Increasing anthropogenic CO2 emissions in recent decades cause ocean acidification (OA), affecting carbon cycling in oceans by regulating eco-physiological processes of plankton. Heterotrophic bacteria play an important role in carbon cycling in oceans. However, the effect of OA on bacteria in oceans, especially in oligotrophic regions, was not well understood. In our study, the response of bacterial metabolic activity and community composition to OA was assessed by determining bacterial production, respiration, and community composition at the low-pCO2 (400 ppm) and high-pCO2 (800 ppm) treatments over the short term at two oligotrophic stations in the northern South China Sea. Bacterial production decreased significantly by 17.1–37.1 % in response to OA, since bacteria with high nucleic acid content preferentially were repressed by OA, which was less abundant under high-pCO2 treatment. Correspondingly, shifts in bacterial community composition occurred in response to OA, with a high fraction of the small-sized bacteria and high bacterial species diversity in a high-pCO2 scenario at K11. Bacterial respiration responded to OA differently at both stations, most likely attributed to different physiological responses of the bacterial community to OA. OA mitigated bacterial growth efficiency, and consequently, a larger fraction of DOC entering microbial loops was transferred to CO2.
Continue reading ‘Effect of ocean acidification on bacterial metabolic activity and community composition in oligotrophic oceans, inferred from short-term bioassays’Archive for February, 2021
Effect of ocean acidification on bacterial metabolic activity and community composition in oligotrophic oceans, inferred from short-term bioassays
Published 26 February 2021 Science ClosedTags: abundance, biological response, community composition, field, laboratory, molecular biology, North Pacific, otherprocess, performance, photosynthesis, physiology, primary production, prokaryotes, respiration
Impact of ocean acidification on ecosystem functioning and services in habitat-forming species and marine ecosystems
Published 26 February 2021 Science ClosedTags: abundance, biological response, BRcommunity, community composition, corals, otherprocess
Ocean acidification (OA) is expected to impact habitat-forming species (HFS), with cascading effects on the whole marine ecosystem and related services that are seldom quantified. Here, the changes in HFSs biomass due to OA are modeled using a food web ecosystem model, and the trophic and non-trophic cascading effects on the marine community are investigated. The food web model represents a well-studied coastal marine protected area in the NW Mediterranean Sea where coralligenous reefs and Posidonia oceanica meadows constitute important HFS. The model is used to implement 5 scenarios of habitat degradation, that is, reduction of HFS biomass, induced by increasing OA and to quantify the potential changes in ecosystem properties and indicators of ecosystem services over the next 100 years. The changes in ecosystem indicators highlight a decrease in the size of the system and a reorganization of energy flows suggesting a high degree of ecosystem development. All the proxies for ecosystem services show significant decreases in their values. Although representing only a portion of the possible impacts of OA, the findings are consistent with the idea that ecological systems can react to OA effects to maintain the level of ecosystem development, but the new organization might not be optimal from an anthropocentric viewpoint.
Continue reading ‘Impact of ocean acidification on ecosystem functioning and services in habitat-forming species and marine ecosystems’Turning up the lights: ocean acidification may increase light intensity of secretory bioluminescent signaling (text & video)
Published 26 February 2021 Presentations , Web sites and blogs ClosedVideo created by Tom Iwanicki, PhD Candidate at the University of Hawai’i at Manoa, presented at the annual meeting of the Society for Integrative and Comparative Biology in January 2021 through February 2021. These data are unpublished.
Synopsis: Approximately 75% of pelagic organisms are capable of bioluminescence. Under the IPCC worst-case scenario (RCP8.5), the average ocean pH will decrease from its pre-industrial average of 8.2 to 7.7 by the end of the 21st century. Under these conditions, bioluminescent systems may be affected by this change in the reaction medium (ocean water). This meta-analysis surveyed previously published research and found 49 records including bioluminescent intensity and pH for a wide range of taxa. These data suggest the direction and magnitude of an ocean acidification effect is taxa-specific.
