Eagles-Smith Collin A, Ackerman Joshua T, De La Cruz Susan E W, Takekawa John Y
U.S. Geological Survey, Western Ecological Research Center, Davis Field Station, One Shields Avenue, University of California, Davis, CA 95616, USA.
Environ Pollut. 2009 Jul;157(7):1993-2002. doi: 10.1016/j.envpol.2009.03.030. Epub 2009 Apr 23.
We evaluated mercury (Hg) in five waterbird species representing three foraging guilds in San Francisco Bay, CA. Fish-eating birds (Forster's and Caspian terns) had the highest Hg concentrations in their tissues, but concentrations in an invertebrate-foraging shorebird (black-necked stilt) were also elevated. Foraging habitat was important for Hg exposure as illustrated by within-guild differences, where species more associated with marshes and salt ponds had higher concentrations than those more associated with open-bay and tidal mudflats. Importantly, Hg concentrations increased with time spent in the estuary. Surf scoter concentrations tripled over six months, whereas Forster's terns showed an up to 5-fold increase between estuary arrival and breeding. Breeding waterbirds were at elevated risk of Hg-induced reproductive impairment, particularly Forster's terns, in which 48% of breeding birds were at high risk due to their Hg levels. Our results highlight the importance of habitat and exposure timing, in addition to trophic position, on waterbird Hg bioaccumulation and risk.
我们评估了加利福尼亚州旧金山湾代表三个觅食类群的五种水鸟体内的汞（Hg）含量。以鱼类为食的鸟类（弗氏燕鸥和里海燕鸥）组织中的汞浓度最高，但以无脊椎动物为食的滨鸟（黑颈长脚鹬）体内的汞浓度也有所升高。觅食栖息地对汞暴露很重要，这一点在类群内部差异中得到体现，与沼泽和盐池联系更紧密的物种比与开阔海湾和潮间带泥滩联系更紧密的物种汞浓度更高。重要的是，汞浓度随着在河口停留的时间增加而升高。在六个月的时间里，斑脸海番鸭体内的汞浓度增加了两倍，而弗氏燕鸥在到达河口和繁殖之间汞浓度增加了高达5倍。繁殖期水鸟面临汞导致生殖损伤的风险增加，尤其是弗氏燕鸥，其中48%的繁殖期鸟类由于汞含量而处于高风险状态。我们的研究结果突出了栖息地、暴露时间以及营养级对水鸟汞生物累积和风险的重要性。
