Studies On The Optimization Of Ecological Structure In Polyculture Of Litopenaeus Vanamei With Cyclina Senensis And Gracilaria Lichevoides

With the development of mariculture, its impact on marine environment was concerned by more and more people. The shrimp industry plays important role in mariculture of China. The statistic data showed that the yield of shrimp or prawn in 2003 was 5.36×10⁵ t, therefore, the influence of shrimp industry on marine environment deserves more attentions. How to improve environment in culture system, reduce the accumulation of nutrients in culture system and decrease the negative impacts on marine ecosystem caused by effluence from shrimp ponds is a vital problem need to be solved. These studies were designed and conducted to optimize the ecological structure of polyculture of Litopenaeus vannamei with Cyclina sinesis, L. vannamei with Gracilaria lichevoides, and L. vannamei with C. senensis and G. lichevoides, and economic benefit and ecological efficiency of three polyculture systems, two bi-species ones and tri-species one, were also evaluated with land-based experimental encloseures set in one pond. The chief results were as follows:1. An experimental study on polyculture of Litopenaeus vannamei with Cyclina senensisFour stocking density of C. sinesis (7, 15, 30 and 45 ind·m^-1) combined with one stocking density (30 ind·m^-2) of L. vannamei were arranged in 20 enclosures. The duration of experiment was 60 d.The results showed that the bodyweight of shrimp was ranged from 5.98 to 6.25 g· ind^-1, averaged in 6.15 g, the survival rate of shrimp was 68.91%～86.32%, averaged in 78.54%, and the net production of shrimp was changed from 1290.20 to...