Optimization, Nitrogen And Phosphorus Budgets And Emergy Analysis Of Different Portunus Trituberculatus Polyculture Systems

I.An Experimental Study on Structure Optimization for Polyculture of Portunus trituberculatus, Litopenaeus vannamei,Ruditapes philippinarum,and Gracilaria lichevoides.The study was designed and conducted to optimize the structure of polyculture for Portunus trituberculatus, Litopenaeus vannamei, Ruditapes philippinarum and Gracilaria lichevoides, and to compare their water quality parameters. Crabs, shrimps and clams were mixed with Gracilaria lichevoides, six treatments were designed respectively was C, CS, CSB, CSBJ], CSBJ2, CSBJ3(C:crab; S:shrimp; B:clam; J: Gracilaria lichevoides). The result showed that the individual specifications of crabs in different treatments were not significantly different (.P>0.05); The highest yield of crab were 3255.24kg/hm2 for the treatment of CSBJ2; The body weight, sgr and survival rate of CSBJ1 and CSBJ2 were significantly higher than other treatments (P<0.05); The yield of CSBJ2 shrimp was the highest and was higher than other treatments significantly (P0.05); Breeding Gracilaria lichevoides in the pond with clams could increase the survival rate of clams, but there were no significant difference between the treatments (P>0.05); During the period of culturing, there were significantly lower NO2-N in CSBJ2 than in other treatments on the whole (P<0.05); The treatments which mixed with Gracilaria lichevoides could significantly reduce the concentration of ammonia nitrogen (P<0.05). Total nitrogen and total phosphorus concentration of.CSBJi and CSBJ2 were significantly lower than other treatments in the middle and late cultivation (P<0.05). In this study, Portunus trituberculatus system mixed with Gracilaria lichevoides in suitable density could improve water quality, reduce the concentration of total nitrogen, total phosphorus and ammonia nitrogen, nitrate nitrogen and improve the production and survival rate of Portunus trituberculatus and Litopenaeus vannamei. Under the condition of this research, the treatment giving the best culturing benefit was crabs at 6 ind/m, shrimps at 45 ind/m2 and clams at 30 ind/m2. Gracilaria lichevoides at 0.36kg/m2.2. An Experimental Study on Nitrogen and Phosphorus budgets in Polyculture of Portunus trituberculatus, Litopenaeus vannamei, Gracilaria lichevoides and Liza haematocheila.The budgets of nitrogen (N) and phosphorus (P) were studied with land-based enclosures for various polyculture systems of Portunus trituberculatus, Litopenaeus vannamei,Ruditapes philippinarum, Liza haematocheila and Gracilaria lichevoides. The results showed that the feed was the main nitrogen (accounting for 84.58%～90.12%) and phosphorus (accounting for 96.70%～97.71%) input in the enclosures while the marine water supply provided 7.36%～11.95%of nitrogen inputs and 0.41%～1.15% of total phosphorus inputs. Among the output items, the major outputs of nitrogen and phosphorus were in the sediments, which accounted for 19.93%～45.40% of total nitrogen outputs and 17.80%～51.30% of total phosphorus outputs. The biomass harvest compromised 13.52%-56.05%of total nitrogen outputs and 20.92%～34.77% of total phosphorus outputs. The highest utilization efficiency of nitrogen and phosphorus is observed in the treatment CSBJ, followed by CSBF. The treatment giving the best culturing benefit was CSBF and CSBJ.3. The emergy analysis of different Polyculture Systems of Portunus trituberculatusSwimming crab(Portunus trituberculatus), white shrimp (Litopenaeus vannamei) and short -necked clam(Ruditapes philippinarum) and fish(Liza haematocheila) were cultured in different polyculture combinations. Four combinations were designed, i.e., the monoculture of crab (C), polyculture of crab and shrimp (CS), polyculture of crab and shrimp and clam (CSB), polyculture of crab and shrimp and clam and fish (CSBF). Both physical and monetary input and output data about the culturing processes were collected. Emergy analysis, which both considers the economic aspect and the natural contribution through meaningful comparison across different systems, has been proved to be a powerful tool to assess the ecological economic systems and processes, especially in mariculture field. In this paper emergy analysis method is employed to evaluate the Polyculture Systems of Portunus trituberculatus. A suite of emergy indices were applied to characterize the resource use, environmental impact and the overall sustainability of the studied systems. The results showed that the TR of CSBF was significantly lower than that of other combinations (P<0.05). The ELR of CSBF is 105.92, slightly higher than that of other combinations, but the EERY of CSBF is significantly higher than that of other combinations (P<0.05). The EISD of CSBF was significantly higher than that of other combinations (P<0.05). Taking all the system indices into consideration, CSBF is the best syetem with higher economic benefits and relatively smaller impact on the environment and much sustainable.