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’Archive Page 52
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
Morphological responses of a temperate salt marsh foraminifer, Haynesina sp., to coastal acidification
Published 15 January 2025 Science ClosedTags: biological response, laboratory, morphology, North Atlantic, protists
Coastal acidification leads to widespread impacts on calcifying organisms across the world’s oceans, which could result in decreased calcium carbonate deposition and the dissolution of calcium carbonate. As an abundant group of calcifying organisms, some protists within the phylum Foraminifera demonstrate potential success under elevated partial pressure of carbon dioxide (pCO2) due to their ability to modulate intracellular pH. However, little is known about their responses under more extreme acidification conditions that are already seen in certain coastal environments. Here we exposed Haynesina, a foraminiferal genus that is prevalent in temperate coastal salt marshes, to moderate (pCO2 = 2386.05+/-97.14 μatm) and high acidification (pCO2 = 4797.64+/-157.82 μatm) conditions through the duration of 28 days. We demonstrate that although this species is capable of withstanding moderate levels of coastal acidification with little impact on their overall test thickness, they could experience deposition deficiency and even dissolution of the calcareous test under highly elevated pCO2. Interestingly, such a deficit was primarily seen among live foraminifera, as compared to dead specimens, throughout the four-week experiment. We propose that a combination of environmental stress and the physiological process of test formation (i.e., calcite precipitation) could induce thinning of the test surface. Therefore, with the acceleration of coastal acidification due to anthropogenic production of CO2, benthic foraminifera amongst coastal ecosystems could reach a tipping point that leads to thinning and dissolution of their calcareous tests, which in turn, will impair their ecological function as a carbon sink.
Continue reading ‘Morphological responses of a temperate salt marsh foraminifer, Haynesina sp., to coastal acidification’A machine-learning reconstruction of sea surface pCO2 in the North American Atlantic Coastal Ocean Margin from 1993 to 2021
Published 15 January 2025 Science ClosedTags: chemistry, modeling, North Atlantic, regionalmodeling
Insufficient spatiotemporal coverage of observations of the surface partial pressure of CO2 (pCO2) has hindered precise carbon cycle studies in coastal oceans and justifies the development of spatially and temporally continuous pCO2 data products. Earlier pCO2 products have difficulties in capturing the heterogeneity of regional variations and decadal trends of pCO2 in the North American Atlantic Coastal Ocean Margin (NAACOM). This study developed a regional reconstructed pCO2 product for the NAACOM (Reconstructed Coastal Acidification Database-pCO2, or ReCAD-NAACOM-pCO2) using a two-step approach combining random forest regression and linear regression. The product provides monthly pCO2 data at 0.25 degrees spatial resolution from 1993 to 2021, enabling investigation of regional spatial differences, seasonal cycles, and decadal changes in pCO2. The observation-based reconstruction was trained using Surface Ocean CO2 Atlas (SOCAT) observations as observational values, with various satellite-derived and reanalysis environmental variables known to control sea surface pCO2 as model inputs. The product shows high accuracy during the model training, validation, and independent test phases, demonstrating robustness and a capability to accurately reconstruct pCO2 in regions or periods lacking direct observational data. Compared with all the observation samples from SOCAT, the pCO2 product yields a determination coefficient of 0.92, a root-mean-square error of 12.70 mu atm, and an accumulative uncertainty of 23.25 mu atm. The ReCAD-NAACOM-pCO2 product demonstrates its capability to resolve seasonal cycles, regional-scale variations, and decadal trends of pCO2 along the NAACOM. This new product provides reliable pCO2 data for more precise studies of coastal carbon dynamics in the NAACOM region. The dataset is publicly accessible at https://doi.org/10.5281/zenodo.14038561 (Wu et al., 2024a) and will be updated regularly.
Continue reading ‘A machine-learning reconstruction of sea surface pCO2 in the North American Atlantic Coastal Ocean Margin from 1993 to 2021’Natural fluctuation of pH in shallow-water macrophyte habitats in the brackish Baltic Sea
Published 15 January 2025 Science ClosedTags: algae, Baltic, biological response, chemistry, field
The pH declines caused by increasing atmospheric CO2 as defined term “ocean acidification”, are more predictable in open ocean surface waters than in coastal seas. The pH of coastal waters is inherently more variable due to the effects of different factors, for example, temperature, biological uptake and respiration, pollution, and terrestrial run-off. Benthic macrophytes are important structural components in coastal ecosystems, playing crucial roles as primary producers and habitat formers. In this coastal ecosystem, the daily pH fluctuation is also strongly affected by algal photosynthesis (increasing pH) and respiration (lowering pH). In this study, we investigated the diurnal fluctuations in pH in shallow-water macroalgal habitats in July and August 2023 in the Estonian coastal waters, NE Baltic Sea. The study sites were chosen to represent different compositions of macrophyte species and environmental conditions. Measurements were carried out at each site for a full 24-hour cycle at a 5-meter depth during the active growth period. In addition, water temperature, and photosynthetically active radiation (PAR) were measured continuously at each site. Biomass samples were collected by scuba divers from surrounding macrophyte communities. Our results showed that the pH values at different study sites exhibited large daily variations as well as large variations during the study period. Within the study period, the pH fluctuations in different sites exceeded 1 unit, which is higher than pH changes owing to ocean acidification predicted for surface ocean waters by 2100. Our results suggested that besides local environmental conditions, the magnitude of pH changes in shallow coastal waters depends on the carbon use strategies of macrophytes as well as the community biomass. Overall, this natural fluctuation in pH in shallow coastal waters is important to incorporate into future climate change prediction scenarios.
