Impacts of ocean acidification (OA) on noncalcifying organisms and the possibly responsible mechanism have aroused great research interests with the intensification of global warming. The present study focused on a noxious, noncalcifying, bloom-forming dinoflagellate, Karenia mikimotoi (K. mikimotoi), and its variation of growth patterns exposed to different periods of seawater acidification with stressing gradients was discussed. The dinoflagellates under short-time acidifying stress (2d) with different levels of CO2 presented significant growth inhibition (p < 0.05). The cell cycle was obviously inhibited at S phase, and the photosynthetic carbon fixation was also greatly suppressed (p < 0.05). Apoptosis was observed and the apoptotic rate increased with the increment of pCO2. Similar tendencies were observed in the key components of mitochondrial apoptotic pathway (the mitochondrial membrane potential (MMP), Caspase-3 and -9, and Bax/Bcl-2 ratio). However, under prolonged stressing time (8 d and 15 d), the growth of dinoflagellates was recovered or even stimulated, the photosynthetic carbon fixation was significantly increased (p < 0.05), the cell cycle of division presented little difference with those in the control, and no apoptosis was observed (p > 0.05). Besides, acidification adjusted by HCl addition and CO2 enrichment resulted in different growth performances, while the latter had a more negative impact. The results of present study indicated that (1) the short-time exposure to acidified seawater led to reduced growth performance via inducing apoptosis, blocking of cell cycle, and the alteration in photosynthetic carbon fixation. (2) K. mikimotoi had undergone adaptive changes under long-term exposure to CO2 induced seawater acidification. This further demonstrated that K. mikimotoi has strong adaptability in the face of seawater acidification, and this may be one of the reasons for the frequent outbreak of red tide. (3) Ions that dissociated by the dissolved CO2, instead of H+ itself, were more important for the impacts induced by the acidification. This work thus provides a new perspective and a possible explanation for the dominance of K. mikimotoi during the occurrence of HABs.
Continue reading ‘The bloom-forming dinoflagellate Karenia mikimotoi adopts different growth modes when exposed to short or long period of seawater acidification’Archive Page 217
The bloom-forming dinoflagellate Karenia mikimotoi adopts different growth modes when exposed to short or long period of seawater acidification
Published 9 September 2021 Science ClosedTags: biological response, laboratory, molecular biology, morphology, North Pacific, photosynthesis, physiology, phytoplankton
Individual and interactive effects of ocean warming and acidification on adult Favites colemani
Published 9 September 2021 Science ClosedTags: adaptation, biological response, corals, growth, laboratory, molecular biology, mortality, multiple factors, North Pacific, otherprocess, photosynthesis, physiology, temperature
Tropical coral reefs are threatened by local-scale stressors that are exacerbated by global ocean warming and acidification from the post-industrial increase of atmospheric CO2 levels. Despite their observed decline in the past four decades, little is known on how Philippine coral reefs will respond to ocean warming and acidification. This study explored individual and synergistic effects of present-day (pH 8.0, 28°C) and near-future (pH 7.7, 32°C) scenarios of ocean temperature and pH on the adult Favites colemani, a common massive reef-building coral in Bolinao-Anda, Philippines. Changes in seawater temperature drive the physiological responses of F. colemani, whereas changes in pH create an additive effect on survival, growth, and photosynthetic efficiency. Under near-future scenarios, F. colemani showed sustained photosynthetic competency despite the decline in growth rate and zooxanthellae density. F. colemani exhibited specificity with the Cladocopium clade C3u. This coral experienced lower growth rates but survived projected near-future ocean warming and acidification scenarios. Its pH-thermal stress threshold is possibly a consequence of acclimation and adaptation to local environmental conditions and past bleaching events. This research highlights the importance of examining the susceptibility and resilience of Philippine corals to climate-driven stressors for future conservation and restoration efforts in the changing ocean.
