瘤背石磺滩涂生态繁殖的初步研究

2006年6~10月,在长江口北支崇明沿岸的芦苇滩涂上进行了瘤背石磺生态繁殖的实验,观察了瘤背石磺繁殖期的性腺发育、交配与产卵、生殖性能、胚胎与幼体发育和繁殖期的其它生态习性。结果表明:(1)瘤背石磺的性腺发育可以初步分为四期,7~8月份亲本石磺的性腺发育主要处于Ⅲ期和Ⅳ期,9~10月份亲本石磺的性腺主要处于Ⅱ期和Ⅲ期,5g以下的当年繁殖个体性腺发育均处于Ⅰ期;(2)实验区的瘤背石磺多为两个体间的交配,夜间和白天均可见交配个体,7~8月初为交配盛期,9月中旬后很少见交配个体。实验区的瘤背石磺有3个产卵高峰期,最后一个产卵高峰期的产卵量(8月28~29日)远低于前两个产卵高峰期,单只瘤背石磺每次所产卵块面积为10~40 cm2之间,平均每次产卵量为(10.14±3.56)×104cell/只亲本石磺,单个受精卵湿重为(8.95±0.55)μg,受精卵的孵化率为(92.50±3.63)%;(3)实验区瘤背石磺胚胎发育时间为4~10 d,孵化的面盘幼虫10 d后可以顺利发育到匍匐幼虫阶段,匍匐幼虫经过15 d左右可以发育成0.2 g左右的幼体石磺,但是成活率极低,其变态过程和变态条件不详。

The study of ecological reproduction of Onchidium struma in wetland

During June to October of 2006,the experiments and investigations were conducted on the gonadal development,mating,spawning,reproductive performance,embryonic development,larval development and other habitus during the reproductive season of Onchidium struma on the wetland along the north coast of Chongming island.It came to the conclusions as follows:(1) the process of the gonadal development could be divided into four stages,the gonad of broodstock Onchidium struma developed into stage Ⅲ or stage Ⅳ from July to August,while the gonad degenerated into stage Ⅱ or stage Ⅲ after September.The gonad of juvenile Onchidium struma was always stage Ⅰ;(2) the mating always occured between two individuals in the net-closed area,the period from July to August was mating peak.There were three main spawning peaks during the investigative period,however the egg production produced by the last peak was significantly less than those of other two peaks.The egg mass produced by each broodstock covered 10~40 cm2,with the egg production of(10.14±3.56)×104 eggs/ind,and the wet weight of single ferlized egg was(8.95±0.55)μg.The hatching rate of egg was(92.50±3.63)%;(3) The period of embryonic development was 4~10 d,which was shorter than those of indoor embryonic development.After approximatly 10d,the big veliger could developed into creeping larva.Although the metamorphosis process and requied condition are still unknown,some creeping larva could developed into juvenile Onchidium struma with the body weight about 0.2 g,but their survival rate was very low.