Exposure to warmer water and prenatal cortisol independently alter transcriptional plasticity during early development in Chinook salmon (Oncorhynchus tshawytscha)

Freshwater ecosystems are changing rapidly from ongoing human induced environmental change. Determining whether organisms have the adaptive capacity to respond to stressors and by which mechanisms remain a challenge. Within the Environmental-Match framework we experimentally manipulated a maternal signal of environmental stress to see if it primed gene transcription plasticity to allow developing Chinook salmon (Oncorhynchus tshawytscha) to respond to water temperatures expected from climate modeling. Our OpenArray® chip approach across four functional groups (growth, metabolism, immune, stress) revealed elevated temperatures induced a diversity of effects on gene transcriptional profiles at different early life stages for candidate genes at all levels of the hierarchical evaluation (complete gene sets, functional gene groups, individual gene transcriptional phenotypes). However, contrary to predictions, pre-natal cortisol did not alter these transcriptional effects further and did not rescue temperature-driven increases in mortality. Results suggest that while exposure to signals of maternal stress have the capacity to induce complex life stage- and system-specific responses, they may not further mitigate existing responses induced by elevated water temperatures in Chinook salmon (possibly other species).