Matias Ricardo S, Guímaro Hugo R, Bustamante Paco, Seco José, Chipev Nesho, Fragão Joana, Tavares Sílvia, Ceia Filipe R, Pereira Maria E, Barbosa Andrés, Xavier José C
University of Coimbra, MARE - Marine and Environmental Sciences Centre, Department of Life Sciences, 3000-456, Coimbra, Portugal.
University of Coimbra, MARE - Marine and Environmental Sciences Centre, Department of Life Sciences, 3000-456, Coimbra, Portugal.
Environ Pollut. 2022 Jul 1;304:119199. doi: 10.1016/j.envpol.2022.119199. Epub 2022 Mar 22.
Under the climate change context, warming Southern Ocean waters may allow mercury (Hg) to become more bioavailable to the Antarctic marine food web (i.e., ice-stored Hg release and higher methylation rates by microorganisms), whose biomagnification processes are poorly documented. Biomagnification of Hg in the food web of the Antarctic Peninsula, one of the world's fastest-warming regions, was examined using carbon (δC) and nitrogen (δN) stable isotope ratios for estimating feeding habitat and trophic levels, respectively. The stable isotope signatures and total Hg (T-Hg) concentrations were measured in Antarctic krill Euphausia superba and several Antarctic predator species, including seabirds (gentoo penguins Pygoscelis papua, chinstrap penguins Pygoscelis antarcticus, brown skuas Stercorarius antarcticus, kelp gulls Larus dominicanus, southern giant petrels Macronectes giganteus) and marine mammals (southern elephant seals Mirounga leonina). Significant differences in δC values among species were noted with a great overlap between seabird species and M. leonina. As expected, significant differences in δN values among species were found due to interspecific variations in diet-related to their trophic position within the marine food web. The lowest Hg concentrations were registered in E. superba (0.007 ± 0.008 μg g) and the highest values in M. giganteus (12.090 ± 14.177 μg g). Additionally, a significant positive relationship was found between Hg concentrations and trophic levels (reflected by δN values), biomagnifying nearly 2 times its concentrations at each level. Our results support that trophic interaction is the major pathway for Hg biomagnification in Southern Ocean ecosystems and warn about an increase in the effects of Hg on long-lived (and high trophic level) Antarctic predators under climate change in the future.
在气候变化背景下，南大洋海水升温可能会使汞（Hg）在南极海洋食物网中的生物可利用性增加（即冰中储存的汞释放以及微生物更高的甲基化率），而其生物放大过程的记录却很少。利用碳（δC）和氮（δN）稳定同位素比率分别估算摄食栖息地和营养级，对世界上变暖最快的地区之一南极半岛食物网中的汞生物放大进行了研究。在南极磷虾（Euphausia superba）以及几种南极捕食者物种中测量了稳定同位素特征和总汞（T-Hg）浓度，这些捕食者物种包括海鸟（巴布亚企鹅Pygoscelis papua、南极企鹅Pygoscelis antarcticus、南极贼鸥Stercorarius antarcticus、多米尼加鸥Larus dominicanus、南极巨海燕Macronectes giganteus）和海洋哺乳动物（南象海豹Mirounga leonina）。注意到物种之间的δC值存在显著差异，海鸟物种和南象海豹之间有很大重叠。正如预期的那样，由于与海洋食物网中营养位置相关的饮食种间差异，发现物种之间的δN值存在显著差异。汞浓度最低的是南极磷虾（0.007±0.008μg/g），最高的是南极巨海燕（12.090±14.177μg/g）。此外，发现汞浓度与营养级（由δN值反映）之间存在显著正相关关系，在每个营养级其浓度生物放大近2倍。我们的结果支持营养相互作用是南大洋生态系统中汞生物放大的主要途径，并警示未来气候变化下汞对长寿（和高营养级）南极捕食者影响的增加。
