MARE - Marine and Environmental Sciences Centre, ISPA - Instituto Universitário, Rua Jardim do Tabaco, 1149-041 Lisboa, Portugal.
CESAM - Centre for Environmental and Marine Studies, Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.
Sci Total Environ. 2021 Jun 25;775:145796. doi: 10.1016/j.scitotenv.2021.145796. Epub 2021 Feb 12.
Global mercury pollution has markedly and consistently grown over the past 70 years (although with regional variations in trends) and is a source of major concern. Mercury contamination is particularly prevalent in biota of the mesopelagic layers of the open ocean, but these realms are little studied, and we lack a large scale picture of contamination in living organisms of this region. The Bulwer's petrel Bulweria bulwerii, a species of migratory seabird, is a highly specialised predator of mesopelagic fish and squid, and therefore can be used as a bioindicator for the mesopelagic domain. Mercury accumulated by the birds through diet is excreted into feathers during the moulting process in adults and feather growth in chicks, reflecting contamination in the non-breeding and breeding periods, respectively, and hence the influence of different, largely non-overlapping breeding and non-breeding ranges. We studied mercury in feathers and the trophic position in two colonies from the Atlantic Ocean (Portugal and Cape Verde) and two colonies from the Pacific Ocean (Japan and Hawaii). We found significantly lower levels of mercury in adult and chick samples from the Pacific Ocean compared with samples from the Atlantic Ocean. However, we did not detect differences in trophic position of chicks among colonies and oceans, suggesting that differences in mercury measured in feathers reflect levels of environmental contamination, rather than differences in the structure of the trophic chain in different oceans. We conclude that despite a reduction in mercury levels in the Atlantic in recent decades, mesopelagic organisms in this ocean remain more heavily contaminated than in the Pacific at tropical and subtropical latitudes. We suggest that Bulwer's petrel is a highly suitable species to monitor the global contamination of mercury in the mesopelagic domain.
全球汞污染在过去 70 年中显著且持续增长（尽管趋势存在区域性差异），是一个主要关注的问题。汞污染在开阔海洋中层水生物群中尤为普遍，但这些领域研究较少，我们缺乏该区域生物体内污染的大规模情况。Bulwer's 海燕 Bulweria bulwerii 是一种迁徙海鸟，是中层水鱼类和鱿鱼的高度专业化捕食者，因此可以用作中层水域的生物指标。鸟类通过饮食积累的汞在成年鸟类换羽过程中和雏鸟的羽毛生长过程中排泄到羽毛中，分别反映了非繁殖期和繁殖期的污染情况，因此反映了不同、主要不重叠的繁殖和非繁殖范围的影响。我们研究了大西洋（葡萄牙和佛得角）和太平洋（日本和夏威夷）两个繁殖地的羽毛和营养级中的汞。我们发现，与大西洋的样本相比，来自太平洋的成年和雏鸟样本中的汞含量明显较低。然而，我们没有发现不同繁殖地和海洋中雏鸟营养级的差异，这表明羽毛中测量的汞差异反映了环境污染水平，而不是不同海洋中食物链结构的差异。我们的结论是，尽管近年来大西洋的汞水平有所下降，但在热带和亚热带纬度，该海洋的中层水生物仍比太平洋受到更严重的污染。我们认为，Bulwer's 海燕是一种非常适合监测全球中层水域汞污染的物种。
