One of the main issues emerging from environmental change with significant ramifications for marine life is Ocean acidification. It alludes to the cycle by which the sea turns out to be more acidic because of expansion in the concentration of carbon dioxide in the environment. As carbon dioxide levels ascend in climate a critical part is consumed by the sea which prompts a progression of redox responses that decline the pH of ocean water. This peculiarity has broad ramifications for marine life, especially for coral reefs, which are among the most miscellaneous and monetarily significant biological ecosystems in the world. The purpose of this review is to address and assess the impact of ocean acidification on coral reefs and marine life in order to conserve and sustain marine life below water thus fulfilling Sustainable Development Goal 14 (Life below water).
Continue reading ‘Addressing the impact of ocean acidification on coral reefs and marine life: a risk assessment for SDG 14 (life below water)’Archive Page 57
Addressing the impact of ocean acidification on coral reefs and marine life: a risk assessment for SDG 14 (life below water)
Published 10 December 2024 Science ClosedTags: biological response, corals, Indian, mitigation, review
Ocean acidification and plankton
Published 10 December 2024 Science ClosedTags: biological response, community composition, otherprocess, performance, physiology, phytoplankton, review
Ocean acidification represents a significant and growing threat to some species of marine plankton, with wide-ranging implications for marine ecosystems and the services they provide. The alterations in plankton physiology, behavior, and community structure under acidified conditions exemplify the profound impact of anthropogenic CO₂ emissions on the ocean’s smallest, yet most essential inhabitants.
Continue reading ‘Ocean acidification and plankton’Marine water acidification and coral bleaching
Published 10 December 2024 Science ClosedTags: biological response, BRcommunity, corals, mitigation, protists, review
Coral reefs are vital marine ecosystems that harbor a significant proportion of the ocean’s biodiversity. However, these ecosystems are increasingly threatened by anthropogenic activities, particularly the emission of greenhouse gases leading to climate change and ocean acidification. Ocean acidification refers to the reduction in pH of marine waters due to the absorption of CO₂ from the atmosphere, forming carbonic acid (H₂CO₃), which dissociates into bicarbonate (HCO₃−) and hydrogen ions (H+), thus lowering pH. This sequence of reactions leads to an increase in hydrogen ion concentration, causing a decrease in pH. The reduction in carbonate ions (CO₃2−) is particularly detrimental to marine calcifiers, including corals, which rely on carbonate for the formation of their calcium carbonate (CaCO₃) skeletons. Coral reefs are constructed by the deposition of CaCO₃ by coral polyps. Zooxanthellae, symbiotic algae living within coral tissues, provide essential nutrients through photosynthesis, facilitating calcification. Acidification disrupts this symbiotic relationship by impairing photosynthetic efficiency and reducing the availability of carbonate ions necessary for skeletal growth. As ocean acidification progresses, the concentration of carbonate ions diminishes, making it energetically more challenging for corals to secrete their skeletons, thereby slowing growth rates and compromising structural integrity. Coral bleaching occurs when corals, under stress, expel their zooxanthellae, leading to a loss of pigmentation and a decline in energy reserves. Stressors include elevated sea temperatures, pollution, and acidification. The loss of zooxanthellae not only deprives corals of their primary food source but also disrupts calcification processes. Thermal stress is a predominant factor in coral bleaching. Elevated sea temperatures can destabilize the photosynthetic machinery of zooxanthellae, producing reactive oxygen species (ROS) that damage both the algae and coral tissues. Prolonged exposure to high temperatures exacerbates acidification effects, intensifying bleaching events. The decline in coral health due to bleaching and acidification has profound ecological impacts, including the loss of habitat for numerous marine species, reduced biodiversity, and compromised fisheries. Socioeconomically, coral reef degradation affects tourism, coastal protection, and the livelihoods of communities dependent on reef resources. Reduction of CO₂ emissions through global policy agreements and renewable energy adoption. Local conservation efforts, such as marine protected areas (MPAs) have the potentials to enhance reef resilience. Conservation efforts may be complemented by research into coral species and strains with higher tolerance to acidification and thermal stress, potentially involving selective breeding and genetic modification. Marine water acidification and coral bleaching are intricately linked phenomena driven by anthropogenic climate change. The decline of coral reefs signals a broader environmental crisis that necessitates urgent scientific, policy, and community responses to mitigate adverse effects and foster adaptive resilience in marine ecosystems.
