Metabolomics offers valuable insights into the final stages of biological processes within organisms and holds promise for environmental monitoring. The escalating levels of anthropogenic CO2 due to industrialization are projected to raise atmospheric pCO2 to levels exceeding 1000 ppm by 2100. The ocean absorbs approximately 30% of this increase in CO2, altering seawater chemistry and decreasing pH levels. In this study, untargeted gas chromatography-mass spectrometry (GC–MS) complemented by physio-biochemical analyses, was utilized to explore the impact of elevated pCO2 on the growth, photosynthesis, agar yield and quality, and metabolite composition of the red alga Gracilaria changii. Although elevated pCO2 did not increase the growth rate of G. changii, an increase in the photosynthetic electron transport rate suggests that photosynthetic carbon assimilation was enhanced. The extra photosynthate was used for other cellular processes including proton export to regulate cellular pH homeostasis given the excess H+ in the environment, rather than being invested in new tissue growth. Thymine emerged as a key metabolite influenced by elevated pCO2 in G. changii. Pathway analysis unveiled significant impacts on amino acid synthesis pathways in G. changii at high pCO2. The concentration of compounds such as dopamine and glutamic acid, which are known to be triggered during stress response and provide antipathogenic bioactivity, increased in thalli cultured at higher pCO2. Heatmap analysis indicates d-3 as the turning point for G. changii cultivated at higher pCO2, where the macroalgae begin to regulate their metabolites to alleviate abiotic stresses from higher pCO2 and to maintain essential metabolic functions.
Continue reading ‘Metabolomic profiling of a red alga, Gracilaria changii, under current ambient and elevated pCO2 levels using an untargeted gas chromatography-mass spectrometry (GC–MS) approach’Archive Page 40
Metabolomic profiling of a red alga, Gracilaria changii, under current ambient and elevated pCO2 levels using an untargeted gas chromatography-mass spectrometry (GC–MS) approach
Published 14 April 2025 Science ClosedTags: algae, biological response, growth, laboratory, photosynthesis, physiology
Microbe-host associations as drivers of benthic carbon and nitrogen cycling in a changing Mediterranean Sea
Published 14 April 2025 Science ClosedTags: biological response, BRcommunity, field, Mediterranean, nitrogen fixation, otherprocess, phanerogams, primary production, respiration, vents
Seagrasses, such as the endemic Mediterranean species Posidonia oceanica, are critical components of coastal marine ecosystems, providing essential ecosystem services, including carbon sequestration, nutrient cycling, and habitat formation. P. oceanica forms extensive meadows that serve as biodiversity hotspots and play a crucial role in mitigating climate change through long-term carbon storage. Despite their ecological significance, the interactions between P. oceanica and associated organisms, as well as their combined contributions to biogeochemical cycling, remain poorly understood, particularly under changing environmental conditions. This thesis explores the carbon and nitrogen cycling processes within the P. oceanica holobiont, focusing on the epiphytic and microbial communities, microbial driven metabolic processes, and the interaction between P. oceanica and larger associated invertebrates, such as the sponge Chondrilla nucula. Through field and laboratory experiments, this work demonstrates the significant role of epiphytic algae in the primary production of the seagrass holobiont, contributing a substantial portion of net primary production. Nitrogen cycling processes such as N₂ fixation, nitrification, and denitrification in the seagrass phyllosphere were quantified, revealing their importance in meeting the N demands of the seagrass holobiont, especially under natural ocean acidification conditions. Experiments near marine CO₂ vents indicated that ocean acidification accelerates net primary production and nitrogen cycling, while the structure of the microbial community associated with P. oceanica leaves remains largely stable. The facultative mutualism between P. oceanica and the sponge C. nucula further highlights the complexity of the seagrass holobiont. P. oceanica releases dissolved organic carbon, which meets a portion of the sponge’s respiratory carbon demand. Conversely, C. nucula releases dissolved inorganic nitrogen, including ammonium and nitrate generated by microbial nitrification, which supports seagrass growth. Stable isotope analysis suggests that the association facilitates nutrient exchange, with P. oceanica preferentially absorbing sponge-derived ammonium, while epiphytes may benefit from sponge-produced nitrate. This dynamic reduces seasonal fluctuations in productivity, stabilizing the seagrass ecosystem during periods of senescence. Sponge-associated nitrification contributes to the nitrogen budget of the seagrass holobiont, potentially reducing nutrient limitations in oligotrophic Mediterranean waters. The microbiome of C. nucula plays a key role in these processes, harboring nitrifiers that mediate the production of nitrate. High-throughput sequencing revealed taxonomic diversity among microbes associated with both the sponge and seagrass, including microorganisms involved in carbon and nitrogen cycling processes. These microbial communities not only mediate nutrient exchange within the seagrass-sponge association but also contribute to the overall resilience and productivity of the ecosystem. This thesis highlights the intricate interactions within the P. oceanica holobiont and its nested ecosystem with C. nucula. These findings underscore the importance of microbial and epiphytic communities in maintaining the resilience and productivity of seagrass meadows, particularly in nutrient-poor environments like the Mediterranean Sea. This research enhances our understanding of the biogeochemical processes that support seagrass ecosystem stability and provides valuable insights to guide conservation efforts in the face of climate change and anthropogenic pressures.
