Archive Page 39

Euromarine summer school: PulseOcean

Published 28 April 2025 Events Closed
Tags:

Dates: September 14-20, 2025
Venue: Ischia Marine Center- Stazione Zoologica Anton Dohrn, Ischia, Italy
Application deadline: May 26, 2025

More information:
https://drive.google.com/file/d/1bCfxPO2SMxCUUIZ2d7PfCKTijObZIbBj/view?usp=sharing
Application Form (A Google account is required to complete the form due to file upload
fields): https://forms.gle/bb8QitenPPmzdsJfA

We are thrilled to announce that the Euromarine Summer School PulseOcean is now open for applications! Tailored for PhD students and early-career researchers, this course combines lectures, fieldwork at the submarine CO2 vents in Ischia, and lab-based projects to provide a unique hands-on learning experience. You will learn and discuss topics including seawater chemistry and ecological methods, insights into blue carbon, AI-based image analysis, drone surveys and photogrammetry, and data science tools such as R and GitHub.

Continue reading ‘Euromarine summer school: PulseOcean’

Aragonite saturation state as an indicator for oyster habitat health in the Delaware Inland Bays

Published 28 April 2025 Science Closed
Tags: , ,

Aragonite and calcite are important nutrients for bivalves who biomineralize calcium carbonate in the water to form their outer shells. Ocean acidification can lead to a decrease in carbonate ions making forming these shells difficult. When the saturation state falls below a certain threshold (Ω < 1), it can cause oyster shells to dissolve. Therefore, measuring the Aragonite Saturation State yields crucial insight into the suitability of habitats to support oyster growth and productivity. Physiochemical water quality parameters were monitored from May to October 2020-2023. Using Seacarb, the aragonite-calcite saturation state was calculated using the following water quality parameters: temperature, salinity, alkalinity, and pH as inputs. Calcium hardness and dissolved oxygen was also measured to determine whether values were at a recommended threshold for shellfish hatcheries. There were fluctuations in the saturation states at each site, and oftentimes the values were undersaturated, especially during the cooling months. Spearman heatmaps demonstrate significant positive correlations between temperature and salinity (p = 0.46); pH and aragonite (p = 0.72); and alkalinity and aragonite (p = 0.51). This project aimed to determine the feasibility of different sites in supporting the establishment of oyster farms and oyster restoration efforts based on water quality conditions.

Continue reading ‘Aragonite saturation state as an indicator for oyster habitat health in the Delaware Inland Bays’

A psychologically wise intervention to inform relational organizing in the face of climate and ocean change

Published 28 April 2025 Science Closed
Tags:

Widespread climate action is broadly recognized as necessary to reduce climate change impacts on oceans (“ocean change”), but threats to ocean ecosystems are commonly perceived as distant, irrelevant, and unchangeable. Communicating about ocean change, therefore, requires message framing strategies targeting evidence-based psychological precursors to behavior. In a pre-registered case study of coastal visitors in Oregon, United States (n = 2414), we tested the influence of psychologically wise message about ocean change on climate action intentions. We primarily focused on influencing relational organizing: people’s willingness to encourage others to act. A behavior-specific message targeting relational organizing efficacy beliefs significantly but weakly increased intentions for relational organizing regarding ocean change compared to a control. Neither a connectedness to coast (place-based) message nor an ocean acidification (proximate threat-based) message had detectable effects on intentions. Our results suggest that targeting relational organizing efficacy may increase climate action intentions for the protection of coastal ecosystems.

Continue reading ‘A psychologically wise intervention to inform relational organizing in the face of climate and ocean change’

Ocean acidification shifts carbonate chemistry heterogeneity in molluscan respiratory microenvironments

Published 25 April 2025 Science Closed
Tags: , , , ,

Highlights

  • Seawater carbonate chemistry differs significantly within and outside the gill microenvironment of molluscs.
  • Ocean acidification increases the carbonate chemistry heterogeneity within and outside molluscs’ gill microenvironment.
  • The pCO2 level rises much more sharply within the gill microenvironment.
  • Carbonate chemistry heterogeneity exacerbates the impact of OA on molluscs.

