Abstract This study investigated the temporal abundance, periods of reproduction and recruitment, gonad sexual maturity, and population structure of the swimming crab Achelous spinimanus (Latreille, 1819) in Macaé, a region of the Brazilian coast affected by upwelling events. The samples were collected monthly during one year. The crabs were counted, sexed and measured for maximum carapace width (MCW). Four developmental stages were described in males and females. Environmental variables as temperature, salinity, organic matter and Phi were measured. A Principal Components Analysis indicated that environmental variables were strongly correlated with seasons, affecting the abundance of this species, which was high during summer and autumn. The periods of reproduction and recruitment were also seasonal, with a peak of females with developed gonads and ovigerous females during autumn and immatures during summer and autumn. Males and females did not differ in size at gonad sexual maturity, estimated at 39.9 and 42.9 mm MCW, respectively. The environmental conditions in this upwelling region may have induced this population of A. spinimanus to show different characteristics and behaviors from other populations on the Brazilian coast, since alterations linked to the periods of reproduction and recruitment, as well as the population structure and distribution, may reveal different survival strategies of the species.

The spatial and seasonal distribution of different demographic groups of the swimming crab Callinectes ornatus was analyzed with respect to its population biology in three bays (Ubatumirim, Ubatuba, and Mar Virado) in southeastern Brazil. In each bay, monthly sampling was performed during two years along six transects, established at 5, 10, 15, and 20 m depth (parallel to the beach line), in a wave-sheltered area (7.5 m depth), and at an exposed site (10 m depth). Total abundance of crabs was similar among the bays. The presence of immature individuals, adult females, and breeding females was positively correlated with the bottom and surface temperatures, whereas adult males showed an opposite trend with respect to these factors. Immature and smaller individuals were most abundant along the sheltered and shallower transects. Males were more abundant along the shallower transects, and females at 15 and 20 m. This study revealed that different demographic groups occupy the habitat in different ways, according to local features. In general, southeastern Brazil offers a range of conditions that favor reproduction and consequently the maintenance and growth of the local population of C. ornatus, contributing to the relatively high abundance of the species in this coastal area.

Se analizó la distribución espacial y temporal de distintos grupos demográficos del cangrejo nadador Callinectes ornatus en cuanto a su biologia poblacional en tres bahias (Ubatumirim, Ubatuba y Mar Virado) en el sureste de Brasil. En cada bahia se realizaron muestreos mensuales durante dos años en seis transectos, establecidos a 5, 10, 15 y 20 m de profundidad (paralelo a la linea de costa), en una zona protegida del oleaje (7.5 m de profundidad) y en un sitio expuesto al oleaje (10 m de profundidad). La abundancia total de cangrejos fue similar entre bahias. Se observó una correlación positiva entre la presencia de individuos inmaduros, hembras adultas y hembras ovigeras con la temperatura del fondo y superficial, mientras que los machos adultos mostraron una tendencia opuesta con respecto a estos factores. La mayor abundancia de individuos inmaduros y pequeños fue detectada en los transectos protegidos y menos profundos. Los machos fueron más abundantes en los transectos menos profundos, y las hembras a 15 y 20 m de profundidad. Este estudio reveló que los diferentes grupos demográficos ocupan el hábitat de diferentes maneras, de acuerdo con las caracteristicas locales. En general, el sureste de Brasil ofrece diferentes condiciones que favorecen la reproducción y consecuentemente la continuidad y el crecimiento de la población local de C. ornatus, contribuyendo a la relativamente alta abundancia de la especie en esta zona costera.

The evaluation of population characteristics, particularly those of endemic species, aids in population preservation and management. Hermit crabs present an innate behavior of occupying shells, which tends to individual needs and limits their distribution. This study characterized the pattern of occupation of gastropod shells by the hermit Loxopagurus loxochelis in three bays of the southwestern coast of Brazil. Monthly collections were made from January/1998 to December/1999 in the bays Ubatumirim (UBM), Ubatuba (UBA) and Mar Virado (MV) with a shrimping boat. Overall, ten species of gastropod shells were occupied by L. loxochelis. The shell of Olivancillaria urceus represented 66.8% of those occupied. Morphometric relationships demonstrated a differential occupation of the more abundant shells among demographic groups, where most of the males occupied O. urceus, non-ovigerous females occupied O. urceus and Buccinanops cochlidium, and ovigerous females occupied B. cochlidium and Stramonita haemastoma. Most of the individuals occupied the more abundant shells, considered adequate for the morphology of this hermit crab species. Thus, the studied bays seem to be stable and propitious environments for population perpetuation and the settlement of new individuals.

