Effects of temperature on acid-base regulation, gill ventilation and air breathing in the clown knifefish, Chitala ornata

Le Thi Hong Gam, Do Thi Thanh Huong, Dang Diem Tuong, Nguyen Thanh Phuong, Frank Bo Jensen, Tobias Wang, Mark Bayley*

*Corresponding author for this work

Research output: Contribution to journalComment/debateResearchpeer-review

Abstract

Chitala ornata is a facultative air-breathing fish, which at low temperatures shows an arterial PCO2 (PaCO2) level only slightly elevated above that of water breathers. By holding fish with indwelling catheters at temperatures from 25 to 36°C and measuring blood gasses, we show that this animal follows the ubiquitous poikilotherm pattern of reducing arterial pH with increasing temperature. Surprisingly, the temperature increase caused an elevation of PaCO2 from 5 to 12 mmHg while the plasma bicarbonate concentration remained constant at around 8 mmol l−1. The temperature increase also gave rise to a larger fractional increase in air breathing than in gill ventilation frequency. These findings suggest that air breathing, and hence the partitioning of gas exchange, is to some extent regulated by acid-base status in air-breathing fish and that these bimodal breathers will be increasingly likely to adopt respiratory pH control as temperature rises, providing an interesting avenue for future research.

Original languageEnglish
Article number216481
JournalJournal of Experimental Biology
Volume223
Issue number4
ISSN0022-0949
DOIs
Publication statusPublished - Feb 2020

Keywords

  • Air-breathing fish
  • Gas exchange partitioning
  • PH regulation

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