Persistence of positive carryover effects in the oyster, Saccostrea glomerata, following transgenerational exposure to ocean acidification

Ocean acidification (OA) is predicted to have widespread implications for marine organisms, yet the capacity for species to acclimate or adapt over this century remains unknown. Recent transgenerational studies have shown that for some marine species, exposure of adults to OA can facilitate positive carryover effects to their larval and juvenile offspring that help them to survive in acidifying oceanic conditions. But whether these positive carryover effects can persist into adulthood or the next generation is unknown. Here we tested whether positive carryover effects found in larvae of the oyster, Saccostrea glomerata following transgenerational exposure to elevated CO₂, could persist into adulthood and whether subsequent transgenerational exposure of adults to elevated CO₂ would facilitate similar adaptive responses in the next generation of larvae and juveniles. Following our previous transgenerational exposure of parental adults and first generation (F1) larvae to ambient (385 μatm) and elevated (856 μatm) CO₂, newly settled F1 juveniles were transferred to the field at ambient CO₂ for 14 months, until they reached reproductive maturity. At this time, the F1 adults were returned to the laboratory and the previous transgenerational CO₂ exposure was repeated to produce F2 offspring. We found that the capacity of adults to regulate extracellular pH at elevated CO₂ was improved if they had a prior history of transgenerational exposure to elevated CO₂. In addition, subsequent transgenerational exposure of these adults led to an increase in the resilience of their larval and juvenile offspring. Offspring with a history of transgenerational exposure to elevated CO₂ had a lower percentage abnormality, faster development rate, faster shell growth and increased heart rate at elevated CO₂ compared with F2 offspring with no prior history of exposure to elevated CO₂. Our results suggest that positive carryover effects originating during parental and larval exposure will be important in mediating some of the impacts of OA for later life-history stages and generations.19 page(s