稻虾共作水体浮游植物群落结构特征分析

为认识稻虾共作水体浮游植物群落结构特征, 于2016年4月至12月对江汉平原4处稻虾共作水体浮游植物和理化因子开展了逐月调查与分析。共鉴定出浮游植物7门124种, 其中绿藻78种、蓝藻16种、硅藻15种、裸藻3种、隐藻2种、甲藻7种、金藻3种。6—9月浮游植物的种类数、细胞密度、叶绿素a含量达到最大值, 最小值出现在12月份; 浮游植物细胞密度波动范围在1.37×105—2.93×108 cells/L, 叶绿素a含量的变化范围为0.15—208.60 μg/L。调查期间浮游植物的优势种共28种, 主要优势种有颤藻、蓝纤维藻、微囊藻、小球藻、隐藻等。浮游植物Shannon-Wiener多样性指数周年变化范围为0.64—6.3, 多样性指数最高出现在10月份, 最低出现在8月份。结果显示, 稻虾共作水体浮游植物群落结构较复杂, 细胞密度变化显示时空的一致性, 优势种组成以及优势度存在明显的空间差异(P<0.05), 稻田的浅水环境以及小龙虾的养殖行为显著影响浮游植物群落的结构。鉴于藻类作为初级生产者对于水生态环境和小龙虾健康具有重要作用, 关注种养结合水体中藻类群落的演变规律对于保障稻田种养的综合效益具有积极意义。

CHARACTERISTICS OF COMMUNITY STRUCTURE OF PHYTOPLANKTON IN THE INTEGRATED RICE-CRAYFISH SYMBIOSIS FARMING SYSTEM

Jianghan Plain is an alluvial plain located in the middle and south of Hubei province, China. In order to explore the community structure of phytoplankton in an integrated rice-crayfish symbiosis farming (IRCSF) system, algal species, cell density, algal biomass, and physicochemical factors in four rice-crayfish symbiosis farming water bodies were monthly investigated in the Jianghan Plain from April 2016 to December 2016. There were 124 species belonged to 7 phylum, which observed in this integrated system; 78 species belonged to Chlorophyta; 16 species belonged to Cyanophyta; 15 species belonged to Bacillariophyta; 3 species belonged to Euglenophyta; 2 species belonged to Cryptophyta; 7 species belonged to Pyrrophyta; and 3 species belonged to Chrysophyta. The number of algal species, cell density value, and chlorophyll-a content all reached the maximum value from June to September, while the minimum value appeared in December. Algal cell density fluctuated in the range of 1.37×105 to 2.93×108 cells/L, and the content of chlorophyll-a varied from 0.15 to 208.60 μg/L. During the study period, 28 dominant species were totally identified. The dominant species were Oscillatoria, Dactyloccocpsis, Microcystis, Chlorella, and Cryptomonas. The annual variation of the Shannon-Wiener diversity index was from 0.64 to 6.3. The maximum value of diversity index achieved in October, while the minimum value was in August. The results showed that the community structure of phytoplankton in the IRCSF sytem was complex with an obvious spatio-temporal heterogeneity. Since algae plays an important role in water environment and crayfish cultivation, it is of great significance to pay attention to the change of community structure of phytoplankton in the IRCSF system.