Lake metabolism provides fundamental information on how C and energy cycle within these systems, and lakes interact with surrounding environments. Assessments of lake gross primary production (GPP) and respiration (R) and their net balance (NEP and P/R) have been limited to communities or to a limited number of lakes and narrow environmental and geographic gradients, because conventional approaches require either long incubations, intensive sampling or deployment of monitoring equipment, none of which are amenable to implementation in large scale studies. Here, we present the preliminary results of a large-scale comparative study of lake metabolism, where we explore the patterns and drivers of GPP, R, NEP and P/R of lakes across Canada, part of the Canadian LakePulse Network. We measured summer mixed-layer metabolic rates in these lakes using an oxygen isotopic (δ¹⁸O₂) approach that combines ambient O₂ concentration and isotopic signature, which provides an integrative snapshot of mixed-layer metabolism in the case of stratified lakes in summer or whole lake metabolism in the case of shallow lakes. The sampled lakes were distributed across major Canadian ecoregions, covering a wide range of in-lake, watershed, and climatic features. GPP and R varied across lakes and regions, as a function of trophic status, dissolved organic carbon (DOC), and chlorophyll a. Preliminary results suggest that there are systematic regional differences in lake metabolism, likely driven by a combination of region-specific landscape properties as well as average regional lakes specific properties.

Primary Presenter: Amir Reza Shahabinia, Université du Québec à Montréal (amir.shahabi66@gmail.com)

Authors:

Amir Reza Shahabinia, Université du Québec à Montréal  (amir.shahabi66@gmail.com)

Matthew Bogard, University of Lethbridge  (matthew.bogard@uleth.ca)

Paul del Giorgio, Université du Québec à Montréal  (del_giorgio.paul@uqam.ca)