Continue reading ‘Marine water acidification and coral bleaching’Synergistic effects of ocean acidification and sulfamethoxazole on immune function, energy allocation, and oxidative stress in Trochus niloticus
Published 9 December 2024 Science ClosedTags: biological response, mollusks, multiple factors, physiology, respiration, toxicants
Highlights
- Dual stress of OA and SMX may harm survival and reproduction in T. niloticus.
- OA increased immune and antioxidant responses in T. niloticus.
- SMX exposure boosted antioxidant responses and oxygen consumption.
- Exposure to OA combined with SMX impaired cellular energy allocation in T. niloticus.
Abstract
Ocean acidification, a major consequence of climate change, poses significant threats to marine organisms, particularly when combined with other environmental stressors such as chemical pollution. This study investigated the physiological responses of Trochus niloticus to a 28-day exposure of ocean acidification and/or sulfamethoxazole, a commonly detected antibiotic in the South China Sea. Exposure to either acidification or sulfamethoxazole individually triggered adaptive responses through immune activation, antioxidant reactions, and metabolic adjustments. However, concurrent exposure resulted in significant adverse effects, including compromised immunity, oxidative damage, and disrupted energy budget. These findings provide new insights into how ocean acidification interacts with antibiotic pollution to synergistically impact marine gastropods, suggesting that multiple stressors may pose greater threats to T. niloticus populations than single stressors alone.
Continue reading ‘Synergistic effects of ocean acidification and sulfamethoxazole on immune function, energy allocation, and oxidative stress in Trochus niloticus’The important role of the antioxidant stress capacity in the response of Prochlorococcus to increased CO2 under varying iron and light conditions
Published 9 December 2024 Science ClosedTags: biological response, growth, light, multiple factors, nutrients, physiology, prokaryotes
Highlights
- Low-light-adapted Prochlorococcus ecotypes have stronger low-iron adaptation capacity
- Fe limitation in Prochlorococcus is enhanced under both low growth-limiting light and high photo-inhibitory light
- High CO2 promotes the growth of low-light-adapted Prochlorococcus ecotypes due to a reduction in cellular oxidation stress
Abstract
Ocean acidification caused by the ongoing increase in atmospheric carbon dioxide (CO2) is expected to impact the growth of marine phytoplankton. Additionally, CO2-driven climate change influences light intensity and iron (Fe) availability in surface seawaters, two critical factors for marine phytoplankton carbon fixation and growth due to their central role in regulating photosynthesis. The cyanobacterium Prochlorococcus often dominates marine productivity in oligotrophic oceans with low but variable Fe concentrations and light intensities. However, the combined effects of light intensity, Fe availability and CO2 concentration on the growth and photosynthesis of Prochlorococcus remain unclear. In this study, we found that the high-light-adapted Prochlorococcus strain MED4, isolated from shallower depths, required much higher Fe concentrations and light intensities to grow than the low-light-adapted strain NATL1A, isolated from deeper depths. Increased CO2 had no effect on the growth of strain MED4 under any light or Fe conditions. In contrast, increased CO2 caused a 29% increase in the growth of strain NATL1A under low Fe coupled with high photo-inhibitory light condition, owing to a reduction in cellular oxidative stress. The varying antioxidant stress capacities of different Prochlorococcus strains appeared to influence their responses to increased CO2. These results indicate complex interactions among light intensity, Fe limitation, and CO2 concentration, which may affect the species distributions and productivities of marine phytoplankton, including Prochlorococcus, in a future high-CO2 ocean.