Continue reading ‘Microbe-host associations as drivers of benthic carbon and nitrogen cycling in a changing Mediterranean Sea’Benthic biogeochemical processes and fluxes in the hypoxic and acidified northern Gulf of Mexico (nGoM), part I: carbonate dissolution from in situ microprofiles
Published 14 April 2025 Science ClosedTags: biogeochemistry, chemistry, field, North Atlantic
Highlights
- High resolution in situ pH and O₂ microprofiles at the sediment-water interface.
- Benthic measurements of carbonate system parameters, including pH, DIC, TA, Ca2+.
- Large decrease in oxygen concentrations in overlying water, accompanied by DIC accumulation and a pH drop.
- Undersaturation with respect to aragonite and occasionally calcite.
- No significant dissolution of calcium carbonate minerals detected.
Abstract
The northern Gulf of Mexico (nGoM) experiences seasonal coastal hypoxia due to nutrient enrichment from the Mississippi-Atchafalaya River basin, leading to one of the world’s largest hypoxic zones. In these shallow zones, benthic processes play an essential role in driving/maintaining deoxygenation and acidification of bottom waters. In this regard, this paper investigates carbonate dissolution processes in surface sediment of the nGoM during hypoxic conditions in summer 2022, as the main acidification feedback mechanism, with a specific focus on the effects of bottom water acidification. A strong linear relationship is observed between oxygen and pH, with a pH difference of 0.37 between the most oxygenated and the nearly anoxic station, reaching a value of 7.63. Using high-resolution techniques, this study combines pH and O₂ microprofiling (200 μm) with benthic measurements of carbonate system parameters (pH, DIC, TA, Ca2+) to assess carbonate dissolution at millimeter-scale resolution. The pH microprofiles reveal a significant decrease in the first 3 cm, with pore water pH reaching values of 6.90 at the most hypoxic station. Despite undersaturation with respect to aragonite and occasionally calcite, Ca2+ profiles indicate no significant carbonate dissolution, suggesting stability of calcium carbonate in these sediments during the summer. This lack of dissolution, likely influenced by the absence of aragonite, and possible inhibitory effects of dissolved organic carbon and orthophosphate, points to a limited buffering capacity in these sediments. These insights are essential for refining models predicting coastal acidification and hypoxia responses to environmental stressors in the nGoM and similar eutrophic systems.
Continue reading ‘Benthic biogeochemical processes and fluxes in the hypoxic and acidified northern Gulf of Mexico (nGoM), part I: carbonate dissolution from in situ microprofiles’Boron proxies: from calcification site pH to Cenozoic pCO2
Published 14 April 2025 Science ClosedTags: calcification, chemistry, paleo
The atmospheric partial pressure of CO2 (pCO2) is the key driver of climate variability. Boron isotopic compositions (δ11B) of marine calcium carbonates reveal pCO2 of the geologic past because boron isotope incorporation is sensitive to seawater pH, which closely reflects atmospheric pCO2. Biocarbonate δ11B values record environmental pH through a metabolic prism (so called “vital effects”), sometimes complicating interpretations. However, biocarbonate boron isotopes, coupled with boron concentrations (B/Ca), can also reveal the processes of calcification. Here, we review the link between seawater pH and the effective pH recorded by marine organisms via biomineralisation and summarise pCO2 reconstructions from boron isotopes for the Cenozoic (≈70 Ma to modern times), arguably the most significant contribution of this proxy system to date.
