Marine organisms are simultaneously exposed to anthropogenic stressors associated with ocean acidification and ocean warming, with expected interactive effects. Species from different trophic levels with dissimilar characteristics and evolutionary histories are likely to respond differently. Here, we perform a meta-analysis of controlled experiments including both ocean acidification and ocean warming factors to investigate single and interactive effects of these stressors on marine species. Contrary to expectations, we find that synergistic interactions are less common (16%) than additive (40%) and antagonistic (44%) interactions overall and their proportion decreases with increasing trophic level. Predators are the most tolerant trophic level to both individual and combined effects. For interactive effects, calcifying and non-calcifying species show similar patterns. We also identify climate region-specific patterns, with interactive effects ranging from synergistic in temperate regions to compensatory in subtropical regions, to positive in tropical regions. Our findings improve understanding of how ocean warming, and acidification affect marine trophic levels and highlight the need for deeper consideration of multiple stressors in conservation efforts.
Continue reading ‘Responses of marine trophic levels to the combined effects of ocean acidification and warming’Posts Tagged 'review'
Responses of marine trophic levels to the combined effects of ocean acidification and warming
Published 25 April 2024 Science Leave a CommentTags: review
Climate change effects on aquaculture production and its sustainable management through climate-resilient adaptation strategies: a review
Published 24 April 2024 Science Leave a CommentTags: fisheries, policy, review, socio-economy
Aquaculture witnessed a remarkable growth as one of the fastest-expanding sector in the food production industry; however, it faces serious threat from the unavoidable impacts of climate change. Understanding this threat, the present review explores the consequences of climate change on aquaculture production and provides need based strategies for its sustainable management, with a particular emphasis on climate-resilient approaches. The study examines the multi-dimensional impacts of climate change on aquaculture which includes the shifts in water temperature, sea-level rise, ocean acidification, harmful algal blooms, extreme weather events, and alterations in ecological dynamics. The review subsequently investigates innovative scientific interventions and climate-resilient aquaculture strategies aimed at strengthening the adaptive capacity of aquaculture practices. Some widely established solutions include selective breeding, species diversification, incorporation of ecosystem-based management practices, and the implementation of sustainable and advanced aquaculture systems (aquaponics and recirculating aquaculture systems (RAS). These strategies work towards fortifying aquaculture systems against climate-induced disturbances, thereby mitigating risks and ensuring sustained production. This review provides a detailed insight to the ongoing discourse on climate-resilient aquaculture, emphasizing an immediate need for prudent measures to secure the future sustainability of fish food production sector.
Continue reading ‘Climate change effects on aquaculture production and its sustainable management through climate-resilient adaptation strategies: a review’Impact of anthropogenic global hypoxia on the physiological response of bivalves
Published 15 April 2024 Science Leave a CommentTags: biological response, chemistry, mollusks, physiology, review
Dissolved oxygen (DO) is an important parameter that affects the biology, physiology, and immunology of aquatic animals. In recent decades, DO levels in the global oceans have sharply decreased, partly due to an increase in atmospheric carbon dioxide, temperature, and anthropogenic nutrient loads. Although there have been many reports on the effects of hypoxia on the survival, growth, behavior, and immunity of bivalves, this information has not been well organized. Therefore, this article provides a comprehensive review of the effects of hypoxia on bivalves. In general, hypoxia negatively impacts the food consumption rate and assimilation efficiency, as well as increasing respiration rates in many bivalves. As a result, it reduces the energy allocation for bivalve growth, shell formation, and reproduction. In severe cases, prolonged exposure to hypoxia can result in mass mortality in bivalves. Moreover, hypoxia also has adverse effects on the immunity and response of bivalves to predators, including decreased burial depths, sensitivity to predators, impairment of byssus production, and negatively impacts on the integrity, strength, and composition of bivalve shells. The tolerance of bivalves to hypoxia largely depends on size and species, with larger bivalves being more susceptible to hypoxia and intertidal species being relatively more tolerant to hypoxia. The information in this article is very useful for elucidating the current research status of hypoxia on bivalves and determining future research directions.
