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

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 pCO 2 /low pH seawater with reduced aragonite saturation state (Ω 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 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) pCO 2 seawater from fertilization through final metamorphosis to juvenile 'spat.' In each year, high pCO 2 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 pCO 2 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 pCO 2 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 pCO 2 seawater.

Limitations of cross‐ and multigenerational plasticity for marine invertebrates faced with global climate change

“…Due to their ability to maintain shell structure, change metabolic rate and with plasticity in carbon source for shell building, they are also better able to calcify in estuarine regions naturally low in pH and CaCO 3 saturation (Fitzer et al, 2018(Fitzer et al, , 2019Parker et al, 2012). Larvae produced through selection of Crassostrea gigas also had better growth and settlement under pH T 7.5 than wild-type larvae (Durland, Waldbusser, & Langdon, 2019).…”

Temporally balanced selection during development of larval Pacific oysters (Crassostrea gigas) inherently preserves genetic diversity within offspring

“…Comprehensive details regarding all culture methods (broodstock conditioning, cross design, larval culture and sampling) can be found in our previous related study [ 23 ] but these will be briefly reviewed here.…”

“…Units were filled with hatchery seawater (25°C, salinity of 32, 10 μm-filtered) that had been aerated overnight to equilibrate dissolved p CO 2 to ambient levels (approx. 400 µatm CO 2 , pH = 7.9–8.1, Ω arag = 2.3–2.7 [ 23 ]). The pH, temperature and dissolved oxygen of individual culture chambers were monitored daily and no substantial aberrations in water quality were observed [ 23 ].…”

Selection Experiments in the Sea: What Can Experimental Evolution Tell Us About How Marine Life Will Respond to Climate Change?

“…For example, in some managed populations, further selection may not be required. Traits that are favored in captive breeding settings, such as fast growth and disease resistance, have been correlated with increased resistance to ecologically relevant stressors, such as ocean acidification resistance in oysters (Durland et al, 2019;Fitzer et al, 2019). However, in other systems, rapid growth has been negatively associated with fitness in acidified conditions, as in red abalone (Swezey et al, 2020), so that ecological resiliency runs antagonistic to traits that increase production yield.…”