McGowan, David W.

This study determined the electrosensitivity of a euryhaline elasmobranch,
the Atlantic stingray, Dasyatis sabina, throughout the range of salinities that it
would naturally encounter. It quantified the behavioral response of the stingrays to prey-simulating electric stimuli in freshwater, brackish, and full strength
seawater. The electroreceptive capability of stingrays from a permanent
freshwater population in the St. Johns River system was also compared with
stingrays that inhabit the tidally-dynamic Indian River Lagoon in east Florida.
This study demonstrated that D. sabina can detect prey-simulating electric fields
in freshwater, but the function of its electrosensory system is significantly
reduced. The SJR stingrays did not demonstrate an enhanced electrosensitivity
in freshwater, nor did they have reduced sensitivity when introduced to higher
salinities. The reduction in electrosensitivity and detection range in freshwater is
attributed to both an environmental factor (electrical resistivity of the water) and
the physiological limitations of the ampullary canals.