Colony-forming scleractinian cold-water corals (CWCs) are important ecosystem engineers, forming complex 3-dimensional habitats in the deep sea, which in turn sustain high biodiversity. They are threatened by future environmental changes such as ocean acidification, warming, deoxygenation, and food limitation, but little is known about the effect of these drivers in combination or on the long-term. We conducted a year-long aquarium experiment with Lophelia pertusa (syn. Desmophyllum pertusum) under projected end-of-century conditions, investigating the combined effect of differences in pH (8.1 and 7.7), temperature (9°C and 12°C), oxygen concentration (100% and 90%) and food supply (100% and 60%) on coral survival, growth, respiration rates, skeletal dissolution and energetic reserves. Growth rates of L. pertusa decreased significantly in both multiple driver treatments, resulting in negative and more variable growth rates. However, growth rates only started to decrease after 4.5 months, clearly showing a delayed response. In addition, survival rates and energetic reserves were slightly lower in multiple driver treatments, whereas L. pertusa was not affected by reduced oxygen concentration examined as a single factor. Negative growth rates in multiple driver treatments were driven by dissolution of bare skeletal parts due to reduced seawater pH and temporary aragonite undersaturation, visualised here through micro-computed tomography images. While live CWCs may be able to cope with projected future environmental changes over the timescale of 1 year, ocean acidification will lead to dissolution of the dead skeletal framework of CWC reefs and net loss, reducing the complexity and associated biodiversity of these reefs. However, the challenge remains in closing the gap between long-term experiments and the much longer-term chronic exposure of CWCs to projected environmental changes.
Continue reading ‘Skeletal growth and loss of the cold-water coral Lophelia pertusa from multiple environmental drivers in a year-long experiment’Posts Tagged 'corals'
Skeletal growth and loss of the cold-water coral Lophelia pertusa from multiple environmental drivers in a year-long experiment
Published 27 March 2026 Science ClosedTags: biological response, corals, dissolution, growth, laboratory, morphology, mortality, multiple factors, North Atlantic, oxygen, physiology, respiration, temperature
Acidification and deoxygenation matter in assessing redistribution of global cold-water coral biodiversity induced by climate change
Published 24 March 2026 Science ClosedTags: biological response, BRcommunity, corals, globalmodeling, modeling, multiple factors, temperature
The ocean is undergoing significant changes, including warming, acidification, and deoxygenation, which pose great challenges to marine biodiversity. However, most models projecting the impacts of climate change on marine species overlook predictor variables critically meaningful for species’ ecologies such as pH and dissolved oxygen. The recent release of high-resolution projections of different future climate-change scenarios offers the opportunity to explore species redistribution under multiple threats beyond ocean warming. Accordingly, we conducted a global comparative analysis to study the impact of incorporating predictor variables describing pH and dissolved oxygen into marine species distribution models. We used models trained for 268 cold-water coral species to project potential future distributions for different climate and dispersal scenarios over different time periods. We found that, irrespective of scenario or period, models using pH and dissolved oxygen projected 11.5–21.4% higher impacts of climate change than those without them. For instance, by the end of the century under a high emission scenario, models including pH and oxygen projected an average range contraction of 48.2% for cold-water corals under a no-dispersal scenario, compared with a 26.8% contraction projected by models excluding these two predictors. Given the substantial differences in the predicted distribution patterns and the biological importance of these variables, we highlight that researchers should consider more diverse sets of predictor variables when predicting future range shifts for marine biodiversity assessments under climate change.
Continue reading ‘Acidification and deoxygenation matter in assessing redistribution of global cold-water coral biodiversity induced by climate change’The economic impact of climate change on coral reef in the Main Hawaiian Islands
Published 18 March 2026 Science ClosedTags: biological response, communitymodeling, corals, modeling, multiple factors, North Pacific, socio-economy, temperature
Coral reefs are highly diverse and productive ecosystems that provide a wide range of ecosystem services, including recreation, coastal protection, and marine biodiversity. Climate change impacts, including ocean warming and acidification, pose a significant threat to coral reefs and the ecosystem services they provide. The variability of these impacts underlines the need to develop more spatially explicit tools in coastal ecosystem management that integrate and assess potential ecological and socio-economic outcomes. To address this, a spatially explicit predictive ecological model is applied to project changes in coral reef cover, using downscaled data from Shared Socioeconomic Pathway (SSP) climate scenarios. Based on these projections, welfare impacts of changes in recreational value are estimated across different populations and landscapes. Cumulative welfare losses for Hawaiʻi residents range from $1.5 to $3.3 billion in 2024$ by 2100. Counterintuitively, cumulative welfare losses are higher under optimistic emissions scenarios, where coral reef degradation is less severe than higher emission scenarios, because more people will experience smaller ecological losses. The approach incorporates site-specific characteristics, income distribution, and projected regional population growth to connect ecological change with welfare outcomes. EJScreen is used to assess variation in welfare impacts, identifying disadvantaged communities based on demographic and environmental indicators such as poverty, minority status, and exposure to environmental risks. These findings can inform policy and resource allocation by supporting ecosystem management strategies that account for both ecological dynamics and community-level socio-economic conditions.
