Ocean acidification is posing a threat to marine bivalve species who struggle to deposit calcium carbonate in order to grow their shell. Some oyster species have developed a brooding reproductive strategy which might help them cope with this acidification stress. Brooding oysters have shown to be more resilient against ocean acidification than broadcast spawning oyster species. It is suspected that because the brood chamber is on top of the maternal gills, the mothers add carbon dioxide into the chamber from her respiration. This suggests larvae evolved to develop in a more acidic environment than the surrounding water column. Through exaptation the larvae may have coopted traits needed for development in the brood chamber which now enable them to be more resilient to ocean acidification. In this study, we measured the pH inside the brood chamber of Ostrea edulis under current and future predicted ocean conditions (i.e., elevated temperature and decreased seawater pH) to get a better understanding of the ambient-maternal relationship on brood chamber pH fluctuations under ocean acidification scenarios. The results suggested that maternal respiration indeed makes the brood chamber always a more acidified environment then the surrounding water. Elevated temperatures in the surrounding water slightly lower the pH as a result of increased maternal metabolism. Yet lowering the ambient pH causes a much larger and significant reduction of internal pH levels since the oyster is constantly filtering the overlaying water while the valves open. Additionally, there seems to be a positive relationship between shell gape and internal pH changes suggesting that the mothers behaviour may also influence how fast and to which level pH values can drop inside the brood chamber. These results give an indication of what conditions brooding oysters larvae will have to face in the future and helps determine possible winners and beneficial strategies in an acidified ocean.
Continue reading ‘Dynamics in brood chamber pH of the European flat oyster (Ostrea edulis) in response to ocean acidification’Archive Page 49
Dynamics in brood chamber pH of the European flat oyster (Ostrea edulis) in response to ocean acidification
Published 13 February 2025 Science ClosedTags: biological response, laboratory, mollusks, multiple factors, North Atlantic, performance, physiology, temperature
Earth’s acid test: When did ocean acidity allow life to commence?
Published 13 February 2025 Press releases ClosedScientists at Yale and in Singapore have devised what may be the ultimate acid test — a comprehensive model for estimating the origins of Earth’s habitability, based in part on ocean acidity.
The new theoretical model applies previously published, Yale-led research to a wide range of interconnected geological and atmospheric processes. It may provide the clearest picture yet of how Earth evolved to a point where life was able to flourish.
“This is a tour-de-force theoretical endeavor, bridging a longstanding gap between surface processes and processes deep in the Earth,” said Jun Korenaga, a professor of Earth and planetary sciences in Yale’s Faculty of Arts and Sciences, and co-author of a new study in the journal Nature Geoscience. “This work presents by far the most comprehensive whole-Earth system model to estimate how ocean pH likely evolved during Earth’s history.”
The term pH (“potential of hydrogen”) is a measure of the concentration of hydrogen ions in an aqueous — watery — solution. A lower pH level equals higher acidity. A solution with a pH lower than 7 is considered acidic; modern-day seawater has a pH of about 8.
But it is widely believed that Earth’s ancient ocean was much more acidic, making it harder to sustain life. Many scientists have found that the synthesis of organic molecules is extremely difficult in environments with a pH level lower than 7.
Continue reading ‘Earth’s acid test: When did ocean acidity allow life to commence?’Rapid rise of early ocean pH under elevated weathering rates
Published 13 February 2025 Science ClosedTags: chemistry, globalmodeling, modeling
Ocean pH is a fundamental property regulating various aspects of Earth system evolution. However, early ocean pH remains controversial, with estimates ranging from strongly acidic to alkaline. Here we develop a model integrating global carbon cycling with ocean geochemistry, and incorporating continental growth and mantle thermal evolution. By coupling global carbon cycle with ocean charge balance, and by using solid Earth processes of mantle degassing and crustal evolution to specify the history of volatile distribution and ocean chemistry, we show that a rapid increase in ocean pH is likely during the Hadean to the early Archaean eons, with pH evolving from 5 to neutral by approximately 4.0 Gyr ago. This rapid pH evolution is attributed primarily to elevated rates of both seafloor and continental weathering during the Hadean. This acceleration in weathering rates originates in the unique aspects of Hadean geodynamics, including rapid crust formation, different crustal lithology and fast plate motion. Earth probably transformed from a hostile state to a habitable one by the end of the Hadean, approximately 4.0 Gyr ago, with important implications for planetary habitability and the origin of life.
