Department of Biology, Western University, London, Ontario, Canada.
Department of Physical and Environmental Sciences, University of Toronto-Scarborough, Toronto, Ontario, Canada.
Glob Chang Biol. 2022 Apr;28(7):2272-2285. doi: 10.1111/gcb.16079. Epub 2022 Jan 19.
Ecologists collectively predict that climate change will enhance phytoplankton biomass in northern lakes. Yet there are unique variations in the structures and regulating functions of lakes to make this prediction challengeable and, perhaps, inaccurate. We used archived Landsat TM/ETM+ satellite products to estimate epilimnetic chlorophyll-a (Chl-a) concentration as a proxy for phytoplankton biomass in 281 northern temperate lakes over 28 years. We explored the influence of climate (air temperature, precipitation) and landscape proxies for nutrient sources (proportion of wetlands in a contributing catchment, size of the littoral zone, potential for wind-driven sediment resuspension as estimated by the dynamic ratio) or nutrient sinks (lake volume) in a random forest model to explain heterogeneity in peak Chl-a. Lakes with higher Chl-a (median Chl-a = 2.4 μg L , n = 40) had smaller volumes (<44 × 10 m ) and were more sensitive to increases in temperature. In contrast, lakes with lower Chl-a (median Chl-a = 0.6 μg L , n = 241) had larger volumes (≥44 × 10 m ), contributing catchments with smaller proportions of wetlands (<4.5% of catchment area, n = 70), smaller littoral zones (<16.4 ha, n = 137), minimal wind-driven sediment resuspension (as defined by the dynamic ratio; <0.45, n = 232), and were more sensitive to increases in precipitation. Lakes with larger volumes were generally less responsive to climate factors; however, larger volume lakes with a significant proportion of wetlands and larger littoral zones behaved similarly to lakes with smaller volumes. Our finding that lakes with different landscape properties respond differently to climate factors may help predict the susceptibility of lakes to eutrophication under changing climatic conditions.
生态学家普遍预测，气候变化将增加北方湖泊的浮游植物生物量。然而，湖泊的结构和调节功能存在独特的变化，使得这一预测具有挑战性，甚至可能不准确。我们使用存档的 Landsat TM/ETM+ 卫星产品来估算 281 个北方温带湖泊在 28 年期间的上混合层叶绿素-a（Chl-a）浓度，以作为浮游植物生物量的代表。我们探索了气候（气温、降水）和景观代理的养分源（集水区内湿地的比例、滨湖区的大小、风驱动沉积物再悬浮的潜力（由动态比估计）或养分汇（湖泊体积）对解释上混合层 Chl-a 峰值的异质性的影响。Chl-a 较高的湖泊（中位数 Chl-a=2.4μg/L，n=40）体积较小（<44×10 3 m），对温度升高更敏感。相比之下，Chl-a 较低的湖泊（中位数 Chl-a=0.6μg/L，n=241）体积较大（≥44×10 3 m），集水区内湿地的比例较小（<4.5%的流域面积，n=70），滨湖区较小（<16.4ha，n=137），风驱动沉积物再悬浮最小（动态比定义为<0.45，n=232），对降水增加更敏感。体积较大的湖泊通常对气候因素的反应较小；然而，具有较大比例湿地和较大滨湖区的较大体积湖泊的行为与较小体积湖泊相似。我们的研究结果表明，具有不同景观特征的湖泊对气候因素的反应不同，这可能有助于预测湖泊在气候变化条件下对富营养化的敏感性。
