Meeting Abstract

P2.28  Saturday, Jan. 5  Ocean acidification and thermal stress in a polar ectotherm�\”physiological responses of the larvae of Sterechinus neumayeri to a potential future ocean YU, P. C.*; KAPSENBERG, L.; HOFMANN, G. E.; University of California, Santa Barbara; University of California, Santa Barbara; University of California, Santa Barbara pyu@lifesci.ucsb.edu

Polar ectotherms of coastal Antarctica experience the most thermostable environment of all shallow marine environments, and they have evolved in these stable conditions for 22 million years. This cold seawater also is rich in dissolved CO₂, and as a result presents a challenge to calcifying invertebrate fauna for biomineralization; future atmospheric loads of CO₂ will intensify this effect, resulting in overall acidification and calcium carbonate undersaturation. We tested the developmental stability of invertebrate development to simultaneous warming and acidification stresses: larvae of Sterechinus neumayeri were raised at -0.6 (control) and +2 °C under present day carbonate conditions, and at two elevated pCO₂ levels (650 and 1050 μatm). Developmental schedules overall were unaffected by elevated pCO₂ at control temperatures, and were accelerated by elevated temperatures. Respiration rates at control temperatures were largely unaffected by elevated pCO₂. In thermal stress trials, tolerance of acute heat stress (1hr exposures) was surprisingly high (up to 20 °C), and unaffected by CO₂ treatment, with high recovery and survival at several early developmental stages. While it has been hypothesized that warming effects may counteract potential depressive effects of higher CO₂, the climate changes occurring in Antarctica may be decoupled between rates of warming and rates of seawater CO₂ increase in different regions of the continent. The undersaturation of calcium carbonate in Antarctica will likely occur sooner than large changes in temperature, and calcifying larvae in the Earth’s southernmost marine ecosystem may not experience metabolic tradeoffs in the same way as temperate or tropical species.