Synthesis of thresholds of ocean acidification impacts on decapods

Assessing decapod sensitivity to regional-scale ocean acidification (OA) conditions is limited because of a fragmented understanding of the thresholds at which they exhibit biological response. To address this need, we undertook a three-step data synthesis: first, we compiled a dataset composed of 27,000 datapoints from 55 studies of decapod responses to OA. Second, we used statistical threshold analyses to identify OA thresholds using pH as a proxy for 13 response pathways from physiology to behavior, growth, development and survival. Third, we worked with the panel of experts to review these thresholds, considering the contributing datasets based on quality of the study, and assign a final thresholds and associated confidence scores based on quality and consistency of findings among studies. The duration-dependent thresholds were within a pH range from 7.40 to 7.80, ranging from behavioral and physiological responses to mortality, with many of the thresholds being assigned medium-to-high confidence. Organism sensitivity increased with the duration of exposure but was not linked to a specific life-stage. The thresholds that emerge from our analyses provide the foundation for consistent interpretation of OA monitoring data or numerical ocean model simulations to support climate change marine vulnerability assessments and evaluation of ocean management strategies.

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Spatial and temporal variations of aragonite saturation states in the surface waters of the western Arctic Ocean

Abstract

The aragonite saturation state (Ωarag) was determined for the surface waters of the western Arctic Ocean over three years, from 2016 to 2018, in an investigation of the present state of acidification of its waters and the main factors controlling the spatial and temporal variations in the surface Ωarag. The study area was divided into the Chukchi marginal area (CMA) and the East Siberian marginal area (ESMA) along a longitude of 180°E. In the CMA, the surface Ωarag during the study period ranged from 0.86 to 1.77, with an average of 1.16, indicating near saturation with respect to aragonite. In the ESMA, the surface Ωarag during the study period ranged from 1.01 to 2.21, with a higher average (1.59) than the CMA. Aragonite undersaturation in the ESMA was not observed during any of the measurement periods, so ocean acidification was less serious there than in the CMA. The surface Ωarag of the CMA was mainly determined by the mixing of seawater and freshwater introduced from rivers and/or sea ice, whereas in the ESMA it was influenced by the mixing of seawater and freshwater but also biological production and lateral mixing.

Plain Language Summary

The study was conducted in the western Arctic Ocean and included the Northwind Ridge, Chukchi Plateau, Chukchi Abyssal Plain, Chukchi Sea Slope, East Siberian Sea Slope, and Mendeleyev Ridge. The waters encompassed by these sites are highly vulnerable to acidification because of the inflow of lower-pH water from the Pacific Ocean through the Bering Sea and the current rapid reduction in the amount of sea ice. The study area was divided into the Chukchi marginal area (CMA) and the East Siberian marginal area (ESMA) along a longitude of 180°E. In the CMA, the surface waters were almost saturated with respect to aragonite but in the ESMA they were undersaturated, indicating that oceanic acidification was more serious in the CMA than in the ESMA. In the near future, the aragonite undersaturation in the most of the surface waters of the CMA will prohibit the survival of calcareous organisms and may lead to their extinction from this area. However, a similar short-term scenario is not expected in the ESMA, due to its relatively high biological production, which favors aragonite saturation and will thus delay aragonite undersaturation of the surface water.

Continue reading ‘Spatial and temporal variations of aragonite saturation states in the surface waters of the western Arctic Ocean’

Calcium carbonate prevents Botryococcus braunii growth inhibition caused by medium acidification

Microalgae, Botryococcus braunii in particular, have received increasing interest owing to their potential as biofuel sources. Although the fertilizer components present in wastewater are useful in reducing the cost of commercial production of microalgae, the ammonium nitrogen (NH4+-N) acidifies the medium and may inhibit the growth of B. braunii. In this study, we aimed to investigate the effectiveness of calcium carbonate in preventing the growth inhibition of B. braunii by suppressing pH decrease caused by NH4+-N. Four types of modified Chu13 media were prepared: a control, one with NH4+-N, one with calcium carbonate, and one with calcium carbonate and NH4+-N. Then, the pH, NH4+-N concentration, B. braunii growth, and hydrocarbon content were measured. We found that in the NH4+-N treatment without calcium carbonate, the pH decreased to approximately 4, and there was almost no algal growth even after 20 days. In contrast, there were no differences in the growth rate and medium pH (7–8) between the treatment with calcium carbonate and the control medium. In addition, calcium ions were leached into the medium with calcium carbonate as the culture progressed, confirming the effectiveness of calcium carbonate in maintaining a constant pH and thus preventing growth inhibition. As such, the addition of calcium carbonate effectively prevents B. braunii growth inhibition by suppressing pH decrease and is more cost-effective than aggressive pH adjustment with alkali or acid or by adding buffer solutions into the medium. This simple and inexpensive method can be used for the removal of ammonia from wastewater.

