Our study highlights the importance of understanding the future changes in dimethyl-sulfide (DMS), the largest natural sulfur source, in the context of ocean acidification driven by elevated CO2 levels. We found a strong negative correlation (R2 = 0.89) between the partial pressure of carbon dioxide (pCO2) and sea-surface DMS concentrations based on global observational datasets, not adequately captured by the Coupled Model Intercomparison Project Phase 6 (CMIP6) Earth System Models (ESMs). Using this relationship, we refined projections of future sea-surface DMS concentrations in CMIP6 ESMs. Our study reveals a decrease in global sea-surface DMS concentrations and the associated aerosol radiative forcing compared to ESMs’ results. These reductions represent ~9.5% and 11.1% of the radiative forcings resulting from aerosol radiation and cloud interactions in 2100 reported by the Intergovernmental Panel on Climate Change Sixth Assessment Report. Thus, future climate projections should account for the climate implications of changes in DMS production due to ocean acidification.
Continue reading ‘Changes in global DMS production driven by increased CO2 levels and its impact on radiative forcing’Archive Page 88
Changes in global DMS production driven by increased CO2 levels and its impact on radiative forcing
Published 5 February 2024 Science ClosedTags: chemistry, globalmodeling, modeling
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The great catastrophe: causes of the Permo-Triassic marine mass extinction
Published 2 February 2024 Science ClosedTags: paleo, review
The marine losses during the Permo-Triassic mass extinction were the worst ever experienced. All groups were badly affected, especially amongst the benthos (e.g. brachiopods, corals, bryozoans, foraminifers, ostracods). Planktonic populations underwent a fundamental change with eukaryotic algae being replaced by nitrogen-fixing bacteria, green-sulphur bacteria, sulphate-reducing bacteria and prasinophytes. Detailed studies of boundary sections, especially those in South China, have resolved the crisis to a ∼55 kyr interval straddling the Permo-Triassic boundary. Many of the losses occur at the beginning and end of this interval painting a picture of a two-phase extinction. Improved knowledge of the extinction has been supported by numerous geochemical studies that allow diverse proposed extinction mechanisms to be studied. A transition from oxygenated to anoxic-euxinic conditions is seen in most sections globally, although the intensity and timing shows regional variability. Decreased ocean ventilation coincides with rapidly rising temperatures and many extinction scenarios attribute the losses to both anoxia and high temperatures. Other kill mechanisms include ocean acidification for which there is conflicting support from geochemical proxies and, even less likely, siltation (burial under a massive influx of terrigenous sediment) which lacks substantive sedimentological evidence. The ultimate driver of the catastrophic changes at the end of the Permian was likely Siberian Trap eruptions and their associated carbon dioxide emissions with consequences such as warming, ocean stagnation and acidification. Volcanic winter episodes stemming from Siberian volcanism have also been linked to the crisis, but the short-term nature of these episodes (<decades) and the overwhelming evidence for rapid warming during the crisis makes this an unlikely cause. Finally, whilst the extinction is well studied in equatorial latitudes, a different history is found in northern Boreal latitudes including an earlier crisis which merits further study in order to fully understand the course and cause of the Permo-Triassic extinctions.
Continue reading ‘The great catastrophe: causes of the Permo-Triassic marine mass extinction’Transport of anthropogenic carbon from the Antarctic shelf to deep Southern Ocean triggers acidification
Published 2 February 2024 Science ClosedTags: Antarctic, biogeochemistry, chemistry
Abstract
Flow of dense shelf water provide an efficient mechanism for pumping CO2 to the deep ocean along the continental shelf slope, particularly around the Antarctic bottom water (AABW) formation areas where much of the global bottom water is formed. However, the contribution of the formation of AABW to sequestering anthropogenic carbon (Cant) and its consequences remain unclear. Here, we show prominent transport of Cant (25.0 ± 4.7 Tg C yr−1) into the deep ocean (>2,000 m) in four AABW formation regions around Antarctica based on an integrated observational data set (1974–2018). This maintains a lower Cant in the upper waters than that of other open oceans to sustain a stronger CO2 uptake capacity (16.9 ± 3.8 Tg C yr−1). Nevertheless, the accumulation of Cant can further trigger acidification of AABW at a rate of −0.0006 ± 0.0001 pH unit yr−1. Our findings elucidate the prominent role of AABW in controlling the Southern Ocean carbon uptake and storage to mitigate climate change, whereas its side effects (e.g., acidification) could also spread to other ocean basins via the global ocean conveyor belt.
