The ongoing changes in climate have led to a significant increase in atmospheric CO₂ levels, resulting in ocean acidification, a process that is having profound effects on marine biodiversity, particularly on coral reef ecosystems. Coral reefs, one of the most diverse ecosystems on the planet, are increasingly vulnerable to rising ocean temperatures and the decrease in ocean pH caused by increased carbon dioxide absorption. This paper explores the interconnectedness between ocean acidification, climate change, and the health of coral reef ecosystems, focusing on the impact of reduced pH levels on marine species’ survival, reproduction, and overall biodiversity. We also examine the potential long-term consequences for human communities that depend on these ecosystems for food, tourism, and coastal protection. Through a synthesis of recent studies, this paper aims to provide a comprehensive understanding of the mechanisms by which climate change is reshaping marine life and the urgent need for mitigation and adaptation strategies to safeguard marine biodiversity.
Continue reading ‘Climate change and its impact on marine biodiversity: a study of ocean acidification and coral reef health’Posts Tagged 'corals'
Climate change and its impact on marine biodiversity: a study of ocean acidification and coral reef health
Published 14 May 2025 Science ClosedTags: biological response, BRcommunity, corals, review
Increasing acidification does not affect sexual reproduction of a solitary zooxanthellate coral transplanted at a carbon dioxide vent
Published 8 May 2025 Science ClosedTags: biological response, corals, field, Mediterranean, morphology, reproduction, vents
The absorption of atmospheric carbon dioxide is causing significant changes to the carbonate chemistry of the ocean, in a phenomenon called ocean acidification. The latter makes it potentially more difficult for marine calcifiers like corals, to build their calcium carbonate structures, thus affecting their ability to survive and reproduce. Research on how ocean acidification impacts coral sexual reproduction has focused on tropical species investigated under controlled conditions in aquaria, lacking insights into the intricate natural environment. Here we show that the sexual reproduction of the zooxanthellate solitary scleractinian Balanophyllia europaea transplanted at a CO2 vent off the Island of Panarea (Tyrrhenian Sea, Italy) for up to 5 months is unaffected by decreasing pH (pH range 8.1–7.4). These findings reinforce earlier evidence, suggesting that zooxanthellate corals may exhibit a certain degree of short-term resilience to ocean acidification. However, the interplay between ocean acidification and additional environmental stressors, including warming, will ultimately define the boundaries that distinguish winners and losers amid swift climatic changes.
Continue reading ‘Increasing acidification does not affect sexual reproduction of a solitary zooxanthellate coral transplanted at a carbon dioxide vent’High heterotrophic capacity favors Mediterranean coral success and resilience in the face of ocean acidification
Published 7 May 2025 Science ClosedTags: biological response, corals, field, Mediterranean, physiology, vents
Coral ecosystems support a diverse array of marine life and healthy ecological functioning, yet they are vulnerable to decreases in ocean pH caused by anthropogenic carbon dioxide emissions. In temperate rocky reefs of the Mediterranean, the corals Cladocora caespitosa and Astroides calycularis live at sites with ambient seawater pH and at adjacent submarine volcanic CO2 vent sites with low seawater pH where it is more energetically demanding to grow. We collected corals from distinct ambient pH (average pHT 8.05) and lower pH CO2 vent sites (average pHT 7.74–7.90) and quantified their physiological health and heterotrophic capacity (i.e., feeding capacity). Both species at CO2 vent sites had higher heterotrophic capacity than their ambient site counterparts, enabling them to maintain energy reserves. Our results indicate that high heterotrophic capacity underlies the success of these two temperate corals at CO2 vent sites. Therefore, conservation of CO2 vent coral could be strategically important to maintaining rocky reef ecosystem function and ecological resilience in the Mediterranean.
