Study On Physical And Chemical Biology Factor Of Polyculture Systems Of Litopenaeus Vannameia And Mugil Cephalus In Intensive Pond

With the development of shrimp culture,Because of the high yield, high efficiency and high intensive, the high density aquiculture mode gradually becomes the main breeding mode in the coastal area of southern China .But because the high density, difficulty of management is great. Thus, many problems appears, such as too much residual bait, Water environment easily deteriorated, epidemic outbreaking easily. It serious influences the healthy development of Chinese shrimp industry. In this paper, experiments was taking on comparing pond culturing of single species with polyculture pond of litopenaeus vannamei and mullet on water physical and chemical indicators, the number of phytoplankton species, pond microbial changes, the heavy metal content in water and shrimp and economic benefits, to provide theoretical basis for finding healthy culture mode.In this experiment, Litopenaeus vannamei and Mugil cephalus polyculture pond and Litopenaeus vannamei monoculture pond as the main object of study, the two ponds are for the intensive pond, the same configuration, and management.According to the experimental method of Ocean survey standard (GB/T12763.4-2007), the physical and chemical indicators such as temperature,salinity, dissolved oxygen, pH value, chemical oxygen demand (cod), suspended matters, active phosphorus, nitrite nitrogen, nitric nitrogen and ammonia nitrogen of the pond culturing of single species and polyculture pond were detected respectively. The results showed that there were no significant difference between the two ponds in these factors such as temperature, salinity, dissolved oxygen, PH value, chemical oxygen demand (cod), suspended matters, nitrite nitrogen, nitric nitrogen and ammonia nitrogen(P>0.05). Among them, the temperature and salinity almost identical, PH value, dissolved oxygen effected more by human factors, the content of three kinds of nitrification is higher in later period. There is significant difference between the two ponds in COD, active phosphorus and suspended matters in the middle and later culturing period(P<0.05),while in the early stage had no significant difference(P>0.05).In the entire culturing process, COD and suspended matters showed rising trend, while active phosphorus showed reduced tendency. Using spectrophotometer method to detect the content of chlorophyll a in the water of the two culturing modes. Counting and statistiking the species and number of phytoplankton, the number of heterotrophic bacteria and vibrio. The results indicated that in the two culturing modes, there were no significant difference in the content of chlorophyll a and the number of phytoplankton in the early and middle stage(P>0.05),but there was significant difference in the later stage(P<0.05).The content of chlorophyll a and the number of phytoplankton in polyculture pond is significantly greater than single raise pond. Polyculture pond has a good feature of a smaller proportion of relative superiority species and has a better diversity of algae. Under the two mode, the number of heterotrophic bacteria has no significant difference(P>0.05).But, the number of vibrato has a significant difference (P<0.05),the number in polyculture pond is much lower than the single specie pond in the same period.Considering form the angle of the safety of shrimp products from polyculture pond and the distribution and flow of heavy metal ions , using inductively coupled plasma mass spectrometry (ICP-MS) to detect the content of the three heavy mater ions Cu,Mn,Cd in pond water, shrimp mince,mullet muscle,bottom sediment and fodder. The results showed that there was no significant difference in the content of the three ions in pond water and shrimp mince in the two mode(P>0.05), polyculture pattern has no significant influence on the content of the three ions in pond water and shrimp mince. The heavy metal content in pond water and shrimp mince met the safety requirements of fishery water quality and aquatic products. Litopenaeus vannamei and mullet polycultivation mode is safe.Through the determination of shrimp length and weight in the two ponds in the later stage of culturing, comparing the influence of the polycultivation mode on Litopenaeus vannamei growth. Results showed that change trend of litopenaeus vannameis'weight and length almost has no difference. In the later stage of culturing, the weight and length of shrimps in ploycultive pond is slightly larger than the pond culturing of single species, but there is no significant difference in the two pond(P>0.05). Culturing mode has little influence on shrimp growth.On the aspect of breeding benefit, the statistical calculation results show that the profit for polyculture pond is 26015 yuan per 1000m~2,while the pond culturing of single species is 22590 yuan per 1000m~2. The shrimp production of Polyculture pond is 6625kg and the specific yield is 1656kg per 1000m~2.The mullet production is 1350kg and the specific yield is 337.5kg per 1000m~2.The profits of Polyculture pond is 26015yuan per 1000m~2;The shrimp production of monoculture pond is 3703kg, and the specific yield is1596kg per 1000m~2. The profits of monoculture pond is 22590 yuan per 1000m~2。The polyculture pond has a increased profits of 3424 yuan per per 1000m~2.The profit growth rate is 15.2%. Thus, the polyculture mode has a better economic benefits...