Key Points
- We show evidence for the accumulation of Cant along the Antarctic shelf-slope into the deep ocean
- The process of AABW formation drives Cant downward transport at 25.0 ± 4.7 Tg C yr−1, sustaining the CO2 uptake in the surface ocean
- This further triggers acidification of AABW at a rate of −0.0006 ± 0.0001 pH unit yr−1, which is faster than in other deep oceans
Physiological responses of Caulerpa spp. (with different dissolved inorganic carbon physiologies) to ocean acidification
Published 1 February 2024 Science ClosedTags: algae, biological response, growth, laboratory, photosynthesis, physiology, primary production, South Pacific
Caulerpa is a widely distributed genus of chlorophytes (green macroalgae) which are important for their dietary, social and coastal ecosystem value. Ocean acidification (OA) threatens the future of marine ecosystems, favouring macroalgal species that could benefit from increased seawater carbon dioxide (CO2) concentrations. Most macroalgae species possess CO2 concentrating mechanisms (CCMs) that allow active uptake of bicarbonate (HCO3−). Those species without CCMs are restricted to using CO2, which is currently the least abundant species of dissolved inorganic carbon (DIC) in seawater. Thus, macroalgae without CCMs are predicted to be likely benefit from OA. Caulerpa is one of the rare few genera that have species both with and without CCMs. The two most common Caulerpa species in New Zealand are C. geminata (possesses a CCM) and C. brownii (non-CCM). We investigated the responses of growth, photo-physiology and DIC utilisation of C. geminata and C. brownii to four mean seawater pH treatments (8.03, 7.93, 7.83 and 7.63) that correspond to changes in pH driven by increases in pCO2 simulating future OA. There was a tendency for the mean growth rates for C. brownii (non-CCM) to increase under lower pH, and the growth rates of C. geminata (CCM) to decline with lower pH, although this was not statistically significant. However, this is likely because variability in growth rates also increased as seawater pH declined. There were few other differences in physiology of both species with pH, although there was tendency for greater preference for CO2 over HCO3− uptake in the CCM species with declining seawater pH. This study demonstrates that DIC-use alone does not predict macroalgal responses to OA.
Continue reading ‘Physiological responses of Caulerpa spp. (with different dissolved inorganic carbon physiologies) to ocean acidification’Habitat sensitivity in the West African coastal area: inferences and implications for regional adaptations to climate change and ocean acidification
Published 1 February 2024 Science ClosedTags: chemistry, field, North Atlantic, South Atlantic
This study focuses on assessing coastal vulnerability and habitat sensitivity along the West African coast by delineating hotspots based on surface temperature, pH, chlorophyll-a, particulate organic carbon, and carbonate concentrations between 2018 and 2023 depending on data availability. Initial exploration of these variables revealed two distinct focal points i.e., the Togo-Nigerian coastal stretch and the stretch from Sierra Leone to Mauritania. Lower pH trends (acidification) in surface waters were observed off the West African coast, particularly in areas around the south-south Niger Delta in Nigeria and the coastal regions of Guinea and Guinea Bissau. Sea surface temperature analysis revealed highest temperatures (27–30°C) within Nigeria to Guinea coastal stretch, intermediate temperatures (24–27°C) within the Guinea Bissau and Senegal coastal stretch, and the lowest temperatures off the coast of Mauritania. Furthermore, correlation analysis between sea surface temperature and calcite concentration in the Mauritania-Senegal hotspot, as well as between overland runoff and particulate organic carbon in the Togo-Nigeria hotspot, revealed strong positive associations (r>0.60) and considerable predictive variability (R2 ≈ 0.40). From the habitat sensitivity analysis, certain regions, including Cape Verde, Côte d’Ivoire, Nigeria, Senegal, and Sierra Leone, exhibited high sensitivity due to environmental challenges and strong human dependence on coastal resources. Conversely, Gambia, Guinea, Guinea-Bissau, Liberia, and Togo displayed lower sensitivity, influenced by geographical-related factors (e.g. coastal layout, topography, etc.) and current levels of economic development (relatively lower industrialization levels). Regional pH variations in West African coastal waters have profound implications for ecosystems, fisheries, and communities. Addressing these challenges requires collaborative regional policies to safeguard shared marine resources. These findings underscore the link between ecosystem health, socioeconomics, and the need for integrated coastal management and ongoing research to support effective conservation.
