Griffith Michael B, Lazorchak James M, Herlihy Alan T
National Center for Environmental Assessment, U.S. Environmental Protection Agency, 26 W. Martin Luther King Drive, Cincinnati, Ohio 45268, USA.
Environ Toxicol Chem. 2004 Jul;23(7):1786-95. doi: 10.1897/03-408.
If bioassessments are to help diagnose the specific environmental stressors affecting streams, a better understanding is needed of the relationships between community metrics and ambient criteria or ambient bioassays. However, this relationship is not simple, because metrics assess responses at the community level of biological organization, while ambient criteria and ambient bioassays assess or are based on responses at the individual level. For metals, the relationship is further complicated by the influence of other chemical variables, such as hardness, on their bioavailability and toxicity. In 1993 and 1994, U.S. Environmental Protection Agency (U.S. EPA) conducted a Regional Environmental Monitoring and Assessment Program (REMAP) survey on wadeable streams in Colorado's (USA) Southern Rockies Ecoregion. In this ecoregion, mining over the past century has resulted in metals contamination of streams. The surveys collected data on fish and macroinvertebrate assemblages, physical habitat, and sediment and water chemistry and toxicity. These data provide a framework for assessing diagnostic community metrics for specific environmental stressors. We characterized streams as metals-affected based on exceedence of hardness-adjusted criteria for cadmium, copper, lead, and zinc in water; on water toxicity tests (48-h Pimephales promelas and Ceriodaphnia dubia survival); on exceedence of sediment threshold effect levels (TELs); or on sediment toxicity tests (7-d Hyalella azteca survival and growth). Macroinvertebrate and fish metrics were compared among affected and unaffected sites to identify metrics sensitive to metals. Several macroinvertebrate metrics, particularly richness metrics, were less in affected streams, while other metrics were not. This is a function of the sensitivity of the individual metrics to metals effects. Fish metrics were less sensitive to metals because of the low diversity of fish in these streams.
如果生物评估要有助于诊断影响溪流的特定环境压力源，就需要更好地理解群落指标与环境标准或环境生物测定之间的关系。然而，这种关系并不简单，因为指标评估的是生物组织群落层面的反应，而环境标准和环境生物测定评估的是个体层面的反应或基于个体层面的反应。对于金属而言，其他化学变量（如硬度）对其生物有效性和毒性的影响使这种关系更加复杂。1993年和1994年，美国环境保护局（U.S. EPA）对美国科罗拉多州南落基山生态区的可涉渡溪流开展了一项区域环境监测与评估计划（REMAP）调查。在这个生态区，过去一个世纪的采矿活动导致溪流受到金属污染。这些调查收集了鱼类和大型无脊椎动物群落、物理栖息地以及沉积物和水化学及毒性方面的数据。这些数据为评估特定环境压力源的诊断性群落指标提供了一个框架。我们根据水中镉、铜、铅和锌的硬度调整标准超标情况、水毒性测试（48小时黑头呆鱼和大型蚤存活情况）、沉积物阈值效应水平（TELs）超标情况或沉积物毒性测试（7天墨西哥高原钩虾存活和生长情况），将溪流表征为受金属影响的溪流。比较了受影响和未受影响站点之间的大型无脊椎动物和鱼类指标，以确定对金属敏感的指标。在受影响的溪流中，一些大型无脊椎动物指标，特别是丰富度指标较低，而其他指标则不然。这是各个指标对金属影响敏感性的一种体现。由于这些溪流中鱼类多样性较低，鱼类指标对金属的敏感性较低。
