Synthesis of Thresholds of Ocean Acidification Impacts on Echinoderms

Abstract

Assessing the vulnerability of marine invertebrates to ocean acidification (OA) requires an understanding of critical thresholds at which developmental, physiological, and behavioral traits are affected. To identify relevant thresholds for echinoderms, we undertook a three-step data synthesis, focused on California Current Ecosystem (CCE) species. First, literature characterizing echinoderm responses to OA was compiled, creating a dataset comprised of >12,000 datapoints from 41 studies. Analysis of this data set demonstrated responses related to physiology, behavior, growth and development, and increased mortality in the larval and adult stages to low pH exposure. Second, statistical analyses were conducted on selected pathways to identify OA thresholds specific to duration, taxa, and depth-related life stage. Exposure to reduced pH led to impaired responses across a range of physiology, behavior, growth and development, and mortality endpoints for both larval and adult stages. Third, through discussions and synthesis, the expert panel identified a set of eight duration-dependent, life stage, and habitat-dependent pH thresholds and assigned each a confidence score based on quantity and agreement of evidence. The thresholds for these effects ranged within pH from 7.20 to 7.74 and duration from 7 to 30 days, all of which were characterized with either medium or low confidence. These thresholds yielded a risk range from early warning to lethal impacts, providing the foundation for consistent interpretation of OA monitoring data or numerical ocean model simulations to support climate change marine vulnerability assessments and evaluation of ocean management strategies. As a demonstration, two echinoderm thresholds were applied to simulations of a CCE numerical model to visualize the effects of current state of pH conditions on potential habitat.

Revisiting tolerance to ocean acidification: Insights from a new framework combining physiological and molecular tipping points of Pacific oyster

“…Finally, tipping point is a single value that reflects susceptibility to stressors that is easily communicable to end-users and society (Bednaršek et al, 2019(Bednaršek et al, , 2021.…”

“…Tipping point is valid for a whole population regardless of habitat. In addition, this is a single, easily communicable value that reflects susceptibility to OA (Bednaršek et al, 2019(Bednaršek et al, , 2021. To date, only four studies have experimentally established reaction norms for marine calcifiers in relation to pH.…”

Tolerant Larvae and Sensitive Juveniles: Integrating Metabolomics and Whole-Organism Responses to Define Life-Stage Specific Sensitivity to Ocean Acidification in the American Lobster

“…While these studies have a great value in outlining the sensitivity of the American lobster to OA, improving our appreciation of the metabolic challenges that early life stages face under OA conditions requires: (i) investigating multiple successive early life stages, not excluding developmental keystones; (ii) determining early life stages responses to a discreet pH/pCO 2 gradient, instead of single or few specific OA scenarios, which enables us to produce more robust predictions of physiological responses and supports scienceinformed management decisions [43][44][45][46]; and (iii) explicitly investigating the metabolic implications of exposure to low pH/high pCO 2 [47]. Consequently, the aim of our work was to simultaneously investigate life history traits and metabolic (both at the cellular and whole-organism level) responses of successive early life stages exposed to a range of elevated pCO 2 conditions.…”

Upwelling‐level acidification and pH/pCO2 variability moderate effects of ocean acidification on brain gene expression in the temperate surfperch, Embiotoca jacksoni

“…This difference may represent an acidification threshold nearer to the 7.85 treatment, where the majority of transcriptional adaptation to acidification is activated. Such a threshold effect in gene expression patterns has also been observed in the gill tissue of spider crabs exposed to two levels of acidification (Harms et al, 2014), as well as in the muscle tissue of blue rockfish ( Sebastes mystinus ; Hamilton et al, 2017), and thresholds in OA response have been noted across taxa (Bednaršek et al, 2021; Castillo et al, 2014; Wittmann & Pörtner, 2013). Interestingly, although 33 gene sets were commonly enriched across the pH 7.85 and 7.70 static‐variable comparisons, the majority of them (30) were enriched in opposite directions depending on the pH level, with variability at pH 7.85 eliciting a directional response mirroring that of static acidification, and variability at pH 7.70 eliciting the opposite response (Figure 6; Table ).…”