Continue reading ‘Habitat sensitivity in the West African coastal area: inferences and implications for regional adaptations to climate change and ocean acidification’Answer to high ocean acidity may lie in carbon transfer from wetlands
Published 1 February 2024 Media coverage ClosedThe rise in carbon dioxide levels in our atmosphere is also helping to acidify our oceans even further, resulting in more dire consequences for aquatic ecosystems and the planet. But, our wetlands may have the solution
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Scientists are looking for solutions to remove greenhouse gases trapped in our atmosphere, and one idea may lie in the wetlands.
Stopping fossil fuel emissions will not be enough to limit global warming to a 1.5°C to 2°C rise during this century, according to Kevin Kroeger, United States Geological Survey (USGS) research chemist.
Similar to how plants in wetlands and other landscapes work, oceans ingest carbon dioxide from the atmosphere directly, like a sponge, and that form of carbon is acidic. While that process can regulate the amount of CO2 in Earth’s atmosphere, the oceans then bear the brunt of the effects. The result sees significant and negative impacts on coral reefs, shellfish and other aquatic species.
Not every type of carbon is acidic, however. Some of it that transitions from wetlands to oceans is in the form of bicarbonate, which can help offset acidity, according to the USGS.
(USGS)
“We’ve been looking at coastal wetlands, salt marshes, mangroves and the carbon cycling in those ecosystems as one opportunity for removing greenhouse gases from the atmosphere,” Kroeger said in a recent interview with The Weather Network.
Continue reading ‘Answer to high ocean acidity may lie in carbon transfer from wetlands’
Did you know that our oceans play a vital role in the fight against climate change? As carbon storage takes an increasingly important role in climate change mitigation, the term blue carbon has been gaining prominence. But what exactly is it and what role does it play in the context of climate change?
What Is Blue Carbon?
Blue carbon refers to carbon captured by marine ecosystems. It is well known that carbon dioxide (CO2) is one of the most important greenhouse gasses (GHGs) and a main contributor to climate change. As the primary GHG emitted through human activities, reducing the concentration of CO2 in the atmosphere is paramount to slowing down climate change. While the most sustainable way to do this is by reducing our effective CO2 emissions, carbon storage plays an important role in removing the CO2 that has already been released into the atmosphere.
Carbon storage, also referred to as carbon sequestration, describes the process by which carbon is removed from the atmosphere and stored in a so-called carbon pool. While this process can be imitated or enhanced through technology, it occurs in nature all the time – for example in our oceans and the coastal vegetation surrounding them.
Continue reading ‘Explainer: what is blue carbon?’Seasonal resilience of temperate estuarine fish in response to climate change
Published 31 January 2024 Science ClosedTags: biological response, BRcommunity, community composition, fish, modeling, North Pacific, otherprocess, performance, regionalmodeling
Highlights
- The suitability of fish habitat is threatened by falling pH, especially in spring.
- Seasonality provides resilience against climate change for estuarine fish and assemblages.
- Centroids respond by shifting northeast in spring and southeast in autumn.
- Support for estuary ecosystem management under climate change is offered.
Abstract
To date, the intricacies and efficacy of how periodic seasonal environmental fluctuations affect fish populations in biogeography in the context of profound climate change remain to be elucidated. Collected monitoring data on fish resources in the temperate estuary provide an excellent opportunity to assess the effects of seasonal environmental fluctuations on populations and functional assemblages under climate change. We first developed a framework for predicting habitat suitability under different climate change scenarios (SSP1-2.6 and SSP5-8.5) for 12 fish populations in the Yangtze estuary by examining the seasonal environmental affinities of temperate estuarine fishes. We then summarized the multidimensional habitat suitability responses (HSRs) of populations and functional assemblages and discussed the possible drivers and mechanisms underlying these changes. The results suggest that the acidity of the Yangtze estuary may decline in the future as the climate warms, endangering the ecosystem that many fish species depend on. Prospective climate change may have an impact on fish population HSRs through redistribution, area changes, and centroid migration of suitable habitats; nevertheless, affinity for environmental factors may be limited to distinguishing patterns of population response in the spring. Fish (5 populations) and functional assemblages (11 assemblages) may exhibit robust adaptations or non-adaptations to climate change when seasons change, given their suitable habitat area. Furthermore, projections indicate that the majority of fish habitat centroids exhibit seasonal responses, migrating northeast in the spring and southeast in the autumn. By decentralizing climate risk to seasonal scales, seasonal resilience in the multidimensional HSRs of several fish populations (5/12) and their functional assemblages (11/16) is revealed for the first time. Efforts to mitigate climate risks and safeguard resources should take these seasonal forecasts and indicative information into account.
