Response of boreal lakes to changing wind strength: coherent physical changes across two large lakes but varying effects on primary producers over the 20th century

Strock, Kristin E.; Saros, Jasmine E.; McGowan, Suzanne; Edlund, Mark B.; Engstrom, Daniel R.

Abstract

Near‐surface wind speeds have changed over recent decades, raising questions about the extent to which these changes are altering the vertical thermal structure of lakes and affecting lake food webs. Neo‐ and paleolimnological techniques were used to assess wind‐driven changes in lake thermal habitat and resulting effects on primary producers in two lakes in Isle Royale National Park, an island archipelago located in Lake Superior, where wind speed has increased in recent decades. Responses in Siskiwit Lake, a large (16 km2 surface area), deep (Zmax = 49 m), oligotrophic lake, were compared to those of Lake Desor, a moderately large (4.3 km2) but shallower (Zmax = 13 m), mesotrophic lake. High‐frequency sensor data suggested that changes in wind speed affected epilimnion thickness in both lakes synchronously (ρ = 0.7, p [less than] 0.001). Diatom‐inferred mixing depths suggested a coherent shift in both lakes to deeper mixing (an increase of 3 and 6 m) since 1920 (ρ = 0.8), which was correlated with an increase in regional wind speed during the 20th century at the decadal‐scale in Lake Desor and Siskiwit Lake (ρ = 0.6 and 0.4, respectively). In Lake Desor, algal biomass declined as mixing deepened from 1920 to 1980, and then cyanobacteria and cryptophyte pigments increased from 1980 to present, a period of inferred stable and deep mixing. Algal pigment concentrations in Siskiwit Lake were unchanged as mixing depth deepened. Although changes in wind speed altered lake physical structure similarly, the ecological consequences of these changes differed between lakes and were most likely influenced by lake‐specific variability in nutrient and light availability.

Citation

Strock, K. E., Saros, J. E., McGowan, S., Edlund, M. B., & Engstrom, D. R. (2019). Response of boreal lakes to changing wind strength: coherent physical changes across two large lakes but varying effects on primary producers over the 20th century. Limnology and Oceanography, 64(5), 2237-2251. https://doi.org/10.1002/lno.11181

• Journal Article Type: Article
• Acceptance Date: Mar 14, 2019
• Online Publication Date: Apr 25, 2019
• Publication Date: 2019-09
• Deposit Date: Apr 25, 2019
• Publicly Available Date: Apr 26, 2019
• Journal: Limnology and Oceanography
• Print ISSN: 0024-3590
• Electronic ISSN: 1939-5590
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 64
• Issue: 5
• Pages: 2237-2251
• DOI: https://doi.org/10.1002/lno.11181
• Keywords: Aquatic science; Oceanography
• Public URL: https://nottingham-repository.worktribe.com/output/1842476
• Publisher URL: https://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lno.11181