Belle Simon, Drakare Stina, Richard K Johnson
Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
J Environ Manage. 2025 Jan;373:123546. doi: 10.1016/j.jenvman.2024.123546. Epub 2024 Dec 14.
In the 1980s, liming became a large-scale, governmentally supported restoration program implemented by many countries to mitigate the effects of acidification of freshwaters. Despite some 50 years of liming of thousands of lakes and streams, its efficacy remains largely debated. This study is the first of its kind to use paleolimnological reconstructions using both subfossil chironomid assemblages and their carbon stable isotopic composition to compare the ecological trajectories of limed and control (unlimed) lakes over the last 100 years in order to unravel the effects of liming on Scandinavian lakes. Our study revealed strong effects of liming on lake water chemistry and sedimentary characteristics of limed lakes. Overall, higher present-day pH values were observed in lake water of the limed lakes (average pH of 6.7 ± 0.2) than in control lakes (average pH of 5.9 ± 0.5), and the pH variability was much lower among limed lakes. A decrease in the dissimilarity of the chironomid assemblages among limed lakes was also observed as liming progressed, and the degree of dissimilarity after liming was largely lower than pre-acidified levels. This pattern suggests that liming favoured the selection of similar chironomid taxa in limed lakes, thus providing complementary empirical evidences about the effects of liming on aquatic communities through taxonomic homogenization of chironomid assemblages. As the ecological trajectories of limed and control lakes strongly differed, our study also questions the impact of liming on the resilience of Scandinavian lakes and, importantly, their ability to cope with ongoing and future climatic and environmental changes. Finally, isotope-based results indicated that liming masks potential complex effects on carbon flows at the base of the food web by shifting algal carbon isotopic baselines. The use of carbon stable isotope analysis of chironomid head capsules to study the effects of liming on energy flows within lake food webs is, therefore, not suitable.
20世纪80年代，石灰处理成为许多国家实施的一项大规模、由政府支持的恢复计划，以减轻淡水酸化的影响。尽管对数千个湖泊和溪流进行了约50年的石灰处理，但其效果仍存在很大争议。本研究首次利用古湖沼学重建方法，通过亚化石摇蚊组合及其碳稳定同位素组成，比较了过去100年中施石灰湖泊和对照（未施石灰）湖泊的生态轨迹，以揭示石灰处理对斯堪的纳维亚湖泊的影响。我们的研究揭示了石灰处理对施石灰湖泊的湖水化学和沉积特征有强烈影响。总体而言，施石灰湖泊的湖水现今pH值（平均pH为6.7±0.2）高于对照湖泊（平均pH为5.9±0.5），且施石灰湖泊之间的pH变异性要低得多。随着石灰处理的进行，还观察到施石灰湖泊中摇蚊组合的差异减小，石灰处理后的差异程度大大低于酸化前的水平。这种模式表明，石灰处理有利于在施石灰湖泊中选择相似的摇蚊类群，从而通过摇蚊组合的分类同质化提供了关于石灰处理对水生群落影响的补充实证证据。由于施石灰湖泊和对照湖泊的生态轨迹差异很大，我们的研究还质疑了石灰处理对斯堪的纳维亚湖泊恢复力的影响，重要的是，质疑了它们应对当前和未来气候及环境变化的能力。最后，基于同位素的结果表明，石灰处理通过改变藻类碳同位素基线掩盖了对食物网底部碳流的潜在复杂影响。因此，利用摇蚊头壳的碳稳定同位素分析来研究石灰处理对湖泊食物网内能量流动的影响并不合适。
