Anoximixis: Mixing of anoxic bottom waters influences biogeochemical and ecological processes in lakes

Climate change is reshaping lake ecosystems globally, notably through alterations to thermal stratification and mixing regimes. This synthesis describes "anoximixis," the complete mixing of a stratified waterbody with anoxic bottom waters, and reviews the biogeochemical and ecological implications of anoximixis outside of seasonal turnover events. We posit that climate-driven changes to temperature, wind patterns, and storm events may lead to increased frequency of anoximixis in freshwater ecosystems, which could in turn alter biogeochemical cycling, flux, and sequestration of nutrients, contaminants, and C. Anoximixis may also reorganize lake trophic structure, favoring fast-growing phytoplankton species and cyanobacteria, which will alter energy and C transfer to higher trophic levels. Current lake management strategies do not fully address anoximixis-driven water quality degradation, and some may even unintentionally promote anoximixis. Finally, we recommend that future research needs to test the predictions presented here to expand our understanding and management of anoximixis.