A distribuição e abundância da raia elétrica Narcine brasiliensis foi analisada com base em 416 lances de arrasto de fundo realizados entre as profundidades de 10- 100 m ao longo da costa do Rio Grande do Sul, em 1980-1984 e 2005. A espécie ocorreu prioritariamente em águas com temperatura de fundo entre 20 e 25ºC. A densidade de N. brasiliensis foi maior durante o verão e outono e entre as profundidades de 10 e 20 m. O padrão sazonal de densidade da espécie nas águas costeiras rasas do Rio Grande do Sul reflete uma migração no sentido norte-sul condicionada pelo avanço das águas quentes e de alta salinidade da Água Tropical da Corrente do Brasil em direção ao sul durante o verão. A redução sazonal da temperatura da água e o avanço da Água Costeira, de baixa salinidade, determinam a migração da espécie em direção ao norte no inverno. O gradiente latitudinal de densidade de N. brasiliensis esteve relacionado com o gradiente latitudinal de salinidade das águas de fundo decorrente da descarga de água doce oriunda da Lagoa dos Patos, que estabelece uma barreira física para a ocorrência da espécie ao sul da cidade de Rio Grande.

The distribution and abundance of the lesser electric ray, Narcine brasiliensis, was assessed based on bottom-trawl survey data collected off the coast of Rio Grande do Sul, southern Brazil. Between 1980 and 1984 and in 2005, 416 bottom trawl hauls were carried out at depths of 10-100 m. Narcine brasiliensis occurred mainly in waters with bottom temperature between 20 and 25ºC. Density of the species was higher between the depths of 10 and 20 m, during the summer and autumn. The seasonal pattern of N. brasiliensis in the shallow coastal water of Rio Grande do Sul reflects a southward migration in summer. This is conditioned by the southward advance of warmer and high-salinity Tropical Water of the Brazil Current In winter, the return or northward migration is a response to seasonal cooling of the coastal waters and to the northward advance of cold Coastal Water of lower salinity. The latitudinal gradient in density of N. brasiliensis was related to the latitudinal gradient in salinity of the bottom waters. This was caused by the freshwater runoff from the Patos Lagoon establishing a physical barrier to the occurrence of the species farther south than the city of Rio Grande.

Um total de 425 estômagos de tubarão-toninha (Carcharhinus signatus) e 98 estômagos de tubarão-martelo-entalhado (Sphyrna lewini), oriundos da pesca de espinhel e pesca com rede de emalhe nas adjacências dos bancos oceânicos do nordeste do Brasil, foi analisado entre 1992 e 1999. Ambas as espécies predam sobre peixes bento-pelágicos e recifais, cefalópodes migradores, e crustáceos de águas profundas, apresentando nichos alimentares similares (Índice de Schoener T=0.75). A alta riqueza de presas nas dietas deve ser um reflexo de que as teias alimentares para estas espécies são consideravelmente longas nessa região. Devido à concentração alimentar de ambos predadores nos bancos oceânicos, a pescaria intensa deve ser monitorada para evitar depleções locais.

A total of 425 stomachs of night shark (Carcharhinus signatus), and 98 stomachs of scalloped hammerhead shark (Sphyrna lewini), from longline and surface gillneters near seamounts off northeastern Brazil, were analysed between 1992 and 1999. Both predators prey upon reef and benthopelagic fishes, migrant cephalopods and deep water crustaceans, showing similar feeding niches (Schoener Index T=0.75). The great prey richness of the diets may reflect the fact that the marine food web for these species is very extensive in this region. Due to the concentration for feeding of both predators in the seamounts, intense fisheries should be monitored to avoid localised depletions.

Censuses of the Neotropic Cormorant (Phalacrocorax brasilianus) were carried out at a power tower near the mouth of Lagoa dos Patos estuary, southern Brazil, from November 2001 to October 2002. At this major roosting site, a total of 309 counts over 47 days of census were performed to estimate monthly variation in the abundance of the Neotropic Cormorant. The highest abundance occurred in January (1390 birds), and the lowest in May (117 birds). The tower was a roosting site for cormorants at night, which arrived around 15:30 h onward, with numbers increasing near dusk. Birds preferentially used the lower levels of the tower (including the concrete base and levels 1 and 2) throughout the year and this preference could be partially due to strong winds in the area. Migrating cormorants arrived at the estuary in winter and spring, increasing throughout the summer and severely decreasing in autumn months, when they probably moved to inland breeding grounds.

Se realizaron censos de Biguá (Phalacrocorax brasilianus) en una torre de transmisión de energía eléctrica cerca de la barra de la laguna dos Patos, en el sur de Brasil, entre noviembre de 2001 y octubre de 2002. Se realizaron un total de 309 conteos en 47 días de censos para estimar la variación mensual en la abundancia del Biguá. La mayor abundancia se observó en enero (1390 aves) y la menor en mayo (117 aves). La torre fue un importante sitio de descanso nocturno al cual las aves llegaban alrededor de las 15:30 h, aumentando el número de aves cerca del atardecer. Las aves utilizaron preferentemente los niveles inferiores de la torre (la base de hormigón y los niveles 1 y 2) durante todo el año y esta preferencia podría estar relacionada con los fuertes vientos en el área. Los biguaes migrantes llegaron al estuario en invierno y primavera, aumentaron sus números durante el verano y mostraron una gran disminución en el otoño, cuando probablemente se muevan hacia áreas reproductivas en el interior.

