A Transcriptomic Analysis of Phenotypic Plasticity in Crassostrea virginica Larvae under Experimental Acidification

Abstract

Ocean acidification (OA) is a major threat to marine calcifiers, and little is known regarding acclimation to OA in bivalves. This study combined physiological assays with next-generation sequencing to assess the potential for recovery from and acclimation to OA in the eastern oyster (Crassostrea virginica) and identify molecular mechanisms associated with resilience. In a reciprocal transplant experiment, larvae transplanted from elevated pCO2 (~1400 ppm) to ambient pCO2 (~350 ppm) demonstrated significantly lower mortality and larger size post-transplant than oysters remaining under elevated pCO2 and had similar mortality compared to those remaining in ambient conditions. The recovery after transplantation to ambient conditions demonstrates the ability for larvae to rebound and suggests phenotypic plasticity and acclimation. Transcriptomic analysis supported this hypothesis as genes were differentially regulated under OA stress. Transcriptomic profiles of transplanted and non-transplanted larvae terminating in the same final pCO2 converged, further supporting the idea that acclimation underlies resilience. The functions of differentially expressed genes included cell differentiation, development, biomineralization, ion exchange, and immunity. Results suggest acclimation as a mode of resilience to OA. In addition, the identification of genes associated with resilience can serve as a valuable resource for the aquaculture industry, as these could enable marker-assisted selection of OA-resilient stocks.

Development of a nature-based solution for mitigation of Pacific oyster summer mortality: use of the intertidal zone to improve resilience to environmental stressors

“…The observed reductions in growth were likely a result of reduced feeding opportunities in the intertidal zone, but, importantly, could support higher survival during summer months as a result of associated delays in reproductive development and/or reduced spawning (Cotter et al, 2010;Huvet et al, 2010;Cowan et al, 2023). Moreover, it has been suggested that individuals demonstrating plasticity in order to tolerate a range of environmental conditions at the expense of normal physiological function and energetics, may show a rebound in growth and survival when under more optimal conditions (Barbosa et al, 2022). This could be the case in the present study, as growth discrepancies were no longer apparent by the end of Year 2 (i.e.…”

Life‐stage‐dependent effects of multiple flood‐associated stressors on a coastal foundational species

“…Our results also showed no effect of low pH due to elevated CO 2 on veliger shell growth, which is consistent with other studies, which have found that oyster larvae exposed after initial prodissoconch shell development (i.e., D stage) can grow and survive in high p CO 2 conditions and low calcium carbonate saturation states until the pediveliger stage (Ko et al, 2013; Lawlor & Arellano, 2020; Miller et al, 2020). Following the energetically demanding period of rapid larval shell development, veliger larvae may be able to compensate for negative pH effects through reallocation of metabolic energy (Barbosa et al, 2022; Pan et al, 2015). Yet, we observed an additive interaction between hypoxia and low salinity that completely inhibited veliger larval growth (Figure 2b).…”

Secretory and transcriptomic responses of mantle cells to low pH in the Pacific oyster (Crassostrea gigas)

“…Although the function of most -if not all -of these genes is unknown in mollusks, there are some upregulated DEGs encoding secreted proteins exhibiting similarity with genes that have been implicated in biomineralization in other species, for example, secretory protein CORS26 (Maeda et al, 2001), fibrillin-2 (Arteaga-Solis et al, 2011Mead et al, 2022), andhemicentin-1 (Ramos-Silva et al, 2013;Germer et al, 2015;Jackson et al, 2015). Indeed, hemicentin-1, a multimodular extracellular matrix protein that interacts with basement membrane proteins to confer tissue linkage (Zhang et al, 2022), has been reported as downregulated in C. virginica larvae exposed to low pH (Barbosa et al, 2022), but also as upregulated in C. gigas larvae and adults exposed to low pH (Timmins-Schiffman et al, 2014;Dineshram et al, 2021), as in this study as well. Furthermore, secreted proteins involved in protein binding, ion binding, response to stress, and cellular response to stimulus were upregulated in mantle tissues of oysters kept at 7.6 pH.…”