Continue reading ‘Seasonal resilience of temperate estuarine fish in response to climate change’A synthesis of ocean total alkalinity and dissolved inorganic carbon measurements from 1993 to 2022: the SNAPO-CO2-v1 dataset (update)
Published 31 January 2024 Science ClosedTags: Antarctic, chemistry, field, Indian, Mediterranean, North Atlantic, North Pacific, South Atlantic, South Pacific
Total alkalinity (AT) and dissolved inorganic carbon (CT) in the oceans are important properties with respect to understanding the ocean carbon cycle and its link to global change (ocean carbon sinks and sources, ocean acidification) and ultimately finding carbon-based solutions or mitigation procedures (marine carbon removal). We present a database of more than 44 400 AT and CT observations along with basic ancillary data (spatiotemporal location, depth, temperature and salinity) from various ocean regions obtained, mainly in the framework of French projects, since 1993. This includes both surface and water column data acquired in the open ocean, coastal zones and in the Mediterranean Sea and either from time series or dedicated one-off cruises. Most AT and CT data in this synthesis were measured from discrete samples using the same closed-cell potentiometric titration calibrated with Certified Reference Material, with an overall accuracy of ±4 µmol kg−1 for both AT and CT. The data are provided in two separate datasets – for the Global Ocean and the Mediterranean Sea (https://doi.org/10.17882/95414, Metzl et al., 2023), respectively – that offer a direct use for regional or global purposes, e.g., AT–salinity relationships, long-term CT estimates, and constraint and validation of diagnostic CT and AT reconstructed fields or ocean carbon and coupled climate–carbon models simulations as well as data derived from Biogeochemical-Argo (BGC-Argo) floats. When associated with other properties, these data can also be used to calculate pH, the fugacity of CO2 (fCO2) and other carbon system properties to derive ocean acidification rates or air–sea CO2 fluxes.
Continue reading ‘A synthesis of ocean total alkalinity and dissolved inorganic carbon measurements from 1993 to 2022: the SNAPO-CO2-v1 dataset (update)’Study of the combined effect of microplastics and global warming factors on marine zooplankton
Published 31 January 2024 Science ClosedTags: biological response, echinoderms, laboratory, morphology, multiple factors, North Atlantic, physiology, temperature, toxicants
Microplastics (MP) and agrochemicals are frequently found as contaminants in the marine environment. Furthermore, the process of ocean acidification (OA) and ocean warming (OW) are projected to have indirect effects on organisms, as they can modify the availability and potentially increase the toxicity of various pollutants. The objective of this study is to evaluate if global change conditions (pH = 7.8 and temperature of 24ºC) could modify the toxicity of the combination of MP and chlorpyrifos (CPF) in Paracentrotus lividus larvae. Morphological, physiological, and biochemical responses were measured in P. lividus larvae resulting from embryos that had been exposed to these stressors at two different concentrations of CPF, 60 and 250 µg/L. The concentration of MP was fixed at 3000 particles (P)/mL. Growth and morphology of pluteus larvae were determined after 48 h of incubation. At low CPF doses, larval growth and morphology were affected as the number of stressors increased. Treatments that included thermal stress showed that larvae reared at 24ºC are not achieving their maximum growth potential when growth is expressed in Degree-Days (DD). At the morphological level, sea urchin larvae exhibit a trapezoidal shape instead of the typical triangular form, according to the different morphological measurements. Temperature was found to play a key role in the regulation of several enzymatic activities. Acetylcholinesterase (AChE) was found to have a temperature-dependent inhibition. Glutathione–S–transferase (GST) was induced in the presence of CPF, and inhibited as environmental stress factors increase. Glutathione reductase (GRx) activity increased when exposed to thermal stress, but it may also be inhibited by the interaction of various environmental stressors. At high CPF concentrations, the multi-factor treatments were strongly affected, both at growth and morphological level. The treatments that included global change conditions resulted in a significant reduction of 75% in larval size. Moreover, the parameters that were measured to detect larval deformities were also clearly affected. Biomarkers were mostly inhibited at high CPF concentrations, with almost no significant differences between treatments. Overall, in this study it was demonstrated that global climate change conditions influenced the impact of pollutants in marine biota, increasing the sensitivity of sea urchin embryos. This effect is detectable not only at the morphological level but also at the biochemical level, clearly affecting the fitness of organisms that are exposed to multiple stressors in their habitats.
