ABSTRACT
The ontogenetic development in teleost fish is sensitive to temperature, and the developmental rate has a direct relationship with the environmental temperature within a species' thermal tolerance limit. Temperature determines time to and survival at hatching. Yellow perch is a North American species of ecological and commercial importance, and its phenology is vulnerable to climate change. The embryonic development of yellow perch was comparable to closely related members of the family Percidae. Developmental progression was fastest at 18°C and slowest at 12°C, with medial progression at 15°C. Time to hatch and swim-up, feeding onset, and exogenous feeding phases were different across all incubation temperatures regardless of a gradual post-hatch warming of the 12 and 15°C groups to a common garden temperature of 18°C. Incubation temperature may lower the rate of survival to hatch at 15°C and had complex impacts on developmental abnormalities. Temperature had significant effects on the development rate, time of hatch, survival, and incidence of developmental abnormalities. Early ontogenetic thermal history in ectotherms is an important factor determining phenotypic variation. It will be important to link the thermally induced changes in development described here to the physiological and morphological differences and to link the developmental abnormalities to functional performance.
ABSTRACT
Anthropogenic impacts can lead to increased temperatures in freshwater environments through thermal effluent and climate change. Thermal preference of aquatic organisms can be modulated by abiotic and biotic factors including environmental temperature. Whether increased temperature during embryogenesis can lead to long-term alterations in thermal preference has not been explicitly tested in native freshwater species. Lake (Coregonus clupeaformis) and round (Prosopium cylindraceum) whitefish were incubated at natural and elevated temperatures until hatching, following which, all groups were moved to common garden conditions (15°C) during the post-hatching stage. Temperature preference was determined at 8 months (Lake whitefish only) and 12 months of age (both species) using a shuttle box system. Round whitefish preferred a cooler temperature when incubated at 2 and 6°C compared with 0.5°C. Lake whitefish had similar temperature preferences regardless of age, weight and incubation temperature. These results reveal that temperature preference in freshwater fish can be programmed during early development, and that round whitefish may be more sensitive to incubation temperature. This study highlights the effects that small increases in temperature caused by anthropogenic impacts may have on cold-adapted freshwater fish.