Continue reading ‘The economic impact of climate change on coral reef in the Main Hawaiian Islands’Multi-level holobiont dysregulation increases the ecological risk of combined ocean acidification and benzo[a]pyrene pollution to the reef-building coral Porites lutea
Published 17 March 2026 Science ClosedTags: archaea, biological response, BRcommunity, community composition, corals, laboratory, molecular biology, multiple factors, North Pacific, otherprocess, photosynthesis, physiology, phytoplankton, prokaryotes, toxicants
Highlights
- Combined ocean acidification and BaP induce holobiont dysregulation, evidencing by a decoupled Symbiodiniaceae proliferation and a collapse of the archaeal Nanoarchaeota-Halobacterota symbiosis.
- The coral host shifts its defense strategy from antioxidant capacity to cellular homeostasis, while the bacterial community increases functional redundancy, revealing a costly acclimation mechanism.
- The multi-level dysregulation demonstrates an underestimated ecological risk, highlighting that current single-stressor risk assessments are inadequate for protecting corals under complex pollution scenarios.
Abstract
Reef-building corals are increasingly threatened by the combined effects of global climate change and localized organic pollutants. However, the holistic impacts of co-exposure to ocean acidification (OA) and benzo[a]pyrene (BaP) on coral holobionts remain poorly understood. Here, we investigated the multi-level responses of the reef-building coral Porites lutea to short-term (7-day) exposure to OA (pH 7.80), BaP (10 µg/L), and their combination, by integrating physiological measurements with microbiome profiling (ITS2 and 16S rRNA). We found that combined stress was associated with a dysregulated response in Symbiodiniaceae, characterized by a significant increase in cell density without a parallel rise in chlorophyll content, suggesting a possible compensatory but inefficient proliferation response. Despite this, the dominant symbiont Cladocopium C15 remained stable. The bacterial diversity increased (e.g., enrichment of Ruegeria and Acanthopleuribacter, decline of Endozoicomonas), which may suggest enhanced functional redundancy, while the archaeal community was significantly restructured, most notably a marked decline of the putative obligate Nanoarchaeota–Halobacterota symbiosis. At the host level, combined stress was associated with suppressed antioxidant enzyme activities (SOD/POD) but upregulated genes related to protein folding (Hsp90) and calcium homeostasis (NCX1, VAMP4). These findings suggest a complex holobiont reconfiguration under combined stress, involving a stabilized core symbiont, altered microbiomes, and a shifted host defense strategy. Our study suggests that the ecological risk of combined OA and organic pollution may not be extrapolated from single-stressor responses, indicating the need to incorporate multi-stressor frameworks into coral reef risk assessments.
Continue reading ‘Multi-level holobiont dysregulation increases the ecological risk of combined ocean acidification and benzo[a]pyrene pollution to the reef-building coral Porites lutea’Stony coral symbioses show variable responses to future ocean conditions
Published 16 March 2026 Science ClosedTags: adaptation, biological response, BRcommunity, community composition, corals, laboratory, mesocosms, multiple factors, North Pacific, otherprocess, phytoplankton, temperature
Coral reefs support over a quarter of marine species and nearly a billion people worldwide but are also among the ecosystems most threatened by anthropogenic impacts. There is long-standing debate about whether coral symbioses will be disrupted or respond adaptively under future ocean conditions. Using a factorial 2.5-year future-ocean mesocosm experiment across eight coral species representing the major coral lineages, we tracked symbiont community shifts within replicate fragments from the same individual coral. Some corals exhibited stochastic divergence consistent with dysbiosis, whereas others showed deterministic, thermally adaptive shifts. Heat stress generally reduced symbiont diversity and promoted predictable restructuring, supporting deterministic processes under moderate stress but stochastic dysbiosis under extreme conditions. We propose that adaptive and stochastic responses represent endpoints along a continuum of host-orchestrated symbiont sorting. This study bridges coral reef ecology with broader host–microbiome theory, offering an integrated perspective on how symbiotic systems may respond to environmental change.
