Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, ON, K1A 0H3, Canada.
Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, ON, K1A 0H3, Canada.
Environ Pollut. 2021 Jan 1;268(Pt B):115820. doi: 10.1016/j.envpol.2020.115820. Epub 2020 Oct 13.
Diet, age, and growth rate influences on fish mercury concentrations were investigated for Arctic char (Salvelinus alpinus) and brook trout (Salvelinus fontinalis) in lakes of the eastern Canadian Arctic. We hypothesized that faster-growing fish have lower mercury concentrations because of growth dilution, a process whereby more efficient growth dilutes a fish's mercury burden. Using datasets of 57 brook trout and 133 Arctic char, linear regression modelling showed fish age and diet indices were the dominant explanatory variables of muscle mercury concentrations for both species. Faster-growing fish (based on length-at-age) fed at a higher trophic position, and as a result, their mercury concentrations were not lower than slower-growing fish. Muscle RNA/DNA ratios were used as a physiological indicator of short-term growth rate (days to weeks). Slower growth of Arctic char, inferred from RNA/DNA ratios, was found in winter versus summer and in polar desert versus tundra lakes, but RNA/DNA ratio was (at best) a weak predictor of fish mercury concentration. Net effects of diet and age on mercury concentration were greater than any potential offset by biomass dilution in faster-growing fish. In these resource-poor Arctic lakes, faster growth was associated with feeding at a higher trophic position, likely due to greater caloric (and mercury) intake, rather than growth efficiency.
我们研究了加拿大东部北极地区湖泊中的鱼类饮食、年龄和生长率对鱼类汞浓度的影响，这些鱼类包括北极茴鱼（Salvelinus alpinus）和溪红点鲑（Salvelinus fontinalis）。我们假设，由于生长稀释，生长速度较快的鱼类体内的汞浓度较低，生长稀释过程中，鱼类的汞负荷被更有效地稀释。在 57 条溪红点鲑和 133 条北极茴鱼的数据集上，线性回归模型表明，对于这两个物种，鱼类年龄和饮食指数是肌肉汞浓度的主要解释变量。（基于年龄的长度）生长较快的鱼类处于较高的营养级，因此其汞浓度并不低于生长较慢的鱼类。肌肉 RNA/DNA 比值可作为短期生长率（几天到几周）的生理指标。与夏季相比，冬季北极茴鱼的生长速度较慢，与苔原湖相比，荒漠湖的生长速度较慢，但 RNA/DNA 比值（最多）是鱼类汞浓度的一个较弱预测指标。饮食和年龄对汞浓度的综合影响大于生长较快的鱼类通过生物量稀释带来的任何潜在抵消。在这些资源匮乏的北极湖泊中，较快的生长与处于较高的营养级有关，这可能是由于较高的热量（和汞）摄入，而不是生长效率。
