The reproductive cycle of the oyster Crassostrea gasar

Abstract

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.Keywords: oysters, reproductive cycle, Crassostrea gasar, conditioning. Ciclo reprodutivo da ostra Crassostrea gasar ResumoO 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 encontravamse 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 3...

Epizootiology of Perkinsus sp. inCrassostrea gasar oysters in polyculture with shrimps in northeastern Brazil

“…infection, both conditions did not occur together, which might have contributed to the lack of mortality events during the growing stage of oysters. To date, massive mortality events have not been reported in cultured oysters from NE Brazil (Farmers, personal communication;SILVA et al, 2013SILVA et al, , 2014QUEIROGA et al, 2015).…”

“…In contrast, P. marinus was detected in two oyster species, C. rhizophorae and C. gasar from Paraíba state with high prevalence (71% to 100%) and moderate mean intensities (SILVA et al, 2013;QUEIROGA et al, 2015). Perkinsus marinus was also detected in C. gasar from Sergipe state, although the prevalences in oysters varied seasonally (7% in July to 80% in December) and was higher in cultured oysters (56%) than wild oysters (35%) (SILVA et al, 2014). Perkinsus olseni was also identified in the oyster C. gasar from Sergipe.…”

“…The expected product size was 560 bp. Samples of DNA from C. gasar (SILVA et al, 2014), C. rhizophorae (SILVA et al, 2013) and C. gigas (provided by the Laboratory of Immunology Applied to Aquaculture, UFSC), were used as controls. The PCR amplification products were stained with Blue Green Loading Dye I (LGC Biotecnologia) and resolved via electrophoresis in 1% agarose gels.…”

“…However, some efforts have been made by research institutions to understand certain biological aspects of C. gasar that may be useful in the production process (LOPES et al, 2013;RAMOS et al, 2014;SILVEIRA et al, 2011;GOMES et al, 2014).…”

“…Perkinsus olseni was also identified in the oyster C. gasar from Sergipe. However, it seems that this protozoan species occurs with a very low prevalence because few nucleotide sequences are obtained from host tissues (SILVA et al, 2014). In Bahia state, an unidentified Perkinsus sp.…”