Etude multi-échelles des échanges air-mer de CO2 et de l’acidification océanique en Manche Occidentale (in French & English)

The anthropogenic impact of the raise of atmospheric CO2 has been observed on the global oceanic scale, resulting in the Ocean Acidification (OA). Largely present in the coastal ecosystems, a decrease of their population could have significant socio-economic consequences. Coastal ecosystems represent only 7% of the global ocean but host a third of the total primary production of the oceans, playing a key role in the global carbon cycle. They are highly diversified and influenced by continental inputs, which complexifies the study of the CO2 cycle. This PhD thesis investigated at different spatial and temporal scales the variability of the carbon cycle in megatidal environments of the North Western European Shelves. From 2015 to 2019, we installed an autonomous sensor of pCO2 (Sunburst SAMI-CO2) on a cardinal buoy located off Roscoff, in the south of the English Channel. Coupled with additional proximal and offshore observations of the carbon cycle and biogeochemical parameters, we were able to describe precisely this ecosystem and assess the tidal, diurnal and interannual variability. Secondly, we followed the variability of these parameters at the decadal scale, based on regular sampling from 2008 to 2018 in two coastal environments very close geographically (Brest and Roscoff, NWES), but with different freshwater influence. Finally, since methane is increasingly considered as a key player in the understanding of the coastal ecosystem functioning and Climatically-Actives Gas cycles, we quantified the driving processes of CO2 and CH4 air-sea exchanges in two mega-tidal estuaries influencing our study region.

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How does ocean acidification affect the early life history of Zostera marina? A series of experiments find parental carryover can benefit viability or germination

Elevated partial pressure of carbon dioxide (pCO2) as a concomitant of global climate change may facilitate the establishment of future seagrass meadows and subsequently its benefit could be incorporated into techniques to increase restoration success. In five manipulative experiments, we determined how increased CO2 affects the maturation of flowers, and the development of seeds and seedlings for the foundation species Zostera marina. Experiments tested the development from both seeds collected from non-treated flowering shoots (direct) and seeds harvested from flowering shoots after CO2 exposure (parental carryover). Flowering shoots were collected along the western coast of Sweden near the island of Skafto. The seeds produced were used in experiments conducted at Kristineberg, Sweden and Dauphin Island, AL, United States. Experiments varied in temperature (16, 18°C) and salinity (19, 33 ppt), as well as duration and magnitude of elevated CO2 exposure. Flowering maturation, spathe number, seed production, and indicators of seed quality did not appear to be affected by 39–69 days of exposure to CO2 conditions outside of natural variability (pCO2 = 1547.2 ± 267.60 μatm; pHT = 7.53 ± 0.07). Yet, seeds produced from these flowers showed twofold greater germination success. In another experiment, flowering shoots were exposed to an extreme CO2 condition (pCO2 = 5950.7 ± 1,849.82 μatm; pHT = 6.96 ± 0.15). In this case, flowers generated seeds that demonstrated a fivefold increase in an indicator for seed viability (sinking velocity). In the latter experiment, however, germination appeared unaffected. Direct CO2 effects on germination and seedling production were not observed. Our results provide evidence of a parental CO2 effect that can benefit germination or seed viability, but early benefits may not lead to bed establishment if other environmental conditions are not well suited for seedling development. Outcomes have implications for restoration; CO2 can be supplied to flowering shoot holding tanks to bolster success when the purpose is to redistribute seeds to locations where beds are extant and water quality is adequate.

Continue reading ‘How does ocean acidification affect the early life history of Zostera marina? A series of experiments find parental carryover can benefit viability or germination’

The key to global warming models is ocean acidity

Ocean acidity is an essential variable in validating climate models, accurately predicting complex environmental dynamics and major changes to Pacific Ocean currents

Recent climate modelling and geochemical data research has confirmed changes to Pacific Ocean currents, including those that impact weather pattern events like El Niño, suggesting they may be more likely to occur with just a few degrees of global warming.

El Niño affects weather extremes, food security, economic productivity, and public safety for a large population of the planet. There is still much discussion as to how well El Niño dynamics are captured by climate models. However, to calculate climate events like El Niño, researchers began measuring ocean acidity rather than water temperature.

