Effects of high pCO2 on snow crab larvae: Carryover effects from embryogenesis and oogenesis reduce direct effects on larval survival

Ocean acidification, a decrease in ocean pH with increasing anthropogenic CO2 concentrations, is expected to affect many marine animals. We determined the effects of ocean acidification on the economically important snow crab, Chionoecetes opilio. By holding females in treatment pH for two brooding cycles and using the resulting larvae, we assessed carryover effects from oogenesis and embryogenesis. Ovigerous females were held at three pHs: ~8.1 (Ambient), 7.8, and 7.5. Larvae were exposed to the same pH treatments in a fully crossed experimental design. Starvation-survival, morphology, condition, and calcium/magnesium content were assessed for larvae. In the first year, starvation-survival of larvae reared at ambient pH but hatched from embryos reared at reduced pH was lowered; however, the negative effect was eliminated when the larvae were reared at reduced pH. In the second year, there was no direct effect of either embryo or larval pH treatment, but larvae reared as embryos at reduced pH survived longer if reared at reduced pH. Larvae hatched from embryos held at pH 7.5 had lower calcium content right after hatching, but the effect was transitory in the second year. There was no effect of larval treatment on calcium content or effect of embryo or larval treatment on magnesium content. Larval morphometrics were slightly altered, though effect sizes were small smaller in the second year. These results suggest both that larvae are highly tolerant of reduced pH, and that embryos are able to acclimate to low pH and this effect carries over to the larval stage.