Archive Page 158

Changing tides: how does ocean acidification affect marine life?

Published 31 August 2022 Web sites and blogs Closed

Despite how the ocean has influenced the natural world throughout history, human-triggered global warming is now changing ocean chemistry through a process called ocean acidification. Described by some researchers as “the other CO2 problem”, this phenomenon refers to the reduction in the pH of seawater over time – a change that comes with negative impacts on life above and below the waves. How does ocean acidification affect marine life and humans and what can we do to mitigate its impact?

—

With its powerful tides and vast expanses that stretch into the horizon, the ocean captivates us. It is the cradle of early life – over billions of years our oceans have witnessed the evolution of simple cellular organisms to the wonderfully complex communities we see today. Whether we are standing with our feet in the surf or landlocked thousands of miles from the coast, we are surrounded by the ocean’s influence. By distributing heat, sequestering carbon, and storing solar radiation, it drives weather and climate across the globe. 

What is Ocean Acidification?

Ocean acidification refers to a decrease in the pH of seawater due to increased levels of carbon dioxide (CO2) in the atmosphere. Our oceans are carbon sinks – think of them as sponges that soak up excess carbon from the atmosphere.

By natural processes, CO2 absorbed by the ocean reacts with seawater to create carbonic acid, a weak acid that breaks apart into ions of different charges (imagine ions as Lego pieces that make up a larger structure– in this case,  carbonic acid). These include hydrogen ions and bicarbonate ions. The latter disassociates further to produce additional ions of hydrogen and carbonate. Animals like corals, shellfish, oysters, and urchins  –collectively referred to as calcifiers – use carbonate to build their shells and skeletons.

How does this process change when more CO2 is added to the mix? Since the industrial revolution, the amount of CO2 in the atmosphere has risen nearly 50%, jumping up to nearly 420 parts per million. Our seas currently soak up more than a quarter of the CO2 emitted from human activity. More CO2 in the ocean means more carbonic acid is produced, resulting in extra hydrogen and bicarbonate ions in seawater. pH is determined by the number of free hydrogen ions in a solution; the more they are, the lower the pH (and the more acidic the water). Additional CO2 in the water also leads to a decrease in the bioavailability of carbonate, making it harder for calcifiers to build their shells. 

…

Continue reading ‘Changing tides: how does ocean acidification affect marine life?’

Modeling the sea-surface pCO2 of the central Bay of Bengal region using machine learning algorithms

Published 30 August 2022 Science Closed
Tags: , , , ,

Highlights

  • Performance of MLR, ANN, and XGboost for emulating sea-surface pCO2 is evaluated.
  • XGBoost outperforms MLR and ANN in reproducing sea-surface pCO2.
  • The pCO2 reproducibility using satellite-derived SST and SSS is best using XGBoost.
  • The central BoB has been warming at a rate of 0.0175°C per year during 2010–2019.
  • The sea-surface pCO2 decreases at a rate of −0.4852 μatm per year in the BoB.

Abstract

The present study explores the capabilities of advanced machine learning algorithms in predicting the sea-surface pCO2 (partial pressure of carbon dioxide) in the open oceans of the Bay of Bengal (BoB). We collect the available observations (outside EEZ (Exclusive Economic Zone)) from the cruise tracks and the mooring stations. Due to the paucity of data in the BoB, we attempt to predict pCO2 based on the Sea Surface Temperature (SST) and the Sea Surface Salinity (SSS). Comparing the MLR, the ANN, and the XGBoost algorithm against a common dataset reveals that the XGBoost performs the best for predicting the sea-surface pCO2 in the BoB. Using the satellite-derived SST and SSS, we predict the sea-surface pCO2 using the XGBoost model and compare the same with the in-situ observations. The model performs satisfactorily, having a correlation of 0.75 and the RMSE of ±12.23μatm. Further using this model, we emulate the monthly variations in the sea-surface pCO2 for the central BoB between 2010-2019. Using the satellite data, we show that the central BoB is warming at a rate of 0.0175 °C per year, whereas the SSS decreases at a rate of -0.0088 PSU per year. The modeled pCO2 shows a declination at a rate of −0.4852 μatm per year. We perform sensitivity experiments to find that the variations in SST and SSS contribute ≈ 41% and ≈ 37% to the declining trends of the pCO2 for the last decade. Seasonal analysis shows that the pre-monsoon season has the highest rate of decrease of the sea-surface pCO2.