Continue reading ‘Natural fluctuation of pH in shallow-water macrophyte habitats in the brackish Baltic Sea’Nutrient physiology of siliceous phytoplankton under warming and acidification in Arctic and subtropical oceans
Published 14 January 2025 Science ClosedTags: biological response, laboratory, physiology, phytoplankton
Steadily rising atmospheric CO2 concentrations have the potential to impact marine ecosystems by increasing the temperature and acidity of the world’s oceans. In the sunlit upper ocean, phytoplankton affect elemental cycling and contribute to nutrient export to deeper waters by incorporating nutrients into biomass and supporting higher tropic levels. One unique group of phytoplankton, diatoms, are characterized by their typically larger size and heavy silica frustules, and they make considerable contributions to global primary productivity. Diatoms are expected to be impacted by oceanic change in various ways, but the degree of this effect is still uncertain. The overall objective of this thesis is to improve our understanding of how marine diatom physiology, specifically the utilization of silicon (Si), and the contribution by diatoms to the cycles of carbon (C) and nitrogen (N), are affected by climate-induced increases in temperature and acidification. I investigated the impact of mesoscale physical processes on diatom contributions to utilization rates of C (ρC) and nitrate (ρNO3) in the Sargasso Sea in the North Atlantic subtropical gyre, an ecosystem impacted by increased stratification due to ocean warming. Diatoms played a minor role in nutrient utilization and biomass during the lowest-productivity time of year, but they dominated nutrient utilization rates in the deeper euphotic zone of the Sargasso Sea when nutrient concentrations were enhanced by eddy-driven upwelling. In the contrasting environment of the Bering and Chukchi Seas, I investigated the effects of a warming ocean on diatom physiology and elemental composition as part of an on-going oceanographic time-series in the Pacific Arctic Region (PAR). I found significant trends in ocean temperature and sea ice breakup dates for different regions of the PAR, and evidence for declining diatom biomass in one area of the northern Bering Sea. Anomalously low particulate C:N values were observed across the PAR during the 2019 MHW, but otherwise the response of diatom assemblages in the PAR to a sustained warming period and marine heatwave (MHW) in 2019 varied substantially. Estimates of diatom contributions to ρC and ρNO3 in the PAR were improved compared to previous studies, demonstrating that diatoms were responsible for most of the nutrient utilization in all regions. Ocean acidification experiments were conducted with a model diatom species and two natural phytoplankton assemblages to assess the effects of decreased pH on nutrient physiology. Overall, diatom Si utilization and silicification in laboratory and field culture experiments were unaffected by pH. I found that the cell size of a model species of diatom, Thalassiosira rotula, decreased under OA, while in subtropical and Arctic phytoplankton assemblages, OA had no conclusive meaningful impacts on other measures of physiology, or assemblage composition. This dissertation provides valuable insights into how siliceous phytoplankton, particularly diatoms, interact with marine cycles of Si, C, and N across cold and warm marine ecosystems. It also deepens our understanding of how these dynamic systems may respond to oceanic change, and sets the stage for future research on the evolving impacts of climate-driven physical processes.
