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Integrating ecosystem metabolism and consumer allochthony reveals nonlinear drivers in lake organic matter processing

August 6, 2021

Lakes process both terrestrial and aquatic organic matter, and the relative contribution from each source is often measured via ecosystem metabolism and terrestrial resource use in the food web (i.e., consumer allochthony). Yet, ecosystem metabolism and consumer allochthony are rarely considered together, despite possible interactions and potential for them to respond to the same lake characteristics. In this study, we compiled global datasets of lake gross primary production (GPP), ecosystem respiration (ER), and zooplankton allochthony to compare the strength and shape of relationships with physicochemical characteristics across a broad set of lakes. GPP was positively related to total phosphorus (TP) in lakes with intermediate TP concentrations (11–75 μg L−1) and was highest in lakes with intermediate dissolved organic carbon (DOC) concentrations. While ER and GPP were strongly positively correlated, decoupling occurred at high DOC concentrations. Lastly, allochthony had a unimodal relationship with TP and related variably to DOC. By integrating metabolism and allochthony, we identified similar change points in GPP and zooplankton allochthony at intermediate DOC (4.5–10 mg L−1) and TP (8–20 μg L−1) concentrations, indicating that allochthony and GPP may be coupled and inversely related. The ratio of DOC:nutrients also helped to identify conditions where lake organic matter processing responded more to autochthonous or allochthonous organic matter sources. As lakes globally face eutrophication and browning, predicting how lake organic matter processing will respond requires an updated paradigm that incorporates nonlinear dynamics and interactions.

Citation Information

Publication Year 2022
Title Integrating ecosystem metabolism and consumer allochthony reveals nonlinear drivers in lake organic matter processing
DOI 10.1002/lno.11907
Authors Meredith A. Holgerson, Rachel A. Hovel, Patrick T. Kelly, Lauren E Bortolotti, Jennifer A. Brentrup, Amber R Bellamy, Samantha K. Oliver, Alexander J Reisenger
Publication Type Article
Publication Subtype Journal Article
Series Title Limnology and Oceanography
Index ID 70224247
Record Source USGS Publications Warehouse
USGS Organization Wisconsin Water Science Center; WMA - Integrated Information Dissemination Division