Auburn research team to study the Mobile-Tensaw-Apalachee River Delta
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A research team from Auburn University at the College of Forestry, Wildlife, and Environment, or CFWE, has received a $459,482 grant from the U.S. Department of the Treasury in cooperation with the Department of Conservation and Alabama State Natural Resources and Alabama Center of Excellence at MESC/Dauphin Island Sea Lab.
Led by Principal Investigator Christopher Anderson, the grant will fund a study to assess the function and vulnerability of forested wetlands in the Mobile-Tensaw-Apalachee River Delta, or “MTA River Delta.”
Often referred to as the “American Amazon,” the MTA River Delta covers approximately 260,000 acres and is dominated by a complex network of tidal and non-tidal wetlands. The watershed that drains to the MTA River Delta is approximately 46,000 square miles and spans most of Alabama, including the drainage of the Alabama, Coosa, and Tallapoosa rivers.
Anderson, a professor of wetland ecology, will lead the study with a team of researchers that includes CFWE Auburn Professor Latif Kalin and Dauphin Island Sea Lab University of South Alabama Professor Ruth Carmichael.
“The delta is a formidable complex of wetlands of international importance; however, it remains largely understudied,” Anderson said. “The MTA has significant river flows that are strongly tied to tidal forested floodplain wetlands before draining into Mobile Bay. These wetlands likely make important contributions to the bay and its productivity.
The goal of the team’s research is to examine tidal forest wetlands in the MTA River delta and predict changes in the delta due to sea level rise and future river flows. Using a combination of field data and environmental modeling, the team will examine how proximity to Mobile Bay influences wetland hydrology, salinity, and forest communities.
“A total of nine salinity measurement stations and more than 40 forest survey plots will be established in the lower delta of the MTA to determine the types of forested wetlands and their sensitivity to sea level rise and salinity changes,” Anderson said.
The team will collect field data for approximately two years. The salinity and tidal connectivity data will be used with other existing long-term data to develop predictive models for each gauging station. Models of river salinity and tidal connectivity will be developed using artificial neural networks, or ANNs.
“ANN modeling is a data-driven approach that can help learn and map the complex relationships between inputs and outputs,” Anderson said. “These models will be used to predict the salinity and tidal connectivity of the MTA River delta based on expected changes in important input variables such as tide levels and river flow.”
The team also plans to characterize the relationship between river flows from the MTA and the extent of delta-derived organic matter to Mobile Bay.
There is uncertainty about the role the MTA delta plays in terms of exporting organic matter and nutrients to the large estuary, says Anderson. These materials can be very important to the aquatic productivity of Mobile Bay.
The collaboration with Carmichael and others at the Dauphin Island Sea Lab, or DISL, will bring technical expertise to the project that will allow the team to assess the influence of the delta for the first time.
“In collaboration with DISL, we will trace organic matter in the delta by measuring stable isotope ratios of carbon and nitrogen which can help us distinguish sources,” Anderson said.
“This approach will help us determine the role of the MTA River delta in exporting organic matter from different sources due to tidal connectivity and river flow.”
“There is an extremely urgent need to better understand the expected fate of the MTA River Delta as there are significant questions about its functional role in the larger Mobile Bay estuary,” said Janaki Alavalapati, Dean of CFWE. “Anderson’s research will help identify potential risks to this important coastal resource.”