Continue reading ‘Rapid rise of early ocean pH under elevated weathering rates’Future actions for the ocean acidification research community to support marine industries and coastal communities of Aotearoa New Zealand
Published 12 February 2025 Science ClosedTags: fisheries, mitigation, policy
Increasing atmospheric CO2 emissions are altering the carbonate chemistry of seawater in a process known as ocean acidification (OA). This is a growing issue for marine industries and communities. During the 2023 New Zealand Ocean Acidification Community (NZOAC) Conference, the community undertook a horizon scanning exercise to determine potential future activities and opportunities. Conference participants were sent questions that focussed on topics of importance to the Aotearoa New Zealand and global OA community. Sixteen potential actions were identified. During the conference, participants voted for actions they perceived to be most important to give each an overall priority score. In order, the five top priority actions were to (i) re-engage with policymakers to ensure OA is included in policies around climate change, oceans, fisheries, and education; (ii) focus on solutions during engagement actions; (iii) maintain funding for current observation platforms; (iv) engage more with the public through community/public participatory science; and (v) obtain funding for new OA focused research. We summarise the activities identified to address these actions and discuss potential ways forward for the NZOAC and wider research community to undertake the required research and provide much needed guidance to underpin OA mitigation and adaptation efforts.
Continue reading ‘Future actions for the ocean acidification research community to support marine industries and coastal communities of Aotearoa New Zealand’The effects of combined stress from pH and microplastic-derived odours on the European green crab Carcinus maenas’s olfactory behaviour
Published 12 February 2025 Science ClosedTags: biological response, crustaceans, laboratory, North Atlantic, performance
Simple Summary
The European shore crab, Carcinus maenas, also known as the European green crab, uses its sense of smell to detect prey, predators, and mating partners. Here, we examined how such crabs behave in environmental conditions that simulate the changes predicted by climate change. Crabs were exposed to female sexual odours, food smells, and various types of plastic leach outs. A decreased pH altered the crab’s behaviour towards food (Glutathione) and sex odour, reducing the animal’s response levels and increasing reaction times. Most interestingly, the crabs were more attracted to polyethylene (PE) odour in future ocean conditions, whilst males’ responses to female sex cues were especially reduced significantly. Response-level changes vary between the sexes, highlighting that understanding the effects of climate conditions on animal behaviour and choices is complicated and difficult to predict. That crabs become more attracted to plastic raises the question of what the bioactive chemicals are in PE that induce such a response, and this could demonstrate how climate change potentially increases the risks associated with plastic pollution in future oceans.
Abstract
Ocean acidification (OA) associated with climate change is expected to lower the ocean’s pH by 0.5 units by 2100. Whilst associated effects such as coral bleaching and shell calcification are well documented, lesser-known impacts are the ‘invisible’ effects on animal sensory systems. Olfactory disruption impacts the behaviour towards chemical cues in many marine species, including crustaceans. We examine the effects of microplastic odour and additional stressors on the European green crab C. maenas. Using uridine diphosphate (UDP) and uridine triphosphate (UTP) as a sex pheromone bouquet, glutathione (GSH) as a food cue, and polyethylene (PE) as plastic odour, cues were mixed with carboxycellulose to create slow-release gels. Crabs were exposed to gels in seawater pH values of 8.2, 7.6, and 7.2. Crabs took longer to react to all odours in reduced pH conditions (pH 8.2 to pH 7.2, p = 0.0017). At a low pH, PE-exposed crabs exhibited attraction towards microplastic odour and changed behavioural responses by burying. The study confirms low pH as disruptive to olfaction and highlights that plastic derivatives can become more bioactive at reduced pH levels, potentially increasing the threat posed by microplastic pollution. Further research is required to determine the potential long-term impacts of the combined threat of microplastics and reduced pH in the environment.
