Comparative Of Two Culture On Growth And Histological Study On The Development Of Gonad Of Isognomon Ephippium

This research mainly focuses on the effect of different feeding methods(hanging and bottom sowing) on the growth of Isognomon ephippium(I. ephippium) and the development of gonad of I. ephippium.That the study founds Suitable breeding method by comparing two kinds of farming methods on the difference of effect of the growth of I.ephippium aims to providing scientific basis and theoretical guidance for the mariculture of I. ephippium; and the basic law of the development of gonad of I. ephippium was discovered by observing the histological sections of the gonad development of I.ephippium aims to providing theoretical guidance for the artificial propagation and pearl production of I. ephippium.The major research results were as follows:1.The effect of hanging on the growth of I. ephippiumThere was no significant difference(P > 0.05) within the growth of juveniles、young and adult I. ephippium of hanging,and the growth rate from high to low in turn was juveniles、young and adult.2.The effect of bottom sawing on the growth of I. ephippiumThere was no significant difference(P > 0.05) within the growth of juveniles 、young and adult I. ephippium of bottom sowing,and the growth rate from high to low in turn was juveniles、young and adult.3.Comparison between hanging and bottom sawing in the growth and survival of I.ephippiumThe difference was significant(P < 0.05) within the growth rate of juveniles、young and adult I. ephippium between hanging and bottom sowing.Compared to juveniles、young and adult I. ephippium of bottom sowing,the growth rate(According to shell length)increase of juveniles、young and adult I. ephippium of hanging were 29.4%、23.1% and12.9%.As to the survival rate, it was hanging that was significantly higher than that of bottom sowing before September, but significantly lower in October.4.law of the gonad development of I. ephippiumThe development of both male and female gonads of I. ephippium was devided into the proliferation stage, increasing stage, maturation stage, breeding stage and suspensivestage, with specific characteristics of gonads and germ cells. In the proliferation stage,oogonium and spermatogonium were produced in new follicles; In increasing stage, the area of the gonads, the number of follicles and germ cells were increased obviously.Massive oocytes and spermatocytes existed in follicles. In maturation stage, the follicles were filled with oocytes, which had bright germinal vesicle and clear nucleolus, and sperms with red tails. In breeding stage, mature germ cells were released from damaged follicles. In suspensive stage, follicles were shrinked and no germ cells were found. The reproductive cycle of I. ephippium was one year, including proliferation stage from May to June, increasing stage from July to August, maturation stage from August to September,breeding stage from September to October, suspensive stage from October to November.Most gonads did not grow from December to next April.5.The effect of temperature and salinity on the gonad development of I. ephippiumThe optimum temperature and salinity of the gonad development of I. ephippium respectively was28.2℃-32.1℃ and 8.9‰-17.6‰.There was almost no development of the gonad when the temperature was very low from December to April of next year. The gonad begun to development with the temperature rising at late April,then the speed of development accelerate at May and June, and the gonad would mature at October, then completing discharge at September and October.The gonad would atrophy with the temperature reducing after November.There was almost no development of the gonad when the salinity was very high from January to March.The gonad begun to development with the salinity reducing at late March,then the speed of development accelerate at May and June, and the gonad would mature with the minimum salinity at July and October, then completing discharge when the salinity was suitable at September and October.The gonad would atrophy with the salinity rising after November.