Proton gradients across the coral calcifying cell layer: Effects of light, ocean acidification and carbonate chemistry

Venn, Alexander A.; Tambutté, Éric; Comeau, Steeve; Tambutté, Sylvie

doi:10.3389/fmars.2022.973908

Cited by 12 publications

(5 citation statements)

References 77 publications

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“…Low pH at the coral surface likely alters H + gradients across tissue layers 95 , 96 . This leads to decreased pH within coral cells 89 , 97 , 98 , in the mesoglea above the calcifying cell layer 99 , and of the calcifying fluid 100 , which has been observed in P. verrucosa even when calcification remains stable under OA 101 . Therefore, our findings suggest that P. verrucosa may undergo large internal pH changes under OA with limited effects on growth, indicating an enhanced capacity for internal pH regulation.…”

Section: Discussionmentioning

confidence: 95%

“…However, given that P. cylindrica may maintain a constant pH of the calcifying fluid under OA 104 , acid–base regulation could potentially differ between these two species 97 . Knowledge of these mechanisms and of the pH gradients between tissue layers and extracellular compartments, however, remains limited in scleractinian corals 99 . Furthermore, although P. cylindrica does not increase tissue thickness under OA 102 , it has characteristically thicker tissues than P. verrucosa 105 , which could underlie a greater ability to counter internal pH changes.…”

Section: Discussionmentioning

confidence: 99%

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Effects of water flow and ocean acidification on oxygen and pH gradients in coral boundary layer

Martins,

Ziegler,

Schubert

et al. 2024

Sci Rep

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Reef-building corals live in highly hydrodynamic environments, where water flow largely controls the complex chemical microenvironments surrounding them—the concentration boundary layer (CBL). The CBL may be key to alleviate ocean acidification (OA) effects on coral colonies by partially isolating them. However, OA effects on coral CBL remain poorly understood, particularly under different flow velocities. Here, we investigated these effects on the reef-building corals Acropora cytherea, Pocillopora verrucosa, and Porites cylindrica. We preconditioned corals to a control (pH 8.0) and OA (pH 7.8) treatment for four months and tested how low flow (2 cm s−1) and moderate flow (6 cm s−1) affected O2 and H+ CBL traits (thickness, surface concentrations, and flux) inside a unidirectional-flow chamber. We found that CBL traits differed between species and flow velocities. Under OA, traits remained generally stable across flows, except surface pH. In all species, the H+ CBL was thin and led to lower surface pH. Still, low flow thickened H+ CBLs and increased light elevation of surface pH. In general, our findings reveal a weak to null OA modulation of the CBL. Moreover, the OA-buffering capacity by the H+ CBL may be limited in coral species, though low flow could enhance CBL sheltering.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Effects of water flow and ocean acidification on oxygen and pH gradients in coral boundary layer

Martins,

Ziegler,

Schubert

et al. 2024

Sci Rep

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“…Upcoming studies should explore the effects of the exposure duration (i.e., short vs. long‐term) to variable pH on coral biomineralization mechanisms, which already appear to differ between more stable and fluctuating environmental conditions of pH (Comeau et al, 2021 ). The different dynamics of symbiotic partners might greatly influence calcification processes via distinct translocation of photosynthates ultimately influencing mechanisms of internal pH regulation (Allen‐Waller & Barott, 2023 ; Cameron et al, 2022 ; Venn et al, 2022 ). The use of isotopic tools such as the boron pH proxy in the coral skeleton would help that way, via tracing and defining the inputs of specific symbiotic partners into biomineralization mechanisms.…”

Section: Discussionmentioning

confidence: 99%

“…symbiotic partners might greatly influence calcification processes via distinct translocation of photosynthates ultimately influencing mechanisms of internal pH regulation(Allen-Waller & Barott, 2023;Cameron et al, 2022;Venn et al, 2022). The use of isotopic tools such as the boron pH proxy in the coral skeleton would help that way, via tracing and defining the inputs of specific symbiotic partners into biomineralization mechanisms.…”

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confidence: 99%

Corals adapted to extreme and fluctuating seawater pH increase calcification rates and have unique symbiont communities

