Immediate and cumulative effects of nutrient and extreme weather disturbances on pond greenhouse gas emissions

Abstract Ponds are significant emitters of greenhouse gases (GHGs). While eutrophication stimulates GHG emissions, responses to nutrient pulses and weather events are less clear. We investigated both immediate and cumulative effects of experimental storm‐scale nutrient pulses, along with unplanned extreme heat and wind events during the experiment, on GHG fluxes in nutrient‐enriched ponds compared to reference ponds. Physical disturbances had greater immediate effects on GHG fluxes than did nutrient pulses due to effects on stratification and oxygen. Extreme heat increased CO 2 flux and methanogenesis potential, while extreme wind increased CO 2 flux. The combination of nutrients and extreme heat, however, triggered physicochemical changes that stimulated GHG emissions, doubling CH 4 efflux from nutrient‐enriched ponds prior to late‐summer mixing. Late‐summer emissions from reference ponds closed the gap in cumulative CH 4 and CO 2 efflux between treatments; however, suggesting that storm‐driven nutrient loading may not increase total within‐season GHG emissions from shallow aquatic systems.