Continue reading ‘Impact of anthropogenic global hypoxia on the physiological response of bivalves’Comprehensive assessment of copper’s effect on marine organisms under ocean acidification and warming in the 21st century
Published 15 April 2024 Science Leave a CommentTags: biological response, methods, review
Highlights
- The MLR models between pH, temperature and Cu toxicity were developed.
- The WQC of Cu for 2020, 2099-RCP2.6, 2099-RCP4.5, and 2099-RCP8.5 were derived.
- Cu in the Ocean of East China poses a moderate ecological risk.
- Ocean acidification and warming can increase the effects of Cu on marine organisms.
- Cu’s ecological risk in 2099 under RCP2.6 is significantly lower than that of RCP8.5.
Abstract
Copper (Cu) has sparked widespread global concern as one of the most hazardous metals to aquatic animals. Ocean acidification (OA) and warming (OW) are expected to alter copper’s bioavailability based on pH and temperature-sensitive effects; research on their effects on copper on marine organisms is still in its infancy. Therefore, under representative concentration pathways (RCP) 2.6, 4.5, and 8.5, we used the multiple linear regression-water quality criteria (MLR-WQC) method to assess the effects of OA and OW on the ecological risk posed by copper in the Ocean of East China (OEC), which includes the Bohai Sea, Yellow Sea, and East China Sea. The results showed that there was a positive correlation between temperature and copper toxicity, while there was a negative correlation between pH and copper toxicity. The short-term water quality criteria (WQC) values were 1.53, 1.41, 1.30 and 1.13 μg·L−1, while the long-term WQC values were 0.58, 0.48, 0.40 and 0.29 μg·L−1 for 2020, 2099-RCP2.6, 2099-RCP4.5 and 2099-RCP8.5, respectively. Cu in the OEC poses a moderate ecological risk. Under the current copper exposure situation, strict intervention (RCP2.6) only increases the ecological risk of copper exposure by 20 %, and no intervention (RCP8.5) will increase the ecological risk of copper exposure by nearly double. The results indicate that intervention on carbon emissions can slow down the rate at which OA and OW worsen the damage copper poses to marine creatures. This study can provide valuable information for a comprehensive understanding of the combined impacts of climate change and copper on marine organisms.
Continue reading ‘Comprehensive assessment of copper’s effect on marine organisms under ocean acidification and warming in the 21st century’Hidden impacts of ocean warming and acidification on biological responses of marine animals revealed through meta-analysis
Published 12 April 2024 Science ClosedTags: methods, review
Conflicting results remain on the impacts of climate change on marine organisms, hindering our capacity to predict the future state of marine ecosystems. To account for species-specific responses and for the ambiguous relation of most metrics to fitness, we develop a meta-analytical approach based on the deviation of responses from reference values (absolute change) to complement meta-analyses of directional (relative) changes in responses. Using this approach, we evaluate responses of fish and invertebrates to warming and acidification. We find that climate drivers induce directional changes in calcification, survival, and metabolism, and significant deviations in twice as many biological responses, including physiology, reproduction, behavior, and development. Widespread deviations of responses are detected even under moderate intensity levels of warming and acidification, while directional changes are mostly limited to more severe intensity levels. Because such deviations may result in ecological shifts impacting ecosystem structures and processes, our results suggest that climate change will likely have stronger impacts than those previously predicted based on directional changes alone.
Continue reading ‘Hidden impacts of ocean warming and acidification on biological responses of marine animals revealed through meta-analysis’Will climate change and ocean acidification lead to the massive death of marine organisms?
Published 12 April 2024 Science ClosedTags: review
Ocean acidification represents a threat to marine species worldwide, and forecasting the ecological impacts of acidification is a high priority for science, management, and policy. As research on the topic expands at an exponential rate, a comprehensive understanding of the variability in organisms’ responses and corresponding levels of certainty is necessary to forecast the ecological effects. More specifically, what stands to be understood from this review is an understanding of the effects of ocean acidification and whether marine organisms have sufficient physiological plasticity to adapt to the changes in their environment as pCO2 concentration continues to rise. An experiment assessing the impact of ocean acidification on a given species, community, or ecosystem should include realistic changes for all environmental drivers (CO2, temperature, salinity, food concentrations, light availability), and be long-term (i.e., several years) to allow for natural variability and multiple generations of each species under consideration. Single experimental approaches on single organisms often do not capture the true level of complexity of in situ marine environments, and multi-disciplinary approaches involving technological advancements and development are critically needed before a correct determination is made on the mortality of marine organisms.
