虾稻综合种养系统浮游动物群落结构及其与环境因子的关系

为探究虾稻综合种养(integrated crayfish-rice co-culture,ICRC)系统浮游动物的群落结构特征及其主要影响因素,对潜江市典型ICRC稻田渔沟和田面水体的浮游动物进行了季度研究,并分析了浮游动物和浮游植物、水体理化因子之间的相关性。结果显示:(1)共采集浮游动物60种,分别包含原生动物、轮虫、枝角类和桡足类12、28、10、10种(属),其中,优势类群为剑水蚤目无节幼体、桡足幼体以及蚤状溞(Daphnia pulex);Shannon-Wiener指数、Margalef指数和Pielou指数的年均值分别为1. 48、3. 42和0. 55;(2)浮游动物密度和生物量的变化范围分别为7. 65～1309. 50 ind./L、0. 08～50. 04 mg/L,年均值分别为360. 0 ind./L、17. 45 mg/L,桡足类和枝角类在密度和生物量上均占有绝对优势;(3)浮游动物物种数、多样性指数(田面除外)、密度和生物量均表现出明显的季节差异,其中密度和生物量在春季显著最高,相关性分析表明浮游动物物种数和资源量主要受总磷、浮游植物密度与生物量的影响;(4)浮游动物的物种数、多样性、密度和生物量在渔沟和田面两种生境间无明显差异。本研究表明ICRC系统中有丰富的大型浮游动物资源未得到利用,同时鉴于浮游动物可作为小龙虾早期生活史阶段的食物来源,需进一步研究秋冬季浮游动物变化,以及如何培育和合理利用此阶段的浮游动物以促进幼虾生长、提高存活率。

Community structure of zooplankton and its relationship with environmental factors in integrated crayfish-rice co-culture system

To understand the zooplankton community structure and its relationship with environmental factors in the integrated crayfish-rice co-culture (ICRC) system, the species, density and biomass of zooplankton were quarterly investigated in both the trench and rice paddy in four typical ICRC fields in Qianjiang City, China, and the relation of zooplankton to 6 water factors and phytoplankton were analyzed. The main results showed that: (1) There were 60 species in the ICRC system, which included 12, 28, 10 and 10 species of Protozoa, Rotifera, Cladocera and Copepoda, respectively. The dominant taxa were Cyclopoida copepodite, nauplius and Daphnia pulex. The annual mean values of the Shannon-Wiener index, Margalef index and Pielou index were 1.48, 3.42 and 0.55, respectively. (2) The ranges of zooplankton density and biomass were 7.65-1 309.50 ind./L and 0.08-50.04 mg/L, respectively, with annual average values of 360.0 ind./L and 17.45 mg/L, respectively, and Cladocera and Copepoda were the absolutely dominant groups. (3) The number of species, diversity indexes (excepting at rice paddy), density and biomass of zooplankton showed significant seasonal differences, with significantly highest density and biomass in spring, and the Pearson correlation analysis showed that species number, density and biomass of zooplankton were significantly correlated to total phosphorus content, and density and biomass of phytoplankton. (4) There was no significant difference between the trench and rice paddy for any of the indicators of species number, diversity, density and biomass of zooplankton. These results indicate that there is plentiful and unutilized large zooplankton in ICRC system. And as zooplankton is an important food item for the early life history stage of crayfish, zooplankton and its influencing factors in autumn and winter, and how to cultivate and use zooplankton at this stage to promote the growth and survival of juvenile crayfish, should be further studied.