Looking beyond ocean temperature and circulation models

Yale climate scientists like Alexey Fedorov have been conducting research on ocean dynamics around the world over the last ten years, analysing events like El Niño, including the warm phase of the El Niño Southern Oscillation, featuring abnormally warm water in the Pacific.

Fedorov developed climate model simulations that look at ocean temperature proxies of the distant past, when global temperatures were several degrees warmer, as well as the present, to predict what might happen in the future, when the world is probably going to be warmer.

The climate scientists aimed to look at whether ancient temperature data in their models and other climate models were accurately capturing the past climate state.

Lead author Madison Shankle, a former Yale researcher now at the University of St Andrews School of Earth and Environmental Sciences, said: “Accurately capturing ocean dynamics in the equatorial Pacific in global climate models is crucial for predicting regional climate in the warmer decades to come.”

Pincelli Hull, Assistant Professor of Earth and Planetary Sciences in Yale’s Faculty of Arts and Sciences and principal investigator for the new study, said: “We decided to test model predictions of major changes to the winds and currents driving El Niño by measuring something else, rather than temperature. We measured ocean acidity instead.”

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Guest post: why oceans could face more extremes like the Pacific ‘Blob’

The devastating impact of extreme weather is etched into our collective memory. In 2021 alone, the world saw record-shattering heat in western North America, deadly floods in Europe, China and west Africa, and wildfires in the Mediterranean. 

But alongside these events happening on land, the oceans experience extreme conditions too. In 2015, the North Pacific saw the largest marine heatwave ever recorded, known simply as the “Blob”.

As Earth warms, marine heatwaves are likely to become more intense, happen more often and last longer. But as our recent paper in Nature explains, we are also set to see more occasions – as with the “Blob” – where two or more types of extreme events occur simultaneously. 

These “compound” events likely have more devastating impacts than a single heatwave, affecting marine life such as tiny floating plantsseabirds and sea lions.

The ‘Blob’ in the Pacific

In 2015-16, much of the tropical Pacific was experiencing record high sea surface temperatures associated with a strong El Niño event, causing widespread bleaching and death of coral reefs. 

At the same time, the North Pacific was seeing extreme warmth, in an event that became known as the “Blob”. At its peak in 2015, the Blob covered about 4m square kilometres (km2) of ocean, stretching from Alaska to Baja California.  

Unsurprisingly, the Blob caught the headlines at the time. National Geographic, for example, described it as, “The blob that cooked the Pacific”. Some of the ecological consequences of the Blob are still lingering today, with several marine animal populations not having fully recovered.

A ‘triple-compound’ extreme event

Our research used simulations from a regional ocean biogeochemical model to explore not only the extreme heat that characterised the Blob, but also whether the upper water column in the northeast Pacific at the time was unusual in other ways too. In particular, with respect to its oxygen levels and acidity (measured by the pH of the seawater).

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Biogeochemical extremes and compound events in the ocean

The ocean is warming, losing oxygen and being acidified, primarily as a result of anthropogenic carbon emissions. With ocean warming, acidification and deoxygenation projected to increase for decades, extreme events, such as marine heatwaves, will intensify, occur more often, persist for longer periods of time and extend over larger regions. Nevertheless, our understanding of oceanic extreme events that are associated with warming, low oxygen concentrations or high acidity, as well as their impacts on marine ecosystems, remains limited. Compound events—that is, multiple extreme events that occur simultaneously or in close sequence—are of particular concern, as their individual effects may interact synergistically. Here we assess patterns and trends in open ocean extremes based on the existing literature as well as global and regional model simulations. Furthermore, we discuss the potential impacts of individual and compound extremes on marine organisms and ecosystems. We propose a pathway to improve the understanding of extreme events and the capacity of marine life to respond to them. The conditions exhibited by present extreme events may be a harbinger of what may become normal in the future. As a consequence, pursuing this research effort may also help us to better understand the responses of marine organisms and ecosystems to future climate change.

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The responses of harmful dinoflagellate Karenia mikimotoi to simulated ocean acidification at the transcriptional level

Highlights

  • 1121 genes were up- and 1369 down-regulated in K. mikimotoi upon ocean acidification (OA).
  • OA led to down-regulation of carbon concentration mechanism-related factors.
  • OA up-regulated energy metabolism, boosting growth and enhancing pigment content.
  • Increased CAT and GR activities helped acclimate to OA.
  • Up-regulated HSP genes enhanced tolerance of cells to low pH caused by OA.

