Drying and rewetting of riverbed sediments results in cold to neutral biogeochemical moments

Abstract

Abstract River corridors play a key role in global biogeochemical cycling, with riverbed sediments often accounting for over 90% of ecosystem respiration. Sediment respiration has been mostly studied in perennial streams, despite over 60% of streams globally being non-perennial. Previous experiments observed that sediment respiration response to rewetting varies from hot moments (i.e., bursts of increased respiration) to cold moments (i.e., decreased respiration), necessitating further research to understand the range of responses across diverse stream ecosystems. Here, we focused on O2 consumption as a key process tied to microbial respiration. We conducted manipulative wet/dry experiments with riverbed sediments from 50 streams within the contiguous United States. Results show that drying and rewetting sediments leads to cold or neutral moments of O2 consumption rates, rather than hot moments. We found that sediment texture and microbial activity were key factors influencing responses to rewetting. We propose a conceptual model, integrating across studies, whereby both hot and cold moments can exist simultaneously upon rewetting by considering both dry-state and perennially-inundated reference points. Future studies should test this by accounting for both reference points for holistic understanding of biogeochemical impacts of non-perennial flow on sediment respiration.

The authors' abstract, as published at the source. Communications Earth & Environment, 2026 · DOI ↗