Continue reading ‘Individual and interactive effects of ocean warming and acidification on adult Favites colemani’Hydrogeochemistry and acidic property of submarine groundwater discharge around two coral islands in the Northern South China Sea
Published 9 September 2021 Science ClosedTags: biogeochemistry, biological response, chemistry, echinoderms, field, laboratory, mollusks, North Pacific, physiology
Submarine groundwater discharge (SGD) is an important source of nutrients in many coastal regions, yet little information is available on its carbonate chemistry and controlling factors. This study examined the processes and factors controlling the hydrogeochemistry and acidic property of the groundwaters and SGD waters of two isolated coral islands, Liuqiu Island (13 km off southwestern Taiwan) and Dongsha Island (located in the northern South China Sea, 420 km away from Liuqiu Island). Our results showed that the total alkalinity and dissolved inorganic carbon (DIC) of the fresh SGD waters were controlled mainly by the chemical weathering of carbonate minerals. Part of the DIC came from the organic matter decomposition or soil CO2, reducing the pH and CO32− concentration. Distributions of the carbonate chemistry and nutrients of the SGD waters were controlled mainly by physical mixing between the groundwater and the ambient seawater under the seabed, the so-called subterranean estuary. The Ca2+ released through weathering significantly increased the saturation state of aragonite or calcite, reducing the corrosiveness of the SGD waters on the carbonate rocks. This study is likely the first to examine the effects of the acidic property of SGD waters on the biogenic carbonate spine of a sea urchin and a pteropod shell. The spring water with similar carbonate chemistry to that of the freshwater SGD endmember from Liuqiu Island with a saturation state of aragonite of 0.96 caused observable dissolution on the spine of a sea urchin and a pteropod shell, but the spine dissolved more readily. This was because the spine is made of high-Mg calcite, which has higher solubility than that of aragonite or calcite. Such a result implies that some marine organisms with carbonate skeletons or shells containing high Mg:Ca ratios may suffer the impact of ocean acidification earlier. Although the SGD may contribute less than 10% of freshwater discharge by rivers to the coastal area, its impact on coastal biogeochemical cycles and ecosystems due to its acidic property and continual effect on the coast all year round deserves further investigation.
Continue reading ‘Hydrogeochemistry and acidic property of submarine groundwater discharge around two coral islands in the Northern South China Sea’Coralporosis: ocean acidification leaves deep-sea coral reefs at risk of collapse
Published 9 September 2021 Science ClosedTags: corals, review
As we age, our skeletons often become riddled with osteoporosis, a disease in which the body loses too much bone. As a result, our hips and wrists become weak and may break. Could the same thing happen to the skeletons of coral reefs? Recent research says yes, and points to a weakening of deep-sea corals’ “bones” from ocean acidification.
The study, which advances efforts to understand how reefs of the future will look and what we can do to preserve them and the life they support, was published in Frontiers of Marine Science in September 2020. It was led by University of Edinburgh scientists, along with researchers from Heriot-Watt University and the US National Oceanic and Atmospheric Administration (NOAA) and was supported by the European Union’s Horizon 2020 Research and Innovation Programme and several other funders.
“Ocean acidification is a threat to the net growth of tropical and deep-sea coral reefs due to gradual changes in the balance between reef growth and loss processes,” write lead author Sebastian Hennige of the University of Edinburgh’s School of GeoSciences and his coauthors. “We go beyond identification of coral dissolution induced by ocean acidification to identify a mechanism that will lead to the loss of habitat in cold-water coral reef habitats on an ecosystem scale.”
What is ocean acidification? Find out how research at Plymouth is tackling this global carbon dioxide problem (text & video)
Published 9 September 2021 Educational Materials , Organizations , Web sites and blogs ClosedTags: resource, video, webpage, website
Explore the science behind falling ocean pH and the impact this has on marine ecosystem balance
Ocean acidification occurs when carbon dioxide (CO2) is absorbed rapidly into the ocean.
It reacts with water molecules (H2O) to form carbonic acid (H2CO3). This compound then breaks down into a hydrogen ion (H+) and bicarbonate (HCO3–). These hydrogen ions decrease seawater pH.
In chemical terms, ocean acidfication is described like this:
CO2 + H2O → (H+) + (HCO3–)
The rising CO2 problem
Since the beginning of the Industrial Revolution in the early 1800s, the rise of fossil fuel-powered machinery has been the catalyst for the emission of billions of tonnes of carbon dioxide (CO2) and other greenhouse gases into our atmosphere.
