浙江青田稻鱼共生系统浮游动物和大型底栖动物的群落结构特征及动态分析

Study on community structure and seasonal dynamics of zooplankton and macrobenthos in Rice-Fish Symbiotic System in Qingtian, Zhejiang Province

摘要:

目的 揭示浙江青田稻鱼共生系统 (世界重要农业文化遗产)中浮游动物和大型底栖动物的群落结构特征、动态以及鱼类引入的影响。方法 实验在2020年12月和2021年4、7、9月对当地的稻-田鱼田、稻-马口鱼田和水稻单作田的浮游动物和大型底栖动物进行调查采样，鉴定、统计和分析该系统中浮游动物和大型底栖动物的种类组成、密度、生物量、优势种及相关多样性指数。结果 通过4个季节的调查，共鉴定出浮游动物2门30种和大型底栖动物3门9种。浮游动物包括轮虫16种、枝角类7种、桡足类6种，其中近邻剑水蚤、中型小剑水蚤、萼花臂尾轮虫为全年优势种，平突船卵溞、光滑平直溞和大肚须足轮虫为季节性优势种。大型底栖动物包括寡毛类2种、摇蚊3种、腹足类3种，其中全年3种优势种为苏氏尾鳃蚓，霍普水丝蚓和黄色羽摇蚊。在4次调查取样期间，稻-田鱼、稻-马口鱼及水稻单作田这三类稻田系统中浮游动物的香农-威纳指数 (H′₁)、辛普森多样性指数 (D₁)和Pielou均匀度指数 (J′₁)的变化范围分别为2.9~4.1、0.81~0.93和0.67~0.93。浮游动物两种多样性指数的最高值在稻-田鱼和稻-马口鱼田中均出现在水稻移栽前 (4月)，水稻单作田中则出现在水稻扬花期 (9月)；其最低值在稻-田鱼和稻-马口鱼田中均出现在水稻成熟收割前 (12月)，水稻单作田则在水稻拔节期 (7月)。三类稻田的浮游动物Pielou均匀度指数均在水稻移栽前最高，成熟收割前最低。三类稻田系统中大型底栖动物的香农-威纳指数 (H′₂)、辛普森多样性指数 (D₂)和Pielou均匀度指数 (J′₂)的变化范围分别为1.46~2.24、0.56~0.77和0.52~0.75。大型底栖动物两种多样性指数的峰值在三类稻田中均出现在水稻扬花期；在稻-田鱼和稻-马口鱼田中其最低值出现在水稻移栽前，水稻单作田的最低值则在水稻拔节期。大型底栖动物Pielou均匀度指数的峰值在稻-田鱼田中出现在水稻扬花期，稻-马口鱼和水稻单作田均在成熟收割前；在稻-田鱼和稻-马口鱼田中其最低值均出现在水稻移栽前，但水稻单作田最低值在拔节期。结论 青田稻鱼系统浮游动物和大型底栖动物的种类、密度、生物量及相关多样性指数在不同季节存在显著差异；同一采样时期，浮游动物和大型底栖动物的密度、生物量在两类养鱼稻田之间均无显著差异；养鱼稻田浮游动物和大型底栖动物的密度、生物量均低于水稻单作田，但差异不显著。了解稻鱼共生系统浮游动物和大型底栖动物群落结构及其季节动态，有助于揭示稻-鱼互利共生的机制，为稻渔综合种养模式的改进和发展提供理论依据。

Abstract:

Zooplanktons and macrobenthos are key consumers and decomposers in the rice-fish complex ecosystem and serve as important natural food sources for fish. To investigate the effects of fish on the Rice-Fish Symbiosis System in Qingtian, Zhejiang Province—recognized as the Globally Important Agricultural Heritage System by the FAO in 2005—we examined the community structure and seasonal dynamics of zooplankton and macrobenthos in rice paddy. Specifically, we compared these communities in three types of rice paddies: rice-carp field (RC), rice-Chinese hooksnout carp fields (RCHC), and rice fields without fish (RWF) during December 2020 and April, July and September 2021. Our results identified 30 species of zooplankton (including 16 species of rotifers, 6 species of cladocerans and 7 species of copepods) and 10 macrobenthos species (including 2 oligochaetes species, 3 chironomids species, and 3 gastropods species). In zooplankton communities, Cyclops vicinus, Microcyclops intermedius, and Brachionus calyciflorus were dominant throughout the year, while Scapholeberis mucronata, Pleuroxus laevis, and Euchlanis dilatata were seasonal dominants. In macrobenthos, Branchiura sowerbyi, Limnodrilus hoffmeisteri, and Chironomus flaviplumus were dominant species throughout the year. The Shannon-Weiner index (H′₁), Simpson diversity index (D₁), and the Pielou evenness index (J′₁) of zooplankton in the three rice paddy systems ranged from 2.9-4.1, 0.81-0.93 and 0.52-0.75, respectively. The highest H′₁ and D₁ in RC and RCHC occurred in April, while in RWF, they peaked in September. Conversely, the lowest values in RC and RCHC appeared in December, and in RWF in July. The J′₁ were the highest in April and lowest in December across all paddy types. For macrobenthos, the Shannon-Weiner index (H′₂), Simpson diversity index (D₂) and Pielou evenness index (J′₂) varied from 1.46-2.24, 0.56-0.77 and 0.52-0.75, respectively. The H′₂ and D₂ peaks occurred in September for all three paddy types, while the lowest values in RC and RCHC appeared in April and in RWF in July. The J′₂ peaked in September in RC, and in December in RCHC and RWF, with the lowest values appearing in April for RC and RCHC and in July for RWF. Our study found that the species richness, density, biomass, and diversity indexes of zooplankton and macrobenthos in the rice-fish system varied significantly across seasons (all P<0.05). With the same season, the density and biomass of zooplankton and macrobenthos in RC and RCHC were lower than in RWF, although these differences were not significant (all P>0.05). In summary, elucidating the community structure and seasonal dynamics of zooplankton and macrobenthos in the rice-fish symbiosis system can help reveal the intrinsic mechanisms of the mutually beneficial relationship between rice and fish. This knowledge can further promote the development and comprehensive improvement of the cropping-breeding coupled mode of rice and fishery.