Abstract

The HAB-forming, toxic dinoflagellate Karenia mikimotoi, previously found to benefit from ocean acidification (OA), was cultivated to investigate its transcriptional response to simulated OA for 30 generations. Batch cultures were grown under two CO2 concentrations, 450 (control) and 1100 (simulated OA) μatm, and physiological parameters [growth, pigments, catalase (CAT), glutathione reductase (GR), and superoxide dismutase (SOD) activity], as well as transcriptomes (obtained via RNA-seq), were compared. Chlorophyll a (Chl a) and carotenoid (Caro) contents, as well as CAT and GR activities, were significantly increased under OA conditions. Transcriptomic analysis revealed 2,490 differentially expressed unigenes in response to OA, which comprised 1.54% of all unigenes. A total of 1,121 unigenes were upregulated, and 1,369 unigenes were downregulated in OA compared to control conditions. The downregulated expression of bicarbonate transporter and carbonic anhydrase genes was a landmark of OA acclimation. Key genes involved in energy metabolism, e.g., photosynthesis, tricarboxylic acid cycle, oxidative phosphorylation, and nitrogen metabolism, were highly upregulated under OA, contributing to increases in the Chl a (55.05%) and Caro (28.37%). The enhanced antioxidant enzyme activities (i.e. CAT, GR) and upregulated genes (i.e. glutathione peroxidase, ascorbate peroxidase, heat shock protein, 20S proteasome, aldehyde dehydrogenase, and apolipoprotein) benefit cells against the potential lower pH stress condition under OA. In addition, the downregulation of four genes associated with motility suggested that the preserved energy could further boost growth. In conclusion, the present study suggests that K. mikimotoi exhibits efficient gene expression regulation for the utilization of energy and resistance to OA-induced stress. Taken together, K. mikimotoi appeared as a tolerant species in response to OA. Thus, more extensive algal blooms that threaten marine organisms are likely in the future. These findings expand current knowledge on the gene expression of HAB-forming species in response to future OA.

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Internal controls for quantitative RT-PCR analysis of gene expression in response to ocean acidification in edible oysters

The increase of CO2 by anthropogenic activities leads to a decrease of pH in the ocean surface due to ocean acidification (OA) process. Generally, OA not only reduces the rate of calcification in marine environments but also affects various physiological activities, especially in calcifiers, including edible oysters. Quantitative real-time PCR (qRT-PCR) is often used to detect gene expression in response to OA, which relies on the stability of internal control. However, the appropriate internal controls for OA experiments remain scarce especially in the marine calcifiers. Hence, this study developed internal controls for qRT-PCR assays using the Hong Kong oyster (Crassostrea hongkongensis) as a model to reveal gene expression profile during development under OA. In this study, 17 housekeeping genes were selected as the possible candidate of the internal controls. After a comprehensive interpretation from the multiple algorithms and software, GAPDH paired with RL23 is recommended for the normalization for planktonic larvae and benthic juveniles, but beyond that, TUBB and EF2 are recommended for post-metamorphic stage. Moreover, GAPDH and EF2 were suitable for various pH treatments, and TUBB, RL35 and RL23 could be the alternatives for OA experiments. These results are instrumental for the selection of internal control in Crassostrea hongkongensis during the development, and shed light on other molecular OA experiments in marine invertebrates for reference.

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Seasonal variability and future projection of ocean acidification on the East China Sea shelf off the Changjiang Estuary

Ocean acidification (OA) occurs universally in the world’s oceans. Marginal seas are facing more serious OA than the open ocean due to strong anthropogenic and natural impacts. This study investigates carbonate dynamics on the East China Sea (ECS) shelf off the Changjiang Estuary using field observations made from 2015 to 2019 that cover all four seasons. In the low productivity cold seasons, the water was well-mixed vertically. The coastal area and the northern ECS were occupied by water characterized by high dissolved inorganic carbon (DIC), low pH25 (pH at 25°C), and low ΩAr (saturation state index of aragonite), and influenced by the coastal water from the Yellow Sea (YS). However, during highly productive warm seasons, pH25 and ΩAr increased in the surface water but decreased in the bottom water as a result of strong biological DIC uptake in the surface water and CO2 production by strong organic matter remineralization in the bottom water. Strong remineralization decreased pH25 and ΩAr by 0.18 ± 0.08 and 0.73 ± 0.35 in the hypoxic bottom water in summer, even though the bottom water remained oversaturated with respect to aragonite (ΩAr > 1.0) during the surveys. Under the context of global OA and the strong seasonal acidification, the projected bottom water on the ECS shelf will be corrosive for aragonite by mid-century.