Continue reading ‘Nutrient physiology of siliceous phytoplankton under warming and acidification in Arctic and subtropical oceans’The impact of climate change stressors on microbial respiration and community structure: ocean acidification and artificial upwellling
Published 14 January 2025 Science ClosedTags: biological response, BRcommunity, community composition, field, mesocosms, multiple factors, North Atlantic, nutrients, otherprocess, physiology, phytoplankton, prokaryotes, respiration
Microbial community respiration significantly influences the oceans capacity to sequester CO2 in marine ecosystems. Despite its pivotal role, there remains limited understanding of the variability and magnitude of community respiration in marine ecosystems, especially regarding its sensitivity to climate change stressors. This knowledge gap hinders a comprehensive grasp of its contribution to the global carbon cycle. Traditional in situ approaches for measuring community respiration are subject to several methodological limitations, particularly that of sensitivity in oligotrophic ecosystems, which cover more than 40% of the Earth’s ocean surface. These limitations thus contribute significantly to the uncertainty in global estimates of carbon budgets. To address these challenges, enzymatic techniques such as ETSvitro offer a fast and sensitive method to assess respiratory activity rates at spatial scales that are difficult to cover using conventional approaches. The method involves reducing the tetrazolium salt, INT, within the respiratory chain under substrate saturation levels (i.e., NADH, NADPH, and succinate). However, the reliability of the ETSvitro method has been questioned because it measures potential respiratory activity rather than actual respiration. In response to these concerns, another enzymatic technique, ETSvivo, emerged presumably as a more realistic estimate of actual respiration. Unlike ETSvitro, ETSvivo measures INT under in vivo conditions, utilizing substrates naturally available inside the cell. Nevertheless, before these methods can be considered feasible proxies for community respiration, further evaluation is needed to determine their universal applicability in marine ecosystems. In this thesis, our objective was to improve our understanding of community respiration by addressing its methodological limitations and investigating the drivers responsible for its variability. We paid particular attention to planktonic community structure and the impact of two climate change stressors: ocean acidification and changes in nutrient fertilization. Simulating a typical ETSvivo assay in eight independent experiments using surface coastal and open ocean waters from the Canary region, we observed that INT alone significantly influences the physiological status of bacteria. Bacteria are considered the primary contributors to respiration in oligotrophic environments, but their physiological status is largely affected by the inherent toxicity of INT. Consequently, we question the applicability of the ETSvivo method as a proxy for community respiration in oligotrophic regions. On the other hand, we explore the temporal variability of respiratory metabolism through two mesocosm experiments conducted in the oligotrophic waters of the subtropical Eastern North Atlantic. In the first mesocosms experiment, we investigated the impact of changing community structure and biomass on the temporal variability of community respiration measured through the Winkler method (R), ETS activity, and their ratio (R/ETS) in response to increasing CO2 concentrations and nutrient fertilization (e.g., due to local upwelling events). Our results suggest that community respiration and ETS activity do not respond to CO2 during oligotrophic conditions. However, following fertilization, community respiration increased in the two high CO2 mesocosms coinciding with an increase in microplankton, primarily diatoms. Simultaneously, the R/ETS ratio showed no correlation with community structure or biomass, indicating its variability makes it unsuitable for application with communities undergoing abrupt changes in trophic conditions. In light of these findings, the second mesocosm experiment explored the influence of different upwelling intensities and frequencies (singular pulse versus recurring upwelling) on community respiration. Our results demonstrate that community respiration is sensitive to changes in upwelling intensities but more significantly to the mode in which nutrients are supplied to oligotrophic waters. The planktonic community structure significantly influenced the observed variability in community respiration, revealing notable differences under varying upwelling intensities.The results of this thesis underscore the significance of mitigating methodological uncertainties to achieve precise measurements of respiration rates. It is crucial to adequately assess the impact of climate change-induced stressors, especially ocean acidification and changes in nutrient fertilization, along with planktonic community structure, as drivers of temporal variability. This thorough examination is essential for gaining a deeper understanding and, consequently, making more accurate predictions of community respiration in marine ecosystems.
Ocean acidification a murky phenomenon with little research done, say scientists
Published 14 January 2025 Media coverage ClosedTags: Indian
Ocean acidification—a critical yet understudied issue in Sri Lanka—results from increased atmospheric CO2 levels dissolving into the ocean, altering its chemistry. This phenomenon poses significant threats to marine biodiversity and ecosystems, yet research efforts remain constrained by limited data, coordination, and resources.
“Four years ago, NARA established two permanent stations to measure and monitor pH levels—one off the western coast of Sri Lanka, covering the Arabian Sea, and the other off Trincomalee, for the Bay of Bengal,” says Dr K. Arulananthan, Director General of the National Aquatic Resources Research and Development Agency (NARA). These stations aim to collect long-term data to understand oceanic changes better.
“The Sri Lankan government has funded these initiatives through the Treasury. While we’ve observed strong seasonal variations in pH levels, such fluctuations—lower during the rainy season and higher during dry periods—are natural and normal,” he explains. However, Dr. Arulananthan notes that four years of data is insufficient to establish definitive trends.
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Dr. Arulananthan emphasised the interconnectedness of pH levels and carbon dioxide. “Acidification is directly related to CO2. While Sri Lanka’s emissions are negligible, making us not a major contributor, the responsibility lies with big emitters. However, we do have significant ecosystems, such as mangroves, that help absorb CO2. Replanting mangroves is a major step forward,” he notes.
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“Measuring pH and observing its changes is a very basic analysis that alone cannot reflect acidification. To establish a trend and study the impact, we need data from multiple locations over a long period,” says Prof. Terney Pradeep Kumara, Professor of Oceanography at the University of Ruhuna, Sri Lanka.
According to Prof. Terney, the lack of proper coordination in data collection and processing is a major obstacle to understanding ocean acidification trends in Sri Lanka. “Data collection happens, but the information is not collated well enough, and we don’t have sufficient trend records to quantify acidification. However, there is evidence to suggest that changes are occurring,” he notes.
The professor highlighted the absence of state-of-the-art technology as another critical challenge. “We need more advanced tools, such as data loggers on reefs and rocks, to analyse long-term trends. Right now, no reliable data is being created,” he says.
