The Role of Stratification in the Deoxygenation of Mobile Bay and Adjacent Shelf Bottom Waters

Abstract

Oxygen depletion in the shallow bottom waters of Mobile Bay, Alabama, and in adjacent nearshore and continental shelf waters, is shown to be directly related to the intensity of water column stratification. Low winds speeds are coincidental with the onset of water column stratification and the occurrence of hypoxic events. Hourly, daily, and seasonal changes in the relationship between percent oxygen saturation or oxygen concentration in the bottom waters and surface-bottom density differences indicate that the oxidized materials are recently formed, and not relic or overwintering carbon sources. The influence of density structure (water column stratification) in other oxygen-depleted coastal water masses is compared to Mobile Bay.