Antarctic emerald rockcod have the capacity to compensate for warming when uncoupled from CO₂‐acidification

Abstract

TitleAntarctic emerald rockcod have the capacity to compensate for warming when uncoupled from CO2 -acidification. P R I M A R Y R E S E A R C H A R T I C L EAntarctic emerald rockcod have the capacity to compensate for warming when uncoupled from CO 2 -acidification (Egginton & Campbell, 2016;Enzor et al., 2013Enzor et al., , 2017Franklin, Davison, & Seebacher, 2007;Jayasundara, Healy, & Somero, 2013;Seebacher et al., 2005); however, the degree of vulnerability and acclimation capacity may be species-specific (Egginton & Campbell, 2016;Franklin et al., 2007;Jayasundara et al., 2013; Robinson & Davison, 2008a,b;Seebacher et al., 2005). For example, studies of the emerald rockcod,Trematomus bernacchii, a dominant benthic species by biomass in the Ross Sea (Vacchi, La Mesa, & Greco, 2000), have demonstrated impacts of warming across several levels of organization, including limitations in cardiac performance (Jayasundara et al., 2013), sustained elevated metabolic costs (Enzor et al., 2013(Enzor et al., , 2017 & DeVries, 1967), and up to an 85% reduction in growth (Sandersfeld et al., 2015). In comparison, the bald notothen Pagothenia borchgrevinki has exhibited less sensitivity to warming, demonstrating partial compensation for increased metabolic rates (Enzor et al., 2013(Enzor et al., , 2017) and a greater capacity to cope marked by modifications in cardiorespiratory and metabolic adjustments (Franklin et al., 2007; Robinson & Davison, 2008a,b;Seebacher et al., 2005). Differential responses to warming may be explained by varied ecological niches of these species. Trematomus bernacchii are more benthic, ranging from shallow to deeper waters (50-400 m), compared to P. borchgrevinki that live just under the annual sea-ice potentially exposing them to more environmental variability and influencing a greater capacity to acclimate (Eastman, 1993). Although notothen species have showed varying responses to warming alone, the simultaneous addition of elevated CO 2 (i.e., multiple stressor) elicited more similar physiological responses (Enzor et al., 2013(Enzor et al., , 2017Strobel et al., 2012;Strobel, Graeve, et al., 2013;Strobel, Leo, et al., 2013). When exposed to elevated PCO 2 concurrently with warming, both species (Davis et al., 2016). Hyperventilation, while a sufficient buffering mechanism of hypercapnia in fishes, is also energetically expensive (Cameron & Cech, 1970;Dejours, 1981 Although understanding physiological sensitivity to acute and chronic exposures of CO 2 -acidification and elevated temperature is essential to predicting vulnerability to environmental change, often the first response of an organism to environmental change is to alter behavior (Nagelkerken & Munday, 2015). Biotic interactions are strongly driven by abiotic influences such that species may experience "trade-offs" between mounting stress tolerance mecha- The objectives of this study were (i) to examine how acclimation to increased temperature and PCO 2 impacted the physiological performance of juvenile emerald rockcod, T. bern...

Changes in Genome-Wide Methylation and Gene Expression in Response to Future pCO2 Extremes in the Antarctic Pteropod Limacina helicina antarctica

“…Future research concerning this ecologically critical species that aims to expand on our findings and past OA experiments will benefit from (i) executing long-term cultures of L. helicina antarctica under future pCO 2 extremes for at least 3-6 weeks and (ii) conducting integrated analyses of metabolic rate, calcification, gene expression, and epigenetic profiling. This 3-6 week range has proven to be a metabolic and transcriptional tipping point for other Antarctic ectotherms acclimating to increases in temperature and pCO 2 (Peck et al, 2010;Enzor and Place, 2014;Enzor et al, 2017;Davis et al, 2018). Quantifying DNA methylation at wholegenome or base-by-base levels across long-term acclimations will expand on dynamic epigenetic changes documented in this study and reveal whether or not they associate with or initiate plastic responses to global change.…”

“…Many Antarctic ectotherms have classically been considered to be specialized to an invariable environment, subsequently lacking phenotypic and physiological plasticity necessary for acclimatizing to environmental shifts on par with future climate change (Peck et al, 2004(Peck et al, , 2010(Peck et al, , 2014Beers and Jayasundara, 2015). A growing body of work is beginning to demonstrate, however, that physiological plasticity is retained and sufficient for metabolic recovery under a warmer and/or more acidic ocean in at least some Antarctic ectotherms (Seebacher et al, 2005;Peck et al, 2010;Enzor and Place, 2014;Reed and Thatje, 2015;Huth and Place, 2016a,b;Morley et al, 2016;Enzor et al, 2017;Davis et al, 2018;Hawkins et al, 2018). The responsiveness of DNA methylation in L. helicina antarctica to variation in pCO 2 may be linked to this species' environmental experience in situ.…”

Effects of ocean acidification on Antarctic marine organisms: A meta‐analysis

“…The effect of ocean acidification on Antarctic and Southern Ocean fish has been little studied, with only 8 studies and a total of 24 responses available for this meta‐analysis (Davis et al, 2018; Davis, Miller, Flynn, & Todgham, 2016; Enzor, Hunter, & Place, 2017; Enzor, Zippay, & Place, 2013; Flynn, Bjelde, Miller, & Todgham, 2015; Strobel et al, 2012; Strobel, Graeve, Poertner, & Mark, 2013; Strobel, Leo, Pörtner, & Mark, 2013). While not ideal, due to the lack of data, all the CO 2 treatment levels were combined and the results compared among biological responses, namely embryonic survival (development), cellular aerobic potential measured by citrate synthase enzyme activity in adults (CS), growth rate, heart rate, and oxygen (O 2 ) consumption rate (Figure 10).…”

You Better Repeat It: Complex CO2 × Temperature Effects in Atlantic Silverside Offspring Revealed by Serial Experimentation

“…For example, combined treatments synergistically decreased embryo survival in Antarctic dragon fish (Gymnodraco acuticeps) [48] and compromised temperature acclimation and aerobic performance in emerald rockcod (Trematomus bemacchii) [49]. As extreme stenotherms, polar species appear particularly vulnerable to combined climate effects [82], but eurythermal temperate species have demonstrated similar sensitivities.…”