Continue reading ‘Will climate change and ocean acidification lead to the massive death of marine organisms?’Disparate response of decapods to low pH: a meta-analysis of life history, physiology and behavior traits across life stages and environments
Published 5 April 2024 Science ClosedTags: biological response, calcification, crustaceans, growth, mortality, performance, physiology, reproduction, review
Highlights
- Predicted level of ocean acidification is a threat for calcifier marine invertebrates.
- Decapods, thought debatable, are presumably resilient.
- Our meta-analysis revealed few impacts that mainly vary across biological traits.
- Effect sizes little vary depending on the life stages and environments.
Abstract
We employed a meta-analysis to determine if the presumed resilience of decapods to ocean acidification extends to all biological aspects, environments, and life stages. Most response categories appeared unaffected by acidification. However, certain fitness-related traits (growth, survival, and, to some extent, calcification) were impacted. Acid-base balance and stress response scaled positively with reductions in pH, which maintains homeostasis, possibly at the cost of other processes. Juveniles were the only stage impacted by acidification, which is believed to reduce recruitment. We observed few differences in responses to acidification among decapods inhabiting contrasting environments. Our meta-analysis shows decapods as a group slightly to moderately sensitive to low pH, with impacts on some biological aspects rather than on all specific life stages or habitats. Although extreme pH scenarios may not occur in the open ocean, coastal and estuarine areas might experience lower pH levels in the near to medium future, posing potential challenges for decapods.
Continue reading ‘Disparate response of decapods to low pH: a meta-analysis of life history, physiology and behavior traits across life stages and environments’The effect of climate change on sources of radionuclides to the marine environment
Published 4 April 2024 Science ClosedTags: review
Climate change interacts with the sources and cycling of contaminants, such as radionuclides, in the environment. In this review, we discuss the implications of climate change impacts on existing and potential future sources of radionuclides associated with human activities to the marine environment. The overall effect on operational releases of radionuclides from the nuclear and non-nuclear sectors will likely be increased interference or prevention of normal operations due to weather-related events. For certain radioactive waste dumped at sea and sunken nuclear submarines, the impact of climate change and ocean acidification on the release of radionuclides and their subsequent fate in the marine environment should be considered further. Fluxes from secondary sources of radionuclides in the marine and terrestrial environment and cryosphere will change in response to climate change impacts such as sea level rise, warming and changes in precipitation patterns. In addition, climate change impacts may increase the risk of releases of radionuclides from operational and legacy wastes on land to the marine environment. Overall, our synthesis highlights that there is a need to understand and assess climate change impacts on sources of radionuclides to the marine environment to meet environmental and management challenges under future climate scenarios.
Continue reading ‘The effect of climate change on sources of radionuclides to the marine environment’Submarine groundwater discharge and ocean acidification: implications from China’s coastal waters
Published 3 April 2024 Science ClosedTags: chemistry, review
Highlights
- Uncertainties exist in SGD and coastal acidification characterization.
- Relative paucity of studies on SGD input carbon at different scales in China.
- Consider coupling of SGD-carried nutrients and carbon to coastal acidification.
- Consider conducting qualitative and quantitative studies on SGD and acidification.
Abstract
Ocean acidification (OA) is a global environmental concern, and submarine groundwater discharge (SGD) is a potentially process that enhances OA. This review summarizes the relationship between two types of constituents carried by SGD into China’s seawater and OA. 1) Current research predominantly concentrates on constituent fluxes from SGD, neglecting its ecological impacts on carbon and nutrients budgets, as well as the mechanisms between carbon and nutrients. 2) Uncertainties persist in SGD research methods and acidification characterization. 3) There’s a need to enhance quantitative research methods of SGD-OA, particularly in areas with intricate biogeochemical processes. Effective identification methods are crucial to quantify SGD’s contribution to OA. Investigating core scientific questions, including SGD’s impact on OA rates and scales, is paramount. While the primary focus is on SGD-OA research in China, insights gained from novel perspectives could have broader value for coastal management globally.