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In situ skeletal growth rates of the solitary cold-water coral Tethocyathus endesa from the Chilean Fjord region

Cold-water corals (CWC) can be found throughout a wide range of latitudes (79°N–78°S). Since they lack the photosymbiosis known for most of their tropical counterparts, they may thrive below the euphotic zone. Consequently, their growth predominantly depends on the prevalent environmental conditions, such as general food availability, seawater chemistry, currents, and temperature. Most CWC communities live in regions that will face CaCO3 undersaturation by the end of the century and are thus predicted to be threatened by ocean acidification (OA). This scenario is especially true for species inhabiting the Chilean fjord system, where present-day carbonate water chemistry already reaches values predicted for the end of the century. To understand the effect of the prevailing environmental conditions on the biomineralization of the CWC Tethocyathus endesa, a solitary scleractinian widely distributed in the Chilean Comau Fjord, a 12-month in situ experiment was conducted. The in situ skeletal growth of the test corals was assessed at two sites using the buoyant weight method. Sites were chosen to cover the naturally present carbonate chemistry gradient, with pH levels ranging between 7.90 ± 0.01 (mean ± SD) and 7.70 ± 0.02, and an aragonite saturation (Ωarag) between 1.47 ± 0.03 and 0.98 ± 0.05. The findings of this study provide one of the first in situ growth assessments of a solitary CWC species, with a skeletal mass increase of 46 ± 28 mg per year and individual, at a rate of 0.03 ± 0.02% day. They also indicate that, although the local seawater chemistry can be assumed to be unfavorable for calcification, growth rates of T. endesa are comparable to other cold-water scleractinians in less corrosive waters (e.g., Lophelia pertusa in the Mediterranean Sea).

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Regulation of the coral-associated bacteria and symbiodiniaceae in Acropora valida under ocean acidification

Ocean acidification is one of many stressors that coral reef ecosystems are currently contending with. Thus, understanding the response of key symbiotic microbes to ocean acidification is of great significance for understanding the adaptation mechanism and development trend of coral holobionts. Here, high-throughput sequencing technology was employed to investigate the coral-associated bacteria and Symbiodiniaceae of the ecologically important coral Acropora valida exposed to different pH gradients. After 30 days of acclimatization, we set four acidification gradients (pH 8.2, 7.8, 7.4, and 7.2, respectively), and each pH condition was applied for 10 days, with the whole experiment lasting for 70 days. Although the Symbiodiniaceae density decreased significantly, the coral did not appear to be bleached, and the real-time photosynthetic rate did not change significantly, indicating that A. valida has strong tolerance to acidification. Moreover, the Symbiodiniaceae community composition was hardly affected by ocean acidification, with the C1 subclade (Cladocopium goreaui) being dominant among the Symbiodiniaceae dominant types. The relative abundance of the Symbiodiniaceae background types was significantly higher at pH 7.2, indicating that ocean acidification might increase the stability of the community composition by regulating the Symbiodiniaceae rare biosphere. Furthermore, the stable symbiosis between the C1 subclade and coral host may contribute to the stability of the real-time photosynthetic efficiency. Finally, concerning the coral-associated bacteria, the stable symbiosis between Endozoicomonas and coral host is likely to help them adapt to ocean acidification. The significant increase in the relative abundance of Cyanobacteria at pH 7.2 may also compensate for the photosynthesis efficiency of a coral holobiont. In summary, this study suggests that the combined response of key symbiotic microbes helps the whole coral host resist the threats of ocean acidification.

