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首页> 外文期刊>Freshwater science >Linking land use, in-stream stressors, and biological condition to infer causes of regional ecological impairment in streams
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Linking land use, in-stream stressors, and biological condition to infer causes of regional ecological impairment in streams

机译：将土地利用，河流中的压力源和生物条件联系起来，以推断河流中区域生态损害的原因

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We used field-derived data from streams in Nevada, USA, to quantify relationships between stream biological condition, in-stream stressors, and potential sources of stress (land use). We used 2 freshwater macroinvertebrate-based indices to measure biological condition: a multimetric index (MMI) and an observed to expected (O/E) index of taxonomic completeness. We considered 4 categories of potential stressors: dissolved metals, total dissolved solids, nutrients, and flow alteration. For physicochemical factors that varied predictably across natural environmental gradients, we quantified potential stress as the site-specific difference between observed (O) and expected (E) levels of each factor (O-Estress). We then used 2 sets of Random Forest models to quantify relationships between: 1) biological condition and potential stressors, and 2) stressor values and land uses. The 2 indices of biological condition were differentially responsive to stressors, indicating that no single measure of biological condition could fully characterize assemblage response to stress. Total dissolved solids (as measured by electrical conductivity [EC]) and metal contamination were the stressors most strongly associated with biological degradation. The most likely sources of these stressors were agriculture, urban development, and mining. Our findings highlight the need to develop EC criteria for streams. Measures of biological condition and stress that account for natural variability should reduce errors of inference and increase confidence in causal analyses. This approach will require development of robust models capable of predicting physical and chemical reference conditions. Causal analyses for individual sites require appropriate hypotheses about which stressors and what levels of stress can cause biological degradation. Our study demonstrates the usefulness of field data collected from multiple sites within a region for developing these hypotheses.
机译：我们使用了来自美国内华达州河流的田间数据，以量化河流生物状况，河流内压力源和潜在压力源（土地利用）之间的关系。我们使用了两个基于淡水大型无脊椎动物的指数来衡量生物状况：多指标指数（MMI）和分类完整性的观测到预期（O / E）指数。我们考虑了4类潜在的压力源：溶解金属，总溶解固体，养分和流量变化。对于在自然环境梯度中可预测地变化的物理化学因素，我们将潜在压力量化为每个因素（O-Estress）的观测（O）和预期（E）水平之间的位点差异。然后，我们使用了两组随机森林模型来量化：1）生物条件和潜在压力源，以及2）压力源值和土地利用之间的关系。生物学条件的2个指标对应激源的响应不同，表明没有单一的生物学条件度量可以完全表征组合对应激的响应。总溶解固体（通过电导率[EC]衡量）和金属污染是与生物降解最密切相关的压力源。这些压力的最可能来源是农业，城市发展和采矿。我们的发现强调了需要制定流的EC标准。解释自然可变性的生物学条件和压力的测量应减少推断误差并增加因果分析的置信度。这种方法将需要开发能够预测物理和化学参考条件的鲁棒模型。对单个位置进行因果分析需要适当的假设，以了解哪些压力源以及什么水平的压力会导致生物降解。我们的研究表明，从一个区域内多个站点收集的现场数据对于发展这些假设很有用。

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