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SUSCEPTIBILITY OF A NORTHEASTERN GULF OF MEXICO ESTUARY TO HYPOXIA
Citation:
Hagy, J.D., III, J., M C. Murrell, J G. Campbell, AND J. Cherry, J.S., III. SUSCEPTIBILITY OF A NORTHEASTERN GULF OF MEXICO ESTUARY TO HYPOXIA. Presented at Estuarine Research Federation Conference, Seattle, WA, Sep 14-18, 2003.
Description:
Bottom water hypoxia is a common adverse consequence of nutrient enrichment in estuaries and coastal waters. To protect against hypoxia, it is helpful to know which waters are most susceptible to hypoxia. Hypoxia has been observed regularly in Pensacola Bay, a northeastern Gulf of Mexico estuary, both recently (1996-present) and in the past (1960's to 70's). However, this system is shallow ( mean depth = 3.4 m), and presently has low phytoplankton biomass (average chlorophyll-a = 5-10 micrograms/liter) and high water clarity (secchi depth = 2-3 m), suggesting it would not be likely to develop hypoxia. We examined the factors contributing to hypoxia formation in this system using hydrographic surveys, box models, and measurements of benthic and plankton metabolic rates. Pensacola Bay has high average vertical salinity stratification (average = 3 ppt/m) and localized areas with stronger stratification (>5ppt/m) which combined with high metabolic rates associated with warm water (10-32 deg C, average 24 deg C), may make this system particularly susceptible to hypoxia. These factors were explored and evaluated in the context of historical changes in Pensacola Bay and ecosystem dynamics in other estuaries in the northern Gulf of Mexico and elsewhere.