Centre d'Etudes Biologiques de Chizé, CEBC UMR 7372 CNRS-Université de La Rochelle, 79360 Villiers en Bois, France; Réserve Naturelle Nationale de Chérine, Maison de la Nature et de la Réserve, 36290 Saint-Michel-en-Brenne, France.
Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-Université de La Rochelle, 2 rue Olympe de Gouges, 17000 La Rochelle, France.
Sci Total Environ. 2018 Sep 1;635:20-25. doi: 10.1016/j.scitotenv.2018.04.029. Epub 2018 Apr 13.
The effects of Hg contamination are presumably widespread across the components of aquatic ecosystems, but investigations have been mainly focused on freshwater fish, because this biota represents a major source of Hg for human populations. Yet, the possible bioaccumulation of Hg on other freshwater meso- and apex-predators (e.g., amphibians, reptiles) has been largely overlooked, especially in Western Europe. In this study, the determinants of Hg concentrations were assessed for the viperine snake (Natrix maura) across 6 populations (>130 individuals sampled in 2016 and 2017) in France and Spain. Specifically, body size, sex, and diet were compared with Hg concentrations measured in ventral scales. Overall, N. maura accumulated Hg in their scales. Sex did not seem to influence Hg concentrations in this species. Significant differences in Hg concentrations were observed between study sites, and these differences were likely to be mediated by site-specific diet. Frog-eating individuals were characterized not only by lower mean values of Hg (0.194±0.018μg·g versus 0.386±0.032μg·g for piscivorous individuals), but also by weaker slopes of the body size-Hg relationship as compared to fish-eating snakes, suggesting strong differences in accumulation rates due to food resources. Importantly, the highest slope of the body size-Hg relationship and the highest values of Hg were found in individuals foraging on trout raised by a fish farm, suggesting that fish farming may contribute to Hg contamination in inland freshwater systems. Finally, our results are compared with data on Hg concentrations in other species of aquatic snakes, in order to provide a comparative point for future studies.
汞污染的影响可能广泛存在于水生生态系统的各个组成部分中，但调查主要集中在淡水鱼类上，因为这一生物群是人类汞的主要来源。然而，其他淡水中型和顶级捕食者（如两栖动物、爬行动物）中汞的可能生物累积却在很大程度上被忽视了，尤其是在西欧。在这项研究中，评估了 6 个种群（2016 年和 2017 年采集了超过 130 个个体）中蝰蛇（Natrix maura）的汞浓度决定因素。具体来说，比较了腹鳞中的汞浓度与蛇的体型大小、性别和饮食。总的来说，N. maura 在它们的鳞片中积累了汞。性别似乎没有影响到该物种的汞浓度。研究地点之间观察到了汞浓度的显著差异，这些差异可能是由特定地点的饮食差异引起的。以青蛙为食的个体不仅具有较低的汞浓度平均值（0.194±0.018μg·g 比以鱼类为食的个体的 0.386±0.032μg·g），而且体型大小-汞关系的斜率也较弱，这表明由于食物资源的不同，积累率有很大的差异。重要的是，在以养殖场养殖的鳟鱼为食的个体中，体型大小-汞关系的斜率最大，汞浓度最高，这表明鱼类养殖可能导致内陆淡水系统的汞污染。最后，我们将结果与其他水生蛇类的汞浓度数据进行了比较，以便为未来的研究提供一个比较点。
