Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou 510006, China.
Swift Current Research and Development Centre, Agriculture & Agri-Food Canada, Swift Current, SK, Canada.
Sci Total Environ. 2021 Apr 10;764:142840. doi: 10.1016/j.scitotenv.2020.142840. Epub 2020 Oct 9.
Protists in aquaculture ponds are key components associated with primary productivity, nutrient cycling, and fish healthy. However, the protist metacommunity diversity, as well as the ecological and environmental factors that structure protist metacommunity in aquaculture ponds remain poorly understood. This study examined protist metacommunities in water and sediment of larval, small juvenile and large juvenile grass carp ponds. The results indicated sediment resuspension became stronger with the increased fish size, which led to high levels of total suspended solids and nitrogen but low levels of phosphate, chlorophyll a and transparency in water. Moreover, sediment resuspension subsequently increased the alpha diversity indexes (i.e., OTU number, Shannon index and Simpson index) of protist communities in water and sediment. Meanwhile, sediment resuspension increased the relative abundance of heterotrophic Ciliophora and Cercozoa, but decreased the relative abundance of autotrophic Chlorophyta, Stramenopiles X, and Ochrophyta. Besides, some mixotrophic and heterotrophic protists showed competitive advantages in the turbidity water, which led to the increase of negative interactions in the protist co-occurrence networks. Based on the null model, sediment resuspension strengthened homogeneous selection (deterministic process) and weakened dispersal limitation (stochastic process) processes of protist community assembly. Indeed, protist community dissimilarity within each local community and each habitat (water or sediment) both decreased while the community dissimilarity between habitats increased with the increase of fish size. Therefore, sediment resuspension did not enhance the dispersal path between water and sediment, but decreased the dispersal limitation within sediment and water coupled with the strengthening of environmental selection. These results indicated that grass carp could restructure the protist metacommunity in aquaculture ponds through bottom up way of sediment resuspension. This study advances our understanding of the relationship between fish and protist metacommunity assembly in aquaculture systems.
水产养殖池塘中的原生动物是与初级生产力、养分循环和鱼类健康相关的关键组成部分。然而，原生动物后生动物群的多样性，以及构成水产养殖池塘原生动物后生动物群的生态和环境因素仍知之甚少。本研究调查了草鱼幼鱼、小稚鱼和大稚鱼池水中和底泥中的原生动物后生动物群。结果表明，随着鱼类个体的增大，底泥再悬浮作用增强，导致水体中总悬浮物和氮含量升高，而磷、叶绿素 a 和透明度降低。此外，底泥再悬浮作用增加了水和底泥中原生动物群落的 alpha 多样性指数（即 OTU 数量、香农指数和辛普森指数）。同时，底泥再悬浮作用增加了异养纤毛虫和肉足虫的相对丰度，而降低了自养绿藻、甲藻 X 和黄藻的相对丰度。此外，一些混合营养和异养原生动物在浊度水中具有竞争优势，导致原生动物共生网络中的负相互作用增加。基于零模型，底泥再悬浮作用增强了原生动物群落组装的同质性选择（确定性过程），并减弱了扩散限制（随机过程）。事实上，随着鱼类个体的增大，每个局部群落和每个生境（水或底泥）内的原生动物群落相似性降低，而生境之间的群落相似性增加。因此，底泥再悬浮作用并没有增强水和底泥之间的扩散路径，而是降低了底泥和水内的扩散限制，同时增强了环境选择。这些结果表明，草鱼通过底泥再悬浮作用的底向上方式可以重塑水产养殖池塘中的原生动物后生动物群。本研究增进了我们对水产养殖系统中鱼类和原生动物后生动物群组装之间关系的理解。