Continue reading ‘Modeling the sea-surface pCO2 of the central Bay of Bengal region using machine learning algorithms’

Geochemical significance of Acropora death assemblages in the northern South China Sea: implications for environmental reconstruction using branching corals

Published 30 August 2022 Science Closed
Tags: , , , ,

Highlights

  • Acropora-derived SST reconstruction using Sr/Ca has registered SST shifts around 4–5 ka BP and the modern warming.
  • The universal Li/Mg-SST calibration tends to underestimate the SST reconstruction.
  • Reduced pHcf is found for the post-industrial corals compared to the ancient corals.
  • Coral DICcf exhibits a progressive decrease since the mid-Holocene.
  • Skeletal δ13C is intrinsically linked to the coral CF carbonate chemistry.

Abstract

The geochemistry preserved in coral skeletons provides access to pre-instrumental records of environmental changes. While a variety of proxies have been established for coral paleoclimatology, their applications to the use of Acropora to generate longer-term reconstructions have been studied less. Here, we examine the geochemical proxies (i.e., Sr/Ca, Li/Mg, δ18O, δ13C, δ11B, and B/Ca) of dead Acropora assemblages collected from a fringing reef off Hainan Island in the northern South China Sea. These samples have been precisely dated using Usingle bondTh isotopes and record reef development episodes since the mid-Holocene, allowing us to assess their potential as paleoclimate archives. The sea surface temperature (SST) trend reconstructed by Sr/Ca and Li/Mg exhibits better consistency with each other, and they have recorded the SST shifts around 5–4 ka BP and the subdued variability during the Medieval Climate Anomaly (MCA), whereas the δ18O-SST record exhibits less clear variations over the past 7000 years. However, the universal Li/Mg-SST calibration tends to underestimate the SST reconstruction from tropical corals, highlighting the importance of using a site- and species-specific calibration of the Li/Mg-SST. Boron systematics are used to reconstruct the carbonate chemistry of coral calcifying fluid (CF), which reveals significant differences between the ancient and modern corals. The pH of the coral CF (pHcf) is significantly lower in the modern Acropora compared to the ancient corals, with a mean difference of ~0.08 pH, corroborating the pronounced influence of ocean acidification on the coral CF chemistry. The dissolved inorganic carbon of the coral CF (DICcf) is also lower for modern Acropora, and this decreasing trend seems to have persisted over the past 7000 years. In addition, the skeletal δ13C is closely related to the CF carbonate chemistry, highlighting the intrinsic relationship between the coral internal carbon pool used for calcification and the up-regulation of the pHcf.

Continue reading ‘Geochemical significance of Acropora death assemblages in the northern South China Sea: implications for environmental reconstruction using branching corals’

Ocean acidification but not nutrient enrichment reduces grazing and alters diet preference in Littorina littorea

Published 30 August 2022 Science Closed
Tags: , , , , , ,

Ocean acidification and eutrophication have direct, positive effects on the growth of many marine macroalgae, potentially resulting in macroalgal blooms and shifts in ecosystem structure and function. Enhanced growth of macroalgae, however, may be controlled by the presence of grazers. While grazing under ocean acidification and eutrophication conditions has variable responses, there is evidence of these factors indirectly increasing consumption. We tested whether a common marine herbivorous snail, Littorina littorea, would increase consumption rates of macroalgae (Ulva and Fucus) under ocean acidification (increased pCO2) and/or eutrophication conditions, via feeding trials on live and reconstituted algal thalli. We found that increased pCO2 resulted in reduced grazing rates on live thalli, with snails feeding almost exclusively on Ulva. However, eutrophication did not impact consumption rates of live tissues. In addition, similarity in consumption of reconstituted Ulva and Fucus tissues across all treatments indicated that physical characteristics of algal tissues, rather than tissue chemistry, may drive dietary shifts in a changing climate. In this system, decreased consumption, coupled with increased growth of macroalgae, may ultimately enhance algal growth and spread.

Continue reading ‘Ocean acidification but not nutrient enrichment reduces grazing and alters diet preference in Littorina littorea‘

OA-ICC booth at the Virtual Ocean Pavilion on the Road to COP27

Published 30 August 2022 Educational Materials , Events , Presentations Closed

The OA-ICC booth at the Virtual Ocean Pavilion for COP27 opened this week for Africa Climate Week (ACW), being held from 29 August-2 September 2022 in Gabon. Come visit to learn more about OA-ICC news, activities, and resources.