While global scenarios of ocean acidification have been studied extensively, Prof. Terney pointed out the gap in localised research. “We don’t have our own data, so we can’t conclusively say what the impact is. Theoretically, we can assume coral growth rates are changing, but we haven’t connected those changes to acidification. We haven’t calculated calcification rates,” he explains.
Globally, scientists have not observed clear trends linking acidification to coral growth rates, but Prof. Terney emphasised the importance of monitoring Sri Lanka’s unique conditions. “Different parts of the ocean around Sri Lanka exhibit varying pH levels due to local factors such as river discharges. For example, Trincomalee’s deep channel is influenced by the Mahaweli River, so it cannot serve as the focal point for data extraction,” he says.
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“The root cause of acidification is climate change because the increase of CO2 in our atmosphere leads to ocean acidification,” says Dr. Sivakumaran Sivaramanan, Environmental Assessor at the Central Environmental Authority (CEA). According to Dr Sivaramanan, addressing climate change is essential to mitigating ocean acidification. “Global and local attempts to tackle global warming will naturally reduce acidification. But any meaningful climate effort—whether in research, mitigation, or adaptation—usually takes about a decade of consistent work to yield results,” he explains.
Dr. Sivaramanan highlights the challenges in advancing research locally. “Research in this area is moving slowly because it demands significant time and funding. You need to measure everything consistently to gain actionable insights,” he says. While awareness programs are being conducted, mitigation strategies require robust data and consistent action. “The only permanent solution is to resolve the climate crisis,” he emphasises.
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The initial impacts of acidification, he notes, will primarily affect marine biodiversity. “Fish migration patterns will change as the Indian Ocean, particularly around Sri Lanka, is a biodiversity hotspot. Large marine animals like whales will also feel the effects. It’s a chain reaction—corals are affected first, followed by species dependent on them, and the impacts ripple through the ecosystem,” he says.
Dr. Sivaramanan also addresses misconceptions about acidification. “Some assume that eutrophication leads to acidification because nutrient-induced algal blooms block sunlight, slowing photosynthesis and creating anoxic conditions. While this must be mitigated, it does not cause acidification directly,” he clarifies. “The root cause is climate change.”
Continue reading ‘Ocean acidification a murky phenomenon with little research done, say scientists’Ocean acidification and its regulating factors in the East China Sea off the Yangtze River estuary
Published 14 January 2025 Science ClosedTags: chemistry, field, modeling, North Pacific, regionalmodeling
Highlights
- Summer surface photosynthesis counteracts acidification from anthropogenic CO₂.
- Summer bottom respiration contributes more to acidification than anthropogenic CO₂.
- Winter acidification mainly driven by rising atmospheric CO₂; minimal biological impact.
- Buffering capacity and DIC:TA ratio crucially impact future pH and Ωar decline rates.
Abstract
This study examines the seasonal variations in carbonate system parameters in the East China Sea (ECS) off the Yangtze River estuary (YRE) and analyzes the contributions of anthropogenic CO₂ and eutrophication to acidification. Carbonate parameters data were collected during summer 2019 and combined winter 2011. During winter, acidification is primarily driven by rising atmospheric CO₂, with minimal impact from biological processes. In contrast, summer presents a different pattern: enhanced photosynthesis due to eutrophication in surface waters helps mitigate the acidification effects of atmospheric CO₂ increases, while in bottom waters, the combined pressures of atmospheric CO₂ and intensified aerobic respiration leads to more severe acidification. Notably, biological processes now contribute more to acidification than increasing atmospheric CO₂ in the bottom waters. Our projections indicate that the summer bottom waters will experience the most pronounced acidification, with average pH levels expected to decline from 8.04 to 7.82 and aragonite saturation state (Ωar) values decreasing from 2.24 to 1.38 between 2000 and 2100. Additionally, our study indicates that winter acidification trends are also concerning, with pH only slightly higher than in summer bottom waters. The buffering capacity and the DIC:TA ratio play significant roles in determining the rate of future pH and Ωar declines. The strong buffering capacity in summer surface waters mitigates the pH decline, while the low DIC:TA ratio results in a rapid drop in Ωar.
Continue reading ‘Ocean acidification and its regulating factors in the East China Sea off the Yangtze River estuary’Assessing the impact of landwater on the northwest Pacific using normalized total alkalinity
Published 14 January 2025 Science ClosedTags: chemistry, field, North Pacific
The impact of landwater was assessed using salinity-normalized Total Alkalinity observations. The observational data included surface carbonate parameters from decades of surveys conducted by volunteer cargo ships and research vessels in the Northwest Pacific. Statistical processes, such as re-gridding and Fourier regression, used in a previous study were also applied in this study to improve the spatiotemporal resolution. First, the seawater area affected by landwater was identified using an Empirical Orthogonal Function analysis of normalized Total Alkalinity. The differences in normalized Total Alkalinity and Dissolved Inorganic Carbon from the surrounding area were then analysed to evaluate the causes such as landwater supply, advection effects, and biological activities. In addition, the impact of landwater on oceanic CO2 uptake and acidification in the study area was assessed. The analysis showed that landwater was the main source of total coastal Alkalinity but was not the dominant cause of Dissolved Inorganic Carbon. The supply of landwater had little effect on oceanic CO2 uptake throughout the year. The supply of by landwater was a factor in coastal acidification; however, the supplied Total Alkalinity reduced the overall acidification trend by 65%. The results of this study are expected to be further improved by enhancing observations, such as the vertical profiles of carbonate parameters, and are expected to expand to other sea areas and be applied to global budgets.