Continue reading ‘Stony coral symbioses show variable responses to future ocean conditions’Two decades of skeletal density decline in Pocillopora spp. corals in the Mexican Pacific Ocean: insight into a tropical eastern Pacific acidification scenario?
Published 10 March 2026 Science ClosedTags: biological response, chemistry, corals, field, morphology, North Pacific
Corals demonstrate vulnerability to environmental changes, exhibiting the capacity to substantially modify coral calcification. In this study, we estimated declines in the density of Pocillopora coral species in the Mexican Pacific. The samples utilized in this study encompass both recently collected corals and those stored in Mexican repositories collected in the northeastern and southern Mexican Pacific regions. Density estimates indicate a 28.6% decline in coral density over the past 23 years (−0.0227 g CaCO3 cm-3 y-1) in the southern Mexican Pacific, while at the entrance to the Gulf of California, density has decreased by 15.4% over the past 20 years (−0.017 g CaCO3 cm-3 y-1). A comprehensive evaluation of environmental data reveals that the observed decline in Pocillopora skeletal density in Mexican Pacific reefs is concomitant with decreases in Ωar and pH, and an increase in ocean temperature on a substantial regional scale. When considered in conjunction with the previously documented reductions in coral growth of Pocillopora spp. skeletons in the eastern Tropical Pacific, our findings indicate a potential decline in CaCO3 production within the region’s reef systems. The results of this study underscore the significance of generating long-term series of coral growth parameters for relevant reef-building species and the carbonate system in key and representative coastal areas, particularly those that are already challenging for coral survival and reef maintenance.
Continue reading ‘Two decades of skeletal density decline in Pocillopora spp. corals in the Mexican Pacific Ocean: insight into a tropical eastern Pacific acidification scenario?’Persistence of coral reef structures into the twenty-first century
Published 2 March 2026 Science ClosedTags: biological response, BRcommunity, corals, review
Coral reefs provide important socioecological services but are vulnerable to climate change, which shifts the balance between the production and erosion of calcium carbonate (CaCO3). In this Review, we summarize understanding of reef accretion, describe the mechanisms of carbonate production and erosion, and consider the effects of future ocean warming and acidification on key reef-building and eroding taxa. The combined stressors of climate change substantially reduce net carbonate production, with a more pronounced effect on calcifying algae than corals. However, declining coral cover driven by marine heatwaves and mass bleaching will probably be the dominant determinant of future reef carbonate budgets, and thus only reefs with thermally adapted populations are predicted to maintain the ability to sustain positive CaCO3 production under climate change, even if calcareous algal cover increases. As carbonate budgets become net negative in the future, the longevity of pre-existing reef frameworks remains unknown and understudied owing to the timescales required to meaningfully assess framework removal rates. Improving estimates of the rates of biologically driven framework loss and chemical dissolution will also be important in better predicting future reef persistence. Key knowledge gaps exist in understanding the effects of deoxygenation on coral reefs, as well as the influence of climate change on understudied sediment-producing taxa such as foraminifera and tropical molluscs.
Continue reading ‘Persistence of coral reef structures into the twenty-first century’Climate change impacts on coral reefs and emerging resilience pathways: a systematic review
Published 25 February 2026 Science ClosedTags: biological response, corals, review
Highlights
- Rising temperatures, acidification, sea level rise and storms are accelerating coral bleaching and reef weakening worldwide.
- Review of 220 studies from 1996–2025 reveals major biodiversity loss and high risk of reef collapse under warming.
- The 2023–2025 global bleaching event impacted about 84 percent of reefs, the most severe on record.
- Coral gardening, larval restoration, assisted evolution and connected marine protected areas boost reef resilience.
- Emission cuts combined with local conservation, community stewardship and adaptive management are vital for reef survival.
Abstract
Coral reefs are one of the ecosystems that are most affected by climate change, but they also support biodiversity, coastal stability, fisheries, and tourism around the world. This review uses a structured narrative literature review based on PRISMA protocols to put together evidence from 220 peer-reviewed articles (1996 to 2025) to see how warming seas, ocean acidification, rising sea levels, and stronger storms change coral ecology, structure, and ecosystem functioning. The results indicate that heightened thermal stress is the principal catalyst of mass bleaching and mortality, occurring with greater frequency and at larger spatial scales, whereas ongoing acidification persists in diminishing calcification, skeletal density, and recruitment success. The rise in sea level and damage caused by storms make habitat loss happen even faster, make reefs less complex, and make communities of reef-associated species less stable. Even though things are going this way, new interventions like coral gardening, larval propagation, assisted evolution, marine protected areas, and community-led co-management show promise for making things more resilient in the face of future climate change. The review emphasizes the necessity of immediate global carbon reduction in conjunction with customized conservation and restoration strategies at the local level. If no strong action is taken, coral reefs may not last long, and the economic security they provide may also go down.