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The combined effects of ocean acidification and heavy metals on marine organisms: a meta-analysis

Ocean acidification (OA) may interact with anthropogenic pollutants, such as heavy metals (HM), to represent a threat to marine organisms and ecosystems. Here, we perform a quantitative meta-analysis to examine the combined effects of OA and heavy metals on marine organisms. The results reveal predominantly additive interactions (67%), with a considerable proportion of synergistic interactions (25%) and a few antagonistic interactions (8%). The overall adverse effects of heavy metals on marine organisms were alleviated by OA, leading to a neutral impact of heavy metals in combination with OA. However, different taxonomic groups showed large variabilities in their responses, with microalgae being the most sensitive when exposed to heavy metals and OA, and having the highest proportion of antagonistic interactions. Furthermore, the variations in interaction type frequencies are related to climate regions and heavy metal properties, with antagonistic interactions accounting for the highest proportion in temperate regions (28%) and when exposed to Zn (52%). Our study provides a comprehensive insight into the interactive effects of OA and HM on marine organisms, and highlights the importance of further investigating the responses of different marine taxonomic groups from various geographic locations to the combined stress of OA and HM.

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$50M gift aims to improve Hawaiʻi’s ocean health

Seven-Year Commitment Funds University of Hawaiʻi at Mānoa SOEST Ocean Conservation Research

Today, the University of Hawaiʻi at Mānoa’s School of Ocean and Earth Science and Technology (SOEST) announced a seven-year $50 million commitment from Dr. Priscilla Chan and Mark Zuckerberg, which will support  various research groups within Hawaiʻi Institute of Marine Biology (HIMB). HIMB will leverage this gift to make meaningful progress in restoring Hawaiʻi’s ocean health. 

This gift will fund research and programs that document changing ocean conditions, explore solutions to support healthier ocean ecosystems, enhance coastal resilience from storms and sea-level rise, and tackle challenges to marine organisms ranging from the tiniest corals to the largest predators.

University of Hawai‘i (UH) President David Lassner said, “This transformative gift will enable our world-class experts to accelerate conservation research for the benefit of Hawaiʻi and the world.” Lassner continued, “The ocean ecosystems that evolved over eons now face unprecedented threats from our growing human population and our behaviors. It is critical that we learn from previous generations who carefully balanced resource use and conservation. The clock is ticking, and we must fast-track not only our understanding of marine ecosystems and the impacts of climate change, but the actions we must take to reverse the devastation underway. There is no place on Earth better than Hawai‘i to do this work, and no institution better able than UH.  We could not be more grateful for the investment of Dr. Priscilla Chan and Mark Zuckerberg in a better future for all of us and our planet.” 

Hawai‘i is home to a rich diversity of marine life, including many threatened and endangered species. The accelerated pace of climate change and ocean acidification has altered environmental conditions faster than expected. Many species have difficulty adapting to the rapid changes taking place in the oceans and scientists see growing impacts to marine ecosystems. 

The gift funds research on the impact of climate change on Hawaiian coastal waters, including areas of particular concern or natural refuges from ocean acidification effects. It will also support  research  on methods for more accurate forecasting of future ocean conditions, as well as efforts to study marine organisms like coral reefs, sharks, and other species.    

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Postdoctoral researcher: EASMO (reference number 221-EASMO)

The Leibniz Centre for Tropical Marine Research (ZMT) in Bremen is a member of the Leibniz Association, which is supported by the German Federal and State Governments. Through its research, ZMT contributes to developing strategies for sustainable use of tropical coastal systems.

Project rationale and summary:

Species are “on the move” throughout the planet escaping hostile climatic conditions. These movements have advanced four times faster in the ocean than on land, causing dramatic ecosystem changes and redistributing resources across borders. The ecological, food security, and governance implications are obvious. Yet, two persistent gaps hinder our capacity to effectively manage coastal social-ecological systems to safeguard both fisheries and human wellbeing in the face of such challenges: i) regional studies documenting recent species redistributions have not quantified the societal repercussions, and ii) future projections have mapped expected catches and metrics of socio-economic impact (e.g. fisheries revenue) globally and at coarse resolutions, unfitting to support local or regional decision-making. Fish redistributions are particularly concerning, as three billion people depend on them for 15% of their animal protein intake and essential nutrients to tackle malnutrition. Although fish range shifts should be urgently investigated in the Global South, studies have focused disproportionately on wealthy parts of the world. EASMO will investigate for the first time the impact of climate change on the distribution of reef fish throughout the Eastern Tropical Pacific Ocean (ETP) considering cascading effects on biodiversity, ecosystem function, reefs’ contributions to people, climate feedbacks, and socio-economic wellbeing. Ultimately, it will deliver several layers of new scientific knowledge that can be directly integrated into decision-making tools, support adaptive transboundary governance approaches, and propel actions for meeting the UN Sustainable Development Goals 2 Zero hunger, 13 Climate action, and 14 Life below water. Find more details on the project here.

