Abstract
This research determined the current condition and function of the Mobile-Tensaw River Delta.
A combination of field data collection and modeling were used to characterize tidal freshwater
forested wetland (TFFW) hydrology, salinity, and vegetation along the tidal extent of three
distributary river/creeks in the Mobile-Tensaw River Delta. A total of 47 forest survey plots
(500-m 2 ) were stratified across different prominent forested wetland types and river reaches.
Data were used to calculate species importance values of canopy-sized tree species and assess
community assemblages related to tidal reach. Nine river-gaging water stations were established
along a forested tidal gradient and within the Mobile-Tensaw River Delta project area. At each
station, data loggers were used to continuously measure hourly water levels and salinity
(converted from conductivity) at the surface water inlets of TFFWs along the river-wetland
interface. Data were collected for approximately two years. Salinity data were used with other
existing long-term data (Mobile River flow, Mobile Bay tide and salinity, and other data from the
USGS, NOAA and other sources) to develop a 15-year hindcast salinity model for each gaging
station. River salinity models were developed using a hybrid deep neural network model with a
residual network technique to predict salinity dynamics at forest plots across the Mobile-Tensaw
River Delta.
Finally, there remains significant uncertainty about the role that TFFW contribute in terms of
export of organic matter (OM) and nutrients to the larger estuary. We utilized an isotopic
approach to assess spatial and temporal trends in OM composition related to changes in river
flow (and Mobile-Tensaw River Delta floodplain connectivity) and the OM sources to Mobile
Bay. Changes in OM composition in river floodplains and tidal systems typically accompany
changes in hydrology that affect salinity and nutrient regimes. These changes can be traced by
measuring organic carbon (C) and nitrogen (N) stable isotope ratios that distinguish freshwater
from marine influences and relative nutrient sources. We applied this approach to determine if
changes in Mobile-Tensaw River Delta wetland structure or function may change OM sources
due to tidal connectivity and river flows.
Purpose
Data were collected using forest plots (n=47) and water stations (n=9) established across the
freshwater tidal reach of the lower Mobile Tensaw River Delta. The purpose of these data were
1) to determine forest structural conditions based on canopy tree basal area (m2/ha) and density
(no. trees/ha) based on 400-m2 surveyed plots, 2) the composition of forest canopy species based
on relative density, relative dominance and importance value in these surveyed plots, and 3)
measure continuous salinity (psu) of waters flooding freshwater tidal swamps.
DOI: 10.57778/QWZQ-R614
Suggested Citation
Anderson, C., & Balder, A. (2026). Forest and salinity data across a tidal gradient in the lower Mobile Tensaw River Delta, USA [Data set]. Dauphin Island Sea Lab. https://doi.org/10.57778/QWZQ-R614
Related Publication Citation
- Balder, A., C.J. Anderson, and N. Billor. 2024. Tidal Freshwater Forested Wetlands in the Mobile-Tensaw River Delta along the Northern Gulf of Mexico. Forests 15(8), 1359. DOI: 10.3390/f15081359.
- Balder, A., T. Kosovo, C.J. Anderson, and L. Kalin. Using machine learning to evaluate woody plant species associations with salinity and hydrology across a tidal gradient in coastal Alabama. Estuarine, Coastal and Shelf Science (In press).
- Anderson, C.J., H. Tuite, and A. Balder. Surveying the range and habits of fiddler crabs across a freshwater tidal reach of the Mobile-Tensaw River Delta. Journal of Coastal Research (In press).
Attribution
This project was paid for [in part] with federal funding for the Alabama Center of Excellence from the Department of the Treasury under the Resources and Ecosystems Sustainability, Tourist Opportunities, and Revived Economies of the Gulf Coast States Act of 2012 (RESTORE Act) in cooperation with the State of Alabama Department of Conservation and Natural Resources under the Alabama Center of Excellence Program at the MESC/Dauphin Island Sea Lab.
ALCOE Grant #: MESC-ALCOE-07