Continue reading ‘Submarine groundwater discharge and ocean acidification: implications from China’s coastal waters’Systematic review of the uncertainty of coral reef futures under climate change
Published 3 April 2024 Science ClosedTags: corals, review
Climate change impact syntheses, such as those by the Intergovernmental Panel on Climate Change, consistently assert that limiting global warming to 1.5 °C is unlikely to safeguard most of the world’s coral reefs. This prognosis is primarily based on a small subset of available models that apply similar ‘excess heat’ threshold methodologies. Our systematic review of 79 articles projecting coral reef responses to climate change revealed five main methods. ‘Excess heat’ models constituted one third (32%) of all studies but attracted a disproportionate share (68%) of citations in the field. Most methods relied on deterministic cause-and-effect rules rather than probabilistic relationships, impeding the field’s ability to estimate uncertainty. To synthesize the available projections, we aimed to identify models with comparable outputs. However, divergent choices in model outputs and scenarios limited the analysis to a fraction of available studies. We found substantial discrepancies in the projected impacts, indicating that the subset of articles serving as a basis for climate change syntheses may project more severe consequences than other studies and methodologies. Drawing on insights from other fields, we propose methods to incorporate uncertainty into deterministic modeling approaches and propose a multi-model ensemble approach to generating probabilistic projections for coral reef futures.
Continue reading ‘Systematic review of the uncertainty of coral reef futures under climate change’Recent developments in ionophore-based potentiometric electrochemical sensors for oceanic carbonate detection
Published 18 March 2024 Science ClosedTags: chemistry, field, multiple factors, review, salinity, sensor, temperature
The increasing level of atmospheric carbon dioxide (CO2) driven by human activities contributes to the global concern of climate change. A consequence of these circumstances is ocean acidification, which reduces seawater pH. The increasing absorption of atmospheric CO2 into the ocean decreases the concentration of carbonate ions and causes the sea to become more acidic, severely harming marine species. This harm to marine life has created the need for in situ carbonate sensing and monitoring to understand how marine ecosystems respond to pH reduction. Over the past few decades, many sensors with different compositions and structures have been developed to detect carbonate in seawater and other aquatic environments to simulate oceanic conditions. This review summarizes the recent developments in carbonate ionophores, a key component in carbonate electrochemical sensors, and compares the reported performance of these sensors through various parameters (e.g., sensitivity, response time, lifetime, testing media, and measuring range). Current challenges within the development of carbonate ionophores and sensors and possibilities for future research are also discussed.
Continue reading ‘Recent developments in ionophore-based potentiometric electrochemical sensors for oceanic carbonate detection’The rise, fall and rebirth of ocean carbon sequestration as a climate ‘solution’
Published 15 March 2024 Science ClosedTags: mitigation, policy, review
Highlights
- Solutions to the climate crisis are not ahistorical.
- Both social and technical processes explain their rise (or fall) on the agenda.
- Thinking about ocean CDR closely co-evolved with scientific understandings of global climate change.
- Ocean CDR methods have followed cycles of hype, controversy and disappointment.
- Key sociotechnical configurations and narrative changes explain the new hype around ocean CDR.
Abstract
While the ocean has long been portrayed as a victim of climate change, threatened by ocean warming and acidification, it is now increasingly framed as a key solution to the climate crisis. In particular, the promising carbon sequestration potential of the ocean is being emphasised. In this paper, we seek to historicise the practices, discourses and actors that have constructed the ocean as a climate change solution space. We conceptualise the debate about the mitigation potential of the ocean as a contested site of governance, where varying actors form alliances and different sociotechnical narratives about climate action play out. Using an innovative quali-quantitative methodology which combines scientometrics with document analysis, observational fieldwork, and interviews, we outline three historical phases in the history of ocean carbon sequestration that follow recurring cycles of hype, controversy and disappointment. We argue that the most recent hype around ocean carbon sequestration was not triggered by a technological breakthrough or a reduction in scientific uncertainty, but by new socio-technical configurations and coalitions. We conclude by showing that how climate change solutions are put on the agenda and become legitimised is both a scientific and political process, linked to how science frames the climate crisis, and ultimately, its governance.