Continue reading ‘Calcium carbonate prevents Botryococcus braunii growth inhibition caused by medium acidification’

Increasing river alkalinity slows ocean acidification in the northern Gulf of Mexico

Ocean acidification (OA) progression is affected by multiple factors, such as ocean warming, biological production, and runoff. Here we used an ocean-biogeochemical model to assess the impact of river runoff and climate variability on the spatiotemporal patterns of OA in the Gulf of Mexico (GoM) during 1981-2014. The model showed the expected pH and aragonite saturation state (ΩAr) decline, due to the increase in anthropogenic carbon, with trends close to values reported for the Subtropical North Atlantic. However, significant departures from the basin-averaged pattern were obtained in part of the northern GoM shelf, where pH and ΩAr increased. Model sensitivity analyses showed that OA progression was counteracted by enhanced alkalinity from the Mississippi-Atchafalaya River System. Our findings highlight that river alkalinity is a key driver of carbon system variability in river-dominated ocean margins and emphasize the need to quantify riverine chemistry to properly assess acidification in coastal waters.

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Raising ambition at COP26 to deliver SDG14.3: to minimize and address the impacts of ocean acidification

Date: 8 November 2021

Time: 9:00am – 10:00am BST

Location: Commonwealth Pavilion, Blue Zone, Glasgow

More information to follow

Anthropogenic carbon dioxide emissions are the direct and main cause of ocean acidification, thus directly linking the achievement of SDG14.3 to the UNFCCC process. The most effective means for humanity to implement SDG14.3 is to stimulate much greater ambition and commitment to curtail anthropogenic GHG emissions at the UNFCCC’s COP26 in Glasgow.

However, ocean acidification also requires increased investments from all stakeholders in both the SDG and UNFCCC processes to improve the measure of its global progression and develop coastal information that support national response. If you can’t measure it, you can’t manage it. Measuring the global advance of ocean acidification and assessing its unique local impacts requires international collaboration, strategic knowledge building and national/regional action plans supported by financial investment.

This event brings together major world policy and scientific leaders in order to increase ambition, cooperation and investment to minimize and address the impacts of ocean acidification and further support integration across climate and ocean targets.

Hear from:

  • Dr. Vladimir Ryabinin, Executive Secretary of the Intergovernmental Oceanographic Commission and Assistant Director General of UNESCO
  • Ambassador Peter Thomson, UN SGD Special Envoy for the Ocean
  • Government Ministries, Ocean Experts and Civil Society

Co-Hosted:

  • Plymouth Marine Laboratory,
  • International Alliance to Combat Ocean Acidification and
  • IOC- UNESCO

In partnership with:

  • IAEA Ocean Acidification International Coordination Center (OA-ICC),
  • Global Ocean Acidification- Observing Network (GOA-ON) and
  • The Ocean Foundation
Continue reading ‘Raising ambition at COP26 to deliver SDG14.3: to minimize and address the impacts of ocean acidification’

From source to synthesis – improving flow of ocean carbon data (text & video)

OA Week 2021, From source to synthesis – improving flow of ocean carbon data

Dr. Helen Findlay, Plymouth Marine Laboratory, UK

Ms. Kirsten Isensee, Intergovernmental Oceanographic Commission of UNESCO, France

Mr. Benjamin Pfeil, University of Bergen, Norway

Dr. Katherina Schoo, Intergovernmental Oceanographic Commission of UNESCO, France

Description:

As data generating scientists, we have to find suitable data archives that are coherent with legal obligations of funders and that make it practical for access and visibility. In addition, data should be fit for purpose for synthesis products/reports in order to achieve greatest impact. The ocean acidification data landscape is a complex mix of data repositories, with varying audiences, purposes, meta and data requirements, as well as quality classifications and control mechanisms. Key to facilitating ocean acidification relevant data flow is communication among data producers, data managers and data users, addressing challenges and bringing together the community to find the best solutions. This discussion session of the OA week aims to continue ongoing and initiate new discussions around the following topics: 1. What are the current obstacles/challenges with respect to ocean acidification data flow in your region, your field of research? 2. Who should be taking part in ocean acidification data flow discussions – identification of main stakeholders? How can we improve data flow to meet the commitments for UN SDG 14.3.1, requirements of the funders and the wider benefits for our science and stakeholders that this unique opportunity brings in giving everyone access to datasets of known quality?

Ocean Acidification Week 2021 was sponsored by the following organizations:

(1) GOA-ON, the Global Ocean Acidification Observing Network,

(2) NOAA, the United States National Oceanic & Atmospheric Administration,

(3) IAEA OA-ICC, the International Atomic Energy Agency – Ocean Acidification International Coordination Centre, and

(4) IOC-UNESCO – the Intergovernmental Oceanographic Commission of the United Nations Educational, Scientific and Cultural Organization

For more information, please visit www.goa-on.org.