Carbon dioxide levels have now risen by 30 per cent since the Industrial Revolution.
Scientists now know that about a quarter of carbon dioxide emissions have been absorbed by the oceans.
Monitoring shows that burning fossil fuels has caused unprecedented changes to ocean chemistry due to ocean uptake of millions of tonnes of CO2 each year.
Falling pH
Surface ocean waters are alkaline; on average pH 8.1. But because a quarter of human CO2 emissions are taken up by surface seawater this could drop to pH 7.8 by the end of the century, lower than at any time in human history.
The change in ocean acidity will not make it more dangerous for us to swim or surf in.
Seas are not actually going to be acidic – they will still be more alkaline than tap water.
Ocean acidification is happening rapidly worldwide. We have shown that this has knock-on effects that degrade marine ecosystems and impact fishing industries and food supplies. Plans are in place to ensure that University of Plymouth research is strategically aligned to inform the United Nations Decade of Ocean Science for Sustainable Development (2021-2030) and embed solutions that slow ocean degradation and build recovery of our coastal resources.
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Continue reading ‘What is ocean acidification? Find out how research at Plymouth is tackling this global carbon dioxide problem (text & video)’Ocean acidification a poem by Samantha Jones
Published 9 September 2021 Art , Presentations ClosedTags: resource, video/audio
The poem “Ocean Acidification” blends science and poetry to explore one of the challenges a high-CO2 world poses to the ocean and the species, ecosystems, and human communities that depend on it.
Author Samantha Jones’ PhD research on carbon cycling in the Canadian Arctic inspired this work, which first appeared in WATCH YOUR HEAD (online) in March 2021 at watchyourhead.ca/.
Samantha is currently a PhD Candidate in Geography at the University of Calgary in Alberta, Canada.
Continue reading ‘Ocean acidification a poem by Samantha Jones’Evolution and biomineralization of pteropod shells
Published 8 September 2021 Science ClosedTags: mollusks, review, zooplankton
Highlights
- Pteropod shells harbor a striking diversity of microstructures.
- Curved aragonite fibres are found in both superfamilies: Limacinoidea (coiled) and Cavolinioidea (uncoiled).
- Different levels of complexity of the helical microstructure exist: from incomplete to multiple helical turns.
- Microstructural observations in the fossil record suggest that the emergence of curved fibres precedes the diversification of euthecosomatous pteropods.
- Candidate biomineralization genes are identified based on shell matrix proteins from benthic and terrestrial snails.
Abstract
Shelled pteropods, known as ‘sea butterflies’, are a group of small gastropods that spend their entire lives swimming and drifting in the open ocean. They build thin shells of aragonite, a metastable polymorph of calcium carbonate. Pteropod shells have been shown to experience dissolution and reduced thickness with a decrease in pH and therefore represent valuable bioindicators to monitor the impacts of ocean acidification. Over the past decades, several studies have highlighted the striking diversity of shell microstructures in pteropods, with exceptional mechanical properties, but their evolution and future in acidified waters remains uncertain. Here, we revisit the body-of-work on pteropod biomineralization, focusing on shell microstructures and their evolution. The evolutionary history of pteropods was recently resolved, and thus it is timely to examine their shell microstructures in such context. We analyse new images of shells from fossils and recent species providing a comprehensive overview of their structural diversity. Pteropod shells are made of the crossed lamellar and prismatic microstructures common in molluscs, but also of curved nanofibers which are proposed to form a helical three-dimensional structure. Our analyses suggest that the curved fibres emerged before the split between coiled and uncoiled pteropods and that they form incomplete to multiple helical turns. The curved fibres are seen as an important trait in the adaptation to a planktonic lifestyle, giving maximum strength and flexibility to the pteropod thin and lightweight shells. Finally, we also elucidate on the candidate biomineralization genes underpinning the shell diversity in these important indicators of ocean health.