Continue reading ‘High heterotrophic capacity favors Mediterranean coral success and resilience in the face of ocean acidification’Corals in ocean acidification and the role of calcium ion homeostasis to maintain calcification
Published 21 April 2025 Science ClosedTags: biological response, corals, physiology, review
Coral calcification is essential to provide the structural foundation for coral reefs and is integral in supporting marine biodiversity reliant on reef ecosystems. The drivers for calcification in corals are undoubtedly highly complex and require several perspectives to identify vulnerabilities in the context of environmental change. Specifically, ocean acidification (OA) resulting from the rise of anthropogenic carbon dioxide (CO2) emissions poses a potential threat to the physiological mechanisms that drive calcification in corals. Therefore, this report goes beyond environmental seawater chemistry to examine the physiological mechanism of calcium ion homeostasis. Calcium’s role in calcification physiology is well established, but how calcium homeostasis could shift under acidification has little been considered a significant driver in reduced calcification. Calcium is potentially the most actively transported substrate in coral calcification, though in high chemical abundance in seawater, corals are likely utilizing the most energy to concentrate calcium at the site of calcification. We argue for increased consideration of the calcium ion in the context of OA when identifying sensitivities. The concepts proposed here are justified through a combination of results from novel RAMAN spectroscopy and molecular work that provides insight into shifts in calcium homeostasis when exposed to acidification. We speculate that future work incorporating methodologies considering calcium dynamics in OA could benefit by narrowing in on what physiological mechanisms are potentially vulnerable. It is imperative that we identify what drives lower calcification in corals under OA to inform efficient directives in identifying species sensitivities to future climate change.
Continue reading ‘Corals in ocean acidification and the role of calcium ion homeostasis to maintain calcification’Skeletal morphometrics suggests high fitness of hybrid coral recruits under ocean warming and acidification
Published 10 April 2025 Science ClosedTags: biological response, BRcommunity, corals, laboratory, morphology, multiple factors, South Pacific, temperature
Anthropogenic greenhouse gas emissions increase sea surface temperature and acidification, inhibiting calcification of reef-building corals. While ocean acidification is known to hinder skeletal development of newly settled coral recruits, little is known of its effects on older purebred or interspecific hybrid recruits, or its combined effects with temperature. Using 3D X-ray microscopy, we found that predicted mid-century ocean warming and acidification conditions (28 °C, 685 ppm pCO2) negatively affected the skeletal development of 7-month-old Acropora purebreds and hybrids in one direction (Acropora cf. kenti mother x Acropora loripes father). Conversely, the skeletal parameters of reciprocal hybrids (A. loripes mother x A. cf. kenti father) remained unaffected. Skeletal measurements taken from 3D data revealed patterns overlooked by previous 2D measurements, leading support to the likelihood of hybrid vigour in hybrids of A. loripes (mother) and A. cf. kenti (father) and the potential of interspecific hybridization as a reef restoration tool to enhance coral resilience.
Continue reading ‘Skeletal morphometrics suggests high fitness of hybrid coral recruits under ocean warming and acidification’Cold seeps and coral reefs in northern Norway: carbon cycling in marine ecosystems with coexisting features
Published 31 March 2025 Science ClosedTags: biogeochemistry, biological response, chemistry, corals, field, North Atlantic
Abstract
Cold seeps and cold-water corals (CWCs) coexist on Northern Norway’s continental shelf at the Hola trough between Lofoten and Vesterålen. Here, cold seeps release methane from the seabed, yet none reaches the sea surface. Instead, the methane dissolves and disperses in the ocean where it is ultimately consumed by methane-oxidizing microorganisms. These microorganisms metabolize methane and release carbon dioxide and dissolved organic matter (DOM), which may impact the biogeochemical habitat of CWCs in close vicinity of cold seeps. We investigated the biogeochemistry of carbon, carbon isotopes, nutrients, DOM compositions, and microbial diversity in the water column. Our results indicated that dissolved inorganic carbon concentrations were 29% higher near cold seeps with modified carbon’s isotopic compositions. The hydrophysical parameters and surface-to-bottom control of sinking particles mainly govern water column productivity and nutrient cycle. DOM compositions implied that the seep-associated microbiomes modify DOM’s chemical diversity and isotopic composition at CWCs and the entire water column near cold seeps. Cold seeps and CWCs coexist in Northern Norway’s continental shelves; however, enhanced water temperatures and consequent increase in methane release at cold seeps may modify the carbon cycling in the area, which could mitigate the ecological role and functioning of CWC reefs in the future.