To visit the booth, explore materials from other Virtual Ocean Pavilion exhibitors, and view the schedule of live events, register for an account at the link. The booth and the Virtual Ocean Pavilion will be viewable through the end of COP27.

The Virtual Ocean Pavilion will host two live events this week in the Pavilion Virtual Auditorium. Please review the details below.

  • COP27 Virtual Ocean Pavilion Opening Event: Raising Action: An Ocean of Prospects and Opportunities in 2022 and Beyond
    • 30 August 2022 at 7:00 – 8:30 UTC
    • Speakers: Dr. Manuel Barange, Mr. Richard Delaney, Ms. Landisang Kotaro, Ms. Nozi Mbongwa, Ms. Elisabeth Mrema, Ian Mzee Ngunga, Ambassador Olivier Poivre d’Arvor, Dr. Joanna Post, Dr. Vladimir Ryabinin, Ambassador Peter Thomson, Prof. Carol Turley
  • Ocean and Climate Action: Adaptation and Resilience Practices and Tools Clinic
    • 30 August 2022 at 13:00 – 14:30 UTC
    • Speakers: Dr. Indumathie Hewawasam, Dr. Nayrah Shaltout, Dr. Roshan T. Ramessur, Dr. Bernadette Snow, Dr. Flower Msuya
Continue reading ‘OA-ICC booth at the Virtual Ocean Pavilion on the Road to COP27’

Seasonal variability of carbonate chemistry and its controls in a subtropical estuary

Published 29 August 2022 Science Closed
Tags: , , , ,
Graphical abstract

Highlights

  • The seasonal variability in CO2 system was evaluated in the Patos Lagoon Estuary (PLE) between 2017 and 2021.
  • Mixing between riverine freshwater and seawater drives the changes in the CO2 system in the PLE.
  • The nonthermal effects on seasonal changes in the pCO2 prevail over thermal effects.
  • The waters of PLE are susceptible to CaCO3 undersaturation conditions during winter and spring.
  • The CO2 system in the PLE swings between an ocean-dominated and riverine-dominated estuarine behavior.

Abstract

We performed an unprecedented investigation of the seasonal variability in carbonate system parameters (total alkalinity – AT, total dissolved inorganic carbon – CT, pH, and partial pressure of carbon dioxide – pCO2) in the lower zone of the Patos Lagoon Estuary (PLE), the largest choked lagoon in the world. Sampling was conducted monthly from May 2017 to June 2021. AT and pH were measured during the study period, while other carbonate system parameters were estimated using CO2Sys software. The pH distribution reflected the average natural alkaline conditions throughout the year, with an average of 8.0 pH units. The surface waters in the lower zone of the PLE are generally characterized by a supersaturated calcium carbonate environment. However, a susceptibility to undersaturation conditions was observed during winter (calcite and aragonite) and spring (aragonite). Furthermore, the average surface water pCO2 was 394 μatm during the analyzed period, with the highest values recorded in winter and early spring. The predominant estuarine processes governing changes in the carbonate system in the PLE were the dilution and concentration of salts. These processes depend on the complex balance between freshwater outflows and oceanic inflows that change the surface salinity and produce favorable conditions for primary producer development and the input of continental carbon. However, the remineralization of organic matter and CO2 ingassing likely contribute to the deviations in the theoretical mixing line, causing the increased CT in the region. In addition, the nonthermal effects on seasonal changes in the pCO2 prevail over thermal effects, and the region presents an ocean-dominated (riverine-dominated) condition during summer and autumn (winter and spring). The novel results described here reveal the complexity and challenges that still exist to a better comprehension of how carbonate system parameters evolve temporally and spatially in the PLE, especially considering the climate- and anthropogenic-driven stressors. Finally, this study contributes to the understanding of carbonate system variability in coastal ecosystems and highlights the need for more intense and continuous biogeochemical monitoring of Southern Hemisphere estuaries.

