Challenges and opportunities for sustaining coastal
wetlands and oyster reefs in the southeastern United States
Estuaries in the southeastern United States, and around the world, are facing incredible challenges due to increasing pressures from population growth, development, fishing, recreation, and climate change.
This research quantified changes in population growth and land cover change in seventy-two coastal counties from Mississippi to North Carolina. Additionally, local experts contributed their own experiences of what they thought were the greatest threats to estuaries and oysters in an 'estuary expert survey.'
This storymap summarizes those findings. For the full paper, go to: https://doi.org/10.1016/j.jenvman.2021.113178
In the maps below, click on a county, state or the U.S. to see the changes in population.
Population Change 1996 - 2019 for Counties, States, and the U.S. Population data were downloaded from the U.S. Census .
Population change from 1996 - 2019 across the southeastern counties ranged from a loss of more than 7,000 residents in Monroe County, Florida, to a gain of more than 600,000 residents in Miami-Dade County, Florida. The average change for all counties in each state ranged from 3,245 in Mississippi to 105,044 in Florida, while the United States average was 18,723.
Population Percent Change 1996 - 2019 for Counties, States, and the U.S.
The percent change in population from 1996 - 2019 across the southeastern counties ranged from a loss of more than 16% in Monroe County, Florida to a gain of more than 170% in Miami-Date County, Florida. The average percent change for all counties in each state ranged from 9.8% in Mississippi to 48.7% in Florida, while the United States average was 21.8%.
Changes in population density per region (people per square kilometer)
While population density increased for all regions, South Florida and East Florida increased much more than did Alabama-Mississippi, Georgia, South Carolina, West Florida or North Carolina. South Florida increased from 179 people per square kilometer to 239 people per square kilometer, while North Carolina only increased from 21 to 29 people per square kilometer.
Changes in the amount of land cover (square kilometers) by type from 1996 to 2001, 2006, 2010, and 2016 (the periods of available data). Land cover data were provided by the NOAA C-CAP database.
Changes in land cover type show that the developed land cover type grew the most for all regions, though the land cover types with the most losses included undeveloped, agricultural and palustrine (freshwater) wetlands.
The amount of previously undeveloped land, converted to developed land (square meters), for each new resident to a region. Displayed as the change in the amount of converted land for each period of available NOAA C-CAP data.
As new residents moved into the regions, their preference for how much land they wanted to occupy changed significantly over time. From 2001 - 2006 their desire for land dropped, then grew again from 2006 to 2010, and dropped again from 2010 - 2016.
Results from the local expert survey indicate which local and climate related threats they felt were the most significant for area wetlands. Threat point is the average number of points selected by all local experts for that threat.
Survey respondents indicated that development and modifications to freshwater flow were the greatest threats to both wetlands and oyster reefs. Additionally, shoreline hardening was seen as the third most significant threat to wetlands.
Results from the local expert survey indicate which local and climate related threats they felt were the most significant for area oyster reefs. Threat point is the average number of points selected by all local experts for that threat.
In addition to development and modifications to freshwater flow, over harvesting was also seen as a significant local threat to oyster reefs.
Based on this research, the survival of estuaries and oyster reefs in the southeastern United States is most impacted by human development through conversion of undeveloped lands to developed lands, changes in freshwater flow, shoreline hardening, and over harvesting.
Keeping up with these changes in order to manage resources can be a challenge itself for local experts. To help keep up with these changes, there are several methods that could be provided to make this easier: more real time data that tracks changes in estuaries and oyster reefs from these threats; development of higher spatial and temporal resolution of habitat data; more support for longer project evaluation and project management; more communication of projects and findings between agencies, and academic and industry professionals; and ways to help communicate all of this to the public.
Like many other studies these days, this project also shows that the impact of humans on the natural environment is significant and not beneficial to it's persistence. The ability to sustain coastal estuaries and oyster reefs will likely require the collaboration and joining of resources across all sectors.
For the full article, go to: https://doi.org/10.1016/j.jenvman.2021.113178
