School of Biological Sciences, University of Western Australia, Perth, WA, 6009, Australia.
Centre for Natural Resource Management, University of Western Australia, Albany, WA, 6330, Australia.
Environ Monit Assess. 2024 Jun 3;196(7):592. doi: 10.1007/s10661-024-12734-8.
Freshwater aquatic ecosystems are threatened globally. Biological monitoring is required to deliver rapid and replicable assessment of changes in habitat quality. The Ephemeroptera, Plectoptera, Trichoptera (EPT) index is a globally recognised rapid bioassessment that measures taxa richness of three insect orders whose larvae are considered sensitive to freshwater habitat degradation. South-western Australia contains threatened freshwater ecosystems but has depauperate EPT fauna and high endemism, potentially reducing the capacity of the EPT index to track degradation. This study investigated if EPT species richness, composition or individual species tracked physical or chemical river degradation in three catchments in south-western Australia. We sampled EPT fauna and measured water chemistry, erosion, sedimentation, riparian vegetation cover and instream habitat at 98 sites in the winters of 2007 and 2023. We found 35 EPT taxa across the study area with a median number of species per site of two. EPT species richness had weak positive associations with a composite water quality index and dissolved oxygen and weak negative associations with electrical conductivity and total nitrogen. No association was found between physical and fringing zone degradation measures and EPT species richness. EPT community structure generally did not distinguish between sites with high or low degradation levels. The presence of the mayfly Nyungara bunni tracked salinity, dissolved oxygen and nitrogen levels, but its usefulness as a bioindicator could be limited by its restricted range. This study suggests that the EPT index would need modification or combination with other indices to be a useful rapid bioassessment in south-western Australia.
淡水水生生态系统在全球范围内受到威胁。需要进行生物监测，以便快速、可重复地评估生境质量的变化。蜉蝣目、石蝇目、毛翅目（EPT）指数是一种全球公认的快速生物评估方法，它衡量了三个昆虫目（其幼虫被认为对淡水生境退化敏感）的分类丰富度。澳大利亚西南部拥有受威胁的淡水生态系统，但 EPT 动物群贫乏，特有种丰富，这可能降低了 EPT 指数跟踪退化的能力。本研究调查了在澳大利亚西南部的三个集水区中，EPT 物种丰富度、组成或单个物种是否跟踪了物理或化学河流退化。我们在 2007 年和 2023 年的冬季在 98 个地点采样了 EPT 动物群，并测量了水化学、侵蚀、沉降、河岸植被覆盖和溪流栖息地。我们在研究区域内发现了 35 种 EPT 类群，每个地点的中位数物种数为 2 种。EPT 物种丰富度与综合水质指数和溶解氧呈弱正相关，与电导率和总氮呈弱负相关。物理和边缘区退化措施与 EPT 物种丰富度之间没有关联。EPT 群落结构通常不能区分高退化水平和低退化水平的地点。蜉蝣 Nyungara bunni 的存在与盐度、溶解氧和氮水平有关，但由于其分布范围有限，其作为生物指标的有用性可能受到限制。本研究表明，EPT 指数需要修改或与其他指数结合使用，才能成为澳大利亚西南部有用的快速生物评估方法。
