Colorado Ecological Services, Western Colorado Field Office, US Fish and Wildlife Service, 445 West Gunnison Ave., Suite 240, Grand Junction, CO, 81501-5711, USA.
, 380 34 Road, Palisade, CO, 81526, USA.
Arch Environ Contam Toxicol. 2019 Jan;76(1):17-30. doi: 10.1007/s00244-018-0566-2. Epub 2018 Sep 26.
Mercury contamination in freshwater fish is widespread across North America, including the western United States. Atmospheric mercury from both natural and manmade emissions deposits into watersheds and, through methylation and biomagnification, accumulates in aquatic food webs. Highest mercury concentrations are found in predatory fish. The endangered Colorado pikeminnow (Ptychocheilus lucius) is a long-lived, top-level piscivore endemic to the Colorado River basin. Mercury exposure to Colorado pikeminnow and another native fish species, the roundtail chub (Gila robusta), was assessed by analyzing muscle tissues collected using a nonlethal technique. Mercury concentrations in Colorado pikeminnow > 400-mm long, captured from critical habitat throughout the species' present range, exceeded the tissue threshold-effect level of 0.2 µg/g wet weight (WW) for whole body fish (0.31 µg/g WW in muscle) recommended to protect fish from injury. Mercury is a neurotoxin and endocrine disruptor, and impacts to fish may include reduced ability to avoid predators, secure food, and reproduce. The highest mercury concentrations were found in both Colorado pikeminnow and roundtail chub collected from the White River, a tributary to the Green River. Colorado pikeminnow from the White and Green rivers had the highest mean mercury concentrations and the lowest mean relative body conditions. Exposure to high mercury concentrations may act in concert with other threatening factors to compromise Colorado pikeminnow population viability and eventual recovery.
北美的淡水鱼中普遍存在汞污染，包括美国西部。来自自然和人为排放的大气汞沉积到流域中，并通过甲基化和生物放大作用，在水生食物网中积累。最高的汞浓度出现在掠食性鱼类中。濒危的科罗拉多鱒鱼（Ptychocheilus lucius）是一种寿命长、处于顶级食物链的特有鱼类，分布于科罗拉多河流域。通过分析使用非致死技术采集的肌肉组织，评估了科罗拉多鱒鱼和另一种本地鱼类——圆尾雅罗鱼（Gila robusta）暴露在汞下的情况。从该物种目前分布范围内的关键栖息地捕获的、长度超过 400 毫米的科罗拉多鱒鱼的汞浓度超过了组织阈效应水平 0.2 µg/g 湿重（WW）（肌肉中为 0.31 µg/g WW），这一水平推荐用于保护鱼类免受伤害。汞是一种神经毒素和内分泌干扰物，对鱼类的影响可能包括降低躲避捕食者、获取食物和繁殖的能力。在怀特河（绿河的一条支流）采集的科罗拉多鱒鱼和圆尾雅罗鱼的汞浓度最高。来自怀特河和绿河的科罗拉多鱒鱼的汞浓度最高，而相对身体状况最低。暴露在高浓度的汞下可能与其他威胁因素一起，损害科罗拉多鱒鱼的种群生存能力和最终的恢复。
