Adaptive capacity of the sea urchin Heliocidaris erythrogramma to ocean change stressors: responses from gamete performance to the juvenile

To predict impacts of ocean acidification and warming on the responses of marine populations, it is important to determine an organism’s capacity for phenotypic plasticity and genetic adaptation. We determined the effects of near-future acidification and warming across the life cycle of Heliocidaris erythrogramma from fertilisation to metamorphosis in the progeny of 16 sire-dam crosses. Sources of variation in tolerance to warming (+3°C) and acidification (-0.3 to –0.5 pH units) were investigated for fertilisation, larvae and juveniles. Across all life stages, maternal legacy was important, with dam identity significantly interacting with stressors. Across the genotypes tested, fertilisation was negatively affected by increased temperature, but not low pH. Larval development was compromised by low pH, but not increased temperature. By the juvenile stage, no impact of warming or acidification was evident, likely due to selective mortality of sensitive individuals, indicating the presence of a subset of resilient progeny. Across all treatments, the juveniles exhibited a similar ability to calcify. The impact of treatments on development was influenced by parental identity, with the offspring of some sire-dam pairs more sensitive than others. That the progeny of some sire-dam pairs showed high stress tolerance indicates the potential for selection of resistant genotypes and adaptation that could facilitate the persistence of H. erythrogramma populations. Performance of progeny was not consistent across development, with the impact of stressors differing depending on developmental stage. This shows the importance of assessing climatic change across multiple stages in the life cycle.