Uptake of Ions and Water by the Painted Turtle, Chrysemys picta

Abstract

The painted turtle, Chrysemys picta belli, loses sodium, calcium and potassium ions to its freshwater environment. Absorption of sodium and calcium but not potassium from freshwater media contributes toward salt balance in this species. Influx of water, however, is quantitatively a greater osmoregulatory problem to freshwater turtles than is loss of ions. Uncompensated water influx dilutes internal fluids by about 3% per day, whereas uncompensated sodium loss reduces sodium concentrations by only 0.2% per day.