A Comparative Study of Intensive Litopenaeus vannamei Culture on Four Bottom Substrates Without Water Change

The effect of four bottom substrates, oyster shell powder(OP), sugarcane bagasse(SB), a mixture of OP and SB(OS) and fresh soil(FS), on the water quality and bacterial and zooplankton density of intensive shrimp(Litopenaeus vannamei) culture tanks without water change and the growth performance of cultured shrimp were compared in this study. At the end of a 110 days culturing trial, the total ammonium-N(TAN) of the water on SB and the nitrite nitrogen(NO2-N) on OS was significantly lower than that on the other substrates(P<0.05), which coincided with the high density of ammonium- and nitrite-oxidizing bacteria in the water on SB and OS, respectively. The concentration of chlorophyll a(Chl a) increased slowly on OP, SB and OS but remained low on FS. The density of total bacteria on OP, SB and OS was one order of magnitude higher than that on FS, and the density of zooplankton on SB and OS was significantly higher than that on FS or OP(P<0.05). The improved water quality and increased density of bacteria and zooplankton on SB and OS may have had a synergistic effect on shrimp culture, improving its growth performance(high survival rate and yield and low feed conversion rate). SB and OS were more effective for improving the growth performance of intensively cultured L. vannamei without water change than OP and FS. To our knowledge, this study presents the first evidence regarding the effect of different bottom substrates on intensive shrimp culture.

The Effect of Three Culture Methods on Intensive Culture System of Pacific White Shrimp (Litopenaeus vannamei)

Different culture methods may affect the intensive culture system of Pacific white shrimp(Litopenaeus vannamei) regarding water quality and growth and economic performance.This study evaluated the potential effects of three culture methods through cultivation of juvenile shrimps under consistent tank management conditions for 84 d.The three methods involved shrimp cultivation in different tanks,i.e.,outdoor tanks with cement bottom(mode-C),greenhouse tanks with cement bottom(mode-G) and outdoor tanks with mud-substrate(mode-M).Results showed that water temperature was significantly higher in mode-G than that in mode-C(P < 0.05).In contrast to the other two treatments,mode-M had stable pH after 50 d cultivation of shrimps.In the mid-late period,the average concentrations of TAN,NO2-N,DIP and COD were significantly lower in mode-M and mode-G compared with those in mode-C(P < 0.05).Despite lack of differences in the final shrimp weight among different treatments(P > 0.05),mode-M had significantly higher shrimp yield,survival rate and feed conversion rate(P < 0.05) than other modes.There were significant differences in revenue and net return among different treatments(P < 0.05).These demonstrated that the treatments of mode-G and mode-M were conductive to the intensive culture system of L.vannamei.