Within- and transgenerational stress legacy effects of ocean acidification on red abalone (Haliotis rufescens) growth and survival

Understanding the mechanisms by which individual organisms respond and populations adapt to global climate change is a critical challenge. The role of plasticity and acclimation, within and across generations, may be essential given the pace of change. We investigated plasticity across generations and life stages in response to ocean acidification (OA), which poses a growing threat to both wild populations and the sustainable aquaculture of shellfish. Most studies of OA on shellfish focus on acute effects, and less is known regarding the longer-term carryover effects that may manifest within or across generations. We assessed these longer-term effects in red abalone (Haliotis rufescens) using a multi-generational split-brood experiment. We spawned adults raised in ambient conditions to create offspring that we then exposed to high pCO₂ (1,180 μatm; simulating OA) or low pCO₂ (450 μatm; control or ambient conditions) during the first three months of life. We then allowed these animals to reach maturity in ambient common garden conditions for four years before returning the adults into high or low pCO₂ treatments for 11 months and measuring growth and reproductive potential. Early-life exposure to OA in the F1 generation decreased adult growth rate, even after 5 years, especially when abalone were re-exposed to OA as adults. Adult, but not early-life exposure, to OA negatively impacted fecundity. We then exposed the F2 offspring to high or low pCO₂ treatments for the first three months of life in a fully factorial, split-brood design. We found negative transgenerational effects of parental OA exposure on survival and growth of F2 offspring, in addition to significant direct effects of OA on F2 survival. These results show that the negative impacts of OA can last within and across generations, but that buffering against OA conditions at critical life-history windows can mitigate these effects.