Data from: Recovery of a mining-damaged stream ecosystem

This paper presents a 30+ year record of changes in benthic macroinvertebrate communities and fish populations associated with improving water quality in mining-influenced streams. Panther Creek, a tributary to the Salmon River in central Idaho, USA suffered intensive damage from mining and milling operations at the Blackbird Mine that released copper (Cu), arsenic (As), and cobalt (Co) into tributaries. From the 1960s through the 1980s, no fish and few aquatic invertebrates could be found in 40 km of mine-affected reaches of Panther Creek downstream of the metals contaminated tributaries, Blackbird and Big Deer Creeks. Efforts to restore water quality began in 1995, and by 2002 Cu levels had been reduced by about 90%, with incremental declines since. Rainbow Trout (Oncorhynchus mykiss) were early colonizers, quickly expanding their range as areas became habitable when Cu concentrations dropped below about 3X the U.S. Environmental Protection Agency’s biotic ligand model (BLM) based chronic aquatic life criterion. Anadromous Chinook Salmon (O. tshawytscha) and steelhead (O. mykiss) have also reoccupied Panther Creek. Full recovery of salmonid populations occurred within about 12-years after the onset of restoration efforts and about 4-years after the Cu chronic criteria had mostly been met, with recovery interpreted as similarity in densities, biomass, year class strength, and condition factors between reference sites and mining-influenced sites. Shorthead Sculpin (Cottus confusus) were slower than salmonids to disperse and colonize. While benthic macroinvertebrate biomass has increased, species richness has plateaued at about 70 to 90% of reference despite the Cu criterion having been met for several years. Different invertebrate taxa had distinctly different recovery trajectories. Among the slowest taxa to recover were Ephemerella, Cinygmula and Rhithrogena mayflies, Enchytraeidae oligochaetes, and Heterlimnius aquatic beetles. Potential reasons for the failure of some invertebrate taxa to recover include competition, and high sensitivity to Co and Cu.本研究呈现了一段超过30年的监测记录，记录了受采矿影响的溪流中，随着水质改善而发生的底栖大型无脊椎动物（benthic macroinvertebrate）群落与鱼类种群的变化。美国爱达荷州中部鲑鱼河的支流黑豹溪（Panther Creek）曾因黑鸟矿（Blackbird Mine）的采矿与选矿作业遭受严重破坏，该作业向支流排放了铜（Cu）、砷（As）与钴（Co）。1960年代至1980年代期间，在受金属污染的支流黑鸟溪与大鹿溪下游的40公里受采矿影响的黑豹溪河段中，未发现任何鱼类，仅存在极少量水生无脊椎动物。水质修复工作于1995年启动，至2002年铜浓度已降低约90%，此后浓度仍在逐步下降。虹鳟（Oncorhynchus mykiss）为早期拓殖物种，当铜浓度降至约3倍美国环境保护局（U.S. Environmental Protection Agency）基于生物配体模型（biotic ligand model, BLM）的慢性水生生物基准以下时，适宜栖息地范围扩大，虹鳟的分布范围也随之快速扩张。溯河产卵的奇努克鲑（O. tshawytscha）与钢头鳟（O. mykiss）也已重新进驻黑豹溪。鲑科鱼类种群在修复工作启动后约12年、且铜慢性基准基本达标后约4年实现全面恢复，恢复的判定标准为：对照样点（reference sites）与受采矿影响样点的种群密度、生物量、年组强度以及体质指数均无显著差异。短头杜父鱼（Cottus confusus）的扩散与拓殖速度慢于鲑科鱼类。尽管底栖大型无脊椎动物的生物量有所提升，但即使铜基准已达标多年，其物种丰富度仍停留在对照样点的70%至90%左右，未进一步恢复。不同无脊椎动物类群的恢复轨迹存在显著差异。恢复速度最慢的类群包括Ephemerella属蜉蝣、Cinygmula属蜉蝣、Rhithrogena属蜉蝣，线蚓科（Enchytraeidae）寡毛类动物，以及Heterlimnius属水生甲虫。部分无脊椎动物类群未能恢复的潜在原因包括种间竞争，以及对钴与铜的高敏感性。