Continue reading ‘Assessing the impact of landwater on the northwest Pacific using normalized total alkalinity’Molecular response to CO2-driven ocean acidification in the larvae of the sea urchin Hemicentrotus pulcherrimus: evidence from comparative transcriptome analyses
Published 13 January 2025 Science ClosedTags: biological response, echinoderms, laboratory, molecular biology, morphology, North Pacific, reproduction
Highlights
- Ocean acidification affects morphology of Hemicentrotus pulcherrimus larvae.
- Comparative transcriptome analyses were performed.
- Six key potential biomarkers correlated with low pH tolerance were identified.
Abstract
In order to explore the impact of CO2-driven ocean acidification (OA) on gene expression of sea urchins, gametes of Hemicentrotus pulcherrimus were fertilized and developed to the four-armed larvae in either seawater at current pH levels (pHNBS = 7.98) or in three laboratory-controlled OA conditions (ΔpHNBS = −0.3, −0.4, −0.5 units) based on the projections of the Intergovernmental Panel on Climate Change (IPCC) for 2100. Four-armed larval specimens were collected, and comparative transcriptome analysis was then performed. The results showed that 58 differentially expressed genes (DEGs) were identified in OA-treated groups as compared to the control. Moreover, more transition and transversion SNPs were observed in OA-treated groups than those in the control indicating a potential occurrence of adaption to OA in H. pulcherrimus larvae. Six candidate DEGs shared among OA-treated groups were identified as potential biomarkers correlated with low pH tolerance, mainly enriched in nine pathways associated with Notch signaling, dorso-ventral axis formation, oxidative phosphorylation, lysine degradation, valine, leucine and isoleucine degradation, lysosome, cell adhesion molecules, glutathione metabolism and PPAR signaling pathway. These results will not only enrich our knowledge of the impacts of OA on sea urchin larvae from the aspect of gene expression, provide a better understanding on larval forms coping with OA, but also offer more clues and biomarkers for developing protection or management strategies for sea urchins under near-future OA conditions.
Continue reading ‘Molecular response to CO2-driven ocean acidification in the larvae of the sea urchin Hemicentrotus pulcherrimus: evidence from comparative transcriptome analyses’Addressing ocean acidification through a fit-for-purpose capacity building program
Published 13 January 2025 Web sites and blogs Closed
Dupont et al., (2024)
A large body of evidence is documenting the impact of ocean acidification on marine species and ecosystems. While there is enough evidence to support global actions toward CO2 mitigation, local data are needed to develop and implement adaptation solutions. These data are often lacking, especially in developing countries. This article summarises the work done over the last 11 years by the International Atomic Energy Agency (IAEA) Ocean Acidification International Coordination Centre, in close collaboration with SOLAS and Integrated Marine Biosphere Research (IMBER), to promote best practices for ocean acidification research adapted to local needs and existing capacity, with a strong focus on the global south. It describes a goal-oriented and evidence-based capacity building strategy that can be used by intergovernmental organisations, nongovernmental organisations, and other institutions engaged in capacity development.
Reference: Dupont S., Edworthy C., Sanchez-Noguera C., Metian M., Friedrich J., Flickinger S., Banterman A., Galdino C., Graba F., Anghelici O. & Hansson L., 2024. The IAEA ocean acidification international coordination centre capacity building program: empowering member states to address and minimize the impacts of ocean acidification. Oceanography 38(1): 26-0. https://doi.org/10.5670/oceanog.2025.102
Continue reading ‘Addressing ocean acidification through a fit-for-purpose capacity building program’Taking the pulse of our ocean: exploring biodiversity responses to global change.
Published 13 January 2025 Courses and training , Events ClosedAbout
The PulseOcean Summer School, hosted at the Ischia Marine Center in Italy, is a pioneering training initiative addressing critical marine challenges such as climate change, blue carbon, biodiversity, and emerging technologies. Tailored for Master’s and PhD students, it combines lectures, fieldwork, and lab-based projects, offering hands-on experience with cutting-edge tools like AI, in situ sensors, and imaging technologies. This interdisciplinary program fosters critical thinking, career development, and collaboration while advancing open and reproducible science. Aligned with the UN Decade of Ocean Science and Horizon Europe’s “Digital Twin Ocean,” PulseOcean highlights its commitment to research excellence and knowledge exchange across Europe.
