nos costões rochosos que limitam a praia; na zona de exposição intermediária (praia de Muriqui), houve um predomínio de Mysidacea e Branchiostoma platae; na zona mais protegida (praia de Itacuruçá), os itens de maior abundância foram Polychaeta, Mysidacea e Branchiostoma platae. Sazonalmente não ocorreu variação no uso de Mysidacea, enquanto Branchiostoma platae foi mais consumido durante o inverno, Polychaeta na primavera e Cirripedia e Emerita brasiliensis, no verão. Mysidacea foi o alimento predominante em todas as classes de tamanho, enquanto Polychaeta foi utilizado predominantemente por peixes menores que 20 mm de comprimento padrão e Emerita brasiliensis e Cirripedia foram consumidos principalmente por indivíduos maiores que 40 mm, somente na praia de maior exposição. O sucesso no uso de praias desprotegidas e zonas de arrebentação por esta espécie de peixe pode ser em parte devido à estratégia trófica oportunista, que utiliza uma ampla variedade de recursos disponíveis no ambiente.

DIVERSITY AND MORPHOLOGY OF SKELETONEMA SPECIES IN SOUTHERN BRAZIL, SOUTHWESTERN ATLANTIC OCEAN(1).

We examined the morphology of Skeletonema species occurring in coastal waters of southern Brazil, on the basis of LM, SEM, and TEM analyses of six isolated strains and of 13 field samples from the Patos Lagoon estuary and the adjacent Cassino Beach. We concluded that the genus Skeletonema is highly diverse in coastal waters of southern Brazil, with the occurrence of four confirmed species: S. costatum, S. pseudocostatum, S. potamos, and S. tropicum. In addition, EM details must still be provided for S. menzelii, and genetic studies should be conducted to confirm the identity of S. cf. grethae and S. subsalsum. The high diversity in this geographic area can be attributed to the proximity of the Subtropical Convergence and to the freshwater ecosystems of Patos Lagoon and La Plata River that favor the presence of warm-, cold-, and brackish-water species.

Variação temporal do zooplâncton da Praia de Tramandaí, Rio Grande do Sul, com ênfase em Copepoda

The temporal variability of density, species composition, biomass and diversity of the surf zone zooplankton from Tramandaí Beach, RS, Brazil, was studied between August 2005 and August 2006. Samples were taken forthnightly using a zooplankton net of 150 cm total length, 50 cm mouth diameter and 300 m nylon mesh size. Data on clorofila-a, wind direction, longshore current, salinity, air and water temperature were taken as well. Copepoda presented the highest species diversity, being Temora turbinata (Dana, 1849) the species with higher relative abundance and frequency of occurrence. Other Copepoda species were also numerically important, such as Acartia tonsa (Dana, 1849), Subeucalanus pileatus (Glesbrecht, 1888) and Ctenocalanus vanus (Glesbrecht, 1888). The Mysidacea Metamysidopsis elongata atlantica (Bascescu, 1968) presented frequency of 58.33% and relative abundance of 44%. The peak of mesozooplanktonic biomass (96 mg.m-3) was recorded in September/2005, corresponding to the maximum density value presented for this species (3,535 org.m-3). Information about zooplankton of this region is scarce and the results of this study will provide a base for the knowledge about the biological processes occurring in the surf zone of Tramandaí Beach.

Com o objetivo de conhecer a variação temporal da composição, abundância, diversidade e biomassa do zooplâncton da zona de arrebentação da Praia de Tramandaí, Rio Grande do Sul, amostragens quinzenais foram realizadas entre agosto de 2005 e agosto de 2006. Os arrastos foram efetuados com rede cilindro-cônica com 150 cm de comprimento, 50 cm de diâmetro de boca e malha de 300 µm. Dados de clorofila-a, direção do vento, corrente de deriva litorânea, salinidade, temperatura do ar e da água também foram obtidos. O grupo dos Copepoda foi responsável pela maior diversidade de espécies, sendo que Temora turbinata (Dana, 1849) apresentou maior abundância relativa e freqüência de ocorrência. Outras espécies de Copepoda também foram importantes numericamente como Acartia tonsa (Dana, 1849), Subeucalanus pileatus (Glesbrecht, 1888) e Ctenocalanus vanus (Glesbrecht, 1888). O Mysidacea Metamysidopsis elongata atlantica (Bascescu, 1968) apresentou freqüência de 58,33% e abundância relativa de 44%, sendo o pico de biomassa de mesozooplâncton (96 mg.m-3) registrado em setembro de 2005 correspondente ao máximo valor de densidade apresentado pela espécie (3.535 org.m-3). Informações sobre o zooplâncton desta região são muito escassos e os dados levantados servirão de base para o conhecimento dos processos biológicos que ocorrem na coluna d'água da Praia de Tramandaí.