Continue reading ‘Boron proxies: from calcification site pH to Cenozoic pCO2 ‘Harpagifer bispinis, but not Patagonotothen tessellata, appears robust to interactive effects of ocean warming and acidification in southern Patagonia
Published 11 April 2025 Science ClosedTags: Antarctic, biological response, fish, laboratory, multiple factors, physiology, temperature
Highlights
- Climate change stressors impaired the thermal physiology of P. tessellata and H. bispinis.
- Their thermal tolerances were more affected by ocean warming than by acidification.
- The interaction of both stressors altered the aerobic scope of P. tessellata.
- H. bispinis appears to be more robust to ocean warming and acidification.
Abstract
Ocean warming and acidification challenge marine ectotherms with rapid, multiple and simultaneous environmental changes. As knowledge of these impacts on fish from the sub-Antarctic is scarce, this study seeks to explore the combined effects of warming and acidification on the thermal and metabolic responses of Patagonotothen tessellata and Harpagifer bispinis, two sympatric notothenioid fish from the Beagle Channel. Juveniles were exposed to present-day and near-future summer temperatures (∼10 and 13 °C) and pCO2 levels (∼500 and 1300 μatm) in a full factorial design. Their critical thermal minimum/maximum (CTmin/CTmax) were assessed and their partial thermal tolerance polygons were estimated. Oxygen consumption rates allowed us to calculate fish’ aerobic scope (AS) as the difference between the standard and maximum metabolic rates (SMR and MMR). The CTmin of both species were affected by temperature, pCO2 level and their interaction, while the CTmax of P. tessellata was affected by both factors and that of H. bispinis, only by temperature. The partial thermal tolerance polygon of P. tessellata significantly decreased with future pCO2 levels, while no changes were observed for H. bispinis. In P. tessellata, SMR and MMR were affected by temperature and pCO2 levels and the AS by their interaction. Conversely, H. bispinis showed no differences in SMR, MMR and AS under different conditions. The increase in SMR and decrease in AS of P. tessellata with future temperatures and pCO2 levels may explain the changes in its thermal tolerance, while for H. bispinis, either the species has a greater capacity to adapt its metabolic response to warming and acidification, or different physiological processes are responsible for the observed changes in its thermal tolerance. Overall, present information could be a valuable tool for forecasting shifts in habitat suitability across the distribution range of both species and other similar fish in the context of climate change.
Continue reading ‘Harpagifer bispinis, but not Patagonotothen tessellata, appears robust to interactive effects of ocean warming and acidification in southern Patagonia’New capability in autonomous ocean carbon observations using the autosub long-range AUV equipped with novel pH and total alkalinity sensors
Published 11 April 2025 Science ClosedTags: chemistry, methods, North Atlantic
The development of marine autonomous platforms has improved our capability to gather ocean observations at fine spatial scales and high temporal frequency, which can be used to better measure, characterize, and model ocean carbon. As part of the OCEANIDS program, novel carbonate sensors were integrated into the Autosub Long-Range (ALR) autonomous underwater vehicle (AUV) and deployed in the Celtic Sea. Autonomous Lab-On-Chip (LOC) sensors measured pH and total alkalinity (TA) while onboard the ALR. Using interpolation, the ALR-sensor data set is compared against CTD co-samples. The average differences between the LOC sensor and co-sample pH range from −0.011 to −0.015. The TA sensor data agrees with co-samples within 1–2 μmol kg–1 on average. Biogeochemical water properties differing between CTD and ALR observations reveal correlations to carbonate parameter variations. The LOC sensors enabled the characterization of the marine carbonate system from autonomous subsurface measurements for the first time. Sensor pH and TA data were used to calculate dissolved inorganic carbon (DIC), partial pressure of CO2 (pCO2), and aragonite saturation state (ΩAr) and are compared with CTD co-samples with mean residuals of 4–7 μmol kg–1, 10–17 μatm, and −0.03 to −0.06, respectively. Future perspectives on sensor deployment and analysis are discussed.
