An understanding of the combined effects of climate change and other anthropogenic stressors, such as chemical exposures, is essential for improving ecological risk assessments of vulnerable ecosystems. In the Great Barrier Reef, coral reefs are under increasingly severe duress from increasing ocean temperatures, acidification and cyclone intensities associated with climate change. In addition to these stressors, inshore reef systems, such as the Mackay Whitsunday coastal zone are being impacted by other anthropogenic stressors, including chemical, nutrient and sediment exposures related to more intense rainfall events that increase catchment runoff of contaminated waters. To illustrate an approach for incorporating climate change into ecological risk assessment frameworks, we developed an adverse outcome pathway network to conceptually delineate effects of climate variables and PSII herbicide (diuron) exposures on scleractinian corals. This informed the development of a Bayesian network to quantitatively compare the effects of historical (1975-2005) and future projected climate on inshore hard coral bleaching, mortality, and cover. This Bayesian network demonstrated how risk may be predicted for multiple physical and biological stressors including temperature, ocean acidification, cyclones, sediments, macroalgae competition, and crown of thorns starfish predation, as well as chemical stressors such as nitrogen and herbicides. Climate scenarios included an ensemble of 16 downscaled models encompassing current and future conditions based on multiple emission scenarios for two thirty-year periods. It was found that both climate-related and catchment-related stressors pose a risk to these inshore reef systems, with projected increases in coral bleaching and coral mortality under all future climate scenarios. This modelling exercise can support the identification of risk drivers for the prioritisation of management interventions to build future resilient reefs.
Continue reading ‘Evaluating the effects of climate change and chemical, physical and biological stressors on nearshore coral reefs: a case study in the Great Barrier Reef, Australia’Archive Page 92
Evaluating the effects of climate change and chemical, physical and biological stressors on nearshore coral reefs: a case study in the Great Barrier Reef, Australia
Published 15 December 2023 Science ClosedTags: biological response, communitymodeling, corals, modeling, South Pacific
Atlantic Ocean near Bermuda is warmer and more acidic than ever, 40 years of observation show
Published 15 December 2023 Press releases ClosedDecade-long ocean warming that impacts ocean circulation, a decrease in oxygen levels that contributes to changes in salinification and nutrient supply, and ocean acidification are just some of the challenges the world’s oceans are facing.
In 1988, a comprehensive sustained ocean time-series of observations, called the Bermuda Atlantic Time-series Study (BATS), began at a site about 80 km southeast of the island of Bermuda. There, scientists take monthly samples of the physics, biology, and chemistry of the ocean’s surface and depths.
In a new paper published in Frontiers in Marine Science, researchers have now presented the latest findings from this monitoring effort.
Continue reading ‘Atlantic Ocean near Bermuda is warmer and more acidic than ever, 40 years of observation show’Physio-biochemical and metabolomic analyses of the agarophyte Gracilaria salicornia indicates its tolerance to elevated pCO2 levels
Published 14 December 2023 Science ClosedTags: abundance, algae, biological response, growth, Indian, laboratory, otherprocess, photosynthesis, physiology
Gracilaria salicornia is an agar-producing red macroalga commonly found growing in the intertidal and upper subtidal on various substrates with distribution across the Indo-Pacific. The ability of G. salicornia to survive under harsh conditions suggests potential use as a candidate for sustainable farming and alternative source of livelihood for the local coastal communities under future climate conditions. An earlier study investigated the effects of future predicted pCO2 level on the photosynthesis and respiration of G. salicornia but studies on the metabolomic responses of this alga to constant elevated pCO2 level is lacking. Here, elevated pCO2 level was simulated on G. salicornia for 14 days to compare its growth, photosynthetic efficiency, pigment content, agar properties and metabolite composition under current pCO2 level (∼pH 8.1) and end-of-century future-predicted (∼pH 7.8) pCO2 level. The observed biomass growth, coupled with unaffected photosynthetic parameters and agar-related properties underscore G. salicornia’s ability to adapt to higher pCO2 levels. The modulation of metabolites showcases the alga’s adaptive strategies at elevated pCO2 whereby stress-mediating compounds such as gallic acid and oxalic acid were increased while stress-indicating metabolites such as serine, glycine, and ascorbic acid did not show significant changes. Interestingly, the metabolome profile imply that the alga regulates its metabolism according to culture duration rather than the pCO2 level.