Continue reading ‘Turning up the lights: ocean acidification may increase light intensity of secretory bioluminescent signaling (text & video)’Invariant gametogenic response of dominant infaunal bivalves from the Arctic under ambient and near-future climate change conditions
Published 26 February 2021 Science ClosedTags: biological response, laboratory, mollusks, morphology, multiple factors, reproduction, temperature
Arctic marine ecosystems are undergoing a series of major rapid adjustments to the regional amplification of climate change, but there is a paucity of knowledge about how changing environmental conditions might affect reproductive cycles of seafloor organisms. Shifts in species reproductive ecology may influence their entire life-cycle, and, ultimately, determine the persistence and distribution of taxa. Here, we investigate whether the combined effects of warming and ocean acidification based on near-future climate change projections affects the reproductive processes in benthic bivalves (Astarte crenata and Bathyarca glacialis) from the Barents Sea. Both species present large oocytes indicative of lecithotrophic or direct larval development after ∼4 months exposure to ambient [<2°C, ∼400 ppm (CO2)] and near-future [3–5°C, ∼550 ppm (CO2)] conditions, but we find no evidence that the combined effects of acidification and warming affect the size frequency distribution of oocytes. Whilst our observations are indicative of resilience of this reproductive stage to global changes, we also highlight that the successful progression of gametogenesis under standard laboratory conditions does not necessarily mean that successful development and recruitment will occur in the natural environment. This is because the metabolic costs of changing environmental conditions are likely to be offset by, as is common practice in laboratory experiments, feeding ad libitum. We discuss our findings in the context of changing food availability in the Arctic and conclude that, if we are to establish the vulnerability of species and ecosystems, there is a need for holistic approaches that incorporate multiple system responses to change.
Continue reading ‘Invariant gametogenic response of dominant infaunal bivalves from the Arctic under ambient and near-future climate change conditions’Technical note: interpreting pH changes (update)
Published 26 February 2021 Science ClosedTags: chemistry, methods
The number and quality of ocean pH measurements have increased substantially over the past few decades such that trends, variability, and spatial patterns of change are now being evaluated. However, comparing pH changes across domains with different initial pH values can be misleading because a pH change reflects a relative change in the hydrogen ion concentration ([H+], expressed in mol kg−1) rather than an absolute change in [H+]. We recommend that [H+] be used in addition to pH when describing such changes and provide three examples illustrating why.
Continue reading ‘Technical note: interpreting pH changes (update)’Warm and bubbly: increasing ocean CO2 and temperature affect fish distribution
Published 26 February 2021 Web sites and blogs Closed
Based on the paper: Ocean acidification may slow the pace of tropicalization of temperate fish communities by Ericka O. C. Coni, Ivan Nagelkerken, Camilo M. Ferreira, Sean D. Connell & David J. Booth. Nature Climate Change (2021) https://www.nature.com/articles/s41558-020-00980-
Ocean warming is causing range-extensions of warm-adapted species into temperate waters, but the effects of ocean acidification on this process are largely unknown. Laboratory test are informative but cannot incorporate the ecological complexity of nature. We therefore used ecosystems experiencing natural warming and acidification as analogues of future climate to predict the future rate of tropicalization of temperate ecosystems.
Imagine if you find yourself in a place that you are not familiar with. A place where you are not adapted to the local climate and culture. What should you do to blend in? You must think of new ways to succeed under these new circumstances. This situation is similar to that of hundreds of tropical fish species (tropical vagrant fishes) that are extending their ranges to cooler, temperate regions as the ocean warms. For at least two decades, Australian temperate reefs have been receiving new guests from the tropics, but their successful colonisation depends on how they respond to and cope with unfamiliar conditions. Temperate ecosystems represent a potential hostile environment for tropical species. Familiar prey and habitats are absent there, novel predators and competitors are present, and survival and physiological performance is reduced by exposure to cold winter temperatures. Thus, tropical fishes have to adapt to these novel conditions to thrive.
Continue reading ‘Warm and bubbly: increasing ocean CO2 and temperature affect fish distribution’Could seaweed be a salve to debate over salmon farming?
Published 26 February 2021 Media coverage Closed
For well over a decade, scientists on Canada’s coasts have demonstrated how growing seaweed or shellfish alongside salmon farms can provide a host of benefits — economic and ecological.