Continue reading ‘Seasonal variability of carbonate chemistry and its controls in a subtropical estuary’

Integrative assessment of biomarker responses in Mytilus galloprovincialis exposed to seawater acidification and copper ions

Published 29 August 2022 Science Closed
Tags: , , , , , , ,
Graphical abstract

Highlights

  • Both OA and Cu ions caused physiological disturbances to the mussel.
  • Mussels have the ability to restore most of the tested parameters from the stress of OA and Cu ions.
  • Gills are more sensitive than digestive glands.
  • IBR analysis demonstrated the co-exposure caused the most brutal impact to the mussel.

Abstract

The interactive effects of ocean acidification (OA) and copper (Cu) ions on the mussel Mytilus galloprovincialis are not well understood. The underlying mechanisms also remain obscure. In this study, individuals of M. galloprovincialis were exposed for 28 days to 25 μg/L and 50 μg/L Cu ions at two pH levels (ambient level – pH 8.1; acidified level – pH 7.6). The mussels were then monitored for 56 days to determine their recovery ability. Physiological parameters (clearance rate and respiration rate), oxidative stress and neurotoxicity biomarkers (activities of superoxide dismutase, lipid peroxidation, catalase, and acetylcholinesterase), as well as the recovery ability of these parameters, were investigated in two typical tissues (i.e., gills and digestive glands). Results showed that (1) OA affected the bioconcentration of Cu in the gills and digestive glands of the mussels; (2) both OA and Cu can lead to physiological disturbance, oxidative stress, cellular damage, energy metabolism disturbance, and neurotoxicity on M. galloprovincialis; (3) gill is more sensitive to OA and Cu than digestive gland; (4) Most of the biochemical and physiological alternations caused by Cu and OA exposures in M. galloprovincialis can be repaired by the recovery experiments; (5) integrated biomarker response (IBR) analysis demonstrated that both OA and Cu ions exposure caused survival stresses to the mussels, with the highest effect shown in the co-exposure treatment. This study highlights the necessity to include OA along with pollutants in future studies to better elucidate the risks of ecological perturbations. The work also sheds light on the recovery of marine animals after short-term environmental stresses when the natural environment has recovered.

Continue reading ‘Integrative assessment of biomarker responses in Mytilus galloprovincialis exposed to seawater acidification and copper ions’

Effects of one-year exposure to ocean acidification on two species of abalone

Published 29 August 2022 Science Closed
Tags: , , , , , ,
Graphical abstract

Highlights

  • Exposure to moderate and high levels of OA increased mortality of adult H. diversicolor, while for H. discus hannai, mortality was increased only under exposure to the high level of OA.

Abstract

Ocean acidification (OA) resulting from the absorption of excess atmospheric CO2 by the ocean threatens the survival of marine calcareous organisms, including mollusks. This study investigated the effects of OA on adults of two abalone species (Haliotis diversicolor, a subtropical species, and Haliotis discus hannai, a temperate species). Abalone were exposed to three pCO2 conditions for 1 year (ambient, ~880, and ~1600 μatm), and parameters, including mortality, physiology, immune system, biochemistry, and carry-over effects, were measured. Survival decreased significantly at 800 μatm pCO2 for H. diversicolor, while H. discus hannai survival was negatively affected only at a higher OA level (~1600 μatm pCO2). H. diversicolor exhibited depressed metabolic and excretion rates and a higher O:N ratio under OA, indicating a shift to lipids as a metabolism substrate, while these physiological parameters in H. discus hannai were robust to OA. Both abalone failed to compensate for the pH decrease of their internal fluids because of the lowered hemolymph pH under OA. However, the reduced hemolymph pH did not affect total hemocyte counts or tested biomarkers. Additionally, H. discus hannai increased its hemolymph protein content under OA, which could indicate enhanced immunity. Larvae produced by adults exposed to the three pCO2 levels were cultured in the same pCO2 conditions and larval deformation and shell length were measured to observe carry-over effects. Enhanced OA tolerance was observed for H. discus hannai exposed under both of the OA treatments, while that was only observed following parental pCO2 ~ 880 μatm exposure for H. diversicolor. Following pCO2 ~ 1600 μatm parental exposure, H. diversicolor offspring exhibited higher deformation and lower shell growth in all pCO2 treatments. In general, H. diversicolor were more susceptible to OA compared with H. discus hannai, suggesting that H. diversicolor could be unable to adapt to acidified oceans in the future.