Continue reading ‘Physio-biochemical and metabolomic analyses of the agarophyte Gracilaria salicornia indicates its tolerance to elevated pCO2 levels’Forty years of ocean acidification observations (1983–2023) in the Sargasso Sea at the Bermuda Atlantic Time-series Study site
Published 14 December 2023 Science ClosedTags: chemistry, field, North Atlantic
Ocean physical and biogeochemical conditions are rapidly changing over time. Forty years of observations from 1983 to 2023 collected at the Bermuda Atlantic Time-series Study (BATS) site near Bermuda in the North Atlantic Ocean shows continuing trends of surface warming, increase in salinity, loss of dissolved oxygen (DO), increase in carbon dioxide (CO2), and ocean acidification (OA) effects. Over this period, the ocean has warmed by about +1°C, increased in salinity by +0.136, and lost DO by 12.5 µmol kg−1 or ~6%. Since the 1980s, ocean dissolved inorganic carbon (DIC), total alkalinity (TA), a tracer of anthropogenic CO2 (CTrOCA), and fugacities/partial pressures of CO2 (i.e., fCO2 and pCO2) have continued to increase substantially, with no evidence of a reduction in the rates of change over time. Contemporaneously, ocean pH has decreased by ~0.1 pH units [with ocean acidity (i.e., H+) increasing by >30%], and the saturation states of calcium carbonate minerals (Ωcalcite and Ωaragonite) have decreased. These OA indicators show that the chemical conditions for calcification have become less favorable over the past 40 years. Updating of data and trends at the BATS site show how ocean chemistry of the 2020s is now outside the range observed in the 1980s, and how essential these data are for predicting the response of ocean chemistry and marine ecosystems to future shifting earth and ocean conditions.
Continue reading ‘Forty years of ocean acidification observations (1983–2023) in the Sargasso Sea at the Bermuda Atlantic Time-series Study site’COP28 session – Ocean Carbon Dioxide Removal: Science, Governance and Policy for safe and transparent implementation
Published 14 December 2023 Events , Presentations ClosedThe ocean is the planets’ largest carbon reservoir. Interest in using marine spaces to facilitate CDR for climate change mitigation must be based on solid science and address environmental impacts, risks, co-benefits, technical feasibility, cost effectiveness and political/societal acceptance.
Speakers: Christopher Pearce (NOC, UK); Shaun Fitzgerald (Cambridge, UK); Ken Buesseler (WHOI, USA); David Koweek (Ocean Visions, USA); Margret Leinen (Scripps, USA); Paul Holtus (WOC, USA); Sarah Cooley (Ocean Conservancy, USA); Nianzhi Jiao (Xiamen, China); Miranda Böttcher (SWP, Germany)
UN Climate Change – Events, YouTube, 11 December 2023. Video & text.
