Comparison of larval development in domesticated and naturalized stocks of the Pacific oyster Crassostrea gigas exposed to high pCO2 conditions

Authors: DURLAND, EVAN - Oregon State University; WALDBUSSER, GEORGE - Oregon State University; LANGDON, CHRIS - Oregon State University

Submitted to: Marine Ecology Progress Series
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/31/2019
Publication Date: 7/4/2019
Citation: Durland, E., Waldbusser, G., Langdon, C. 2019. Comparison of larval development in domesticated and naturalized stocks of the Pacific oyster Crassostrea gigas exposed to high pCO2 conditions. Marine Ecology Progress Series. 621:107-125. https://doi.org/10.3354/meps12983.
DOI: https://doi.org/10.3354/meps12983

Interpretive Summary: Ocean acidification (OA) has had significant negative effects on oyster larvae and oyster populations along the US West Coast over the last decade. While the physiological stress experienced by oyster larvae has been well studied, and shellfish hatcheries have adapted by buffering seawater, less research has evaluated fitness traits across larval development stages and between discrete oyster populations. Results of replicated experiments with two pools of Pacific oyster (Crassostrea gigas) larvae; one from naturalized ‘wild’ stocks and a second from selectively bred lines of oysters revealed that acidic (high pCO2 , low pH , reduced aragonite saturation state ('arag)) seawater inhibited early larval development and affected the timing, but not the magnitude, of mortality during this stage. The effects of acidified seawater on metamorphosis of pediveligers to final “spat” stage was variable between years, but larvae from selectively bred oysters produced, on average, more (+ 55% and 37%) and larger (+ 8% and 24%) spat in ambient and acidic seawater, respectively. These findings highlight the variable and stage-specific sensitivity of larval oysters to acidified seawater and the potential influence that genetic factors and therefore selective breeding could have in determining larval performance.

Technical Abstract: Ocean acidification (OA) has had significant negative effects on oyster populations on the West Coast of North America over the past decade. Many studies have focused on the physiological challenges experienced by young oyster larvae in high pCO2/low pH seawater with reduced aragonite saturation state ('arag) which is characteristic of OA. Relatively few, by contrast, have evaluated these impacts upon fitness traits across multiple larval stages and between discrete oyster populations. In this study we conducted two replicated experiments, in 2015 and 2016, using larvae from naturalized ‘wild’ and selectively bred stocks of the Pacific oyster (Crassostrea gigas) from the Pacific Northwest USA and reared them in ambient (~400 µatm) or high (~1600 µatm) pCO2 seawater from fertilization through final metamorphosis to juvenile ‘spat’. In each year, high pCO2 seawater inhibited early larval development and affected the timing, but not the magnitude, of mortality during this stage. The effects of acidified seawater on metamorphosis of pediveligers to spat was variable between years, with no effect of seawater pCO2 in one experiment but a ~42% reduction in spat in the second. Despite this variability, larvae from selectively bred oysters produced, on average, more (+ 55% and 37%) and larger (+ 8% and 24%) spat in ambient and high pCO2 seawater, respectively. These findings highlight the variable and stage-specific sensitivity of larval oysters to acidified seawater and the influence that genetic factors have in determining the larval performance of C. gigas exposed to high pCO2 seawater.