Effects Of Scatophagus Argus Polyculture On The Ecological Factors And Energy Budget In Shrimp Ponds

In this study, hydrochemical indexes （temperature, salinity, pH and dissolvedoxygen（DO）, chemical oxygen demand （COD）, suspended matters, ammonia nitrogen andnitrite nitrogen）, as well as the composition and quatity of plankton population weredetected according to the methods of Ocean survey standard （GB/T12763.4-2007） in themonoculture pond （Litopenaeus vannamei） and the polyculture pond （L. vannamei andscatophagus argus）. Energy budget and economic benefits of the two ponds werecompared. Results could provided a new, feasible and healthy culture model for the shrimpculture, and the main results as follows:1. There were no significant difference in temperature, salinity, pH and the DObetween the two ponds （P>0.05）. However, the content of COD, suspended matters,ammonia nitrogen and nitrite nitrogen in the monoculture pond increased faster than that inthe polyculture pond at the end of experiment, and significant difference was foundbewtween the two ponds （P＜0.05）.2. Species of phytoplankton and zooplankton were basically same in the two ponds.The dominant species were diatoms at the early stage, and the cyanobacteria andChlorophyta at the late stage. The average density of phytoplankton and zooplankton were1.4.108cell/L and1567ind/L, respectively in the polyculture pond, and1.1.108cell/L and2055ind/L, respectively in the monoculture pond. The abundance of phytoplankton in themonoculture pond was higher than that in the polyculture pond at the late stage ofexperiment （P＜0.05）, but the reverse result was observed in zooplankton （P＜0.05）.3. The solar radiation energy input was1345.08MJ.m^-2during the experiment period,and the solar energy utilization rates in the polyculture pond （0.29%） was higher than that（0.26%） in the monoculture pond （P＜0.05）. The photosynthetic energy efficiency were1.07MJ.m^-2and0.95MJ.m^-2, respectively in the polyculture and the monoculture pond,and increased by12.63%in the polyculture pond （P＜0.05）. Compared to the monoculturepond, feeding energy conversion efficiency, total energy conversion efficiency and feedingenergy consumption per unit net yield increased by0.31%,7.4%and3.46%, respectively,but the total energy consumption per unit net yield decreased by1.26%. However, nodifference was found between the two ponds （P>0.05）. The sediment energy in thepolyculture (0.75MJ.m^-2) and the monoculture (1.26MJ.m^-2) pond accounted for totalinput energy were2.40%and4.30%, respectively, and significant difference in sediment energy were found between the two ponds （P＜0.05）.4. The weight and length of L.vannamei in polyculture pond were slightly higher thanthat in the monoculture one, but no significant difference was found between them. Theyield of shrimp and S. argus was550kg and39kg, respectively in the polyculture pond,and profit was4321yuan.However, shrimp yield and the profit was538kg and2196yuan,respectively in the monoculture pond. The profit increased by46.67%in the polyculturepond. Results revealed that this polyculture model could improve significantly both thewater quality and the energy efficiency, and balance the plankton population, and thenachieved more economic income.