Multi-proxy record of the mid-Maastrichtian event in the European Chalk Sea: paleoceanographic implications
Published 13 December 2023 Science ClosedTags: Baltic, chemistry, field, paleo, sediment
The Cretaceous provides us with an excellent case history of ocean-climate-biota system perturbations. Such perturbations occurred several times during the Cretaceous, such as oceanic anoxic events and the end-Cretaceous mass extinction, which have been the subject of an abundant literature. Other perturbations, such as the mid-Maastrichtian Event (MME) remain poorly understood. The MME was associated with global sea-level rise, changes in climate and deep-water circulation that were accompanied by biotic extinctions including “true” inoceramids and the demise of the Caribbean-Tethyan rudist reef ecosystems. So far, the context and causes behind the MME remain poorly studied. We conducted high-resolution integrated biotic, petrological and geochemical studies in order to fill this knowledge gap. We studied, in particular, carbonate Nd and Os isotopes, whole-rock Hg, C and N content, C and N isotopes in organic matter, SCAS isotopes, along with C and O isotopes from foraminifera from the European Chalk Sea: the Polanówka UW-1 core from Poland and the Stevns-1 core from Denmark. Our data showed that sea-level rise of ∼50-100 m lasted around ∼2 Ma and co-occurred with anomalously high mercury concentration. Along with previously published data, our results strongly suggest that the MME was driven by intense volcanic–tectonic activity, likely related to the production of vast oceanic plateaus (LIP, Large Igneous Province). The collapse of reef ecosystems could have been the consequence of LIP-related environmental stress factors, including climate warming, presumably caused by emission of greenhouse gases, modification of the oceanic circulation, oceanic acidification and/or toxic metal input. The disappearance of the foraminifer Stensioeina lineage on the European shelf was likely caused by the collapse of primary production triggered by sea-level rise and limited amount of nutrient input. Nd isotopes and foraminiferal assemblages attest for changes in sea-water circulation in the European Shelf and the increasing contribution of North Atlantic water masses.
Continue reading ‘Multi-proxy record of the mid-Maastrichtian event in the European Chalk Sea: paleoceanographic implications’Job opportunity: Ocean Acidification Program Technician, Mote Marine Laboratory
Published 13 December 2023 Uncategorized ClosedDeadline for applications: 22 December 2023
Location: Summerland Key, FL, USA
The Ocean Acidification (OA) Program at the Mote Marine Laboratory Elizabeth Moore International Center for Coral Reef Research and Restoration (IC2R3) located on Summerland Key, FL seeks a technician position to be filled as soon as possible. This position will report directly to the OA Program Lab Manager within the OA Program. General duties to be performed include analyses of dissolved inorganic carbon (DIC), total alkalinity, spectrophotometric pH, and colorimetry; participation in field sampling; operations from trucks or boats; occasional evening/night shifts, depending on project demands; and assisting IC2R3 with lab tours and other outreach events (as needed). Activities in this program are carried out according to the Mote Marine Lab Quality Plan including operation and maintenance of scientific equipment, preparations for field trips, sample analyses, and data quality assessments. The majority of this position will be chemistry lab-based and will require work with hazardous substances, laboratory cleaning, instrument maintenance, experimental work, and data collection. Some projects will require time on a research vessel offshore but will be limited.
Continue reading ‘Job opportunity: Ocean Acidification Program Technician, Mote Marine Laboratory’Mentoring the next generation of ocean deoxygenation and acidification scientists
Published 13 December 2023 Courses and training ClosedUNESCO’s Intergovernmental Oceanographic Commission (IOC/UNESCO), El Centro de Estudios Avanzados en Zonas Áridas (CEAZA) and the Universidad Catolica del Norte, as well as many other partners and sponsors organized the GOOD-OARS-CLAP-COPAS Summer School from 6-12 November 2023 in La Serena, Chile to teach the latest science of ocean acidification and deoxygenation.
This marks the second such school, following its occurrence in Xiamen, China, 2019.
The school concept is a creation of two IOC-supported expert groups, the Global Ocean Oxygen Network (GO2NE) and the Global Ocean Acidification Network (GOA-ON). These groups are committed to providing a global and multidisciplinary view of deoxygenation and ocean acidification, focusing on enhancing understanding of their multiple aspects and cumulative impacts. The networks offer scientific advice to policy makers to preserve marine resources in the presence of acidification and deoxygenation.
They teamed up with two affiliated UN Decade of Ocean Science for Sustainable Development programmes, the Global Ocean Oxygen Decade (GOOD) and the Ocean Acidification Research for Sustainability (OARS), to develop the summer school framework as a means to engage early career ocean professionals.