Plain Language Summary
Cold seeps are geological features that release methane from the seabed to the water column. In oxygenated sea water column, seeping methane is consumed by specialized microbes that convert it into carbon dioxide. Although the increase in carbon dioxide can lead to ocean acidification, cold seeps are often found in the Hola trough of Northern Norway near cold-water corals (CWCs), which are vulnerable to changes in ocean acidity. This raises questions about how these features coexist in the same marine ecosystem and how they impact each other. We investigated the carbon exchange between cold seeps and CWCs by analyzing seawater samples. Our data on nutrients, organic matter, and microbial compositions implied cooccurring carbon processes such as methane oxidation and organic matter synthesis. Notably, cold seeps might support CWCs by producing dissolved organic matter that corals feed on. However, this relationship may be valid for a moderate amount of methane release. If methane release increases, consequent acidification may influence the CWC reefs in the future.
Key Points
- Hola trough of Northern Norway is a natural system offering insights into carbon cycling within coexisting marine ecosystems
- Despite their proximity, cold seeps and coral reefs reveal distinct biogeochemical characteristics in the Hola trough
- Cold seeps and methane oxidation impact the inorganic carbon cycle, yet the exchange of organic carbon might be just as significant
Spatiotemporal dynamics of marine heatwaves and ocean acidification affecting coral environments in the Philippines
Published 21 March 2025 Science ClosedTags: biological response, BRcommunity, chemistry, corals, modeling, North Pacific, regionalmodeling
The coral reefs in the Philippines are facing an unprecedented crisis. This study, based on a comprehensive analysis of marine heatwaves (MHWs), degree heating weeks (DHWs), and ocean acidification (OA) indices derived from satellite observations and reanalysis data, reveals how thermal stress and OA have progressively eroded coral ecosystems from 1985 to 2022. This study analyzed 12 critical coral habitats adjacent to the Philippines. The monthly average sea surface temperature (SST) in the study area ranged from 26.6 °C to 29.3 °C. The coast of Lingayen Gulf was identified as the most vulnerable coral reef site in the Philippines, followed by Davao Oriental and Polillo Island. The coast of Lingayen Gulf recorded the highest total MHW days in 2022, amounting to 293 days. The coast of Lingayen Gulf also reached the highest DHW values in July and August 2022, with 8.94 °C weeks, while Davao Oriental experienced the most extended average duration of MHWs in 2020, lasting 90.5 days per event. Large-scale climate features such as the El Niño–Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) significantly influenced the study area’s SST anomalies and MHW events. High-risk coral bleaching periods, such as 1988–1989, 1998–1999, 2007–2008, and 2009–2010, were characterized by transitions from El Niño and positive PDO phases, to La Niña and negative PDO phases. However, since 2015, global warming has led to high cumulative heat stress without specific climate background patterns. We propose a Coral Marine Environmental Vulnerability Index (CoralVI) to integrate the spatiotemporal dynamics of warming and acidification and their impacts on coral habitats. The data show a rapid increase in the marine environmental vulnerability of coral habitats in the Philippines in recent years, extending to almost the entire coastline, posing significant threats to coral survival.
Continue reading ‘Spatiotemporal dynamics of marine heatwaves and ocean acidification affecting coral environments in the Philippines’Quantifying coral-algal interactions in an acidified ocean: Sargassum spp. exposure mitigates low pH effects on Acropora cervicornis health
Published 3 March 2025 Science ClosedTags: algae, biological response, BRcommunity, corals, growth, laboratory, mesocosms, North Atlantic, physiology
Increasingly frequent large-scale pelagic Sargassum algae blooms in the Atlantic have become a problem for coastal ecosystems. The mass decay of these blooms reduces water quality for coastal flora and fauna. However, the effects of living Sargassum blooms on seawater quality and consequently coral reef ecosystems that rely on delicately balanced carbonate chemistry are more ambiguous. Future oceans are predicted to be more acidic as additional anthropogenic CO2 emissions are absorbed, potentially tipping the balance in favor of algal blooms at the cost of coral survival. This study aimed to simulate the indirect interaction between pelagic Sargassum spp. and Acropora cervicornis coral fragments from the Florida Reef in current-day and future ocean pH conditions over the course of 70 days in a mesocosm experimental system. Measurements of coral growth and health via buoyant weight and Pulse Amplitude Modulated (PAM) fluorescence measurements reveal an unexpected coral-algal interaction. After 1 month, coral growth was significantly reduced under ocean acidification conditions and exposure to Sargassum; at the same time quantum yield and maximum electron transport rate of photosynthesis were increased relative to control counterparts in ambient and future pH scenarios by up to 14% and 18% respectively. These improvements in photosynthetic efficiency did not translate to significant differences in growth by the final measurement time point. In addition, the presence of Sargassum spp. did not raise seawater pH in the system, raising questions about how it benefited photosynthetic efficiency in exposed corals. Heterotrophy of detrital algal matter is suspected to compensate for impaired photosynthesis of pH stressed corals. Therefore, despite their current negative reputation, Sargassum blooms could provide short term localized benefits to corals in present and future ocean conditions.