Abstract

Ocean acidification (OA) poses a threat to marine calcifiers by modifying carbonate chemistry in ambient seawater, where localized fluctuations exert more immediate physiological impacts than bulk seawater changes. We investigated the heterogeneity of carbonate chemistry parameters (pH, DIC, pCO₂, TA-DIC) within the respiratory microenvironments (RE) of four molluscan species (Mytilus galloprovincialis, Haliotis discus hannai, Chlamys farreri, Crassostrea gigas) under ambient (pH 8.1) and OA conditions (pH 7.8). Our results demonstrated that regardless of bulk seawater pH, RE consistently exhibited significantly elevated dissolved inorganic carbon (DIC) and pCO₂ levels, coupled with reduced pH and lower TA-DIC ratios compared to bulk seawater (P < 0.05). Notably, H. discus hannai displayed the most pronounced RE modifications, with the highest DIC and pCO₂, alongside the lowest pH and TA-DIC values among studied species, revealing distinct interspecific variability. Acute OA exposure significantly increased pCO₂ heterogeneity (P < 0.05) while decreasing pH, DIC, and TA-DIC heterogeneity within the RE of three species (C. farreri, C. gigas, and H. discus hannai), suggesting suppressed CO₂ excretion capacity under rapid acidification stress. Prolonged OA exposure progressively enhanced spatial heterogeneity in DIC and pCO₂ levels, indicating physiological acclimation to facilitate metabolic CO₂ excretion. A critical finding was the accelerated pCO₂ increasing rate in RE compared to bulk seawater during OA stress, this steep elevation in pCO₂ level in RE may require extra-efforts to facilitate CO₂ excretion. These findings provide insights into the mechanistic links between OA-driven carbonate chemistry modifications and molluscan respiratory physiology, highlighting species-specific vulnerability patterns and adaptive responses.

Continue reading ‘Ocean acidification shifts carbonate chemistry heterogeneity in molluscan respiratory microenvironments’

Effects of ocean acidification on intestinal homeostasis and organismal performance in a marine bivalve: from microbial shifts to physiological suppression

Published 25 April 2025 Science Closed
Tags: , , , , , , , , , ,

Ocean acidification (OA) poses significant threats to marine calcifiers through multifaceted physiological disruptions. While bivalve mollusks are particularly vulnerable, the intestinal defense mechanisms against OA-induced stress remain poorly characterized. This study systematically investigated the intimate associations between the organismal physiological toxicity responses and intestinal homeostasis of Chlamys nobilis (C. nobilis) under simulated OA situations (pH 7.3-8.0) to reveal the potential physiological and biochemical damage. The results revealed that acidification stimulated pathogenic bacteria（Mycoplasma）colonization, disrupted microbiota homeostasis, and induced oxidative responses, thereby triggering intestinal inflammation and epithelial damage. Furthermore, the filtration rates and oxygen consumption rates of C. nobilis were significantly decreased in a pH-dependent manner across all the treatments, which might result from the intestinal dysfunction and the inhibition of acetylcholinesterase activities. These findings establish a link between OA-induced intestinal dysbiosis and organismal physiology, providing novel insights into the interplay between physiological performance and intestinal homeostasis under OA scenarios. The results advance our understanding of bivalve mollusk adaptation strategies and inform predictive models for its sustainability in acidifying marine ecosystems.

Continue reading ‘Effects of ocean acidification on intestinal homeostasis and organismal performance in a marine bivalve: from microbial shifts to physiological suppression’

Extreme compound events in the equatorial and South Atlantic

Published 24 April 2025 Science Closed
Tags: , , ,

The impacts of marine heatwaves (MHWs) on marine ecosystems can be amplified when combined with other extreme events. Here, we investigate the spatiotemporal evolution of compound events of MHW, high acidity and low chlorophyll in the equatorial and South Atlantic, using observation-based datasets and reanalysis products. We show that the frequency and intensity of these triple compound events under a fixed baseline have increased dramatically over the past two decades, peaking in the most recent years. We analyse the drivers of triple compound events for six regions and find that, for the Angola Front and Brazil-Malvinas Confluence regions, these events are associated with a poleward shift of the fronts. In the Agulhas Leakage region, an increase in warmer waters entering from the Indian Ocean leads to compound extremes. In the western equatorial and subtropical Atlantic, they are caused by changes in the air-sea heat fluxes, while in the eastern equatorial by a weakening of upwelling. In addition, triple compound events are widespread over the South Atlantic during El Niño events, which is important because MHWs can be predicted when associated with ENSO.

