The emergence emergency: a mudskipper's response to temperatures

This study examined the relationship between prolonged (5 weeks) exposure to a range of temperatures (22, 25, 28, or 32 °C) on oxygen uptake rate and movement behaviours (i.e., thermoregulation and emergence) in a common amphibious fish, the barred mudskipper (Periophthalmus argentilneatuis). At the highest temperature examined (32 °C, approximately 5 °C above their summer average temperatures), barred mudskippers exhibited 33.7 to 97.7% greater oxygen uptake rates at rest (ṀO2Rest), emerged at a higher temperature (CTe; i.e., a modified critical thermal maxima (CTMax) methodology) of 41.3±0.3 °C relative to those maintained at 28, 25, or 22 °C. The 32°C-maintained fish also ceased movement activity at the highest holding temperature suggesting that prolonged submergence at elevated temperatures is physiologically and energetically stressful to the individual. Using exhaustive exercise protocols with and without air exposure to simulate a predatory chase, the time to recovery was examined for all individuals. When submerged, mudskippers required 2.5x longer recovery time to return to resting oxygen uptake from exhaustive exercise than those fully emerged in air. Oxygen uptake data revealed that air exposure did not accrue oxygen debt, thereby allowing faster return to resting oxygen consumption rates. If the option to emerge was not available, mudskippers preferentially sought more benign water temperatures (26.7±2.1 °C), resembling th...
Source: Journal of Thermal Biology - Category: Biology Source Type: research