Tanvet

Camp

Sutton

et al. 2023

Ecology and Evolution

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Ocean acidification (OA) is a severe threat to coral reefs mainly by reducing their calcification rate. Identifying the resilience factors of corals to decreasing seawater pH is of paramount importance to predict the survivability of coral reefs in the future. This study compared corals adapted to variable pHT (i.e., 7.23–8.06) from the semi‐enclosed lagoon of Bouraké, New Caledonia, to corals adapted to more stable seawater pHT (i.e., 7.90–8.18). In a 100‐day aquarium experiment, we examined the physiological response and genetic diversity of Symbiodiniaceae from three coral species (Acropora tenuis, Montipora digitata, and Porites sp.) from both sites under three stable pHNBS conditions (8.11, 7.76, 7.54) and one fluctuating pHNBS regime (between 7.56 and 8.07). Bouraké corals consistently exhibited higher growth rates than corals from the stable pH environment. Interestingly, A. tenuis from Bouraké showed the highest growth rate under the 7.76 pHNBS condition, whereas for M. digitata, and Porites sp. from Bouraké, growth was highest under the fluctuating regime and the 8.11 pHNBS conditions, respectively. While OA generally decreased coral calcification by ca. 16%, Bouraké corals showed higher growth rates than corals from the stable pH environment (21% increase for A. tenuis to 93% for M. digitata, with all pH conditions pooled). This superior performance coincided with divergent symbiont communities that were more homogenous for Bouraké corals. Corals adapted to variable pH conditions appear to have a better capacity to calcify under reduced pH compared to corals native to more stable pH condition. This response was not gained by corals from the more stable environment exposed to variable pH during the 100‐day experiment, suggesting that long‐term exposure to pH fluctuations and/or differences in symbiont communities benefit calcification under OA.

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“…By the end of this century, under SSP5-8.5 the pH of the surface ocean is expected to decrease by 0.39 relative to 2006–2015 if emissions are not curbed [ 5 ]. Calcifying organisms such as corals can be greatly affected by OA due to their dependance on carbonate for their aragonitic skeletons [ 4 , 6 ] and the increased energetic demand of calcification at low pH [ 7 – 9 ]. However, not all calcifying organisms are negatively affected by OA and some are able to maintain important calcification rates in environments with persistently low pH [ 10 ], possibly due to increased concentrations of bicarbonate [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Elevated heterotrophic capacity as a strategy for Mediterranean corals to cope with low pH at CO2 vents

Hulver,

Carbonne,

Teixidó

et al. 2024

PLoS ONE

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The global increase in anthropogenic CO2 is leading to ocean warming and acidification, which is threatening corals. In Ischia, Italy, two species of Mediterranean scleractinian corals–the symbiotic Cladocora caespitosa and the asymbiotic Astroides calycularis–were collected from ambient pH sites (average pHT = 8.05) and adjacent CO2 vent sites (average pHT = 7.8) to evaluate their response to ocean acidification. Coral colonies from both sites were reared in a laboratory setting for six months at present day pH (pHT ~ 8.08) or low pH (pHT ~7.72). Previous work showed that these corals were tolerant of low pH and maintained positive calcification rates throughout the experiment. We hypothesized that these corals cope with low pH by increasing their heterotrophic capacity (i.e., feeding and/or proportion of heterotrophically derived compounds incorporated in their tissues), irrespective of site of origin, which was quantified indirectly by measuring δ13C, δ15N, and sterols. To further characterize coral health, we quantified energy reserves by measuring biomass, total lipids, and lipid classes. Additional analysis for C. caespitosa included carbohydrates (an energy reserve) and chlorophyll a (an indicator of photosynthetic capacity). Isotopic evidence shows that ambient-sourced Mediterranean corals, of both species, decreased heterotrophy in response to six months of low pH. Despite maintaining energy reserves, lower net photosynthesis (C. caespitosa) and a trend of declining calcification (A. calycularis) suggest a long-term cost to low heterotrophy under ocean acidification conditions. Conversely, vent-sourced corals maintained moderate (C. caespitosa) or high (A. calycularis) heterotrophic capacity and increased photosynthesis rates (C. caespitosa) in response to six months at low pH, allowing them to sustain themselves physiologically. Provided there is sufficient zooplankton and/or organic matter to meet their heterotrophic needs, vent-sourced corals are more likely to persist this century and potentially be a source for new corals in the Mediterranean.

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Proton gradients across the coral calcifying cell layer: Effects of light, ocean acidification and carbonate chemistry

Cited by 12 publications

References 77 publications

Effects of water flow and ocean acidification on oxygen and pH gradients in coral boundary layer

Effects of water flow and ocean acidification on oxygen and pH gradients in coral boundary layer

Corals adapted to extreme and fluctuating seawater pH increase calcification rates and have unique symbiont communities

Elevated heterotrophic capacity as a strategy for Mediterranean corals to cope with low pH at CO2 vents

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