Continue reading ‘The important role of the antioxidant stress capacity in the response of Prochlorococcus to increased CO2 under varying iron and light conditions’Hindcast (back to 1955) and forecast (up to 2100) of sea-surface pH at BATS and Hydrostation S (Bermuda area)
Published 9 December 2024 Science ClosedTags: chemistry, modeling, North Atlantic, regionalmodeling
Time-series measurements in the North Atlantic Ocean at the Hydrostation S site (32°10′N, 64°30′W), started in 1954. At that time, it was not yet possible to measure all the properties of the oceanic carbon cycle. However temperature and salinity were measured. We use these important hydrographic data with the knowledge acquired from more recent measurements (since 1989) of the CO2/carbonate properties at the near-by Bermuda Atlantic Time Series Study (BATS; 31°40′N, 64°10′W), to reconstruct, using two different approaches based upon multi-linear-regressions, the pH at this hydrostation S since its beginning. The results provide good estimates of the ocean acidification in the ocean surface of the area of stations S and BATS since the mid 1950’s, an unprecedented near 70-year trend of ocean acidification, as well as a simple way to forecast to 2100 its variations according to the various scenarios of atmospheric CO2 fugacity increase. The simplest approach shown here, further provides an easy way to estimate surface ocean acidification from satellite sea surface temperature measurements.
Continue reading ‘Hindcast (back to 1955) and forecast (up to 2100) of sea-surface pH at BATS and Hydrostation S (Bermuda area)’eCoral: how electrolysis could restore seawater conditions ideal for coral reefs
Published 9 December 2024 Science ClosedTags: chemistry, mitigation
Coral reefs suffer from climate change, including long-term ocean acidification (OA) and warming and short-term bleaching, tropical storms, and pollution events, all of which are increasing in frequency and severity. It is urgent yet unclear how to intervene to save coral reefs. Reversal of the ocean pH to preindustrial levels could restore coral reefs to their preindustrial growth rates; however, strategies to reverse OA on environmentally relevant scales have not been established. Anecdotally, electrolysis seems to help coral reefs recover from acidification and short-term events, but few uncontrolled studies support such claims. Here, using two independent continuum simulation approaches (COMSOL and CrunchFlow), we show the effect of electrolysis on seawater chemistry relevant to coral reef survival and growth. We conclude that near the negative electrodes, the cathodes, seawater pH, supersaturation, and carbonate concentration all increase significantly. Electrolysis of seawater, therefore, can be used to restore preindustrial ocean conditions locally to save coral reefs, an approach termed eCoral here. We anticipate these simulation results to be the starting point for controlled experiments to test whether seawater electrolysis promotes coral reef growth and restoration, as these simulations predict.
Continue reading ‘eCoral: how electrolysis could restore seawater conditions ideal for coral reefs’Comparative physiological and transcriptome analyses reveal the responses to ocean acidification challenge of Mactra veneriformis with different shell colors
Published 6 December 2024 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, physiology, respiration
Mactra veneriformis is highly susceptible to ocean acidification (OA) due to its low shell hardness during its rapid growth period. In this study, oxygen consumption rate, ammonia excretion rate, and transcriptome sequencing of mantle tissue analyses were conducted in white and purple shell-color populations of M. veneriformis under OA stress (pH = 7.6). The findings indicated a significant rise in oxygen consumption rates and ammonia excretion rates following acidification in both the two shell colors, while the clams with purple color showed comparatively lower basal metabolic levels. Transcriptomic analyses demonstrated the expression of key genes related to fatty acid synthesis were significantly inhibited, whereas genes involved in calcification, osmoregulation, and immune response were upregulated under OA exposure in the two shell-color groups. However, some genes such as CA and HSP showed a population-specific response between the two shell-color populations. KEGG enrichment analysis revealed that the MAPK signaling pathway and protein processing in the endoplasmic reticulum were significantly enriched in the two acidification groups. This study provides valuable insights into the response of M. veneriformis to OA stress and also helps to predict the future breeding of valuable strains of M. veneriformis.
