CRETUS Institute, Department of Functional Biology, Ecology Unit, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
CRETUS Institute, Department of Functional Biology, Ecology Unit, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Water Res. 2023 May 1;234:119793. doi: 10.1016/j.watres.2023.119793. Epub 2023 Feb 23.
Mercury contamination is a global environmental problem. This pollutant is highly toxic and persistent which makes it extremely susceptible to biomagnify, i.e. increase its concentrations as it moves up the food chain, reaching levels that threaten wildlife and, ultimately, ecosystems' function and structure. Mercury monitoring is thus crucial to determine its potential to damage the environment. In this study, we assessed the temporal trends of the concentrations of Hg in two coastal animal species closely connected by a predator-prey interaction, and evaluated its potential transfer between trophic levels using the δN signatures of the two species. For this, we performed a multi-year survey of the concentrations of total Hg and the values of δN in the mussel Mytilus galloprovincialis (prey) and the dogwhelk Nucella lapillus (predator) sampled along ∼1500 km of the North Atlantic coast of Spain over a 30-year period (five surveys between 1990 and 2021). Concentrations of Hg decreased significantly between the first and the last survey in the two species studied. Except for the 1990 survey, the concentrations of Hg in mussels were amongst the lowest registered in the literature for the North East Atlantic Ocean (NEAO) and the Mediterranean Sea (MS) between 1985 and 2020. Nonetheless, we detected Hg biomagnification in almost all surveys. Worryingly, trophic magnification factors obtained here for total Hg were high and comparable to the found in the literature for methylmercury, the most toxic and readily biomagnified form of this element. The δN values were useful to detect Hg biomagnification under normal circumstances. However, we found that nitrogen pollution of coastal waters differentially affected the δN signatures of mussels and dogwhelks limiting the use of this parameter for this purpose. We conclude that Hg biomagnification could constitute an important environmental hazard even when found at very low concentrations in the lower trophic levels. Also, we warn that use of δN in biomagnification studies when there is some underlying nitrogen pollution problem might lead to misleading conclusions.
汞污染是一个全球性的环境问题。这种污染物具有高度的毒性和持久性，极易在生物体内积累放大，即在食物链中浓度不断增加，达到威胁野生动物、最终影响生态系统功能和结构的水平。因此，汞监测对于确定其对环境的潜在危害至关重要。在这项研究中，我们评估了两种沿海动物物种中汞浓度的时间趋势，这两种物种通过捕食者-猎物相互作用紧密相连，并利用两种物种的 δN 特征评估了它们之间在营养水平上的潜在转移。为此，我们对 1990 年至 2021 年期间在西班牙北大西洋海岸约 1500 公里的范围内采集的贻贝 Mytilus galloprovincialis（猎物）和石鳖 Nucella lapillus（捕食者）中的总汞浓度和 δN 值进行了多年调查（共进行了五次调查）。在研究的两种物种中，Hg 浓度在第一和最后一次调查之间均显著降低。除了 1990 年的调查，在 1985 年至 2020 年期间，贻贝中 Hg 的浓度在东北大西洋（NEAO）和地中海（MS）的文献记录中属于最低水平之列。尽管如此，我们几乎在所有调查中都检测到了 Hg 的生物放大。令人担忧的是，我们在这里获得的总 Hg 营养级放大因子很高，与文献中发现的甲基汞相当，甲基汞是该元素最具毒性和最易生物放大的形式。δN 值可用于在正常情况下检测 Hg 的生物放大。然而，我们发现，沿海水域的氮污染会对贻贝和石鳖的 δN 特征产生不同的影响，从而限制了该参数在这方面的应用。我们的结论是，即使在较低的营养水平上发现非常低浓度的 Hg，它也可能构成一个重要的环境危害。此外，我们警告说，当存在一些潜在的氮污染问题时，在生物放大研究中使用 δN 可能会导致误导性的结论。