Continue reading ‘Mentoring the next generation of ocean deoxygenation and acidification scientists’The IAEA Coordinated Research Project (CRP) “Evaluating the Impact of Ocean Acidification on Seafood – a Global Approach” concludes its 5-year work
Published 12 December 2023 Meetings , Projects Closed
The IAEA Coordinated Research Project (CRP) “Evaluating the Impact of Ocean Acidification on Seafood – a Global Approach”, supported by the Ocean Acidification International Coordination Centre (OA-ICC), conducted its final meeting on 4-7 December 2023 at the IAEA Marine Environment Laboratories in Monaco. Spanning over a period of five years (2018-2023), the project brought together scientists affiliated with research institutions from 14 IAEA Member States (Argentina, Bahamas, Brazil, Costa Rica, Cuba, Ecuador, Egypt, Kenya, Lebanon, Mexico, Morocco, Sweden, Thailand, Turkey), creating a joint platform for collaboration on a project of shared interest in the area of seafood security with broader socio-economic implications.
Using a jointly agreed research protocol developed at the first project meeting in Sweden in 2019, all participating scientists embarked on a long-term laboratory experiment (8 months) on select species of particular economic, social and cultural relevance for their countries. A total of 16 species – from mollusks and crustaceans to echinoderms and fish – were submitted to lower pH treatments to assess the impact of ocean acidification on organism development and performance, observe existing resilience and/or adaptation pathways and prompt potential local aquaculture measures and vaster global mitigation solutions.
Continue reading ‘The IAEA Coordinated Research Project (CRP) “Evaluating the Impact of Ocean Acidification on Seafood – a Global Approach” concludes its 5-year work’Temporal variations in the surface aragonite saturation state of the Yellow Sea: observations at the Socheongcho Ocean Research Station during 2017–2022
Published 12 December 2023 Science ClosedTags: chemistry, field, North Pacific
Highlights
- Aragonite saturation (ΩAR) in the Yellow Sea showed significant seasonal fluctuations.
- Seasonal trends in ΩAR were shaped by physical mixing and biological production.
- The dynamic nature highlights the importance of continuous monitoring.
Abstract
Accurately constraining the natural variability of the carbonate system is essential for evaluating long-term changes in coastal areas, which result from the absorption of anthropogenic CO2. This is particularly important given the significant variation in physical and biological processes in these regions. In this regard, the analysis of surface carbonate chemistry in the Yellow Sea was conducted using discrete seawater samples obtained from the Socheongcho Ocean Research Station (37.423°N, 124.738°E) between 2017 and 2022. Our bottle data and sensor pH measurements revealed considerable seasonal variations of aragonite saturation state (ΩAR), typically ranging from 1.6 to 3.9. These variations are particularly pronounced during the summer and early winter. Our dataset serves as a baseline for understanding the long-term changes in ocean acidification in the Yellow Sea, the complex biogeochemical processes in coastal areas, and their impact on ocean acidification.
Continue reading ‘Temporal variations in the surface aragonite saturation state of the Yellow Sea: observations at the Socheongcho Ocean Research Station during 2017–2022’Seawater carbonate chemistry considerations for ocean alkalinity enhancement research: theory, measurements, and calculations
Published 11 December 2023 Science ClosedTags: chemistry, methods, mitigation
Ocean alkalinity enhancement (OAE) is a proposed marine carbon dioxide removal (mCDR) approach that has the potential for large-scale uptake of significant amounts of atmospheric carbon dioxide (CO2). Removing anthropogenic legacy CO2 will be required to stabilise global surface temperatures below the 1.5–2 ∘C Paris Agreement target of 2015. In this chapter we describe the impacts of various OAE feedstocks on seawater carbonate chemistry, as well as pitfalls that need to be avoided during sampling, storage, and measurement of the four main carbonate chemistry parameters, i.e. dissolved inorganic carbon (DIC), total alkalinity (TA), pH, and CO2 fugacity (fCO2). Finally, we also discuss considerations in regard to calculating carbonate chemistry speciation from two measured parameters. Key findings are that (1) theoretical CO2 uptake potential (global mean of 0.84 mol of CO2 per mole of TA added) based on carbonate chemistry calculations is probably secondary in determining the oceanic region in which OAE would be best; (2) carbonate chemistry sampling is recommended to involve gentle pressure filtration to remove calcium carbonate (CaCO3) that might have been precipitated upon TA increase as it would otherwise interfere with a number of analyses; (3) samples for DIC and TA can be stabilised to avoid the risk of secondary CaCO3 precipitation during sample storage; and (4) some OAE feedstocks require additional adjustments to carbonate chemistry speciation calculations using available programs and routines, for instance if seawater magnesium or calcium concentrations are modified.
