江蓠与新对虾、青蟹混养试验

POLYCULTURE EXPERIMENTS ON CRACILARIA,MET APENAEUS AND SCYLLA

细基江蓠繁枝变种与新对虾、青蟹混养试验结果表明:(1)细基江蓠繁枝变种生长的最适温、盐度分别为 17—30℃和 17—29‰,这一温、盐度范围也适合新对虾和青蟹的生长;鱼塭海水的温、盐度变化与沿海不同,因此,移植野生江蓠到鱼塭养殖时要考虑这一特点。(2)江蓠在不同的生长季节的最适生长水层是不同的。(3)江蓠的主要有效氮是 NH_4^+,而新对虾、青蟹的排泄物可分解出大量的NH_4^+。这样,江蓠与新对虾、青蟹形成互为有利的共生关系,有利于养殖水体水质的稳定,因此,混养时它们生长都较快,产量和经济收入也较高。

Polyculture experiments on Gracilaria tenuistipitata var. liuiZhang et Xia f. nov., Metapenaeus ensis De Haan, M. intermedius Kishinoye andScylla serrata Forskal have been investigated and their results are as follows: 1. The optimum temperature and salinity for the seaweed growth ranges be-tween 17--30°Cand 17--29‰ respectively,and these are also suitable for growthofthe shrimps and the crab. The changes of water temperature and salinity in thefish pond are different from those in the coastal waters, which must be conside-red when the wild algae of Gracilaria is transplanted from coastal waters to fishpond. 2. The specific growth rate of this plant varies with water depths of seaso-nal replacement. The optimum water depths for Gracilaria growth in the fish pond are 20--50cm during months of January to April, 50--80cm of May to June,70--80cm of July to August, 35--70cm during September and 20--70cm of Octoberto December, respeetively. 3. The main nitrogen nutrient available for the uptake of Gracilaria is NH_4^+,while the excreta from the shrimps and the crab contains much NH_4^+. 4. Polyculture of marine algae and crustacea can promote growth each other,such as improving Water circumstance, increasing yield and more income, etc.Therefore,the polyculture is a good promising method for mariculture productionin coastal states.