Piczak Morgan L, Sergio Ava J A, Lennox Robert J, Theysmeyer Tys, Bowman Jennfier E, Midwood Jonathan D, Cooke Steven J
Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada.
Ocean Tracking Network, Dalhousie University, Halifax, Nova Scotia, Canada.
Glob Chang Biol. 2025 Aug;31(8):e70436. doi: 10.1111/gcb.70436.
Freshwater ecosystems around the world are increasingly impacted by climate change, yet there remains a lack of long-term empirical data on how these changes are manifesting. In the Laurentian Great Lakes, a globally significant freshwater system, fish and their habitats are expected to be affected by warming water temperatures and increasing risks of species invasions. Despite these projections, relatively few studies have documented whether such shifts are already occurring. Our objective was to assess how climate change has influenced the community and migration phenology of native and non-native fishes that use coastal wetlands in the Great Lakes. To do so, we analyzed local summer water temperatures and a 27-year dataset (1997-2023) comprising arrivals of 16 fish species intercepted at the Cootes Paradise Marsh Fishway, a common carp (Cyprinus carpio) exclusion barrier at the western end of Lake Ontario. Over the study period, we found that mean summer water temperatures increased by over 1°C, consistent with broader global warming trends. Using non-metric multidimensional scaling, we observed a unidirectional shift in fish community structure over time, rather than cyclical fluctuations or stabilization, indicating sustained ecological change. Analyses on phenology revealed that first, peak, and last arrival dates occurred earlier over time, while the duration of presence at the Fishway decreased for both native and non-native species. These results provide evidence that climate change is already altering the community and phenology of fishes in Great Lakes wetlands. More broadly, our findings contribute to the growing body of literature showing that climate-driven phenological shifts are reshaping freshwater ecosystems globally, underscoring the need for adaptive, climate-informed conservation and management strategies.
世界各地的淡水生态系统正日益受到气候变化的影响，但对于这些变化如何显现，仍缺乏长期的实证数据。在具有全球重要意义的淡水系统—— Laurentian五大湖，鱼类及其栖息地预计将受到水温上升和物种入侵风险增加的影响。尽管有这些预测，但相对较少的研究记录了这种变化是否已经发生。我们的目标是评估气候变化如何影响五大湖沿岸湿地中本地和非本地鱼类的群落和洄游物候。为此，我们分析了当地夏季水温以及一个长达27年的数据集（1997年至2023年），该数据集包含在库茨天堂沼泽鱼道截获的16种鱼类的到达情况，库茨天堂沼泽鱼道是安大略湖西端的一个鲤鱼（Cyprinus carpio）排除屏障。在研究期间，我们发现夏季平均水温上升了超过1°C，这与更广泛的全球变暖趋势一致。使用非度量多维标度法，我们观察到鱼类群落结构随时间发生单向变化，而不是周期性波动或稳定，这表明生态变化持续存在。对物候的分析表明，本地和非本地物种的首次到达、高峰到达和最后到达日期都随时间提前，而在鱼道停留的持续时间缩短。这些结果证明气候变化已经在改变五大湖湿地鱼类的群落和物候。更广泛地说，我们的研究结果有助于丰富越来越多的文献，这些文献表明气候驱动的物候变化正在重塑全球淡水生态系统，强调了制定适应性的、考虑气候因素的保护和管理策略的必要性。
