39. Adaptive capacity of the sea urchin Heliocidaris erythrogramma to ocean change: responses from fertilisation to the juvenile

Shawna A. Foo (1), Symon A. Dworjanyn (2), Alistair Poore (3), Januar Harianto (1), Maria Byrne (4)*

1 School of Medical Sciences, The University of Sydney, Sydney, New South Wales, Australia
2 National Marine Science Centre, Southern Cross University, Coffs Harbour, New South Wales, Australia
3 Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales, Australia
4 Schools of Medical and Biological Sciences, The University of Sydney, Sydney, New South Wales, Australia

Background
To accurately 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 the potential of species for genetic adaptation.

Methods
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 (-0.3-0.5 pH units) were investigated for fertilisation, larval success and juvenile metamorphosis.

Findings
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 pH. Larval development was compromised in low pH, but not temperature. By the settled juvenile stage, no impact of warming or acidification was evident and this was likely due to selective mortality of sensitive individuals. Across all environments tested, the juveniles exhibited a similar ability to calcify.

Conclusions
The impact of warming and acidification on development after fertilisation was influenced by parental identity, with the offspring of some dam-sire 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 at one stage could not predict the performance later in development and shows the importance of assessing impacts of ocean change across the life cycle of marine invertebrates.