Continue reading ‘Extreme compound events in the equatorial and South Atlantic’

Riverine freshwater outflow enhanced ocean acidification in an urbanized subtropical estuary

Published 24 April 2025 Science Closed
Tags: , , ,

Highlights

  • Riverine carbonate input reduces buffering, amplifying acidification from CO₂.
  • Respiration of riverine organic matter intensifies acidification in low-salinities.
  • Organic matter-driven acidification affects the entire water column year-round.

Abstract

Ocean acidification poses a growing environmental threat to estuarine ecosystems. Most research has focused on bottom water acidification driven by eutrophication from riverine nutrient inputs. In contrast, the impacts of other riverine components in estuarine systems have received less attention. This study investigates the impacts of riverine carbonate and organic matter input on acidification in the Pearl River estuary (PRE), using field data from April 2015 to January 2016. The results show that DIC and TA in the PRE are primarily governed by river-ocean mixing, while their seasonal variations are largely influenced by changes in the freshwater end-member. Compared to the marine carbonate system, the riverine DIC:TA ratio is significantly higher. Riverine carbonate input weakens the estuarine buffering capacity during mixing, thereby amplifying acidification from atmospheric anthropogenic CO2. The pH reduction in the estuary due to anthropogenic CO2 intrusion reached a maximum of 0.15 units at a salinity of around 15, exceeding the 0.12 reduction at the seawater end. With the urbanization of the Pearl River Basin, the increased input of anthropogenic organic matter enhanced aerobic respiration in the estuary, releasing CO2 that may further intensify acidification. Unlike eutrophication-induced bottom acidification, which is closely associated with water column stratification and mainly occurs in the outer estuary during summer, organic matter-driven acidification is most pronounced in the upper estuary and affects the entire water column year-round. Moreover, it caused a maximum pH decline of up to 1.01 units in the PRE, surpassing that induced by eutrophication.

Continue reading ‘Riverine freshwater outflow enhanced ocean acidification in an urbanized subtropical estuary’

Evaluating the impact of ocean acidification on seafood – a global approach

Published 23 April 2025 Science Closed
Tags: , , , , , , , , ,

The quality of human life and food security are closely linked to the health of the ocean and the many goods and services it provides. However, the ocean is under cumulative stress from various human-driven pressures, leading to eutrophication, deoxygenation, loss of genetic biodiversity, contamination with emerging pollutants (e.g., microplastics and pesticides), and climate change (warming and ocean acidification). The effects of multiple ocean stressors and their interplay on marine life and ecosystems remain poorly understood. This underscores the urgent need for innovative science to resolve the complexity of the interplay of stressors and the resulting impacts. This paper reports findings from the Coordinated Research Project CRP K41018, a five-year program framed by the IAEA. The project was explicitly designed to advance Member States’ understanding of both quantitative and qualitative impacts of ocean acidification on key economically relevant seafood species across different world regions. Furthermore, based on different sensitivity baselines across species, it aimed at exploring adaptation pathways for aquaculture and food industries. As a result, Member States would have improved their comprehension of resilience building in specific local contexts (e.g., types of environments, geographical parameters, human dimension). In this context, it is essential to look for ocean solutions to mitigate adverse impacts on seafood and support adaptation strategies based on nature that can counteract stressors. It is concluded that there is great synergy in planning integrated mitigation and adaptation strategies to multiple stressors in marine ecosystems.

Continue reading ‘Evaluating the impact of ocean acidification on seafood – a global approach’

A simple CO2 enrichment incubator for investigating physiological responses of harmful algae to ocean acidification

Published 23 April 2025 Science Closed
Tags: , , , ,

A CO2 manipulation incubation system using off-the-shelf components was developed to study the effects of ocean acidification (OA) on marine microalgae. The system successfully monitored CO2 concentrations in real time at the desired levels. The incubation experiment was based on the IPCC’s CMIP6 worst-case scenario (SSP5-8.5), with elevated CO2 concentrations of up to 1000 ppm. Under these conditions, exposure to 1000 ppm CO2 significantly increased growth rate, cell diameter, and biovolume of harmful microalgae, Alexandrium tamiyavanichii. These effects were more pronounced, highlighting the potential for ocean acidification to exacerbate harmful algal blooms. The study also emphasized the importance of accounting for light attenuation in the incubation setup, revealing a 20% loss in light within culture bottles due to uneven light distribution. Correcting light intensity variations caused by the materials of the culture vessels was essential for unbiased growth assessments.