Continue reading ‘Comparative physiological and transcriptome analyses reveal the responses to ocean acidification challenge of Mactra veneriformis with different shell colors’Extreme environmental variability induces frontloading of coral biomineralisation genes to maintain calcification under pCO2 variability
Published 6 December 2024 Science ClosedTags: adaptation, biological response, calcification, corals, field, laboratory, mesocosms, molecular biology, otherprocess, photosynthesis, physiology, South Pacific
Corals residing in habitats that experience high-frequency seawater pCO2 variability may possess an enhanced capacity to cope with ocean acidification, yet we lack a clear understanding of the molecular toolkit enabling acclimatisation to environmental extremes or how life-long exposure to pCO2 variability influences biomineralisation. Here, we examined the gene expression responses and micro-skeletal characteristics of Pocillopora damicornis originating from the reef flat and reef slope of Heron Island, southern Great Barrier Reef. The reef flat and reef slope had similar mean seawater pCO2, but the reef flat experienced twice the mean daily pCO2 amplitude (range of 797 v. 399 μatm day−1, respectively). A controlled mesocosm experiment was conducted over 8 weeks, exposing P. damicornis from the reef slope and reef flat to stable (218 ± 9) or variable (911 ± 31) diel pCO2 fluctuations (μatm; mean ± SE). At the end of the exposure, P. damicornis originating from the reef flat demonstrated frontloading of 25% of the expressed genes regardless of treatment conditions, suggesting constitutive upregulation. This included higher expression of critical biomineralisation-related genes such as carbonic anhydrases, skeletal organic matrix proteins, and bicarbonate transporters. The observed frontloading corresponded with a 40% increase of the fastest deposited areas of the skeleton in reef flat corals grown under non-native, stable pCO2 conditions compared to reef slope conspecifics, suggesting a compensatory response that stems from acclimatisation to environmental extremes and/or relief from stressful pCO2 fluctuations. Under escalating ocean warming and acidification, corals acclimated to environmental variability warrant focused investigation and represent ideal candidates for active interventions to build reef resilience while societies adopt strict policies to limit climate change.
Continue reading ‘Extreme environmental variability induces frontloading of coral biomineralisation genes to maintain calcification under pCO2 variability’Major threats to rhodolith beds: ocean acidification, global warming, and local stressors
Published 6 December 2024 Science ClosedTags: algae, biological response, BRcommunity, physiology, review, South Atlantic
Since the industrial revolution, the human population has accelerated its magnitude of impact on the world’s oceans. The observed consequences of our rising population and globalization have expanded substantially and are expected to affect even the deepest ecosystems. The extensive rhodolith beds along the Brazilian coastline that are present from the shallows down to 133 m are predicted and already observed to suffer from the consequences of human interference. Rhodolith beds are predicted to experience a daunting diversity of anthropogenic threats, which act at different scales. Global stressors such as ocean acidification and global climate change are shown to affect fundamental metabolic processes, which over time are expected to jeopardize the integrity of these ecosystems. Local stressors such as nutrient runoff, pollution, oil/gas exploitation, predatory fishing as bottom trawling, and direct coralline mining are expected to interact with global stressors and, in multiple cases, exacerbate already negative prognosis.
Continue reading ‘Major threats to rhodolith beds: ocean acidification, global warming, and local stressors’An updated version of the OA-ICC bibliographic database is available online.
The database currently contains 9131 references and includes citations, abstracts and assigned keywords. Updates are made every month.
The database is available as a group on Zotero. Subscribe online or, for a better user experience, download the Zotero desktop application and sync with the group OA-ICC in Zotero. Please see the “User instructions” for further details.
Continue reading ‘OA-ICC bibliographic database updated’Marine scientific research in the protection of the marine environment under the international legal framework: a sustainable development goals perspective
Published 5 December 2024 Science ClosedTags: policy
Marine Scientific Research (MSR) under Sustainable Development Goal—14 (SDG 14) has envisioned a new dimension of cooperation for marine environmental protection. This chapter has taken the approach of MSR as provided in SDG 14 to provide a cooperative approach for MSR to protect the marine environment. This chapter analyzes the international law provisions dealing with MSR envisioning cooperation for the protection of the marine environment. The chapter has taken three perspectives of the marine environment: (i) climate change, (ii) fisheries preservation, and (iii) marine protected areas, along with scientific approaches required for marine pollution prevention. The conclusion of this chapter follows the challenges and opportunities for MSR cooperation, which could be a future course of research on the subject matter.
