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

Abstract

Ocean warming is causing global coral bleaching events to increase in frequency, resulting in widespread coral mortality and disrupting the function of coral reef ecosystems. However, even during mass bleaching events, many corals resist bleaching despite exposure to abnormally high temperatures. While the physiological effects of

Coral bleaching response is unaltered following acclimatization to reefs with distinct environmental conditions

“…Harnessing these natural advantages by propagating bleaching-resistant individuals is a promising approach to maintain reef function increasing the bleaching resistance of a population using native (i.e., endemic, local) coral stocks. Furthermore, relative bleaching resistance of M. capitata and P. compressa has persisted through multiple in situ bleaching events ( 54 , 55 ), indicating that bleaching resistance is retained and will likely continue during future heatwaves of similar magnitude. This, in combination with heat stress response being unaffected by both transplantation and acclimatization to a complex in situ environment, makes bleaching resistance a promising trait for selecting individuals to enhance resistance of coral populations to climate change.…”

Experimental Assessment of Vulnerability to Warming in Tropical Shallow-Water Marine Organisms

“…This may be linked to the negative carbon balance caused by higher respiratory carbon consumption relative to photosynthetic carbon assimilation (Scheufen et al, 2017;Hammer et al, 2018;Rasmusson et al, 2020;Costa et al, 2021), while photorespiratory activity, a competing process with carbon fixation, is known to be enhanced by increased temperature (Zhang et al, 2018;Hu et al, 2020). In addition, metabolic depression and energy allocation to certain defensive mechanisms (Bernardet et al, 2019;Marín-Guirao et al, 2019;Innis et al, 2021) may have long-term consequences on energetic balance and growth. Previous studies highlight that maintaining metabolic balance in coral holobionts (host, symbiotic algae, and associated microbes) is crucial under stress conditions (Levas et al, 2013).…”

“…Previous studies highlight that maintaining metabolic balance in coral holobionts (host, symbiotic algae, and associated microbes) is crucial under stress conditions (Levas et al, 2013). Undoubtedly, energy deficiency could be exacerbated during bleaching in corals (Innis et al, 2021), which was visible at 34.5 • C. As coral calcification is known to be tightly coupled with photosynthetic and carbon translocation rates (Tremblay et al, 2016), a decrease in integrated photosynthetic capacity (photodamage, chlorophyll content, and zooxanthellae density) is likely to be among the key drivers for a decline in growth rates in the two corals at this temperature.…”

“…While the biomarker suite adopted in the present study seems sufficient to elucidate the overall stress effects in the tested species, since it displayed a temperature-dependent response, all biomarkers are not specific to heat stress. Incorporations of biomarkers, such as heat shock proteins, energy metabolismsrelated makers, and certain regulatory molecules (van Oppen and Oakeshott, 2020;Danaraj et al, 2021;Innis et al, 2021), particularly those at the molecular level, will enhance the precision and resolution of the IBR index. However, the selection of suitable biomarkers relies on advanced knowledge of the cause-effect relationship between temperature and complex biological responses of given species and populations, which remains inadequate, particularly in the tropical Southeast Asian region (Guan et al, 2020;Nguyen et al, 2021).…”

Molecular Commerce on Coral Reefs: Using Metabolomics to Reveal Biochemical Exchanges Underlying Holobiont Biology and the Ecology of Coastal Ecosystems

“…Hermatypic corals colonized by two different species of Symbiodiniaceae exhibited similar metabolite profiles in both host and symbiont, illustrating the potential for more thermally robust strains to colonize diverse hosts without negatively impacting resource allocation (Matthews et al, 2020). A variety of tools employed to examine the metabolomes of thermally stressed corals have demonstrated significant differences between stressed and control corals (Sogin et al, 2016;Farag et al, 2018;Williams et al, 2021) and Symbiodiniaceae (Petrou et al, 2018;Lawson et al, 2019) while others have demonstrated changes in metabolite exchange between host and symbiont (Hillyer et al, 2017(Hillyer et al, , 2018 or phenotypic differences in whole tissue metabolomes (Roach et al, 2021) or symbiocyte acid-base homeostasis (Innis et al, 2021). In a recent review, Matthews et al (2018) posit that Bacteria-Symbiodiniaceae metabolomic interactions that regulate stability between host and algal symbionts are crucial for holobiont resilience to environmental stress, extending areas of investigation into more complex aspects of intra-holobiont metabolomics.…”