(Table 2) Concentrations of persistant organic pollutants in the yolk of glaucous gull eggs, Bjørnøya, Svalbard archipelago

It is largely unknown if and how persistent organic pollutants (POPs) affect the transfer of maternal hormones to eggs. This occurs despite an increasing number of studies relating environmental conditions experienced by female birds at the time of egg formation to maternal hormonal effects. Here we report the concentrations of maternal testosterone, 17beta-estradiol and major classes of POPs (organochlorines, brominated flame retardants and metabolically-derived products) in the yolk of unincubated, third-laid eggs of the glaucous gull (Larus hyperboreus), a top-predator in the Arctic marine environment. Controlled for seasonal and local variation, positive correlations were found between the concentrations of certain POPs and testosterone. Contaminant-related changes in the relative concentrations of testosterone and 17beta-estradiol were also observed. In addition, yolk steroid concentrations were associated with contaminant profiles describing the proportions of different POPs present in the yolk. Eggs from nests in which two sibling eggs hatched or failed to hatch differed in POP profiles and in the relative concentrations of testosterone and 17beta-estradiol. Although the results of this correlative study need to be interpreted with caution, they suggest that contaminant-related changes in yolk steroids may occur, possibly affecting offspring performance over and above toxic effects brought about by POPs in eggs.

目前学界对持久性有机污染物（Persistent Organic Pollutants，POPs）是否会以及如何影响母体激素向卵内的传递仍尚不明确。尽管已有越来越多研究将鸟类雌鸟在卵形成阶段所经历的环境条件与母体激素效应相联系，但该问题仍未得到充分解答。本研究测定了北极海洋环境顶级捕食者北极鸥（Larus hyperboreus）未孵化的第三枚卵的卵黄中，母体睾酮（testosterone）、17β-雌二醇（17beta-estradiol）以及主要类别持久性有机污染物（包括有机氯类、溴化阻燃剂及其代谢产物）的浓度。在控制季节与局部环境差异的条件下，研究发现部分持久性有机污染物的浓度与睾酮浓度呈正相关；同时还观察到睾酮与17β-雌二醇的相对浓度随污染物暴露发生改变。此外，卵黄类固醇激素浓度与表征卵内不同持久性有机污染物占比的污染物特征谱存在关联。同一巢中两枚同窝卵的孵化结果（成功孵化或未孵化）存在差异，其卵内持久性有机污染物特征谱以及睾酮与17β-雌二醇的相对浓度亦不相同。尽管本项相关性研究的结果需谨慎解读，但研究结果表明，卵黄类固醇激素可能随污染物暴露发生改变，其影响可能超出卵内持久性有机污染物本身的毒性效应，进而对子代生存表现产生作用。