Department of Biology, Aarhus University, Ole Worms Allé 1, 8000 Aarhus, Denmark.
Department of Health and Environmental Sciences, Xi'an Jiaotong-Liverpool University, Suzhou 215123, China.
Sci Total Environ. 2020 Nov 15;743:140720. doi: 10.1016/j.scitotenv.2020.140720. Epub 2020 Jul 5.
Despite increasing interest in hydrological effects on riverine ecosystems, few studies have documented the impact of hydrology on biofilm community functions, and those existing have typically focused on annual-based hydrological indices. In this study, we conducted monthly samplings during a year in five lowland streams with different flow regimes and investigated the impacts of hydrological conditions and physico-chemical variables on the trait composition of diatoms growing on artificial substrates, biomass (chlorophyll a and ash free dry weight), and biofilm community functions (biochemical processes, i.e., biofilm metabolism and nutrient uptake rates measured in the laboratory). Instead of the commonly used annual-based hydrological indices, we calculated indices for shorter periods (14 and ~28 days) of the hydrological regimes. Results of species-based variation partitioning showed that short-period hydrological indices (10.10 ± 7.18%) contributed more to explain species distribution than physico-chemical variables (5.90 ± 3.83%), indicating the dominant role of hydrology in structuring the diatom community. Specifically, we found different response patterns for different guilds and size classes to the hydrological and physico-chemical variables, and our results demonstrated that species tolerating high disturbance may be more appropriate as indicators of environmental disturbance than low-tolerant species. We also found dominant effects of short-period hydrological events on biomass and biofilm community functions. Despite an overall negative effect of high flow events and flow variations on biomass and biofilm community functions, positive effects on function-biomass ratios were also observed, indicating that the effects of flow regimes on biofilm are complex. In conclusion, our study highlights the importance of including short-period hydrological conditions in studies on environmental factors shaping benthic algae. Based on our results, we recommend use of short-period hydrological conditions when investigating the effects of flow regime on biofilm community composition and functions.
尽管人们对水文对河流生态系统的影响越来越感兴趣，但很少有研究记录水文对生物膜群落功能的影响，而且现有的研究通常侧重于基于年度的水文指标。在这项研究中，我们在五个具有不同水流模式的低地溪流中进行了为期一年的每月采样，并调查了水文条件和理化变量对人工基质上生长的硅藻特征组成、生物量（叶绿素 a 和无灰干重）以及生物膜群落功能（生化过程，即实验室测量的生物膜代谢和养分吸收速率）的影响。我们没有使用常用的基于年度的水文指标，而是计算了较短时间（14 天和~28 天）的水文模式指标。基于物种的变异分解结果表明，短时间水文指标（10.10±7.18%）比理化变量（5.90±3.83%）对物种分布的解释贡献更大，这表明水在塑造硅藻群落方面起着主导作用。具体来说，我们发现不同的 guild 和大小类群对水文和理化变量的反应模式不同，我们的结果表明，与低耐受物种相比，耐受高干扰的物种可能更适合作为环境干扰的指标。我们还发现短时间水文事件对生物量和生物膜群落功能有主导作用。尽管高流量事件和流量变化对生物量和生物膜群落功能有总体负面影响，但也观察到对功能-生物量比的正效应，这表明水流模式对生物膜的影响是复杂的。总之，我们的研究强调了在研究塑造底栖藻类的环境因素时纳入短时间水文条件的重要性。基于我们的结果，我们建议在研究水流模式对生物膜群落组成和功能的影响时，使用短时间水文条件。