Continue reading ‘Effects of one-year exposure to ocean acidification on two species of abalone’

Ocean acidification research center student assistant – CFOS (job number: 521478)

Published 29 August 2022 Jobs Closed

Location/School: Fairbanks/UAF College of Fish & Ocean Science

Application dealine: 30 July 2023

Position Summary:

The Ocean Acidification Research Center in the College of Fisheries and Ocean Sciences at UAF is looking for a Student Laboratory Assistant. This position must be performed in-person and offers flexible part-time hours between Monday and Friday, 8am to 5pm, making it easy to accommodate course schedules.

Duties:

The Ocean Acidification Research Center (OARC) is a chemical oceanography laboratory applying quantitative chemical techniques to measure the marine carbonate system. The candidate will work with other OARC members on a variety of laboratory duties including: Analysis of seawater samples, solution preparation, data entry, laboratory supply inventory, shipping and receiving.

Job Overview:

If you enjoy oceanography, chemistry, or environmental sciences and are looking for experience in a research laboratory, consider joining our team! This position is in the Ocean Acidification Research Center in the College of Fisheries and Ocean Sciences at UAF. Visit https://www.uaf.edu/cfos/research/oarc/ to learn more about our research. The ideal candidate will be an eligible UAF student located on the Fairbanks Troth Yeddha’ campus.

Knowledge, Skills, Abilities:

Excellent math skills, ability to compare numbers and identify discrepancies. Microsoft Office skill (i.e. Word and Excel) and Google Drive. Ability to communicate effectively both verbally and in writing. Possess a high level of organizational skills and the ability to work independently with minimal supervision.

…

Required Education or Training:

  • High School Diploma or equivalent.
  • Must be enrolled as a UA student taking a minimum of 6 credit hours with a minimum GPA of 2.0 or a newly enrolled student.
  • UAF laboratory training courses will be given upon acceptance of position.

…

Special Instructions to Applicants:

Please submit a cover letter, resume and the names and contact information (email address and phone number) for three (3) professional references with your application.

The review process for applications will be begin on Tuesday, September 6th.

Continue reading ‘Ocean acidification research center student assistant – CFOS (job number: 521478)’

Monique Keiran: crabs have good reason to be crabby

Published 29 August 2022 Web sites and blogs Closed
Dungeness crab is one of the most commonly caught crab species in B.C., accounting for about 99 per cent of the province’s commercially harvested crab, writes Monique Keiran. Crabmanners via Wikimedia Commons.

…

The Dungeness crab and the razor clam are two of 12 economically and culturally important ocean species along the coast likely to be seriously impacted in multiple ways by climate change over the coming decades, McGill University researchers say.

The researchers modelled how climate is changing the environment within the massive ocean current that flows northwards from California to the outer coast of Vancouver Island. The changes, the researchers recently reported in the journal Global Change Biology, are having knock-on effects within the highly productive coastal marine ecosystem in that underwater ocean superhighway.

The researchers say the biggest responses will occur along the Washington and B.C. coast and in areas close to shore. The region could see substantial losses in kelp forests, declining survival of red urchins, Dungeness crab and razor clams, and losses of anchovy and pink shrimp habitat.

Dungeness crab is one of the most commonly caught crab species in B.C., accounting for about 99 per cent of the province’s commercially harvested crab.

Global carbon emissions drive three main marine stressors — ocean acidification, warming water temperatures and low oxygen levels. The study suggests acidification will have the biggest, most widespread impact on the species.

…

Continue reading ‘Monique Keiran: crabs have good reason to be crabby’

Ocean acidity increased 8.6 percent in New Zealand’s subantarctic surface waters

Published 26 August 2022 Press releases Closed

What is measured

Ocean acidification describes the long-term decrease in the pH of our oceans and coastal waters. This indicator measures:

  • change in pH, acidity, and pCO2 (partial pressure CO2, which is a measure of dissolved carbon dioxide) in New Zealand’s subantarctic surface waters (Munida Transect) from 1998 to 2020
  • pH at selected coastal sites (New Zealand Ocean Acidification Observing Network, NZOA-ON) from 2015 to 2021.

Why it is important

The oceans are a large carbon sink and have very likely absorbed 20–30 percent of the carbon dioxide (CO2) emitted by human activities in the last two decades (Bindoff et al., 2019). CO2 absorption reduces atmospheric greenhouse gas concentrations. However, when seawater absorbs CO2 from the atmosphere, chemical reactions produce hydrogen ions that acidify the seawater and decrease its pH.

