Insights into estuary habitat loss in the western United States using a new method for mapping maximum extent of tidal wetlands

PLoS One. 2019 Aug 14;14(8):e0218558. doi: 10.1371/journal.pone.0218558. eCollection 2019.

Abstract

Effective conservation and restoration of estuarine wetlands require accurate maps of their historical and current extent, as well as estimated losses of these valued habitats. Existing coast-wide tidal wetland mapping does not explicitly map historical tidal wetlands that are now disconnected from the tides, which represent restoration opportunities; nor does it use water level models or high-resolution elevation data (e.g. lidar) to accurately identify current tidal wetlands. To better inform estuarine conservation and restoration, we generated new maps of current and historical tidal wetlands for the entire contiguous U.S. West Coast (Washington, Oregon, and California). The new maps are based on an Elevation-Based Estuary Extent Model (EBEEM) that combines lidar digital elevation models (DEMs) and water level models to establish the maximum historical extent of tidal wetlands, representing a major step forward in mapping accuracy for restoration planning and analysis of wetland loss. Building from this new base, we also developed an indirect method for mapping tidal wetland losses, and created maps of these losses for 55 estuaries on the West Coast (representing about 97% of historical West Coast vegetated tidal wetland area). Based on these new maps, we estimated that total historical estuary area for the West Coast is approximately 735,000 hectares (including vegetated and nonvegetated areas), and that about 85% of vegetated tidal wetlands have been lost from West Coast estuaries. Losses were highest for major river deltas. The new maps will help interested groups improve action plans for estuarine wetland habitat restoration and conservation, and will also provide a better baseline for understanding and predicting future changes with projected sea level rise.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • California
  • Conservation of Natural Resources*
  • Ecosystem*
  • Environmental Monitoring / methods*
  • Environmental Monitoring / standards
  • Estuaries*
  • Models, Theoretical
  • United States
  • Washington
  • Wetlands*

Grants and funding

LSB was funded as a subcontractor by a Multistate Conservation Grant to the Pacific States Marine Fisheries Commission (PSMFC) from the Association of Fish and Wildlife Agencies and the US Fish and Wildlife Service (Grant ID: NFHP-2155). KO received funding as a subcontractor through a grant to PSMFC from The Nature Conservancy (managed by WH). LSB (subcontractor), AL, TH, and RD received funding to complete the original development of the methods through the NOAA Office for Coastal Management through a Project of Special Merit Grant (award NOS4192014).