Continue reading ‘From source to synthesis – improving flow of ocean carbon data (text & video)’

Advancing the Ocean Acidification Information Exchange OAIE (text & video)

OA Week 2021, Advancing the Ocean Acidification Information Exchange

Ms. Julianna Mullen, NERACOOS, USA

Description:

The Ocean Acidification Information Exchange (OAIE) is an online members-only forum dedicated to catalyzing response to ocean and coastal acidification through collaboration. The platform’s tools are designed to make three major activities as simple as possible: sharing information, facilitating person-to-person connections, and keeping information organized and searchable. Online “communities of practice” like the OAIE are increasingly popular with professionals working toward shared outcomes in part because they’re proven to be effective at accelerating discovery, and they can remove many barriers to participation associated with diverse geographic involvement. However, while the OAIE and others are positioned solely as professional environments built on a straightforward calculus of ask and answer, the psychology of community—the emotional reactions/responses of people sharing a space—is inextricably linked to the success of the collective and individual. Considering the OAIE’s steady growth and everincreasing diversity, plus the rising popularity of professional communities of practice in general, we will discuss what additional barriers to participation remain (technological and humanistic), how the OAIE and other communities can advance equitable access to resources, and how we as individuals interact with and benefit from community, especially through the lens of the pandemic.

Ocean Acidification Week 2021 was sponsored by the following organizations:

(1) GOA-ON, the Global Ocean Acidification Observing Network,

(2) NOAA, the United States National Oceanic & Atmospheric Administration,

(3) IAEA OA-ICC, the International Atomic Energy Agency – Ocean Acidification International Coordination Centre, and

(4) IOC-UNESCO – the Intergovernmental Oceanographic Commission of the United Nations Educational, Scientific and Cultural Organization

For more information, please visit www.goa-on.org.

Continue reading ‘Advancing the Ocean Acidification Information Exchange OAIE (text & video)’

Seagrass restoration study shows rapid recovery of ecosystem functions

Restored plots of eelgrass in Elkhorn Slough expanded rapidly, providing improved habitat for fish and invertebrates and other benefits of a healthy ecosystem

As the dominant seagrass species on the U.S. West Coast, eelgrass supports a wide range of ecosystem services and functions, making its preservation and restoration a top priority for the region. Eelgrass restoration has a spotty record of success, however, and studies of restoration sites have rarely assessed the full range of ecosystem functions.

In a new study published October 6 in Ecological Applications, researchers demonstrated that eelgrass restoration efforts can lead to rapid expansion of restored plots and recovery of ecosystem functions.

Eelgrass meadow
Eelgrass meadows sustain critical ecosystem functions ranging from coastal protection and sediment stabilization to providing food and shelter for many species of fish and invertebrates.

The study involved small-scale experimental seagrass restoration efforts in Elkhorn Slough on the Central Coast of California. Researchers transplanted 2,340 shoots of eelgrass from healthy meadows into 117 small plots, and evaluated their success relative to areas without vegetation and natural eelgrass meadows.

The benefits of eelgrass meadows range from coastal protection and sediment stabilization to providing food and shelter for many species of fish and invertebrates. Eelgrass meadows provide crucial nursery habitat for many commercially important species, such as Dungeness crab, California halibut, and Pacific herring, whose juveniles find protection within the dense canopy. By slowing water flow and attenuating waves, eelgrass can act as a storm buffer and can protect developed coastlines from storm surges. Eelgrass meadows also counteract ocean acidification by absorbing carbon dioxide from seawater.

“Seagrass provides a whole suite of ecosystem services that we rely on, including all the recreational uses by folks like birders, kayakers, fishers, and others,” Beheshti said.

She noted that the California Ocean Protection Council’s Strategic Plan to Protect California’s Coast and Ocean includes a target to preserve the existing, known 15,000 acres of seagrass beds and create an additional 1,000 acres by 2025. In addition, she said, NOAA’s National Marine Fisheries Service is updating its California Eelgrass Mitigation Policy, which currently calls for “no net loss of eelgrass habitat function” but does not require mitigation projects to assess habitat function.

Continue reading ‘Seagrass restoration study shows rapid recovery of ecosystem functions’

Rapid enhancement of multiple ecosystem services following the restoration of a coastal foundation species

