Effects of elevated pCO2 and the effect of parent acclimation on development in the tropical Pacific sea urchin Echinometra mathaei

Abstract

Effects of acclimation to projected near-future ocean acidification (OA) conditions on physiology, reproduction and development were investigated in the tropical sea urchin Echinometra mathaei. Following 6 weeks in control or one of the three elevated pCO2 (pHNIST 7.5–8.1; pCO2 ~485–1,770 μatm) conditions, adult urchins exhibited a slight decline of growth in low pH treatments and moderately reduced respiration at intermediate levels. At 7 weeks, gametes from adults were used to produce larvae that were reared in their respective parental treatments. To assess whether larvae from acclimated parents are more resilient to elevated pCO2 than those not acclimated, larvae from control animals were also reared in the elevated pCO2 treatments. There was no difference in female ‘spawnability’ and oocyte size between treatments, but male spawning ability was reduced in increased pCO2 conditions. In elevated pCO2 treatments, the percentage of normal larvae and larval size decreased in the progeny of control- and elevated pCO2-acclimated parents, and arm asymmetry increased. Thus, acclimation of the parents did not make the progeny more resilient or sensitive to OA effects. Negative effects of increased pCO2 on reproduction and development may impact on recruitment and population maintenance of this species.