Continue reading ‘Quantifying coral-algal interactions in an acidified ocean: Sargassum spp. exposure mitigates low pH effects on Acropora cervicornis health’High-resolution temporal assessment of physicochemical variability and water quality in tropical semi-enclosed bays and coral reefs
Published 24 February 2025 Science ClosedTags: biological response, BRcommunity, chemistry, community composition, corals, field, North Atlantic, otherprocess
Highlights
- Mangrove, seagrass, and coral habitats are at risk from global and local stressors
- We assessed >20 (a)biotic parameters and pollution at high temporal resolution
- Strong diel and seasonal variability was recorded in semi-enclosed bays
- The bays showed higher nutrient levels and ecotoxicological risks than nearby reefs
- A water quality monitoring framework for reef-associated habitats is provided
Abstract
Tropical coastlines featuring mangrove, seagrass, and coral habitats are of immense ecological and socio-economic importance, supporting biodiversity, carbon storage, coastal protection, fisheries, and tourism. However, climate change, coastal development, and low water quality increasingly threaten these interconnected coastal ecosystems, particularly in semi-enclosed bays where the impacts of these stressors are often amplified. Yet, physicochemical conditions are rarely assessed at sufficient temporal resolution (i.e., diel and seasonal variation) and time-integrated pollution monitoring is rarely performed. Here, we used a multi-disciplinary approach to assess >20 abiotic parameters characterizing two mangrove- and seagrass-dominated inland bays and two nearby coral reefs in Curaçao (southern Caribbean) during the cool, dry season and warm, wet season. This was combined with time-integrated pollution monitoring using bioindicators to assess nutrients and trace metal pollution (inland bays only), and passive samplers and bioassays to assess organic chemical pollution (all four sites) during the wet season. This approach revealed a previously undocumented extent of strong diel and seasonal environmental variability in Curaçao’s inland bays, with temperature, pH, and dissolved oxygen frequently reaching values predicted under moderate-to-severe future climate scenarios as outlined by the IPCC (2021). In addition, the inland bays had greater nutrient concentrations (especially ammonium) and potential ecotoxicological risks than the nearby reefs during the wet season due to run-off and anthropogenic activities. These findings emphasize the importance of high-resolution monitoring to understand risks across appropriate temporal scales and establish an environmental baseline against which future monitoring can be benchmarked. Moreover, our study provides a robust water quality assessment framework that can be used by natural resource managers to monitor reef-associated habitats and conserve their high ecological and socio-economic value. Overall, our work highlights the urgent need to improve monitoring, water quality, and protection of these valuable reef-associated habitats.
Continue reading ‘High-resolution temporal assessment of physicochemical variability and water quality in tropical semi-enclosed bays and coral reefs’Internal hydrodynamics within the skeleton of Acropora pulchra coral
Published 11 February 2025 Science ClosedTags: biological response, corals, dissolution, individualmodeling, modeling
Highlights
- Consistent flow patterns are observed in Acropora coral CT scans-based simulations
- Implications of these patterns for coral growth are discussed in detail
- A prediction of coral skeleton dissolution under ocean acidification is presented
Summary
Many marine life forms, like Acropora coral, develop abiotic components to host and support the growth of living organisms. Using numerical models based on real coral samples reconstructed from micro-computed tomography (CT) scan images, we simulated internal flows inside the skeletons of Acropora pulchra coral under the influence of ambient ocean currents. The results showed that the coral’s skeletal structure, with specially connected pore space, leads to the flow and material transport within and through the skeleton to assist the coral growth and stability. However, under intensified ocean acidification, the skeletal internal flow may induce the dissolution of aragonite inside the skeleton and weaken the whole coral structure.
