Comparison Of Physicochemical Factors And Economic Benefits In Different Trionyx Sinensis Pond Farming Model

Chinese softshell turtle(Trionyx sinensis)is a precious special aquatic product in China.It is popular among consumers at home and abroad for unique flavor and high medicinal value.This paper compares the model of high density pond(high density without aquatic plants),low density ponds(low density with aquatic plants),turtle-lotus ponds(Soft-shelled turtle was cultured in lotus pond)and turtle-Trapa bispinosa ponds(Soft-shelled turtle was cultured in pond which is full of T.bispinosa).By comparing the water quality index,phytoplankton and economic benefits of the four turtle pond farming models,we hope to provide data support for the pond culture of turtle from the aspects of physicochemical factors and economic benefits.According to the water parameters and comprehensive nutritional status index,the dissolved oxygen(DO),ammonia nitrogen(NH4+).nitrite nitrogen(NO2-),total nitrogen(TN)-total phosphorus(TP),chemical oxygen consumption(CODMN),chlorophyll a(Chla)and comprehensive nutritional status index(TLI)in the high density pond were significantly higher than those in the other models,and the SD in the high density pond were significantly lower than other models(P<0.05).A total of 77 genera in 9 phytoplankton families were recorded in the four models.The common dominant species among the four species were Microcystis,Dinoflagellates,Cryptophyceae,Cystis microcystis and Desmothrix.The shannon-wiener diversity index of phytoplankton showed that there was no significant difference between the four breeding modes(P>0.05):turtle-lotus ponds>low density ponds>high density ponds>turtle-Trapa bispinosa ponds.All the four breeding modes were-a medium pollution.The Pielou evenness index showed that the Pielou index(J)was not significantly different from each other(P>0.05):low density ponds>turtle-lotus ponds>high density ponds>turtle-T.bispinosa ponds.The Margalef richness index showed that there were significant differences among high density,low density ponds,turtle-T.bispinosa ponds and turtle-lotus(P<0.05):turtle-lotus ponds>low density ponds>high density ponds>turtle-T.bispinosa ponds.Turtle-lotus ponds are the clean type.Turtle-T.bispinosa,high density ponds and low density ponds are of low pollution type,and the degree is decreasing.The four models recorded 7 cladocera belonging to 6 genera,3 calanoida belonging to 3 genera,6 cyclopoida belonging to 6 genera.The common dominant species were Paracyclops fimbriatus,Mesocyclops leuckarti,Thermocyclops taihokuensis.The shannon-wiener index of zooplankton showed that there was a significant difference between high density ponds,turtle-lotus ponds,turtle-Trapa bispinosa ponds and low density ponds(P<0.05).The Pielou evenness index showed that there were significant differences between high density ponds,turtle-T.bispinosa,turtle-lotus ponds and low density ponds(P<0.05):low density ponds>turtle -T.bispinosa>turtle-lotus ponds>high density ponds.The Pielou evenness index of the four breeding models was poor nutrition.Margalef richness index showed that there was no significant difference between the four models(P>0.05),and the order was as follows:low density ponds>turtle-T.bispinosa>high density ponds>turtle-lotus ponds.The richness index of the four breeding models was a-medium pollution.The economic benefits of different breeding modes were successively as follows:high density ponds>turtle-lotus ponds>turtle-.bispinosa ponds>low density ponds.On the contrary,the ratio of production to investment was in turn:low density ponds>turtle-T.bispinosa ponds>turtle-lotus ponds>high density ponds.