State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.
College of Life Sciences, Zaozhuang University, Zaozhuang, 277160, China.
Sci Rep. 2017 Jun 23;7(1):4134. doi: 10.1038/s41598-017-04445-7.
Although human disturbance indirectly influences lotic assemblages through modifying physical and chemical conditions, identifying thresholds of human disturbance would provide direct evidence for preventing anthropogenic degradation of biological conditions. In the present study, we used data obtained from tributaries of the Three Gorges Reservoir in China to detect effects of human disturbance on streams and to identify disturbance thresholds for benthic diatoms. Diatom species composition was significantly affected by three in-stream stressors including TP, TN and pH. Diatoms were also influenced by watershed % farmland and natural environmental variables. Considering three in-stream stressors, TP was positively influenced by % farmland and % impervious surface area (ISA). In contrast, TN and pH were principally affected by natural environmental variables. Among measured natural environmental variables, average annual air temperature, average annual precipitation, and topsoil % CaCO, % gravel, and total exchangeable bases had significant effects on study streams. When effects of natural variables were accounted for, substantial compositional changes in diatoms occurred when farmland or ISA land use exceeded 25% or 0.3%, respectively. Our study demonstrated the rationale for identifying thresholds of human disturbance for lotic assemblages and addressed the importance of accounting for effects of natural factors for accurate disturbance thresholds.
尽管人类干扰通过改变物理和化学条件间接影响流水生物群落，但确定人类干扰的阈值将为防止人为生物条件退化提供直接证据。在本研究中，我们使用中国三峡水库支流的数据来检测溪流中人类干扰的影响，并确定底栖硅藻的干扰阈值。硅藻物种组成受到 TP、TN 和 pH 这三个溪流内应激因子的显著影响。硅藻还受到流域农田比例和自然环境变量的影响。考虑到三个溪流内应激因子，TP 受到农田比例和不透水表面面积（ISA）的正影响。相比之下，TN 和 pH 主要受自然环境变量的影响。在所测量的自然环境变量中，年平均空气温度、年平均降水量以及表土的 CaCO3%、砾石%和总可交换碱基对研究溪流有显著影响。当考虑自然变量的影响时，当农田或 ISA 土地利用超过 25%或 0.3%时，硅藻的组成发生了实质性变化。我们的研究证明了确定流水生物群落干扰阈值的合理性，并强调了考虑自然因素影响以确定准确干扰阈值的重要性。
