DOI: 10.5061/dryad.2rbnzs7j7
title: Exposure to exogenous egg cortisol does not rescue juvenile Chinook salmon body size, condition, or survival from the effects of elevated water temperatures

description: Climate change is leading to altered temperature regimes which are
 impacting aquatic life, particularly for ectothermic fish. The impacts of
 environmental stress can be translated across generations through
 maternally-derived glucocorticoids, leading to altered offspring
 phenotypes. Although these maternal stress effects are often considered
 negative, recent studies suggest this maternal stress signal may prepare
 offspring for a similarly stressful environment (environmental match). We
 applied the environmental match hypothesis to examine whether a prenatal
 stress signal can dampen the effects of elevated water temperatures on
 body size, condition, and survival during early development in Chinook
 salmon Oncorhynchus tshawytscha from Lake Ontario, Canada. We exposed
 fertilized eggs to prenatal exogenous egg cortisol (1000ng*mL-1 cortisol
 or 0ng*mL-1 control) and then reared these dosed groups at temperatures
 indicative of current (+0°C) and future (+3°C) temperature conditions.
 Offspring reared in elevated temperatures were smaller and had a lower
 survival at the hatchling developmental stage. Overall, we found that our
 exogenous cortisol dose did not dampen effects of elevated rearing
 temperatures (environmental match) on body size or early survival.
 Instead, our eyed stage survival indicates that our prenatal cortisol dose
 may be detrimental, as cortisol-dosed offspring raised in elevated
 temperatures had lower survival than cortisol-dosed and control reared in
 current temperatures. Our results suggest that a maternal stress signal
 may not be able to ameliorate the effects of thermal stress during early
 development. However, we highlight the importance of interpreting the
 fitness impacts of maternal stress within an environmentally relevant
 context.
description: <strong>Egg cortisol data</strong> shows the results
 from ELISA, including three replicates. Using dilution and egg mass, it
 was used to calculate the cortisol concentration per gram of egg.
 bcEggCortisol is the egg cortisol data transformed using Box-cox
 transformation (lambda=0.242), which was used for statistical
 tests. <strong>Fertilization
 success</strong> shows data used in the model (output after data
 went throught buildBinary function in the fullfact r package). Status
 indicates whether egg was fertilized (coded as 1) or unfertilized (coded
 as 0). Includes maternal identity, tray, cell ID which were used as random
 effects. Under cortisol treatment: Cortisol=1000ng/mL,
 Control=0ng/mL <strong>Early
 Survival</strong> shows data used in the model (output after data
 went throught buildBinary function in the fullfact r package). Status
 indicates whether individual was alive (coded as 1) or dead (coded as 0)
 at each development stage (fertilized, eyed, hatch, &
 fry). Includes maternal identity, tray, cell ID which were used as random
 effects. Under cortisol treatment: Cortisol=1000ng/mL,
 Control=0ng/mL <strong>Fry
 Morphology</strong> shows measurements of mass and ImageJ
 measurements. Each parameter was scaled prior to input into PCA, this
 scaled value is under 'parameter_scaled' (e.g.,
 'ForkedLength_scaled'). Scores for each rotated (Varimax) PCA
 component that had eigenvalues above 1 were included for each
 individual. Under cortisol treatment: Cortisol=1000ng/mL, Control=0ng/mL
 Individuals that had incomplete values (i.e., did not have all morphology
 characteristics) are not included in this
 dataset.