Conditions in freshwater ecosystems are responsible for maintaining biodiversity and other ecosystem services. Identifying and understanding how anthropogenic disturbances affect biotic conditions are important steps in rehabilitating and protecting environmental quality. The relative risk, relative extent, and attributable risk approaches are used to determine ecosystem conditions in ecological monitoring programs conducted across large spatial extents. Our study was conducted in the Pandeiros River basin, which is a protected area in Minas Gerais, Brazil, that contains 233 km of mapped streams that were perennial and accessible. Field sampling was conducted in the dry period (April and June 2016) at 40 randomly selected sites. Ten multimetric indices (MMIs), previously determined to be sensitive in this river basin, were calculated. All the physical habitat disturbance metrics were significantly correlated with the MMIs. The risk of finding poor MMI scores was 1.6–1.7 times higher at sites with a high integrated disturbance index (IDI) or local disturbance index (LDI) score. Pasture was the most extensive disturbance, affecting 40.8% of the stream length, followed by 40.1% for low bed stability, 29% for fine substrates (<16 mm), 24.4% for high IDI scores, and 21.7% for high LDI scores. This is useful to know for five reasons: (1) standardized MMIs can assess environmental quality. (2) MMIs clarify that both catchment and local disturbances may represent serious risks to aquatic assemblages. (3) MMIs indicate which disturbances represent the most risk by comparing MMI scores against disturbance scores. (4) MMI risk assessments facilitate choosing the most appropriate mitigation actions. (5) Our results suggest environmental conservation actions for similar river basins.

中文翻译：

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新热带稀树草原河流域水生生物条件的主要风险

淡水生态系统的条件负责维持生物多样性和其他生态系统服务。识别和理解人为干扰如何影响生物条件是恢复和保护环境质量的重要步骤。相对风险、相对范围和可归因风险方法用于确定跨大空间范围进行的生态监测计划中的生态系统条件。我们的研究是在 Pandeiros 河流域进行的，该流域是巴西米纳斯吉拉斯州的一个保护区，其中包含 233 公里长且常年可到达的地图河流。在旱季（2016 年 4 月和 6 月）在 40 个随机选择的地点进行了现场采样。计算了之前确定在该流域敏感的十个多指标 (MMI)。所有的物理栖息地干扰指标都与 MMI 显着相关。在综合干扰指数 (IDI) 或局部干扰指数 (LDI) 评分较高的地点，发现 MMI 评分较差的风险要高 1.6-1.7 倍。牧场是最广泛的干扰，影响了 40.8% 的河流长度，其次是 40.1% 的低床稳定性、29% 的细基质（<16 毫米）、24.4% 的高 IDI 分数和 21.7% 的高 LDI 分数。了解这一点很有用，原因有以下五个：(1) 标准化的 MMI 可以评估环境质量。(2) MMI 澄清流域和局部干扰都可能对水生组合构成严重风险。(3) MMI 通过将 MMI 分数与干扰分数进行比较来表明哪些干扰代表的风险最大。(4) MMI 风险评估有助于选择最合适的缓解措施。(5) 我们的研究结果表明了类似流域的环境保护行动。