Continue reading ‘Internal hydrodynamics within the skeleton of Acropora pulchra coral’Considerations for determining warm-water coral reef tipping points
Published 10 February 2025 Science ClosedTags: biological response, BRcommunity, corals, multiple factors, review
Warm-water coral reefs are facing unprecedented human-driven threats to their continued existence as biodiverse functional ecosystems upon which hundreds of millions of people rely. These impacts may drive coral ecosystems past critical thresholds, beyond which the system reorganises, often abruptly and potentially irreversibly; this is what the Intergovernmental Panel on Climate Change (IPCC, 2022) define as a tipping point. Determining tipping point thresholds for coral reef ecosystems requires a robust assessment of multiple stressors and their interactive effects. In this perspective piece, we draw upon the recent global tipping point revision initiative (Lenton et al., 2023a) and a literature search to identify and summarise the diverse range of interacting stressors that need to be considered for determining tipping point thresholds for warm-water coral reef ecosystems. Considering observed and projected stressor impacts, we endorse the global tipping point revision’s conclusion of a global mean surface temperature (relative to pre-industrial) tipping point threshold of 1.2 °C (range 1–1.5 °C) and the long-term impacts of atmospheric CO2 concentrations above 350 ppm, while acknowledging that comprehensive assessment of stressors, including ocean warming response dynamics, overshoot, and cascading impacts, have yet to be sufficiently realised. These tipping point thresholds have already been exceeded, and therefore these systems are in an overshoot state and are reliant on policy actions to bring stressor levels back within tipping point limits. A fuller assessment of interacting stressors is likely to further lower the tipping point thresholds in most cases. Uncertainties around tipping points for such crucially important ecosystems underline the imperative of robust assessment and, in the case of knowledge gaps, employing a precautionary principle favouring lower-range tipping point values.
Continue reading ‘Considerations for determining warm-water coral reef tipping points’Coral skeletal isotopes (δ¹³C and δ¹¹B) as indicators of seawater light attenuation and pH chemistry in the Singapore Strait
Published 4 February 2025 Science ClosedTags: biological response, chemistry, corals, field, paleo, physiology
This study investigates the interaction between δ¹³C and δ¹¹B with terrigenous carbon dynamics in the Singapore Strait, a region characterized by distinct monsoon patterns and significant terrigenous input from surrounding peatlands. We hypothesized that elevated levels of colored dissolved organic matter (CDOM) during the Southwest Monsoon would decrease light penetration, leading to more negative δ¹³C values in coral skeletons. Additionally, we expected that remineralization of terrigenous dissolved organic matter (tDOM) would acidify seawater, resulting in more negative δ¹¹B values in corals. Analysis of Porites spp. corals from two plug cores (KUK and KUL) and seawater data from Kusu Island (2017-2020) revealed no significant correlation between CDOM and coral δ¹³C anomalies— deviations between coral skeletal δ¹³C values and the δ¹³C values of dissolved inorganic carbon (DIC) in seawater— contradicting our hypothesis. Instead, variations in coral δ¹³C appear to be related to a reservoir effect associated with negative δ¹³C in seawater DIC, influenced by tDOC remineralization. Although not statistically significant, the positive correlation pattern observed between δ¹¹B and seawater pH in the KUL core suggests that δ¹¹B might serve as a useful proxy for historical seawater pH and acidification. This finding also supports the idea that Porites corals may regulate their internal pH in response to changes in seawater acidity, potentially influenced by tDOC remineralization. Inconsistencies in the KUK core could be attributed to data offsets from our age-depth model. Further research with extended sampling is needed to confirm δ¹¹B’s sensitivity to pH changes and understand its impact on coral physiology. This study highlights the complex interplay between seasonal changes, carbon dynamics, and coral isotopic records.