Researcher Thierry Chopin has been pitching the idea of co-cultivating multiple species together, or Integrated Multi-Trophic Aquaculture (IMTA), since the late 1990s.
The notion behind co-cultivation, or IMTA, is that extractive species like seaweed, mussels, or sea cucumbers can filter or flourish from the uneaten feed, waste, and byproducts from fish farms.
Continue reading ‘Could seaweed be a salve to debate over salmon farming?’Job opportunity: post-doc at NOAA-NMFS Alaska Fisheries Science Center
Published 26 February 2021 Jobs ClosedOcean acidification is occurring throughout the world’s oceans due to the release of terrestrially sequestered CO2 into the atmosphere and the subsequent diffusion of that anthropogenically released CO2 into the ocean.
There is a significant concern that ocean acidification could disrupt the productivity of fishery species. This pattern of ocean acidification (OA) is co-occurring with long-term increases in the temperatures of the world’s oceans that have already been shown to impact distribution and abundance of marine organisms. High latitude seas are predicted to be most affected by the combination of rising temperatures and OA. Previous work on OA interactions with other environmental factors in Alaska groundfish has focused on the potential for OA-induced changes to prey production to exacerbate the direct physiological effects of OA on early life stages. There has yet been little research examining the interaction between OA and elevated temperatures on fish productivity. To address this understanding gap, we will examine the interactive effects of OA and elevated temperatures on three fish species that are critical to Alaska and Arctic fisheries and foodwebs: Pacific cod which supports a major regional fishery and has previously been shown to be sensitive to OA; yellowfin sole which supports the world’s largest flatfish fishery; and Arctic cod which is a keystone species throughout Arctic ecosystems.
The incumbent will work as part of a research team examining the interactive effects of temperature and CO2 on the early life stages of Alaska fishery species and will be responsible for conducting laboratory experiments, biological measurements, statistical analyses, and production of peer-reviewed manuscripts. Experiments will examine the growth and survival responses, with the incumbent expanding the scope of research with additional response metrics and experimentation based on individual interest, experience, and expertise. Candidates with experience in the experimental culture of marine organisms will be strongly encouraged to apply. Anticipated start date December 2021.
Continue reading ‘Job opportunity: post-doc at NOAA-NMFS Alaska Fisheries Science Center’Physiological responses of Skeletonema costatum to the interactions of seawater acidification and the combination of photoperiod and temperature (update)
Published 25 February 2021 Science ClosedTags: biological response, growth, laboratory, light, multiple factors, photosynthesis, physiology, phytoplankton, temperature
Ocean acidification (OA), which is a major environmental change caused by increasing atmospheric CO2, has considerable influences on marine phytoplankton. But few studies have investigated interactions of OA and seasonal changes in temperature and photoperiod on marine diatoms. In the present study, a marine diatom Skeletonema costatum was cultured under two different CO2 levels (LC, 400 µatm; HC, 1000 µatm) and three different combinations of temperature and photoperiod length (8:16 L:D with 5 ∘C, 12:12 L:D with 15 ∘C, 16:8 L:D with 25 ∘C), simulating different seasons in typical temperate oceans, to investigate the combined effects of these factors. The results showed that specific growth rate of S. costatum increased with increasing temperature and day length. However, OA showed contrasting effects on growth and photosynthesis under different combinations of temperature and day length: while positive effects of OA were observed under spring and autumn conditions, it significantly decreased growth (11 %) and photosynthesis (21 %) in winter. In addition, OA alleviated the negative effect of low temperature and short day length on the abundance of RbcL and key photosystem II (PSII) proteins (D1 and D2). These data indicated that future ocean acidification may show differential effects on diatoms in different clusters of other factors.
Continue reading ‘Physiological responses of Skeletonema costatum to the interactions of seawater acidification and the combination of photoperiod and temperature (update)’Guest post: The threat of high-probability ocean ‘tipping points’
Published 25 February 2021 Science , Web sites and blogs ClosedClimate change is profoundly altering our oceans and marine ecosystems. Some of these changes are happening quickly and are potentially irreversible. Many are taking place silently and unnoticed.