Continue reading ‘Seawater carbonate chemistry considerations for ocean alkalinity enhancement research: theory, measurements, and calculations’Monitoring, reporting, and verification for ocean alkalinity enhancement
Published 11 December 2023 Science ClosedTags: methods, mitigation, modeling
Monitoring, reporting, and verification (MRV) refers to the multistep process of monitoring the amount of greenhouse gas removed by a carbon dioxide removal (CDR) activity and reporting the results of the monitoring to a third party. The third party then verifies the reporting of the results. While MRV is usually conducted in pursuit of certification in a voluntary or regulated CDR market, this chapter focuses on key recommendations for MRV relevant to ocean alkalinity enhancement (OAE) research. Early stage MRV for OAE research may become the foundation on which markets are built. Therefore, such research carries a special obligation toward comprehensiveness, reproducibility, and transparency. Observational approaches during field trials should aim to quantify the delivery of alkalinity to seawater and monitor for secondary precipitation, biotic calcification, and other ecosystem changes that can feed back on sources or sinks of greenhouse gases where alkalinity is measurably elevated. Observations of resultant shifts in the partial pressure of CO2 (pCO2) and ocean pH can help determine the efficacy of OAE and are amenable to autonomous monitoring. However, because the ocean is turbulent and energetic and CO2 equilibration between the ocean and atmosphere can take several months or longer, added alkalinity will be diluted to perturbation levels undetectable above background variability on timescales relevant for MRV. Therefore, comprehensive quantification of carbon removal via OAE will be impossible through observational methods alone, and numerical simulations will be required. The development of fit-for-purpose models, carefully validated against observational data, will be a critical part of MRV for OAE.
Continue reading ‘Monitoring, reporting, and verification for ocean alkalinity enhancement’Ocean acidification creates legacy of stress for red abalone: reducing exposure at crucial stages can help save red abalone
Published 11 December 2023 Press releases Closed
Stressful childhoods can affect an individual’s adult years and influence future generations. Scientists at the University of California, Davis, found a similar pattern holds true for red abalone exposed as babies, and again as adults, to the stress of ocean acidification.
Their study, published in the journal Global Change Biology, found that the negative impacts of ocean acidification — a byproduct of carbon dioxide emissions — on red abalone can last within and across generations. Buffering against ocean acidification at crucial life stages can help ease these effects for captive- and commercially raised red abalone, while informing efforts to conserve wild abalone, the study said.
“For red abalone, if your parents were exposed to ocean acidification, it does impact your ability to handle stress,” said lead author Isabelle Neylan, a Ph.D. student at UC Davis Bodega Marine Laboratory when the study was conducted and currently a postdoctoral researcher at Louisiana State University. “It’s carrying over within that generation and on to the next generation.”
Continue reading ‘Ocean acidification creates legacy of stress for red abalone: reducing exposure at crucial stages can help save red abalone’Carbon capture startups dive for climate solutions in the ocean
Published 11 December 2023 Media coverage ClosedAs money pours into companies promising to take greenhouse gasses out of the atmosphere, there’s a small but fast-growing sector of startups that want to leverage one of the world’s biggest carbon sinks to clean up humanity’s climate pollution: the ocean. For our series Reverse Course, Chris Bentley reports on some of the scientists and entrepreneurs developing ways to enhance the ocean’s natural ability to take carbon dioxide out of the atmosphere.
And, researchers at the Pacific Northwest National Lab are also looking into how native eelgrass could fight ocean acidification, and how algae could offset carbon emissions in the construction industry. Bentley tells us more.
Then, NPR’s Aya Batrawy shares the latest from the COP28 summit in Dubai.
