Comportamento alimentar de paralarvas do polvo Octopus vulgaris Tipo II (Cuvier, 1797) alimentadas com artêmia enriquecida com microalgas e suplementada com DHA / Feeding behavior of octopus Octopus vulgaris Type II (Cuvier, 1797) paralarvae fed on Artemia enriched with microalgae and supplemented with DHA

The inexistence of nutritionally adequate diets in paralarval rearing is the main bottleneck for commercial production of the common octopus Octopus cf. vulgaris. We report the feeding behavior of O. vulgaris Type II paralarvae fed on Artemia sp (0.1 individual. mL-1) nauplii enriched with microalgae Isocrysis galbana and Pavlova lutheri microalgae from 0 to 7 Day After Hatching (DAH).; metanauplii enriched with microalgae and DHA SELCO® lipid emulsion from the 8 DAH. The paralarvae showed active swimming and predation by the 14 DAH, feeding in the most superficial portion of the water column. From the 15 DAH, the paralarvae remained near the bottom and there a decrease in the consumption of artemia was observed. The mortality observed from the 18 DAH and mass mortality of paralarvae on 20 DAH can be attributed mainly to the nutritional composition of the diet. Studies analyzing the biochemical composition and ontogeny of the digestive system during the early life stages should shed some light on the running for an appropriate feeding protocol to the paralarval rearing.(AU)

Comportamento alimentar de paralarvas do polvo Octopus vulgaris Tipo II (Cuvier, 1797) alimentadas com artêmia enriquecida com microalgas e suplementada com DHA / Feeding behavior of octopus Octopus vulgaris Type II (Cuvier, 1797) paralarvae fed on Artemia enriched with microalgae and supplemented with DHA

The inexistence of nutritionally adequate diets in paralarval rearing is the main bottleneck for commercial production of the common octopus Octopus cf. vulgaris. We report the feeding behavior of O. vulgaris Type II paralarvae fed on Artemia sp (0.1 individual. mL-1) nauplii enriched with microalgae Isocrysis galbana and Pavlova lutheri microalgae from 0 to 7 Day After Hatching (DAH).; metanauplii enriched with microalgae and DHA SELCO® lipid emulsion from the 8 DAH. The paralarvae showed active swimming and predation by the 14 DAH, feeding in the most superficial portion of the water column. From the 15 DAH, the paralarvae remained near the bottom and there a decrease in the consumption of artemia was observed. The mortality observed from the 18 DAH and mass mortality of paralarvae on 20 DAH can be attributed mainly to the nutritional composition of the diet. Studies analyzing the biochemical composition and ontogeny of the digestive system during the early life stages should shed some light on the running for an appropriate feeding protocol to the paralarval rearing.(AU)

The reproductive cycle of the oyster Crassostrea gasar / Ciclo reprodutivo da ostra Crassostrea gasar

The purpose of this study was to analyze the reproductive cycle of the oyster Crassostrea gasar (= C. brasiliana) in the field and the laboratory. The reproductive cycle of the animals was evaluated in the field at Sambaqui Beach, Florianópolis, SC (27° 29′18″ S and 48° 32′12″ W) from May 2008 through November 2009. In July, the animals were in the resting stage. The early growth stage began in August and was followed by the late growth stage in October. In November and December, the oysters began to enter the mature stage. Females in spawning condition were predominant during these months. The stages of the reproductive cycle were positively associated with temperature (r=0.77, P<0.01) and negatively associated with salinity (r=−0.56, P=0.042). These findings demonstrated that increased temperature and reduced salinity influence the reproductive development of Crassostrea gasar. The condition index (CI) of the animals was also associated with the seawater temperature. The highest values of the condition index were observed during the months when the temperature of the seawater was gradually increasing. A laboratory experiment was performed to test the effect of salinity on the reproductive cycle of the oysters. The experiment was conducted in standardized tanks. The animals were conditioned using two salinities (24‰ and 34‰). The salinity regime influenced the development of the gonadal tissue of the oysters. A salinity of 24‰ produced greater reproductive development.(AU)

O presente estudo teve como objetivo avaliar o ciclo reprodutivo da ostra Crassostrea gasar, em campo e em laboratório. O estádio de desenvolvimento do ciclo reprodutivo dos animais foi acompanhado na Praia do Sambaqui/Florianópolis/SC (27°29′18″S e 48°32′12″W) entre maio de 2008 e novembro de 2009. No mês de julho os animais encontravam-se no estádio de repouso e entre os meses de agosto a outubro, as ostras seguiram nos estádios de pré-maturação e maturação. Entre os meses de novembro e dezembro, as ostras começaram a ser encontradas no estádio maturo, havendo predominância de fêmeas aptas a eliminação de gametas. Houve associação positiva (r=0,77; P<0,01) entre o estádio de desenvolvimento do ciclo reprodutivo das ostras e a temperatura, bem como associação negativa com a salinidade (r=−0,56; P=0,042), demonstrando que tanto o aumento da temperatura como a redução da salinidade são fatores ambientais que influenciam no desenvolvimento reprodutivo das ostras dessa espécie. O índice de condição (IC) dos animais, também teve relação com a temperatura da água do mar, sendo os maiores índices observados nos meses em que a temperatura da água do mar teve aumento gradativo. Também foi realizado um experimento em laboratório visando testar o efeito da salinidade da água sobre o desenvolvimento reprodutivo das ostras. Para tanto, os animais foram condicionados em tanques padronizados e testaram-se duas salinidades (24‰ e 34‰). Observou-se que o regime de salinidade influenciou o desenvolvimento do tecido gonádico das ostras, sendo que a salinidade de 24‰ permitiu aos animais maior desenvolvimento reprodutivo.(AU)