In recent years, tipping points – thresholds where a small change could push a system into a completely new state – have increasingly become a focus for the climate research community.
However, these are typically thought of in terms of unlikely changes with huge global ramifications – often referred to as “low probability, high impact” events. Examples include the slowdown of the Atlantic Meridional Overturning Circulation and the rapid disintegration of the West Antarctic ice sheet.
In a new paper, published in the Proceedings of the National Academy of Sciences, my co-authors and I instead focus on the potential for what we call “high probability, high impact” tipping points caused by the cumulative impact of warming, acidification and deoxygenation.
We present the challenge of dealing with these imminent and long-lasting changes in the Earth system, and discuss options for mitigation and management measures to avoid crossing these tipping points.
Continue reading ‘Guest post: The threat of high-probability ocean ‘tipping points’’The quiet crossing of ocean tipping points
Published 25 February 2021 Science ClosedTags: chemistry, review
Anthropogenic climate change profoundly alters the ocean’s environmental conditions, which, in turn, impact marine ecosystems. Some of these changes are happening fast and may be difficult to reverse. The identification and monitoring of such changes, which also includes tipping points, is an ongoing and emerging research effort. Prevention of negative impacts requires mitigation efforts based on feasible research-based pathways. Climate-induced tipping points are traditionally associated with singular catastrophic events (relative to natural variations) of dramatic negative impact. High-probability high-impact ocean tipping points due to warming, ocean acidification, and deoxygenation may be more fragmented both regionally and in time but add up to global dimensions. These tipping points in combination with gradual changes need to be addressed as seriously as singular catastrophic events in order to prevent the cumulative and often compounding negative societal and Earth system impacts.
Continue reading ‘The quiet crossing of ocean tipping points’CO2-in-seawater reference materials: yesterday, today, and tomorrow – Andrew Dickson March 16 webinar
Published 24 February 2021 Events ClosedThe U.S. Interagency Working Group on Ocean Acidification presents:
CO2-in-seawater reference materials: yesterday, today, and tomorrow webinar
Professor Andrew Dickson (Scripps Institution of Oceanography, UC San Diego)
March 16, 2021, 9am Pacific (UTC -7:00)/ 12pm EST
We welcome all who work on ocean acidification and ocean carbonate chemistry studies to attend. This is the first community engagement in a larger effort to increase the resilience of the production and distribution of ocean carbonate chemistry reference materials.
Abstract: In 1989, the US National Science Foundation awarded a grant to the Scripps Institution of Oceanography in preparation for the upcoming US JGOFS program. This grant was intended to enable the preparation of standards for the measurement of the CO2 properties of seawater that could be distributed to laboratories participating in the program so as to assure the production of a coherent data set from the differing labs and methodologies likely to be involved in the program. The model for this activity was the production and distribution of IAPSO Standard Seawater. This initial program was expanded through additional support from the US Department of Energy to enable international distribution to laboratories making CO2 measurement as part of the extensive joint ocean survey supported by JGOFS and the WOCE Hydrographic Program.
Continue reading ‘CO2-in-seawater reference materials: yesterday, today, and tomorrow – Andrew Dickson March 16 webinar’
ORONO — A team of researchers from the University of Maine’s Darling Marine Center in Walpole and Bigelow Laboratory for Ocean Sciences in East Boothbay and the Maine Department of Marine Resources in West Boothbay Harbor recently published their research on the effects of ocean warming and acidification on gene expression in the earliest life stages of the American lobster.
The work was published in the scientific journal Ecology and Evolution with collaborators from the University of Prince Edward Island and Dalhousie University in Canada.
The team’s experiments examined the gene regulatory response of post-larval lobsters to the separate and combined effects of warming and acidification anticipated by the end of the 21st century. They found that genes regulating a range of physiological functions, from those controlling shell formation to the immune response, are either up- or down-regulated. Importantly, they observed that the two stressors combined induced a greater gene regulatory response than either stressor alone.
