Bleaching resistant corals retain heat tolerance following acclimatization to environmentally distinct reefs

Abstract

Urgent action is needed to prevent the demise of coral reefs as the climate crisis leads to an increasingly warmer and more acidic ocean. Propagating climate change resistant corals to restore degraded reefs is one promising strategy; however, empirical evidence is needed to determine if resistance is retained following transplantation within or beyond a coral’s natal reef. Here we assessed the performance of bleaching-resistant individuals of two coral species following reciprocal transplantation between environmentally distinct reefs (low vs high diel variability) to determine if stress resistance is retained following transplantation. Critically, transplantation to either environment had no influence on coral bleaching resistance, indicating that this trait was relatively fixed and is thus a useful metric for selecting corals for reef restoration within their native range. In contrast, growth was highly plastic, and native performance was not predictive of performance in the novel environment. Coral metabolism was also plastic, with cross transplants of both species matching the performance of native corals at both reefs within three months. Coral physiology (autotrophy, heterotrophy, and metabolism) and overall fitness (survival, growth, and reproduction) were higher at the reef with higher flow and fluctuations in diel pH and dissolved oxygen, and did not differ between native corals and cross-transplants. Conversely, cross-transplants at the low-variability reef had higher fitness than native corals, thus increasing overall fitness of the recipient population. This experiment was conducted during a non-bleaching year, which suggests that introduction of these bleaching-resistant individuals will provide even greater fitness benefits to recipient populations during bleaching years. In summary, this study demonstrates that propagating and transplanting bleaching-resistant corals can elevate the resistance of coral populations to ocean warming while simultaneously maintaining reef function as the climate crisis worsens.

Marine heatwaves depress metabolic activity and impair cellular acid–base homeostasis in reef‐building corals regardless of bleaching susceptibility

“…This study was conducted at a coral‐dominated patch reef (PR) in the outer lagoon (PR13; 21.4515°N, 157.7966°W), where the most abundant reef‐building corals were M. capitata and P. compressa . This region of Kāne'ohe Bay is characterized by relatively short seawater residence times (<24 h; Lowe et al, 2009) and diel pH ranges twofold to threefold higher than other regions of the bay with longer residence times (Barott, Huffmyer, et al, 2020; Page et al, 2018). Hourly sea surface temperatures on the reef from the 2015 and 2019 heatwaves were obtained from the NOAA temperature sensor on Moku o Lo'e in Kāne'ohe Bay (Station ID: 1612480).…”

Marine heatwaves depress metabolic activity and impair cellular acid-base homeostasis in reef-building corals regardless of bleaching susceptibility

“…Acid-base homeostasis is energetically expensive, and the costs of this vital maintenance process increase following stress, and so may be particularly exacerbated during coral bleaching. There is a growing understanding of coral acid-base sensing mechanisms (Barott, Barron, and Tresguerres 2017; Barott, Venn, et al 2020) and the downstream effectors involved in maintaining acid-base homeostasis in the cytosol (Laurent et al 2014), calcifying fluid (Zoccola et al 2015; Barott, Perez, et al 2015; Zoccola et al 2004), and symbiosome (Barott, Venn, et al 2015; Bertucci et al 2009; Barott, Perez, et al 2015). While previous work in corals has shown corals can upregulate active acid-base regulation processes under ambient temperature conditions, the relative contribution of passive (e.g.…”

“…This study was conducted at a coral-dominated patch reef (PR) in the outer lagoon (PR13; 21.4515°N, 157.7966°W), where the most abundant reef-building corals were Montipora capitata and Porites compressa . This region of Kāne’ohe Bay is characterized by relatively short seawater residence times (<24 hours, Lowe et al 2009) and diel pH ranges 2 – 3 fold higher than other regions of the bay with longer residence times (Barott, Huffmyer, et al 2020; Page et al 2018). Hourly sea surface temperatures on the reef from the 2015 and 2019 heatwaves were obtained from the NOAA temperature sensor on Moku o Lo’e in Kāne’ohe Bay (Station ID: 1612480).…”

“…However, little is known about how climate change affects acid-base homeostasis in corals. The potential effects of heat stress on acid-base regulation pose a particular challenge for maintaining coral calcification, as biomineralization is highly pH-dependent (Barott, Venn, et al 2020; Venn et al 2011; McCulloch et al 2012). Indeed, recent studies have found that temperature stress alters the pH of the external calcifying fluid and depresses calcification (Schoepf et al 2021; Guillermic et al 2021), highlighting the need to better understand the physiology of coral climate change responses across biological scales.…”

Selecting Heat-Tolerant Corals for Proactive Reef Restoration

“…The targeted selection of corals using any of these techniques should be expected to come with trade-offs because there Palumbi et al, 2014;Howells et al, 2016;Kenkel and Matz, 2016;Jury and Toonen, 2019;Schoepf et al, 2019;Quigley et al, 2020b;Voolstra et al, 2020 Known performance Observed past performance of a colony is predictive of future performance Need pre-established individuals monitored over time Reliable, in situ, inexpensive, can be integrated into nursery propagation Drury et al, 2017a;Fisch et al, 2019;Barott et al, 2020*;Matsuda et al, 2020;Ritson-Williams and Gates, 2020;Drury and Lirman, 2021 Stress tests A sample representing the source colony undergoes heat stress, which is predictive of future performance Not fully representative of natural performance, ex situ, requires aquaria infrastructure, limited scalability Fast, reproducible, inexpensive once established Barshis et al, 2013;Palumbi et al, 2014;Thomas et al, 2018;Morikawa and Palumbi, 2019;Voolstra et al, 2020 Host genetics Using adaptive variants, epigenetics, or gene expression profiles to predict performance Requires molecular work, expensive, high technical dependencies, unlikely to be single large-effect genes, may be species-specific Mechanistic, targeted (within species), scalable, reproducible Bay and Palumbi, 2014;Dixon et al, 2015;Rose et al, 2015;Kirk et al, 2018;Fuller et al, 2020;Quigley et al, 2020a;Drury and Lirman, 2021 Algal symbiosis Algal symbiont communities influence holobiont performance…”