Continue reading ‘Marine scientific research in the protection of the marine environment under the international legal framework: a sustainable development goals perspective’Climate resilience and profitability thresholds in chesapeake bay oyster aquaculture
Published 5 December 2024 Science ClosedTags: fisheries, mitigation, mollusks, North Atlantic, socio-economy
Highlights
- Climate change brings offsetting factors for oyster aquaculture.
- By 2068 we project slight profit declines for most locations.
- Optimized profits were driven more by site-to-site differences than future changes.
- Industry growth will be supported by making high quality areas available for leasing.
- Targeted mitigation strategies can boost profits even at high costs.
Abstract
Shellfish aquaculture producers in coastal systems are facing uncertain future growing conditions as climate change alters weather patterns and raises sea level. We examined expected mid-century (2059–2068) changes in aquaculture profitability from recent conditions by integrating models of climate change, estuarine hydrodynamics and biogeochemistry, oyster growth, oyster mortality, and economics, using the Chesapeake Bay, USA as a case study. We developed an economic stochastic dynamic programming (SDP) approach that generates optimal grower behavior to maximize profits under uncertainty by dynamically choosing planting density, replanting and mitigation use, in response to changing oyster stock status and water quality conditions. Separate models were developed for bottom culture largely serving the cannery market, and container culture largely serving the half-shell market, to reflect different production costs, market prices, and oyster growth and survival. The coupled hydrodynamic-biogeochemical and oyster ecology models projected high spatial variability in oyster growth and mortality with the most favorable growing conditions in the lower north and upper mid bay, where mortality is lowest, and the upper south bay, where growth is highest. Climate change by late mid-century generated modest water quality changes and virtually no mortality rate changes. Nonetheless, our modeling revealed that even if growers made optimal management choices under uncertainty, the majority of modeled sites would see a decline in profitability under climate change, primarily due to potential reductions in food availability. Bottom culture was more resilient to the future climate at most sites, being less sensitive to small changes in growth than container culture. Information on how aquaculture conditions currently vary in space was more important for profitability than future climate forecasts. Our stochastic dynamic programming approach tailored grower behavior to each site and unfolding annual conditions, including highly targeted and cost-effective mitigation adjustments to boost oyster survival or growth.
Continue reading ‘Climate resilience and profitability thresholds in chesapeake bay oyster aquaculture’Effects of ocean acidification on abalone (Haliotis spp.) reproduction, early development, and growth: a review
Published 5 December 2024 Science ClosedTags: biological response, calcification, mollusks, morphology, mortality, physiology, reproduction, review, socio-economy
Abalone (Haliotis spp.) is a highly valuable and economically relevant marine commodity worldwide, with its production and value showing significant growth over the past two decades. Additionally, abalone hold essential ecological value by serving as a grazer and providing a microhabitat for various benthic organisms. Currently, seawater is experiencing a decrease in pH due to increased carbon dioxide (CO2) levels. It is projected that by 2100, the pH of seawater will decrease by approximately 0.3–0.4 units, with this trend continuing to 0.7–0.8 units by 2300. Abalone is particularly susceptible to ocean acidification due to its limited ability to maintain acid-base balance. Moreover, even if the effects on abalone are not lethal, world production values and ecosystem balance are likely to be impacted. This review examines the economic and ecological significance of abalone, as well as the morphological and physiological effects of ocean acidification on abalone during its early development, juvenile, and adult stages based on previous studies. In summary, the adverse effects of ocean acidification on abalone depend on several aspects, including the species, developmental stage, size, and duration of exposure.
Continue reading ‘Effects of ocean acidification on abalone (Haliotis spp.) reproduction, early development, and growth: a review’The influence of macrophytes on diurnal pH variability in subtropical estuaries: a mesocosm study
Published 4 December 2024 Science ClosedTags: algae, biological response, BRcommunity, chemistry, Indian, laboratory, mesocosms, phanerogams
Highlights
- Macrophytes influence estuary water column pH levels.
- Floating macrophytes decrease pH and submerged macrophytes increase pH.
- Diurnal pH variability is more pronounced in submerged macroalgae.
- Floating macrophytes exhibit lower diurnal variability.