Continue reading ‘A simple CO2 enrichment incubator for investigating physiological responses of harmful algae to ocean acidification’

Cold spells, fresh waves, and the biogeochemical response in the North Atlantic cold anomaly region

Published 22 April 2025 Science Closed
Tags: , , ,

Regional effects of marine cold spells (MCS, periods of anomalous cooling), their impact on ecosystem biogeochemistry, and link to salinity extremes remain underexplored. A case in point is North Atlantic’s Cold Anomaly (CA) region (known as the “cold blob”), which hits record low temperatures during 2014–16 while most of the global ocean warmed. Using up to 42 years of observations, we characterize the CA as a manifestation of both MCS and Fresh Waves (FW, low salinity extremes) and analyze the surface biogeochemical response. We observe a quasiperiodic pattern of MCS from the 1980s and FW (at least) from the 1990s to early 2020s in the CA region with alternations from cool and freshwater to warm and saline conditions. Since 1990s, the CA region appears to be potentially undergoing MCS and FW compound events that are more frequent and prolonged but less intense than other North Atlantic areas. The 2014‐16 CA was among the most widespread and prolonged MCS and FW events associated with a deeper mixed layer and distinct biogeochemical signature, including elevated nutrients and oxygen, an overall increased chlorophyll‐a and intensified ocean acidification. These resultssuggest that MCS could mitigate certain climate change effects through cooling and enhanced productivity, while exacerbating others such as ocean acidification. We compare 2014–16 CA region effects with those of Pacific’s warm blob, identifying contrasting behaviors from physical processes to biogeochemical impacts and discussing a common atmospheric driver. Our findings emphasize the need to further study ecological responses to MCS in the North Atlantic.

Continue reading ‘Cold spells, fresh waves, and the biogeochemical response in the North Atlantic cold anomaly region’

Corals in ocean acidification and the role of calcium ion homeostasis to maintain calcification

Published 21 April 2025 Science Closed
Tags: , , ,

Coral calcification is essential to provide the structural foundation for coral reefs and is integral in supporting marine biodiversity reliant on reef ecosystems. The drivers for calcification in corals are undoubtedly highly complex and require several perspectives to identify vulnerabilities in the context of environmental change. Specifically, ocean acidification (OA) resulting from the rise of anthropogenic carbon dioxide (CO2) emissions poses a potential threat to the physiological mechanisms that drive calcification in corals. Therefore, this report goes beyond environmental seawater chemistry to examine the physiological mechanism of calcium ion homeostasis. Calcium’s role in calcification physiology is well established, but how calcium homeostasis could shift under acidification has little been considered a significant driver in reduced calcification. Calcium is potentially the most actively transported substrate in coral calcification, though in high chemical abundance in seawater, corals are likely utilizing the most energy to concentrate calcium at the site of calcification. We argue for increased consideration of the calcium ion in the context of OA when identifying sensitivities. The concepts proposed here are justified through a combination of results from novel RAMAN spectroscopy and molecular work that provides insight into shifts in calcium homeostasis when exposed to acidification. We speculate that future work incorporating methodologies considering calcium dynamics in OA could benefit by narrowing in on what physiological mechanisms are potentially vulnerable. It is imperative that we identify what drives lower calcification in corals under OA to inform efficient directives in identifying species sensitivities to future climate change.