The results from the study indicate that changes in gene expression of post-larval lobster may act as a mechanism to accommodate rapid changes in the ocean environment. Team leader Maura Niemisto noted that “there is still need for further study to determine how rapidly populations of the species may be able to adapt to changing conditions. To better understand how gene regulation in response to environmental changes functions within the species, we should look at subpopulations and multigenerational studies to determine the extent of species’ capacity to respond to altered environmental conditions.”
Continue reading ‘Lobster research explores ocean warming effects’Springtime spatial distributions of biogenic sulfur compounds in the Yangtze river estuary and their responses to seawater acidification and dust
Published 24 February 2021 Science ClosedTags: biological response, laboratory, multiple factors, North Pacific, nutrients, physiology, phytoplankton
The spatial distributions of dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP), and dimethylsulfoxide (DMSO) were investigated in the Yangtze River Estuary from 9 to 23 March, 2018. The average concentrations of DMS, dissolved DMSP (DMSPd), particulate DMSP (DMSPp), dissolved DMSO (DMSOd) and particulate DMSO (DMSOp) were 3.00 ± 2.53, 1.75 ± 1.08, 10.89 ± 14.28, 9.80 ± 7.79, and 9.51 ± 8.90 nmol L‐1, respectively. The high DMS and DMSP concentrations occurred mainly in the open sea, exhibiting distribution patterns similar to chlorophyll a (Chl‐a). Due to the release of resuspended sediments, elevated DMSO concentrations were observed in the bottom waters of some stations. The three sulfur compounds were positively correlated with Chl‐a (p < 0.05), suggesting that phytoplankton played an essential role in the production of sulfur compounds. Comparisons with previous research showed that the concentrations of DMS, DMSP, and DMSOp exhibited clear seasonal variability. The average sea‐to‐air flux of DMS was 8.19 ± 12.94 μmol m‐2 d‐1 in the study area, indicating that the estuary and continental shelf sea were significant contributors to the global sulfur cycle. Ship‐based incubation experiments showed that lower pH inhibited the production of the three biogenic sulfur compounds, while the addition of dust promoted their release. Therefore, in the future, the inhibitory effect of seawater acidification on the production of phytoplankton and sulfur compounds might be offset, to some degree, by the input of nutrient‐rich dust.
Continue reading ‘Springtime spatial distributions of biogenic sulfur compounds in the Yangtze river estuary and their responses to seawater acidification and dust’Upcoming webinar: Canada’s ocean acidification community of practice
Published 24 February 2021 Events Closed
Join us for the second CoP webinar of the year, and get to know Canada’s Ocean Acidification Community of Practice—Wednesday, March 10 at 1pm AST/12pm EST / 9am PST.
The MEOPAR OA Community of Practice (CoP) was formed in 2018, with the overarching goal of sharing knowledge and improving linkages between OA knowledge creators and end-users across Canada. The OA CoP is led by two co-leads, Dr. Helen Gurney-Smith (DFO) and Dr. Brent Else (University of Calgary) and coordinator, Dr. Kristina Barclay (University of Calgary, MEOPAR), with guidance from an interdisciplinary Steering Committee from across the country. OA CoP objectives include the development of knowledge transfer and community engagement via accessible content, resources, and databases, and best-practices for data collection and sharing involving research groups, stakeholders, and community-based research.
In this webinar, the OA CoP will present some of its key activities to date, its new online resources and blog series, as well as updates on the development of future projects. Current and future activities are focused on increasing online content and resources to increase OA CoP awareness and engagement, the development of a low-cost OA sensor package to aid aquaculture operations and larger monitoring efforts, conducting regional vulnerability assessments, and participation in partner OA organizations, including the GOA-ON North American Hub, the OA Information Exchange, DFO-NOAA OA Working Groups, the OA Alliance, and MEOPAR.