Variação temporal do zooplâncton da Praia de Tramandaí, Rio Grande do Sul, com ênfase em Copepoda

The temporal variability of density, species composition, biomass and diversity of the surf zone zooplankton from Tramandaí Beach, RS, Brazil, was studied between August 2005 and August 2006. Samples were taken forthnightly using a zooplankton net of 150 cm total length, 50 cm mouth diameter and 300 m nylon mesh size. Data on clorofila-a, wind direction, longshore current, salinity, air and water temperature were taken as well. Copepoda presented the highest species diversity, being Temora turbinata (Dana, 1849) the species with higher relative abundance and frequency of occurrence. Other Copepoda species were also numerically important, such as Acartia tonsa (Dana, 1849), Subeucalanus pileatus (Glesbrecht, 1888) and Ctenocalanus vanus (Glesbrecht, 1888). The Mysidacea Metamysidopsis elongata atlantica (Bascescu, 1968) presented frequency of 58.33% and relative abundance of 44%. The peak of mesozooplanktonic biomass (96 mg.m-3) was recorded in September/2005, corresponding to the maximum density value presented for this species (3,535 org.m-3). Information about zooplankton of this region is scarce and the results of this study will provide a base for the knowledge about the biological processes occurring in the surf zone of Tramandaí Beach.

Com o objetivo de conhecer a variação temporal da composição, abundância, diversidade e biomassa do zooplâncton da zona de arrebentação da Praia de Tramandaí, Rio Grande do Sul, amostragens quinzenais foram realizadas entre agosto de 2005 e agosto de 2006. Os arrastos foram efetuados com rede cilindro-cônica com 150 cm de comprimento, 50 cm de diâmetro de boca e malha de 300 µm. Dados de clorofila-a, direção do vento, corrente de deriva litorânea, salinidade, temperatura do ar e da água também foram obtidos. O grupo dos Copepoda foi responsável pela maior diversidade de espécies, sendo que Temora turbinata (Dana, 1849) apresentou maior abundância relativa e freqüência de ocorrência. Outras espécies de Copepoda também foram importantes numericamente como Acartia tonsa (Dana, 1849), Subeucalanus pileatus (Glesbrecht, 1888) e Ctenocalanus vanus (Glesbrecht, 1888). O Mysidacea Metamysidopsis elongata atlantica (Bascescu, 1968) apresentou freqüência de 58,33% e abundância relativa de 44%, sendo o pico de biomassa de mesozooplâncton (96 mg.m-3) registrado em setembro de 2005 correspondente ao máximo valor de densidade apresentado pela espécie (3.535 org.m-3). Informações sobre o zooplâncton desta região são muito escassos e os dados levantados servirão de base para o conhecimento dos processos biológicos que ocorrem na coluna d'água da Praia de Tramandaí.

Efeito do grau de exposição às ondas sobre a comunidade de peixes juvenis em praias arenosas do Município do Rio de Janeiro, Brasil / Effect of the wave exposure gradient on juvenile fish community in sandy beaches of the Rio de Janeiro City, Brazil

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 por cento do número total de indivíduos e 61 por cento da biomassa total. As espécies de maior participação na biomassa, representando 81 por cento do peso total, foram Harengula clupeola (36 por cento), Orthopristis ruber (14 por cento), Mugil liza (10 por cento), Trachinotus goodei (8 por cento), Trachinotus carolinus (7 por cento) e Umbrina coroides (6 por cento). Três espécies apresentaram maior abundância relativa, tendo cada uma, contribuído acima de 10 por cento 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 indicadores apresentou diferença significativa (p > 0,05). O grau de exposição às ondas foi confirmado como um fator primário na estruturação da comunidade de peixes, com os locais mais abrigados provavelmente associados à maior disponibilidade de organismos planctônicos, menores turbulências e maior estabilidade do substrato.

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 percent of the total fish number and 61 percent of the total biomass. The following species amounted to 81 percent of the total weight were: Harengula clupeola (36 percent), Orthopristis ruber (14 percent), Mugil liza (10 percent), Trachinotus goodei (8 percent), Trachinotus carolinus (7 percent) and Umbrina coroides (6 percent). Three species showed the highest relative abundance, contributing each one more than 10 percent 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.