Continue reading ‘Climate change impacts on coral reefs and emerging resilience pathways: a systematic review’Indo-Pacific coral reef sponge diversity declines under predicted future ocean conditions
Published 19 February 2026 Science ClosedTags: abundance, biological response, BRcommunity, community composition, corals, laboratory, mesocosms, multiple factors, North Pacific, otherprocess, porifera, temperature
Future oceans are predicted to favor groups like sponges over calcifying taxa such as scleractinian corals. Here, we test this hypothesis by examining the development of coral reef communities in experimental mesocosms over 23 months. 85 sponge species among the calcifying class Calcarea (~33%), and non-calcifying Demospongiae (~60%) and Homoscleromorpha (<10%) recruited to warming (+2°C), acidification (-0.2 pH), and warming+acidification (+2°C, -0.2 pH) future ocean treatments. The diversity of calcifying sponges was unimpacted across any treatment, whereas non-calcifying classes showed greatest declines. 57-66% of demosponges decreased under future ocean conditions, and homoscleromorphs were entirely absent from acidified treatments. Through the sponge loop, sponges play a fundamental role in coral reef nutrient cycling, and altered coral reef community composition likely has functional consequences. This study challenges the assumption that non-calcifying species are less impacted and highlights the importance of understanding how community composition may alter ecosystem functioning under future ocean conditions.
Continue reading ‘Indo-Pacific coral reef sponge diversity declines under predicted future ocean conditions’Summary of ocean acidification data collected by the National Coral Reef Monitoring Program in the U.S. Pacific Islands, 2021—2023
Published 10 February 2026 Newsletters and reports ClosedTags: biological response, BRcommunity, chemistry, corals, field, North Pacific, primary production
Coral reefs are among the most biologically diverse and economically valuable ecosystems on earth. They provide billions of dollars annually in food, jobs, recreation, coastal protection, and other critical ecosystem services (Brander & van Beukering, 2013; Costanza et al., 2014). However, these ecosystems are also among the most vulnerable to ocean acidification (OA). Even under the most optimistic model projections, increasing atmospheric and seawater carbon dioxide concentrations are likely to occur over the next few decades, decreasing seawater pH and reducing the availability of the carbonate ion (CO32-) building blocks that corals and other marine calcifiers use to construct reef habitat (Chan & Connolly, 2013; Jiang et al., 2023). OA threatens the persistence of coral reefs by reducing rates of coral and crustose coralline algae (CCA) calcification and accelerating rates of bioerosion, thereby lowering net production of calcium carbonate (CaCO3) and compromising the structural complexity and integrity of three-dimensional reef habitat (Cornwall et al., 2021; Hill & Hoogenboom, 2022). As a result, many of the ecological, economic, and cultural values offered by coral reefs could be significantly impacted by OA over the next century.
NOAA’s National Coral Reef Monitoring Program (NCRMP) provides a framework for long-term, national-level monitoring of the U.S.-affiliated coral reef areas. Funded jointly by the NOAA Coral Reef Conservation Program and Ocean Acidification Program, NCRMP assesses the status and trends of U.S. coral reef ecosystems and supports the management of the nation’s reefs (NOAA Coral Program, 2021). NCRMP’s long-term monitoring of OA and related coral reef ecosystem responses (NCRMP-OA) evaluates patterns and trends in carbonate chemistry and key ecosystem indicators across gradients of biogeography, oceanographic conditions, habitat types, and human impacts. These data sets are used to inform the efficacy of place-based coral reef management in close collaboration with federal, state, and jurisdictional partners.
To assess the progression of OA and impacts on coral reef ecosystems in the U.S. Pacific Islands, NCRMP-OA monitoring includes the following objectives:
- Conduct carbonate chemistry sampling to monitor spatial variability and temporal change in pH, aragonite saturation state (Ωar), and other carbon system parameters;
- Conduct diel carbonate chemistry water sampling and oceanographic instrument deployments at select sites;
- Conduct census-based carbonate budget assessments to estimate rates of coral reef biological carbonate production and erosion.
This report summarizes the monitoring effort and results from 2021–2023 NCRMP-OA sampling and surveys. Additional NCRMP environmental, benthic, and fish data are not included in this report, but they can be accessed at the links provided in the Data Availability section.