Key Objectives
- Train in Advanced Marine Research Techniques: Equip participants with hands-on experience in in situ instrumentation, AI-based image analysis, and fieldwork surveys using cutting-edge tools such as underwater photography, drone surveys, and carbonate chemistry.
- Promote Open and Reproducible Science: Emphasize best practices for transparent research through training in open-source platforms like GitHub for data and code sharing.
- Foster Interdisciplinary Learning: Provide a multidisciplinary environment that integrates climate science, biodiversity, blue carbon, and technological advancements to address ocean transformation.
- Encourage Collaborative Research: Facilitate teamwork on real-world projects, combining field and lab methods to solve critical marine science challenges.
- Develop Critical and Independent Thinking: Cultivate analytical skills and professional maturity to enable participants to critically evaluate methodologies and contribute innovative solutions.
- Strengthen Professional Networks: Build connections among an international cohort of peers and instructors, fostering long-term collaborations and knowledge exchange.
- Support Inclusive Participation: Ensure diverse representation by promoting geographical, age, and gender balance in participant selection, enhancing a global and inclusive perspective in marine science.
Expected Impact
The PulseOcean EuroMarine Summer School will have a profound impact by addressing urgent ocean challenges and fostering innovation in marine science. Aligned with the priorities of the EuroMarine network, the course focuses on advancing marine biodiversity conservation, understanding ocean transformation, and supporting sustainable practices. It emphasizes cutting-edge technologies, such as AI-based image analysis and in situ sensors, combined with practical fieldwork and interdisciplinary collaboration. By training the next generation of researchers with hands-on experience and promoting reproducible science, PulseOcean strengthens the EuroMarine network, enhances global research capacity, and contributes to the UN Decade of Ocean Science and SDGs, particularly SDG 13 (Climate Action) and SDG 14 (Life Below Water). The Summer School will also enhance EuroMarine’s visibility and outreach, fostering a network of researchers ready to tackle critical ocean issues collaboratively and equitably.
Registration
We will post the details about registration and participation for this Summer School in February 2025. The Summer School will take place in September 2025.
Continue reading ‘Taking the pulse of our ocean: exploring biodiversity responses to global change.’Effect of CO2 driven seawater acidification on survival, growth, amino acid and fatty acid levels in the edible shrimp Litopenaeus vannamei
Published 13 January 2025 Science ClosedTags: biological response, crustaceans, growth, laboratory, mortality, physiology
Highlights
- Survival and growth of L. vannamei were declined in OA exposures
- Essential and nonessential amino acids were decreased in shrimps under OA
- Vital unsaturated fatty acids were improved in shrimps under OA conditions
Abstract
Acidification in the ocean environment is considered a worldwide problem that drives serious consequences for organisms. The current investigation was focused to study the effect of CO2 induced ocean acidification (OA) on the survival, growth, and composition of amino acids and fatty acids in the shrimp Litopenaeus vannamei. A seven weeks OA experiment was conducted on the shrimp groups with different pH such as 8.2 (control), 7.8, 7.6, 7.4, 7.2, and 7.0. A considerable decline in survival, growth, essential and nonessential amino acids, and saturated fatty acids in shrimps under OA exposures (pH 7.8 to 7.0). In this context, a notable improvement in amino acids (histidine, alanine, and cysteine) and fatty acids (palmitoleic acid, linoleic acid, linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid) in L. vannamei reared under acidified seawater environments suggests that the high demand for these amino acids and fatty acids to tolerate the acidic stress.
Continue reading ‘Effect of CO2 driven seawater acidification on survival, growth, amino acid and fatty acid levels in the edible shrimp Litopenaeus vannamei’Uncertainties about the role of river and mangrove dissolved inorganic carbon and alkalinity loads in buffering the Great Barrier Reef lagoon
Published 13 January 2025 Science ClosedTags: chemistry, field, South Pacific
Terrestrial dissolved inorganic carbon (DIC) and total alkalinity (TAlk) loads have contrasting effects on the pH and carbonate chemistry of the coastal ocean. While TAlk can buffer against ocean acidification, elevated exports of free CO2 can further exacerbate ocean acidification. In this study, we quantify terrestrial DIC and TAlk loads from rivers and mangrove floodplains across six bioregions and varying flow conditions to assess their impact on the buffering capacity of the Great Barrier Reef (GBR) lagoon in Australia. For a mid-flow year, median terrestrial DIC and TAlk loads ranged from 0.72 to 0.89 Tg C yr−1 and 0.26 to 1.03 Tg C yr−1, respectively. We find that mangrove-dominated terrestrial inputs only have a small influence on the whole GBR but contribute 12.5% (range: 1.9%–45.7%) of the DIC and 18.7% (range: 2.8%–68.2%) of the TAlk inner shelf inventory. Depending on the approach used to estimate TAlk loads, mangroves have a potential short-term buffering effect on near-shore coastal waters due to higher TAlk loads. However, long-term mangrove TAlk production via pyrite formation complicates this interpretation, highlighting the need for ongoing monitoring to understand the complex interplay between terrestrial inputs and their effect on the GBR carbonate chemistry.
