Red Tide Water Quality Assessment Research Cruise

Preliminary Results

The cruise documented a large area of low dissolved oxygen at the bottom of the water column on the southwest Florida shelf. At its strongest, oxygen values were below 2mg/l in the bottom water layer, which was approximately 3-4 meters thick. The area less than 3mg/l of dissolved oxygen was approximately 1,400 km2 and the area less than 5mg/l of dissolved oxygen was a pproximately 8,500 km2.

NOAA's Atlantic Oceanographic and Meteorological Laboratory is conducting a South Florida Ecosystems research cruise aboard the R/V Walton Smith to help sample the ongoing red tide on the southwest Florida Shelf. The focus will be on quantifying human health and ecosystem impacts from the red tide event.

This hypoxic area was at the bottom of a stratified water column with significant changes in temperature and salinity from the top to bottom. The changes in temperature and salinity cause significant differences in density that prevent mixing between the top and bottom of the water. These changes in density shown below may have been the result of upwelling of water onto the west Florida shelf from the Gulf of Mexico.