Continue reading ‘Summary of ocean acidification data collected by the National Coral Reef Monitoring Program in the U.S. Pacific Islands, 2021—2023’Understanding coral health from reactor engineering perspective: multiphysics modeling of coral–environment interactions
Published 30 January 2026 Science ClosedTags: biological response, corals, individualmodeling, modeling, photosynthesis, physiology, respiration
Coral, as a bioreactor, has to continuously interact with surrounding environment to maintain a healthy state. A multi-physics reaction engineering model has been developed to capture this interaction. The coral interior is modeled as interconnected reaction units respectively for photosynthesis, respiration, and calcification, whose reaction kinetics are influenced by environmental fluctuations. Coupling between coral and environment is realized by bi-directional mass transfer at the coral-seawater interface, with consideration of the unique flow fields induced by ciliary beating. By resorting to this comprehensive model, we discover that ciliary beating demonstrates distinctively different diurnal and nocturnal functions. During daytime, beating can help reduce photosynthetic oxygen accumulation to prevent hyperoxia-induced mortality, while enhancing carbon dioxide uptake efficiency to promote nutrient production. At night, however, beating promotes oxygen acquisition for adequate respiration, while expelling carbon dioxide to inhibit symbiotic destruction under acidic stress. The model further enables mechanistic analysis of the detrimental impact of climate change on coral health, where the influences from two key factors (i.e., temperature and CO2 level) can be decoupled. It’s interesting to find out that the elevated temperature plays a dominant role during daytime, while at night the coral is dominantly influenced by rising CO2 level.
Continue reading ‘Understanding coral health from reactor engineering perspective: multiphysics modeling of coral–environment interactions’Ocean acidification modulates material flux linked with coral calcification and photosynthesis
Published 14 January 2026 Science ClosedTags: biological response, calcification, corals, North Pacific, physiology
Coral reefs are essential for the foundation of marine ecosystems. However, ocean acidification (OA), driven by rising atmospheric carbon dioxide (CO2) threatens coral growth and biological homeostasis. This study examines two Hawaiian coral species—Montipora capitata and Pocillopora acuta to elevated pCO2 simulating OA. Utilizing pH and O2 microsensors under controlled light and dark conditions, this work characterized interspecific concentration boundary layer (CBL) traits and quantified material fluxes under ambient and elevated pCO2. The results of this study revealed that under increased pCO2, P. acuta showed a significant reduction in dark proton efflux, followed by an increase in light O2 flux, suggesting reduced calcification and enhanced photosynthesis. In contrast, M. capitata did not show any robust evidence of changes in either flux parameters under similar increased pCO2 conditions. Statistical analyses using linear models revealed several significant interactions among species, treatment, and light conditions, identifying physical, chemical, and biological drivers of species responses to increased pCO2. This study also presents several conceptual models that correlate the CBL dynamics measured here with calcification and metabolic processes, thereby justifying our findings. We indicate that elevated pCO2 exacerbates microchemical gradients in the CBL and may threaten calcification in vulnerable species such as P. acuta, while highlighting the resistance of M. capitata. Therefore, this study advances our understanding of how interspecific microenvironmental processes could influence coral responses to changing ocean chemistry.
Continue reading ‘Ocean acidification modulates material flux linked with coral calcification and photosynthesis’A trend-based ecological indicator framework for spatially classifying ocean acidification risk to global coral reefs
Published 8 January 2026 Science ClosedTags: biological response, chemistry, corals, policy, review
Highlights
- Global aragonite saturation state declined at −0.0068 ± 0.00013 yr−1 from 1985 to 2023.
- Equatorial Pacific shows fastest acidification with Ωₐᵣ declines of −0.012 yr−1.
- Novel trend-based K-means clustering identifies emerging coral reef risk zones.
- Strong pCO₂-Ωₐᵣ correlations (ρ < −0.9) in tropical upwelling regions monthly.
- Framework supports SDG 14.3 and Global Biodiversity Framework implementation.
