Abstract: The physicochemical environment and phytoplankton species composition and density in 9 Macrobrachium nipponense mid-cultured waters in Siyang City, Jiangsu Province were analyzed through sampling on July 12, 2018, and the effects of different culture modes on culture environment were compared. Results showed dissolve oxygen (DO, > 8.44 mg/L) and pH (7.91 ~ 9.26) were relatively high, while total nitrogen (TN, 1.030 ~ 1.571 mg/L), total phosphorus (TP, 0.174 ~ 0.421 mg/L) and chemical oxygen demand (CODMn, 4.39 ~ 8.16 mg/L) were low in the Macrobrachium nipponense cultured waters. A total of 64 genus/species of phytoplankton were observed in the cultured waters, and most of them were species belonged to Cyanophyta and Chlorophyta. The diversity index of phytoplankton was high and the community structure was stable. The density of phytoplankton was 0.06 ×108 ~ 3.06 ×108 cells/L. Results of RDA showed that water temperature, NO2--N and CODMn were the main environmental factors influencing the density of dominant phytoplankton in the Macrobrachium nipponense cultured waters. Different species of mixed culture have certain influence on the physicochemical indexes and phytoplankton in the Macrobrachium nipponense cultured waters, but the influence of management mode on environmental factors is more significant. Since the concentrations of pH and Ca2+ in the investigated Macrobrachium nipponense cultured waters were lower than the growth-optimizing values, and high concentrations of TP and CODMn promoted the outbreaking of cyanobacterial bloom, it is recommended to apply appropriate quicklime to increase the concentrations of pH and Ca2+, and take necessary steps to control the increasing of TP and CODMn in the cultured waters.

Key words: Macrobrachium nipponense, species of mixed culture, culture mode, physicochemical environment, phytoplankton

摘要： 2018年7月12日采样分析江苏省泗阳县9处青虾（Macrobrachium nipponense）养殖中期水体的理化环境、浮游植物种类组成和密度，并比较不同养殖模式对养殖环境的影响。结果显示：青虾养殖水体中，溶氧（DO）> 8.44 mg/L、pH 7.91 ~ 9.26、总氮（TN）1.030 ~ 1.571 mg/L、总磷（TP）0.174 ~ 0.421 mg/L、高锰酸钾指数（CODMn）4.39 ~ 8.16 mg/L，说明青虾养殖水体具有DO和pH较高，N、P及有机质较低的特点。养殖水体内共观察到浮游植物64属/种，以蓝藻和绿藻为主，浮游植物多样性指数较高，群落结构较稳定；浮游植物密度为0.06×108 ~ 3.06×108个/L。RDA分析显示，水温、亚硝酸盐（NO2--N）和CODMn是影响青虾养殖水体中优势浮游植物密度的主要环境因子。不同混养种类对青虾养殖水体理化指标和浮游植物具有一定的影响，但管理模式对环境因子的影响更显著。鉴于所调查的青虾养殖水体内pH和Ca2+质量浓度低于青虾生长最适值及TP和CODMn质量浓度升高会增加蓝藻水华暴发的风险，建议适当施加生石灰来提高养殖水体中的pH和Ca2+质量浓度，并采取必要措施来控制养殖水体中TP和CODMn的增加。

关键词: 青虾, 混养种类, 养殖模式, 理化环境, 浮游植物