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Water column changes under ice during different winters in a mid-latitude Mediterranean high mountain lake
Aquatic Sciences ( IF 2.4 ) Pub Date : 2020-02-24 , DOI: 10.1007/s00027-020-0699-z
Ignacio Granados , Manuel Toro , Santiago Giralt , Antonio Camacho , Carlos Montes

Winter limnology has been developed mainly in northern-temperate or subarctic lakes, while mid-latitude Mediterranean high mountain lakes have been less studied during the ice-covered season. We present a five-year study in one of these lower latitude high mountain lakes, conducted with multiprobes located at two different depths recording high-frequency data. We have studied highly contrasted winters regarding temperature and snowfall. The results of a principal component analysis and a subsequent hierarchical clustering show that bottom oxygen depletion under ice is strongly influenced by winter cover thickness and transparency. A thick and opaque winter cover (dark mode) leads to an intense oxygen depletion until anoxia, while a thin and clear winter cover (clear mode) allows higher dissolved oxygen saturation due to oxygen production by photosynthesis. Under unusual conditions of cold and dry climate, only a weak decrease in bottom dissolved oxygen was observed. The extent of dissolved oxygen depletion and its relationship with meteorological parameters and climate patterns are further investigated with generalized additive models. Winter cover thickness and phenology are driven by the joint effect of the North Atlantic Oscillation and East Atlantic climatic patterns. Ice phenology could also influence the following ice-free period given the correlation of lake heat content with the ice-off date and the ice cover length. We propose some features jointly occurring in Lake Cimera as a model for mid-latitude Mediterranean high mountain lakes, including (yet not exclusive) the occurrence of very thick winter covers, the prevalence of dark mode, the relatively high and similar through the years oxygen depletion rates, and high water temperatures during the ice-free periods. It is unclear how the ongoing climate change will affect the prevalence of dark over clear modes due to the expected antagonistic effects of warmer temperatures and lower snowfalls.

中文翻译:

中纬度地中海高山湖泊不同冬季冰下水柱变化

冬季湖沼学主要在北温带或亚北极湖泊中发展,而在冰封季节对中纬度地中海高山湖泊的研究较少。我们在这些低纬度高山湖泊之一中进行了一项为期五年的研究,该研究使用位于两个不同深度的多探头记录高频数据。我们研究了关于温度和降雪的高度对比的冬天。主成分分析和随后的分层聚类结果表明,冰下底部氧气消耗受冬季覆盖厚度和透明度的强烈影响。厚而不透明的冬季覆盖物(黑暗模式)会导致严重的氧气消耗,直到缺氧,而薄而透明的冬季覆盖物(透明模式)由于光合作用产生氧气而允许更高的溶解氧饱和度。在寒冷干燥气候的异常条件下,仅观察到底部溶解氧的微弱减少。溶解氧消耗的程度及其与气象参数和气候模式的关系用广义加法模型进一步研究。冬季覆盖厚度和物候受北大西洋涛动和东大西洋气候模式的共同影响。鉴于湖泊热含量与冰期和冰盖长度的相关性,冰物候也可能影响接下来的无冰期。我们提出了一些共同出现在西梅拉湖的特征,作为中纬度地中海高山湖泊的模型,包括(但不排除)非常厚的冬季覆盖物的出现、黑暗模式的流行、多年来相对较高和相似的氧气消耗率以及无冰期的高水温。由于温度升高和降雪量减少的预期拮抗效应,目前尚不清楚持续的气候变化将如何影响黑暗模式的流行。
更新日期:2020-02-24
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