Continue reading ‘Study of the combined effect of microplastics and global warming factors on marine zooplankton’Atmospheric CO2 estimates for the Late Oligocene and Early Miocene using multi-species cross-calibrations of boron isotopes
Published 31 January 2024 Science ClosedTags: biological response, BRcommunity, chemistry, methods, paleo, protists, sediment
Abstract
The boron isotope (δ11B) proxy for seawater pH is a tried and tested means to reconstruct atmospheric CO2 in the geologic past, but uncertainty remains over how to treat species-specific calibrations that link foraminiferal δ11B to pH estimates prior to 22 My. In addition, no δ11B-based reconstructions of atmospheric CO2 exist for wide swaths of the Oligocene (33–23 Ma), and large variability in CO2 reconstructions during this epoch based on other proxy evidence leaves climate evolution during this period relatively unconstrained. To add to our understanding of Oligocene and early Miocene climate, we generated new atmospheric CO2 estimates from new δ11B data from fossil shells of surface-dwelling planktic foraminifera from the mid-Oligocene to early Miocene (∼28–18 Ma). We estimate atmospheric CO2 of ∼680 ppm for the mid-Oligocene, which then evolves to fluctuate between ∼500–570 ppm during the late Oligocene and between ∼420–700 ppm in the early Miocene. These estimates tend to trend higher than Oligo-Miocene CO2 estimates from other proxies, although we observe good proxy agreement in the late Oligocene. Reconstructions of CO2 fall lower than estimates from paleoclimate model simulations in the early Miocene and mid Oligocene, which indicates that more proxy and/or model refinement is needed for these periods. Our species cross-calibrations, assessing δ11B, Mg/Ca, δ18O, and δ13C, are able to pinpoint and evaluate small differences in the geochemistry of surface-dwelling planktic foraminifera, lending confidence to paleoceanographers applying this approach even further back in time.
Key points:
- We measure δ11B on multiple species of planktic foraminifera to generate new CO2 reconstructions for the late Oligocene and early Miocene
- Using a novel cross-calibration approach, we reconstruct CO2 of 500–680 ppm for the mid-late Oligocene and 420–700 ppm for the early Miocene
- Mean CO2 values tend to trend higher than other proxy estimates, but generally lower than paleoclimate model simulations
Hydrographical studies in the nearshore seawaters of the Red Sea coast of Al-Hodeida city, Yemen
Published 30 January 2024 Science ClosedTags: chemistry, field, Red Sea
Hydrographic studies of nearshore seawaters are important because they are sensitive to both natural and human influences. The hydrographic study is very important for nearshore waters because it is very sensitive to natural and human influences. In this research, an attempt was made to study the hydrographic properties of the nearshore waters of the Red Sea coast of Hodeida city, Yemen. During the period from December 2021 to June 2022, to represent the two seasons of winter and summer. The water temperatures ranged from 30 to 34.5 °C, salinity fluctuated from 39.3 to 42.4 psu, pH varied from 7.9 to 8.2 and dissolved oxygen ranged from 4.88 to 8.54 mg/l. The higher values of temperature and salinity were recorded during summer season. In contrast, an increase in pH and dissolved oxygen were observed during winter season. The present study confirmed that salinity has a negative correlation with pH and dissolved oxygen although it was not significant and also it showed significant positive correlation between pH and dissolved oxygen (0.828). The hydrographical parameters showed significant spatial and temporal variations. The present baseline information is useful for the further ecological monitoring and assessment along the coastal beaches.