Continue reading ‘Upcoming webinar: Canada’s ocean acidification community of practice’Influence of acidification and warming of seawater on biofouling by bacteria grown over API 5L steel
Published 24 February 2021 Science ClosedTags: abundance, biological response, BRcommunity, community composition, laboratory, mesocosms, molecular biology, multiple factors, otherprocess, prokaryotes, protists, South Atlantic, temperature
The acidification and warming of seawater have several impacts on marine organisms, including over microorganisms. The influence of acidification and warming of seawater on biofilms grown on API 5L steel surfaces was evaluated by sequencing the 16S ribosomal gene. For this, three microcosms were designed, the first simulating the natural marine environment (MCC), the second with a decrease in pH from 8.1 to 7.9, and an increase in temperature by 2 °C (MMS), and the third with pH in around 7.7 and an increase in temperature of 4 °C (MES). The results showed that MCC was dominated by the Gammaproteobacteria class, mainly members of the Alteromonadales Order. The second most abundant group was Alphaproteobacteria, with a predominance of Rhodobacterales and Oceanospirillales. In the MMS system there was a balance between representatives of the Gammaproteobacteria and Alphaproteobacteria classes. In MES there was an inversion in the representations of the most prevalent classes previously described in MCC. In this condition, there was a predominance of members of the Alphaproteobacteria Class, in contrast to the decrease in the abundance of Gammaproteobacteria members. These results suggest that possible future climate changes may influence the dynamics of the biofouling process in surface metals.
Continue reading ‘Influence of acidification and warming of seawater on biofouling by bacteria grown over API 5L steel’Evaluation of actin as a reference for quantitative gene expression studies in Emiliania huxleyi (Prymnesiophyceae) under ocean acidification conditions
Published 24 February 2021 Science ClosedTags: biological response, laboratory, methods, molecular biology, physiology, phytoplankton
Gene expression studies of marine phytoplankton under ocean acidification conditions are frequently based on relative measurements, with actin commonly used as a reference gene. Evidence from other organisms suggests that actin gene expression may be regulated by environmental conditions, compromising the role of actin as a reference gene. In this work the reliability of actin as a reference gene for ocean acidification experimental conditions (high CO2 vs low CO2) in two different metabolic states (acclimated metabolism vs perturbed metabolism) for the coccolithophore Emiliania huxleyi was tested. The transcriptional response of the actin (act) is compared with the expression of specific target genes associated with inorganic carbon uptake (α-carbonic anhydrase: αca1) and assimilation (RuBisCO: rbcL), which was regulated under the experimental conditions. Our results showed act expression instability in experimental conditions, evidencing that act is not a reliable reference gene for studies assessing the effect of ocean acidification on Emiliania huxleyi. Furthermore, when the act-based normalization was quantitatively tested, rbcL and αca1 expression were compromised, leading us to conclude that absolute gene expression quantification should be considered as a potentially reliable alternative for studying gene expression under ocean acidification conditions
Continue reading ‘Evaluation of actin as a reference for quantitative gene expression studies in Emiliania huxleyi (Prymnesiophyceae) under ocean acidification conditions’The next decade of Alaskan ocean acidification research (text & video)
Published 24 February 2021 Web sites and blogs ClosedWebinar page: uaf-accap.org/event/oa-next10years/
February 16, 2021 @ 10:00 am to 11:00 am AKST
Speaker: Jessica Cross, Oceanographer, NOAA Pacific Marine Environmental Laboratory
Over the last decade, ocean acidification (OA) has emerged as one of the most prominent issues in Alaskan marine research, and a possible threat to culturally and commercially important marine resources. Multiple communities around the state are now engaged in their own OA studies and monitoring, and are asking a common question: what risks does my region face? These are especially salient questions for Alaskans, given that the intensity, duration and extent of OA events have been greater than other ocean basins. Given the pace of the observed changes due to OA around Alaska, the area is commonly referred to as a bellwether and the proverbial “canary in the coal mine” for the rest of the global ocean. Here, we will take a look back at the last ten years of OA research in the Bering Sea, and highlight new, cutting-edge biogeochemical modeling, forecasting, and projection efforts that have dramatically increased our capacity to understand Alaskan OA from a large-scale perspective just in the past year. For example, we have scaled point observations to the entire Bering Sea shelf to show that corrosive conditions have covered almost 60% of critical habitat areas in the last ten years, and forecasts indicate that 2020 was even more strongly corrosive compared to the 2003-2019 average. These new insights have been quickly picked up by our colleagues engaged in ongoing laboratory studies of species-specific OA vulnerability and larger-scale ecosystem and bioeconomic analyses of OA impact. Our goal is to continue refining our capacity to identify new risks and emerging resilience of Alaskan ecosystems, and guide sound, evidence-based decisions that support sustainable marine resources in the future.
