The Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.
University of Chinese Academy of Sciences, Beijing, China.
Environ Sci Pollut Res Int. 2022 Oct;29(46):69875-69887. doi: 10.1007/s11356-022-20529-y. Epub 2022 May 17.
Although environmental filtering and spatial structuring are commonly regarded as two key factors shaping community dynamics, their relative contribution remains unknown for numerous aquatic ecosystems, particularly highly dynamic floodplain lakes. This issue is here addressed by examining the seasonal metacommunity dynamics of freshwater fishes in Lake Dongting, a large subtropical lake of the middle Chang-Jiang basin in southern China. Physicochemical variables and fish assemblages were recorded at 20 sampling sites during the wet, normal, and dry seasons. Distance-based redundancy analysis and associated variation partitioning were used to examine the relative role of environmental variables and spatial factors in fish community assembly in each season. Analysis results demonstrated that the relative contribution of environmental filtering and spatial structuring varied depending on environmental features and the extent of hydrological connectivity in different seasons. Intensified physicochemical parameters in the dry season convinced the enhanced environmental filtering, whereas high hydrological connectivity in the wet season favored the stronger spatial process. Specifically, the community assembly processes were temporally dynamic; spatial structuring (or mass effects), resulting from excessively high dispersal rates, was dominant during the flooding season, and environmental filtering was stronger than spatial structuring (or dispersal limitation) during the non-flooding season. These findings highlight the importance of conserving local habitats of Lake Dongting during the dry and normal seasons, and maintaining of the flood pulse of the lake and its natural variability during the wet season. Apparently, the construction of a water-level regulation project at the Chenglingji Channel, the outlet watercourse of Lake Dongting, is not supported because it will change the flood pulse of this lake and thus impact habitat heterogeneity or variability.
虽然环境过滤和空间结构通常被认为是塑造群落动态的两个关键因素，但对于许多水生生态系统，尤其是高度动态的洪泛平原湖泊，其相对贡献仍然未知。本研究通过考察中国中部长江流域亚热带大型湖泊——洞庭湖淡水鱼类的季节集合群落动态，解决了这一问题。在湿季、正常季和干季，在 20 个采样点记录了理化变量和鱼类组合。基于距离的冗余分析和相关的变分分解用于检验环境变量和空间因素在每个季节鱼类群落组装中的相对作用。分析结果表明，环境过滤和空间结构的相对贡献因季节的环境特征和水文连通性程度而异。干季强烈的理化参数促使环境过滤作用增强，而湿季高的水文连通性有利于更强的空间过程。具体而言，群落组装过程是动态的；在洪水季节，由于过度高的扩散率导致的空间结构（或质量效应）占主导地位，而在非洪水季节，环境过滤比空间结构（或扩散限制）更强。这些发现强调了在干季和正常季保护洞庭湖当地生境的重要性，以及在湿季保持湖泊洪水脉冲及其自然变异性的重要性。显然，不支持在城陵矶航道（洞庭湖出水口）建设水位调节工程，因为这将改变该湖泊的洪水脉冲，从而影响栖息地的异质性或变异性。