Continue reading ‘Hydrographical studies in the nearshore seawaters of the Red Sea coast of Al-Hodeida city, Yemen’Implications of ocean acidification on micronutrient elements-iron, copper and zinc, and their primary biological impacts: a review
Published 30 January 2024 Science ClosedTags: chemistry, review
This review has been undertaken to understand the effectiveness of ocean acidification on oceanic micronutrient metal cycles (iron, copper and zinc) and its potential impacts on marine biota. Ocean acidification will slow down the oxidation of Fe(II) thereby retarding Fe(III) formation and subsequent hydrolysis/precipitation leading to an increase in iron bioavailability. Further, the increased primary production sustains enzymatic bacteria assisted Fe(III) reduction and subsequently the binding of weaker ligands favours the dissociation of free Fe(II) ions, thus increasing the bioavailability. The increasing pCO2 condition increases the bioavailability of copper ions by decreasing the availability of free CO32− ligand concentration. The strong complexation by dissolved organic matter may decrease the bioavailable iron and zinc ion concentration. Since ocean acidification affects the bioavailability of essential metals, studies on the uptake rates of these elements by phytoplankton should be carried out to reveal the future scenario and its effect on natural environment.
Transcriptomics, proteomics, and physiological assays reveal immunosuppression in the eastern oyster Crassostrea virginica exposed to acidification stress
Published 30 January 2024 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, mortality, multiple factors, North Atlantic, pathogens, performance, physiology
Ocean acidification (OA) is recognized as a major stressor for a broad range of marine organisms, particularly shell-building invertebrates. OA can cause alterations in various physiological processes such as growth and metabolism, although its effect on host-pathogen interactions remains largely unexplored. In this study, we used transcriptomics, proteomics, and physiological assays to evaluate changes in immunity of the eastern oyster Crassostrea virginica exposed to OA conditions (pH = 7.5 vs pH = 7.9) at various life stages. The susceptibility of oyster larvae to Vibrio infection increased significantly (131 % increase in mortality) under OA conditions, and was associated with significant changes in their transcriptomes. The significantly higher mortality of larvae exposed to pathogens and acidification stress could be the outcome of an increased metabolic demand to cope with acidification stress (as seen by upregulation of metabolic genes) at the cost of immune function (downregulation of immune genes). While larvae were particularly vulnerable, juveniles appeared more robust to the stressors and there were no differences in mortality after pathogen (Aliiroseovarius crassostrea and Vibrio spp.) exposure. Proteomic investigations in adult oysters revealed that acidification stress resulted in a significant downregulation of mucosal immune proteins including those involved in pathogen recognition and microbe neutralization, suggesting weakened mucosal immunity. Hemocyte function in adults was also impaired by high pCO2, with a marked reduction in phagocytosis (67 % decrease in phagocytosis) in OA conditions. Together, results suggest that OA impairs immune function in the eastern oyster making them more susceptible to pathogen-induced mortality outbreaks. Understanding the effect of multiple stressors such as OA and disease is important for accurate predictions of how oysters will respond to future climate regimes.
Continue reading ‘Transcriptomics, proteomics, and physiological assays reveal immunosuppression in the eastern oyster Crassostrea virginica exposed to acidification stress’The interplay of freshwater inputs and catchment geology in regulating seawater chemistry in Irish coastal areas
Published 30 January 2024 Science ClosedTags: chemistry, field, North Atlantic
Highlights
- Coastal carbonate chemistry depends on land-ocean interactions.
- Multiple drivers should be considered: bedrock geology, freshwater inputs typology.
- Human activities and SGD might affect coastal buffering capacity and TA:DIC ratio.
- TA and DIC should be included in all coastal monitoring programs.
