Abrupt changes in the physical and biological structure of endorheic upland lakes due to 8-m lake-level variation during the 20 th century

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dc.contributor.authorBjorndahl, Judith A.
dc.contributor.authorGushulak, Cale A.C.
dc.contributor.authorMezzini, Stefano
dc.contributor.authorSimpson, Gavin L.
dc.contributor.authorHaig, Heather A.
dc.contributor.authorLeavitt, Peter R
dc.contributor.authorFinlay, Kerri
dc.date.accessioned2023-04-26T16:51:19Z
dc.date.available2023-04-26T16:51:19Z
dc.date.issued2022-03-07
dc.description© 2022 The Authors. Limnology and Oceanography published by Wiley Periodicals LLC on behalf of Association for the Sciences of Limnology and Oceanography. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.en_US
dc.description.abstractClimate-induced variation in lake level can affect physicochemical properties of endorheic lakes, but its consequences for phototrophic production and regime shifts are not well understood. Here, we quantified changes in the abundance and community composition of phototrophs in Kenosee and White Bear lakes, two endorheic basins in the parkland Moose Mountain uplands of southeastern Saskatchewan, Canada, which have experienced > 8 m declines in water level since ~ 1900. We hypothesized that lower water levels and warmer temperatures should manifest as increased abundance of phytoplankton, particularly cyanobacteria, and possibly trigger a regime shift to turbid conditions due to evaporative concentration of nutrients and solutes. High-resolution analysis of sedimentary pigments revealed an increase in total phototrophic abundance (as β-carotene) concurrent with lake-level decline beginning ~ 1930, but demonstrated little directional change in cyanobacteria. Instead, significant increases in obligately anaerobic purple sulfur bacteria (as okenone) occurred in both lakes during ~ 1930–1950, coeval with alterations to light environments and declines in lake level. The presence of okenone suggests that climate-induced increases in solute concentrations may have favored the formation of novel bacterial habitats where photic and anoxic zones overlapped. Generalized additive models showed that establishment of this unique habitat was likely preceded by increased temporal variance of sulfur bacteria, but not phytoplankton or cyanobacteria, suggesting that this abrupt change to physical lake structure was unique to deep-water environments. Such climate-induced shifts may become more frequent in the region due to hydrological stress on lake levels due to warming temperatures across the Northern Great Plains.en_US
dc.description.authorstatusFacultyen_US
dc.description.peerreviewyesen_US
dc.description.sponsorshipFunding for this project was provided through NSERC Discovery grants to G.L.S., P.R.L., and K.F., the Saskatchewan Ministry of Parks, Culture, and Sport to K.F., the Canada Foundation for Innovation, the Canada Research Chair program, the Province of Saskatchewan, and University of Regina.en_US
dc.identifier.citationBjoerndahl, J.A., C.A.C. Gushulak, S. Mezzini, G.L. Simpson,, H.A. Haig, P.R. Leavitt, and K. Finlay. 2022. Abrupt changes in the physical and biological structure of endorheic upland lakes due to 8-m lake-level variation during the 20th century. Limnol. Oceanogr. 67: 1022-1039. doi.org/10.1002/lnoo.12054.en_US
dc.identifier.doidoi.org/10.1002/lnoo.12054.
dc.identifier.urihttps://hdl.handle.net/10294/15877
dc.language.isoenen_US
dc.publisherWileyen_US
dc.rightsAttribution-NonCommercial 4.0 International*
dc.rights.urihttps://creativecommons.org/licenses/by-nc/4.0/*
dc.titleAbrupt changes in the physical and biological structure of endorheic upland lakes due to 8-m lake-level variation during the 20 th centuryen_US
dc.typeArticleen_US
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