Continue reading ‘New capability in autonomous ocean carbon observations using the autosub long-range AUV equipped with novel pH and total alkalinity sensors’Long-term monitoring of hydrological dynamics and phytoplankton biomass indicator in three shellfish ecosystems of the English Channel (2000-2024)
Published 11 April 2025 Science ClosedTags: biogeochemistry, chemistry, field, North Atlantic
This study investigates the long-term monitoring of physico-chemical parameters and biogeochemical cycles in coastal ecosystems, focusing on three stations in Normandy: Blainville-sur-Mer, Saint-Vaast-la Hougue, and Utah Beach. Over a 24-year period, we analyzed trends in temperature, pH, chlorophyll a concentrations, and nutrient levels, aiming to assess the impacts of climate change and human activities on marine ecosystems. Results show a consistent rise in winter temperatures, particularly since 2013, alongside increasing ocean acidification, especially at Blainville-sur-Mer. These trends suggest potential consequences for planktonic communities and mollusk health. Nutrient analysis revealed significant variations, including high ammonium concentrations on the East coast and a gradual decline in phosphates over the last 15 years, highlighting the influence of anthropogenic activities. The study also identified nutrient limitations, with phosphorus dominating the East coast and nitrogen on the West coast. Our findings emphasize the need for effective nutrient management strategies to mitigate the effects of climate change and human impact, ensuring the sustainability of coastal ecosystems and aquaculture practices. This long-term monitoring is crucial for understanding ecological dynamics and guiding future coastal zone management in the face of global environmental changes.
Continue reading ‘Long-term monitoring of hydrological dynamics and phytoplankton biomass indicator in three shellfish ecosystems of the English Channel (2000-2024)’The impact of ocean acidification on gastropod shell dissolution and microstructure
Published 11 April 2025 Science ClosedTags: biological response, dissolution, growth, laboratory, mollusks, morphology, North Pacific
Highlights
- Ocean acidification causes gastropod shell dissolution and microstructural change.
- Shell growth is inhibited below pH 7.5, with dissolution pits in the inner surface.
- At pH 7.1, shell surface erosion intensifies, with extensive periostracum peeling.
- Shell dissolution negatively correlates with pH, offering a new bio-proxy.
- Shell structural changes can assess past ocean acidification events.
Abstract
Global seawater pH is projected to decrease by 0.3–0.5 units on average by the end of this century, which is considered detrimental to the shells of marine calcareous organisms. However, there is limited understanding of how ocean acidification affects the morphology and structure of these shells, as well as the underlying mechanisms. This study examines the shell growth, surface erosion, and microstructural changes of the marine gastropod Lunella coronata granulata after 85 days of exposure to varying pH (8.1–7.1). The results reveal that at pH ≤ 7.5, shell growth is notably inhibited, with pronounced dissolution hole formation on the inner surface. At pH 7.1, shell surface erosion becomes more pronounced, accompanied by extensive peeling of the shell periostracum. These changes—dissolution hole formation and periostracum peeling—are critical indicators of gastropod shell response to ocean acidification and can serve as biological indicators reflecting current and past ocean acidification. Additionally, our study shows a clear negative correlation between shell dissolution and pH, providing new bio-proxy for indicating the pH changes.
Continue reading ‘The impact of ocean acidification on gastropod shell dissolution and microstructure’Effects of climate change on purple urchin feeding behavior in the presence and absence of California spiny lobsters
Published 11 April 2025 Science ClosedTags: biological response, echinoderms, laboratory, multiple factors, performance, predation, temperature
Grazing by sea urchins can dramatically alter the structure of kelp forest communities, but this can be moderated through both direct and indirect effects from their predators. For example, in southern California, USA, the presence of spiny lobsters, Panulirus interruptus, can dramatically increase the time it takes for purple urchins, Strongylocentrotus purpuratus, to emerge from their shelters to feed, reduce the total time that the urchins spend foraging, and consequently decrease the amount of kelp they consume. The mechanisms driving this, however, may change as the oceans become warmer and more acidic. To examine this, we quantified three measures of purple urchin grazing behavior (latency to emerge from shelters, time spent feeding, and kelp mass consumed) in the presence and absence of spiny lobsters under present day (Current), ocean warming (OW), ocean acidification (OA), and OW + OA (Future) conditions. Specifically, we placed purple urchins in laboratory mesocosms reflecting these conditions with shelters and known quantities of kelp, and then allowed them to graze in both the presence and absence of lobsters for three days. Urchin feeding activity was quantified using time-lapse photography and by recording the amount of kelp eaten over each three-day period. Our results revealed that urchins took longer to emerge from their shelters, grazed for less time, and consumed less kelp when in the presence of spiny lobsters under Current conditions, but these differences largely disappeared under OW, OA and Future conditions. These results reveal possible implications for how urchins will graze when in the presence of predators and thus affect kelp forest communities in the future.
