Climate Change Vulnerability Assessment and Adaptation Opportunities for Salt Marsh Types in Southwest Florida
The Charlotte Harbor National Estuary Program (CHNEP) conducted a vulnerability assessment project to identify the extent and nature of salt marshes and the adaptation of salt marshes to climate change. The salt marsh community of the Southwest Florida Ecosystem is one of the most unique salt marsh systems in the United States.
The subtropical climate of Florida supports a combination of temperate salt marsh vegetation and tropical mangroves that intermix to form an important transitional ecotone. These ecosystems are subject to extremes of temperature, salinity, winds, evaporation, and storm and provide many ecosystem services including:
- A base of the estuarine detrital food pathway.
- Nurseries and escape from predation habitat for many species of aquatic life including the early life stages of game fish and commercial fish.
- Recreational fishing.
- Commercial fishing and harvesting.
- Hunting.
- Migratory bird habitat.
- Ecotourism activities such as bird watching and kayaking.
- Carbon sequestration.
- Storm protection.
- Water quality treatment.
- Stabilization of sediment and shorelines.
- Increases in market-based property appraisal values.
- Aesthetic values.
From existing scientific literature, southwest Florida salt marsh provides habitat to a variety of resident and transient organisms including 301 plant species, 422 invertebrate species, 217 fish species, 11 amphibians, 31 reptiles, and 15 mammals; including 6 federally listed and 27 state listed animal species.
Mangroves primarily dominate the CHNEP shoreline (Drew and Schomer 1984). Monotypic stands of black needlerush (Juncus roemerianus) are more common in slightly elevated areas with lower ranges of tidal inundation and dominate salt marsh communities around the mid-estuarine transition zones at the mouths of rivers (e.g., Myakka and Peace Rivers) and creeks (Hancock). Parts of the interior habitat of Sanibel Island have bands of salt marsh dominated by Baker’s cordgrass (Spartina bakeri) and leather fern (Acrostichum aureum and A. danaeifolium).
Although almost 74 percent of salt marsh habitat is protected in the CHNEP, habitat continues to be lost to human-induced impacts including development, alterations of hydrology, and pollution. Salt marshes in Charlotte Harbor Estuary have been directly destroyed or impacted from construction activities for residential and commercial purposes including construction for seawalls, drainage ditches for agriculture and mosquito control, boat facilities, and navigation channels. Man-made hydrological alterations have reduced the amount of freshwater flow from some rivers (e.g., Peace, Myakka), while artificially increasing the flow through others (e.g., Caloosahatchee).
The primary focus of the CHNEP report is to:
- Inventory and determine the areal extent of salt marsh types throughout the CHNEP study area.
- Determine the vulnerability of those marshes to climate change.
- Identify the need and opportunities for avoidance, minimization, mitigation, and adaptation (AMMA) to climate change.
- Recommend strategies to implement alternate AMMA.
This report is designed for local for use by governments, stakeholder groups and the public at large in developing coastal and land use planning, and avoidance, minimization, mitigation and adaptation of climate change impacts to salt marshes throughout the CHNEP study area.