Abstract
Coastal ecosystems are increasingly threatened by anthropogenic impacts, particularly from land-based activities that drive eutrophication. This research investigated eutrophication and the unique challenges facing southern hemisphere coastal ecosystems. We used a mesocosm study to measure the influence of a macroalga (Rhizoclonium riparium) and a floating macrophyte (Pistia stratiotes), on diurnal pH variability. Diurnal pH variability was more pronounced in the presence of macroalgae due to the direct release of metabolic byproducts into the water column during photosynthesis and respiration. In contrast, floating macrophyte treatments had lower diurnal pH variability, as metabolic byproducts are released into the atmosphere through floating foliage. Floating macrophytes influenced overall water column pH levels, resulting in an acidification effect, becoming more pronounced as macrophyte biomass increased. The study highlighted the importance of nutrient management and its association with macrophytes, to preserve the delicate balance of estuaries, and ensure the sustainable functioning of these critical ecosystems. Further in situ research is recommended to validate and expand on the mesocosm findings.
Continue reading ‘The influence of macrophytes on diurnal pH variability in subtropical estuaries: a mesocosm study’Varying effects of climate change on the photosynthesis and calcification of crustose coralline algae: implications for settlement of coral larvae
Published 4 December 2024 Science ClosedTags: algae, biological response, BRcommunity, calcification, corals, laboratory, molecular biology, multiple factors, photosynthesis, physiology, reproduction, temperature
Highlights
- Corals maintain settlement preferences under future climate conditions
- Future climate conditions negatively affect crustose coralline algae physiology
- Physiological responses to future climate conditions varied by algal species
Abstract
Coral recruitment is critical to the maintenance of healthy coral reef ecosystems. Many coral species settle preferentially on certain crustose coralline algae (CCA) (e.g., Hydrolithon boergesenii) over others (e.g., Paragoniolithon solubile). Calcifying organisms like CCA are particularly susceptible to ocean acidification (OA), and settlement behavior of larvae may be compromised as seawater temperatures increase (ocean warming; OW) and pH levels decrease as a result of climate change. Here, we examine the effects of future seawater conditions (OW and OA) on the calcification and photosynthetic efficiency of two CCA species, H. boergesenii and Pa. solubile. We also examine the effects of conditioning CCA in combined OA and OW on the settlement preferences of three coral species, Acropora palmata, A. cervicornis and Porites astreoides. Acropora palmata and Po. astreoides demonstrated a preference for H. boergesenii over Pa. solubile in choice experiments after short-term treatment (7–21 days) and this preference was not affected by future seawater conditions. A. cervicornis did not demonstrate a CCA preference under any treatment. Po. astreoides did not demonstrate a CCA preference in no-choice assays and settlement was unaffected by OW and OA even after the longest exposure (99 days). Both CCA had reduced photosynthetic efficiency after exposure to future seawater conditions. However, net calcification rate was reduced in H. boergesenii but not Pa. solubile after exposure to future seawater conditions. These results demonstrate that while climate change may differentially affect the physiological functioning of various species of CCA, coral settlement preferences are unlikely to be altered.
Continue reading ‘Varying effects of climate change on the photosynthesis and calcification of crustose coralline algae: implications for settlement of coral larvae’
The rise in carbon dioxide (CO2) levels in our world’s atmosphere is fueling an environmental threat to marine life. Ocean acidification is growing in magnitude as it moves into deeper waters.
Jens Müller and Nicolas Grube are environmental physicists in the Institute of Biogeochemistry and Pollutant Dynamics at ETH Zurich. They set out to investigate the consequences of acidification by developing a 3D model of our oceans.
The research, recently published in the journal Science Advances, sheds light on how ocean acidification has intensified since the industrial revolution kicked off.
…
Mapping ocean acidification depths
Müller and Grube carefully designed an experiment to untangle the spread of ocean acidification.
Their focus: How deep down has acidification seeped into our oceans over time? To answer this, they developed an ocean model simulating the effects of rising atmospheric CO2 levels.
The model was based on historical data spanning over two centuries, with CO2 estimates for the years 1800, 1994, 2004, and 2014. This gave the researchers a timeline to monitor how acidification spread through the ocean layers.