Continue reading ‘Effects of climate change on purple urchin feeding behavior in the presence and absence of California spiny lobsters’Evaluating data quality of coastal spectrophotometric pH measurements: implications for ocean acidification and ocean alkalinity enhancement research
Published 10 April 2025 Science ClosedTags: chemistry, methods
pH, which reflects the thermodynamic balance of acid-base systems in seawater, serves as a key indicator of the interplay between acidic and basic components in marine environments. When combined with another parameter, such as TA, DIC, or pCO2 the entire inorganic carbon system can be derived. However, each parameter presents methodological challenges that may introduce random or systematic errors, which then propagate through subsequent calculations. In coastal and estuarine environments, errors can become more pronounced, as standard operating procedures (SOPs) developed for open-ocean conditions may not adequately address the complexities unique to these regions. Measuring more than two parameters enables further insight into systematic errors through the evaluation of internal consistency, where existing data products often reveal pH-dependent offsets between measured pH and pH calculated from measured TA and DIC. These offsets may arise from errors in pH measurements, TA and DIC measurements, or the equilibrium constants used in the calculations, and are therefore difficult to tease apart. Comparing measurements from different research groups can help identify the specific measurement biases responsible for these offsets; however, the lack of inter-comparison studies, particularly in field settings, hinders our understanding. This work advocates for integrating internal consistency and inter-comparison studies in field conditions, as conducting them at sea provides a realistic evaluation of reproducibility between research groups. Chapter 2 utilizes this method by comparing at-sea spectrophotometric pH (pHspec) measurements from two research groups aboard the R/V Coriolis in June 2022 in the Gulf of St. Lawrence and the Lower St. Lawrence Estuary during the Tracer Release Deep Experiment 2 (TReX2) cruise. This combined analysis of reproducibility and internal consistency highlights how even minor methodological differences can substantially affect data quality, and in turn, shape data interpretation. These impacts are particularly pronounced when estimating potential bias from unidentified, excess components of TA (TAx), expected to be non-negligible in estuarine environments, where the two groups had notably different estimates. Chapter 3 draws conclusions from the discussion of data quality in estuarine environments from Chapter 2, focusing on the potential role of pHspec in Monitoring, Reporting, and Verification (MRV) frameworks for ocean alkalinity enhancement (OAE), a proposed marine carbon dioxide removal (mCDR) strategy. It incorporates insights from OAE field trial work in the Bedford Basin, Halifax, a fjord-like estuarine system, to assess the quality of pHspec, TA, and DIC data, offering an assessment of the reliability of these measurements for interpreting potential carbon dioxide removal. This chapter also includes suggestions for a future protocol for observational components of MRV frameworks.
Continue reading ‘Evaluating data quality of coastal spectrophotometric pH measurements: implications for ocean acidification and ocean alkalinity enhancement research’Biological responses to ocean acidification are changing the global ocean carbon cycle
Published 10 April 2025 Science ClosedTags: chemistry, field, review
Increased oceanic uptake of CO2 due to rising anthropogenic emissions has caused lowered pH levels (ocean acidification) that are hypothesized to diminish biotic calcification and reduce the export of total alkalinity (AT) as carbonate minerals from the surface ocean or their burial in coastal sediments. This “CO2-biotic calcification feedback” is a negative feedback on atmospheric CO2, as elevated levels of surface AT increase the ocean’s capacity to uptake CO2. We detect signatures of this feedback in the global ocean for the first time using repeat hydrographic measurements and seawater property prediction algorithms. Over the course of the past 30 years, we find an increase in global surface AT of 0.072 ± 0.023 μmol kg−1 yr−1, which would have caused approximately 20 Tmol of additional AT to accumulate in the surface ocean. This finding suggests that anthropogenic CO2 emissions are measurably perturbing the cycling of carbon on a planetary scale by disrupting biological patterns. More observations of AT would be required to understand the effects of this feedback on a regional basis and to fully characterize its potential to reduce the efficiency of marine carbon dioxide removal technology.
Key Points
- We find evidence of a long-term trend in alkalinity in the surface ocean using measurements and seawater property prediction algorithms
- We determine this trend is likely driven by the CO2-biotic calcification feedback, a hypothesized negative feedback on atmospheric CO2
- Ocean chemistry is changing globally due to shifting patterns in the ecology of calcifying organisms caused by anthropogenic CO2 emissions
Plain Language Summary
Human activities are causing more carbon dioxide (CO2) to be absorbed by the oceans from the atmosphere, leading to decreasing ocean pH levels (ocean acidification). Acidification slows down biotic calcification, the process by which many marine organisms build their shells and skeletons. Lowered biotic calcification is hypothesized to reduce the carbon moving from the ocean’s surface to the deep when these organisms die and sink. This decrease in the amount of sinking shells leads to a buildup in total alkalinity (AT) in surface waters, which helps the ocean absorb more CO2—a natural feedback mechanism that could limit the rise of atmospheric CO2. We have identified signs of this feedback in the global ocean. Our findings show that the AT in the ocean’s surface is increasing by 0.072 ± 0.023 μmol per kilogram per year, which would have caused the amount of human-emitted carbon in the ocean to increase by about 0.20 PgC since the 1990s. This shows that the chemistry of the oceans is changing as human-produced CO2 emissions cause shifts in the patterns of life and death of some marine organisms. More data on AT is needed to better quantify this feedback and its impacts.
