U.S. Geological Survey, Western Ecological Research Center, Davis Field Station, One Shields Avenue, University of California, Davis, California 95616, USA.
Environ Sci Technol. 2009 Nov 15;43(22):8658-64. doi: 10.1021/es901400c.
Small fish are commonly used to assess mercury (Hg) risk to wildlife and monitor Hg in wetlands. However, limited research has evaluated short-term Hg variability in small fish, which can have important implications for monitoring programs and risk assessment. We conducted a time-series study of Hg concentrations in two small fish species representing benthic (longjaw mudsuckers [Gillichthys mirabilis]) and pelagic (threespine sticklebacks [Gasterosteus aculeatus]) food-webs within three wetland habitats in San Francisco Bay Estuary. We simultaneously monitored prey deliveries, nest initiation, and chick hatching dates of breeding Forster's terns (Sterna forsteri), the most abundant nesting piscivore in the region. Mudsuckers and sticklebacks were the predominant prey fish, comprising 36% and 25% of tern diet, and Hg concentrations averaged (geometric mean +/- SE, microg/g dw) 0.44 +/- 0.01 and 0.68 +/- 0.03, respectively. Fish Hg concentrations varied substantially over time following a quadratic form in both species, increasing 40% between March and May then decreasing 40% between May and July. Importantly, Forster's terns initiated 68% of nests and 31% of chicks hatched during the period of peak Hg concentrations in prey fish. These results illustrate the importance of short-term temporal variation in small fish Hg concentrations for both Hg monitoring programs and assessing wildlife risk.
小鱼通常被用于评估野生动物的汞（Hg）风险，并监测湿地中的汞。然而，对于小鱼体内汞的短期变化，相关研究还很有限，而这一变化对于监测项目和风险评估可能具有重要意义。本研究在旧金山湾河口的三个湿地生境中，对两种小鱼（底栖的（长吻泥鱼[Gillichthys mirabilis]）和浮游的（三刺棘鱼[Gasterosteus aculeatus]））的汞浓度进行了时间序列研究，这两种小鱼分别代表了底栖和浮游食物链。我们同时监测了繁殖的美洲红鹈鹕（Sterna forsteri）的捕食者的猎物投放、巢的开始和雏鸟孵化日期。美洲红鹈鹕是该地区最丰富的筑巢捕食者，在其饮食中，泥鱼和棘鱼分别占 36%和 25%，平均汞浓度（几何平均值 +/- SE，微克/克干重）分别为 0.44 +/- 0.01 和 0.68 +/- 0.03。两种鱼类的汞浓度在时间上都呈现出二次形式的显著变化，在 3 月至 5 月之间增加了 40%，然后在 5 月至 7 月之间减少了 40%。重要的是，美洲红鹈鹕在猎物鱼体内汞浓度达到峰值的时期，有 68%的巢和 31%的雏鸟开始孵化。这些结果说明了小鱼体内汞浓度短期变化对汞监测项目和评估野生动物风险的重要性。