Continue reading ‘The next decade of Alaskan ocean acidification research (text & video)’In the Aleutians, climate change and ocean acidification impacts add to legacies of past exploitation
Published 24 February 2021 Web sites and blogs ClosedCenturies of human impacts could make it harder for Southern Bering Sea ecosystems to adapt to climate change
The Bering Sea region, the Pacific gateway to the Arctic Ocean, is home to ecosystems on land and in the ocean that are both abundant and fragile. It’s also changing very quickly — and those changes offer a preview of the changes in store for other parts of the Arctic. This story is part of an ArcticToday series on the changing Bering Sea — and what those transformations mean for fish, wildlife and people.
In the waters around the Aleutian Islands, the 1,200-mile chain that arcs across the southern edge of the Bering Sea from Alaska to Kamchatka, modern climate change has layered atop a centuries-old legacy of human assaults to send combined impacts cascading through the marine ecosystem.
Continue reading ‘In the Aleutians, climate change and ocean acidification impacts add to legacies of past exploitation’Evolution of paleo-climate and seawater pH from the late Permian to postindustrial periods recorded by boron isotopes and B/Ca in biogenic carbonates
Published 22 February 2021 Science ClosedTags: chemistry, paleo
Highlights
• The fundamentals and advances in δ11B-pH and B/Ca proxies have been demonstrated.
• The evolution of atmospheric CO2 over million-year scale and millennium scale is reviewed.
• The significant ocean acidifications and the associated driving forces were clarified.
Abstracts
Cycling of CO2 between the oceans and the atmosphere has significant impacts on the global climate change. The accurate reconstructions of paleo-pH and atmospheric-oceanic carbon cycling using geochemical tracers (e.g., δ11B, B/Ca) in marine carbonates are reviewed in this work, including the fundamental mechanisms and the remaining challenges in these proxies and the progresses in understanding of evolution of paleo-climate and seawater pH from the late Permian to postindustrial periods. The proxies provide new insight into the evolution of atmospheric CO2 concentrations at time scales from tens of millions to thousands of years, and the direct evidence to the significant ocean acidification during the mass extinction events, and the CO2 cycling in ocean-atmosphere system during the Last Deglaciation and post-industrial periods. On the basis of extensive investigation, it could be concluded that: (i) the carbon dioxide levels and their impacts on Earth surface temperature during the Cenozoic cooling, the Pliocene warmth, and the mid-Pleistocene transition have been evaluated by the combination of multiple proxies; (ii) the benthic/planktonic foraminiferal B/Ca and δ11B data provided consistent implications for global climate variations during the Late Pleistocene, the Late Glacial, Last Glacial Maximum, and the Younger Dryas event; (iii) perturbations of surface ocean pH at the Permo-Triassic (P-T) boundary, the Pliensbachian-Toarcian (Pl-To) boundary, the Cretaceous-Paleogene (K/Pg) boundary and the Palaeocene-Eocene Thermal Maximum (PETM) global warming event were triggered by the large injection of carbon, the short episodic pulses of volcanogenic CO2, the Chicxulub impact, and the volcanism activities of the North Atlantic Igneous Province, respectively; (iv) the ocean acidification in the equatorial and polar Pacific during the Last Deglaciation implied an expanded zone of equatorial upwelling and resultant CO2 emission from higher subsurface dissolved inorganic carbon concentration. The acceleration of modern acidification in post-industrial time was not only driven by anthropogenic CO2 but also varied synchronously with inter-decadal changes in Asian Winter Monsoon Intensity.
Continue reading ‘Evolution of paleo-climate and seawater pH from the late Permian to postindustrial periods recorded by boron isotopes and B/Ca in biogenic carbonates’
