Fine-Scale Ecological and Genetic Population Structure of Two Whitefish (Coregoninae) Species in the Vicinity of Industrial Thermal Emissions

Thermal pollution from industrial processes can have negative impacts on the spawning and development of cold-water fish. Point sources of thermal effluent may need to be managed to avoid affecting discrete populations. Correspondingly, we examined fine-scale ecological and genetic population structure of two whitefish species (Coregonus clupeaformis and Prosopium cylindraceum) on Lake Huron, Canada, in the immediate vicinity of thermal effluent from nuclear power generation. Niche metrics using δ13C and δ15N stable isotopes showed high levels of overlap (48.6 to 94.5%) in resource use by adult fish captured in areas affected by thermal effluent compared to nearby reference locations. Isotopic niche size, a metric of resource use diversity, was 1.3- to 2.8-fold higher than reference values in some thermally affected areas, indicative of fish mixing. Microsatellite analyses of genetic population structure (Fst, STRUCTURE and DAPC) indicated that fish captured at all locations in the vicinity of the power plant were part of a larger population extending beyond the study area. In concert, ecological and genetic markers do not support the presence of an evolutionarily significant unit in the vicinity of the power plant. Thus, future research should focus on the potential impacts of thermal emissions on development and recruitment.工业生产过程产生的热污染，会对冷水性鱼类的产卵与发育过程造成负面影响。针对热排放点源需开展管控，以避免其对离散鱼类种群产生不良影响。对此，我们针对加拿大休伦湖紧邻核电热排放区域的采样位点，对两种白鲑——湖白鲑（Coregonus clupeaformis）与圆腹白鱼（Prosopium cylindraceum）的精细尺度生态与遗传种群结构展开了调查。利用δ¹³C与δ¹⁵N稳定同位素计算的生态位指标显示，相较于邻近对照区域，热排放影响区域内捕获的成鱼其资源利用生态位重叠度极高（48.6%至94.5%）。作为资源利用多样性的衡量指标，部分热影响区域内的同位素生态位面积较对照值高出1.3至2.8倍，这表明区域内存在鱼类种群混合现象。针对遗传种群结构的微卫星分析（涵盖Fst固定指数、STRUCTURE与DAPC分析方法）结果显示，发电厂周边所有采样位点捕获的白鲑，均属于研究区域外更大种群的组成部分。综合来看，生态与遗传标记均不支持发电厂周边区域存在进化显著单元（evolutionarily significant unit）的结论。因此，未来研究应聚焦于热排放对鱼类发育与种群补充的潜在影响。