Coral bleaching resistance variation is linked to differential mortality and skeletal growth during recovery

Abstract

The prevalence of global coral bleaching has focused much attention on the possibility of interventions to increase heat resistance. However, if high heat resistance is linked to fitness tradeoffs that may disadvantage corals in other areas, then a more holistic view of heat resilience may be beneficial. In particular, overall resilience of a species to heat stress is likely to be the product of both resistance to heat and recovery from heat stress. Here, we investigate heat resistance and recovery among individual Acropora hyacinthus colonies in Palau. We divided corals into low, moderate, and high heat resistance categories based on the number of days (4–9) needed to reach significant pigmentation loss due to experimental heat stress. Afterward, we deployed corals back onto a reef in a common garden 6‐month recovery experiment that monitored chlorophyll a , mortality, and skeletal growth. Heat resistance was negatively correlated with mortality during early recovery (0–1 month) but not late recovery (4–6 months), and chlorophyll a concentration recovered in heat‐stressed corals by 1‐month postbleaching. However, moderate‐resistance corals had significantly greater skeletal growth than high‐resistance corals by 4 months of recovery. High‐ and low‐resistance corals on average did not exhibit skeletal growth within the observed recovery period. These data suggest complex tradeoffs may exist between coral heat resistance and recovery and highlight the importance of incorporating multiple aspects of resilience into future reef management programs.

Assessing Acute Thermal Assays as a Rapid Screening Tool for Coral Restoration

“…Some restoration nurseries contain hundreds of genotypes per species and these nursery populations are likely to contain a wide distribution of heat tolerant individuals 15 . Incorporating tolerant nursery corals into outplanting and assisted sexual breeding efforts has the potential to bolster the resilience of restored populations, as long as heat tolerance is durable and not maladaptive for disease resistance 16 , growth 17 (but see 4,[18][19][20] ), or other life history traits. If biological interventions using tolerant corals are not incorporated, then ecological buffering and long-term persistence cannot be ensured.…”

A decade of progress in marine evolutionary biology

“…Herein, these processes are addressed in diverse empirical model systems ranging from diatoms to mollusks and fish (Green et al, 2022 ; Le Moan et al, 2022 ; Sefbom et al, 2022 ; Zhang et al, 2022 ), as well as in silico in two theoretical modeling studies (Eriksson et al, 2022 ; Marshall & Connallon, 2022 ). The link between genotype and phenotype is also the focus of several empirical studies here (Gefaell et al, 2022 ; Stenger et al, 2022 ; Walker et al, 2022 ), as is the seascape genomics of a wide range of taxa (Delaval, Bendall, et al, 2022 ; Delaval, Frost, et al, 2022 ; Fitz et al, 2022 ; Lapègue et al, 2022 ; Matias et al, 2022 ; Palumbi et al, 2022 ; Pampoulie et al, 2022 ), which has important implications for management of marine resources. Finally, the breadth of phylogenetic diversity and evolutionary history in the oceans is the topic of several articles focusing on the larval development of gastropods (Korshunova et al, 2022 ; Sun et al, 2022 ) and the evolution of small RNAs in cnidarians (Li & Hui, 2022 ).…”

“…Common‐garden experiments are often used to evaluate the performance of individuals under future climate change. Walker et al ( 2022 ) experimentally investigated bleaching resistance and recovery among colonies of the coral Acropora hyacinthus in Palau, by measuring coral bleaching, mortality, and skeletal growth. They showed that, although heat resistance and mortality were overall negatively correlated, the skeletal growth of less heat‐resistant corals was significantly faster than in corals highly resistant to heat stress.…”

The Coral Bleaching Automated Stress System (CBASS): A low‐cost, portable system for standardized empirical assessments of coral thermal limits

“…These photos can have 20–40 corals in them and be uploaded to cloud‐based document storage, such as Google Drive™. We have assayed them with a five‐point visual bleaching score (None, Visible, Moderate, Severe, Total; Walker et al 2023), an approach that correlates well with more quantitative measures of bleaching (Cornwell et al 2021; Evensen et al 2022; Walker et al 2022) and is suitable for scoring by machine learning algorithms. Alternatively, red (R), green (G), and blue (B) pixel intensities from an RGB photograph can be extracted to infer loss of chlorphyll density as inferred from an increase in pixel intensity of the red channel (Voolstra et al 2020).…”