Variation in Major Ion Concentration of<i>Cambarus robustus</i>and<i>Orconectes rusticus</i>Following Exposure to Low pH

Abstract

Cambarus robustus is more tolerant of low environmental pH than Orconectes rusticus and this tolerance reflects a difference in ion regulation physiology. Chronic exposure (96 h) of the acid-tolerant C. robustus to pH 3.8 soft water did not significantly change haemolymph [Na + ] or [Ca 2+ ] of the adults or total body [Na + ] of the juveniles relative to the control (pH 6.5). In contrast, the intolerant O. rusticus showed a significant decrease in [Na + ] and increase in [Ca 2+ ] in adult haemolymph (Wood and Rogano. 1986. Can. J. Fish. Aquat. Sci. 43: 1017–1026) and an increase in total body [Na + ] of stage III juveniles following acute exposure to pH 3.8 compared with the pH 6.5 control.