Selectively bred oysters can alter their biomineralization pathways, promoting resilience to environmental acidification

Abstract

Commercial shellfish aquaculture is vulnerable to the impacts of ocean acidification driven by increasing carbon dioxide (CO2) absorption by the ocean as well as to coastal acidification driven by land run off and rising sea level. These drivers of environmental acidification have deleterious effects on biomineralization. We investigated shell biomineralization of selectively bred and wild‐type families of the Sydney rock oyster Saccostrea glomerata in a study of oysters being farmed in estuaries at aquaculture leases differing in environmental acidification. The contrasting estuarine pH regimes enabled us to determine the mechanisms of shell growth and the vulnerability of this species to contemporary environmental acidification. Determination of the source of carbon, the mechanism of carbon uptake and use of carbon in biomineral formation are key to understanding the vulnerability of shellfish aquaculture to contemporary and future environmental acidification. We, therefore, characterized the crystallography and carbon uptake in the shells of S. glomerata, resident in habitats subjected to coastal acidification, using high‐resolution electron backscatter diffraction and carbon isotope analyses (as δ13C). We show that oyster families selectively bred for fast growth and families selected for disease resistance can alter their mechanisms of calcite crystal biomineralization, promoting resilience to acidification. The responses of S. glomerata to acidification in their estuarine habitat provide key insights into mechanisms of mollusc shell growth under future climate change conditions. Importantly, we show that selective breeding in oysters is likely to be an important global mitigation strategy for sustainable shellfish aquaculture to withstand future climate‐driven change to habitat acidification.

Evolved differences in energy metabolism and growth dictate the impacts of ocean acidification on abalone aquaculture

“…We also demonstrate such variation in abalone, with trait divergence indicated at the scale of populations within a single species. Our evidence suggests that in the case of abalone, traits enabling rapid growth show a negative correlation with traits needed for OA resistance during early development, in contrast to findings from commercially selected oysters in Australia ( 17 ). While it is unknown as to whether this relationship may hold true for other wild upwelling/nonupwelling populations, by selecting for rapid growers, aquaculture operators may inadvertently be selecting for genotypes vulnerable to OA.…”

“…Significant uncertainty remains regarding how these sensitivities will affect shellfish production, especially since commercially cultured taxa show different vulnerabilities to OA ( 15 ). Variation in responses to OA is likely a complex function of differences in natural selection regimes ( 15 – 17 ), sensitivities among different early-life history stages ( 18 ), and in the nature and strength of transgenerational effects ( 19 ). As such, there is a critical need to understand how, and in which contexts, these factors contribute to OA impacts on molluscan seed production.…”

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

“…As shown for S. glomerata , production of commercial bivalves that are more resilient to global change stressors, in tandem with advances from selective breeding efforts, hold promise in designing strategies for evolutionary rescue of key aquaculture resources to help climate proof shellfish industries. A better understanding of calcification physiology and mechanisms is needed, as recent studies show that this process is phenotypically plastic and can be adjusted with respect to environmental conditions (Fitzer et al, , , ; Zhao, Zhang, et al, ).…”

The impact of environmental acidification on the microstructure and mechanical integrity of marine invertebrate skeletons

“…An SEM-EBSD investigation of Mytilus galloprovincialis transplanted to a CO 2 vent (~pH = 7.2–7.8) revealed that they grew a thinner shell with disordered crystallography (Rodolfo-Metalpa et al ., 2011; Hahn et al ., 2012). This was also the case the shells of the oysters Magallana angulata (pH 7.2, 7.5) and M. hongkongensis (pH 7.3) grown in laboratory (CO 2 dosing) (Meng et al ., 2018, 2019), and Saccostrea glomerata farmed in coastal acidified environments (pH 7.6–7.8) (Fitzer et al ., 2018, 2019b). The disordered crystallography in S. glomerata wild type oysters grown in coastal acidified environments was as a result of altered biomineralisation pathways shown by changing shell carbon isotopes (Fitzer et al, 2019b).…”