Hydroclimate variability affects habitat-specific (pelagic and littoral-benthic) metabolism in a eutrophic terminal lake

This study shows that hydroclimate variability affects habitat-specific (pelagic and littoral-benthic) metabolism in a eutrophic terminal lake. Hydroclimate influences lake metabolism (gross primary production, GPP; ecosystem respiration, ER; and net ecosystem production, NEP). While most research on lake metabolism focuses on pelagic habitats, recent work highlights the importance of littoral-benthic zones, which often contribute disproportionately to whole-lake production. Terminal lakes, occurring in closed basins and representing over 40% of global lake volume, are sensitive to hydroclimatic variability because small changes in precipitation or evaporation can substantially alter their hydrological and biogeochemical dynamics. We examined how years with differing snow water equivalent (SWE) influenced metabolic responses in the pelagic and littoral-benthic habitats of Summit Lake, a eutrophic terminal lake in a semiarid montane region with strong interannual climate variability. Using dissolved oxygen sensors and metabolism models across three contrasting years, we found that GPP and ER in littoral-benthic habitats were higher and more sensitive to hydrological variation than in pelagic waters. Metabolism also varied among littoral sites, with some displaying autotrophy and others heterotrophy. Wet years favored heterotrophic metabolism, whereas dry years favored autotrophic metabolism. Terminal-lake assessments should incorporate spatial heterogeneity and hydroclimatic context, as habitats respond differently to climatic forcing.Unstructured abstract Hydroclimate variability drives metabolic differences in eutrophic terminal lake habitats. Littoral-benthic zones respond more strongly than pelagic areas across dry and wet years, shifting between autotrophy and heterotrophy