Effects of Annual Thermal Regime on Growth Trajectories of Native Age-0 Brook Trout (Salvelinus fontinalis)

Abstract

The rapidly increasing temperatures of aquatic systems associated with climate change represent a novel threat to populations of brook trout (Salvelinus fontinalis), and much uncertainty remains about the potential of these populations to acclimate, adapt or compensate for such changes. The current study evaluated growth patterns of young-of-the-year brook trout in two tributaries with dramatically different annual thermal regimes. Using a common garden design, we evaluated the effect of variable incubation temperatures on embryo size, developmental phenology, yolk sac allocation, hatch timing and size at hatch under laboratory conditions. The results of the current study provide evidence for plasticity in the developmental response of brook trout to withstand moderate effects of climate change. The results of the field studies demonstrated wide variability among populations, individuals and cohorts. Laboratory studies suggested that population differences were largely mitigated by the effect of the environment and that incubation conditions appeared to have a strong moderating effect on population differences in early development.