Within- and transgenerational plasticity of a temperate salmonid in response to thermal acclimation and acute temperature stress

Abstract

Environmental temperatures associated with climate change are rising too rapidly for many species to adapt, threatening the persistence of taxa with limited capacities for thermal acclimation. We investigated the capacity for within- and transgenerational responses to increasing environmental temperatures in brook trout (Salvelinus fontinalis), a cold-adapted salmonid. Adult fish were acclimated to temperatures within (10□) and above (21□) their thermal optimum for six months before spawning, then mated in a full factorial breeding design to produce offspring from cold- and warm-acclimated parents as well as bidirectional crosses between parents from both temperature treatments. Offspring families were subdivided and reared at two acclimation temperatures (15□ and 19□) representing their current environment and a projected climate change scenario. Offspring thermal physiology was measured as the rate of oxygen consumption (MO2) during an acute change in temperature (+2□ h-1) to observe their MO2-temperature relationship. We also recorded resting MO2, the highest achieved (peak) MO2, and critical thermal maximum (CTM) as performance metrics. Within-generation plasticity was greater than transgenerational plasticity, with offspring acclimation temperature having demonstrable effects on peak MO2 and CTM. Transgenerational plasticity was evident as an elevated resting MO2 and the MO2-temperature relationship in offspring from warm-acclimated parents. Both parents contributed to offspring thermal responses, although the paternal effect was stronger. Although brook trout exhibit both within- and transgenerational plasticity for thermal physiology, it is unlikely that these will be sufficient for coping with long-term changes to environmental temperatures resulting from climate change.SummaryBrook trout (Salvelinus fontinalis) exhibit within-generation and transgenerational plasticity for thermal performance, although neither response appears sufficient to cope with long-term climate change effects.

Effects of generations in captivity and elevated rearing temperature on Ontario hatchery brook trout (Salvelinus fontinalis) fry quality and survival

“…Despite this reduction, increased rearing temperatures are often used to increase speed of development and manipulate the timing of fish production (D. J. Fraser et al, 2019; Marten, 1992), induce triploidy and sterilize fish for release (Galbreath & Samples, 2000), and to prepare individuals for post release environments with elevated water temperatures (Cook, Wilson, et al, 2018; Durtsche et al, 2021; Penney et al, 2021; Warriner et al, 2020). It is thought that elevated temperatures drive eggs to hatch in an underdeveloped state, due to accelerated activity and development of the hatch gland, compared to fish reared on temperatures that are cooler and closer to optimal (Hayes et al, 1953); and could be one cause of increased mortality, particularly at the hatched stage as found in our study.…”

Effects of generations in captivity and elevated rearing temperature on Ontario hatchery brook trout (Salvelinus fontinalis) fry quality and survival

“…Despite this reduction, increased rearing temperatures are often used to increase speed of development and manipulate the timing of fish production (D. J. Fraser et al, 2019;Marten, 1992), induce triploidy and sterilize fish for release (Galbreath & Samples, 2000), and to prepare individuals for post release environments with elevated water temperatures Durtsche et al, 2021;Penney et al, 2021;Warriner et al, 2020). It is thought that elevated temperatures drive eggs to hatch in an underdeveloped state, due to accelerated activity and development of the hatch gland, compared to fish reared on temperatures that are cooler and closer to optimal (Hayes et al, 1953); and could be one cause of increased mortality, particularly at the hatched stage as found in our study.…”