Date of Award

Spring 2012

Document Type

Legacy Thesis

Degree Name

Master of Science in Coastal Marine and Wetland Studies

Department

Coastal and Marine Systems Science

College

College of Science

First Advisor

Kehui (Kevin) Xu

Second Advisor

Paul T. Gayes

Third Advisor

Varavut Limpasuvan

Abstract

Scientists have become increasingly aware of hypoxic waters and the impact of hypoxia on biota. Hypoxia is reported at more than 400 systems all over the world and more frequently than in the past. Hypoxia can potentially cause habitat loss, stress marine organisms, degrade the health of the impacted ecosystems and affect commercial harvests. Hypoxia is controlled by physical, biological, chemical, and geological factors. Hypoxia in Long Bay, South Carolina, offshore of Myrtle Beach, was first observed in 2004 when high catches of flounder were reported. Based on five year time-series (every 15 minutes) ocean observations, low oxygen conditions have been found during nearly every summer between 2007 and 2011 in the coastal waters of Myrtle Beach South Carolina. Observational and modeling data were used to analyze the atmospheric and oceanic controls on the formation of hypoxia. A periodicity analysis was preformed on the oxygen data, showing two distinct periodicities: one at 1 cycle per day (a diurnal cycle from solar radiation) and the other at ~1.9 cycles per day (a semi-diurnal cycle from tides). Three- dimensional atmospheric (Weather Research and Forecast model, WRF) and ocean circulation (HYbrid Coordinate Ocean Model, HYCOM and Regional Ocean Modeling System, ROMS) models were used to investigate wind variability and ocean circulation, with special focuses on upwelling and stratification/mixing before, during and after severe hypoxia events in August and September 2009. Based on these analyses, three conceptual scenarios were proposed to investigate how hypoxia potentially develops in the coastal water of Myrtle Beach, South Carolina.

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