Continue reading ‘Carbon capture startups dive for climate solutions in the ocean’Assessing seasonal and interannual changes in carbonate chemistry across two time-series sites in the North Western Mediterranean Sea
Published 8 December 2023 Science ClosedTags: chemistry, field, Mediterranean
Sustained time-series measurements are crucial to understand changes in oceanic carbonate chemistry. In the North Western Mediterranean Sea, the temporal evolution of the carbonate system is here investigated based on two 10-year time-series (between January 2010 and December 2019) of monthly carbonate parameters measurements at two sampling sites in the Ligurian Sea (ANTARES and DYFAMED). At seasonal timescale, the seawater partial pressure of CO2 (pCO2) within the mixed layer is mostly driven by temperature at both sites, and biological processes as stated by the observed relationships between total inorganic carbon (CT), nitrate and temperature. This study suggests also that mixing and water masses advection could play a role in modulating the CT content. At decadal timescale, significant changes in ocean chemistry are observed with increasing trends in CT (+3.2 ± 0.9 µmol.kg−1.a−1 – ANTARES; +1.6 ± 0.8 µmol.kg−1.a−1 – DYFAMED), associated with increasing pCO2 trends and decreasing trends in pH. The magnitude of the increasing trend in CT at DYFAMED is consistent with the increase in atmospheric pCO2 and the anthropogenic carbon transport of water originating from the Atlantic Ocean, while the higher trends observed at the ANTARES site could be related to the hydrological variability induced by the variability of the Northern Current.
Continue reading ‘Assessing seasonal and interannual changes in carbonate chemistry across two time-series sites in the North Western Mediterranean Sea’Higher temperature, increased CO2, and changing nutrient ratios alter the carbon metabolism and induce oxidative stress in a cosmopolitan diatom
Published 8 December 2023 Science ClosedTags: biological response, growth, laboratory, multiple factors, North Atlantic, nutrients, photosynthesis, physiology, phytoplankton, primary production, respiration, temperature
Phytoplankton are responsible for about 90% of the oceanic primary production, largely supporting marine food webs, and actively contributing to the biogeochemical cycling of carbon. Yet, increasing temperature and pCO2, along with higher dissolved nitrogen: phosphorus ratios in coastal waters are likely to impact phytoplankton physiology, especially in terms of photosynthetic rate, respiration, and dissolved organic carbon (DOC) production. Here, we conducted a full-factorial experiment to identify the individual and combined effects of temperature, pCO2, and N : P ratio on the antioxidant capacity and carbon metabolism of the diatom Phaeodactylum tricornutum. Our results demonstrate that, among these three drivers, temperature is the most influential factor on the physiology of this species, with warming causing oxidative stress and lower activity of antioxidant enzymes. Furthermore, the photosynthetic rate was higher under warmer conditions and higher pCO2, and, together with a lower dark respiration rate and higher DOC exudation, generated cells with lower carbon content. An enhanced oceanic CO2 uptake and an overall stimulated microbial loop benefiting from higher DOC exudation are potential longer-term consequences of rising temperatures, elevated pCO2 as well as shifted dissolved N : P ratios.
Continue reading ‘Higher temperature, increased CO2, and changing nutrient ratios alter the carbon metabolism and induce oxidative stress in a cosmopolitan diatom’Spatiotemporal variation of China’s mariculture potential under climate change
Published 8 December 2023 Science ClosedTags: biological response, fish, fisheries, growth, modeling, mollusks, morphology, North Pacific, regionalmodeling
Being the world’s largest seafood producer, China’s mariculture is critical for ensuring national and global food security, yet greatly threatened by climate change. It is essential to assess the potential opportunities and challenges for Chinese mariculture in light of climate change. Although the impact of climate change on mariculture potential at a global scale has been investigated, studies at sub-national scales of China are scarce, particularly those that take into account multiple environmental stressors and species. Here, we applied a combination of physical and biological models to quantify the spatiotemporal variation in the mariculture potential of seven finfish species and seven bivalve species cultured in China under the emission scenarios SSP5-8.5 and SSP1-2.6 in the twentyfirst century. Our results demonstrated that the spatiotemporal trends in culture potential was species-specific. Finfish was less affected than bivalves. Four finfish species and seven bivalve species showed a continuously declining trend in culture potential and most species showed a northward shift of the centroid with high growth potential under SSP5-8.5. Under the scenario SSP1-2.6, the culture potential of finfish species mostly showed a stable or increasing trend, while that of bivalve species declined in the mid-twentyfirst century and partially recovered in the late twentyfirst century. Cold-water species exhibited a greater loss of culture potential than warm-water and eurythermal species. In the SSP5-8.5 and SSP1-2.6 scenarios, the cold-water species Oncorhynchus mykiss and Patinopecten yessoensis experienced the most significant loss in culture potential among finfish and bivalve species. Meanwhile, the culture potential for two out of the four warm-water species, specifically Epinephelus spp. and Sciaenops ocellatus, saw an increase. The culture potential for eight eurythermal species remained stable or declined. This study helps to identify mariculture potential for different species and sea areas and can inform the development of climate-resilient mariculture in China.