Continue reading ‘Evolution and biomineralization of pteropod shells’Reduced H+ channel activity disrupts pH homeostasis and calcification in coccolithophores at low ocean pH
Published 8 September 2021 Science ClosedTags: biological response, laboratory, light, molecular biology, morphology, multiple factors, physiology, prokaryotes
Coccolithophores produce the bulk of ocean biogenic calcium carbonate but this process is predicted to be negatively affected by future ocean acidification scenarios. Since coccolithophores calcify intracellularly, the mechanisms through which changes in seawater carbonate chemistry affect calcification remain unclear. Here we show that voltage-gated H+ channels in the plasma membrane of Coccolithus braarudii serve to regulate pH and maintain calcification under normal conditions, but have greatly reduced activity in cells acclimated to low pH. This disrupts intracellular pH homeostasis and impairs the ability of C. braarudii to remove H+ generated by the calcification process, leading to specific coccolith malformations. These coccolith malformations can be reproduced by pharmacological inhibition of H+ channels. Heavily-calcified coccolithophore species such as C. braarudii, which make the major contribution to carbonate export to the deep ocean, have a large intracellular H+ load and are likely to be most vulnerable to future decreases in ocean pH.
Continue reading ‘Reduced H+ channel activity disrupts pH homeostasis and calcification in coccolithophores at low ocean pH’Effects of climate change on metabolite accumulation in freshwater and marine cyanobacteria
Published 8 September 2021 Science ClosedTags: biological response, laboratory, light, multiple factors, physiology, prokaryotes
Highlights
- Toxin profiles of marine and freshwater cyanobacteria.
- Metabolomics of two microcystin producers using orbitrap mass spectrometry.
- Different responses of cyanobacteria to CO2 induced pH level changes.
- Semi-continuous culturing and CO2 micro-adjustment.
Abstract
Global climate change and anthropogenic nutrient inputs are responsible for increased frequency of cyanobacterial blooms that potentially contain 55 classes of bioactive metabolites. This study investigated the effects of CO2 availability and concomittant pH levels on two cyanobacteria that produce microcystins: a marine cf. Synechocystis sp. and a freshwater Microcystis aeruginosa. Cyanobacterial strains were semi-continuously cultured in mesotrophic growth media at pH 7.5, 7.8, 8.2, and 8.5 via a combination of CO2 addition and control of alkalinity. The cell concentration between treatments was not significantly different and nutrient availability was not limited. Concentration of most known cyanobacterial bioactive metabolites in both cyanobacterial strains increased as CO2 increased. At pH 7.8, bioactive metabolite intracellular concentration in M. aeruginosa and Synechocystis was 1.5 and 1.2 times greater than the other three treatments, respectively. Intracellular concentration of microginin in M. aeruginosa at pH 7.5 was reduced by 90% compared to the other three treatments. Intracellular concentration of microcyclamide-bistratamide B was lower in M. aeruginosa and higher in Synechocystis at elevated CO2 concentration. M. aeruginosa products were more diverse metabolites than Synechocystis. The diversity of accumulated metabolites in M. aeruginosa increased as CO2 increased, whereas the metabolite diversity in Synechocystis decreased as pH decreased. Overall, intracellular concentration of bioactive metabolites was higher at greater CO2 concentrations; marine and freshwater cyanobacteria had different allocation products when exposed to differing CO2 environments.
Continue reading ‘Effects of climate change on metabolite accumulation in freshwater and marine cyanobacteria’Reconstruction of global surface ocean pCO2 using region-specific predicators based on a stepwise FFNN regression algorithm
Published 8 September 2021 Science ClosedTags: chemistry, globalmodeling, methods, modeling
Various machine learning methods were attempted in the global mapping of surface ocean partial pressure of CO2 (pCO2) to reduce the uncertainty of global ocean CO2 sink estimate due to undersampling of pCO2. In previous researches the predicators of pCO2 were usually selected empirically based on theoretic drivers of surface ocean pCO2 and same combination of predictors were applied in all areas unless lack of coverage. However, the differences between the drivers of surface ocean pCO2 in different regions were not considered. In this work, we combined the stepwise regression algorithm and a Feed Forward Neural Network (FFNN) to selected predicators of pCO2 based on mean absolute error in each of the 11 biogeochemical provinces defined by Self-Organizing Map (SOM) method. Based on the predicators selected, a monthly global 1° × 1° surface ocean pCO2 product from January 1992 to August 2019 was constructed. Validation of different combination of predicators based on the SOCAT dataset version 2020 and independent observations from time series stations was carried out. The prediction of pCO2 based on region-specific predicators selected by the stepwise FFNN algorithm were more precise than that based on predicators from previous researches. Appling of a FFNN size improving algorithm in each province decreased the mean absolute error (MAE) of global estimate to 11.32 μatm and the root mean square error (RMSE) to 17.99 μatm. The script file of the stepwise FFNN algorithm and pCO2 product are distributed through the Institute of Oceanology of the Chinese Academy of Sciences Marine Science Data Center (IOCAS; http://dx.doi.org/10.12157/iocas.2021.0022, Zhong et al., 2021).