Abstract
Open ocean carbonate chemistry is altered by the dissolution of atmospheric CO2 in seawater. Up to 40% of anthropogenic CO2 emissions have dissolved in the surface ocean since the pre-industrial era, driving changes in marine carbonate pools and promoting ocean acidification. Under open ocean conditions, Total Alkalinity (TA) generally relates with salinity and temperature due to the conservative nature of its constituents. In coastal areas, however, land-ocean interactions may greatly contribute to making TA far less predictable, since freshwater inputs can affect the chemistry of coastal water masses by increasing TA and Dissolved Inorganic Carbon (DIC) or, alternatively, lowering them through dilution. Here we analysed and compared coastal carbonate chemistry dynamics in selected coastal areas of Ireland, in order to assess whether rivers and their catchment geology can influence coastal water chemistry and to verify the occurrence of local ocean acidification processes. Data on TA, DIC, salinity, temperature, and nutrients (total nitrogen, phosphate, and silicate) collected during several surveys along the Irish coastline by The Marine Institute Foras Na Mara (MIFNM) from 2009 to 2018 were analysed against those available on the main watercourses feeding the selected coastal areas. The relationships among the different variables were scrutinized, also considering the geological characteristics of river catchments. Results showed a clear linkage between coastal water chemistry and local freshwater inputs, whereas changes in the geology of catchment areas exerted only a secondary influence. An in-depth scrutiny of the Galway Bay sector performed by comparing MIFNM data with those collected during an oceanographic cruise carried out in October 2017 further indicated remarkable effects of the interaction between river inputs and submarine groundwater discharges on seasonal variations in the water chemistry of the area. Future studies, integrating chemical data across the land-ocean boundary, may provide additional, useful information on the factors actually affecting the variation in water carbonates in coastal areas. Elucidating how land-ocean interactions influence the coastal carbonate system may ultimately provide a key for a more advanced understanding of the resilience of coastal areas to ocean acidification.
Continue reading ‘The interplay of freshwater inputs and catchment geology in regulating seawater chemistry in Irish coastal areas’Examining the impacts of elevated, variable pCO2 on larval Pacific razor clams (Siliqua patula) in Alaska
Published 29 January 2024 Science ClosedTags: biological response, calcification, laboratory, molecular biology, mollusks, morphology, North Pacific, physiology
An increase in anthropogenic carbon dioxide is driving oceanic chemical shifts resulting in a long-term global decrease in ocean pH, colloquially termed ocean acidification (OA). Previous studies have demonstrated that OA can have negative physiological consequences for calcifying organisms, especially during early life-history stages. However, much of the previous research has focused on static exposure to future OA conditions, rather than variable exposure to elevated pCO2, which is more ecologically relevant for nearshore species. This study examines the effects of OA on embryonic and larval Pacific razor clams (Siliqua patula), a bivalve that produces a concretion during early shell development. Larvae were spawned and cultured over 28 days under three pCO2 treatments: a static high pCO2 of 867 μatm, a variable, diel pCO2 of 357 to 867 μatm, and an ambient pCO2 of 357 μatm. Our results indicate that the calcium carbonate polymorphism of the concretion phase of S. patula was amorphous calcium carbonate which transitioned to vaterite during the advanced D-veliger stage, with a final polymorphic shift to aragonite in adults, suggesting an increased vulnerability to dissolution under OA. However, exposure to elevated pCO2 appeared to accelerate the transition of larval S. patula from the concretion stage of shell development to complete calcification. There was no significant impact of OA exposure to elevated or variable pCO2 conditions on S. patula growth or HSP70 and calmodulin gene expression. This is the first experimental study examining the response of a concretion producing bivalve to future predicted OA conditions and has important implications for experimentation on larval mollusks and bivalve management.
Continue reading ‘Examining the impacts of elevated, variable pCO2 on larval Pacific razor clams (Siliqua patula) in Alaska’The annual update GLODAPv2.2023: the global interior ocean biogeochemical data product
Published 29 January 2024 Science ClosedTags: chemistry, field
The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort providing regular compilations of surface-to-bottom ocean biogeochemical bottle data, with an emphasis on seawater inorganic carbon chemistry and related variables determined through chemical analysis of seawater samples. GLODAPv2.2023 is an update of the previous version, GLODAPv2.2022 (Lauvset et al., 2022). The major changes are as follows: data from 23 new cruises were added. In addition, a number of changes were made to data included in GLODAPv2.2022. GLODAPv2.2023 includes measurements from more than 1.4 million water samples from the global oceans collected on 1108 cruises. The data for the now 13 GLODAP core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, chlorofluorocarbon-11 (CFC-11), CFC-12, CFC-113, CCl4, and SF6) have undergone extensive quality control with a focus on systematic evaluation of bias. The data are available in two formats: (i) as submitted by the data originator but converted to World Ocean Circulation Experiment (WOCE) exchange format and (ii) as a merged data product with adjustments applied to minimize bias. For the present annual update, adjustments for the 23 new cruises were derived by comparing those data with the data from the 1085 quality-controlled cruises in the GLODAPv2.2022 data product using crossover analysis. SF6 data from all cruises were evaluated by comparison with CFC-12 data measured on the same cruises. For nutrients and ocean carbon dioxide (CO2) chemistry comparisons to estimates based on empirical algorithms provided additional context for adjustment decisions. The adjustments that we applied are intended to remove potential biases from errors related to measurement, calibration, and data handling practices without removing known or likely time trends or variations in the variables evaluated. The compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 μmol kg-1 in dissolved inorganic carbon, 4 μmol kg-1 in total alkalinity, 0.01–0.02 in pH (depending on region), and 5 % in the halogenated transient tracers. The other variables included in the compilation, such as isotopic tracers and discrete CO2 fugacity (fCO2), were not subjected to bias comparison or adjustments.
