| Summary: | 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 (Ωarag), 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 2 replicated experiments, in 2015 and 2016, using larvae from naturalized ‘wild’ and selectively bred stocks of the Pacific oyster Crassostrea gigas from the US Pacific Northwest 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 were variable between years, with no effect of seawater pCO₂ in the first 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 (+ 5 and 23%) 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.
|
|---|