The global decline of marine foundation species (kelp forests, mangroves, salt marshes, and seagrasses) has contributed to the degradation of the coastal zone and threatens the loss of critical ecosystem services and functions. Restoration of marine foundation species has had variable success, especially for seagrasses, where a majority of restoration efforts have failed. While most seagrass restorations track structural attributes over time, rarely do restorations assess the suite of ecological functions that may be affected by restoration. Here we report on the results of two small-scale experimental seagrass restoration efforts in a central California estuary where we transplanted 117 0.25-m2 plots (2,340 shoots) of the seagrass species Zostera marina. We quantified restoration success relative to persistent reference beds, and in comparison to unrestored, unvegetated areas. Within three years, our restored plots expanded ˜8,500%, from a total initial area of 29 to 2,513 m2. The restored beds rapidly began to resemble the reference beds in (1) seagrass structural attributes (canopy height, shoot density, biomass), (2) ecological functions (macrofaunal species richness and abundance, epifaunal species richness, nursery function), and (3) biogeochemical functions (modulation of water quality). We also developed a multifunctionality index to assess cumulative functional performance, which revealed restored plots are intermediate between reference and unvegetated habitats, illustrating how rapidly multiple functions recovered over a short time period. Our comprehensive study is one of few published studies to quantify how seagrass restoration can enhance both biological and biogeochemical functions. Our study serves as a model for quantifying ecosystem services associated with the restoration of a foundation species and demonstrates the potential for rapid functional recovery that can be achieved through targeted restoration of fast-growing foundation species under suitable conditions.

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A monthly surface pCO2 product for the California Current Large Marine Ecosystem

To calculate the direction and rate of carbon dioxide gas (CO2) exchange between the ocean and atmosphere, it is critical to know the partial pressure of CO2 in surface seawater (pCO2(sw)). Over the last decade, a variety of data products of global monthly pCO2(sw) have been produced, primarily for the open ocean on 1° latitude by 1° longitude grids. More recently, monthly products of pCO2(sw) that are more finely spatially resolved in the coastal ocean have been made available. A remaining challenge in the development of pCO2(sw) products is the robust characterization of seasonal variability, especially in nearshore coastal environments. Here we present a monthly data product of pCO2(sw) at 0.25° latitude by 0.25° longitude resolution in the Northeast Pacific Ocean, centered around the California Current System (CCS). The data product (RFR-CCS; Sharp et al., 2021; https://doi.org/10.5281/zenodo.5523389) was created using the most recent (2021) version of the Surface Ocean CO2 Atlas (Bakker et al., 2016) from which pCO2(sw) observations were extracted and fit against a variety of satellite- and model-derived surface variables using a random forest regression (RFR) model. We validate RFR-CCS in multiple ways, including direct comparisons with observations from moored autonomous surface platforms, and find that the data product effectively captures seasonal pCO2(sw) cycles at nearshore mooring sites. This result is notable because alternative global products for the coastal ocean do not capture local variability effectively in this region. We briefly review the physical and biological processes — acting across a variety of spatial and temporal scales — that are responsible for the latitudinal and nearshore-to-offshore pCO2(sw) gradients seen in RFR-CCS reconstructions of pCO2(sw).

Continue reading ‘A monthly surface pCO2 product for the California Current Large Marine Ecosystem’

Emiliania huxleyi biometry and calcification response to the Indian sector of the Southern Ocean environmental gradients

Highlights

  • E. huxleyi morphotypes morphological variations in the SO
  • E. huxleyi extracellular overcalcification prominent in high latitude SO
  • E. huxleyi overcalcified coccosphers show extracellular Ca + Mg precipitation.
  • E. huxleyi may pre-adapted to changing carbonate chemistry.

Abstract

An increase in the atmospheric pCO2 and temperature is expected to reduce ocean CO32− concentration, make oceans warmer and alter ocean circulation patterns. This will also affect the production and biogeographic distribution of marine calcifying organisms including coccolithophores. The lowering of oceanic CO32− is expected to interfere with the coccolithophore calcification process and cause malformation of coccoliths, whereas changes in the oceanic temperature and circulation patterns may shift their biogeographic boundaries. In this study, we have investigated Emiliania huxleyi coccolith and coccosphere size response to the wide-ranging physico-chemical conditions of the Indian sector of the Southern Ocean between latitudes 38oS and 58oS during the austral summer of 2010 (January–February). This study helps to understand the response of E. huxleyi coccolith/coccosphere morphometry and mass changes to the fluctuating temperature, salinity, CO32−, pCO2, and nutrient values. Our results show that in the Indian sector of the Southern Ocean, E. huxleyi coccoliths are larger and coccospheres are smaller in the Subtropical Zone (STZ). In contrast, coccoliths size is smaller and coccospheres size is larger in the Subantarctic Zone (SAZ), which is due to the decrease in Sea Surface Temperature, Sea Surface Salinity and increase in nutrient concentrations. In the Indian sector of the Southern Ocean, E. huxleyi shows a north-to-south morphotype shift from the heavily calcified ‘Group A’ (E. huxleyi morphotype A) to the weakly calcified ‘Group B’ (E. huxleyi morphotypes B/C, C) forms. We demonstrate that although weakly calcified E. huxleyi morphotypes (morphotypes B/C and C) comprise less mass than that of the E. huxleyi morphotype A, due to the large-sized coccospheres and numerous coccoliths per coccosphere, ‘Group B’ coccospheres precipitate large amount of CaCO3 in the SAZ compared to ‘Group A’ coccospheres located in the STZ. We have documented the presence of large E. huxleyi overcalcified coccospheres with large-sized coccoliths in the southernmost cold, high pCO2, and nutrient-rich waters which show extracellular calcite precipitation. The energy dispersive spectrometry analysis indicates the presence of a large amount of Mg in the overcalcified E. huxleyi specimens. We suspect that E. huxleyi in the colder nutrient-rich waters, with future projected changes in the carbonate chemistry, may adapt to low pH, high pCO2 conditions through extracellular Ca and Mg mineralization.

