Effects of repeated daily acute heat challenge on the growth and metabolism of a cold-water stenothermal fish [RESEARCH ARTICLE]

Matthew M. Guzzo, Neil J. Mochnacz, Travis Durhack, Benjamin C. Kissinger, Shaun S. Killen, and Jason R. Treberg Temperature is an important environmental factor influencing fish physiology that varies both spatially and temporally in ecosystems. In small north-temperate lakes, cold water piscivores rely on nearshore prey; however, this region exceeds the optimal temperature of the foraging species during summer. To cope, piscivores make short excursions into the nearshore to feed and return to cold water to digest, but the physiological impacts of these repeated acute exposures to warm water are not well understood. We exposed juvenile lake trout (Salvelinus namaycush) to treatments where they were held at 10°C and exposed to either 17 or 22°C for 5 - 10 min daily for 53 days mimicking warm-water forays. Control fish, held at an average temperature of 10°C but not exposed to thermal variation, consumed more food and grew slightly faster than heat challenged fish, with no clear differences in body condition, hepatosomatic index, ventricle mass, or muscle concentrations of lactate dehydrogenase and cytochrome c oxidase. Aerobic metabolic rates measured at 10°C indicated that standard metabolic rates (SMR) were similar among treatments; however, fish that were repeatedly exposed to 17°C had higher maximum metabolic rates (MMR) and aerobic scopes (AS) than control fish and those repeatedly exposed to 22°C. There were no differences in MMR or AS between fi...
Source: Journal of Experimental Biology - Category: Biology Authors: Tags: RESEARCH ARTICLE Source Type: research