Growth and transgenerational acclimatization of juvenile Pocillopora damicornis

Abstract Global carbon emissions and associated increase in ocean temperatures are understood to be the main driving force in the degradation of coral reefs. Elevated temperatures impact various life stages of scleractinian corals, from the free-floating planulae of brooding corals to older, sexually viable individuals. With global warming, questions have arisen over whether organismal adaptation will be enough to keep up with the pace of environmental change. Researchers have pursued investigations of whether or not rapid acclimatization, through transgenerational plasticity, can help protect populations until genetic adaptation occurs. Acclimatization in corals has been widely studied in all life stages of corals, with the important exception of recently settled juveniles. In this study, I built upon past research by exposing adult Pocillopora damicornis colonies to elevated (28.5°C) or ambient (25.5°C) temperatures and examining the settlement ability and growth of their planulae ex situ . Juveniles from preconditioned parents fared better in higher temperatures compared to their naïve counterparts. Lunar timing of planula release between treatments peaked at different times in the lunar cycle. Peak planula release occurred on lunar day 23 for prestressed corals and on lunar day 7 for corals from ambient temperature seawaters. While future projects should follow up on these preliminary trials with in situ experiments to assess this phenomenon in the field, this study represents an important step in understanding how corals may be able to acclimatize and eventually adapt to climate change.