Continue reading ‘Emiliania huxleyi biometry and calcification response to the Indian sector of the Southern Ocean environmental gradients’

Molecular basis of ocean acidification sensitivity and adaptation in Mytilus galloprovincialis

One challenge in global change biology is to identify the mechanisms underpinning physiological sensitivities to environmental change and to predict their potential to adapt to future conditions. Using ocean acidification as the representative stressor, molecular pathways associated with abnormal larval development of a globally distributed marine mussel are identified. The targeted developmental stage was the trochophore stage, which is, for a few hours, pH sensitive and is the main driver of developmental success. RNA sequencing and in situ RNA hybridization were used to identify processes associated with abnormal development, and DNA sequencing was used to identify which processes evolve when larvae are exposed to low pH for the full duration of their larval stage. Trochophores exposed to low pH exhibited 43 differentially expressed genes. Thirteen genes, none of which have previously been identified in mussel trochophores, including three unknown genes, were expressed in the shell field. Gene annotation and in situ hybridization point to two core processes associated with the response to low pH: development of the trochophore shell field and the cellular stress response. Encompassing both of these processes, five genes demonstrated changes in allele frequency that are indicative of rapid adaptation. Thus, genes underpinning the most pH-sensitive developmental processes also exhibit scope to adapt via genetic variation currently maintained in the mussel population. These results provide evidence that protecting existing genetic diversity is a critical management action to maximize the potential for rapid adaptation under a changing environment.

Continue reading ‘Molecular basis of ocean acidification sensitivity and adaptation in Mytilus galloprovincialis’

PhD opportunity: autonomous technologies and the marine carbon cycle: impacts of coastal processes on ocean acidification and blue carbon (ref: 4294)

Deadline application: 10 January 2022, 4:00pm GMT

Interviews period: 28 February – 4 March 2022

Location: Streatham Campus, University of Exeter, Exeter, Devon.

Apply now

This project is one of a number that are in competition for funding from the NERC Great Western Four+ Doctoral Training Partnership (GW4+ DTP).  The GW4+ DTP consists of the Great Western Four alliance of the University of Bath, University of Bristol, Cardiff University and the University of Exeter plus five Research Organisation partners:  British Antarctic Survey, British Geological Survey, Centre for Ecology and Hydrology,  the Natural History Museum and Plymouth Marine Laboratory.  The partnership aims to provide a broad training in earth and environmental sciences, designed to train tomorrow’s leaders in earth and environmental science. For further details about the programme please see http://nercgw4plus.ac.uk/

For eligible successful applicants, the studentships comprises:

  • An stipend for 3.5 years (currently £15,609 p.a. for 2022/23) in line with UK Research and Innovation rates
  • Payment of university tuition fees;
  • A research budget of £11,000 for an international conference, lab, field and research expenses;
  • A training budget of £3,250 for specialist training courses and expenses

Lead Supervisor

Dr Helen Findlay – Plymouth Marine Laboratory

Additional Supervisors

Dr Ceri Lewis – Biosciences, University of Exeter

Dr Tom Bell – Plymouth Marine Laboratory

Dr Mingxi Yang – Plymouth Marine Laboratory

Project Background:

Recent environmental and climate initiatives such as ‘habitat restoration’ and ‘Blue Carbon’ aim to increase local biodiversity, support carbon removal from the atmosphere, and alleviate the impacts of stressors such as ocean acidification and deoxygenation. However, the coastal environment is very dynamic, with a multitude of drivers that can impact the chemistry of CO2 and related compounds in seawater (together termed carbonates). It is this carbonate chemistry that ultimately alters the seawater’s ability to take up CO2 from the atmosphere, impacts biological processes such as respiration and photosynthesis, and determines the sensitivity of the system to processes such as ocean acidification. These coastal dynamics are still not well understood or even captured by the long-term, low frequency observations that are currently used for monitoring ocean acidification and other ocean changes. This project will take advantage of a suite of new autonomous vehicles and technologies, together with traditional discrete monitoring, to better characterise the near shore variations in carbonate chemistry, particularly with respect to ocean acidity (pH) and CO2.

