A methodological evaluation of the determination of critical oxygen threshold in an estuarine teleost

• Published in: Biology Open
• Main Authors: Negrete, Benjamin, Esbaugh, Andrew J.
• Format: Text
• Language: English
• Published: The Company of Biologists Ltd 2019
• Subjects: METHODS AND TECHNIQUES; Red drum
• Online Access: http://bio.biologists.org/cgi/content/short/8/11/bio045310; https://doi.org/10.1242/bio.045310

One measure of hypoxia tolerance is the critical oxygen threshold, P crit , which is the point where standard metabolism can no longer be maintained through aerobic processes. Traditionally, P crit was determined using closed respirometry, whereby the fish's respiration naturally lowered O 2 . More recently, intermittent flow techniques have been adopted, where N 2 is used to displace O 2 , which ostensibly reduces end-product build-up. This study used a paired design on the marine teleost, red drum. P crit is comparable between closed (4.6±0.2 kPa; mean±s.e.m.) and intermittent flow (4.4±0.2 kPa; mean±s.e.m.) respirometry. pCO 2 , ammonia and pH changes within the chamber were measured prior to the onset of P crit and at the end of a typical P crit trial and revealed changes in water chemistry in both closed and intermittent flow. P crit values were similar in both methods of hypoxia induction regardless of subsequent water chemistry changes that occurred in both methods.