No abstract

6Predicting how populations will respond to ocean change across generations is critical to 7 effective conservation of marine species. One emerging factor is the influence of parental 8 exposures on offspring phenotype, known as intergenerational carryover effects. Parental 9 exposure may deliver beneficial or detrimental characteristics to offspring that can influence 10 larval recruitment patterns, thus shaping how populations and community structure respond to 11 ocean change. Impacts of adult exposure to elevated winter temperature and pCO2 on 12 reproduction and offspring viability were examined in the Olympia oyster (Ostrea lurida) using 13 three populations of adult, hatchery-reared O. lurida, plus an additional cohort spawned from one 14 of the populations. Oysters were sequentially exposed to elevated temperature (+4°C, at 10°C), 15 followed by elevated pCO2 (+2204 µatm, at 3045 µatm) during winter months. Male gametes 16 were more developed after elevated temperature exposure and less developed after high pCO2 17 exposure, but there was no impact on female gametes or sex ratios. Oysters previously exposed 18 to elevated winter temperature released larvae earlier, regardless of pCO2 exposure. Those 19 exposed to elevated winter temperature as a sole treatment released more larvae on a daily basis, 20 but when also exposed to high pCO2 there was no effect. These combined results indicate that 21 elevated winter temperature accelerates O. lurida spermatogenesis, resulting in earlier larval 22 release and increased production, with elevated pCO2 exposure negating effects of elevated 23 temperature. Altered recruitment patterns may therefore follow warmer winters due to 24 precocious spawning, but these effects may be masked by coincidental high pCO2. Offspring 25 were reared in common conditions for one year, then deployed for three months in four estuarine 26 bays with distinct environmental conditions. Offspring of parents exposed to elevated pCO2 had 27 Spencer et al. preprint September 2019 3 higher survival rates in two of the four bays. This carryover effect demonstrates that parental 28 conditions can have substantial ecologically relevant impacts that should be considered when 29 predicting impacts of environmental change. Furthermore, Olympia oysters may be more 30 resilient in certain environments when progenitors are pre-conditioned in stressful conditions. 31Combined with other recent studies, our work suggests that the Olympia may be more equipped 32 than other oysters for the challenge of a changing ocean. 33

Predicting how populations will respond to ocean change across generations is critical to effective conservation of marine species. One emerging factor is the influence of parental exposures on offspring phenotype, known as intergenerational carryover effects. Parental exposure may deliver beneficial or detrimental characteristics to offspring that can influence larval recruitment patterns, thus shaping how populations and community structure respond to ocean change. Impacts of adult exposure to elevated winter temperature and pCO2 on reproduction and offspring viability were examined in the Olympia oyster (Ostrea lurida) using three populations of adult, hatchery‐reared O. lurida, plus an additional cohort spawned from one of the populations. Oysters were sequentially exposed to elevated temperature (+4°C, at 10°C), followed by elevated pCO2 (+2,204 μatm, at 3,045 μatm) during winter months. Male gametes were more developed after elevated temperature exposure and less developed after high pCO2 exposure, but there was no impact on female gametes or sex ratios. Oysters previously exposed to elevated winter temperature released larvae earlier, regardless of pCO2 exposure. Those exposed to elevated winter temperature as a sole treatment released more larvae on a daily basis but, when also exposed to high pCO2, there was no effect. These combined results indicate that elevated winter temperature accelerates O. lurida spermatogenesis, resulting in earlier larval release and increased production, with elevated pCO2 exposure negating effects of elevated temperature. Altered recruitment patterns may therefore follow warmer winters due to precocious spawning, but these effects may be masked by coincidental high pCO2. Offspring were reared in common conditions for 1 yr, then deployed for 3 months in four estuarine bays with distinct environmental conditions. Offspring of parents exposed to elevated pCO2 had higher survival rates in two of the four bays. This carryover effect demonstrates that parental conditions can have substantial ecologically relevant impacts that should be considered when predicting impacts of environmental change. Furthermore, Olympia oysters may be more resilient in certain environments when progenitors are pre‐conditioned in stressful conditions. Combined with other recent studies, our work suggests that the Olympia may be more equipped than other oysters for the challenge of a changing ocean.

Humans are the dominant ecological and evolutionary force on the planet today, transforming habitats, polluting environments, changing climates, introducing new species, and causing other species to decline in number or go extinct. Th ese worrying anthropogenic impacts, collectively termed global change, are often viewed as a confounding factor to minimize in basic studies and a problem to resolve or quantify in applied studies. However, these ' accidental experiments ' also represent opportunities to gain fundamental insight into ecological and evolutionary processes, especially when they result in perturbations that are large or long in duration and diffi cult or unethical to impose experimentally. We demonstrate this by describing important fundamental insights already gained from studies which utilize global change factors as accidental experiments. In doing so, we highlight why accidental experiments are sometimes more likely to yield insights than traditional approaches. Next, we argue that emerging environmental problems can provide even more opportunities for scientifi c discovery in the future, and provide both examples and guidelines for moving forward. We recommend 1) a greater fl ow of information between basic and applied subfi elds of ecology and evolution to identify emerging opportunities; 2) considering the advantages of the ' accidental experiment ' approach relative to more traditional approaches; and 3) planning for the challenges inherent to uncontrolled accidental experiments. We emphasize that we do not view the accidental experiments provided by global change as replacements for scientifi c studies quantifying the magnitude of anthropogenic impacts or outlining strategies for mitigating impacts. Instead, we believe that accidental experiments are uniquely situated to provide insights into evolutionary and ecological processes that ultimately allow us to better predict and manage change on our human-dominated planet.