How Did Hurricane Harvey Affect Oxygen and Nutrient Dynamics over the Texas Shelf?

Piers Chapman, Texas A&M University College Station, Oceanography, College Station, TX, United States, Steven Francis DiMarco, Texas A&M University, Geochemical and Environmental Research Group (GERG), College Station, United States, Anthony Hayden Knap, Texas A&M University, Geochemical and Environmental Research Group (GERG), College Station, Texas, United States and Henry Potter, Texas A&M University, Department of Oceanography, College Station, TX, United States
Abstract:
Hurricane Harvey brought torrential rain to the northern coastline of the Gulf of Mexico in late summer 2017. It was anticipated that the resulting stratification would result in a phytoplankton bloom that could lead to hypoxia below the pycnocline along the Texas shelf.

We report data from four cruises along the Texas shelf in summer/fall 2017: June (upwelling-favorable), August (post-upwelling), September (immediately following Hurricane Harvey) and November (post-storm recovery period). In June, coastal waters were stratified and showed depleted, although non-hypoxic, oxygen concentrations, but by August the stratification was breaking down. The rainfall from Hurricane Harvey restratified the shelf from Galveston Bay to south of Corpus Christi, but despite the volume of the runoff, nutrient concentrations remained low and bottom oxygen concentrations were higher than in June. By November, well-mixed conditions were found along the shelf with a strong onshore-offshore salinity gradient, but little evidence of depleted oxygen, and nutrient concentrations were back to normal relative to historic data.

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