Com a finalidade de avaliar o efeito de antibióticos e NaCl sobre o comportamento e a sobrevivência de jundiá, Rhamdia quelen, infestados por Ichthyophthirius multifiliis e infectados com Aeromonas hydrophila, juvenis foram tratados com cloranfenicol, cloranfenicol + sal, oxitetraciclina, oxitetraciclina + sal e apenas água (controle). A sobrevivência dos peixes dos tratamentos com cloranfenicol + sal e oxitetraciclina + sal foi significativamente mais elevada que nos demais tratamentos. O tratamento com cloranfenicol apresentou sobrevivência mais elevada que a do tratamento com oxitetraciclina e ambos tiveram sobrevivência significativamente maior que o controle. A atividade natatória foi maior nos peixes tratados com antibióticos e sal do que nos do controle. A combinação dos antibióticos com sal se mostrou mais eficaz no tratamento de jundiás infectados com A. hydrophila e infestados com I. multifiliis, mas, como o uso de cloranfenicol é proibido no Brasil, a oxitetraciclina com sal parece ser a melhor opção de tratamento.

In order to evaluate the use of antibiotics and NaCl on the behavior and survival of silver catfish, Rhamdia quelen, infested by Ichthyophthirius multifiliis and infected with Aeromonas hydrophila, juveniles were treated with chloramphenicol, chloramphenicol + salt, oxytetracycline, oxytetracycline + salt and water alone (control). Fish survival in the treatments with chloramphenicol + salt and oxytetracycline + salt was significantly higher than in the other treatments. The treatment with chloramphenicol presented higher survival than the treatment with oxytetracycline and both showed significantly higher survival than control. Swimming activity was higher in the fish treated with antibiotics and salt compared to control fish. A combination of the studied antibiotics plus salt is more effective to treat both A. hydrophila infection and I. multifiliis infestation in silver catfish, but since the use of chloramphenicol is not allowed in Brazil, oxytetracycline plus salt seems to be the best treatment option.

O presente experimento foi realizado no Laboratório de Aqüicultura da Universidade Estadual de Maringá com o objetivo de avaliar o desempenho e a sobrevivência de alevinos de Leporinus macrocephalus alojados em aquários de vidro com capacidade para 12L, com ou sem refúgios artificiais de diferentes colorações. Foram utilizados 240 alevinos com peso inicial de 0,20 ± 0,06g por um período de 28 dias. Os animais foram distribuídos em um delineamento inteiramente casualizado com seis tratamentos (sem refúgio e com refúgios de cor verde, vermelha, azul, marrom e branca) e quatro repetições. As variáveis analisadas foram peso, comprimento total, sobrevivência, fator de condição e uniformidade do lote. Ao fim do experimento, verificou-se que as variáveis peso, comprimento e fator de condição não diferiram entre os tratamentos com e sem refúgio. Houve maior índice de sobrevivência com a não utilização de refúgio e com refúgios de cor vermelha e verde (P < 0,05) do que quando utilizado o de cor azul. O emprego de refúgios de cor branca proporcionou lotes mais uniformes (P < 0,05) do que os refúgios de cor marrom e verde. Portanto, ao se utilizarem refúgios coloridos no cultivo de piavuçu, recomenda-se preferencialmente as cores brancas e vermelhas, cujos resultados foram satisfatórios e semelhantes ao tratamento sem refúgio.

Weight, length and survival of Leporinus macrocephalus fryes, grown in differently colored artificial havens, were evaluated at the Aquaculture Lab of the Universidade Estadual de Maringá. The experiment was done during 28 days with 240 piavuçu (Leporinus macrocephalus) fryes with initial weight of 0.20±0.06g. The animals were distributed in a entirely randomized design with six treatments (without and green, red, blue, brown and white havens) and four repetitions in 12L-glass aquaria. Final weight, total length, condition factor and uniformity were the analized variables. At the end of the experimental period, weight, lenght and condition factor were not affected by the treatment without or with haven color. Higher survival was observed in the treatments without haven and those with red and green havens (P<0.05) than in those with blue haven. The use of white haven provided more uniform lots (P<0.05) than brown and green havens. It is recomended the use of white or red havens, or no haven for the growth of Leporinus macricephalus fryes.