Project Aims and Methods:

This project will take advantage of PML’s new fleet of autonomous marine platforms to make exciting novel observations of seawater CO2 and pH alongside air-sea CO2 fluxes with unprecedented spatial and temporal detail. The self-propelled surface (Autonaut) and subsurface (Ecosubs) vehicles are equipped with a range of sensors to measure near surface seawater salinity, temperature, pH and CO2. Air-sea CO2 exchange and pH observations on the L4 moored buoy (part of PML’s Western Channel Observatory) and discrete sampling of dissolved inorganic carbon and total alkalinity will be used to constrain the wider carbonate system. These measurements will facilitate a comprehensive understanding of the drivers of the carbonate system over a large range of scales (e.g. seconds to seasons in time, cms to many kms in space) and environmental conditions (e.g. high winds, waves, different tidal phases).

The student will also be expected to focus on some specific and important habitats, such as seagrass meadows (which are being re-established in Plymouth Sound through the Life ReMEDIES project https://saveourseabed.co.uk/wp-content/uploads/2021/06/Natural-Capital_Plymouth-Sound-and-Estuaries.pdf), kelp forests, and mussel farms. The carbon ‘footprint’ of these habitats will be evaluated by assessing their impact on air-sea CO2 flux and ocean acidification, as well as the biological influence on the coastal marine carbon. The student will synthesise the results to evaluate the implication for coastal carbon uptake, ocean acidification, mitigation, and adaptation.

Continue reading ‘PhD opportunity: autonomous technologies and the marine carbon cycle: impacts of coastal processes on ocean acidification and blue carbon (ref: 4294)’

Carbonate chemistry and calcifying plankton in Scottish coastal waters (text & video)

OA Week 2021, Northeast Atlantic Hub Session

Dr. Pablo León Díaz, Marine Scotland Science, UK

Description:

Ocean acidification (OA) is likely to have a significant impact on calcifying plankton. This group plays a key role in the ocean food webs and global biogeochemical cycles and includes larvae of species of commercial importance for aquaculture and fishery industries (e.g. bivalves). However field studies on carbonate chemistry and calcifying plankton are scarce.

Operated by Marine Scotland Science, the Scottish Coastal Observatory (SCObs; http://dx.doi.org/10.7489/1881-1) monitoring site at Stonehaven is providing baseline information about the seasonality and interannual variability of carbonate chemistry as well as the plankton community in Scottish waters. Three years of monthly samples were analysed using Scanning Electron Microscopy (SEM) to investigate the relationship between carbonate chemistry parameters and calcifying groups at Stonehaven, including coccolithophores, pelagic gastropods and the planktonic larvae of benthic bivalve species. SEM analyses revealed evidence of shell dissolution in all analysed species during the study period despite the seawater being supersaturated with respect to aragonite, with the most severe damaged observed during periods of decreasing aragonite saturation. These results suggest that seasonal and short-term changes in carbonate chemistry might affect the shell integrity of plankton calcifiers, also indicating that dissolution may appear under higher saturation values than previously assumed. This work also highlights the value of sustained observations to distinguish OA changes from natural variability and to assess the potential impacts of OA on marine ecosystems.

Ocean Acidification Week 2021 was sponsored by the following organizations:

(1) GOA-ON, the Global Ocean Acidification Observing Network,

(2) NOAA, the United States National Oceanic & Atmospheric Administration,

(3) IAEA OA-ICC, the International Atomic Energy Agency – Ocean Acidification International Coordination Centre, and

(4) IOC-UNESCO – the Intergovernmental Oceanographic Commission of the United Nations Educational, Scientific and Cultural Organization

For more information, please visit www.goa-on.org

Continue reading ‘Carbonate chemistry and calcifying plankton in Scottish coastal waters (text & video)’

Marine observations of carbonate chemistry variability and OA state in Northwest Africa waters (text & video)

OA Week 2021, Africa Hub Session

Dr. Mohammed Idrissi, National Institute of Fisheries Research, Morocco

Description:

The Canary Current Large Marine Ecosystem (CCLME) region supply very significant local and international fish resources, based largely on small pelagic fish and artisanal fisheries. Especially on the North West Africa Atlantic Sea, the fishery market contribute to economy of the region bordering this sea and provide an important food and employment to coastal communities. In 2017, the 30-year long EAF Nansen Program (FAO and Norway), began with studies on ocean acidification along the CCLME region. Here, we show the first results ocean acidification state from this new research theme focusing on the North West Africa waters (from Morocco (35°N) to Senegal (12°N). Between May 2017 and December 2019, samples were measured, on this region, onboard the R/V Dr. Fridtjof Nansen for total alkalinity and pH using potentiometric titration and spectrophotometric pH measurements, respectively. The other parameters describing the carbonate chemistry and ocean acidification state were derived from AT and pH, using the CO2SYS calculation program. The survey performed at twenty seven sections perpendicular from the coast (the mesopelagic transect included) with a total of 110 stations in the full water column. We found large variability along the coast, connected to salinity changes, primary production, temperature and biological processes.

