砗蚝(Hippopus hippopus)的人工繁育

ARTIFICIAL BREEDING OF HORSE'S HOOF CLAM HIPPOPUS HIPPOPUS IN SOUTH CHINA SEA

于2016年4—9月开展了砗蚝(Hippopus hippopus)人工繁育技术研究。采用五羟色胺进行催产、促使配子排放;精卵分别收集,进行异体间受精以避免自交;受精卵经过30h孵化,选出600万D形幼虫进行培育。砗蚝的早期生活史与砗磲(Tridacna spp.)相似,经历前期面盘幼虫、中期面盘幼虫、后期面盘幼虫、足面盘幼虫、单水管稚贝、双水管稚贝、外套膜触手稚贝、幼贝等阶段。与砗磲不同的是,砗蚝怀卵量较少,但卵径较大,D型幼虫也较大,幼虫趋光性更强,壳长2.0mm以后外套膜不伸出壳缘外,幼贝贝壳形态也不同于砗磲。同砗磲幼虫一样,砗蚝幼虫需要构建虫黄藻系统之后,才能出现鳃、次生壳等,从而完成变态成为稚贝。砗蚝幼虫变态率较低,仅为1.4%。中间育成期间,丝状藻和锥形螺是稚贝培育的主要敌害,需及时清理才能确保稚幼贝正常生长发育。经过120d的精心饲育,培养出平均壳长6.3mm幼贝500余个。本研究为进一步开展砗蚝人工繁育、中间育成、增殖放流、资源修复及移植保育提供了参考。

Artificial breeding of horse＇s hoof clam Hippopus hippopus was conducted at the Tropical Marine Biological Research Station in Hainan in April—September, 2016. The results show that serotonin can effectively promote gamete release. Six million D-shaped larvae were obtained after 30-h incubation by cross-fertilization to avoid self-fertilization. The horse progeny underwent early veliger, middle veliger, late veliger and pedi-veliger larvae, single-siphon and double-siphon spat, mantle tentacles spat, and youth during the early history life stage, which is same to that of fluted giant clams excepted that the fecundity of horse＇s hoof clam is less than that of fluted giant clam, while egg size and D larvae are larger than those of fluted giant clam. Light phototaxis of horse＇s hoof clam larvae was stronger than that of fluted giant clam, and shell shape is different from each other. Larvae can complete metamorphosis forming spat after establishing the zooxanthellae tubular system, growing out gill, second shell, etc. Metamphosis of larvae was only 1.4% during the settling stage. Filamentous algae and Oncomelania are offspring of cultivating key predators during the grow-out stage. Hence, the predators should be cleaned out regularly to ensure normal growth and development for progeny. Some 500 youth progeny in shell length of 6.3 mm were obtained after 120-day rearing. This study on the artificial breeding for horse＇s hoof clam may provide theoretical basis and reliable techniques for conducting giant clam aquaculture and transplantation work.