WILDFIRE SMOKE AFFECTS LAKE AND POND THERMAL AND METABOLIC REGIMES: A WATERSHED-SCALE INVESTIGATION

Climate change is increasing the likelihood of extreme fires globally. These wildfires produce large smoke plumes that can decrease solar radiation and deposit ash particles across ecosystems. Several key physical, chemical, and biological processes in aquatic ecosystems are controlled by factors affected by smoke. However, the effects of smoke on lake and pond ecosystems are still not well known. We studied effects of wildfire smoke on 2 lakes and 4 ponds in a representative high-elevation (2800-3230 m) watershed in the Sierra Nevada mountains of California. Smoke from major wildfires in 2020 and 2021 covered our study watershed for an average of 49 days between August and October. Using a network of high frequency measurements of water temperature and dissolved oxygen, we found that although lakes and ponds responded synchronously to smoke, the magnitude of effects varied. In general, thermal responses were clearest. Smoke reduced water temperature, with the magnitude of response controlled in part by waterbody size. Changes in rates of primary production associated with smoke were more varied, but also tended to scale with waterbody size. These results suggest that the impacts of smoke on small lakes and ponds are mediated by multiple factors, but that smaller waterbodies may be particularly vulnerable to the effects of smoke. Understanding the factors that mediate lake and pond sensitivity to smoke is a priority given current and projected wildfire regimes in a climate-modified world.

Primary Presenter: Mary Farruggia, University of California Davis (maryjadefarruggia@gmail.com)

Authors:

Mary Farruggia, University of California Davis  (mjfarruggia@ucdavis.edu)

Adrianne Smits, University of California Davis  (asmits@ucdavis.edu)

Steven Sadro, University of California Davis  (ssadro@ucdavis.edu)