Recovery Rate of a Salt Marsh From the 1700 CE Cascadia Subduction Zone Earthquake, Netarts Bay, Oregon

Peck, Erin K.; Guilderson, Thomas P.; Walczak, Maureen H.; Wheatcroft, Robert A.

doi:10.1029/2022gl099115

Cited by 3 publications

(1 citation statement)

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“…For example, Benson et al (2001) found a recovery time of roughly 100 years for Sitka spruce (Picea sitchensis) to recolonize sites following the 1700 earthquake. Recent work by Peck et al (2022) found a 200-year recovery post-CSZ rupture for high marsh at nearby Netarts Bay, Oregon. These recovery rates, however, depend significantly on the balance between relative interseismic SLR and overall sediment supply, which in the LCRE has greatly decreased over the past century (Gelfenbaum et al, 2001;Templeton & Jay, 2013).…”

Section: Habitat Successionmentioning

confidence: 99%

Impacts of a Cascadia Subduction Zone Earthquake on Water Levels and Wetlands of the Lower Columbia River and Estuary

Brand

Diefenderfer

O’Connor

et al. 2023

Geophysical Research Letters

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Subsidence after a subduction zone earthquake can cause major changes in estuarine bathymetry. Here, we quantify the impacts of earthquake‐induced subsidence on hydrodynamics and habitat distributions in a major system, the lower Columbia River Estuary, using a hydrodynamic and habitat model. Model results indicate that coseismic subsidence increases tidal range, with the smallest changes at the coast and a maximum increase of ∼10% in a region of topographic convergence. All modeled scenarios reduce intertidal habitat by 24%–25% and shifts ∼93% of estuarine wetlands to lower‐elevation habitat bands. Incorporating dynamic effects of tidal change from subsidence yields higher estimates of remaining habitat by multiples of 0–3.7, dependent on the habitat type. The persistent tidal change and chronic habitat disturbance after an earthquake poses strong challenges for estuarine management and wetland restoration planning, particularly when coupled with future sea‐level rise effects.

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Section: Habitat Successionmentioning

confidence: 99%

Impacts of a Cascadia Subduction Zone Earthquake on Water Levels and Wetlands of the Lower Columbia River and Estuary

Brand

Diefenderfer

O’Connor

et al. 2023

Geophysical Research Letters

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Spatiotemporal controls on organic matter sourcing to minerogenic salt marshes

Peck,

Goñi,

Wheatcroft

2024

Limnology & Oceanography

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Salt marshes are important carbon sinks; however, identification of the drivers of carbon burial rates is challenging because estuaries sit at terrestrial and marine interfaces. Here, we address the questions: what are the sources of organic matter sequestered in minerogenic salt marshes, and how do sources change through time? We characterized down‐core sediment biogeochemistry (C : N, δ13C, δ15N) for the last century in seven Oregon USA high marshes and used a mixing model to elucidate differences in organic matter sources across estuaries and through time. Autochthonous biomass production consistently accounted for only half of overall organic matter accumulation, and the remainder was allochthonous, originating from a combination of estuarine and terrestrial sources. Salt marshes with high sediment loads buried more terrestrial organic matter, whereas those with low loads and substantial subtidal habitat buried more estuarine‐derived organic matter. When assessed through depth/time, stable isotope trends indicated that decomposition is not the primary control. Instead, organic matter became increasingly more terrestrial in recent decades, especially in salt marshes with low fluvial loads. We hypothesize that salt marshes with lower loads took longer to regain lost elevation following coseismic subsidence of the 1700 ce Cascadia earthquake. This result magnifies the role of river floods in sediment and carbon accumulation on the marsh surface. Ultimately, the highest carbon burial rates coincided with highest fractions of terrestrially sourced organic matter, though spatiotemporal complexities obscured any potentially significant trends. While the term “blue” typically excludes terrestrial carbon, minerogenic salt marshes still perform the important ecosystem function of burying organic matter.

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