Department of Biological Sciences, Dartmouth College, Hanover, NH, USA.
Department of Biological Sciences, Dartmouth College, Hanover, NH, USA.
Ecotoxicol Environ Saf. 2019 Oct 30;182:109440. doi: 10.1016/j.ecoenv.2019.109440. Epub 2019 Jul 20.
Mercury, and particularly its organic form, methylmercury (MeHg), is a ubiquitous environmental contaminant with documented dosage-dependent adverse effects on endpoints spanning many levels of biological organization. However, relatively little is known about the sublethal impacts of environmentally-relevant exposures on behavioral characteristics that may impact predator-prey relationships, and thus the potential for Hg bioaccumulation within food webs due to behavioral impairments. This study investigated the potential for dietary mercury exposure to impair two behavioral outcomes in the highly invasive rusty crayfish, Faxonius rusticus, which are expected to influence interactions with their fish predators: the tail-flip escape response and chelae pinch strength. Field-caught animals were randomly assigned to four dietary treatments with mean (±1 SE) dry-weight total Hg (THg) concentrations of 3.52 ± 0.57, 114.01 ± 4.05, 274.10 ± 0.38, and 565.79 ± 1.33 ng/g in the control, low, moderate and high exposure treatments, respectively, for 16 weeks. After initial observations, exposures began and mass and behavior were measured every two weeks. At the end of the experiment, THg concentrations in tail muscle tissue were significantly higher in the high exposure treatment than in the control and low exposure treatments (Tukey's HSD, family-wise α = 0.05). Exposure-dependent declines in survival, mass, pinch strength, or tail-flip escape response velocity were not detected within the 12- to 16-week experimental exposure period, which represents one season of the crayfish's 3-4 year lifespan. This suggests that crayfish may be relatively tolerant of dietary exposure to sublethal concentrations of mercury within a single season. Further investigation of the physiological underpinnings of this tolerance is warranted.
汞，特别是其有机形式，甲基汞（MeHg），是一种普遍存在的环境污染物，其对生物组织多个层次的终点有剂量依赖性的不良影响已被记录在案。然而，对于环境相关暴露对可能影响捕食者-猎物关系的行为特征的亚致死影响，以及由于行为障碍导致汞在食物网中生物积累的潜在影响，人们知之甚少。本研究调查了饮食中汞暴露对入侵性很强的铁锈螯虾（Faxonius rusticus）两种行为结果的潜在影响，这两种行为结果可能会影响它们与鱼类捕食者的相互作用：尾扇逃避反应和螯肢夹力。从野外捕获的动物被随机分配到四个饮食处理组，每个处理组的干重总汞（THg）浓度分别为 3.52±0.57、114.01±4.05、274.10±0.38 和 565.79±1.33ng/g，分别为对照组、低暴露组、中暴露组和高暴露组，暴露时间为 16 周。在最初的观察之后，开始暴露，每两周测量一次体重和行为。在实验结束时，高暴露组的尾肌组织中的 THg 浓度明显高于对照组和低暴露组（Tukey 的 HSD，组间 α=0.05）。在 12 至 16 周的实验暴露期间，未检测到暴露依赖性的存活率、体重、夹力或尾扇逃避反应速度下降，这代表了螯虾 3 到 4 年寿命中的一个季节。这表明，螯虾在一个季节内可能对饮食中接触亚致死浓度的汞相对耐受。有必要进一步研究这种耐受性的生理基础。
