Effects of ocean acidification on the embryos and larvae of red king crab, Paralithodes camtschaticus

► We examined the effect of ocean acidification on red king crab embryos and larvae. ► Acidified water increased the size of embryos while decreasing yolk size. ► Hatch duration was increased under acidification but fecundity was unchanged. ► Larvae from acidified embryos were longer and had reduced survival. ► Calcium content was increased in both larvae and females in acidified water. The effects of the decline in ocean pH, known as ocean acidification, on marine species are not well understood. To test the effects on embryos and larvae of red king crab, Paralithodes camtschaticus, ovigerous crab and their larvae were held in CO2-acidified (pH 7.7) and control (ambient; pH 8.0) seawater during development. Morphometrics, hatch duration, fecundity, survival, mineral content, and condition were measured. Acidified embryos had 4% larger eyes and 5% smaller yolks, while mean hatch duration was 33% longer and female fecundity was unaffected. Acidified embryos also resulted in 4% longer larvae while acidified larvae had lower survival. Calcium content of both larvae and female carapaces after molting increased by 5% and 19%, respectively. Although ocean acidification may increase larval size and calcium content, the implications of this are unclear and decreased survival is likely to harm red king crab populations.