Study On Pre-alarming Water Quality System For Intensively Cultured Litopenaeus Vannamei

Shrimp super-intensive farming is the pillar of China's aquaculture industry. Because of disease resistance, high yield, strong adaptability and other characteristics, Litopenaeus vannamei became the one of the most important shrimp species in the fish trade. In recent years, with the high-density breeding-technology promotion, Litopenaeus vannamei has been gradually moving towards an enterprise, but the scale breeding increases not only deteriorated water quality, but also bring more and more serious diseases. Water quality is the key factor of limiting the output and quality of breed product. If it cannot be timely to take measures against the deterioration of water quality, and it will continue in the shrimp stress state, the body's immune defense system is inhibited weakened resistance to disease, causing large-scale death, shrimp farming water quality and safety become a bottleneck to the development of aquaculture industry.This experiment studied on Litopenaeus vannamei, the works were carried out in the intensive shrimp farming cycle. We continuously monitored the water quality in shrimp intensive culture systems during the whole experiment. We got a different water quality in intensive farming systems and their differences on the shrimp growth; combination of actual production, according to monitoring data of high pool, based on the use of Delphi method and SPSS analyzed the correlation between measured factors and the monitoring key factors which the departments under the authority proposed, selected the water quality factors which have significant impacts on Litopenaeus vannamei intensive farming systems.Based upon which influencing them through the method of integrated pollution index method and fuzzy evaluation method to a high pool, the paper founds the system pre-alarm model for Ammonia-N,NO2-N,pH value,dissolved oxygen,water temperature,COD.The main results are as follows:1 Assessing water quality parametersAccording to Delphi method to determine the importance of water quality factors in the farming system, the results show that DO>water temperature> Ammonia-N> pH value> NO2-N>temperature> transparency>into the drain> NO3-N>light volume> inorganic phosphate> salinity> Chlorophyll> COD> BOD5> bacteria> plankton. Although this method can solve the complexity of the water quality in water quality evaluation, but easy have led to mistakes for the subjective factors.This paper measured water quality parameters between the correlation analysis, and reference to the results with Delphi method, selected the DO,water temperature,Ammonia-N,pH value,nitrite nitrogen and COD as the evaluation parameters of the evaluation model.2 Water quality assessment modelEstablished a single-factor evaluation model according to water quality standards is Ii=Ci/C(ij).Established multi-factor evaluation model according integrated method and fuzzy evaluation method, obtained comprehensive evaluation model is Fuzzy evaluation model is Compare this two evaluation models with actual test data, the results showed that two evaluation methods could accurate to determine the deterioration of water quality under the conditions of someone factor marked particularly deterioration; In the absence of a water quality factor conditions marked particularly deterioration, especially poor situation, fuzzy evaluation method is superior to integrated method.3 Pre-alarming water quality modelEstablished pre-alarming water quality model in shrimp farming water quality factors on each of the state warning is Combined the fuzzy evaluation model with pre-alarming levels of water quality, it determined the level of water quality standards for pre-alarming and established pre-alarming water quality model is4 Early warning models in different systemAnalysis of water qualities on different farming systems, the changes of water quality of open-air semi-intensive systems are acute than the other two systems. (2) early warning to the water quality of three culture systems, getting in the breeding process, the semi-intensive system first appeared huge warning alarm in the middle culture period; the plastic greenhouse system in the culture reached the huge warning alarm later than the semi-intensive system, the water quality was moderate deterioration, the water quality of the plastic greenhouse system was better than the semi-intensive system; the high farming system did not reach above important warning in the entire trial, water quality of the high farming system was more stable. Therefore, in terms of early warning, the high culture system was the best, followed by the plastic greenhouse system and the semi-intensive system was the worst, which consistent with results of the analysis with water quality. (3) Growth of shrimp has large differences between the three different system, the production and level of shrimp size are in order:the high farming system> the plastic greenhouse system> the semi-intensive system. This result is also consistent with the conclusions of early warning. Therefore, the early warning model can work better on shrimp intensive culture systems, forecasting a timely alarm when the water quality deteriorate, ensuring the water quality under the safety culture state.