Continue reading ‘The effects of combined stress from pH and microplastic-derived odours on the European green crab Carcinus maenas’s olfactory behaviour’Long-term variations in pH in coastal waters along the Korean Peninsula
Published 12 February 2025 Science ClosedTags: biogeochemistry, chemistry, field, North Pacific
Declining seawater pH, associated with rising atmospheric CO2 levels, adversely affects marine organisms and ecosystems, thereby posing a considerable risk to coastal fisheries and economies. However, the effects of long-term pH variations in coastal waters remain poorly understood. In this study, we investigated the variability in pH in the coastal waters of Korea over an 11-year period (2010–2020) and sought to identify the principal drivers of pH fluctuations. Unlike the persistent pH declines observed in the open oceans and other coastal systems, Korean coastal waters showed no persistent pH variation, thus indicating that local biogeochemical processes may have a greater influence than atmospheric CO2 in determining aquatic pH. Analysis of environmental data including temperature, salinity, chlorophyll a, and dissolved oxygen (DO) revealed a strong correlation between pH and DO. However, instances of pH changes exceeding those predicted by DO depletion alone indicate the influence of additional biogeochemical factors. As global seawaters warm, reduction in DO is anticipated to cause a further decline in the pH of coastal waters. This trend could have a pronounced influence on Korean coastal waters, which support extensive aquaculture operations integral to the local and national economies. Consequently, high-frequency monitoring is essential for extending the current time series and predicting future water quality.
Continue reading ‘Long-term variations in pH in coastal waters along the Korean Peninsula’Interactive effects of multiple stressors in coastal ecosystems
Published 12 February 2025 Science ClosedTags: biological response, multiple factors, review
Coastal ecosystems are increasingly experiencing anthropogenic pressures such as climate warming, CO2 increase, metal and organic pollution, overfishing, and resource extraction. Some resulting stressors are more direct like pollution and fisheries, and others more indirect like ocean acidification, yet they jointly affect marine biota, communities, and entire ecosystems. While single-stressor effects have been widely investigated, the interactive effects of multiple stressors on ecosystems are less researched. In this study, we review the literature on multiple stressors and their interactive effects in coastal environments across organisms. We classify the interactions into three categories: synergistic, additive, and antagonistic. We found phytoplankton and bivalves to be the most studied taxonomic groups. Climate warming is identified as the most dominant stressor which, in combination, with other stressors such as ocean acidification, eutrophication, and metal pollution exacerbate adverse effects on physiological traits such as growth rate, fitness, basal respiration, and size. Phytoplankton appears to be most sensitive to interactions between warming, metal and nutrient pollution. In warm and nutrient-enriched environments, the presence of metals considerably affects the uptake of nutrients, and increases respiration costs and toxin production in phytoplankton. For bivalves, warming and low pH are the most lethal stressors. The combined effect of heat stress and ocean acidification leads to decreased growth rate, shell size, and acid-base regulation capacity in bivalves. However, for a holistic understanding of how coastal food webs will evolve with ongoing changes, we suggest more research on ecosystem-level responses. This can be achieved by combining in-situ observations from controlled environments (e.g. mesocosm experiments) with modelling approaches.
