The effect of temperature on specific dynamic action of juvenile fall-run Chinook salmon, Oncorhynchus tshawytscha

Vanessa K Lo; Benjamin T Martin; Eric M Danner; Dennis E Cocherell; Joseph J Cech Jr; Nann A Fangue

doi:10.1093/conphys/coac067

The effect of temperature on specific dynamic action of juvenile fall-run Chinook salmon, Oncorhynchus tshawytscha

Conserv Physiol. 2022 Oct 27;10(1):coac067. doi: 10.1093/conphys/coac067. eCollection 2022.

Authors

Vanessa K Lo¹, Benjamin T Martin², Eric M Danner³, Dennis E Cocherell¹, Joseph J Cech Jr¹, Nann A Fangue¹

Affiliations

¹ Department of Wildlife, Fish and Conservation Biology, University of California Davis, Davis, 95616 CA, USA.
² Department of Theoretical and Computational Ecology, University of Amsterdam, 1098 XH Amsterdam, The Netherlands.
³ NOAA Southwest Fisheries Science Center, Santa Cruz, 95060 CA, USA.

Abstract

Juvenile fall-run Chinook salmon (Oncorhynchus tshawytscha) in the Sacramento-San Joaquin River Basin experience temporally and spatially heterogenous temperature regimes, between cool upper tributaries and the warm channelized Delta, during freshwater rearing and outmigration. Limited water resources necessitate human management of dam releases, allowing temperature modifications. The objective of this study was to examine the effect of temperature on specific dynamic action (SDA), or the metabolic cost associated with feeding and digestion, which is thought to represent a substantial portion of fish energy budgets. Measuring SDA with respect to absolute aerobic scope (AAS), estimated by the difference between maximum metabolic rate (MMR) and standard metabolic rate (SMR), provides a snapshot of its respective energy allocation. Fish were acclimated to 16°C, raised or lowered to each acute temperature (13°C, 16°C, 19°C, 22°C or 24°C), then fed a meal of commercial pellets weighing 2% of their wet mass. We detected a significant positive effect of temperature on SMR and MMR, but not on AAS. As expected, there was no significant effect of temperature on the total O₂ cost of digestion, but unlike other studies, we did not see a significant difference in duration, peak metabolic rate standardized to SMR, time to peak, percent of meal energy utilized, nor the ratio of peak O₂ consumption to SMR. Peak O₂ consumption represented 10.4-14.5% of AAS leaving a large amount of aerobic capacity available for other activities, and meal energy utilized for digestion ranged from 5.7% to 7.2%, leaving substantial remaining energy to potentially assimilate for growth. Our juvenile fall-run Chinook salmon exhibited thermal stability in their SDA response, which may play a role in maintaining homeostasis of digestive capability in a highly heterogeneous thermal environment where rapid growth is important for successful competition with conspecifics and for avoiding predation.

Keywords: Aerobic scope; cost of digestion; fish; metabolism.

Associated data

figshare/10.6084/m9.figshare.20422302