Continue reading ‘Reconstruction of global surface ocean pCO2 using region-specific predicators based on a stepwise FFNN regression algorithm’ICES Annual Science Conference (ASC) 2021 : taking stock on ocean acidification research for provision of future efforts
Published 8 September 2021 Events ClosedDate: 6 – 10 September 2021
Location: virtual conference
Because of the COVID-19 pandemic, ASC 2021 is organized as a virtual conference.
The conference consists of live interactive sessions and pre-recorded presentations.
Live sessions run 15:00–20:00 CEST Monday to Thursday and 15:00–18:00 CEST on Friday. All pre-recorded presentations are available for on demand viewing between 23 August–30 September via the conference app.
All registered participants are also invited to join our first ever Early Career Scientist day, taking place on Thursday, 2 September.
Join us for the first ever virtual #ICESASC21!
Register today and donwload the conference app!
Date: 9 September 2021
Time: 16:00 – 17:00 CEST
Session K: Taking stock on ocean acidification research for provision of future efforts
Continue reading ‘ICES Annual Science Conference (ASC) 2021 : taking stock on ocean acidification research for provision of future efforts’Acute acidification stress weakens the head kidney immune function of juvenile Lates calcarifer
Published 7 September 2021 Science ClosedTags: adaptation, biological response, fish, laboratory, molecular biology, North Pacific, otherprocess, physiology
Highlights
- A comprehensive analysis of L. calcarifer head kidney acute acidification response.
- Acute adaptation strategies to different acidification levels were different.
- Acute acidification stress had the effect of weakening immune function.
Abstract
Acidized water environment can impact many physiological processes of aquatic animals. The response of the head kidney to acidification, especially the immune response, is of great significance to health. This study analyzed the histological and transcriptional changes under different acidification levels (C group, pH 8.1; P group, pH 7.4; E group, pH 3.5) in the short term (12 h, 36 h and 60 h) in the head kidney of juvenile L. calcarifer. The results showed that the acidification of the water environment caused tissue damage to the head kidney of L. calcarifer, and the damage appeared earlier and was stronger in the extreme pH group. The transcriptional response of L. calcarifer head kidney increased with the increase of acidification level. The two treatments transcriptional responses showed different trends in terms of time. After KEGG function enrichment, with the increase of stimulation time, the proportion of down-regulated pathways was increasing, and the types of pathway enrichment at different acidification levels were quite different at the initial stage. At 12 h, the first category in the P group with the most significant number of pathways was ‘Metabolism’, and the first category in the E group with the largest number of pathways was ‘Human Diseases’. At 60 h, the enrichment pathways of the two groups were highly overlapping in immune-related pathways, which contained 26 common DEGs. They had a dominant expression pattern. In the P group, the expression level decreased with time. In the E group, the down-regulation degree of expression level at 12 h reached the level of the P group at 60 h, and the expression level remained low until 60 h. Through the correlation network, interferon regulatory factor 7 (IRF7), Tripartite motif containing-21 (TRIM21), Signal transducer and activator of transcription 1 (STAT1) and Signal transducer and activator of transcription 3 (STAT3) were found to have the most correlation with other genes. In this study, juvenile L. calcarifer showed different coping strategies to different levels of acute acidification stress, but all of them resulted in the extensive weakening of head kidney immune function.
