Early environmental effects on growth rate, muscle development, and swimming performance in larval and age-0 Lake Sturgeon, Acipenser fulvescens
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Date
2019-08-23
Authors
Brandt, Catherine
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Abstract
In fishes, differences in egg incubation, water temperature, and substrate can have a significant impact on phenotypic development. This is particularly relevant during the first year of life when growth rate peaks and influences an individual’s life history trajectory. In the present study, Lake Sturgeon, Acipenser fulvescens, were reared in different environments for approximately one year. In the first year, sturgeon were reared in 3 temperature regimes (with or without substrate) that mimicked hatchery conditions or river temperature profiles. In the second year, embryos were incubated in MacDonald jars or adhered to substrate and newly hatched larvae were reared in different thermal environments (16, 18 and 20°C) for two weeks during the first month post-hatch. All treatments were then transferred to a common garden set-up where tanks were fed by river water at ambient temperature and natural light cycles. Fish were deprived of food when water temperature reached 1.5°C, then food was re-introduced when water temperature exceeded 2°C, approximately 4.5 months later. Yolksac volumes, body length and mass were assessed during both years. In the first year, there were differences in yolk sac absorption between substrate treatments in the first two weeks post-hatch, and differences in larval length between temperature treatments following the overwintering. In the second year, red muscle fibre area and myonuclear counts were assessed and volitional downward swimming and forced escape responses were tested. Growth rate in the first three months of life was highest in the 20°C group of fish but converged in all treatments during winter. Growth rate in fish raised in warmer waters during early life once again exceeded cooler water treatments post-winter, suggesting growth phenotype was fixed in early life, showing little phenotypic plasticity, and was temperature dependent. Thus, increased growing temperature during early life history results in development of a fast-growing phenotype post the first winter. Overall, there was an absence of significant differences between results for muscle fibre area and myonuclear counts between incubation and temperature treatments and the presence of significant differences between time points indicating a strong evolutionary pressure to maintain plasticity in muscle structure and swimming performance.
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Keywords
Lake Sturgeon, Growth, Muscle, Swimming Performance, Escape Response, Fish, Biology