Continue reading ‘Spatiotemporal variation of China’s mariculture potential under climate change’Emergent properties of free-living nematode assemblages exposed to multiple stresses
Published 7 December 2023 Science ClosedTags: abundance, biological response, BRcommunity, community composition, laboratory, mesocosms, metals, multiple factors, nematodes, otherprocess, sediment, South Atlantic, temperature
Highlights
- Co-occurring stressors have significant interactive effects on nematode assemblages.
- Metal contamination surpasses the effects of temperature rise and acidification.
- Temperature rise intensified contamination effects on nematodes.
- Acidification acted as a buffer to the contamination effects on nematodes.
- Nematode genera showed variable responses to contamination.
Abstract
Biological communities are currently facing multi-stressor scenarios whose ecological impacts are challenging to estimate. In that respect, considering the complex nature of ecosystems and types and interaction among stressors is mandatory. Microcosm approaches using free-living nematode assemblages can effectively be used to assess complexity since they preserve the interactions inherent to complex systems when testing for multiple stress effects. In this study, we investigated the interaction effects of three stress factors, namely i-metallic mixture of Cu, Pb, Zn, and Hg (control [L0], low, [L1] and high [L2]), ii- CO2-driven acidification (pH 7.6 and 8.0), and iii- temperature rise (26 and 28 °C), on estuarine free-living nematode assemblages. Metal contamination had the greatest influence on free-living nematode assemblages, irrespective of pH and temperature scenarios. Interestingly, whilst the most abundant free-living nematode genera showed significant decreases in their densities when exposed to contamination, other, less abundant, genera were apparently favored and showed significantly higher densities in contaminated treatments. The augmented densities of tolerant genera may be attributed to indirect effects resulting from the impacts of toxicity on other components of the system, indicating the potential for emergent effects in response to stress. Temperature and pH interacted significantly with contamination. Whilst temperature rise had potentialized contamination effects, acidification showed the opposite trend, acting as a buffer to the effects of contamination. Such results show that temperature rise and CO2-driven acidification interact with contamination on coastal waters, highlighting the importance of considering the intricate interplay of these co-occurring stressors when assessing the ecological impacts on coastal ecosystems.
