Wetlands in intermittently closed estuaries can build elevations to keep pace with sea-level rise
2021
Abstract Sea-level rise is a threat to coastal ecosystems, which have important conservation and economic value. While marsh response to sea-level rise has been well characterized for perennially open estuaries, bar-built intermittently-closed estuaries and their sea-level rise response are seldom addressed in the literature – despite being common globally. Here, we show that annual closures can play a critical role in maintaining marsh elevations by trapping fluvial sediments that can accrete on the marsh plain. We seek to advance the conceptual understanding of sea-level rise response of marshes by incorporating the unique nature of intermittently-closed estuaries in a marsh model. We hypothesize that intermittently-closed-estuary marshes may be more resilient to sea-level rise than open-estuary marshes due to greater initial elevation capital and higher accretion rates due to closure events. Using California, USA as a case study, spatial analysis shows that marshes in intermittently-closed-estuaries had significantly greater elevations (x = 1.93 m ± 0.2 standard error, n = 14) than marshes in permanently open estuaries (x = 0.94 m ± 0.1 standard error, n = 8; P = 0.001). We then used a process-based model to determine marsh elevation change under 840 simulated responses to sea-level rise scenarios to 2100. Our modeling shows that regular annual mouth closure can promote accretion rates and increase marsh elevations fast enough to match even high rates of sea-level rise, as fluvial sediment pulses can be captured in the estuary. Modeled suspended sediment concentration had the strongest effect on accretion, followed by probability of annual mouth closure. Intermittently closed estuaries are critical environments where marshes may be sustained under high rates of sea-level rise, thus reducing the anticipated global loss of these important ecosystems. Our results demonstrate an important gap in the knowledge about marsh accretion and identifies research needs to inform coastal management.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
78
References
2
Citations
NaN
KQI