Continue reading ‘Acute acidification stress weakens the head kidney immune function of juvenile Lates calcarifer’Effect of pH and type of stirring on the spontaneous precipitation of CaCO3 at identical initial supersaturation, ionic strength and a(Ca2+)/a(CO32−) ratio
Published 7 September 2021 Science ClosedTags: calcification, chemistry
CaCO3 precipitation is physical-chemical basis of biomineral formation of hard tissue (shells, skeletons) in marine calcifying organisms (=biomineralization). Processes controlling biomineralization are still not fully clarified, so the study of influence of pH on basic processes of CaCO3 precipitation should contribute to better understanding of biomineralization under climate change. This paper reports on the effect of initial pH (pH0) and type of stirring (mechanical and magnetical) on spontaneous precipitation and phase composition, size and morphology of spontaneously precipitated CaCO3 formed at the identical initial supersaturation, ionic strength and a(Ca2+)/a(CO32−) ratio. The initial pH varied in a range 8.50 ≤ pH0 ≤ 10.50 and included values relevant for mimicking the conditions related to biomineralization in marine organisms. In all systems two CaCO3 polymorphs were found: calcite and/or vaterite. The increase of pH0 favoured the formation of rhombohedral calcite no matter the type of stirring. This was exclusively influenced by the systems’ pH0 (other relevant initial parameters were identical). Furthermore, increase of pH0 caused change of vaterite morphology from cauliflower-like spheroids to regular spherulites. The mechanically stirred systems produced larger calcite and vaterite particles and higher content of calcite.
Continue reading ‘Effect of pH and type of stirring on the spontaneous precipitation of CaCO3 at identical initial supersaturation, ionic strength and a(Ca2+)/a(CO32−) ratio’The role of a changing Arctic Ocean and climate for the biogeochemical cycling of dimethyl sulphide and carbon monoxide
Published 7 September 2021 Science ClosedTags: Arctic, community composition, otherprocess, phytoplankton, policy, prokaryotes, review, socio-economy
Dimethyl sulphide (DMS) and carbon monoxide (CO) are climate-relevant trace gases that play key roles in the radiative budget of the Arctic atmosphere. Under global warming, Arctic sea ice retreats at an unprecedented rate, altering light penetration and biological communities, and potentially affect DMS and CO cycling in the Arctic Ocean. This could have socio-economic implications in and beyond the Arctic region. However, little is known about CO production pathways and emissions in this region and the future development of DMS and CO cycling. Here we summarize the current understanding and assess potential future changes of DMS and CO cycling in relation to changes in sea ice coverage, light penetration, bacterial and microalgal communities, pH and physical properties. We suggest that production of DMS and CO might increase with ice melting, increasing light availability and shifting phytoplankton community. Among others, policy measures should facilitate large-scale process studies, coordinated long term observations and modelling efforts to improve our current understanding of the cycling and emissions of DMS and CO in the Arctic Ocean and of global consequences.
Continue reading ‘The role of a changing Arctic Ocean and climate for the biogeochemical cycling of dimethyl sulphide and carbon monoxide’Friday Earth Sciences Talk (FEST)
Date: 17 September 2021
Time: 16:00 – 17:00
Speaker: Prof. Dr Jack Middelburg
Title: Titrating system earth with carbon dioxide
Description:
Atmospheric carbon dioxide concentrations have varied over much of the geological history and are increasing at unprecedented in the Anthropocene. Uptake and storage of anthropogenic carbon dioxide in the ocean is related to the reaction of dissolved carbon dioxide with water to form bicarbonate (and minor quantities of carbonic acid and carbonate). Alkalinity, the excess of bases in solution, governs the efficiency at which this occurs and provides buffering capacity towards acidification.
Here I present the biogeochemical processes impacting the ocean carbonate system over multiple timescales. Over geological time scales alkalinity input to the ocean from weathering should be in balance with removal via carbonate mineral burial in the sea. However, a re-evaluation of the modern oceanic alkalinity balance revealed that the so far neglected riverine delivery of particulate inorganic carbon should be included to balance inputs and outputs.
