Water column gradients beneath the summer ice of a High Arctic freshwater lake as indicators of sensitivity to climate change

Abstract Ice cover persists throughout summer over many lakes at extreme polar latitudes but is likely to become increasingly rare with ongoing climate change. Here we addressed the question of how summer ice-cover affects the underlying water column of Ward Hunt Lake, a freshwater lake in the Canad...

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Bibliographic Details
Published in:Scientific Reports
Main Authors: Bégin, Paschale N., Tanabe, Yukiko, Rautio, Milla, Wauthy, Maxime, Laurion, Isabelle, Uchida, Masaki, Culley, Alexander I., Vincent, Warwick F.
Other Authors: Fonds de recherche du Québec – Nature et technologies, Northern Scientific Training Program, Centre d'études nordiques, Sentinel North, ArcticNet, Natural Sciences and Engineering Research Council of Canada, Ministry of Education, Culture, Sports, Science
Format: Article in Journal/Newspaper
Language:English
Published: Springer Science and Business Media LLC 2021
Subjects:
Multidisciplinary
Arctic
Climate change
Online Access:http://dx.doi.org/10.1038/s41598-021-82234-z
http://www.nature.com/articles/s41598-021-82234-z.pdf
http://www.nature.com/articles/s41598-021-82234-z
Description
Summary:Abstract Ice cover persists throughout summer over many lakes at extreme polar latitudes but is likely to become increasingly rare with ongoing climate change. Here we addressed the question of how summer ice-cover affects the underlying water column of Ward Hunt Lake, a freshwater lake in the Canadian High Arctic, with attention to its vertical gradients in limnological properties that would be disrupted by ice loss. Profiling in the deepest part of the lake under thick mid-summer ice revealed a high degree of vertical structure, with gradients in temperature, conductivity and dissolved gases. Dissolved oxygen, nitrous oxide, carbon dioxide and methane rose with depth to concentrations well above air-equilibrium, with oxygen values at > 150% saturation in a mid-water column layer of potential convective mixing. Fatty acid signatures of the seston also varied with depth. Benthic microbial mats were the dominant phototrophs, growing under a dim green light regime controlled by the ice cover, water itself and weakly colored dissolved organic matter that was mostly autochthonous in origin. In this and other polar lakes, future loss of mid-summer ice will completely change many water column properties and benthic light conditions, resulting in a markedly different ecosystem regime.

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