Table 2.

Results of repeated testing of the behavioral response of one S. histophorus to the experimental introduction of gas phases (20 ml) of different PO2 into the laboratory burrow system

Fish behavior
Gas-phase PO2 (kPa)Minimum response time (min)No. testsGas-phase removalGas addition
01211110
2.1223660
2.6334110
3.11,458220
4.131110
5.2537330
6.2642110
7.3727330
8.3133220
9.336220
10.413404
20.7248202
  • On each day of an experimental period, 1-8 gas phases were presented to the fish (depending on how rapidly the fish removed each phase). The sequence on day 1 of gas-phase testing is indicated by the superscript numbers next to the gas-phase PO2 values. For example, tests on that day began with a gas phase of 3.1 kPa, followed by a 2.1 kPa gas phase, etc. Two gas phases of 3.1 kPa (the first phase and the fourth) were introduced on day 1.