Continue reading ‘The rise, fall and rebirth of ocean carbon sequestration as a climate ‘solution’’Evaluating the values and limitations for coral and oyster reefs in coastal disaster risk reduction: a literature review
Published 12 March 2024 Science ClosedTags: mitigation, review, socio-economy
Previous researchers have made efforts to link the limitations and values of coral and oyster reefs to coastal defence. However, given the context in which reef ecosystems interact with changing climate and human behaviours, synthesising the available information is necessary to know the status and actions needed to improve the situation. To comprehend and advance this field, we used a detailed review approach to examine 84 relevant previous papers to provide a comprehensive overview of the existing state of knowledge of the values and limitations of coral and oyster reefs in coastal disaster risk reduction. The results show that the literature on the economic valuation of oyster reefs in coastal disaster risk reduction is in its infancy and therefore needs more attention. Due to the lower threshold of environmental tolerance of corals, the ongoing and projected global warming circumstances will put coral reefs more at risk than oyster reefs. The severity of the associated consequences for humans will depend on socioeconomic disparity and poor governance among coastal communities. Individuals who rely on climate-susceptible livelihoods will suffer the most. The authors recommend collaborative studies involving local governments to investigate the possibility of making payment for the services of these organisms a requirement for living near them. Additionally, simulation and modelling studies on the reactions of corals and oyster reefs to short, medium, and long-term projected climate change and human influences are necessary.
Continue reading ‘Evaluating the values and limitations for coral and oyster reefs in coastal disaster risk reduction: a literature review’Long non-coding RNAs mediate fish gene expression in response to ocean acidification
Published 8 March 2024 Science ClosedTags: biological response, fish, molecular biology, review
The majority of the transcribed genome does not have coding potential but these non-coding transcripts play crucial roles in transcriptional and post-transcriptional regulation of protein-coding genes. Regulation of gene expression is important in shaping an organism’s response to environmental changes, ultimately impacting their survival and persistence as population or species face global change. However, the roles of long non-coding RNAs (lncRNAs), when confronted with environmental changes, remain largely unclear. To explore the potential role of lncRNAs in fish exposed to ocean acidification (OA), we analyzed publicly available brain RNA-seq data from a coral reef fish Acanthochromis polyacanthus. We annotated the lncRNAs in its genome and examined the expression changes of intergenic lncRNAs (lincRNAs) between A. polyacanthus samples from a natural CO2 seep and a nearby control site. We identified 4728 lncRNAs, including 3272 lincRNAs in this species. Remarkably, 93.03% of these lincRNAs were species-specific. Among the 125 highly expressed lincRNAs and 403 differentially expressed lincRNAs in response to elevated CO2, we observed that lincRNAs were either neighboring or potentially trans-regulating differentially expressed coding genes associated with pH regulation, neural signal transduction, and ion transport, which are known to be important in the response to OA in fish. In summary, lncRNAs may facilitate fish acclimation and mediate the responses of fish to OA by modulating the expression of crucial coding genes, which offers insight into the regulatory mechanisms underlying fish responses to environmental changes.
Continue reading ‘Long non-coding RNAs mediate fish gene expression in response to ocean acidification’Science, international law, and policy across the air–sea interface
Published 7 March 2024 Science ClosedTags: policy, review
The objective of this perspective article is to determine the extent to which processes operating across the air–sea interface are considered in international environmental policy. The ocean is usually important but rarely a defining feature in such policies. We will begin with a brief introduction to the existing relevant treaties and policy frameworks. The provisions within these treaties will be analyzed for instances when air–sea interactions are considered and when they are not. We aim to establish that there is a lack of consideration in international regulation of the interaction between the atmosphere and the ocean, something that is not compatible with the environmental reality. Consequently, we point out examples where we think the air–sea interface could have been incorporated in international legislation. The question of why there is a gap between science and policy, regarding air–sea interactions, is posed and our hypotheses for the answers are outlined. The concept of so-called soft law and related instruments, such as the 2015 United Nations Sustainable Development Goals, are discussed. We finalize this review with our recommendations for future policymaking across the air–sea interface.