Continue reading ‘Corals in ocean acidification and the role of calcium ion homeostasis to maintain calcification’

Ocean acidification research on ecologically and economically important sea cucumbers Is limited globally

Published 18 April 2025 Science Closed
Tags: , , , ,

Ocean acidification (OA) caused by increasing levels of partial pressure of carbon dioxide (CO2) and subsequent changes in seawater carbonate chemistry exerts knock-on effects on various calcifying organisms. However, little is known about the echinoderms (e.g., sea cucumbers) that are being overexploited globally for economic benefits. Most importantly, less is known about the impacts of OA on these organisms. Within this framework, the current study synthesized the available global data on the effects of OA on various sea cucumber species. Results indicate studies on OA impacts on sea cucumbers are limited to 10 species across eight countries globally, with Apostichopus japonicus being highly utilized under experimental conditions. Our results suggest that OA impacts reproduction, spawning events and sperm flagellar motility of sea cucumbers under low pH. This leads to the loss of energy allocations and reduction in somatic growth. Under low pH, the effects on Ca2+ and Mg2+ composition of calcareous ring and ossicles were species-specific and enzymatic activity was reduced. This study highlights the existing gaps that need to be addressed to prevent various knock-on effects of OA on sea cucumbers. This information is critical to managers and conservationists to manage the globally declining sea cucumber populations.

Continue reading ‘Ocean acidification research on ecologically and economically important sea cucumbers Is limited globally’

Long-term successional dynamics and response strategies of harmful algal blooms to environmental changes in Tolo Harbour

Published 18 April 2025 Science Closed
Tags: , , , , , , , , , , , , ,

Highlights

  • Long-term monitoring reveals significant shifts in harmful algal bloom species and toxin dynamics in Tolo Harbour.
  • Government actions reduced nutrient levels, but climate change and organic nutrients influenced HABs’ species succession.
  • Number of HABs decreased, meanwhile frequency and types of new toxin species emerged, highlighting complex ecological changes.
  • Balanced dual nutrient reduction strategies are essential for controlling HABs and restoring coastal ecosystem health.

ABSTRACT

The production and succession of harmful algae blooms (HABs) are attributed more to excessive nutrient concentrations and unbalanced nutrient stoichiometry than to other environmental drivers as the absence of long-term monitoring data. This study analyzed HABs succession patterns and key drivers in Tolo Harbour from 1986 to 2023, leveraging nearly 40 years of data. Effective governmental measures significantly improved water quality, with dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), 5-day biochemical oxygen demand (BOD5), and Escherichia coli (E. coli) concentrations decreasing by 53%, 80%, 45%, and 59%, respectively. Annual HABs events dropped from 28 to 3, and species diversity declined from 6 to 2. However, toxic species frequency rose from 21% to 46%. Dinoflagellates emerged as dominant initial species, with a shift in secondary dominance from diatoms to ochrophytes and toxin types from diarrhetic shellfish poisoning (DSP) to hemolytic toxins (HT). These shifts likely result from combined human and natural influences. Model simulations confirmed that red tide outbreaks, species succession, and shifts in toxin types were driven by declining pH, rising temperatures, unbalanced nitrogen-phosphorus ratios, organic nutrient increases, and algal antagonism. The study emphasizes the importance of the dual reduction of both DIN and DIP, meanwhile inorganic and organic nutrients, suggesting that overly focusing on or distract from one nutrient (e.g., DIP or DON) could lead to unintended ecological consequences, like the proliferation of rare and toxic species. We highlight the combined impacts of climate change (warming and ocean acidification) and anthropogenic activities (nutrient pollution and eutrophication) on HABs, particularly the number and toxin production. This research links policy changes to HAB dynamics, offering strategic recommendations for managing red tides and contribute novel perspectives on the impact of nutrient reduction in comparable bay ecosystems.

Continue reading ‘Long-term successional dynamics and response strategies of harmful algal blooms to environmental changes in Tolo Harbour’

Modeling terrestrial dissolved organic carbon and its effect on the carbonate system in the Sunda Shelf seas, Southeast Asia