Ocean Acidification Week 2021 was sponsored by the following organizations:

(1) GOA-ON, the Global Ocean Acidification Observing Network,

(2) NOAA, the United States National Oceanic & Atmospheric Administration,

(3) IAEA OA-ICC, the International Atomic Energy Agency – Ocean Acidification International Coordination Centre, and

(4) IOC-UNESCO – the Intergovernmental Oceanographic Commission of the United Nations Educational, Scientific and Cultural Organization

For more information, please visit www.goa-on.org

Continue reading ‘Marine observations of carbonate chemistry variability and OA state in Northwest Africa waters (text & video)’

Marine Scotland: celebrating 25 years of environmental monitoring

Temora by Adrian Weetman Crown Copyright

The Scottish Coastal Observatory (SCObs) is celebrating its 25th year of monitoring Scottish coastal seas.

Operated by the Marine Scotland directorate of the Scottish Government, SCObs samples temperature, salt content (salinity), chemistry (nutrients, ocean acidification), microscopic plants (algal pigments, phytoplankton) and animals (zooplankton) weekly around the Scottish coast.

SCObs data helps colleagues monitor and record the long term changes in our coastal waters and how these vary regionally around the Scottish coast. This is critical for us to understand how climate change is impacting our marine ecosystem and the plants and animals that live there. SCObs data provides baseline information that will help society adapt in the future to support the marine environment and the industries that depend on it. This is part of the Scottish Government’s work to tackle the twin crises of climate change and biodiversity loss.

The complete SCObs dataset, along with a companion report explaining the dataset and how to use it, is available and fully searchable on the Marine Scotland Monitoring Data page. We encourage everyone with an interest in the marine environment, including professional scientists, policymakers, students and concerned citizens to use these resources to find out more about the environmental conditions around Scotland’s coasts.

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Ocean acidity data affirm predictions of changes to El Niño conditions

Fishing boat.

Score one for a key climate change prediction.

A multi-institutional research team led by Yale and the University of St. Andrews has confirmed a major finding of climate models regarding changes that may occur to Pacific Ocean currents — including those that drive El Niño events — with just a few degrees of global warming.

El Niño affects weather, food security, economic productivity, and public safety for much of the planet. But there is ongoing debate as to how well climate models can replicate and predict past and future climate conditions in the tropics.

The new findings, published in the journal Nature, reflect the increased potential of climate models for predicting complex environmental dynamics. The findings also establish ocean acidity as an essential variable in climate modeling.

“Accurately capturing ocean dynamics in the equatorial Pacific in global climate models is crucial for predicting regional climate in the warmer decades to come,” said lead author Madison Shankle, a former Yale researcher who is now at the University of St. Andrews in Scotland.

Over the past decade, Alexey Fedorov, a professor of ocean and atmospheric sciences in Yale’s Faculty of Arts and Sciences (FAS), has conducted groundbreaking research on ocean dynamics around the world, including El Niño events — the warm phase of the El Niño Southern Oscillation that features unusually warm water in the Pacific. Fedorov and his research group conducted 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 a future, warmer world.

But over the years, some of Fedorov’s Yale colleagues — including climate scientists Pincelli HullNoah Planavsky, and the late Mark Pagani — wondered how consistent different ancient temperature data are and whether climate model simulations were accurately capturing the past climate state.

“We decided to test model predictions of major changes to the winds and currents driving El Niño by measuring something else, rather than temperature,” said Hull, assistant professor of Earth and Planetary Sciences in FAS and principal investigator for the new study. “We measured ocean acidity instead.”

Continue reading ‘Ocean acidity data affirm predictions of changes to El Niño conditions’

Pliocene decoupling of equatorial Pacific temperature and pH gradients

Ocean dynamics in the equatorial Pacific drive tropical climate patterns that affect marine and terrestrial ecosystems worldwide. How this region will respond to global warming has profound implications for global climate, economic stability and ecosystem health. As a result, numerous studies have investigated equatorial Pacific dynamics during the Pliocene (5.3–2.6 million years ago) and late Miocene (around 6 million years ago) as an analogue for the future behaviour of the region under global warming1,2,3,4,5,6,7,8,9,10,11,12. Palaeoceanographic records from this time present an apparent paradox with proxy evidence of a reduced east–west sea surface temperature gradient along the equatorial Pacific1,3,7,8indicative of reduced wind-driven upwelling—conflicting with evidence of enhanced biological productivity in the east Pacific13,14,15 that typically results from stronger upwelling. Here we reconcile these observations by providing new evidence for a radically different-from-modern circulation regime in the early Pliocene/late Miocene16 that results in older, more acidic and more nutrient-rich water reaching the equatorial Pacific. These results provide a mechanism for enhanced productivity in the early Pliocene/late Miocene east Pacific even in the presence of weaker wind-driven upwelling. Our findings shed new light on equatorial Pacific dynamics and help to constrain the potential changes they will undergo in the near future, given that the Earth is expected to reach Pliocene-like levels of warming in the next century.

