偏顶蛤胚胎和幼虫发育及温度对其浮游幼虫生长和发育的影响

Development of embryo and larva of Modiolus modiolus and effects of temperature on growth and development of the pelagic larva

在室内条件下,人工诱导偏顶蛤（Modiolus modiolus）产卵并在显微镜下对其胚胎和浮游期幼虫的形态进行连续观察和拍照,并采用实验生态学的方法,研究温度对其浮游期幼虫生长和发育的影响。结果显示,偏顶蛤亲贝人工催产时,以流水刺激4 h,阴干12 h为宜。偏顶蛤卵呈圆形或卵圆形,沉性卵,卵径为（82.6±3.2）μm,精子鞭毛型,全长约50μm。在水温19-21℃下,偏顶蛤受精卵发育至D形幼虫（壳长104.0μm±4.3μm）、匍匐幼虫（壳长255.8μm±15.0μm）和早期稚贝（壳长329.1μm±5.8μm）分别历时20.5 h、20 d和36 d。水温是影响偏顶蛤幼虫生长和发育的主要因素之一,幼虫适宜水温为15-20℃,15℃组幼虫畸形率显著低于20℃组,生长率20℃组最高达5.4μm/d;水温25℃和30℃下,幼虫畸形率均显著高于15℃组和20℃组,并分别在第6天和第4天全部死亡。相对于高温而言,偏顶蛤幼虫对低温的耐受能力更强。本文旨在为偏顶蛤繁殖生物学和苗种繁育技术提供基础资料。

To fill the gap of morphology development embryo and pelagic larva of Modiolus modiolus and provide basic data for the breeding technology, an experiment was conducted where matured zygotes were harvested by artificial inducing spawn and the morphology of embryo and pelagic larva of M. modiolus was observed and recorded under microscope in this study. The effects of seawater temperature on growth and development of the pelagic larva was studied through experimental ecology methods. Results showed that stimulation time for artificial spawning by air-drying should be 12 h when flowing water stimulation was 4 h. The demersal eggs were shaped ellipse（82.6 μm±3.2 μm in diameter）, while the sperms were the type of flagellum（about 50 μm in total length）. The embryonic development from zygote to D-larvae stage（104.0 μm±4.3 μm in shell length）, creeping larvae stage（255.8 μm±15.0 μm in shell-length） and early juvenile stage（329.1 μm±5.8 μm in shell length） lasted for 20.5 h, 20 d and 36 d, respectively. The results testified that seawater temperature is one of the crucial factors on the growth and development of the pelagic larva. The suitable temperature was from 15 ℃to 20℃. The abnormality rate of the larvae at 15 ℃was significantly lower than those at 20℃. The highest growth rate was 5.4 μm/d in group 20℃. In 25 ℃and 30 ℃groups, the abnormality rates were significantly higher than those at 15 and 20℃ ℃, and the larvae all dead at the sixth day and the fourth days respectively. The larva showed stronger tolerance to lower temperature than higher temperature.