Abstract

Physiological mechanisms determining thermal limits in fishes are debated but remain elusive. It has been hypothesised that motor function loss, observed as loss of equilibrium during acute warming, is due to direct thermal effects on brain neuronal function. To test this, we mounted cooling plates on the heads of Atlantic cod (Gadus morhua) and quantified whether local brain cooling increased whole-organism acute upper thermal tolerance. Brain cooling reduced brain temperature by 2-6 degrees C below ambient water temperature and increased thermal tolerance by 0.5 and 0.6 degrees C on average relative to instrumented and uninstrumented controls, respectively, suggesting that direct thermal effects on brain neurons may contribute to setting upper thermal limits in fish. However, the improvement in thermal tolerance with brain cooling was small relative to the difference in brain temperature, demonstrating that other mechanisms (e.g. failure of spinal and peripheral neurons, or muscle) may also contribute to controlling acute thermal tolerance.

Keywords

Climate change; Fish; Global warming; Oxygen- and capacity-limited thermal tolerance; OCLTT; Critical thermal maximum; CTmax; Loss of equilibrium; LOE; Thermal ramping

Published in

Journal of Experimental Biology
2019, Volume: 222, number: 19, article number: jeb208249

UKÄ Subject classification

Fish and Wildlife Management


Publication identifier

DOI: https://doi.org/10.1242/jeb.208249

Permanent link to this page (URI)

https://res.slu.se/id/publ/102148