Summary
Simultaneous effects of ocean acidification and temperature change in Antarctic environments warrant investigation as little is known about the synergistic consequences of these factors on Antarctic benthic species. Juvenile Abatus ingens and Abatus shackletoni were incubated under experimental pCO2 and elevated temperature scenarios reflective of those predicted by the IPCC (2007). Direct development from embryos to juveniles occurs in these species without a pelagic larval phase and the developing young are lecithotrophic for an extended period. Adult urchins were collected near Davis Station during the Austral summer season (January-February 2011). Juveniles were extracted from the parental brood pouch and reared in flow-through experimental treatments for 4 weeks. CO2-enriched air was supplied to seawater in which pCO2 was regulated at the target levels of 448¡¾6.51 (pH 8.01¡¾0.005), 846¡¾6.58 (pH 7.83¡¾0.005) and 1371¡¾7.34 (pH 7.63¡¾0.007) ppm and seawater temperature was set at -1¡¾0.03¢ªC (Control) and 1¡¾0.32¢ªC. Preliminary results from this investigation showed significant increases in spine growth in juveniles of both A.ingens and A. shackletoni over the experimental period. However, juveniles reared in 1¢ªC significantly exhibited more incidences of epithelial separation in the spines compared to those reared in -1¢ªC. This suggests that, although there is an inherent capacity for tolerance of varying levels of pH in seawater in the absence of the protection afforded by the maternal brood pouch, these juveniles are still at risk from increasing temperatures.