Warming winters threaten peripheral Arctic charr populations of Europe
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Warming winters threaten peripheral Arctic charr populations of Europe Seán Kelly 1 & Tadhg N. Moore 1 & Elvira de Eyto 2 & Mary Dillane 2 & Chloé Goulon 3 & Jean Guillard 3 & Emilien Lasne 4 & Phil McGinnity 2,5 & Russell Poole 2 & Ian J. Winfield 6 & R. Iestyn Woolway 7 & Eleanor Jennings 1 Received: 1 May 2020 / Accepted: 5 October 2020/ # The Author(s) 2020
Abstract
As the global climate warms, the fate of lacustrine fish is of huge concern, especially given their sensitivity as ectotherms to changes in water temperature. The Arctic charr (Salvelinus alpinus L.) is a salmonid with a Holarctic distribution, with peripheral populations persisting at temperate latitudes, where it is found only in sufficiently cold, deep lakes. Thus, warmer temperatures in these habitats particularly during early life stages could have catastrophic consequences on population dynamics. Here, we combined lake temperature observations, a 1-D hydrodynamic model, and a multi-decadal climate reanalysis to show coherence in warming winter water temperatures in four European charr lakes near the southernmost limit of the species’ distribution. Current maximum and mean winter temperatures are on average ~ 1 °C warmer compared to early the 1980s, and temperatures of 8.5 °C, adverse for high charr egg survival, have frequently been exceeded in recent winters. Simulations of winter lake temperatures toward century-end showed that these warming trends will continue, with further increases of 3–4 °C projected. An additional 324 total accumulated degree-days during winter is projected on average across lakes, which could impair egg quality and viability. We suggest that the perpetuating winter warming trends shown here will imperil the future status of these lakes as charr refugia and generally do not augur well for the fate of coldwater-adapted lake fish in a warming climate. Keywords Arctic charr . Lake ecosystems . Biodiversity conservation . Hydrodynamic modelling . Climate reanalysis . General circulation model . Winter limnology
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10584-02002887-z) contains supplementary material, which is available to authorized users.
* Seán Kelly [email protected] Extended author information available on the last page of the article
Climatic Change
1 Introduction Owing to their intrinsic relationship with the overlying atmosphere and surrounding landscape, lakes are one of the most sensitive habitats to changes in climate. Mounting evidence has revealed that over the past century, freshwater lake temperatures have risen, owing to the secular trend in global climate (Livingstone 2003; O’Reilly et al. 2015; Woolway et al. 2019). Some biogeochemical and biological consequences of warming lake temperatures have already been documented, including oxygen depletion at depth (e.g. Jankowski et al. 2006), decreased carbon sequestration (e.g. Yvon-Durocher et al. 2017), and changing phyto- (e.g. Reavie et al. 2017) and zooplankton (e.g. Carter et al. 2017) populati
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