Continue reading ‘Pliocene decoupling of equatorial Pacific temperature and pH gradients’

Distribution and abundances of planktic foraminifera and shelled pteropods during the polar night in the sea-ice covered Northern Barents Sea

Planktic foraminfera and shelled pteropods are important calcifying groups of zooplankton in all oceans. Their calcium carbonate shells are sensitive to changes in ocean carbonate chemistry predisposing them as an important indicator of ocean acidification. Moreover, planktic foraminfera and shelled pteropods contribute significantly to food webs and vertical flux of calcium carbonate in polar pelagic ecosystems. Here we provide, for the first time, information on the under-ice planktic foraminifera and shelled pteropod abundance, species composition and vertical distribution along a transect (82°–76°N) covering the Nansen Basin and the northern Barents Sea during the polar night in December 2019. The two groups of calcifiers were examined in different environments in the context of water masses, sea ice cover, and ocean chemistry (nutrients and carbonate system). The average abundance of planktic foraminifera under the sea-ice was low with the highest average abundance (2 ind. m–3) close to the sea-ice margin. The maximum abundances of planktic foraminifera were concentrated at 20–50 m depth (4 and 7 ind. m–3) in the Nansen Basin and at 80–100 m depth (13 ind. m–3) close to the sea-ice margin. The highest average abundance (13 ind. m–3) and the maximum abundance of pteropods (40 ind. m–3) were found in the surface Polar Water at 0–20 m depth with very low temperatures (–1.9 to –1°C), low salinity (<34.4) and relatively low aragonite saturation of 1.43–1.68. The lowest aragonite saturation (<1.3) was observed in the bottom water in the northern Barents Sea. The species distribution of these calcifiers reflected the water mass distribution with subpolar species at locations and depths influenced by warm and saline Atlantic Water, and polar species in very cold and less saline Polar Water. The population of planktic foraminifera was represented by adults and juveniles of the polar species Neogloboquadrina pachyderma and the subpolar species Turborotalita quinqueloba. The dominating polar pteropod species Limacina helicina was represented by the juvenile and veliger stages. This winter study offers a unique contribution to our understanding of the inter-seasonal variability of planktic foraminfera and shelled pteropods abundance, distribution and population size structure in the Arctic Ocean.

Continue reading ‘Distribution and abundances of planktic foraminifera and shelled pteropods during the polar night in the sea-ice covered Northern Barents Sea’

Nutrient alteration drives the impacts of seawater acidification on the bloom-forming dinoflagellate Karenia mikimotoi

Seawater acidification and nutrient alteration are two dominant environmental factors in coastal environments that influence the dynamics and succession of marine microalgae. However, the impacts of their combination have seldom been recorded. A simulated experimental system was set up to mimic the effects of elevated acidification on a bloom-forming dinoflagellate, Karenia mikimotoi, exposed to different nutrient conditions, and the possible mechanism was discussed. The results showed that acidification at different pH levels of 7.6 or 7.4 significantly influenced microalgal growth (p<0.05) compared with the control at pH 8.0. Mitochondria, the key sites of aerobic respiration and energy production, were impaired in a pH-dependent manner, and a simultaneous alteration of reactive oxygen species (ROS) production occurred. Cytochrome c oxidase (COX) and citrate synthase (CS), two mitochondrial metabolism-related enzymes, were actively induced with acidification exposure, suggesting the involvement of the mitochondrial pathway in coping with acidification. Moreover, different nutrient statuses indicated by various N:P ratios of 7:1 (N limitation) and 52:1 (P limitation) dramatically altered the impacts of acidification compared with those exposed to an N:P ratio of 17:1 (control), microalgal growth at pH 7.4 was obviously accelerated with the elevation of the nutrient ratio compared to that at pH 8.1 (p<0.05), and nutrient limitations seemed beneficial for growth in acidifying conditions. The production of alkaline phosphatase (AP) and acid phosphatase (AcP), an effective index indicating the microalgal growth status, significantly increased at the same time (p<0.05), which further supported this speculation. However, nitrate reductase (NR) was slightly inhibited. Hemolytic toxin production showed an obvious increase as the N:P ratio increased when exposed to acidification. Taken together, mitochondrial metabolism was suspected to be involved in the process of coping with acidification, and nutrient alterations, especially P limitation, could effectively alleviate the negative impacts induced by acidification. The obtained results might be a possible explanation for the competitive fitness of K. mikimotoi during bloom development.

Continue reading ‘Nutrient alteration drives the impacts of seawater acidification on the bloom-forming dinoflagellate Karenia mikimotoi’

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