Oyster habitat suitability modeling for the Alabama Barrier Island restoration assessment at Dauphin Island
Dates
Publication Date
2020-02-26
Time Period
2019
Citation
Wang, H., Enwright, N.M., Soniat, T.M., Hermann, J.E., LaPeyre, M.K., Kim, S.-C., Bunch, B., Stelly, S.J., Dalyander, P.S., and Mickey, R.C., 2020, Oyster habitat suitability modeling for the Alabama Barrier Island restoration assessment at Dauphin Island: U.S. Geological Survey data release, https://doi.org/10.5066/P9O30XMZ.
Summary
A spatially explicit oyster habitat suitability index (HSI) model was developed for the Alabama barrier island restoration assessment at Dauphin Island. Based on previous oyster habitat suitability studies, seven water quality variables were selected and their relationships with habitat suitability were developed and incorporated into the oyster HSI model for Dauphin Island restoration assessment: 1) mean salinity, 2) minimum monthly mean salinity, 3) annual mean salinity, 4) annual mean dissolved oxygen, 5) annual mean total suspended solids, 6) annual mean water depth, and 7) annual mean water temperature. The final HSI score was calculated using the weighted geometric mean of the suitability scores of these individual variables. [...]
Summary
A spatially explicit oyster habitat suitability index (HSI) model was developed for the Alabama barrier island restoration assessment at Dauphin Island. Based on previous oyster habitat suitability studies, seven water quality variables were selected and their relationships with habitat suitability were developed and incorporated into the oyster HSI model for Dauphin Island restoration assessment: 1) mean salinity, 2) minimum monthly mean salinity, 3) annual mean salinity, 4) annual mean dissolved oxygen, 5) annual mean total suspended solids, 6) annual mean water depth, and 7) annual mean water temperature. The final HSI score was calculated using the weighted geometric mean of the suitability scores of these individual variables. The oyster HSI model was calibrated and validated using field data on oyster density from the Alabama Department of Conservation and Natural Resources (ADCNR) Marine Resources Division (MRD and continuous water quality data from the Mobile Bay National Estuary Program. Then, the oyster HSI model was used to assess oyster habitat suitability changes with and without restoration under future storminess and sea level (SL) conditions. The barrier island restoration actions being assessed include beach and dune restoration, marsh restoration, and placement of sand in the littoral zone. The storminess bins included realizations with a "medium" storminess, which included 1 to 3 storms over a 10-year period (that is, ST2) and a "high" storminess, which included 4 to 5 storms over an equal period (that is, ST3). The two future sea levels included a SL of 0.3 m (that is, SL1) and a SL of 1.0 m (that is, SL3) above the contemporary SL. Specifically, the medium storminess was paired with the 0.3 m above the contemporary SL (that is, ST2SL1) and the “high” storminess bin was paired with the 1.0 m above the contemporary SL (that is, ST3SL3). To account for intertidal marsh vertical accretion as a component of marsh morphology evolution, two scenarios were included in modeling: the U.S. Army Corps of Engineers (USACE) high and intermediate SLR curves in which marsh kept pace with SLR through accretion (1 cm/yr) through 2022 under high SLR curve whereas marsh kept pace with SLR by accretion for the entirety of the USACE intermediate curve. Inputs of water quality conditions under future storminess and sea level conditions were provided by the CE-QUAL-ICM model that was coupled with a geomorphology model and a hydrodynamic model. This data release includes simulation results and metadata of oyster habitat suitability scores at each spatial unit (grid cell) across the study domain: estuarine waters near Dauphin Island.
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Related External Resources
Type: Related Primary Publication
Enwright, N.M., Wang, H., Dalyander, S.P., and Godsey, E., eds., 2020, Predicting barrier island habitats and oyster and seagrass habitat suitability for various restoration measures and future conditions for Dauphin Island, Alabama: U.S. Geological Survey Open-File Report 2020–1003, 99 p.
This data release provides the details on the calculations of oyster habitat suitability index values across the model domain and final model outputs. The HSI model simulations include eight scenarios for each of the six restoration actions and the future-without action: ST2SL1 under USACE high SLR curve and intermediate curve for initial year (Yr = 0) and a period after 10 years (Yr = 10), and ST3SL3 under USACE high SLR curve and intermediate curve for initial year (Yr = 0) and a period after 10 years (Yr = 10). There is a total of 60 simulation runs. Values of each habitat suitability variable from water quality model monthly output for the cells in the water quality grid were calculated using the Esri ArcMap 10.7.1 for each simulation run. Landscape position-based habitat model outputs were used to calculate the mean water depth. A Python script (Python 2.7) was developed to read in the value of each habitat suitability parameter in spatial layers of the habitat suitability variables, calculate the individual suitability index based on the habitat suitability curves and determine the total habitat suitability index using the weighted geometric mean method, classify the suitability scores (0 to 1) into groups, and generate spatial a distribution map of oyster habitat suitability designations (that is, unsuitable, marginally suitable, suitable, and highly suitable).