Continue reading ‘Coral skeletal isotopes (δ¹³C and δ¹¹B) as indicators of seawater light attenuation and pH chemistry in the Singapore Strait’Conspecific interactions between corals mediate the effect of submarine groundwater discharge on coral physiology
Published 30 January 2025 Science ClosedTags: biological response, BRcommunity, chemistry, corals, field, photosynthesis, physiology, respiration, South Pacific
Land-based inputs, such as runoff, rivers, and submarine groundwater, can alter biologic processes on coral reefs. While the abiotic factors associated with land-based inputs have strong effects on corals, corals are also affected by biotic interactions, including other neighboring corals. The biologic responses of corals to changing environmental conditions and their neighbors are likely interactive; however, few studies address both biotic and abiotic interactions in concert. In a manipulative field experiment, we tested how the natural environmental gradient created by submarine groundwater discharge (SGD) affected holobiont and symbiont metabolic rates and endosymbiont physiology of Porites rus. We further tested how the effect of SGD on the coral was mediated by intra and interspecific interactions. SGD is a natural land-sea connection that delivers nutrients, inorganic carbon, and other solutes to coastal ecosystems worldwide. Our results show that a natural gradient of nutrient enrichment and pH variability as a result of acute SGD exposure generally benefited P. rus, increasing gross photosynthesis, respiration, endosymbiont densities, and chlorophyll a content. Conspecifics in direct contact with the a neighboring coral, however, altered the relationship between coral physiology and SGD, lowering the photosynthetic and respiration rates from expected values when the coral had no neighbor. We show that the response of corals to environmental change is dependent on the types of nearby neighbor corals and how neighbors alter the chemical or physical environment around the coral. Our study underscores the importance of considering biotic interactions when predicting the physiologic responses of corals to the environment.
Continue reading ‘Conspecific interactions between corals mediate the effect of submarine groundwater discharge on coral physiology’Exposure to a gradient of warming and acidification highlights physiological,molecular, and skeletal tolerance thresholds in Pocillopora acuta recruits
Published 21 January 2025 Science ClosedTags: biological response, corals, laboratory, molecular biology, morphology, mortality, multiple factors, North Pacific, reproduction, temperature
Ocean warming and acidification are among the biggest threats to the persistence of coral reefs. Organismal stress tolerance thresholds are life stage specific, can vary across levels of biological organization, and also depend on natural environmental variability. Here, we exposed the early life stages of Pocillopora acuta in Kāne‘ohe Bay, Hawai‘i, USA, a common reef-building coral throughout the Pacific, to projected ocean warming and acidification scenarios. We measured ecological, physiological, biomineralization, and molecular responses across the critical transition from larvae to newly settled recruits following 6 days of exposure to diel fluctuations in temperature and pH in Control (26.8-27.9°C, 7.82-7.96 pHTotal), Mid (28.4-29.5°C, 7.65-7.79 pHTotal) and High conditions (30.2-31.5°C, 7.44-7.59 pHTotal). We found that P. acuta early life stages are capable of survival, settlement, and calcification under all scenarios. The High conditions, however, caused a significant reduction in survival and settlement capacity, with changes in the skeletal fiber deposition patterns. In contrast to a limited impact on the expression of biomineralization genes, the dominant transcriptomic response to the High conditions relative to the two other treatments included depressed metabolism, reduced ATP production and increased activity of DNA damage-repair processes. Collectively, our findings indicate that corals living in environments with large diurnal fluctuations in seawater temperature and pH, such as Kāne‘ohe Bay, can tolerate exposure to moderate projected increased temperature and reduced pH. However, under more severe environmental conditions significant negative effects on coral cellular metabolism and overall organismal survival jeopardize species fitness and recruitment.
Continue reading ‘Exposure to a gradient of warming and acidification highlights physiological,molecular, and skeletal tolerance thresholds in Pocillopora acuta recruits’An environmentally adaptive CRO-SL algorithm based on dynamic agents for the channel assignment problem in wireless networks
Published 15 January 2025 Science ClosedTags: biological response, BRcommunity, communitymodeling, corals, methods, modeling
In recent decades, metaheuristic algorithms have emerged as indispensable tools for addressing complex optimization challenges, particularly in several engineering fields, where NP-hard problems are prevalent. A common NP-hard problem in communication engineering is the Channel Assignment Problem (CAP) for wireless access points (APs), with a determined number of stations (STAs) connected to them. The performance of the complete network depends on the interference and noise among the different clusters of devices and the obstacles or elements placed in the physical transmission space. To address the CAP, a new environmentally adaptive approach is proposed for the Coral Reefs Optimization with Substrate Layers (CRO-SL) algorithm, introducing new environmental agents: algae (representing tabu positions) and ocean water acidification (lowering fitness thresholds). The Environmentally Adaptive CRO-SL (EnvAdapt-CRO-SL) implementation aims to improve solution exploration, enhancing computational efficacy in generating new candidate solutions within the coral reef population. An exhaustive comparative analysis of four configurations of the proposed EnvAdapt-CRO-SL variant assesses the impact of each environmental agent on the algorithm’s performance. Additionally, external benchmarks against four different metaheuristics, along with an analysis of the influence of pseudorandom number generators on initialization and search operators, and a robust optimization case study, provide deeper insights. The results show that incorporating the new environmental agents into the EnvAdapt-CRO-SL workflow significantly boosts throughput while reducing the computational time required to obtain optimal solutions.