Constructing the ocean model
Creating a model of this scale required careful planning. Starting with a standard ocean model that simulates water movement and chemistry, the researchers then added data points on CO2 levels and acidification indicators like proton concentrations, pH levels, and aragonite saturation states.
This comprehensive approach enabled the experts to accurately map acidification trends.
Acidification reaches new ocean depths
Ocean acidification is moving deeper into the ocean, with the average depth impacted by acidification measuring around 1,000 meters by 2014.
In regions influenced by the Atlantic meridional overturning current, acidification reached depths of up to 1,500 meters.
But this spread isn’t uniform; different ocean regions face varying levels of change due to factors like water circulation patterns and temperature.
…
Future implications of deeper acidification
Müller and Grube’s findings emphasize the urgent need to address carbon emissions. As CO2 levels rise, ocean acidification will only get worse.
The deeper it goes, the harder it is to reverse the impacts. The long-term consequences for marine biodiversity and human communities relying on ocean resources are unclear.
Reducing carbon emissions will help slow acidification. Initiatives to shift to renewable energy, enhance energy efficiency, and promote conservation could also contribute.
…
Continue reading ‘Ocean acidification is spreading into deeper waters’Progression of ocean interior acidification over the industrial era
Published 4 December 2024 Science ClosedTags: chemistry, globalmodeling, modeling
Ocean acidification driven by the uptake of anthropogenic CO2 represents a major threat to ocean ecosystems, yet little is known about its progression beneath the surface. Here, we reconstruct the history of ocean interior acidification over the industrial era on the basis of observation-based estimates of the accumulation of anthropogenic carbon. Across the top 100 meters and from 1800 to 2014, the saturation state of aragonite (Ωarag) and pH = −log[H+] decreased by more than 0.6 and 0.1, respectively, with nearly 50% of the progression occurring over the past 20 years. While the magnitude of the Ωarag change decreases uniformly with depth, the magnitude of the [H+] increase exhibits a distinct maximum in the upper thermocline. Since 1800, the saturation horizon (Ωarag = 1) shoaled by more than 200 meters, approaching the euphotic zone in several regions, especially in the Southern Ocean, and exposing many organisms to corrosive conditions.
Continue reading ‘Progression of ocean interior acidification over the industrial era’Physiological and behavioral responses of the Baltic clam Macoma balthica to a laboratory simulated CO2-leakage from a subseabed carbon storage site
Published 3 December 2024 Science ClosedTags: biological response, laboratory, mollusks, morphology, mortality, North Atlantic, performance, physiology
Highlights
- Baltic clams were exposed to CO2 leakage simulated in laboratory conditions.
- Physiological and behavioral responses of the model organism were evaluated.
- Shell growth in thickness and length were inhibited at pH 6.3.
- Biochemical composition, condition index and burrowing depth results were inconclusive.
Abstract
Carbon capture and storage in sub-seabed geological reservoirs is now officially included in the atmospheric CO2 emissions reduction policy and meets the agenda of Sustainable Development Goals (SDGs). Over the last few years biological risk assessment studies have delivered substantial empirical data on possible consequences of CO2 leakages from underwater storage sites on benthic systems. Current knowledge on Carbon Capture and Storage CCS associated risks is limited to marine systems. Yet there are multiple areas identified as suitable for carbon storage, but their hydrogeochemical features are so distinct that they should be studied as separate cases. Baltic Sea is one example of an area but is host to a unique – in a world scale – ecosystem with low salinity in combination with reduced oxygen availability in the benthic zone. Geological surveys have designated a potential storage site in the Southern Baltic Sea, namely the B3 oil field. Thus, this study focuses on biological effects of seawater acidification caused by a simulated CO2 leakage scenarios under laboratory conditions on a model macrobenthic in-faunal species. Baltic clams Macoma balthica were exposed to different environmental pH scenarios: pH 7.7 (no leakage), pH 7.0 (moderate hypercapnia) and pH 6.3 (severe hypercapnia) in three independent experiments conducted with the use of a hyperbaric tank (Karl Eric Titank) mimicking hydrostatic pressure of 900 kPa, relevant to conditions at the B3 field. Selected physiological aspects of the Baltic clam, such as survival, shell growth rate, morphometric condition and biochemical composition were investigated along with their behavioral responses, i.e. sediment burrowing activity. The results showed modest effects of hypercapnia on physiological performance of the clams that did not lead to greater mortality in neither of the tested leakage scenarios. Apart from high survival of the clams even in the lowest seawater pH (6.3) there were only little changes observed in the burrowing depth of the clams and biochemical composition of their soft tissues related to seawater acidification. The most evident physiological responses of the clams to prolonged hypercapnia (40 days at pH 6.3) were manifested in decreased shell growth.