Continue reading ‘Interactive effects of multiple stressors in coastal ecosystems’Behavioral and physiological effects of ocean acidification on juvenile American lobsters (Homarus americanus)
Published 12 February 2025 Science ClosedTags: biological response, crustaceans, laboratory, North Atlantic, performance, physiology
Alteration of pH within the world’s ocean, or ocean acidification (OA), results from increased absorption of CO2 into global waters. Acidification can positively or negatively affect physiology and behavior of marine taxa, though the effects vary greatly based on species and life stage. Crustaceans are often noted as being resilient to acidification, though negative physiological and behavioral impacts have been shown. Studies on the impacts of OA on the American lobster (Homarus americanus) have primarily focused on its physiology. This thesis aims to observe the potential effects of acidification on the foraging behavior and hemolymph chemistry of juvenile American lobsters. We exposed 28 juvenile lobsters (carapace length, CL, 29mm – 52mm, average 42 +/- 1.3mm) to randomly assigned, individual pH values between 7.3 and 7.8 for 12 days to observe potential impacts of acidification. The time taken to locate blue mussels, the number of foraging trips taken, the time taken to successfully feed, and hemolymph L-lactate concentration (stress indicator) were assessed after the exposure period. Counter to our predictions, as pH decreased, lobsters successfully fed two-times quicker, maintained normal locate times of prey, and took fewer foraging trips. We found that lobsters responsed to prey cues similarly across the pH range, indicating that olfaction was likely not impaired. These results suggest that juvenile American lobsters may increase foraging activity in response to acidified conditions.
Continue reading ‘Behavioral and physiological effects of ocean acidification on juvenile American lobsters (Homarus americanus)’Global environmental change mediated response of wetland plants: evidence from past decades
Published 11 February 2025 Science ClosedTags: biological response, chemistry, phanerogams, review
Highlights
- Wetland plant research on climate change responses showed an upward trend.
- Plant growth affected negatively by increase in CO2, temperature and sea level.
- Extreme weather events harmed wetland plant landscapes.
- Collaborative research is needed for sustainability of wetland plants
Abstract
Wetland ecosystems are critically affected by global environmental changes, yet understanding the impact of these changes on wetland plants remains a challenge. This review article employs a comprehensive approach, including bibliographic analysis, utilization of various climate models for historical data retrieval, and extensive literature survey, to investigate the response of wetland plants to environmental shifts over the past decades. The analysis conducted in this study uncovers a multitude of climatic parameters that exhibit an influence on the dynamics of wetland vegetation. Results indicated a significant positive trend in atmospheric CO2 concentration, leading to increased water use efficiency in some plant species, particularly C3 plants. However, C4 plants did not show the same positive response. Nitrous oxide growth rate showed a weaker, less consistent trend than CO2, highlighting the need for further investigation into the complex factors influencing Nitrous oxide emissions from wetlands. Methane growth rate and global mean sea level demonstrated a strong positive linear trend. Ocean pH exhibited a statistically significant downward trend (acidification), while sea surface temperature showed a moderate but statistically significant upward trend. Glacier mass balance revealed a significant negative trend. Although some plants may benefit from increased CO2 initially, but the combined effects of rising sea levels, ocean acidification, and temperature changes pose substantial threats to the overall health and diversity of wetland plant life.
Continue reading ‘Global environmental change mediated response of wetland plants: evidence from past decades’The effect of carbonate mineral additions on biogeochemical conditions in surface sediments and benthic–pelagic exchange fluxes (update)
Published 11 February 2025 Science ClosedTags: biogeochemistry, chemistry, dissolution, mitigation, modeling, regionalmodeling, sediment
Coastal sediments are hotspots of biogeochemical processes that are impacting subsurface and overlying water conditions. Fluid composition in sediments is altered through the mineralization of organic matter which, under oxic conditions, further lowers both pH and the carbonate saturation state. As a potential mitigation strategy for this sediment acidification, we explored the effects of mineral additions to coastal sediments. We experimentally quantified carbonate mineral dissolution kinetics of carbonate shells suitable for field application and then integrated these data into a reactive transport model that represents early diagenetic cycling of C, O, N, S, and Fe and traces total alkalinity, pH, and saturation state of CaCO3. Model simulations were carried out to delineate the impact of mineral type and amount added, porewater mixing, and organic matter mineralization rates on sediment alkalinity and its flux to the overlying water. Model results showed that the added minerals undergo initial rapid dissolution and generate saturated conditions demonstrating the potential of alkalinity enhancement in mitigating surface sediment acidification. Aragonite dissolution led to higher total alkalinity concentrations than calcite. Simulations of carbonate mineral additions to sediment environments with low rates of organic matter mineralization exhibited a substantial increase in mineral saturation state compared to sediments with high CO2 production rates, highlighting the environment-specific extent of the effect of mineral addition. Our work indicates that carbonate additions have the potential to effectively buffer surficial sediments over multiple years, yielding biogeochemical conditions that counteract the detrimental effect of low-pH sediment conditions on larval recruitment and potentially increase benthic alkalinity fluxes to support marine carbon dioxide removal (mCDR) in the overlying water.