Continue reading ‘Emergent properties of free-living nematode assemblages exposed to multiple stresses’Phanerozoic oceanic and climatic perturbations in the context of Tethyan evolution
Published 7 December 2023 Science ClosedTags: chemistry, paleo, review
Climatic and environmental conditions play a pivotal role in the evolution of the biosphere, serving as the primary natural factors influencing biological evolution and the development of human civilization. The study of the evolution of Earth’s habitability primarily revolves around the reconstruction of climatic and oceanic conditions in geohistorical periods, shedding light on their dynamic changes. This paper collates classic geological indicators and geochemical proxies associated with paleo-climatic and oceanic environmental conditions. The latest “big data” analyses and simulations made possible by the availability of previously unimagined massive datasets reveal several key findings: During the early Paleozoic, atmospheric oxygen levels were low, and widespread oceanic anoxia was prevalent; the Devonian era witnessed a greenhouse climate, followed by the Carboniferous ice age characterized by higher oceanic oxidation levels and alkalinity. The latest Paleozoic deglaciation occurred under high pCO2 conditions, extending into much of the Mesozoic and early Cenozoic, marked by multiple hyperthermal and anoxia expansion events, until the resurgence of global glaciation in the middle-late stages of the Cenozoic, ultimately bringing environmental and climatic conditions closer to modern levels. By correlating the aforementioned long-term trends with major geological events, we can delineate the co-evolution of paleoclimate and oceanic environments in tandem with the development of Tethys tectonics as follows. (1) During the Proto-Tethys stage, global paleo-elevations were relatively low, and atmospheric oxygen levels were also relatively modest. Despite the occurrence of significant tectonic movements that led to noticeable transgressive-regressive cycles, their effects on climate and oceanic environments were somewhat limited due to the relatively weak interactions. (2) The emergence of the Paleo-Tethys was a significant event that coincided with the formation of the supercontinent Pangaea. Intensive orogenic movements during this period increased the global land area and elevation. This, in turn, led to enhanced terrestrial weathering, which elevated sea surface productivity and resulted in massive nutrient input into the oceans. Consequently, this process contributed to the rise of oxygen levels in the atmosphere and a decrease in atmospheric pCO2. These changes are considered potential driving mechanisms for late Paleozoic glaciation and oceanic oxygenation. (3) The transition from the Paleo-Tethys to the Neo-Tethys was closely linked to the breakup of Pangaea. During this period, the terrestrial weathering processes were relatively weak due to decreased continental elevations. This resulted in a long-term greenhouse climate and intermittent global oceanic events, which were responses to the high atmospheric pCO2 levels during the Mesozoic and early Cenozoic eras. (4) The Neo-Tethys stage ended with the dramatic uplift of the Alps-Himalaya Mountain ranges due to the collision of India and Asia. This uplift had a profound global impact, significantly increasing continental elevations. As a result, weathering and carbon burial processes intensified, leading to a reduction in atmospheric pCO2. Concurrently, this uplift played a crucial role in the establishment of the East Asian monsoon and North Atlantic deep-water circulations, both of which played a part in triggering the late Cenozoic ice age. These models suggest that the teleconnections between land and sea (orogeny-terrestrial weathering-marine carbon burial) span over the whole Phanerozoic and might have played a key role in balancing the Earth surface system. Combined, the tectonic, volcanic, paleo-climatic, as well as paleoenvironmental events recorded in the Tethys oceans and adjunct continents represent valuable natural experiments and lessons for understanding the present and the future of Earth’s habitability.
Continue reading ‘Phanerozoic oceanic and climatic perturbations in the context of Tethyan evolution’Electrochemical ocean alkalinity enhancement using a calcium ion battery
Published 6 December 2023 Science ClosedTags: chemistry, laboratory, methods
The oceans play a major role in moderating atmospheric CO2 levels. Enhanced CO2 uptake into ocean waters can be achieved by the provision of appropriate cations to the surface ocean, an approach known as ocean alkalinity enhancement (OAE). Here, we present a calcium ion battery approach that enhances alkalinity via electrochemical manipulation of seawater calcium concentrations. We demonstrate the efficacy of this approach using a potassium barium iron cyanide [K2BaFe(CN)6] (PBFC) electrode, a Prussian blue analogue, to move calcium ions from one reservoir of seawater to another. Using material and electrochemical characterization of the Ca2+ ion insertion and expulsion properties of PBFC in synthetic seawater, we determine the repeatability of Ca2+ ion insertion and expulsion from the PBFC electrode. Our analyses prove a 2.75 % increase in seawater alkalinity via the PBFC electrode, which yields 2.64 mg CO2 (0.72 mg C) uptake per liter of seawater. This proof-of-concept method offers a unique, low-cost, energy efficient electrochemical approach for atmospheric carbon dioxide removal that can combine with marine-based renewable energy to enable a new family of effective, scalable climate change solutions.
Continue reading ‘Electrochemical ocean alkalinity enhancement using a calcium ion battery’