Selection criteria:

  • PhD degree on marine fish ecophysiology, species distribution modelling and climate change ecology
  • Knowledge on behavioural and physiological responses of fish to climate stressors (ocean warming and acidification)
  • Practical experience in fish husbandry and experimental ecology and conducting single and/or multi-stressor climate change experiments on fish
  • Research experience integrating empirical datasets across biological levels and/or into statistical models
  • Familiarity and experience in modelling future climate change effects on species distribution
  • Interest and knowledge on the effects of ocean acidification on fish and the pathways through which fish may affect the ocean’s carbonate chemistry
  • Attention to detail and demonstrated proficiency in managing large datasets
  • Strong analytical skills including demonstrated proficiency in applying a broad range of basic to advanced modelling and statistical analysis tools
  • Demonstrated excellence in English scientific writing and oral communication
  • A positive collaborative work ethics that promotes diversity, equality, and inclusiveness
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Climate change, marine resources and a small Chilean community: making the connections

Climate change is affecting large-scale oceanic processes. How and when these changes will impact those reliant on marine resources is not yet clear. Here we use end-to-end modeling to track the impacts of expected changes through the marine ecosystem on a specific, small community: Cochamó, in the Gulf of Ancud wider area, Chile. This area is important for Chilean fisheries and aquaculture, with Cochamó reliant on both lower and upper trophic level marine resources. We applied the GOTM-ERSEM-BFM coupled hydro-biogeochemical water-column model to gauge lower-trophic level marine ecological community response to bottom-up stressors (climate change, ocean acidification), coupled to an existing Ecopath with Ecosim model for the area, which included top-down stressors (fishing). Social scientists also used participatory modeling (Systems Thinking and Bayesian Belief Networking) to identify key resources for Cochamó residents and to assess the community’s vulnerability to possible changes in key resources. Modeling results suggest that flagellate phytoplankton abundance will increase at the cost of other species (particularly diatoms), resulting in a greater risk of harmful algae blooms. Both climate change and acidification slightly increased primary production in the model. Higher trophic level results indicate that some targeted pelagic resources will decline (while benthic ones may benefit), but that these effects might be mitigated by strong fisheries management efforts. Participatory modeling suggests that Cochamó inhabitants anticipate marine ecosystem changes but are divided about possible adaptation strategies. For climate change impact quantification, detailed experimental studies are recommended based on the dominant threats identified here, with specific local species.

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The Southern Ocean diatom Pseudo-nitzschia subcurvata flourished better under simulated glacial than interglacial ocean conditions: combined effects of CO2 and iron

The ‘Iron Hypothesis’ suggests a fertilization of the Southern Ocean by increased dust deposition in glacial times. This promoted high primary productivity and contributed to lower atmospheric pCO2. In this study, the diatom Pseudo-nitzschia subcurvata, known to form prominent blooms in the Southern Ocean, was grown under simulated glacial and interglacial climatic conditions to understand how iron (Fe) availability (no Fe or Fe addition) in conjunction with different pCO2 levels (190 and 290 μatm) influences growth, particulate organic carbon (POC) production and photophysiology. Under both glacial and interglacial conditions, the diatom grew with similar rates. In comparison, glacial conditions (190 μatm pCO2 and Fe input) favored POC production by Psubcurvata while under interglacial conditions (290 μatm pCO2 and Fe deficiency) POC production was reduced, indicating a negative effect caused by higher pCO2 and low Fe availability. Under interglacial conditions, the diatom had, however, thicker silica shells. Overall, our results show that the combination of higher Fe availability with low pCO2, present during the glacial ocean, was beneficial for the diatom Psubcurvata, thus contributing more to primary production during glacial compared to interglacial times. Under the interglacial ocean conditions, on the other hand, the diatom could have contributed to higher carbon export due to its higher degree of silicification.