…

Continue reading ‘Ocean acidity increased 8.6 percent in New Zealand’s subantarctic surface waters’

Ocean acidification assessment

Published 26 August 2022 Newsletters and reports , Resources , Science Closed
Tags: , , , ,

This report summarises data and analysis methods for ocean acidification data from the Munida Time Series over the period 1998-­2020 and the New Zealand Ocean Acidification Observing Network over the period 2015-­21. Analysis of the trends and variability is also provided along with discussion on the implications of this for the New Zealand marine environment.

Continue reading ‘Ocean acidification assessment’

Editorial: eutrophication, algal bloom, hypoxia and ocean acidification in large river estuaries

Published 26 August 2022 Science Closed
Tags: , , , ,

Editorial on the Research Topic
Eutrophication, algal bloom, hypoxia and ocean acidification in large river estuaries

Estuaries are transitional regions of river freshwater to seawater, and biogeochemical parameters such as salinity, nutrients and biological parameters typically show strong gradients in the offshore direction. Estuaries occupy a small portion of the global ocean area (about 0.2%) but play an important role for marine fisheries and contribute disproportionately to the global carbon budget. Furthermore, estuaries are under multiple strong anthropogenic and climate change pressures, such as eutrophication, wetland degradation, and overfishing, and the ecosystems of many estuaries have dramatically changed, leading to hypoxia, harmful algal blooms, ocean acidification and changes in biodiversity.

In this Research Topic, papers were solicited on estuarine systems that exemplify the changes and the complexities of interactions that are occurring in response to anthropogenic and climate change influences. The ten papers on this Research Topic focus largely–but not exclusively–on Asian waters. Asian waters are among the most rapidly changing and progressively impacted by nutrient enrichment and climate change. One of the major themes of these papers is the coupling between physical and biological processes. The themes herein of physical-biological coupling and impacts on water quality changes were also developed in papers on the Chesapeake Bay and the Salish Sea. Modeling, time series analysis and advanced analytical techniques were all brought to bear in the analyses reported.

…

Continue reading ‘Editorial: eutrophication, algal bloom, hypoxia and ocean acidification in large river estuaries’

Climate resilience and adaptation in West African oyster fisheries: an expert-based assessment of the vulnerability of the oyster Crassostrea tulipa to climate change

Published 26 August 2022 Science Closed
Tags: , , , , ,
Graphical abstract

Globally, over 85% of oyster reefs have been lost, and the combined effects of climate change, ocean acidification, and environmental degradation, including pollution and mangrove overharvesting, could further reduce global oyster fisheries in the coming decades. To understand the level of impact of climate change on the oyster fishery in West Africa, an expert-based vulnerability assessment to climate change was conducted for the West African mangrove oyster (Crassostrea tulipa, Lamarck 1819). Using a combination of the exposure of the oyster to climatic stressors (estuarine temperature, salinity, river flow, surface run-off, sea level rise, and estuarine circulation) together with an assessment of sensitivity to these stressors, we estimate the overall vulnerability of C. tulipa to climate change. A very high overall climate vulnerability score of 12 on a scale of 16 was calculated for C. tulipa. While the overall climate exposure score in the West African coastal region remained high, the high sensitivity of C. tulipa to hydrographic conditions of its habitat, in particular salinity, coupled with its sessile and habitat-specific nature, pushed the overall vulnerability to very high. Early life history settlement requirements, adult mobility, and sensitivity to salinity were the three most important biological and sensitivity attributes that determined the vulnerability score. By leaving each of these three sensitivity attributes out of the analysis, the overall vulnerability score was reduced to 9 (i.e., from very high to high). A negative directional effect of climate change, coupled with a low potential for change in distribution, threatens the C. tulipa fishery in a long-term adverse climate scenario. We recommend management efforts that incorporate climate resilience and adaptation practices to prioritize recruitment success, as well as the development of breeding lines with climate-resilient traits.

