混养鲮对凡纳滨对虾养殖池塘浮游生物群落结构的影响

Effects of Ployculture with Cirrhinus molitorella on Plankton Community in Intensive Shrimp(Litopenaeus vannamei) Farming Pond

为探索凡纳滨对虾(Litopenaeus vannamei)适宜的养殖模式,跟踪调查了2口凡纳滨对虾养殖池塘[前期单养对虾,后期混养鲮(Cirrhinus molitorella)],测定了混养前、后养殖水体中浮游动、植物的群落组成,水质指标以及凡纳滨对虾生长情况。结果显示:混养后,养殖水体总氮、氨氮、硝酸盐、亚硝酸盐含量均显著低于混养前(P<0.05),磷酸盐含量显著高于混养前(P<0.05),混养模式对虾养殖产量提高;经鉴定,混养前浮游植物共6门46种,混养后共6门44种,混养前、后对虾池塘浮游植物的密度和生物量分别为167.32×10~6个/L和7.84 mg/L、53.69×106个/L和4.24mg/L,混养后浮游植物密度及生物量均降低;浮游动物混养前共4门23种,混养后共4门17种,混养前、后对虾池塘浮游动物密度和生物量分别是3 014.6 ind./L和3.981 mg/L、1 201.65 ind./L和0.968 mg/L,混养后浮游动物生物量及密度均降低;混养后,浮游植物多样性提高,浮游动物多样性降低。以上结果表明,与单养模式相比,混养模式能降低养殖水体总氮、氨氮等含量,减少浮游生物数量,提高浮游植物多样性,同时降低浮游动物多样性,促进养殖水体藻相稳定,有利于提高对虾产量。

To study the effects of polyculture on plankton community structure in intensive shrimp（ Litopenaeus vannamei） farming pond,our study investigated plankton community composition,water quality indicators and growth indicators in two shrimp farming ponds（ only shrimp in early stage,two months later adding Cirrhinus molitorella to the farming ponds）. The results showed that the concentrations of total nitrogen,ammonia nitrogen,nitrate and nitrite in the polyculture ponds were significantly lower than those in the monoculture ponds（ P 〈0. 05）,but the phosphate content was significantly higher（ P 〈0. 05）. The shrimp yields of the polyculture ponds were higher than those in the monoculture ponds. A total of 6 phylum and 46 species of phytoplankton were detected before polyculture,and a total of 6 phylum and 44 species after polyculture. Density and biomass of phytoplankton before and after polyculture were 167. 32 × 10~6 cells/L,7. 84 mg/L and 53. 69 × 106 cells/L,4. 24 mg/L,respectively. A total of 4 phylum and 23 spe-cies of zooplankton were detected before polyculture,and a total of 4 phylum and 17 species were detected after polyculture. Density and biomass of zooplankton before and after polyculture were 3 014. 6 ind./L,3. 981 mg/L and 1 201. 65 ind./L,0. 968 mg/L,respectively. The diversity index of phytoplankton increased,but the diversity index of zooplankton decreased in polyculture ponds. The results indicated that the concentrations of the total nitrogen,ammonia nitrogen and the biomass of plankton were reduced,the phytoplankton diversity was improved,the balance of microalgae was promoted,which helped to improve the yield of shrimp.