Physical-biogeochemical response to climate change and sea level rise in the Mobile Bay, Alabama

Abstract:

Determining physical and biogeochemical changes in estuaries that will result from various aspects of climate change is of critical importance to understanding subsequent ecosystem and biological community impacts. Climate change is likely to alter precipitation and wind patterns, which in turn will affect river discharge and wind-driven circulation in the northern Gulf of Mexico, yet the regional impact of future climate conditions on estuarine physical and biogeochemical processes are not well characterized. Mobile Bay is a large estuary in the northern Gulf of Mexico and is classified as a microtidal, shallow, stratified and river-dominated system, where wind forcing contributes mixing and subtidal exchange. Hence, changing river discharge and wind patterns due to climate change together with sea level rise will likely alter the circulation and mixing patterns in the bay and, thus, the concentrations and rates of biogeochemically important constituents. Therefore, to understand the impacts of climate change and sea level rise on the physical and biogeochemical processes in Mobile Bay and adjacent coastal waters, a validated one-way coupled physical-ecological (ROMS-CGEM) model covering the region was applied to predict the response of estuarine processes including tidal and subtidal circulation, vertical stratification, transport and mixing of nutrient, organic matter, and phytoplankton concentrations, and hypoxia development to changing river discharge, wind patterns and sea level rise. The results from this work will reveal the relative importance of climate change in relation to natural variability and improve our understanding and predictions of how the Mobile Bay’s physical and biogeochemical characteristics evolve in the future.