肾上腺素对岩牡蛎幼虫变态的诱导

为了得到壳型规则、大小均一的单体牡蛎,本研究采用肾上腺素对岩牡蛎单体苗种生产的诱导条件进行研究,阐明了岩牡蛎单体苗种的最适诱导浓度、诱导时间和诱导密度。结果显示,肾上腺素能显著诱导岩牡蛎幼虫的不固着变态,最适诱导浓度为5×10–5 mol/L,最适诱导时间为1 h,提高诱导浓度和延长诱导时间导致岩牡蛎幼虫的不固着变态率、稚贝壳高和存活率显著降低;肾上腺素对低于8个/mL幼虫密度的诱导效果差异不显著,但稚贝壳高和存活率在8个/mL的培育密度下显著低于0.5～4个/mL,研究表明利用肾上腺素诱导岩牡蛎单体时,可大批量处理眼点幼虫,但稚贝充气培养的最适培养密度应不高于4个/mL。

The induction of metamorphosis in Iwagaki oyster (Crassostrea nippona)

The Iwagaki oyster Crassostrea nippona, is a large sessile oyster inhabiting intertidal hard grounds and reefs along the coast of East Asian. Because of its unique flavor, delicious taste and edibility during summer when other oyster species are unavailable, C. nippona is highly valued and has a broad market prospect. To obtain cultchless oyster with a regular shell shape and uniform size, epinephrine (EPI) was applied to C. nippona eye-spot larvae to induce cultchless metamorphosis. To determine optimum levels for C. nippona, the effect of EPI concentration, exposure time to EPI, and larval density were examined. The results demonstrate that EPI can significantly facilitate larval metamorphosis. 0.05 mmol/L and 1 h treatment were the optimum for single oyster seed production, and shell height and survival rates of cultchless spats showed a curve of descending with increasing EPI concentration and exposure time. However, there was no significant difference between EPI treatments at larval densities < 8 larvae/mL. The growth of C. nippona was also examined in the following days, which showed that shell height and spat survival rates were higher in 0.5-4 larvae/mL than those in 8 larvae/mL. Therefore, 8 larvae/mL was the optimum for single oyster seed production, while a density of no more than 4 larvae/ml was the best for cultchless spats cultivation.