Salt marshes of the Gulf Coast (North American Atlantic & Gulf Coastal Salt Marsh – USNVC D034) provide important ecological and ecosystem services, including habitat for migratory shore birds, shellfish, fish, and protection from coastal storms. Yet these salt marshes continue to decline in acreage. Contributing factors include coastal storms and sea-level rise, which, when coupled with other stressors, such as lack of freshwater sediments and land subsidence from extractive industries, increases the salt-water inundation, and leads to collapse and conversion to deepwater bay bottoms or open ocean. Given these pressures, substantive efforts are being put into a wide variety of monitoring programs to track the condition and restoration of salt marshes, including through the Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA). These programs are largely uncoordinated, leading to gaps in our ability to assess Gulf-wide patterns. Our objective is to identify efficient indicators and empirical thresholds useful for managing salt marshes and which can be implemented by monitoring programs across the Gulf. Our approach was to use an expert-driven process to develop a set of indicators and thresholds directly linked to the resilience of native salt marshes.
We held a NOAA-funded workshop to develop conceptual ecological models that show the relationship between both biotic and abiotic factors and the ecological integrity and ecosystem services of Gulf Coast salt marshes. An interdisciplinary team of Gulf Coast ecosystem experts reviewed the draft model and indicators. Using their input, we identified the preferred indicators and thresholds that track both the decline and recovery of existing salt marshes and the potential for formation of novel types. We assessed the degree to which data needed for the preferred indicators identified through our process are currently being collected by existing monitoring programs across the Gulf. We will provide recommendations for improving the data collected by those programs.
Given the many challenges facing coastal salt marshes, their decline and restoration may follow natural successional pathways or lead to alternative, novel salt marsh ecosystems. We demonstrate how our models and indicators will allow us to track these types of changes and how that might affect the ecological integrity and services of Gulf Coast salt marshes.