Key Points
- Current measurement uncertainties hinder our ability to accurately predict the effects of terrestrial inputs on the GBR coastal waters
- Mangrove floodplains dominate terrestrial dissolved inorganic carbon (DIC) and total alkalinity (TAlk) loads to the Great Barrier Reef (GBR) lagoon
- Terrestrial loads of DIC and TAlk are higher in high flow years and in tropical wet bioregions with localized effects on the GBR lagoon
Distribution and affecting factors of aragonite saturation in the northern South China Sea in summer
Published 10 January 2025 Science ClosedTags: chemistry, field, North Pacific
Based on the carbonate and hydrological parameters of a survey made in August–September 2011, we investigated the distribution and affecting factors of aragonite saturation (Ωarag) in the northern South China Sea. The levels of Ωarag were found to gradually decrease with depth in the northern South China Sea. Surface-water Ωarag values ranged from 2.56 to 3.68, with the highest value occurring in the region of Pearl River-diluted water near the northern coast. The increase in Ωarag due to primary production, stimulated by the Pearl River freshwater input, exceeded the decrease in Ωarag due to the direct input of low-Ωarag fresh water, resulting in high Ωarag in that area. In contrast, Ωarag levels below 2 generally appeared in subsurface water below 50 m in depth. Intense community respiration was the main reason for the low Ωarag. By 2100, bottom-water Ωarag levels could be lower than 1.7, and even the undersaturation of aragonite could appear, due to the oceanic absorption of atmospheric CO2.
Continue reading ‘Distribution and affecting factors of aragonite saturation in the northern South China Sea in summer’Climate change and polar marine invertebrates: life-history responses in a warmer, high CO2 world
Published 10 January 2025 Science ClosedTags: Antarctic, Arctic, biological response, review
Polar marine invertebrates serve as bellwethers for species vulnerabilities in the face of changing climate at high latitudes of the Earth. Ocean acidification, warming/heatwaves, freshening, sea ice retreat and productivity change are challenges for polar species. Adaptations to life in cold water with intensely seasonal productivity has shaped species traits at both poles. Polar species have life histories often characterised as K-strategist or K-selected (e.g. slow growth and development, larval hypometabolism) that make them sensitive to climate stress and altered seasonal productivity. Moderate warming results in faster development and can have positive effects on development, up to a limit. However, ocean acidification can retard development, impair skeletogenesis and result in smaller larvae. Given the fast pace of warming, data on the thermal tolerance of larvae from diverse species is urgently needed, as well as knowledge of adaptive responses to ocean acidification and changes to sea ice and productivity. Predicted productivity increase would benefit energy-limited reproduction and development, while sea ice loss negatively impacts species with reproduction that directly or indirectly depend on this habitat. It is critical to understand the interactive effects between warming, acidification and other stressors. Polar specialists cannot migrate, making them susceptible to competition and extinction from range-extending subpolar species. The borealisation and australisation of Arctic and Antarctic ecosystems, respectively, is underway as these regions become more hospitable for the larval and adult life-history stages of lower-latitude species. Differences in biogeography and pace of change point to different prospects for Arctic and Antarctic communities. In this Commentary, we hypothesise outcomes for polar species based on life history traits and sensitivity to climate change and suggest research avenues to test our predictions.
Continue reading ‘Climate change and polar marine invertebrates: life-history responses in a warmer, high CO2 world’Multi-interacting global-change drivers reduce photosynthetic and resource use efficiencies and prompt a microzooplankton-phytoplankton uncoupling in estuarine communities
Published 10 January 2025 Science ClosedTags: biological response, BRcommunity, community composition, laboratory, otherprocess, photosynthesis, phytoplankton, protists, South Atlantic, zooplankton
Highlights
- Multi-interacting driver effects were evaluated on South Atlantic estuarine plankton
- Warming×pH×nutrients×UVR reduced the photosynthetic and resource use efficiencies
- A multi-driver change condition prompted a microzooplankton-phytoplankton uncoupling
- Altered trophic interactions could reduce the energy transfer efficiency in food webs
Abstract
Plankton communities are subjected to multiple global change drivers; however, it is unknown how the interplay between them deviates from predictions based on single-driver studies, in particular when trophic interactions are explicitly considered. We investigated how simultaneous manipulation of temperature, pH, nutrient availability and solar radiation quality affects the carbon transfer from phytoplankton to herbivorous protists and their potential consequences for ecosystem functioning. Our results showed that multiple interacting global-change drivers reduced the photosynthetic (gross primary production-to-electron transport rates ratios, from 0.2 to 0.6-0.8) and resource use efficiencies (from 9 to 1 μg chlorophyll a (Chl a) μmol nitrogen-1) and prompted uncoupling between microzooplankton grazing (m) and phytoplankton growth (μ) rates (μ > m). The altered trophic interaction could be due to enhanced intra-guild predation or to microzooplankton growing at suboptimal temperatures compared to their prey. Because phytoplankton-specific loss rates to consumers grazing are the most significant uncertainty in marine biogeochemical models, we stress the need for experimental approaches quantifying it accurately to avoid bias in predicting the impacts of global change on marine ecosystems.
