Marshes to Mudflats: Climate Change Effects Along Coastal Estuaries in the Pacific Northwest
Marshes to Mudflats: Climate Change Effects Along a Latitudinal Gradient in the Pacific Northwest
Dates
Start Date
2012-05-30
End Date
2015-08-03
Release Date
2012
Summary
Over 50% of commercial and recreationally important fish species depend on coastal wetlands. In the Pacific Northwest, coastal wetlands, where the ocean meets the land, are highly productive areas that support a wealth of wildlife species from salmon to ducks. The tidal marshes, mudflats, and shallow bays of coastal estuaries link marine, freshwater, and terrestrial habitats and provide economic and recreational benefits to local communities. However, wetlands in this region and elsewhere are threatened by sea-level rise and other climate-related changes. According to a USFWS and NOAA report, between 2004 and 2009, 80,000 acres of wetland were lost on average each year, which is a significant increase from the previous six years. [...]
Summary
Over 50% of commercial and recreationally important fish species depend on coastal wetlands. In the Pacific Northwest, coastal wetlands, where the ocean meets the land, are highly productive areas that support a wealth of wildlife species from salmon to ducks. The tidal marshes, mudflats, and shallow bays of coastal estuaries link marine, freshwater, and terrestrial habitats and provide economic and recreational benefits to local communities. However, wetlands in this region and elsewhere are threatened by sea-level rise and other climate-related changes. According to a USFWS and NOAA report, between 2004 and 2009, 80,000 acres of wetland were lost on average each year, which is a significant increase from the previous six years.
While we know that these coastal ecosystems are already changing, we know comparatively less about how these areas might continue to change over the next 50 to 100 years. The goal of this project was to provide scientific information that will support long-term coastal planning and conservation efforts in the face of changing climate conditions. Researchers looked at the effects of sea-level rise on nine tidal marshes in Washington and Oregon. They compiled data on coastal terrain, tidal flooding, vegetation, and how quickly sediments accumulate, to assess how sea-level rise may alter these ecosystems in the future. Researchers found that factors such as elevation, sediments, and rate of sea-level rise can all affect marsh resilience. Importantly, researchers found that while most of the tidal marsh study sites will be able to persist in the face of sea-level rise over the next 50-70 years, sea-level rise could eventually outpace the growth of marshes and drown most high and mid-elevation marsh habitats by 2110.
In the Pacific Northwest, coastal wetlands support a wealth of ecosystem services including habitat provision for wildlife and fisheries and flood protection. The tidal marshes, mudflats, and shallow bays of coastal estuaries link marine, freshwater, and terrestrial habitats and provide economic and recreational benefits to local communities. Climate change effects such as sea-level rise are currently altering these habitats, but we know little about how these areas will change over the next 50-100 years. Our study examined the effects of sea-level rise on nine tidal marshes in Washington and Oregon, with the goal of providing scientific data to support future coastal planning and conservation. We compiled physical and biological data, including coastal topography, tidal inundation, vegetation structure, and current and historic sediment accretion rates to assess and model how sea-level rise may alter these ecosystems in the future. Multiple factors, including initial elevation, marsh productivity, sediment availability, and rates of sea-level rise affected marsh persistence. Under a low sea-level rise scenario, all marshes remained vegetated with little change in the present configuration of marsh plant communities or gradually increased proportions of mid, high, or transition marsh vegetation zones. However, at most sites mid sea-level rise projections led to the loss of middle and high marsh and a gain in low marsh habitat. Under a high sea-level rise scenario, marshes at most sites eventually converted to intertidal mudflats. Two sites (Grays Harbor and Willapa) appeared to have the most resilience to a high sea-level rise rate, persisting as low marsh until at least 2110. Our main model finding is that most tidal marsh study sites have resiliency to sea-level rise over the next 50-70 years, but that sea-level rise will eventually outpace marsh accretion and drown most high and mid marsh habitats by 2110.