Osmoregulation in the Turtle Trionyx spiniferus from Brackish and Freshwater

Two populations of Trionyx spiniferus emoryi were collected in New Mexico and their ability to osmoregulate was studied. One population inhabits freshwater (total ions = 26.9 meq/liter) and the other inhabits brackish water (238.0 meq/liter). Turtles were maintained in laboratory water analogous to their field environments and then acclimated to tap water or brackish water. Blood analysis shows differences between the populations in urea, potassium and total osmotic concentration. Analysis of urine shows population differences in potassium, calcium, magnesium and total osmotic concentration.