Abstract
Ocean acidification driven by anthropogenic CO₂ uptake poses a critical threat to coral reef ecosystems. Using global surface ocean carbonate data from 1985 to 2023, we provide a high-resolution, observation-based assessment of long-term trends in pCO₂, pH, and aragonite saturation state (Ωₐᵣ). Our results show a robust global decline in Ωₐᵣ (−0.0068 ± 0.00013 yr−1), with the most pronounced losses in the equatorial Pacific and Southern Hemisphere. Monthly correlations reveal strong inverse pCO₂–Ωₐᵣ relationships (ρ < −0.9) and positive pH–Ωₐᵣ correlations (ρ > 0.9) in tropical upwelling zones, highlighting spatially persistent acidification stress. A key innovation of this study is the use of a trend-based K-means clustering framework that classifies ocean regions into high, moderate, and low impact categories based on Ωₐᵣ decline rates. Unlike conventional assessments relying on absolute Ωₐᵣ thresholds, this approach identifies regions that remain suitable today but are deteriorating rapidly, thus at risk of crossing biological thresholds in the near future. High-impact zones, including the Coral Triangle and eastern tropical Pacific, show Ωₐᵣ declines of −0.010 to −0.012 yr−1 and have already reached levels near 2.4–3.0, suggesting growing stress on reef calcification. By leveraging high-resolution observational data rather than model projections, this approach reduces uncertainty and offers a scalable tool for anticipating ecological vulnerability under ongoing acidification. The findings underscore the urgent need for conservation in tropical high-impact zones and for sustained monitoring in lower-risk regions. This work provides a science-based framework to support spatially targeted reef management and informs global policy priorities including SDG 14.3 and the Global Biodiversity Framework.
Continue reading ‘A trend-based ecological indicator framework for spatially classifying ocean acidification risk to global coral reefs’Assessing the influence of ocean acidification on the deterioration of coral reefs in Sri Lanka
Published 1 January 2026 Science ClosedTags: biogeochemistry, biological response, chemistry, corals, field, Indian, review
Rising atmospheric CO2 levels have significantly increased ocean acidification (OA), endangering coral reefs, and nutrient (nitrate (NO3−), and phosphate (PO43−)) pollution also weakens the coral reef resilience. Therefore, the study evaluates the prevailing OA level over the Sri Lankan coral reef areas using the aragonite saturation state (ΩAr) and assesses the nitrate (NO3−), and phosphate (PO43−) concentrations over the coral sites. The study was conducted on coral reefs on the eastern coast (EC), southern coast (SC), northern coast (NC), and west coast (WC) of Sri Lanka from April to June 2024. A total of 63 seawater samples were collected around each coastal site for analysis. The Ω Ar were supersaturated (ΩAr> 1) and ranged from 2.98±0.04 to 4.92±0.12. Throughout the study period, the study sites had ΩAr values exceeding 2.92±0.16, indicating that the nation’s corals were resilient to deterioration, and the comparative analysis demonstrates that these sites were not vulnerable to OA. The NO3− concentrations of 2–5 µmol L− 1, from human activities, may intensify coral bleaching during heat stress. Results showed that SC (2.19±1.28 µmol L− 1) and WC (3.52±1.48 µmol L− 1) had NO3− above the permissible range, which may be due to waste discharge and high runoff. The significantly higher PO43− concentrations were reported in EC (0.35±0.07 µmol L− 1). Coral bleaching hotspot (HS) identification emphasizes how spatially distributed HS are from January to June. The OA risk assessment confirmed that climate change brought high risk to the coral reef ecosystems, which impact on the ecology and economy of Sri Lanka.
Continue reading ‘Assessing the influence of ocean acidification on the deterioration of coral reefs in Sri Lanka’The role of heterotrophy in the response of Oculina arbuscula to ocean acidification
Published 31 December 2025 Science ClosedTags: biological response, BRcommunity, calcification, corals, laboratory, multiple factors, North Atlantic, physiology, phytoplankton
On both tropical and temperate reefs, the calcium carbonate skeletons produced by scleractinian corals provide habitat that supports a high biodiversity of fishes and invertebrates. Ocean acidification (OA), driven by excess anthropogenic CO2 uptake, causes declines in seawater pH and carbonate ion concentration and can compromise coral calcification by causing increased energetic demands. Deciphering how corals meet this increased energetic demand is critical to predicting their future persistence. Oculina arbuscula is a facultatively symbiotic temperate coral common on subtropical reefs of the South Atlantic Bight. This coral has demonstrated calcification resilience to reduced pH conditions in both symbiotic and aposymbiotic forms, despite aposymbiotic colonies lacking access to photosynthetically-derived energy. I hypothesized that energy acquired through heterotrophy is a mechanism by which O. arbuscula obtains the resources necessary to overcome the heightened energy demand created by ocean acidification. To investigate the role of heterotrophy, a 90-day laboratory experiment was conducted exposing aposymbiotic O. arbuscula fragments to a pH of either 7.7 or 8.0 under three different feeding levels of Artemia spp. nauplii. Although fragments with greater food consumption showed significantly higher calcification rates, this effect was independent of pH. Similarly, biochemical analyses indicated that total protein and total carbohydrate stores increased with higher food consumption but were unaffected by pH exposure. In contrast, total lipid stores decreased during the experiment, regardless of pH exposure or food level, suggesting the heterotrophic contribution to lipid stores was deficient. Together, these results indicate that while heterotrophically-derived energy may not be a primary mechanism underlying the ability of O. arbuscula to sustain calcification rates under OA stress, this coral species should continue to thrive in an increasingly acidifying ocean as long as heterotrophic food resources are in abundance.