Published 17 April 2025 Science Closed
Tags: , , , , ,

Abstract

The flux of dissolved organic carbon (DOC) from land to sea is an important transfer within the global carbon cycle. The biogeochemical fate of this terrestrial DOC (tDOC) remains poorly understood and is usually neglected in ocean models. Southeast Asia accounts for around 10% of global tDOC flux, mostly from tropical peatland-draining rivers discharging onto the Sunda Shelf. We developed a new light-driven parameterization of tDOC remineralization that accounts for photochemical, microbial, and interactive photochemical–microbial degradation, and simulated the transport and remineralization of tDOC through the Sunda Shelf seas using the regional 3D hydrodynamical HAMSOM and biogeochemical ECOHAM models (only for the carbonate system). Our realistic hindcast simulations for 1958–2022 show that about 50% of riverine tDOC is remineralized before leaving the shelf. This lowers seawater pH across the entire inner Sunda Shelf by an average of 0.005 (by up to 0.05 in the Malacca Strait). Correspondingly, seawater pCO2 is raised, increasing yearly CO2 outgassing from the shelf by 19% (3.1 Tg C yr−1, 0.14 mol m−2 yr−1) during 2013–2022. Even regional ocean acidification trends increase, because river discharge and tDOC flux increase. Our model reveals large spatial variability with greatest inputs and remineralization of tDOC close to major peatlands, especially off Sumatra and Borneo. The interannual variability in tDOC input and the monsoonal current reversal lead to strong temporal variability in carbonate system parameters in these areas. Our results highlight the importance of representing tDOC in ocean models, and reveal the fate of tropical peatland tDOC.

Key Points

  • We modeled terrestrial dissolved organic carbon (tDOC) using a new scheme for photo-, bio-, and interactive photo-bio-degradation
  • TDOC input to the Sunda Shelf in 2013–2022 is 15.9 Tg C yr−1. 50% is remineralized on the shelf, 28% directly exported to Indian Ocean
  • This drives shelf-wide outgassing of 3.1 Tg C yr−1 in 2013–2022, lowers pH and aragonite saturation, increases ocean acidification trends

Plain Language Summary

The transport of terrestrial dissolved organic carbon (tDOC) from land to sea via rivers is an important part within the global carbon cycle. The majority of this tDOC is remineralized by sunlight and marine bacteria, which produces CO2 leading to ocean acidification and CO2 outgassing into the atmosphere. The degradation process is poorly understood, usually neglected in ocean models. Southeast Asia accounts for around 10% of global tDOC flux, mostly from rivers with peatland areas in their catchment. We developed an equation of tDOC remineralization that depends on sunlight and accounts for photochemical, microbial, and interactive photochemical–microbial degradation. With this, we simulated the fate of tDOC using a 3D computer model system for the Southeast Asian region. Our realistic results for 1958–2022 show: 50% of the tDOC is remineralized before leaving the Sunda Shelf. As a result, the shelf water acidifies and emits more CO2 to the atmosphere. Because of increasing river freshwater runoff (from climate change), more tDOC is transported in time into the sea and more is remineralized, increasing the ocean acidification. This happens mostly in coastal seas close to rivers with much peatland in their catchment. This is harmful for calcifying marine organisms like corals.

Continue reading ‘Modeling terrestrial dissolved organic carbon and its effect on the carbonate system in the Sunda Shelf seas, Southeast Asia’

Sonardyne integrates -4H-JENA sensor into ADCP for ocean acidification research

Published 17 April 2025 Media coverage Closed
Tags:

Underwater technology manufacturer Sonardyne International Ltd has integrated a CONTROS HydroC dissolved CO2 sensor from -4H-JENA engineering into its Origin 600 ADCP (Acoustic Doppler Current Profiler), unlocking new capabilities for marine research into ocean acidification.

The combined solution enables precise, real-time monitoring of dissolved carbon dioxide levels alongside detailed current profiling, providing insights into the impacts of rising CO2 concentrations on marine ecosystems and biodiversity.

The CONTROS HydroC dissolved CO2 sensor from -4H-JENA engineering is designed specifically for accurate and reliable measurement of dissolved carbon dioxide in marine environments. Such sensors are essential tools for understanding ocean acidification. The HydroC sensor integrates with Sonardyne’s Origin 600 through either direct connection to the ADCP’s external sensor port or via the versatile Origin E-Mux multiplexer, which supports up to four external sensors simultaneously and extends power supply capability for longer deployments.