Continue reading ‘Biological responses to ocean acidification are changing the global ocean carbon cycle’Long-term impacts of ocean acidification on the Mediterranean mussel Mytilus galloprovincialis
Published 10 April 2025 Science ClosedTags: biological response, laboratory, Mediterranean, mollusks, mortality, physiology
This study aims to elucidate the long-term physiological impacts of ocean acidification on a key seafood species. The Mediterranean mussel Mytilus galloprovincialis, was subjected to three pH conditions over a period of six months: two pH values within the present range of natural variability (pHT: 8.10 and 7.80) and a lower pH condition (pHT: 7.50) relevant in the context of near-future ocean acidification. A comprehensive assessment was conducted at the conclusion of the fourth and sixth months and encompassed a suite of physiological endpoints, including mortality, oxygen consumption, clearance rate, total haemocyte count (THC), nutritional content analysis, and polonium-210 (210Po) depuration rates. The findings revealed a marked decrease in survival rates at pH 7.50 compared with those at pH 8.10 and 7.80 after six months of exposure. This was associated with a significant increase in THC and a decrease in lipid content. No significant pH effects were observed for other endpoints (namely clearance rate, condition index, oxygen consumption rate, protein and carbohydrate contents, and 210Po). While the lack of response to low pH at some of these physiological endpoints may be a consequence of a lack of statistical power, our data clearly demonstrate the effects of low pH on the survival, THC, and lipid content of M. galloprovincialis. Such effects on a species’ overall fitness have the potential to negatively impact this key seafood species, associated ecosystems, and the socioeconomic dynamics of communities depending on this resource.
Continue reading ‘Long-term impacts of ocean acidification on the Mediterranean mussel Mytilus galloprovincialis’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’Editorial: time-series observations of ocean acidification: a key tool for documenting impacts on a changing planet
Published 10 April 2025 Science ClosedTags: review
Ocean acidification (OA) is a pressing global issue characterized by fundamental changes in ocean chemistry, including the reduction of pH levels, due to the absorption of increased atmospheric CO2. This phenomenon poses significant threats to marine ecosystems, affecting biodiversity, food security, and coastal economies. Time-series observations remain indispensable for documenting these changes, offering insights into the drivers and consequences of OA over temporal and spatial scales. This editorial summarizes the 17 studies in this Research Topic, highlighting the advancements in understanding OA dynamics and their broader implications.
Continue reading ‘Editorial: time-series observations of ocean acidification: a key tool for documenting impacts on a changing planet’Initiation of bivalve shell calcification under ocean acidification: integrating insights from shell to cell
Published 9 April 2025 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, morphology, North Pacific, physiology, reproduction
The formation of initial bivalve shell is sensitive to ocean acidification, encoding the basis of shell formation and environmental information. Here, we demonstrated how the initial shell building processes were affected under various acidified conditions. With decreasing pH, larvae showed smaller shells and higher incidences of deformity. Shell elemental and isotopic profiles suggested that larvae almost exclusively used seawater dissolved inorganic carbon to calcify and exhibited diminished ability to maintain the calcifying fluid homeostasis. Compared to those reared at pHNBS 8.1, larvae exposed at pHNBS 7.7 downregulated the expression of genes related to transport of calcification substrates and regulation of carbonate chemistry, all of which were subsequently upregulated at pHNBS 7.4. This integrated finding advances the application of sclerochronology by providing insights into the initial shell formation, a crucial phase that is overlooked in sclerochronological studies, particularly in how environmental stressors affect the interpretation of geochemical proxies in adult shells.
