Studies On The Distribution Of Crassostrea Oyster And The Gonadal Development Of Crassostrea Ariakensis In Coastal Waters Of Fujian

The study includes two parts:1.The distribution of Crassostrea oyster in Fujian ocean.2.The studies on gonadal development of Crassostrea ariakensis.Part one:In present studies,we used the multiplex species-specific pcr to understand the distribution of Crassostrea oysters in Fujian coast of China.The multiplex species-specific PCR assay is a fast,simple and reliable method for the identification of oysters.It can potentially identify several species in one reaction without further manipulation.Multiplex species-specific PCR has been used for the identification of other bivalve species.A total number of 657 oysters were randomly collected from 11 sites along Fujian coast,from April to July of 2007.Among them, 327 oysters were subjected to a mitochondrial COI gene-based speciation analysis. Results showed that 4 species were identified:C.angulata(200 samples),C. ariakensis(101 samples),C.sikamea(20 samples),C.hongkongensis(6 samples).Part two:Based on the part one's results,we studied the gonadal development of C.ariakensis,which were collected from the entrance of Jiulong River.The studies lasted one whole year.When the oyster's gonad had not developed and the soft body of the oyster was limpidity,we started to collect samples at the first time.From then on,we gathered samples every two months.When the oyster's gonad was mature,we observed oysters biweekly.At least 20 C.ariakensis individuals were collected at one time,and the whole weight and the shell weight of each sample was measured respectively.Then,we observed developmental condition of each oyster's gonad and analysed the samples' gonadal maturity,including the characteristics of gonad,the distribution of gonad,the percentage of gonad covering the soft body,the presence or absence of digestive tract,the color of gonad,the maturity of gonad,the presence or absence of eggs or sperms when pressed,and so on.The results were recorded.Then, the soft bodies were removed into a vacuum drying oven.After more than 24 hours of drying at 65℃,the dried meat was obtained.The dried meat was measured to calculate the condition index.On the other hand,20 C.ariakensis individuals were anatomized to fix in Davidson' fixative solution.After at least 48 hours,the fixed gonad was cutted apart from the soft body and then embedded in paraffin.The thickness of the paraffin section was 4-6 um.And then,the paraffin section was stained in hematoxylin-eosin staining buffer.Techniques of microphotograph was used to record the results.So combined these two methods:morphology and cytology, the stage of the gonad of C.ariakensis was clear.Results shows that:near the entrance of Jiulong River,the reproductive cycle of C.ariakensis is one year,and the breeding season of C.ariakensis is from the middle March to the late May,when is the best time to collect seedlings.