Carry-over effects of temperature and pCO2 in multiple Olympia oyster populations

Impacts of adult exposure to elevated temperature and altered carbonate chemistry on reproduction and offspring viability were examined in the Olympia oyster (Ostrea lurida). Three distinct populations of adult, hatchery-reared O. lurida, plus an additional cohort spawned from one of the populations, were sequentially exposed to elevated temperature (+4C, at 10C) and elevated pCO2 (+2204 μatm, at 3045 μatm) during winter months. Oysters were then induced to spawn volitionally in common conditions at ambient pCO2. Elevated winter temperature and pCO2 impacted male gonad development separately, and the two treatments acted antagonistically such that gonad stage and sex did not differ from control oysters. Male gametes were more developed after elevated temperature exposure, and less developed after high pCO2 exposure, but there was no impact on female gametes or sex ratios. Larval release occurred earlier in warm-exposed oysters, and tended to be later in high pCO2-exposed oysters. Fecundity over a 60 day collection period (in ambient conditions) was unaffected by pCO2 exposure, but winter warming conditions increased larval production. No effects on larval survival were detected in this study, but juveniles of parents exposed to elevated pCO2 had higher survival rates in the natural environment in two of the four deployment bays. These results indicate that despite impacts on gametogenesis and larval release timing, Olympia oyster fecundity in hatchery conditions is unaffected by winter warming and high pCO2, there are no significant negative effects on the offspring, and in certain environmental conditions carryover effects can be beneficial. Furthermore, persistent population-specific traits emphasize the importance of using multiple sources of test organisms in stress-response studies.