Continue reading ‘The effect of carbonate mineral additions on biogeochemical conditions in surface sediments and benthic–pelagic exchange fluxes (update)’Innovations in ocean biogeochemical instrumentation and monitoring
Published 11 February 2025 Science ClosedTags: biogeochemistry, chemistry, field, methods
Anthropogenic activities are driving changes in ocean biogeochemistry, which can be monitored through instruments and sensors deployed across diverse platforms in even the harshest marine environments. Continued monitoring of these changes demands innovations in instrumentation, calibration and quality control to effectively capture dynamic signals and ensure comprehensive ocean coverage. This dissertation focuses on advancements in oceanographic pH sensors, starting with the longest near-continuous ocean pH dataset collected using ionsensitive field effect transistor (ISFET) technology at Scripps Pier. A new in situ calibration approach, based on direct tris buffer injection, was compared to the traditional bottle collection method, yielding a fourfold improvement in repeatability with an uncertainty of 0.006 pH. Additionally, an automated calibration system integrated into the sensor package was evaluated, offering near real-time, self-calibrating capability for ocean acidification and biogeochemical monitoring programs. To continue the discourse of pH sensor technology in the second section of this dissertation, a novel optical pH sensor was evaluated in laboratory settings to establish its accuracy and precision, response time, temperature and pressure sensitivity, and calibration techniques which improved accuracy over factory methods. Field tests of the optical pH sensor across diverse marine environments—deep ocean, dynamic nearshore, and open ocean profiling—provided guidelines for field calibration, correction and optimal field use. In a scaled-up sense, the final section of this dissertation leveraged pH and other biogeochemical sensors on BGC-Argo profiling floats to explore biogeochemical variability in the equatorial Pacific from 2019 to 2024. While the region has extensive physical data, subsurface biogeochemical observations and their links to El Niño and La Niña cycles are sparse. These floats revealed distinct biogeochemical patterns driven by vertical movement of the mixed layer depth, meridional subtropical water transport and primary production shifts associated with ENSO phases. Overall, this work combines new sensor technologies and analytical methods to provide essential data, instrument guidelines and reveal insights into ocean biogeochemical phenomena. Ongoing instrumentation development and monitoring will be critical to expand and deepen our understanding of how human-driven impacts are transforming our oceans.
Continue reading ‘Innovations in ocean biogeochemical instrumentation and monitoring’Variability in storm season intensity modulates ocean acidification conditions in the northern Strait of Georgia
Published 11 February 2025 Science ClosedTags: chemistry, field, North Pacific
Large changes in marine CO2 chemistry manifest in areas with weakly-buffered seawater where ocean acidification (OA) acts in concert with natural CO2 additions. These settings can exhibit periods of extreme OA in the form of multiple co-occurring stressors, including calcite undersaturation and low pH. Such conditions were observed in the northern Strait of Georgia, on the northeast Pacific coast, where extreme OA spanned a 3-year period. Here, we utilized an 8-year, highly-resolved record of seawater CO2 partial pressure and total dissolved inorganic carbon to decompose the drivers of this extreme OA. We find that variability in storm season intensity shaped the extent of conservative mixing and biogeochemical drivers such that manifests of extreme OA arise in this setting. Extreme OA manifested during years with weak storm seasons due to direct and indirect biogeochemical factors and the reduced impact of conservative mixing. This sensitivity to the storm season intensity highlights how vulnerable the northern Strait of Georgia is to subtle changes in environmental forcing and provides some predictive capacity for OA conditions over the coming year. These results illustrate that OA is not a “slow burn” process within weakly-buffered settings, but rather invokes periods of intensification with poorly understood biological implications.
