Aquatic Sciences Meeting, Albuquerque 2001

PC03 Undergraduate Education

Date: Tuesday, February 13, 2001

Location: Southwest Hall

Nord, A, S, Carleton College, 300 North St., Northfield, MN 55057 & University of Delaware, Lewes, DE 19958, , USA, norda@carleton.edu

HYPOXIA AND JUVENILE WINTER FLOUNDER (PSUEDOPLEURONECTES AMERICANUS): EFFECTS OF ADAPTATION TO LOW DISSOLVED OXYGEN ON METABOLIC RATE AND 02 UPTAKE DYNAMICS

Many fishes are estuarine-dependent in early life stages, when they are at risk to hypoxia exposure. Little is known about their abilities to adapt to chronic low oxygen concentrations. This study investigated changes in metabolic rate, oxyregulation, and critical oxygen tension in juvenile winter flounder. The fish were held at three treatment levels: 7.0, 3.5, and 2.0 mg O2/l. Fish in the 2.0 mg O2/l hypoxia treatment experienced 69% mortality, indicating that this is at or near the lower lethal limit. Mean metabolic rates above critical oxygen tension were not found to be significantly different between the oxygen-saturated treatment group and the group held at 3.5 mg O2/l. Fish in both treatment groups showed imperfect oxyregulatory ability as DO decreased. However, juvenile winter flounder held at oxygen-saturated conditions exhibited a critical oxygen tension significantly higher than fish acclimated to hypoxic conditions. Hypoxia-acclimated fish showed a 35% higher oxygen uptake rate than fish acclimated to oxygen-saturated conditions. These results show that juvenile winter flounder are able to adapt physiologically to hypoxia, and that they exhibit a tolerance to chronic hypoxia exposure.

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Aquatic Sciences Meeting, Albuquerque 2001

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