Effects of maternal oxidative stress and gametic cortisol exposure on Fraser River sockeye salmon (Oncorhynchus nerka) offspring

Abstract

Though intergenerational effects have been reported in a wide range of taxa including insects, plants, birds, and fish, little is known about the potential effects of oxidative stress and gametic cortisol exposure on future generations of fish. The semelparous, migratory life history of Pacific salmon (Oncorhynchus spp.) requires a delicate balance of resource allocation and thus provides a unique opportunity to explore intergenerational and intraspecific effects of oxidative stress. In Chapter 2, I assessed oxidative health in sockeye salmon (O. nerka) from three distinct populations in the Fraser River (British Columbia) and demonstrated that neither maternal antioxidant concentration nor oxidative stress is conferred to offspring and that oxidative stress appears to be related to population at specific offspring life stages. In Chapter 3, I assessed the effect of maternal oxidative health on egg cortisol levels, and the effect of egg cortisol on offspring oxidative health. I also experimentally elevated egg cortisol to mimic maternal stress, and found that there may be a buffering mechanism in the mother and the egg to avoid negative effects of hypercortisolism on oxidative health. Given the population level differences in productivity and abundance, population-specific information on oxidative stress in sockeye salmon (both as adults and offspring) can help identify which sockeye salmon stocks may be at greater risk of the resonating effects of oxidative stress on offspring.