Next I present a retrodiction of ocean alkalinity, dissolved inorganic carbon and pH over the last 50 million years. At intermediate time scales (decades to thousands of years), the marine carbon system is governed by carbonate compensation mechanisms, i.e. changes in calcium carbonate production and dissolution, and I argue that we need to distinguish between biological and chemical carbonate compensation. At the shortest time scale, ocean chemistry is buffered by proton transfer among various dissolved species. These processes are well understood and can be used to quantify the impact of individual biogeochemical processes on the pH of seawater.
Continue reading ‘FEST: titrating system earth with carbon dioxide’SEAS postdoctoral research fellow in marine biogeochemical hazards
Published 7 September 2021 Jobs ClosedDeadline: 31 October 2021
Thematic area and supervisor
This SEAS postdoctoral research fellow position is connected to the thematic area of marine biogeochemical hazards under warming, ocean acidification, and deoxygenation.
The position is open to an incoming candidate, see mobility rules.
The successful candidate will be employed at the Geophysical Institute and included in the research group on biogeochemistry as well as the Research theme ‘Carbon System’ at the Bjerknes Center for Climate research. Information about the supervisor and research possibilities for the fellow is available here.
For further details about the research possibilities please contact Professor Christoph Heinze.
The supervisor: Heinze is a global biogeochemical ocean modeller with 30 years’ experience in the field. His specific research interests are devoted to feedback processes between climate and biogeochemical cycles, the interpretation of the marine sedimentary paleo-climate archive, and the quantification of the global carbon and silicon cycles. Heinze has experience in coordinating large international EU projects (such as the ongoing EU H2020 project COMFORT, https://comfort.w.uib.no/). Heinze has initiated and is leading course GEOF347 at UiB: Seminar on “Earth system science for sustainability studies“.
The research group: The modelling group includes expertise on Earth system modelling, relevant biogeochemical processes and how to implement them in ocean models, numerical computing, mass data analysis, and model experiments with stand-alone ocean models as well as coupled Earth system models. The position is embedded in both the biogeochemistry group at the Geophysical Institute (sub-group on modelling) (https://www.uib.no/en/rg/chemoc) and the Research Theme “Carbon System” at the Bjerknes Centre for Climate Research (https://www.bjerknes.uib.no/en/carbon-system-0).
Available infrastructure: Access to national high-performance computing and mass data storage facilities (Sigma2) is available. The group cooperates with the Bergen and Oslo communities on further developing the Norwegian Earth System Model NorESM. The group currently participates in several other projects involving Earth system modelling funded by the RCN and the EU. A data management group helps concerning archiving/disseminating results.
Research possibilities for the fellow – topical frame: The postdoctoral fellow position is connected to the thematic area of marine biogeochemical hazards. The position is in the field of biogeochemical ocean modelling and model data analysis. The oceans are undergoing fast – in part abrupt – changes in physics, biogeochemistry, and ecosystems under human-induced climate forcing. Warming, ocean acidification, and de-oxygenation provide substantial marine environmental hazards. We employ global coupled Earth system models and global ocean models their results for identifying specific dangerous change, its time of emergence, its temporal behaviour (including persistency and irreversibility), respective early warning indicators, and feasible mitigation options to limit the damage.
Continue reading ‘SEAS postdoctoral research fellow in marine biogeochemical hazards’Reduced pH increases mortality and genotoxicity in an Arctic coastal copepod, Acartia longiremis
Published 6 September 2021 Science ClosedTags: Arctic, biological response, crustaceans, laboratory, molecular biology, mortality, physiology, zooplankton
Highlights
- The fast micromethod for DNA damage analysis was modified for use on copepods.
- Lowered seawater pH causes elevated mortality in Acartia longiremis.
- DNA damage in A. longiremis was elevated after long-term exposure to lowered pH.
Summary
This study investigates DNA damage and mortality in an Arctic marine copepod after long-term exposure to lowered pH. Acartia longiremis were collected from northern Norway and incubated in ambient pH 8.1, and reduced pH 7.6 and 7.2 over 3-4 weeks. Cumulative mortality was significantly elevated in the lowered pH treatments in all exposures. The fluorescence-based fast micromethod for analysis of DNA strand breaks and alkali-labile sites was modified for use on crustaceous zooplankton. DNA damage initially increased in the lowered pH treatments, decreasing after >14 days, and DNA damage was significantly higher in lowered pH conditions. This method is ideal for investigating oxidative stress and genotoxicity response to low pH in Arctic marine copepods exposed to future ocean acidification conditions.