For nine days, the number of sally lightfoot crabs (Grapsus grapsus) in a 300 m² area within the brown booby (Sula leucogaster) colony and the activity of each crab were recorded in the morning (5:30-7:30 h), at midday (11:30-13:30 h), and in the afternoon (15:30-17:30 h). The average number of individuals was 80.2 ±15.5 (59-111) in the morning, 3.1 ± 2.3 (0-7) at midday, and 65.3 ± 15 (49-92) in the afternoon. A total of 1338 activity records were made, with the crabs standing still or walking in 844 records and handling material or feeding in 494 records. In the latter records, 53% of the crabs were handling detritus (pieces of dry bird excrement and sediment), 12.2% were handling feathers, 12.8% were feeding on regurgitated fish, 8.9% were feeding on dead Sula leucogaster, 8.1% were feeding on crab, 4.7% were feeding on material adhered to egg shells, and 0.6% were feeding on live nestlings of S. leucogaster. The low frequency of crabs in the colony around noon shows that the crabs avoid insolation, hiding in shady places and tidal pools. In the Sao Pedro and Sao Paulo Archipelago, the presence of S. leucogaster represents an important food source for G. grapsus. This crab plays the role of a cleaner in the S. leucogaster colony, consuming food remains, broken eggs, and dead birds

Durante nueve días se registró el número de cangrejos costeros (Grapsus grapsus) en una área de 300 m²dentro de la colonia de piquero café (Sula leucogaster) y la actividad de cada uno de los individuos durante la mañana (5:30-7:30 h), mediodía (11:30-13:30 h) y tarde (15:30-17:30 h). La media de individuos en la mañana fue 80,2 ± 15,5 (59-111), en el mediodía 3,1 ± 2,3 (0-7) y en la tarde 65,3 ± 15 (49-92). Del total de 1.338 registros de comportamiento, 844 fueron de cangrejos detenidos o caminando y 494 manipulando algún material o alimento. De éstos, 53% fueron de manipulación de detrito (excremento seco de ave y sedimento); 12,2% de manipulación de plumas; 12,8% alimentándose de peces regurgitados; 8,9% de un Sula muerto; 8,1% de cangrejo; 4,7% de material adherido a las cascaras de huevos y 0,6% de cría de Sula viva. La baja frecuencia de los cangrejos en la colonia durante el mediodía es una evidencia que los mismos se protegen de la insolación, permaneciendo en la sombra y en pozas de marea. En el archipiélago de Sao Pedro y Sao Paulo la presencia de S. leucogaster representa una importante fuente de alimentación para G. grapsus, que desempeña un papel de limpiador en la colonia de esta ave, consumiendo restos de comida, huevos quebrados y aves muertas

Foram capturados 459 exemplares de Atlantoraja cyclophora na costa do Rio Grande do Sul entre as latitudes 30º40'S e 34º30'S, em dois cruzeiros realizados respectivamente no inverno de 2001 e no verão/outono de 2002, com rede de arrasto de fundo, operada entre 100 e 600 m de profundidade. A espécie ocorreu nas profundidades de 100 a 300 m, não havendo diferenças significativas na freqüência de ocorrência nem na abundância (CPUE; kg/hora) entre latitudes, estratos de profundidade em ambas estações do ano. A proporção sexual não foi significativamente diferente de 1:1 em todas as profundidades. Na área estudada a temperatura variou entre 10,0 ºC e 17,6 ºC e a salinidade entre 35,2 e 36,0 ppm. Não houve correlação entre CPUE e profundidade, temperatura e salinidade. O comprimento total médio das fêmeas (53,2 cm) foi significantemente maior que o dos machos (50,9 cm). Não houve diferença no comprimento total médio entre estações do ano, mas sim entre profundidades, sendo significantemente maiores nos estratos de 100 a 200 m. As distribuições de freqüências de comprimento total foram assimétricas, indicando ausência ou escassez de indivíduos juvenis.

A total of 459 individuals of Atlantoraja cyclophora were captured along the Rio Grande do Sul coast between latitudes 30º40'S and 34º30'S. Two surveys were performed, in the winter 2001 and in the summer/autumn 2002, using bottom-trawl between the depths of 100 and 600 m. This species occurred between 100 and 300 m deep, without significant differences in the frequency of occurrence and abundance (CPUE; kg/hour) between latitudes, depth and seasons. The sex ratio was not significantly different from 1:1 in all depths. In the study area, temperature ranged between 10.0 ºC and 17.6 ºC and salinity between 35.2 e 36.0 ppm. There was no correlation between CPUE and depth, temperature and salinity. Mean total length of females (53.2 cm) was significantly larger than males (50.9 cm). No differences were detected in mean total length between seasons, but mean total length was significantly larger in depths of 100 m and 200 m. The distribution of the frequencies of total length was asymmetric, indicating rareness or lack of juveniles in the samples.