Continue reading ‘Initiation of bivalve shell calcification under ocean acidification: integrating insights from shell to cell’Warmer oceans, acidification endanger Sri Lanka’s maritime heritage
Published 8 April 2025 Media coverage ClosedTags: Indian
Sri Lanka’s waters are home to over 200 shipwrecks, each holding a unique story of trade, war, and maritime heritage. Among the most significant are the Godawaya Shipwreck, which dates back over 2,000 years, and HMS Hermes, the world’s first purpose-built aircraft carrier built by British and sunk by Japanese dive bombers during World War II (1931-1945).
Over time, these shipwrecks have transformed into artificial reefs, supporting marine biodiversity and playing a crucial role in ocean ecosystems. However, climate change is now emerging as a major threat to their survival, potentially shortening their lifespan.
“Shipwrecks face multiple threats from climate change,” says Prof. Sevvandi Jayakody of the Department of Aquaculture and Fisheries at Wayamba University of Sri Lanka. “These include extreme weather events, ocean acidification, invasive species, and rising sea temperatures, all of which can accelerate the degradation of wrecks.”
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Human-induced climate change, driven by greenhouse gas emissions such as carbon dioxide (CO₂), not only warms the planet but also increases ocean acidity when the ocean absorbs carbon dioxide from the atmosphere, which lowers the ocean’s pH.
“Globally, research has shown that ocean acidification speeds up the corrosion rate of iron and steel wrecks,” notes Prof. Jayakody. “This is especially concerning for wrecks like HMS Hermes, which may still contain live ammunition. As the metal weakens, there is a risk of explosive materials being exposed.”
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Although ocean acidification studies in Sri Lanka are still in their early stages, the National Aquatic Resources Research and Development Agency (NARA) is monitoring pH levels in coastal waters.
“We take regular measurements from stations on both the east and west coasts,” says Dr. Kanapathipillai Arulananthan director general of NARA. “Additionally, the Norwegian research vessel Nansen is expected to provide further insights into changing ocean parameters in the Northern Indian Ocean.”
Another hidden threat is the rise of invasive species that could now establish in different areas due to warming waters. Changes in ocean temperature and acidity alter microbial activity, leads to faster decomposition of wooden shipwrecks according to research.
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Ballast water from ships can introduce these invasive species to new environments. While differences in salinity, temperature, and acidity once prevented their survival, climate change is making new habitats more suitable for these species, increasing the risk of bioerosion.
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As climate change intensifies, Sri Lanka’s shipwrecks face an uncertain future. Without proactive measures, these historical and ecological treasures could deteriorate beyond recognition, taking with them invaluable insights into the past —and a crucial refuge for marine life in the present.
Mr. Mutukumarana said every shipwreck is unique and when one disintegrates so goes its story, too. The only way forward would be to reduce the rate of global warming.
Continue reading ‘Warmer oceans, acidification endanger Sri Lanka’s maritime heritage’The many pathways of climate change affecting coastal ecosystems: a case study of western Vancouver Island, Canada
Published 7 April 2025 Science ClosedTags: biological response, multiple factors, North Pacific, review, temperature
Climate change threatens marine ecosystems with known effects on marine life, including changes in metabolic rates, survival, and community structure. Based on a structured literature review, we developed a conceptual “pathways of effects” model that summarizes how three stressors associated with climate change (warming, acidification, and storms) affect functional species groups on the West Coast of Vancouver Island, Canada. We identified 155 distinct pathways from the three stressors through 12 categories of biological effects ranging from changes in the biochemistry of individual organisms to effects on community composition. Most species groups were affected by several climate stressors and via many pathways, although individual studies generally considered only a small fraction of relevant pathways. These effects depended on the species of interest and geographical location, highlighting the importance of local research. Climate change stressors exert complex, sometimes contradictory effects that vary across ecological scales. For example, some stressors that adversely affected a species in laboratory studies appeared beneficial in community-scale field studies. Pathways of effects models are helpful tools to summarize scientific studies across ecological scales. Compiling them in standardized databases would allow researchers and practitioners to search across species and regions to better support ecosystem-based management and environmental impact assessment.
Continue reading ‘The many pathways of climate change affecting coastal ecosystems: a case study of western Vancouver Island, Canada’Ocean acidification disrupts the energy balance and impairs the health of mussels (Mytilus coruscus) by weakening their trophic interactions with microalgae and intestinal microbiome
Published 4 April 2025 Science ClosedTags: biological response, BRcommunity, community composition, laboratory, mollusks, North Pacific, otherprocess, performance, physiology, phytoplankton, prokaryotes
Highlights
- Ocean acidification disrupts mussel energy balance by weakening trophic interactions.
