Summary
Effects of ocean acidification in conjunction with temperature change warrants investigation as little is known about potential interactive effects of these parameters on Antarctic benthic species. Methods were developed to culture juvenile Abatus nimrodi under experimental pCO2 and temperature scenarios. This species is lecithotrophic, undergoing direct development from embryos to juveniles within the brood pouches of adult females over an extended period. Adult urchins were collected from subtidal habitats by divers off Davis Station (68E 77S) in February 2010. Juvenile urchins were extracted from the parental brood pouch and separated into early and late juvenile stages. Juveniles were maintained individually in vials within a flow through system into which CO2-enriched air was supplied in order to regulate pCO2 in the sea water at the target levels of 450 ± 2.5 (pH8.08 ± 0.02), +990 ± 30 (pH 7.8 ± 0.01), +1580 ± 34 (pH 7.64 ± 0.02) and at temperatures of -1.8°C and 0°C for 4 weeks. The pH /alkalinity of the waters off Davis varied considerably between depths. The pH of coastal surface waters was between 8.5 and 8.7 while the pH of water at depth where animals were collected was between 8.2 and 8.3. Preliminary results from this investigation show no difference between treatments despite significant increases in spine growth of all juvenile stages of A. nimrodi over the experimental period. This suggests an inherent capacity for tolerance of varying levels of pH and temperature in seawater in the absence of the protection afforded by the maternal brood pouch.