Citation:

LEE, II, H., C. A. BROWN, C. Janousek, P. J. CLINTON, D. R. YOUNG, D. REUSSER, AND R. Loiselle. Keeping your seed head above water - EPA's research on the effects of sea level rise on sea grasses and emergent marshes in the Pacific Northwest. Presented at Coastal Wetlands Data and Information Workshop, Newport, OR, April 19 - 20, 2010.

Impact/Purpose:

Global climate change, including sea-level rise (SLR), will have profound effects on estuarine fish, shellfish, and wildlife populations and their habitats. To develop an understanding of these potential impacts, the U.S. EPA at Newport, Oregon is participating in a joint research project with the USGS, Oregon Climate Change Research Institute, U.S. Fish and Wildlife, U.S. Dept. of Agriculture, U.S. Forest Service, The Nature Conservancy, and Oregon State University. The overall objective of this multi-agency research is to develop the baseline climatic and biological data, models, and tools to predict the cumulative impacts of climate change on habitats and ecosystem services in coastal estuaries of the Pacific Northwest (PNW). One thrust of the research is to compare the predicted effects of SLR on wetland habitats from a widely used model, SLAMM, to those from a detailed, site-specific model for the Yaquina Estuary, Oregon. SLAMM is based on the National Wetland Inventory (NWI) classes and thus can be applied to most estuaries in the Pacific Northwest. However, SLAMM groups emergent marsh assemblages into very broad categories, makes a number of simplifying assumptions regarding changes in salinity patterns in response to SLR, and does not predict effects on submerged aquatic vegetation (SAV) such as Zostera marina beds. To generate more detailed predictions on emergent marshes, the EPA has or is planning to: 1) develop models to predict changes in estuarine salinity and other water quality parameters in response to SLR; 2) conduct field studies to determine the spatial and temporal patterns in salinity resulting from high tide water flooding intertidal emergent marshes; and 3) map emergent marsh species and assemblages with the objective of developing niche models to predict their distributions under altered environmental conditions. For the seagrasses, the EPA is developing a bathymetrically-based response model that builds off of more than a decade of research on the distribution and limiting factors for both the native Z. marina and non-native Z. japonica. Under the simplest assumption of a rise in sea level with no landward migration of the intertidal zone, preliminary model results predict that the area of Z. marina will increase with SLR up to about 1 m. However, it is likely that intertidal geomorphology will more or less re-equilibrate after SLR subject to the constraints of shoreline barriers and sediment accumulation rates. Both of these constraints are likely to be important limiting factors to the intertidal geomorphology re-equilibrating in many areas. Future development of the seagrass model will attempt to incorporate these factors on a site-specific basis, with the ultimate objective of developing a generalized seagrass model that could be coupled with SLAMM.

Description:

Global climate change, including sea-level rise (SLR), will have profound effects on estuarine fish, shellfish, and wildlife populations and their habitats. To develop an understanding of these potential impacts, the U.S. EPA at Newport, Oregon is participating in a joint research project with the USGS, Oregon Climate Change Research Institute, U.S. Fish and Wildlife, U.S. Dept. of Agriculture, U.S. Forest Service, The Nature Conservancy, and Oregon State University. The overall objective of this multi-agency research is to develop the baseline climatic and biological data, models, and tools to predict the cumulative impacts of climate change on habitats and ecosystem services in coastal estuaries of the Pacific Northwest (PNW). One thrust of the research is to compare the predicted effects of SLR on wetland habitats from a widely used model, SLAMM, to those from a detailed, site-specific model for the Yaquina Estuary, Oregon. SLAMM is based on the National Wetland Inventory (NWI) classes and thus can be applied to most estuaries in the Pacific Northwest. However, SLAMM groups emergent marsh assemblages into very broad categories, makes a number of simplifying assumptions regarding changes in salinity patterns in response to SLR, and does not predict effects on submerged aquatic vegetation (SAV) such as Zostera marina beds. To generate more detailed predictions on emergent marshes, the EPA has or is planning to: 1) develop models to predict changes in estuarine salinity and other water quality parameters in response to SLR; 2) conduct field studies to determine the spatial and temporal patterns in salinity resulting from high tide water flooding intertidal emergent marshes; and 3) map emergent marsh species and assemblages with the objective of developing niche models to predict their distributions under altered environmental conditions. For the seagrasses, the EPA is developing a bathymetrically-based response model that builds off of more than a decade of research on the distribution and limiting factors for both the native Z. marina and non-native Z. japonica. Under the simplest assumption of a rise in sea level with no landward migration of the intertidal zone, preliminary model results predict that the area of Z. marina will increase with SLR up to about 1 m. However, it is likely that intertidal geomorphology will more or less re-equilibrate after SLR subject to the constraints of shoreline barriers and sediment accumulation rates. Both of these constraints are likely to be important limiting factors to the intertidal geomorphology re-equilibrating in many areas. Future development of the seagrass model will attempt to incorporate these factors on a site-specific basis, with the ultimate objective of developing a generalized seagrass model that could be coupled with SLAMM.

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