Changing weather patterns and receding glaciers are predicted to increase flow intermittency in alpine streams. If aquatic macroinvertebrate communities largely comprise taxa adapted to perennial flows, an increase in flow intermittency substantially reduces biodiversity and affects functional processes. We conducted a before-after-control-impact field experiment to examine how macroinvertebrate communities in an alpine headwater stream responded to and recovered from a repeated experimental increase in flow intermittency. Flow in one channel was manipulated to simulate increased summer intermittency (June–September) over two consecutive years, whilst an adjacent channel served as a control. We monitored the density of benthic macroinvertebrates, periphyton and organic matter at approximately monthly intervals over three years during the snow-free period. Before manipulation, both channels had similar ecological properties. The flow manipulation reduced the overall macroinvertebrate density, and especially the proportional rheophile density, across both years. Recovery of the macroinvertebrate community following experimental flow intermittency took more than a year, and longer than our study period. This could be due to long aquatic life stages, dispersal limitation and biotic interactions. We conclude that climate-induced changes in alpine stream flow regimes can lead to a fundamental shift in macroinvertebrate assemblages through local extinctions, mostly of rheophilic species.

Accurate quantification of greenhouse gas (GHG) fluxes from aquatic systems is essential for constraining regional and global carbon budgets. Closed floating chambers are widely used to measure carbon dioxide (CO ₂ ) and methane (CH ₄ ) fluxes at the water–air interface, yet large uncertainties persist due to subjective processing of chamber time series. In particular, the treatment of nonlinear patterns and abrupt events such as ebullition often relies on expert judgment, which may strongly influence flux estimates. We present the first quantitative assessment of bias arising from expert subjectivity in the processing of floating chamber measurements. Seventeen researchers, all of whom participated in field sampling, independently evaluated a common dataset of 794 incubations from 36 European coastal wetlands. Each expert visually selected valid data segments and flagged abnormal time series prior to flux calculation. In total, 2679 manual inspections were compared with fully automated flux estimates based on untrimmed time series. Experts showed substantial variability in flagging abnormal measurements and handling nonlinear or irregular concentration patterns. While flux variability was generally low for most CO ₂ and CH ₄ incubations, disagreements exceeded 100% for curved or temporally complex time series. For CH ₄ , ebullition was a major source of divergence, but marked variability also occurred when ebullition contributed only marginally to total fluxes. This methodological experiment demonstrates that expert judgment introduces significant, previously unquantified uncertainty into aquatic GHG flux estimates. We advocate for transparent, standardized, and reproducible data‐processing workflows, including automated tools for objective identification and treatment of nonlinearities.

Coastal wetland restoration is widely promoted as a tool for climate change mitigation, but its effect on the carbon cycle is not well constrained. We conducted a systematic review and meta-analysis of peer-reviewed field studies that directly contrasted restored with altered sites, covering carbon stocks and greenhouse gas fluxes across mangroves, saltmarshes, seagrass meadows, brackish systems, and coastal freshwater wetlands. Literature searches yielded 66 studies and 257 pairwise restored versus altered site comparisons. Multilevel random-effects models with nested study effects showed significant increases after restoration in soil carbon, aboveground biomass, and belowground biomass. Mean greenhouse gas flux changes after restoration were non-significant for CO₂, CH₄, and N₂O. Meta-regressions detected no significant differences among wetland types, though this result is constrained by unbalanced evidence across systems and studied parameters. The available data are geographically biased toward tropical and subtropical Asia, with minimal coverage in Africa and limited data from temperate and cold coastal regions. Among the covered variables dissolved organic carbon is critically underrepresented, constraining whole-system impact estimates. Overall, the data examined in this study show that restoration consistently rebuilds biomass and soil carbon without a detectable systematic “cost” from methane or nitrous oxide, indicating positive outcomes for greenhouse gas fluxes. To translate these findings into policy-ready estimates, monitoring of greenhouse gases and dissolved organic carbon should be expanded, altered versus restored designs should be prioritized, and underrepresented regions and wetland types should be targeted.