Continue reading ‘Science, international law, and policy across the air–sea interface’A high-resolution synthesis dataset for multistressor analyses along the U.S. West Coast (update)
Published 6 February 2024 Science ClosedTags: chemistry, North Pacific, review
Global trends of ocean warming, deoxygenation, and acidification are not easily extrapolated to coastal environments. Local factors, including intricate hydrodynamics, high primary productivity, freshwater inputs, and pollution, can exacerbate or attenuate global trends and produce complex mosaics of physiologically stressful or favorable conditions for organisms. In the California Current System (CCS), coastal oceanographic monitoring programs document some of this complexity; however, data fragmentation and limited data availability constrain our understanding of when and where intersecting stressful temperatures, carbonate system conditions, and reduced oxygen availability manifest. Here, we undertake a large data synthesis to compile, format, and quality-control publicly available oceanographic data from the US West Coast to create an accessible database for coastal CCS climate risk mapping, available from the National Centers for Environmental Information (accession 0277984) at https://doi.org/10.25921/2vve-fh39 (Kennedy et al., 2023). With this synthesis, we combine publicly available observations and data contributed by the author team from synoptic oceanographic cruises, autonomous sensors, and shore samples with relevance to coastal ocean acidification and hypoxia (OAH) risk. This large-scale compilation includes 13.7 million observations from 66 sources and spans 1949 to 2020. Here, we discuss the quality and composition of the synthesized dataset, the spatial and temporal distribution of available data, and examples of potential analyses. This dataset will provide a valuable tool for scientists supporting policy- and management-relevant investigations including assessing regional and local climate risk, evaluating the efficacy and completeness of CCS monitoring efforts, and elucidating spatiotemporal scales of coastal oceanographic variability.
Continue reading ‘A high-resolution synthesis dataset for multistressor analyses along the U.S. West Coast (update)’Reviews and syntheses: The clam before the storm – a meta-analysis showing the effect of combined climate change stressors on bivalves
Published 6 February 2024 Science ClosedTags: biological response, growth, mollusks, morphology, multiple factors, oxygen, review, salinity, temperature
The impacts of climate change on marine organisms have been increasingly documented in laboratory and experimental studies. However, the use of different taxonomic groupings and the assessment of a range of processes make identifying overall trends challenging. Meta-analysis has been used to determine general trends, but coarse taxonomic granularity may mask phylogenetically specific responses. Bivalve molluscs are a data-rich clade of ecologically and economically important calcifying marine taxa that allow for the assessment of species-specific vulnerability across developmental stages. Drawing on the large body of available literature, we conduct a meta-analysis of 203 unique experimental set-ups in order to examine how bivalve growth responds to increased water temperature, acidity, deoxygenation, and changes in salinity in 10 climate change stressor combinations. This is the most complete examination of bivalve responses to date and shows that anthropogenic climate change will disproportionally affect particular families, suggesting taxonomic differentiation in climate change response. Specifically, Mytilidae, Ostreidae, and Pectinidae (67 % of experiments) respond with negative effect sizes for all individual stressors, whereas responses in Pinnidae, Tellinidae, and Veneridae are more complex. Our analysis shows that earlier studies reporting negative impacts on bivalves are driven by only three or four well-studied, commercially important families. Despite the taxonomic differentiation, almost all drivers and their combinations have significant negative effects on growth. The synergistic impacts of deoxygenation, acidification, and temperature result in the largest negative effect size. Infaunal taxa, including Tellinidae and Veneridae, appear more resistant to warming and oxygen reduction than epifaunal or motile taxa, but this difference between the two taxa is also based on a small number of data points. The current focus of experimental set-ups on commercially important taxa and families within a small geographic range creates gaps in the understanding of global impacts on these economically important foundation organisms.
Continue reading ‘Reviews and syntheses: The clam before the storm – a meta-analysis showing the effect of combined climate change stressors on bivalves’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’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.