Continue reading ‘Variability in storm season intensity modulates ocean acidification conditions in the northern Strait of Georgia’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’CO2 fertilisation counteracts the negative effect of poor water quality on the growth and photosynthesis of a Great Barrier Reef coralline alga
Published 10 February 2025 Science ClosedTags: algae, biological response, growth, laboratory, light, multiple factors, nutrients, photosynthesis, physiology
The global problem of ocean acidification and localised decline in water quality are major threats to coral reefs worldwide. This study examined the individual and interactive impacts of global and local stressors by investigating the effects of increased seawater pCO2, elevated nutrient concentrations and reduced light levels on linear growth and metabolic rates of the common branching crustose coralline alga Lithophyllum cf. pygmaeum. We found complex interactions between factors on algal growth and photosynthetic rates, but overall, growth was significantly enhanced by pCO2 enrichment under all light and nutrient combinations. This is the first study to report a positive growth response in coralline algae to elevated pCO2 using linear extension methods. In contrast, the combination of reduced light levels and high nutrient concentrations simulating poor water quality conditions reduced algal growth rates by up to 67% (compared to individuals exposed to high light, low nutrients and elevated pCO2). Decreased light levels reduced linear growth, Pgross and Pnet rates by 33%, 18% and 24%, respectively, highlighting the critical role of light in coralline algal physiology. We suggest that poor water quality may counteract any CO2 fertilisation effect under ocean acidification conditions on the growth of coralline algae, and this has implications for coral reef conservation as it emphasises the importance of improving water quality to maintaining coral reef functions. These results further highlight the need for multifactorial experiments to better understand the interplay between global and local processes on coralline algae growth.
Continue reading ‘CO2 fertilisation counteracts the negative effect of poor water quality on the growth and photosynthesis of a Great Barrier Reef coralline alga’Olfactory specialization in the Senegalese sole (Solea senegalensis): CO2 acidified water triggers nostril-specific immune processes
Published 10 February 2025 Science ClosedTags: biological response, fish, laboratory, molecular biology, morphology, North Atlantic, physiology
Highlights
- Exposure to high PCO2/low pH water decreases olfactory sensitivity in sole more markedly in the upper olfactory epithelium (OE).
- Resilience of the lower OE may be linked to exposure to a different environment.
- Regulation of genes related to neuromodulation and neuroplasticity suggests activation of compensatory mechanisms.
- Regulation of immune processes related genes together with histological modifications will likely compromise olfactory sensitivity with behavioural consequences.
- Ocean acidification has effects on the peripheral nervous system at various levels.
Abstract
Increased carbon dioxide (CO2) in the ocean is changing seawater chemistry. Behavioural alterations in CO2 exposed fish have been linked to changes in the central nervous system (CNS). However, we hypothesise that receptor cells in direct contact with the environment are more susceptible to changes in water chemistry than the CNS. Electrophysiology, histology, and transcriptomics were used to explore the effect of exposure to CO2 acidified water on the olfactory epithelium (OE) of the Senegalese sole (Solea senegalensis). The upper and lower OE of this flatfish detect different odorants and are in contact with different environments. Acute exposure to acidified water decreased olfactory sensitivity more in the upper than in the lower OE. After chronic exposure to high CO2 there was no histological changes in the upper OE, however, in the lower OE, there was a massive infiltration of melanomacrophage (MMC) and tissue disorganization. In addition, in the upper OE, differential expressed gene transcripts (DETs) were related to inflammation and innate immune processes whereas in the lower OE, DETs were related to the adaptative immune response. Differential regulation of genes related to neurogenesis and plasticity occurred in both epithelia.
The effects of ocean acidification in sole OE depends on the nostril, however the occurrence of an exacerbated immune response, OE remodelling and reduced sensitivity indicate that ocean acidification is likely to have significant and unpredictable consequences for behaviour.