The original data, their documentation and DOI codes are available at the Ocean Carbon and Acidification Data System of NOAA NCEI, which also provides access to the merged data product. This is provided as a single global file and as four regional ones – the Arctic, Atlantic, Indian, and Pacific oceans – under https://doi.org/10.25921/zyrq-ht66 (Lauvset et al., 2023). These bias-adjusted product files also include significant ancillary and approximated data, which were obtained by interpolation of, or calculation from, measured data. This living data update documents the GLODAPv2.2023 methods and provides a broad overview of the secondary quality control procedures and results.
Continue reading ‘The annual update GLODAPv2.2023: the global interior ocean biogeochemical data product’Assessment of warm-water coral reef tipping point thresholds
Published 29 January 2024 Science ClosedTags: biological response, corals, performance, review
Warm-water coral reefs are facing unprecedented Anthropogenic driven threats to their continued existence as biodiverse, functional ecosystems upon which hundreds of millions of people rely. Determining the tipping point thresholds of coral reef ecosystems requires robust assessment of multiple stressors and their interactive effects. We draw upon a literature search and the recent Global Tipping Points Revision initiative to consider warm-water coral reef ecosystem tipping point threshold sensitivity. Considering observed and projected stressor impacts we recognise a global mean surface temperature (relative to pre-industrial) tipping point threshold of 1.2 °C (range 0.7–1.5 °C) and an atmospheric CO2 warming threshold of 350 ppm (range 326–400 ppm), whilst acknowledging that interacting stressors, ocean warming response time, overshoot and cascading impacts have yet to be sufficiently assessed but are likely to lower this threshold. These uncertainties around tipping point sensitivities for such a crucially important ecosystem underlines the imperative of robust assessment and, in the case of knowledge gaps, employing a precautionary principle favouring the lower range tipping point values.
Continue reading ‘Assessment of warm-water coral reef tipping point thresholds’Uncertainty sources for measurable ocean carbonate chemistry variables
Published 29 January 2024 Science ClosedTags: chemistry, review
The ocean carbonate system is critical to monitor because it plays a major role in regulating Earth’s climate and marine ecosystems. It is monitored using a variety of measurements, and it is commonly understood that all components of seawater carbonate chemistry can be calculated when at least two carbonate system variables are measured. However, several recent studies have highlighted systematic discrepancies between calculated and directly measured carbonate chemistry variables and these discrepancies have large implications for efforts to measure and quantify the changing ocean carbon cycle. Given this, the Ocean Carbonate System Intercomparison Forum (OCSIF) was formed as a working group through the Ocean Carbon and Biogeochemistry program to coordinate and recommend research to quantify and/or reduce uncertainties and disagreements in measurable seawater carbonate system measurements and calculations, identify unknown or overlooked sources of these uncertainties, and provide recommendations for making progress on community efforts despite these uncertainties. With this paper we aim to (1) summarize recent progress toward quantifying and reducing carbonate system uncertainties; (2) advocate for research to further reduce and better quantify carbonate system measurement uncertainties; (3) present a small amount of new data, metadata, and analysis related to uncertainties in carbonate system measurements; and (4) restate and explain the rationales behind several OCSIF recommendations. We focus on open ocean carbonate chemistry, and caution that the considerations we discuss become further complicated in coastal, estuarine, and sedimentary environments.
Continue reading ‘Uncertainty sources for measurable ocean carbonate chemistry variables’
