A Comparison of Gill Respiratory Surface Area in Fish from Well-Oxygenated Waters of the North Atlantic versus Fish from the Eastern Tropical South Pacific Oxygen Minimum Zone

The total gill surface areas (TGSA's) of a fish from the normoxic eastern Long Island Sound and a congeneric fish from oxygen minimum zones (OMZ) along Chile were measured to qualitatively determine the extent to which these fish can tolerate hypoxia. The TGSA’s of the fishes were calculated to compare the morphologies of fish from marine environments with hypoxic oxygen concentrations against those from normoxic environments to test the prediction that fish from low to hypoxic levels of oxygen with a similar lifestyle have a larger TGSA than those from normoxic environments. The dimensions of the total gill respiratory surface area were derived from images taken via digital photography, digital light microscopy and imaging, and scanning electron microscopy and imaging.