Continue reading ‘Climate resilience and adaptation in West African oyster fisheries: an expert-based assessment of the vulnerability of the oyster Crassostrea tulipa to climate change’

Ocean acidification monitoring and scientific research in the PI-TOA region (text & video)

Published 26 August 2022 Presentations , Resources Closed
Tags:

This month’s webinar, “Ocean Acidification Monitoring and Scientific Research in the PI-TOA Region” was held on August 25, 11am Fiji. The webinar was moderated by Dr Kim Currie with presentations by Dr Antoine De Ramon N’Yeurt, Associate Professor Patila Amosa and Ms Luia Taise. The three speakers spanned topics such as establishing a pH time-series on the Suva reef, the effects of ocean acidification on organismal calcification such as corals and bryozoans, and the impacts on the photosynthetic physiology of a green seaweed. These research topics are important in understanding the impact of ocean acidification on coastal ecosystems of the Pacific.

Continue reading ‘Ocean acidification monitoring and scientific research in the PI-TOA region (text & video)’

New study shows larger human-released CO2 increases in subsurface waters of the North Pacific Ocean than in the atmosphere

Published 26 August 2022 Press releases Closed
The modern ocean (blue dashed profiles) reflects the combination of natural, preindustrial conditions (black profiles) and human-induced changes (gray shading). (a) Dissolved inorganic carbon (DIC; µmol kg-1) has increased most near the surface where the ocean absorbs CO2 from the atmosphere. This has caused measurable and distinct changes in (b) pH and (c) pCO2 (µatm). Click on image to enlarge.

The ocean plays a key role in mitigating climate change by absorbing about 25 percent of the carbon dioxide gas (CO2) released into the atmosphere each year by human activities. However, this comes at a cost to ocean health because the uptake of this human-released carbon causes changes in ocean chemistry, called ocean acidification (OA), that can be detrimental to marine ecosystems. 

A University of California – Santa Cruz (UCSC) and NOAA led research team set out to understand how OA metrics, such as pH and the partial pressure of CO2 (pCO2), have changed below the surface waters of the open North Pacific Ocean and coastal California Current System since industrialization (~1750). The California Current Large Marine Ecosystem along the US West Coast is a highly productive coastal ecosystem fueled by seasonal upwelling of cold, nutrient-rich water that supports important fisheries, tourism, and cultural heritage. 

This new research, led by Mar Arroyo, graduate student at UCSC, used observational data from research cruises as part of the GO-SHIP and West Coast Ocean Acidification surveys as well as output from a regional ocean model. The findings were published in the journal Geophysical Research Letters. 

…

Continue reading ‘New study shows larger human-released CO2 increases in subsurface waters of the North Pacific Ocean than in the atmosphere’

Compound extreme events stress the oceans

Published 25 August 2022 Press releases Closed
Sea snails – the picture shows a pteropod – play an important role in the marine food web. They are especially sensitive to ocean warming and acidification. Credit: © Charlotte Havermans

It’s not just the land that is groaning under the heat – the ocean is also suffering from heatwaves. In the Mediterranean Sea along the Italian and Spanish coasts, for example, water temperatures are currently up to 5 °C higher than the long-term average at this time of year. Scientists have investigated marine heatwaves for a few years now – for example at the University of Bern. However, relatively little is known about how marine heatwaves co-occur with other extreme events in the ocean. Such events are known as compound events and considered to be a major risk of climate change. While the processes that lead to extreme events on land, such as floods, forest fires, heatwaves, or droughts and how they interact with each other have been intensively studied in the past, the finding that ocean weather and climate extreme events can also occur in combination is relatively new.

A group of researchers at the Oeschger Center for Climate Change Research, led by Thomas Frölicher, has now investigated whether marine heatwaves co-occur in combination with extreme events in other potential marine ecosystem stressors. In addition to heat, potential stressors also include high acidity levels in the ocean. “For the first time, we have quantified the frequency of compound events in which marine heatwaves happen together with extreme acidity”, says Friedrich Burger, postdoctoral researcher and first author of the study just published in the journal Nature Communications. Extreme events of high ocean acidity are occurrences where the proton concentration in seawater is higher than normal.

