Antarctic cushion star Odontaster validus larval performance is negatively impacted by long-term parental acclimation...

Cross-generational responses, when the parents' environment influences offspring performance, may contribute to species resilience to climate change in rapidly warming regions such as coastal Antarctica. Adult Antarctic sea stars Odontaster validus were conditioned in the laboratory to two temperature treatments (ambient, 0 °C and warming, +3 °C) for two years, and their gametes were used to generate larval offspring. The response of their larvae to five temperatures (0 °C, 1 °C, 2 °C, 3 °C, and 4 °C) was examined over 145 days. Adults conditioned to 3 °C produced significantly smaller eggs compared with those from 0 °C conditioned adults. After fertilisation, larval size, development, and survival were comparable in offspring from 0 °C and 3 °C conditioned parents. After 34 days of development, while survival was greater in offspring from 3 °C adults, offspring size was reduced during the transition from the gastrula to the bipinnaria larva. After ~50 days, survival in larvae from 3 °C conditioned adults decreased, and larval development was arrested at the bipinnaria stage (the exception being for larva reared at 4 °C which reached the early-brachiolaria). By the end of the experiment (145 days), offspring of the 0 °C conditioned adults had greater survival (17.6-34.3 %) and growth (final size = 697 to 773 μm) and had reached the early-brachiolaria larval stage, compared to those from the 3 °C conditioned adults (survival 7.0-19.3 %; growth final size = 380 to 624 μm) with early-brachiolaria larval stages mostly absent. Long-term acclimation of adults in elevated temperatures projected for the end of the century did not result in positive carryover outcomes for offspring, and did not lead to offspring being better suited to elevated temperatures. While O. validus adults may survive exposure to projected warming and produce viable gametes, their larval offspring may have lower developmental success. The downstream effects of poor recruitment of a key species such as O. validus would have important outcomes for coastal Antarctic ecosystems.