The life aquatic in high relief: shifts in the physical and biological characteristics of alpine lakes along an elevation gradient in the Rocky Mountains, USA
Loria K.A., McKnight D., Ragar D.M., Johnson P.T.J. (2020) The Life Aquatic in High Relief: How elevation dictates the physical and biological characteristics of alpine lakes in the Rocky Mountains, USA. Aquatic Sciences 82(1):11. https://doi.org/10.1007/s00027-019-0684-6.
Photo of Blue Lake in August of 2016 by Kelly Loria.
Abstract
Rapidly occurring environmental changes in alpine lakes highlight the importance of better understanding the ecological structure and function associated with these systems. Previous research has identified how the physical characteristics of lakes change as a function of landscape position, but comparatively little is known about shifts in the biotic community across mountain regions. In 2016, we sampled 19 lakes across an elevation gradient (2480–3550 m a.s.l.) within the Rocky Mountains, USA, to evaluate how both the abiotic characteristics of lakes and their planktonic biological communities covaried with elevation. Based on generalized linear mixed models (GLMMs), increases in elevation were associated with decreases in most nutrient concentrations (with the exception of nitrate), dissolved organic carbon, water temperature and lake stratification. Conversely, elevation increases were positively related to nitrate concentrations and water clarity. Extending this analysis to the biological community, we found that higher-elevation lakes exhibited lower phytoplankton and zooplankton densities, whereas elevation associated positively with average zooplankton size. Our data are consistent with the hypothesis that the alpine environment acts as a strong niche filter, limiting the quantity and diversity of taxa to groups capable of tolerating the short growing season, high flushing rate, strong variation in inter annual precipitation, intense ultraviolet radiation exposure, and lower resource availability associated with such habitats.