Research On Reproductive Biology And The Growth Of Shellfish Larvae Of Tapes Dorsal

This paper was conducted to investigate the relationship between structure and function on the development of the gonad in the Tapes dorsal, we used Tapes dorsal as the research object, the sex gland and embryonic and larval development were observed by microscopic and routine histological techniques.The results and conclusion included the following aspects:Trial 1:This study was conducted to examine gonad development during one year and the relative fatness index by histological examination. The results showed that the fertilized eggs of adult Tapes dorsal are spawned by way of egg masses from early August to March next year.There are two spawning peaks,one is at the 10th and 11th month, and th other is at the 3th next year. They are dioecism and sexual cell become mature and emission in batches.gonad development can be roughly divided into five fields:proliferative phase, growth stage, mature stage, spawning stage, telogen stage. The relative fatness judgment index for gonad developmen, which had similar trends with annual variation of the relative fatness.Trial 2:Artificial induced spawning of Tapes dorsal was studied in the conditions of drying in the shade and ammonia water stimulation method, and obtained the fertilized eggs, the embryonic and larval development were observated and recorded by photo.Trial 3:This experiment was conducted to research the effect of sediment,temperature and salinity on the larval survival and growth rates of Tapes dorsal. The results showed that the suitable temperature for young growth ranged from 20 ? to 30?,and the optimal temperature ranged from 26 ? to 30?.The suitable salinity ranged from 20 to 40, and the optimal salinity ranged from 25 to 35.The young mollusk tolerated with high-salt stronger than low-salt, but the growth rate of mollusk at low salinities were significantly higher than at high salinities.It found that substratum which was mud mixed sand was suitable to the young mollusk, and the half mode substrate was higher for the growth and survival rate to juvenile mollusk.