盐度对花尾胡椒鲷胚胎和仔鱼的影响

将花尾胡椒鲷（Ｐｌｅｃｔｏｒｈｙｎｃｈｕｓ ｃｉｎｃｔｕｓ）受精卵置于不同盐度的水体中进行孵化。结果表明,当盐度≤２６．４７时,花尾胡椒鲷受精卵沉于水底;当盐度≥３０．１２时,花尾胡椒鲷受精卵浮于水面。以孵化率和畸形率为指标,花尾胡相应 鲷胚胎发育的适宜盐度范围为１１．２０～４５．１７,最适盐度范围为２６．４７～３７．９５。初孵仔鱼在盐度≤２０．９９的水中沉入水底,盐度≥２６．４７则上浮。本文还报     

Closed recirculating system for shrimp-mollusk polyculture

This paper deals with a new system of aquaculture, i.e., a closed recirculating system for shrimp-mollusk polyculture. The culture system consisted of several shrimp ponds, a mollusk water-purifying pond and a reservoir. During the production cycle, water circulated between the shrimp and mollusk ponds, and the reservoir compensated for water loss from seepage and evaporation. Constricted tagelus, Sinonovacula constricta, was selected as the cultured mollusk, and Pacific white shrimp, Litopenaeus vannamei, as the cultured shrimp. The main managing measures during the production cycle were： setting and using the aerators; introducing the probiotic products timely into the shrimp ponds; adopting a “pen-closing” method for controlling shrimp viral epidemics; setting the flow diversion barriers in the mollusk pond to keep the circulating water flowing through the pond along a sine-like curve and serve as substrate for biofilm; no direct feeding was necessary for the cultured mollusk until the co-cultured shrimp was harvested; natural foods in the water from the shrimp ponds was used for their foods. Two sets of the system were used in the experiment in 2002 and satisfactory results were achieved. The average yield of the shrimp was 11 943.5 kg/hm^2, and that of the mollusk was 16 965 kg/hm^2. After converting the mollusk yield into shrimp yield at their market price ratio, the food coefficient of the entire system averaged at as low as 0.81. The water quality in the ponds was maintained at a desirable level and no viral epidemics were discovered during the production cycle.