Department of Life Sciences, Roehampton University, London, UK.
Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Department Ecohydrology, Berlin, Germany.
Sci Rep. 2018 Oct 26;8(1):15871. doi: 10.1038/s41598-018-34206-z.
A current controversy in ecology is whether biological communities are discrete biological entities or simply study units created for convenience; a debate that becomes even more heated when delimiting communities along ecotones. Here, we report an interdisciplinary study designed to address the interplay between environmental drivers and community ecology in a typical ecotone ecosystem: the streambed. Environmental filtering at a micro-scale determined how diversity, productivity and composition of the whole streambed assemblage varied with depth and with the direction of vertical water exchange. Biomass and production decreased with increasing depth, and were lower under upwelling than downwelling conditions. However, the rate at which biomass and production decreased with increasing depth differed significantly for different taxonomic groups. Using quantitative biocenosis analysis, we also showed that benthic and hyporheic zone assemblages (assemblages in close juxtaposition) could be clearly distinguished as discrete communities with individual integrity. Vertical hydrodynamic conditions also influenced the demarcation between both communities; the benthic community reached greater depths in downwelling than in upwelling zones.
目前生态学领域存在一个争议，即生物群落究竟是离散的生物实体，还是仅仅是为了方便研究而创建的单位；而当沿着生态交错带来划分群落时，这个争议就变得更加激烈了。在这里，我们报告了一项跨学科研究，旨在解决典型生态交错带生态系统——河床——中环境驱动因素和群落生态学之间的相互作用。微尺度的环境过滤决定了整个河床生物群落在深度和垂直水交换方向上的多样性、生产力和组成如何变化。生物量和生产力随着深度的增加而减少，上升流条件下的生物量和生产力低于下降流条件下的生物量和生产力。然而，不同分类群的生物量和生产力随深度增加而减少的速度有显著差异。我们还使用定量生物群落分析表明，底栖区和渗流区生物群（紧密相邻的生物群）可以被清楚地区分为具有个体完整性的离散群落。垂直水动力条件也影响了这两个群落之间的划分；在下降流区，底栖群落的深度比上升流区更大。