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Ocean acidification crisis and global warming observations from tropical corals (text & video)

Human induced increases in atmospheric CO2 levels are warming the Earth’s ocean and also increasing the acidity of our shallow marine environments. This process, known as ocean acidification (OA), is caused by the absorption of atmospheric CO2 by the oceans and is threatening the ability of calcifying organisms to build their calcium carbonate skeletons. Our current understanding of the changes caused by OA in the tropical oceans is severely limited due to the lack of reliable long-term seawater pH monitoring and the difficulty in reconstructing past changes in pH and ocean chemistry in these remote environments. This project uses techniques to reconstruct past seawater conditions from long-living corals to observe the evolution of pH and carbonate chemistry in our tropical oceans. Improved multi-proxy techniques are also applied to observe sea surface temperature and hydroclimate changes over the past few hundred years to provide a historical context to our current climate crisis.

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VIU science and technology community lecture series: ocean acidification in British Columbia’s coastal waters

Date: 2 March 2022

Time: 7:00 – 8:00 pm

Location: virtual

Description: Ocean acidification is a chemical change in seawater that is caused by the uptake of carbon dioxide from the atmosphere. As carbon dioxide increases in the atmosphere from human activity, this chemical change intensifies and impacts marine life. This talk will review what we know and what we need to know about the patterns and impacts of ocean acidification in British Columbia coastal waters.

Bio: Dr. Wiley Evans is a chemical oceanographer at the Hakai Institute in British Columbia, Canada. He completed his PhD at Oregon State University studying carbon dioxide exchange between the ocean and atmosphere from northern California to southeast Alaska. He then worked on monitoring ocean acidification as a postdoctoral researcher at the University of Alaska Fairbanks, and then as a research associate at the U.S. National Oceanic and Atmospheric Administration’s Pacific Marine Environmental Laboratory before joining the Hakai Institute. Wiley manages Hakai Institute’s Ocean Acidification Program and is the co‐chair for the British Columbia Ocean Acidification and Hypoxia Action Plan led by the Ministry of Agriculture, Food and Fisheries.

Vancouver Island University’s (VIU’s) spring 2022 Science and Technology Lecture Series is shining the spotlight on climate change research.

“Climate change is one of the greatest challenges currently facing humanity, and everyone will be impacted by the rapid environmental changes that are currently occurring on Earth,” says Dr. Tim Stokes, a VIU Earth Sciences Professor and the series coordinator and organizer.

At each lecture, researchers will share their findings on climate change science and delve into topics such as investigating changing snowpacks in Coastal BC, water resource management on Vancouver Island, and tracking past shifts in sea levels and their effects on humans. The Science and Technology Lecture Series has been offered almost every spring term for the last 15 years and was created as an opportunity for researchers to share their findings on a range of different science issues and topics with the VIU community and the public.

The series runs on Wednesdays, from 7-8 pm, from January 19 to April 6. There is no lecture on February 23, during VIU’s Reading Week. Lectures are offered in-person at Building 355, Room 203 at VIU’s Nanaimo campus and most lectures will be live streamed via Zoom. In-person attendance is at a reduced capacity of 50% and attendees must provide proof of vaccination and wear masks at all times. For Zoom links or to register to attend in-person lectures please visit the Science and Technology Community Lecture Series website.

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Impact of ocean acidification on physiology and microbiota in hepatopancreas of Pacific oyster Crassostrea gigas

The hepatopancreas is an important tissue involved in various biological metabolism for mollusks, but its responses to ocean acidification (OA) have not been well evaluated. In this study, the oysters were cultured in simulated conditions by continuously bubbling with ambient air (pH=8.10) or air-CO2 (pH=7.50) for up to two months, and the variations on the antioxidant capacity, digestive ability, and microbiota composition in hepatopancreas of Crassostrea gigas were analyzed. The results show that although superoxide dismutase and glutathione responded quickly to OA stress, the antioxidant capacity of the hepatopancreas was inhibited, as revealed by the decrease of the total antioxidant capacity, which led to an upward trend of the malondialdehyde, demonstrating that the oxidative damages were accumulated under the OA process. The determination of the digestive ability manifested as the decrease of pepsin activity and the recovery of lipase and amylase activity after long-term acidification, which may be helpful to improve the adaptability of oysters. In addition, analysis on 16S rDNA amplicon revealed that the total species abundance and diversity of the hepatopancreas microbiota experienced a dynamic change, but finally it decreased greatly after long-term acidification. The structure of the hepatopancreas microbiota was changed drastically with the change of the dominant species from aerobic to the anaerobic and facultative anaerobic bacteria, and the abnormal proliferation of some species, such as genus of Mycoplasma and order Clostridiales, which may aggravate the adverse effects of OA on the physiological functions of the hepatopancreas. As a result, our findings enrich our understanding of the accumulated oxidative damage and adaptive digestive ability in oyster hepatopancreas caused by OA. For the first time, the changes of the hepatopancreas microbiota under long-term acidification conditions are described, proving a good reference for the study of the response and adaptation mechanisms of bivalve mollusks in a wide range of oceans OA.