- Mussels exposed to acidified conditions show reduced energy gain from microalgae.
- Energy imbalance caused by acidification impairs mussel health and fitness.
- Ocean acidification can threaten mussel farming and marine ecosystem stability.
Abstract
Despite extensive research in the last two decades, exploring the potential mechanisms underlying the sensitivity and resistance of marine organisms to ocean acidification is still imperative. Species interactions can play a role in these mechanisms, but the extent to which they modulate organismal responses to ocean acidification remains largely unknown. Here, we investigated how ocean acidification (pH 7.7) affects energy homeostasis and fitness of mussels (Mytilus coruscus) by assessing their physiological responses, intestinal microbiome and nutritional quality of their food (microalgae). Under ocean acidification, the mussels had reduced feeding rates by 34 % and reduced activities of digestive enzymes (pepsin by 39 %, trypsin by 28 % and lipase by 53 %) due to direct exposure to acidified seawater and increased phenol content of microalgae. Richness and diversity of intestinal microbiome (OTU, Chao1 index and Shannon index) were also lowered by ocean acidification, which can undermine nutrient absorption. On the other hand, energy expenditure of mussels increased by 53 % under ocean acidification, which was associated with the upregulation of antioxidant defence (SOD, CAT and GPx activities). Consequently, energy reserves in mussels decreased by 28 %, which were underpinned by the reduction in protein, carbohydrate and lipid contents. Overall, we demonstrate that ocean acidification could disrupt herbivore-algae and host-microbe interactions, thereby lowering the energy balance and impairing the health of marine organisms. This can have ramifications on the population and energy dynamics of marine communities in the acidifying ocean.
Continue reading ‘Ocean acidification disrupts the energy balance and impairs the health of mussels (Mytilus coruscus) by weakening their trophic interactions with microalgae and intestinal microbiome’An updated version of the OA-ICC bibliographic database is available online.
The database currently contains 9314 references and includes citations, abstracts and assigned keywords. Updates are made every month.
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Continue reading ‘OA-ICC bibliographic database updated’Chapter 6 – Ocean warming, acidification, plastic pollution, and water quality deterioration: a multifaceted crisis unveiled
Published 2 April 2025 Science ClosedTags: mitigation, review
The Earth’s oceans, vast and enigmatic, have long captivated human imaginations with their depths teeming with life. Since the Industrial Revolution, anthropogenic impacts on natural systems have constantly intensified, especially on marine systems. Although most stressors have an anthropogenic origin and occur worldwide, they present different characteristics on which they may be managed. Yet, beneath ocean surfaces lies a profound and intricate crisis – a convergence of challenges that threaten all biological realms and associated marine and coastal environments. This chapter embarks on the intensities and effects of ocean warming, acidification, and plastic pollution-induced water quality deterioration, revealing their interconnectedness and underscoring the urgency of our response. Due to increasing atmospheric CO2, the world’s oceans are warming and slowly becoming more acidic (ocean acidification), and profound changes in marine ecosystems are certain. Calcification is one of the primary targets for studies of the impact of CO2-driven climate change in the oceans. Plastic pollution is ubiquitous in the ocean but causes the most serious harm near coastlines and during its journey toward open waters. The formation of oxygen-depleted dead zones and toxic algal blooms narrate the threats of a compromised aquatic realm due to ocean water quality deterioration. Managing waste and litter streams better, eliminating unnecessary products, ensuring adequate waste management systems are in place, setting up a circular economy for plastic products and waste where possible, boosting recycling, and incinerating unrecyclable plastic waste for energy in conjunction with the development of carbon capture and storage technology help balancing the trade-off with greenhouse gas emissions. Ocean-based renewable energy sources like wave and tidal power can reduce greenhouse gas emissions, combating ocean warming. Carbon capture and storage systems can alleviate acidification by capturing CO 2 emissions from various sources. Advanced waste-removal technologies, including ocean cleanup vessels and AI-powered monitoring systems, aid in tackling plastic pollution. More stress ecology research is needed at the frontier between ecotoxicology and ecology, going beyond standardized tests using model marine species to address multiple water quality factors (pH, temperature, toxicants, etc.) and organisms’ health. These technologies, combined with global collaborations, blue economic strategies, and building awareness, can play a pivotal role in preserving the health and sustainability of Earth’s oceans.
Continue reading ‘Chapter 6 – Ocean warming, acidification, plastic pollution, and water quality deterioration: a multifaceted crisis unveiled’
