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Drivers of Variability of Diel-Cycling and Episodic Hypoxia In Northern Gulf of Mexico Estuaries
Citation:
Jarvis, B., D. Beddick, G. Craven, Rick Greene, Jim Hagy, J. Lehrter, M. Murrell, AND D. Yates. Drivers of Variability of Diel-Cycling and Episodic Hypoxia In Northern Gulf of Mexico Estuaries. 2016 Ocean Sciences Meeting, New Orleans, LA, February 21 - 26, 2016.
Impact/Purpose:
This abstract is submitted for presentation at the CERF conference held Nov 8-12 in Oregon. It will summarize results of field work from the ADOS project.
Description:
Eutrophication of coastal ecosystems is a longstanding environmental concern, exacerbated by population growth and associated nutrient pollution, and ultimately resulting in increased incidence of hypoxia. Shallow and highly productive estuaries and embayments are particularly susceptible to diel-cycling hypoxia, associated with day-night cycles of production and respiration, which can cause extreme excursions in dissolved oxygen (DO) concentrations from anoxia to super-saturation within a single day. Diel oxygen dynamics in these systems are complex, and may be influenced by wind forcing, vertical and horizontal mixing, variation in freshwater inflow, cloud cover, and temperature. To better understand the environmental drivers of periodic hypoxia, this study examined four northern Gulf of Mexico Estuaries (Weeks Bay, AL; Wolf Bay, AL; Fowl River, AL; and St. Louis Bay, MS). Dissolved oxygen varied strongly on a diel basis in all four systems, with periods of sustained low oxygen (>24 h) observed in both Weeks Bay and Wolf Bay. The duration and persistence of hypoxia further varied in response to changing salinity regimes and regional weather. These results underscore the dynamic nature of hypoxia in shallow estuarine systems, and highlight the importance of combining fixed site continuous monitoring data with spatial hydrographic surveys to accurately resolve DO dynamics.