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Effects of water acidification on immune responses of the gercacinid,
Cardiosoma armatum (Herklots, 1851)

The biological response to chemical pollutants reflects the acid–base status of an aquatic ecosystem. The gercacinid, Cardiosoma armatum (75±0.1 g) was exposed to acidified waters to evaluate the effects on its immune parameters. The crabs were exposed to pH 4.0, 5.0, 6.0 and 7.8 (control) for 28 days. The hematological parameters of control crabs and crabs exposed to varied doses of acidified water indicated a marked reduction. Significant (p<0.05) higher alkaline phosphatase and albumen were obtained in pH 4.0, 5.0 and 6.0 compared to control; other values were mostly similar to control. The highest superoxide dismutase (SOD) (252.61±0.06 min/mg pro) was recorded in control group, while highest CAT activity (2.08±0.16 min/mg protein) was recorded in crabs exposed to pH 4 treatment. Furthermore, the control group’s SOD activity was significantly higher than the exposed groups. With a lower pH, the quantities of malondialdehyde increased substantially and were significantly different from the control group. While these findings demonstrate that changes in pH have limited impact on energy use, decreasing immune system conditions show that C. armatum is susceptible to pH variations and may be influenced in aquaculture, where a pH drop is more prominent.

Continue reading ‘Effects of water acidification on immune responses of the gercacinid,
Cardiosoma armatum (Herklots, 1851)’

Basic training course on ocean acidification

Date: 14 – 19 March 2022

Location: The Kristineberg Marine Research Station, University of Gothenburg, Sweden

Deadline for applications: 24 January 2022

Background Information: The course will be based on previous courses on ocean acidification held as part of the activities of the IAEA Peaceful Uses Initiative project “Ocean Acidification International Coordination Centre” (OA-ICC) and partners, and the document “Guide to Best Practices in Ocean Acidification Research and Data Reporting” (see http://www.iaea.org/ocean-acidification/page.php?page=2194).

Purpose: To train early-career scientists and researchers entering the ocean acidification field with the goal to assist them to be able to measure and manipulate seawater carbonate chemistry, set up pertinent experiments, avoid typical pitfalls and ensure comparability with other studies, in a sustainable way.

Expected Outputs: Increased capacity to measure and study ocean acidification and increased networking among scientists working on ocean acidification. Initiate/deepen connections with international networks such as the Global Ocean Acidification Observing Network (GOA-ON).

Scope and Nature: The training will include lectures in plenary and hands-on experiments in smaller groups (the level will depend on the basic knowledge of the selected participants). Subjects to be covered include: theoretical aspects of ocean acidification from chemistry to society, the characterization of the seawater carbonate chemistry including making TRIS buffer, calibration of pH electrodes, measurement of alkalinity, software packages used to calculate CO2 system parameters, key aspects of ocean acidification experimental design, such as manipulation of seawater chemistry, biological perturbation approaches, and lab- and field-based methods for measuring organism responses to seawater chemistry changes, including nuclear and isotopic techniques.

Participation: The course is open to 15 trainees. Priority will be given to early-career scientists who begin to work in the ocean acidification area. Experts interested in starting ocean acidification studies would be welcome, space permitting. As identified by the Global Ocean Acidification Observing Network (GOA-ON) European hub, there is a strong need for capacity building in Europe. For this training, priority will be given to European but applications from other countries are welcome.

Qualifications: The participants should have a university degree in marine chemistry, biology, oceanography or a related scientific field, and should be currently involved in or planning to set up ocean acidification studies.

Application Procedure: Selection will be based on merit and interest. Your applications should include:

  • A motivation letter with a short description of your research interest, why you would like to participate, and your plans regarding present and future ocean acidification research (max one A4 page)
  • CV with publication list
  • Applications must be received by not later than 24 January 2022 for the attention of the course organizer, Dr. Sam Dupont (sam.dupont@bioenv.gu.se).
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