OA exposure effects on Pacific oysters

Effects of Early Exposure of Pacific Oysters to Ocean Acidification on Subsequent Performance

Washington Sea Grant research documented the effects on performance of later-life and transgenerational Pacific oysters due to early exposure to acidified waters, and assessed genetic factors for breeding acidification-tolerant lines.

Principal Investigator

Carolyn S. Friedman, University of Washington, School of Aquatic and Fishery Sciences

Co-Principal Investigators

Mark Camara, USDA/ARS Shellfish Genetics

Jonathan Davis, Taylor Shellfish Farms, Inc.

Benoit Eudeline, Taylor Shellfish Farms, Inc.

Brent Vadopalas, University of Washington, School of Aquatic and Fishery Sciences


Washington Sea Grant-funded researchers examined the effects of high dissolved-CO2 levels on adult oyster reproduction, gametes and larvae, and on survivors’ subsequent performance. They conditioned broodstock to various CO2 levels, reared larvae to 11 months, tallied the number of animals that were ripe, and inspected effects on maturation, fertilization, larval survival, metamorphosis and hatching, and juvenile performance at three field sites. They also genotyped larval samples.

Research Updates


Much research has explored the effects of ocean acidification (OA) on shellfish larvae, but little has examined carryover effects from parent to offspring or the performance of shellfish that survive larval exposure. Larval Pacific oysters often suffer high mortality when exposed to elevated levels of dissolved carbon dioxide, but survivors might show enhanced performance in later life. Identifying resilient strains and their distinguishing genetic factors would allow selective breeding for OA tolerance of this commercially important shellfish.


Researchers saw mortality at only one field site, following a thermal event. They observed a difference in oyster size based on larval CO2 conditioning. Larvae whose parents were conditioned to high levels and who were themselves raised in low levels had the highest yield and survival one week after settlement. Larvae conditioned to high levels whose parents were conditioned to low levels had the worst survival. Low-low and high-high treatments yielded intermediate survival rates. These early findings appeared to confirm that OA can have long-term impacts on survival, which can only be understood by studying the oysters’ full life history.