Continue reading ‘An environmentally adaptive CRO-SL algorithm based on dynamic agents for the channel assignment problem in wireless networks’From holocene to anthropogenic impact: surpassing coral’s pH up-regulation capacity under ocean acidification
Published 1 January 2025 Science ClosedTags: biological response, corals, laboratory, North Pacific, paleo, physiology
Highlights
- Coral calcifying fluid chemistry during the past ∼5500 years.
- No clear responses of coral CF chemistry to pre-industrial climate shifts.
- Declines in coral pHcf and [CO32−]cf during the CWP.
- A pantropical compilation of δ11B-pHcf matches atmospheric CO2 since Mid-Holocene.
- Limits of corals’ pHcf up-regulation to counteract ocean acidification.
Abstract
Corals’ regulation of internal calcifying fluid (CF or cf) chemistry is crucial for their extraordinary calcification capacity, endowing them with a certain ability to cope with environmental changes such as anthropogenic ocean acidification (OA) and warming. However, it remains unclear whether the impacts of these changes on corals have substantially surpassed their regulation capacity, particularly in comparison to the CF chemistry responses to natural climate variability with minor or no human perturbation. In this study, we reconstructed the pH, dissolved inorganic carbon, and carbonate ion concentrations in coral CF (pHcf, DICcf, and [CO32−]cf) during the Mid- to Late-Holocene, by analyzing the skeletal δ11B and B/Ca of 80 Porites spp. from eastern Hainan Island in the South China Sea (SCS). Our records indicate considerable inter-colony variations in CF chemistry, with maximum disparities reaching 0.18 units for pHcf and 1664 μmol/kg for DICcf. With this in mind, we found no clear responses of coral DICcf to the climate fluctuations during the past ∼5500 years, nor evident differences in pHcf and [CO32−]cf across pre-industrial natural epochs. However, pHcf and [CO32−]cf of modern corals have significantly declined compared to fossil corals. Further analyzes compiling global data on Porites spp. also confirm this pronounced pHcf decrease in modern corals, suggesting the limitations of pantropical corals to counteract OA by up-regulating pHcf. Importantly, these fossil and modern corals reveal a clear long-term pHcf descending trend parallel to atmospheric CO2 changes, supporting the reliability of coral δ11B in recording long-term changes in seawater pH (pHsw).
Continue reading ‘From holocene to anthropogenic impact: surpassing coral’s pH up-regulation capacity under ocean acidification’Characterization of coral communities in the shallow hydrothermal vents of Mabini, Batangas, Philippines
Published 31 December 2024 Science ClosedTags: algae, biological response, BRcommunity, chemistry, community composition, corals, field, growth, North Pacific, reproduction, vents
The existence of shallow hydrothermal vents in Mabini, Batangas, Philippines, has been recognized to contribute to CO2-rich submarine groundwater discharges. However, little is known about the existing coral community structure in the area which provides valuable ecosystem goods and ecological services. We characterized the reef community in this unique microenvironment falls within the predicted future reef condition with low pH and aragonite saturation using coral recruitment tiles, examined coral life-history strategies and size frequency distribution, and measured calcification of transplanted fragments from the genus Goniopora sp., Pectinia sp., and Porites sp. The availability of larval supply has proven that corals can still settle (45–73 recruits m−2) due to the presence of hard substrate and settlement cues such as the crustose coralline algae. The existing coral colonies were mostly dominated by stress-tolerant groups and sizes ranging from 5 to 20 cm. Deployed coral fragments showed growth via extension, and calcification was negatively affected by local conditions, such as Porites sp. fragments. Higher nutrient input may have promoted coral growth, but combined with low carbonate chemistry, it likely made the corals more susceptible to physical damage, as seen on the fragments. This study highlights the importance of naturally occurring extreme environments to determine climate-resilient corals that can adapt to changing conditions and recover from disturbances over time.
