Chum salmon migrating upriver accommodate to environmental temperatures through metabolic compensation

Abstract

Ectotherms adjust their thermal performance to various thermal ranges by altering their metabolic rates. These metabolic adjustments involve plastic and/or genetic traits and pathways depend on speciesspecific ecological contexts. Chum salmon (Oncorhynchus keta) are ecologically unique among the Pacific salmonids as early-run and late-run populations are commonly observed in every part of their range. In the Sanriku coastal area, Japan, early-run adults experience high water temperatures (12-24°C) during their migration, compared with those of the late-run adults (4-15°C), suggesting that the two populations might have different thermal performance. Here, we found population-specific differences in the thermal sensitivities of metabolic rates [resting metabolic rate, RMR, and maximum (aerobic) metabolic rate, MMR] and critical temperature maxima. Using these parameters, we estimated thermal performance curves of absolute aerobic scope (AAS). The populations had different thermal performance curves of AAS, and in both populations high values of AAS were maintained throughout the range of ecologically relevant temperatures. However, the populations did not vary substantially in the peak (AAS at optimal temperature, T optAAS) or breadth (width of sub-optimal temperature range) of the performance curves. The AAS curve of early-run fish was shifted approximately 3°C higher than that of late-run fish. Furthermore, when the data for RMR and MMR were aligned to the thermal differences from T optAAS , it became clear that the populations did not differ in the temperature dependence of their metabolic traits. Our results indicate that chum salmon thermally accommodate through compensatory alterations in metabolic rates. Our results imply that metabolic plasticity and/or the effect of genetic variance on plasticity might play a pivotal role in their thermal accommodation.

Intraspecific variability in thermal tolerance: a case study with coastal cutthroat trout

“…Indeed, thermal performance has been shown to differ across salmon Oncorhynchus spp. populations of the same species ( Abe et al , 2019 ; Chen et al , 2013 ; Eliason et al , 2011 ; Eliason et al , 2013 ; Stitt et al , 2014 ; Whitney et al , 2016 ), often matching the typical environmental temperatures to which they have encountered over prolonged periods. For example, Eliason et al.…”

Temperature and Diet Acclimation Modify the Acute Thermal Performance of the Largest Extant Amphibian

“…Thermal compensation enables the maintenance of physiological rates across environmental conditions. This was frequently observed in animals facing mildly cold environments [ 23 , 45 , 46 ]. This biological phenomenon is believed to partly offset the reduced physiological performance under cold and thus allows better exploitation of the environment by maintaining physiological activities such as locomotion, feeding, and development at low temperatures [ 47 ].…”

Straightforward upriver migration to spawning sites by chum salmon Oncorhynchus keta homing to coastal short rivers in the Sanriku region

“…Chinook salmon return to their natal rivers during almost any month of the year (Healey, 1991). Moreover, the distance of upriver migration of chum salmon varies among populations (Abe et al ., 2019; Olsen et al ., 2008), even though it is relatively shorter compared with those of other Pacific salmons (Salo, 1991). The difference in timing of river entry is inevitably linked to differences in physiological status at river entry, such as maturation and salinity tolerance (Cooke et al ., 2006; Cooke et al ., 2008; Crossin et al ., 2007).…”