Modeled Sea Level Rise Impacts on Coastal Ecosystems at Six Major Estuaries on Florida’s Gulf Coast: Implications for Adaptation Planning

<div><p>The Sea Level Affecting Marshes Model (SLAMM) was applied at six major estuaries along Florida’s Gulf Coast (Pensacola Bay, St. Andrews/Choctawhatchee Bays, Apalachicola Bay, Southern Big Bend, Tampa Bay and Charlotte Harbor) to provide quantitative and spatial information on how coastal ecosystems may change with sea level rise (SLR) and to identify how this information can be used to inform adaption planning. High resolution LiDAR-derived elevation data was utilized under three SLR scenarios: 0.7 m, 1 m and 2 m through the year 2100 and uncertainty analyses were conducted on selected input parameters at three sites. Results indicate that the extent, spatial orientation and relative composition of coastal ecosystems at the study areas may substantially change with SLR. Under the 1 m SLR scenario, total predicted impacts for all study areas indicate that coastal forest (-69,308 ha; -18%), undeveloped dry land (-28,444 ha; -2%) and tidal flat (-25,556 ha; -47%) will likely face the greatest loss in cover by the year 2100. The largest potential gains in cover were predicted for saltmarsh (+32,922 ha; +88%), transitional saltmarsh (+23,645 ha; na) and mangrove forest (+12,583 ha; +40%). The Charlotte Harbor and Tampa Bay study areas were predicted to experience the greatest net loss in coastal wetlands The uncertainty analyses revealed low to moderate changes in results when some numerical SLAMM input parameters were varied highlighting the value of collecting long-term sedimentation, accretion and erosion data to improve SLAMM precision. The changes predicted by SLAMM will affect exposure of adjacent human communities to coastal hazards and ecosystem functions potentially resulting in impacts to property values, infrastructure investment and insurance rates. The results and process presented here can be used as a guide for communities vulnerable to SLR to identify and prioritize adaptation strategies that slow and/or accommodate the changes underway.</p></div

Tampa Bay Study Area SLAMM Results.

<p>(A) Bar graph of loss/gain of coastal ecosystems under 3 sea level rise scenarios. (B) Map of SLAMM results illustrating the change in coastal ecosystem types (from/to) under a 1 m sea level rise scenario.</p

Project study areas, subsites and vicinity maps.

<p>The project study areas and vegetation raster inputs are illustrated in color for all study areas. The vegetation raster inputs represent the initial condition of coastal ecosystems used in the SLAMM analyses. Subsites are identified within study areas by numbers 1–4. Subsites were created where tidal parameters vary substantially from the global site (unmarked area) or where freshwater flow is substantial as along some river floodplains. Vicinity maps for each project study area along the Florida Gulf Coast are provided next to each study area map.</p

Study Area Characteristics.

<p>^a Unknown.</p><p>^b Southern Big Bend is not an enclosed estuary. Open ocean areas adjacent to the coast are less than 3 m in depth.</p><p>^c This is likely an underestimate because seagrass has not been estimated in deeper waters due to insufficient water clarity.</p><p>Sources: [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132079#pone.0132079.ref007" target="_blank">7</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132079#pone.0132079.ref032" target="_blank">32</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132079#pone.0132079.ref044" target="_blank">44</a>].</p><p>Some characteristics of the 6 study areas are presented including area, mean inflow, mean depth, average salinity, great diurnal tide, extent of coastal wetlands and the type and extent of the predominant subtidal habitat (not including bare sediments).</p

Digital Elevation Model (DEM) inputs and NOAA tide stations utilized for all study areas.

<p>Tidal parameters and location of stations informed the creation of subsites for each study area as illustrated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132079#pone.0132079.g001" target="_blank">Fig 1</a>.</p

Bar graph of loss/gain of coastal ecosystems for all six study areas (summed).

<p>The SLAMM results illustrated in this bar graph are for the following 3 sea level rise scenarios: 0.7m, 1m, 2m. All scenarios were run with developed dry land protected from change in the SLAMM user interface.</p

St. Andrews/Choctawhatchee Bays Study Area SLAMM Results.

<p>(A) Bar graph of loss/gain of coastal ecosystems under 3 sea level rise scenarios. (B) Map of SLAMM results illustrating the change in coastal ecosystem types (from/to) under a 1 m sea level rise scenario.</p

Quantitative SLAMM Results–coastal ecosystem change under a 1 meter SLR scenario through the year 2100, developed dry land protected from changing.

<p>¹Results exclude tidal flats with no elevation data (approximately 10,000 ha).</p><p>Quantitative SLAMM Results–coastal ecosystem change under a 1 meter SLR scenario through the year 2100, developed dry land protected from changing.</p

Parameters and their statistical distribution input into the SLAMM uncertainty analysis module.

<p>U = Uniform distribution (minimum, maximum); T = Triangular distribution (minimum, most likely, maximum).</p

Charlotte Harbor Study Area SLAMM Results.

<p>(A) Bar graph of loss/gain of coastal ecosystems under 3 sea level rise scenarios. (B) Map of SLAMM results illustrating the change in coastal ecosystem types (from/to) under a 1 m sea level rise scenario.</p