Continue reading ‘Reduced pH increases mortality and genotoxicity in an Arctic coastal copepod, Acartia longiremis’Approaches and involved principles to control pH/pCO2 stability in algal cultures
Published 6 September 2021 Science ClosedTags: algae, biological response, BRcommunity, community composition, laboratory, otherprocess, photosynthesis, physiology, phytoplankton, prokaryotes
Experimental cultures of both microalgae and macroalgae are commonly carried out by phycologists or environmental biologists to look into morphological, physiological, and molecular responses to aquatic environmental changes. However, the species of inorganic carbon in algae cultures is often altered by algal photosynthetic CO2 removal and/or bicarbonate utilization. The pH changes associated with altered carbonate chemistry in cultures impact physiological processes in microalgae and macroalgae even at their exponential growth phases, since extra energy is required to sustain intracellular acid–base homeostasis. Usually, pH increases during light period due to inorganic carbon uptake and utilization for photosynthesis and decreases during dark period because of respiratory CO2 release. Therefore, to obtain relevant data aimed for physiological and/or molecular responses of algae to changed levels of environmental factors, stability of pH/pCO2 in the cultures should be considered and controlled to rule out impacts of carbonate chemistry and pH changes. In this work, principles involved in changing pH processes in algal cultures are mechanistically analyzed and several approaches to control pH and pCO2 are introduced. In order to sustain stability of pH/pCO2, the principles underline the following key points: (1) maintaining the rate of photosynthetic C removal less than or equal to the rate of CO2 dissolution into the cultures which are aerated; or (2) sustaining dilute cultures with very low cell density without aeration, so that photosynthetic C removal is small enough not to cause significant pH/pCO2 changes; or (3) stabilizing the changes in micro-environments surrounding the cells or thallus. To maintain pH drift < 1% in growing typical unicellular microalgae, the recommended cell concentration ranges from 50 × 103 to 200 × 103 mL−1 with aeration (air replacement rate of ca 500–1000 mL L−1 min−1) in semi-continuous cultures of < 1 L, and it ranges from 100 to 5000 cells mL−1 for diatoms and from 100 to 100 × 103 cells mL−1 for coccolithophores in dilute cultures without aeration, respectively. For macroalgae, maintaining the thalli in flowing through- system or in semi-continuous cultures (continuously control algal biomass density) is recommended.
Continue reading ‘Approaches and involved principles to control pH/pCO2 stability in algal cultures’Microbes support enhanced nitrogen requirements of coral holobionts in a high CO2 environment
Published 6 September 2021 Science ClosedTags: archaea, biological response, BRcommunity, community composition, corals, Indian, laboratory, otherprocess, prokaryotes, protists
Ocean acidification is posing a threat to calcifying organisms due to the increased energy requirements of calcification under high CO2 conditions. The ability of scleractinian corals to cope with future ocean conditions will thus depend on their ability to fulfill their carbon requirement. However, the primary productivity of coral holobionts is limited by low nitrogen (N) availability in coral reef waters. Here, we employed CO2 seeps of Tutum Bay (Papua New Guinea) as a natural laboratory to understand how coral holobionts offset their increased energy requirements under high CO2 conditions. Our results demonstrate for the first time that under high pCO2 conditions, N assimilation pathways of Pocillopora damicornis are jointly modified. We found that diazotroph-derived N assimilation rates in the Symbiodiniaceae were significantly higher in comparison to an ambient CO2 control site, concomitant with a restructured diazotroph community and the specific prevalence of an alpha-proteobacterium. Further, corals at the high CO2 site also had increased feeding rates on picoplankton and in particular exhibited selective feeding on Synechococcus sp., known to be rich in N. Given the high abundance of picoplankton in oligotrophic waters at large, our results suggest that corals exhibiting flexible diazotrophic communities and capable of exploiting N-rich picoplankton sources to offset their increased N requirements may be able to cope better in a high pCO2 world.
Continue reading ‘Microbes support enhanced nitrogen requirements of coral holobionts in a high CO2 environment’