Sea-air CO2 exchanges, pCO2 drivers and phytoplankton communities in the southwestern South Atlantic Ocean during spring
Published 3 December 2024 Science ClosedTags: biological response, chemistry, community composition, field, otherprocess, phytoplankton, respiration, South Atlantic
Highlights
- The southwestern Brazilian margin behaved as a weak CO2 outgassing zone in austral spring of 2014.
- Haptophytes were conspicuous along the entire study area, while Trichodesmium was prominent at SBB and diatoms at SBS.
- CaCO3 production was observed at SBB, whereas seawater dilution dominated the changes of sea surface pCO2 at SBS.
- Nitrification by Trichodesmium likely allowed increased contribution of haptophytes seen at open ocean oligotrophic waters.
- Net respiration was the main biogeochemical process regulating sea-air CO2 exchanges in the study area.
Abstract
Hydrographic properties and carbon dioxide partial pressure (pCO2) were measured through underway survey of surface waters during spring 2014, mainly along the Surface Haline Front in the continental shelf-break domain in the southwestern South Atlantic Ocean margin. Additionally, discrete seawater surface samples were collected along the ship track to identify the phytoplankton community and measure seawater chemical properties. This study aims to identify the drivers of the marine CO2‑carbonate chemistry and the role played by the phytoplankton composition on changes in the surface marine carbonate properties and the sea-air CO2 exchanges in two biogeochemical provinces (i.e., South Brazil Bight – SBB, and Southern Brazilian Shelf – SBS) governed by the dynamics of the Brazil Current system in the South Atlantic Ocean. The water masses identified on the surface of the region were Tropical Water (mostly present at offshore regions), Subtropical Shelf Water (mostly present over the continental shelf and slope), and Plata Plume Water (present in the south coastal domain of the SBS). On average, the study area behaved as a weak net CO2 outgassing zone of 1.2 ± 2.3 mmol m−2 d−1 during the spring, despite some subregions behaving as CO2 ingassing zones. The CO2 uptake verified in the SBB was related with mesoscale activity bringing cold waters in the region while CO2 uptake in the continental shelf domain of SBS was associated with the presence of cooler and fresher Plata Plume Water. Changes in total alkalinity and dissolved inorganic carbon at surface were mainly governed by CaCO3 production in SBB and seawater dilution in SBS, although other processes may also have influenced on their spatial variability. The dominant phytoplankton groups were haptophytes (31 %), Trichodesmium (21 %), and picocyanobateria (28 %), corresponding to Synechococcus (17 %) and Prochlorococcus (11 %). The dominance of the diatom group was associated with a decrease in sea surface pCO2 (mainly at coastal zones at southern areas), although the sea-air CO2 exchanges were regulated by cooling process due the presence of Plata Plume Water in that region. Changes in surface pH were related to high concentration of Trichodesmium slicks at offshore zones with the highest microalgae concentration, leading to pH drops of up to 0.4. Trichodesmium slicks likely allowed the development of haptophytes in offshore oligotrophic waters due to its role on N2 fixation. An increase of ∼20 % in the dominance of haptophytes contribution was verified in that situation, which was likely in a post-bloom development stage, since an increased dissolved inorganic carbon content was observed, associated with a prevalence of net respiration processes.
Continue reading ‘Sea-air CO2 exchanges, pCO2 drivers and phytoplankton communities in the southwestern South Atlantic Ocean during spring’