Continue reading ‘The role of heterotrophy in the response of Oculina arbuscula to ocean acidification’Compound hypoxia with heat or acidification stress induces synergistic and additive effects on coral physiology
Published 26 December 2025 Science ClosedTags: biological response, BRcommunity, corals, laboratory, morphology, multiple factors, North Atlantic, oxygen, photosynthesis, physiology, phytoplankton, respiration
As climate change accelerates, coastal marine ecosystems are increasingly exposed to co-occurring stressors whose combined effects are nonlinear and difficult to predict. Deoxygenation is a rapidly intensifying yet underrecognized threat to coral reefs that interacts with heat and acidification to alter coral physiology and stress resilience. However, the effects of hypoxia-related compound events on corals are largely unknown, underscoring the need for multi-stressor studies. Here, we conducted two extended-exposure experiments (12–17 days) across the coral species Porites furcata, Porites astreoides and Siderastrea siderea, to disentangle the individual and combined effects of low dissolved oxygen (hypoxia) with either heat or acidification. We measured eight phenotypic traits related to growth, metabolism, and symbiosis health to test whether hypoxia imposes energetic constraints or other physiological stress that amplify the effects of heat or acidification. Standardized effect size analysis across 24 stressor–trait combinations revealed 13 additive, 10 synergistic, and only one antagonistic response. Hypoxia consistently suppressed dark respiration by 37–49% across species and altered photophysiology in the two Porites species, whereas acidification alone had minimal effects, particularly in S. siderea. Heat stress caused the most pronounced declines across nearly all traits, and when combined with hypoxia, it produced the highest number of synergistic interactions. In contrast, the combination of hypoxia and acidification largely resulted in additive responses, suggesting that independent physiological mechanisms underlie these effects. All corals showed strong metabolic depression under hypoxia which is likely beneficial as a short-term adaptive response but may impose energetic constraints in the long-term. These findings highlight deoxygenation as critical yet often overlooked drivers of coral reef vulnerability. More multi-stressor experiments across a range of species are urgently needed to improve predictions of reef resilience under future ocean conditions, where compound stress events are expected to become more frequent and severe.
Continue reading ‘Compound hypoxia with heat or acidification stress induces synergistic and additive effects on coral physiology’Tiny cup corals show accelerating ocean acidification in the Salish Sea (radio)
Published 24 December 2025 Media coverage ClosedTags: corals, North Pacific
Ocean acidification is sometimes described as climate change’s evil twin. The ocean absorbs carbon dioxide from fossil fuel emissions, causing the water to become more corrosive.
“Ocean acidification is already impacting the growth of oysters, clams, plankton, which in turn are important food sources for salmon, seabirds and other marine organisms,” said Mary Margaret Stoll, who just received her Ph.D. from the University of Washington and is the lead author on a new study of ocean acidification, published in the journal Nature Communications.
Stoll said her love of chemistry, physics and biology led to a fascination with ocean acidification. She joined a project that was looking broadly at how ocean acidification is unfolding in the Salish Sea, which borders British Columbia and Washington state. The wind and ocean currents here cause regular upwellings of carbon rich waters from the deep, influenced by the powerful California Current that causes similar conditions off that coast.
To better understand the region’s chemical trajectory, Stoll got to work with a set of artifacts that were collected 130 years ago: the skeletons of native orange cup corals. Naturalists aboard the USS Albatross — a tall ship on a mission to survey halibut for the federal government — had the foresight to keep them.
Stoll said she’s still amazed that this un-commissioned collection was available to her in the archives of the Smithsonian.
“These corals were incredibly well preserved, and there was so much information attached to them as well — about the depths of collection and where they were collected, and when they were collected, how they were cleaned and preserved,” Stoll said.
Stoll and her team painstakingly practiced their knife skills before slicing tiny samples from the 130-year-old specimens in their lab at the University of Washington. Then, they followed the path that the USS Albatross had sailed through the Salish Sea to get modern coral samples that matched those locations, depths and species.