…

Continue reading ‘Sonardyne integrates -4H-JENA sensor into ADCP for ocean acidification research’

Record of foraminifera test composition throughout the Phanerozoic

Published 17 April 2025 Science Closed
Tags: , , , ,

Marine calcifiers produce calcareous structures (e.g. shells, skeletons or tests) and are therefore sensitive to ocean chemistry. Nevertheless, the long-term evolutionary consequences of marine carbonate changes are not well understood. This article compares calcareous and non-calcareous responses to ocean chemistry changes throughout the Phanerozoic Eon (541 million years ago to present). To accomplish this, we calculated proportional wall-type diversity, origination rates and extinction rates for 2282 benthic foraminiferal genera. Calcareous origination and extinction rates fluctuated throughout the Palaeozoic Era (541–251.9 million years ago), but during the Mesozoic Era (251.9–66 million years ago), calcareous origination and extinction rates stabilized following the evolution of pelagic calcifiers. Despite variations in Cenozoic Era (66–0 million years ago) foraminifera diversity, calcareous wall types maintained around 77% proportional diversity. Although calcareous wall-type extinction rates decline during the Mesozoic and Cenozoic, Phanerozoic foraminifera wall-type changes during individual events are largely contingent upon contemporaneous conditions rather than overarching trends. Of the Big Five mass extinction events, calcareous wall-type proportions only decreased at the end-Permian (73% to 26% diversity) and end-Triassic (56% to 50% diversity). These results suggest long-term ocean chemistry changes were not the main driver of foraminiferal wall-type diversity through time.

Continue reading ‘Record of foraminifera test composition throughout the Phanerozoic’

The Piver’s Island coastal observatory – a decade of weekly+ observations reveal the press and pulse of a changing temperate coastal marine system

Published 16 April 2025 Science Closed
Tags: , ,

Historically, oceanographic time-series have focused on long-term measurements of large open ocean gyres; yet, the coastal oceans, with their high productivity, tidal impacts, human feedbacks, and land-sea coupling, represent critical regions for predicting ocean dynamics and biogeochemistry under global change. The Piver’s Island Coastal Observatory (PICO) time-series, located in the second largest estuarine system on the US East Coast (Albemarle-Pamlico Sound), comprises more than a decade of weekly (or more frequent) measurements of core physical, chemical, and biological oceanographic variables. PICO provides insight into a coastal, mesotrophic ecosystem in an ecologically-diverse and biochemically-active region impacted by global change. Here, we report on a decade of observations focusing on pulse and press ecosystem changes. We observe strong mean annual cycles in environmental variables including temperature (10.1-28.9°C), pH (7.89-8.12), dissolved inorganic carbon (DIC: 1965 – 2088 µM), chlorophyll (2.54-5.77 mg Chl m-3), upon which are layered episodic disturbances (e.g., tropical cyclones) that dramatically and persistently (>1 month) impact this ecosystem. Among other variables, long term trends in pH (-0.004 ± 0.001 y-1; p<0.01), DIC (-9.8 ± 1.5 µM y -1; p<0.01) and chlorophyll (-0.17 ± 0.02 µg L-1 y-1; p<0.01) are exceeding those observed in the open ocean, suggesting an ecosystem in flux. These analyses provide a benchmark for future studies of the impact of changing climate and oceanographic climatology; further research will use this long-term research to developed targeted sampling and experimental manipulations to better understand ecosystem structure and function.

Continue reading ‘The Piver’s Island coastal observatory – a decade of weekly+ observations reveal the press and pulse of a changing temperate coastal marine system’

Quantitative reconstruction of intermediate water pH in the South China Sea based on branched tetraether lipids

Published 16 April 2025 Science Closed
Tags: , , ,

The geochemical proxy of ocean pH is crucial for understanding the dynamics of ancient ocean carbon reservoirs. This study employs the cyclization index of branched glycerol dialkyl glycerol tetraether compounds (brGDGTs), widely used in terrestrial environments for paleo-pH reconstruction, to investigate the intermediate water pH in the South China Sea. The South China Sea, a semi-enclosed marginal sea in the western Pacific, serves as the study area. By collecting data including global soil datasets, subtropical soil data, samples with water depths less than 50 meters in the northern South China Sea, surface sediment samples in the South China Sea, and brGDGTs data from rock cores in the northern South China Sea, significant differences were found in the composition of brGDGTs in marine sediments compared to those in soils. This proves the in-situ self generation viewpoint of brGDGT in the ocean, mainly generated in the middle water column, providing a basis for reconstructing ocean acidification. The research materials for establishing a global formula include deep-sea sediment samples from the South China Sea, Western Pacific, Southeast Pacific, Northeast Atlantic, and Southwest Atlantic, all of which were collected at depths of over 300 meters to avoid terrestrial influence. Lipids were extracted using a modified Bligh-Dyer method and analyzed using high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry(HPLC-APCI-MS). A positive correlation between brGDGTs indices (CBT’ and #Ringstetra)and seawater pH was established, allowing for the development of empirical formulas for reconstructing ancient midwater seawater pH. Utilizing published brGDGTs data from Holocene sediments in the northern South China Sea, the reconstructed pH values indicate a maximum of approximately 7.89 around 6.5 ka and a minimum of about 7.72 around 1.5 ka. The study validates that brGDGTs in deep-sea sediments are of marine origin. This research demonstrates that brGDGTs in marine sediments are autochthonous and can be employed to reconstruct intermediate water pH, providing significant insights into ocean acidification history.

