Hydroclimate variability affects habitat-specific (open water and littoral) lake metabolism (Repository)

Abstract

Lakes integrates the signals of changing hydroclimate in their surrounding basin which reflects as changing in gross primary production (GGP), respiration (R), and net ecosystem production (NEP). Despite the importance of the littoral habitats for lakes and their sensitivity to hydroclimatic variability, most research continues to focus only on the changes produce on the open water habitat. We analyze how years with different hydroclimate, specifically ice-out dates and snow water equivalent (SWE), triggered different metabolism responses in the open water and habitats of a subalpine lake. Compared to the average hydroclimatic year, the dry (early ice-out date and low SWE) and wet (late ice-out date and high SWE) years had lower GPP and R rates in both habitats. Furthermore, consumers biomass decreases during dry and wet years. Also, we observed GPP, and R reduced the most in the littoral habitat. Consequently, the relative contribution to total lake GPP and R of the littoral habitat decreased, and the contribution of the open water habitat increased during the dry and wet years. We demonstrate that extreme hydroclimatic conditions produce a decrease in productivity and consumers, and we also show that within-lake habitats do not have equivalent responses to climate forcing. Our study has implications for how ecosystem scientists and managers quantify the absolute and relative contributions of the littoral habitat to whole lake production in the context of climate variation.