Tolerance and Avoidance Behavior towards Gas Supersaturation in Rock Carp Procypris rabaudi with a History of Previous Exposure

Abstract

Total dissolved gas (TDG) supersaturation on the upper Yangtze River basin is becoming increasingly serious because of the intense construction of high dams, posing a threat to resident fish. The tolerance and behavior characteristics of Rock Carp Procypris rabaudi preexposed to TDG-supersaturated water were evaluated by placing juveniles (weight 6.4 ± 1.67 g, fork length 7.2 ± 0.7 cm; mean ± SD) in 35-cm-deep tanks at 130% supersaturation for 2.33 h as preexposure. Surviving fish were allowed 5 d of recovery in saturated-equilibrium (100% TDG) water and then examined in an acute lethality experiment at TDG supersaturation values of 120, 125, 130, 135, 140, and 145%. The resulting median lethal times were 10.4, 4.6, 3.2, 2.1, 1.4, and 1.4 h, respectively. The preexposed fish showed a poorer tolerance to TDG-supersaturated water than did a control group that were not preexposed for TDG above 120% supersaturation (P < 0.05 in cases where there was a significant difference between individual groups). Experiments on horizontal behavior and vertical behavior used the same preexposure routine, followed by 5 d of recovery in saturated-equilibrium water. For all behavior experiments, both the preexposed and control groups showed significant avoidance responses to TDG-supersaturated water; however, there were no significant differences between the preexposed and control groups.

Received February 24, 2015; accepted June 3, 2015

ACKNOWLEDGMENTS

This work was sponsored by the National Natural Science Foundation of China under permission number 51379136, and B. Hodges was partially supported by the U.S. National Science Foundation under grant CCF-1331610.