Elliott Kyle Hamish, Cesh Lillian S, Dooley Jessica A, Letcher Robert J, Elliott John E
Department of Zoology, Z320 Duff Roblin Building, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
Sci Total Environ. 2009 Jun 1;407(12):3867-75. doi: 10.1016/j.scitotenv.2009.02.027. Epub 2009 Apr 1.
Concentrations of persistent contaminants often vary widely among individuals within a population. We hypothesized that such variation was caused mainly by differences in diet (biomagnification) and in coastal systems by the tendency of marine systems to act as contaminant sinks. We examined the relationship between contaminant concentrations and stable isotope ratios in nestling plasma from an apex predator with a particularly broad diet. Our study included freshwater, estuarine, inshore and pelagic breeding sites. Bald eagles (Haliaeetus leucocephalus) at the pelagic marine sites showed high trophic level and marine input, eagles at the freshwater sites showed low trophic level and marine input, and eagles at the estuarine and inshore marine sites had intermediate values. The relationship between trophic level and marine input may reflect longer food chains in pelagic compared to terrestrial ecosystems. summation operator PCBs and DDE concentrations generally increased with trophic level and marine input, with the exception of the freshwater sites, while summation operator PBDEs, hydroxylated-PBDEs and hydroxylated-PCBs increased with marine input, but were independent of trophic level. The relationships for summation operator PCBs and DDE were often slightly stronger with marine input than trophic level, suggesting that oceanographic processes may be more important than trophic level. At freshwater locations, spatial variation may be more important than trophic level due to the heterogeneity of contaminant profiles between feeding locations (lakes, rivers, agricultural fields). Adults had similar isotopic composition to their chicks but higher contamination. Based on nests where prey composition was determined independently, isotopic enrichment values for nestling plasma were 1.6+/-0.1 (delta(15)N) and -0.4+/-0.2 (delta(13)C). We conclude that trophic level and marine influence are significant factors influencing PCB and DDE concentrations in eagles. However, trophic level in particular did not influence PBDEs, possibly due to their being metabolized by eagles.
持久性污染物的浓度在种群内个体之间往往差异很大。我们假设这种差异主要是由饮食差异（生物放大作用）造成的，在沿海系统中则是由于海洋系统作为污染物汇的趋势。我们研究了一种食性特别广泛的顶级捕食者雏鸟血浆中污染物浓度与稳定同位素比率之间的关系。我们的研究包括淡水、河口、近岸和远洋繁殖地。远洋海洋繁殖地的白头海雕（Haliaeetus leucocephalus）表现出高营养级和海洋物质输入，淡水繁殖地的白头海雕表现出低营养级和海洋物质输入，河口和近岸海洋繁殖地的白头海雕则处于中间值。营养级与海洋物质输入之间的关系可能反映出与陆地生态系统相比，远洋生态系统中的食物链更长。多氯联苯和滴滴涕的总浓度一般随营养级和海洋物质输入而增加，但淡水繁殖地除外，而多溴二苯醚、羟基化多溴二苯醚和羟基化多氯联苯随海洋物质输入而增加，但与营养级无关。多氯联苯和滴滴涕总浓度与海洋物质输入的关系通常比与营养级的关系略强，这表明海洋学过程可能比营养级更重要。在淡水区域，由于觅食地点（湖泊、河流、农田）之间污染物分布的异质性，空间变化可能比营养级更重要。成年白头海雕的同位素组成与其雏鸟相似，但污染物含量更高。基于独立确定猎物组成的巢穴，雏鸟血浆的同位素富集值为1.6±0.1（δ15N）和 -0.4±0.2（δ13C）。我们得出结论，营养级和海洋影响是影响白头海雕体内多氯联苯和滴滴涕浓度的重要因素。然而，营养级尤其不影响多溴二苯醚，可能是因为它们会被白头海雕代谢。