Continue reading ‘Olfactory specialization in the Senegalese sole (Solea senegalensis): CO2 acidified water triggers nostril-specific immune processes’La información sobre acidificación del océano podría influir en decisión de compra de mariscos (in spanish)
Published 10 February 2025 Press releases ClosedEl Cambio Global ha generado múltiples impactos en los ecosistemas marinos, desde la elevación del nivel del mar, hasta el aumento en la frecuencia de eventos climáticos extremos. Sin embargo, entre ellos la acidificación del océano (AO) sigue siendo un fenómeno poco comprendido a pesar de sus graves consecuencias para los ecosistemas y recursos marinos. Producida por la absorción de dióxido de carbono generado por actividades humanas, la AO altera la química del agua, dificultando la formación de conchas y estructuras calcáreas en muchas especies marinas, afectando directamente la acuicultura. En particular a bivalvos como choritos y ostiones, que podrían ver comprometida su calidad comercial debido a cambios en su color, tamaño, textura y valor nutricional, entre otros atributos.
Frente a esta problemática, un equipo de investigadores del Instituto Milenio en Socio-Ecología Costera (SECOS), la U. Católica de la Santísima Concepción, la Universidad del Desarrollo, y el Centro de Ecología Aplicada y Sustentabilidad (CAPES), entre otras instituciones, llevó a cabo un estudio publicado en la revista Future Foods. Utilizando técnicas de Preferencias Declaradas, los investigadores diseñaron un experimento para evaluar cómo la entrega de información sobre la AO podría influir en las decisiones de compra de los consumidores.
El estudio reveló que los consumidores prefieren productos con una “buena apariencia”, caracterizada por un color uniforme, ausencia de epibiontes [ciertos organismos pegados a la concha] y sin quiebres en la concha. Además, valoran la composición nutricional al momento de tomar una decisión de compra. “Justamente este es un atributo que será modificado por el cambio global, donde hemos observado una disminución en ácidos grasos, minerales, proteínas y vitaminas”, señala Valeska San Martín, investigadora del Centro de Investigaciones Costeras de la U. de Atacama y también del SECOS. La investigación además indicó que, cuando los consumidores reciben información sobre la AO, tienden a elegir el “mejor producto” disponible en el mercado, influenciados por factores como calidad, conveniencia personal y valor.
Continue reading ‘La información sobre acidificación del océano podría influir en decisión de compra de mariscos (in spanish)’Effect of seawater acidification on energy metabolism in the hydrocoral Millepora alcicornis: inhibition of citrate synthase activity indicates disruption in aerobic pathways
Published 10 February 2025 Science ClosedTags: biological response, cnidaria, laboratory, mesocosms, physiology, South Atlantic
Ocean acidification is a major threat to coral reefs worldwide, with reduced growth already reported in the hydrocoral Millepora alcicornis (Linnaeus, 1758) under these conditions. Inhibition of enzymes related to energy metabolism is hypothesized as one of the mechanisms associated with the physiological impacts of ocean acidification. Therefore, a mesocosm experiment was conducted to investigate whether three levels of decreasing seawater pH could alter the activity of key enzymes involved in the energy metabolism in M. alcicornis. Hydrocorals were acclimated to marine mesocosm conditions for 20 days and then exposed to different seawater pH levels [ambient pH (8.1) and experimental pH (7.8, 7.5 and 7.2)] for 16 and 30 days. Endpoints analyzed included the activity of key enzymes involved in the regulation of the glycolytic pathway (hexokinase and pyruvate kinase), aerobic energy production via the Krebs cycle (citrate synthase) and anaerobic energy production via lactate formation (lactate dehydrogenase). The results obtained show that only citrate synthase was affected by seawater acidification, as a marked reduction in its activity was observed at all experimental pH levels tested (7.8, 7.5 and 7.2). This finding indicates that reduced growth previously reported for M. alcicornis under seawater acidification conditions can be explained, at least in part, by a negative impact on the Krebs cycle, a major pathway involved in aerobic energy production.