Continue reading ‘Characterization of coral communities in the shallow hydrothermal vents of Mabini, Batangas, Philippines’Coexisting mangrove-coral habitats: trends in seawater chemistry and coral diversity
Published 20 December 2024 Science ClosedTags: biological response, BRcommunity, chemistry, corals, field, morphology, phanerogams, South Pacific
Coral reefs face unprecedented threats from climate change, with rising temperatures, ocean acidification, and other stressors endangering their survival. Coexisting mangrove-coral (CMC) habitats provide a natural laboratory to study coral resilience under extreme conditions. However, these habitats are rare and understudied, leaving gaps in understanding their biogeochemical and ecological dynamics. This thesis examines how mangrove proximity influences seawater chemistry, coral diversity, and morphology. A global review identified differences in seawater chemistry between habitat types and regions, driven by biogeochemical processes and freshwater inputs. Edge habitats, particularly in the Great Barrier Reef (GBR), were identified as understudied. An empirical study at Pioneer Bay, GBR, revealed significant spatial and temporal variations in seawater chemistry along a gradient from mangroves to open reefs. Corals near mangroves experienced greater fluctuations in pH, temperature, and oxygen, stabilizing with distance. Tidal flushing mitigated extremes, fostering coral resilience. Mangrove proximity significantly influenced benthic communities, coral morphology, and biodiversity. Extreme conditions near mangroves favored resilient corals like *Porites*, while intermediate sites supported the highest diversity due to nutrient influx and moderate disturbances. Farther sites were dominated by complex coral communities. Edge CMC habitats play a vital role in supporting coral adaptation to climate change. However, intensifying stressors threaten even resilient systems, underscoring the need for long-term monitoring and adaptive management to protect these critical biodiversity hotspots.
Continue reading ‘Coexisting mangrove-coral habitats: trends in seawater chemistry and coral diversity’Projections of coral reef carbonate production from a global climate coral reef coupled model
Published 17 December 2024 Science ClosedTags: biological response, BRcommunity, calcification, communitymodeling, corals, modeling, multiple factors, temperature
Coral reefs are under threat due to climate change and ocean acidification. However, large uncertainties remain concerning future carbon dioxide emissions, climate change and the associated impacts on coral reefs. While most previous studies have used climate model outputs to compute future coral reef carbonate production, we use a coral reef carbonate production module embedded in a global carbon-climate model. This enables the simulation of the response of coral reefs to projected changes in physical and chemical conditions at finer temporal resolution. The use of a fast-intermediate complexity model also permits the simulation of a large range of possible futures by considering different greenhouse gas concentration scenarios (Shared Socioeconomic Pathways (SSPs)), different climate sensitivities (hence different levels of warming for a given level of acidification), as well as the possibility of corals adapting their thermal bleaching thresholds. We show that without thermal adaptation, global coral reef carbonate production decreases to less than 25% of historical values in most scenarios over the twenty-first century, with limited further declines between 2100 and 2300 irrespective of the climate sensitivity. With thermal adaptation, there is far greater scenario variability in projections of reef carbonate production. Under high-emission scenarios the rate of twenty-first century declines is attenuated, with some global carbonate production declines delayed until the twenty-second century. Under high-mitigation scenarios, however, global coral reef carbonate production can recover in the twenty-first and twenty-second century, and thereafter persists at 50-90% of historical values, provided that the climate sensitivity is moderate.
Continue reading ‘Projections of coral reef carbonate production from a global climate coral reef coupled model’Addressing the impact of ocean acidification on coral reefs and marine life: a risk assessment for SDG 14 (life below water)
Published 10 December 2024 Science ClosedTags: biological response, corals, Indian, mitigation, review
One of the main issues emerging from environmental change with significant ramifications for marine life is Ocean acidification. It alludes to the cycle by which the sea turns out to be more acidic because of expansion in the concentration of carbon dioxide in the environment. As carbon dioxide levels ascend in climate a critical part is consumed by the sea which prompts a progression of redox responses that decline the pH of ocean water. This peculiarity has broad ramifications for marine life, especially for coral reefs, which are among the most miscellaneous and monetarily significant biological ecosystems in the world. The purpose of this review is to address and assess the impact of ocean acidification on coral reefs and marine life in order to conserve and sustain marine life below water thus fulfilling Sustainable Development Goal 14 (Life below water).
Continue reading ‘Addressing the impact of ocean acidification on coral reefs and marine life: a risk assessment for SDG 14 (life below water)’