…

Continue reading ‘Compound extreme events stress the oceans’

Compound marine heatwaves and ocean acidity extremes

Published 25 August 2022 Science Closed
Tags: , , , , ,

Compound MHW-OAX events, during which marine heatwaves (MHWs) co-occur with ocean acidity extreme (OAX) events, can have larger impacts on marine ecosystems than the individual extremes. Using monthly open-ocean observations over the period 1982–2019, we show that globally 1.8 in 100 months (or about one out of five present-day MHW months) are compound MHW-OAX event months under a present-day baseline, almost twice as many as expected for 90th percentile extreme event exceedances if MHWs and OAX events were statistically independent. Compound MHW-OAX events are most likely in the subtropics (2.7 in 100 months; 10°−40° latitude) and less likely in the equatorial Pacific and the mid-to-high latitudes (0.7 in 100 months; >40° latitude). The likelihood pattern results from opposing effects of temperature and dissolved inorganic carbon on [H+]. The likelihood is higher where the positive effect on [H+] from increased temperatures during MHWs outweighs the negative effect on [H+] from co-occurring decreases in dissolved inorganic carbon. Daily model output from a large-ensemble simulation of an Earth system model is analyzed to assess changes in the MHW-OAX likelihood under climate change. The projected long-term mean warming and acidification trends have the largest effect on the number of MHW-OAX days per year, increasing it from 12 to 265 days per year at 2 °C global warming relative to a fixed pre-industrial baseline. Even when long-term trends are removed, an increase in [H+] variability leads to a 60% increase in the number of MHW-OAX days under 2 °C global warming. These projected increases may cause severe impacts on marine ecosystems.

Continue reading ‘Compound marine heatwaves and ocean acidity extremes’

Increased genetic diversity loss and genetic differentiation in a model marine diatom adapted to ocean warming compared to high CO2

Published 25 August 2022 Science Closed
Tags: , , , , ,

Although high CO2 and warming could act interactively on marine phytoplankton, little is known about the molecular basis for this interaction on an evolutionary scale. Here we explored the adaptation to high CO2 in combination with warming in a model marine diatom Phaeodactylum tricornutum. Whole-genome re-sequencing identifies, in comparison to populations grown under control conditions, a larger genetic diversity loss and a higher genetic differentiation in the populations adapted for 2 years to warming than in those adapted to high CO2. However, this diversity loss was less under high CO2 combined with warming, suggesting that the evolution driven by warming was constrained by high CO2. By integrating genomics, transcriptomics, and physiological data, we found that the underlying molecular basis for this constraint is associated with the expression of genes involved in some key metabolic pathways or biological processes, such as the glyoxylate pathway, amino acid and fatty acid metabolism, and diel variability. Our results shed new light on the evolutionary responses of marine phytoplankton to multiple environmental changes in the context of global change and provide new insights into the molecular basis underpinning interactions among those multiple drivers.

Continue reading ‘Increased genetic diversity loss and genetic differentiation in a model marine diatom adapted to ocean warming compared to high CO2‘

Differential effects of warming and acidification on chemosensory transmission and detection may strengthen non-consumptive effects of blue crab predators (Callinectes sapidus) on mud crab prey (Panopeus herbstii)

Published 25 August 2022 Science Closed
Tags: , , , , , , ,

Predators control prey abundance and behavior, both of which strongly influence community dynamics. However, the relative importance of these predator effects may shift with climate change stressors, suggesting understanding the potential effects on these different processes is critical to predicting effects of climate change on community function. We investigated the effects of global warming and ocean acidification on the transmission and detection of chemical cues from blue crab predators (Callinectes sapidus) by mud crab prey (Panopeus herbstii). We measured mud crab feeding rates in the presence of blue crab predator cues, using either predator cues stressed in acidified conditions or mud crabs stressed in warmed and acidified conditions. Mud crabs consumed less food in the presence of predator cues, but acidifying the cues or subjecting mud crabs receiving the cues to acidified environment did not affect this antipredator response. Mud crabs in warmed conditions consumed significantly less food regardless of predator cue, but this effect was reversed in ambient conditions. Therefore, climate change may produce shifts in community regulation as warming potentially compromises consumptive effects of predators by reducing motor function, whereas non-consumptive effects mediated by sensory transmission and detection remain unaffected by acidification. Overall, warming may have stronger effects than acidification on community dynamics in oyster reefs as global temperatures continue to rise.

Continue reading ‘Differential effects of warming and acidification on chemosensory transmission and detection may strengthen non-consumptive effects of blue crab predators (Callinectes sapidus) on mud crab prey (Panopeus herbstii)’

Subscribe

Search

  • Reset

OA-ICC Highlights

Resources