Continue reading ‘Tiny cup corals show accelerating ocean acidification in the Salish Sea (radio)’Differing proteome responses to ocean acidification between two common pocilloporid corals
Published 24 December 2025 Science ClosedTags: adaptation, biological response, corals, laboratory, otherprocess, physiology, South Pacific
Ocean acidification threatens coral reef ecosystems by challenging calcification processes fundamental to reef accretion. Yet many corals continue to calcify under elevated pCO2, suggesting species-specific physiological plasticity and potential cellular compensations. Here, we use label-free quantitative proteomics to investigate proteomic responses of two common pocilloporid corals, Stylophora pistillata and Pocillopora damicornis, with known differential resistance to ocean acidification after two months at moderate (~ 940 ppm) and high (~ 2,800 ppm) pCO2 compared to the control (~ 480 ppm). S. pistillata exhibited extensive proteomic restructuring under high pCO2, marked by widespread declines of energy-generating pathways, yet selective increase of proteins involved in ion transport, cytoskeletal stability, and stress responses. This indicates a strategy of general metabolic suppression coupled with targeted investment into essential cellular functions, potentially sustaining calcification despite reduced overall metabolic capacity. In contrast, P. damicornis showed much less proteomic adjustment, primarily involving structural proteins and those potentially linked to cellular redox balance, signifying a moderate, targeted strategy for physiological stability. These divergent responses highlight contrasting modes of resistance (plasticity versus stability). Integrated with physiological data, our findings clarify cellular mechanisms controlling calcification, demonstrating the value of proteomics in coral ecophysiology and providing new insights into species-specific vulnerability under future ocean conditions.
Continue reading ‘Differing proteome responses to ocean acidification between two common pocilloporid corals’Genotype and symbiont composition rather than environment influence susceptibility to stony coral tissue loss disease in coral restoration broodstock
Published 19 December 2025 Science ClosedTags: biological response, BRcommunity, corals, multiple factors, North Atlantic, performance, phytoplankton, temperature
Over the last several decades, Florida’s Coral Reef has been impacted by global and local stressors causing significant declines in living coral with no signs of natural recovery. Ocean warming, ocean acidification, and infectious diseases are major contributors to the precipitous loss of corals within this region. Since 2014, the stony coral tissue loss disease (SCTLD) outbreak has been particularly devastating, causing unprecedented mortality in over 20 massive coral species. As SCTLD is now endemic in the region, and threats from climate change are likely to persist, studying the disease susceptibility of different coral genotypes under future environmental scenarios is vital for effective restoration. Here, we exposed Orbicella faveolata and Pseudodiploria clivosa genotypes to wild colonies showing signs consistent with SCTLD immediately following a 2-month long exposure to ocean warming (OW) and ocean acidification (OA) scenarios. Corals were exposed to SCTLD for 3 weeks while maintaining the environmental treatments. For both species, pre-exposure to OW and OA scenarios did not make corals more susceptible to SCTLD. However, three genotypes hosting higher levels of Breviolum were at increased risk for showing SCTLD signs under these conditions. One O. faveolata genotype was consistently resistant to SCTLD under the different scenarios, suggesting that natural levels of resistance exist in coral restoration broodstock. Understanding why this genotype could withstand exposure to these stressors may be critical for ensuring survival of restored populations into the future.
Continue reading ‘Genotype and symbiont composition rather than environment influence susceptibility to stony coral tissue loss disease in coral restoration broodstock’Volcanic bubbles in Papua New Guinea a window into coral’s future
Published 9 December 2025 Press releases ClosedTags: corals, South Pacific, vents
By the end of this century, coral reefs in Australia and around the world could be slower to recover, structurally simpler, and increasingly dominated by fleshy algae as rising carbon dioxide reshapes ocean chemistry.
These are the predictions that new international research – published this week in Communications Biology – is warning against, as scientists present a volley of stark new findings about the current and long-term impact of a process known as ocean acidification.
As the oceans absorb more carbon dioxide from the atmosphere, they are becoming increasingly acidic – eroding the very calcium carbonate skeletons that build coral reefs. Yet despite decades of laboratory studies and ecosystem models, scientists have lacked real-world systems that reflect how entire reef communities respond to these long-term chemical shifts.
Researchers from the Australian Institute of Marine Science (AIMS) have now filled that gap by studying shallow-water reefs naturally bathed in volcanic CO₂. These reefs, located near remote submarine vents in Papua New Guinea’s Milne Bay Province, experience chronic exposure to elevated carbon dioxide, offering scientists a rare preview of the seascapes expected under future emissions scenarios.
Continue reading ‘Volcanic bubbles in Papua New Guinea a window into coral’s future’
