The low carbon dioxide
groupwas exposed to a slightly higher range (7–15 mg L−1) for the rest
of the experiment. On day 7, the carbon dioxide partial pressurewas increased
in the medium, high and very high carbon dioxide groups to
6.5 mmHg (17 mg L−1), 9.5 mmHg (25 mg L−1) and 10.9 mmHg
(29 mg L−1), respectively