Continue reading ‘Multi-interacting global-change drivers reduce photosynthetic and resource use efficiencies and prompt a microzooplankton-phytoplankton uncoupling in estuarine communities’Microplastic hotspots mapped across the Southern Ocean reveal areas of potential ecological impact
Published 9 January 2025 Science ClosedTags: Antarctic, biological response, chemistry, crustaceans, phytoplankton, review, zooplankton
Marine microplastic is pervasive, polluting the remotest ecosystems including the Southern Ocean. Since this region is already undergoing climatic changes, the additional stress of microplastic pollution on the ecosystem should not be considered in isolation. We identify potential hotspot areas of ecological impact from a spatial overlap analysis of multiple data sets to understand where marine biota are likely to interact with local microplastic emissions (from ship traffic and human populations associated with scientific research and tourism). Then we account for cumulative effects by identifying which areas with potential elevated microplastic-biota interaction are already subject to climate change related stresses (ocean warming and acidification). Our analysis indicates that biologically productive coastal areas in proximity to populated facilities are where microplastics pose most risk to the ecosystem, and that the northern Antarctic Peninsula is likely to be the main risk hotspot. This study is the first to map the threat of microplastics to the Southern Ocean ecosystem in a multi-stressor context, locating where microplastic monitoring programmes and mitigation measures may be considered a matter of urgency.
Continue reading ‘Microplastic hotspots mapped across the Southern Ocean reveal areas of potential ecological impact’Prediction technology of ocean acidification based on quantum particle swarm optimization and long short-term memory network
Published 9 January 2025 Science ClosedTags: methods, modeling
In this paper, the ocean acidification prediction problem was studied deeply, and a new prediction model was constructed by using quantum particle swarm optimization algorithm (QPSO) and long short-term memory neural network (LSTM). Firstly, by introducing the quantum particle swarm optimization algorithm, the limitations of the traditional particle swarm optimization algorithm in search accuracy and global search ability are overcome, and the convergence speed and prediction accuracy of the model are improved. Secondly, using the ability of long short-term memory neural network to process time series data, it effectively captures the long-term dependence relationship in ocean acidification data, and further enhances the prediction ability of the model. Finally, through a series of experimental verification and performance evaluation, including root mean square error (RMSE), mean absolute error (MAE), mean absolute percentage error (MAPE) and coefficient of determination (R2), it is proved that the model has high accuracy and generalization ability in ocean acidification prediction. The model provides a new method for the effective prediction of ocean acidification.
Continue reading ‘Prediction technology of ocean acidification based on quantum particle swarm optimization and long short-term memory network’Ocean acidification and global warming may favor blue carbon service in a Cymodocea nodosa community by modifying carbon metabolism and dissolved organic carbon fluxes
Published 9 January 2025 Science ClosedTags: biogeochemistry, biological response, laboratory, mesocosms, morphology, multiple factors, North Atlantic, phanerogams, physiology, primary production, respiration, temperature
Highlights
- 45-days mesocosm experiment with whole-benthic community to mimic nature conditions
- Global warming (GW) and ocean acidification (OA) modify C dynamics on seagrasses.
- OA enhances GPP and NCP and synergistic effects when combined with GW.
- DOC production decreased with OA and GW separately, but increased when combined.
- Climate change potentially increases the blue carbon service of C. nodosa populations.
Abstract
Ocean acidification (OA) and global warming (GW) drive a variety of responses in seagrasses that may modify their carbon metabolism, including the dissolved organic carbon (DOC) fluxes and the organic carbon stocks in upper sediments. In a 45-day full-factorial mesocosm experiment simulating forecasted CO2 and temperature increase in a Cymodocea nodosa community, we found that net community production (NCP) was higher under OA conditions, particularly when combined with warming (i.e., synergistic effect). Moreover, under OA conditions, an increase in aboveground biomass and photosynthetic shoot area was recorded. Interestingly, DOC fluxes were reduced when exposed to OA; however, an increase occurred when both factors acted together (i.e., antagonistic effect), which was attributable to increased DOC release by plants. Our results suggest that C. nodosa populations in temperate latitude may favor blue carbon service in future scenarios of OA and GW by increasing the NCP, the DOC export with lower labile:recalcitrant ratio, and accumulating more organic carbon in upper sediments. These findings offer additional arguments for the urgent need to protect and conserve this valuable ecosystem.
Continue reading ‘Ocean acidification and global warming may favor blue carbon service in a Cymodocea nodosa community by modifying carbon metabolism and dissolved organic carbon fluxes’