Continue reading ‘Effect of seawater acidification on energy metabolism in the hydrocoral Millepora alcicornis: inhibition of citrate synthase activity indicates disruption in aerobic pathways’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’Short-term negative effects of seawater acidification on the rhodolith holobionts metatranscriptome
Published 7 February 2025 Science ClosedTags: algae, biological response, BRcommunity, community composition, laboratory, molecular biology, otherprocess, prokaryotes, South Atlantic
Highlights
- Cyanobacteria dominate the microbial community in living rhodoliths.
- Vibrionales dominate dead rhodolith skeletons.
- Short-term (1 h) acidification affects the microbial community structure.
- Diverse functional genes modulate microbe-host interactions.
Abstract
Rhodolith holobionts are formed by calcareous coralline algae (e.g., Corallinales) and associated microbiomes. The largest rhodolith bank in the South Atlantic is located in the Abrolhos Bank, in southwestern Brazil, covering an area of 22,000 km2. Rhodoliths serve as nurseries for marine life. However, ocean acidification threatens them with extinction. The acute effects of high pCO₂ levels on rhodolith metatranscriptomes remain unknown. This study investigates the transcriptomic profiles of rhodoliths exposed to short-term (96-h) high pCO₂ levels (up to 1638 ppm). Metatranscriptomes were generated for both dead and alive rhodoliths (15.48 million Illumina reads in total). Alive rhodoliths showed an enrichment of gene transcripts related to environmental stress responses and photosynthesis (Cyanobacteria). In contrast, the metatranscriptomes of dead rhodoliths were dominated by heterotrophic (Proteobacteria and Bacteroidetes) metabolism and virulence factors. The rhodolith holobiont metatranscriptomes respond rapidly to short-term acidification (within 1 h), suggesting that these holobionts may have some capacity to cope with acute acidification effects. However, the negative impacts of prolonged ocean acidification on rhodolith health cannot be overlooked. Rhodoliths exposed to low pH (7.5) for 96 h exhibited a completely altered transcriptomic profile compared to controls. This study highlights the plasticity of rhodolith transcriptomes in the face of ocean acidification and climate change.
Continue reading ‘Short-term negative effects of seawater acidification on the rhodolith holobionts metatranscriptome’Understanding and quantifying carbon export to coastal oceans through deltaic systems
Published 7 February 2025 Science ClosedTags: chemistry, modeling, North Atlantic, regionalmodeling
The ocean is the second largest carbon reservoir on Earth and a significant carbon sink to mitigate the adverse effects of climate change. However, ocean carbon sink is expected to decrease in the future with continuing seawater acidification, more stable ocean stratification, and intensified extreme weather events. Estuaries, the connection between land and the coast, undergo complex carbon reforming and pose the greatest uncertainty in global carbon budgets. Coupled physical-biogeochemical models over the Gulf of Mexico (GoM) were configured using biogeochemical boundary conditions from a global climate model (GCM), preserving the long-term climate variability and the conservation of carbon pools in the regional model (RM). Subsequently, a nested domain over the Barataria Basin was built to quantify the carbon export in the eroding estuary. Intensive model-data comparison confirmed that the RM could reliably simulate the ocean carbon system in the GoM, and added values (AVs) were achieved both at the GCM scale and the RM scale. Model results reveal that the GoM water has been experiencing a ~ 0.0016 yr-1 decrease in surface pH over the past two decades, accompanied by a ~ 1.66 µatm yr-1 increase in sea surface pCO2. The river-dominated northern GoM (NGoM) is a substantial carbon sink, and the open GoM is a carbon source during summer and a carbon sink for the rest of the year. Based on the sensitivity test for higher river discharge scenarios, the NGoM was predicted to become a stronger ocean CO2 sink in the future. Stronger fluvial influence will increase the ecosystem resilience after hurricanes’ impact but reduce its resistance at the same time. The model estimated that Barataria Basin exports approximately 52.5 ×106 kg yr-1 dissolved inorganic carbon (DIC) and 9.68 ×106 kg yr-1 total organic carbon (TOC) to the coastal water. The biggest carbon loss term of the Barataria Basin was in the form of CO2 outgassing in quantity of 98.8×106 kg yr-1.
Continue reading ‘Understanding and quantifying carbon export to coastal oceans through deltaic systems’