Continue reading ‘Quantitative reconstruction of intermediate water pH in the South China Sea based on branched tetraether lipids’

Calcification of planktonic foraminifer Neogloboquadrina dutertrei and its indicative significance for ocean acidification

Published 16 April 2025 Science Closed
Tags: , , , , ,

Planktonic foraminifera are widespread calcifying protozoa and represent a primary source of marine biogenic calcium carbonate. Elucidating the mechanisms underlying the calcification processes of planktonic foraminifera holds significant importance for understanding the marine biological pump and carbon cycling.

The present study investigated the controlling mechanisms of calcification in modern planktonic foraminifer Neogloboquadrina dutertrei by analyzing the foraminiferal shell weight data from 92 sets of surface sediments from different ocean areas, including the eastern tropical Indian, the western tropical Pacific, the eastern tropical Pacific, and the western tropical Atlantic. First, this study reveals that deep-ocean carbonate dissolution, which is related to deep-ocean carbonate ion saturation state (Δ[CO32-]), is the dominant factor influencing the shell weight of N. dutertrei in surface sediments. Then, by correcting the dissolution effect on the shell weight of N. dutertrei, we estimated the initial shell weight from which to assess secular changes in the degree of calcification of N. dutertrei. The initial shell weight results suggest that the calcification of N.dutertrei is mainly controlled by seawater carbonate system parameters such as pH, carbonate ion concentration ([CO32-]), and carbon dioxide concentration (pCO2). Calcification of N. dutertrei would decrease with ocean acidification.

Furthermore, we reconstructed initial shell weight of N.dutertrei at sites KX97322-4 and U1490 in the western tropical Pacific to evaluate the response of N. dutertrei calcification to climate changes over glacial-interglacial time scales. Calcification of N. dutertrei in the western tropical Pacific has increased during glacial periods in response to lower atmospheric pCO2 since 800 ka, confirming the dominant influence of ocean acidification on N. dutertrei calcification. We suggest that the shell weight of specific planktonic foraminiferal species may serve as a potential proxy for past seawater carbonate system reconstructions.

Continue reading ‘Calcification of planktonic foraminifer Neogloboquadrina dutertrei and its indicative significance for ocean acidification’

An improved long-term high-resolution surface pCO2 data product for the Indian Ocean using machine learning

Published 16 April 2025 Science Closed
Tags: , , ,

Accurate estimation of surface ocean pCO2 is crucial for understanding the ocean’s role in the global carbon cycle and its response to climate change. In this study, we employ a machine learning algorithm to correct the deviations in high-resolution (1/12°) model simulations of surface pCO2 from the INCOIS-BIO-ROMS model (pCO2model) for the period 1980–2019, using available observations (pCO2obs). We train the XGBoost model to generate spatio-temporal deviations (pCO2obs − pCO2model) of pCO2model. The interannually and climatologically varying deviations are then added back to the original model separately, which results in an improved surface pCO2 data product. A comparison of our surface pCO2 data product with moored observations, gridded SOCAT, CMEMS-LSCE-FFNN, and OceanSODA demonstrates an improvement by approximately 40% ± 3.31% in RMSE. Further analysis reveals that adding climatological deviations to pCO2model results in greater improvements than adding interannual deviations. This analysis underscores the ability of machine learning algorithms to enhance the accuracy of model-simulated surface pCO2 outputs.

Continue reading ‘An improved long-term high-resolution surface pCO2 data product for the Indian Ocean using machine learning’

Subscribe

Search

  • Reset

OA-ICC Highlights

Resources