Archive Page 155

Advancing science: IAEA supports young scientists at ocean acidification symposium

Published 20 September 2022 Web sites and blogs Closed
The IAEA has sponsored 18 early career scientists to attend the 5th International Symposium on the Ocean in a High CO2 World, Lima, 13–16 September 2022. (Photo: IAEA)

As part of its commitment to promote international collaboration, the IAEA highlighted the role nuclear and isotopic techniques can play in assessing the impacts of ocean acidification at the 5th International Symposium on the Ocean in a High CO2 World, held last week in Lima, Peru. In addition to delivering workshops and presentations, the IAEA sponsored the attendance of 18 early career scientists at the event.

Ocean acidification is one of the greatest threats of our time to marine organisms, ecosystems and resources. It occurs when carbon dioxide (CO2) is released into the atmosphere by human activities and is absorbed by the ocean: the ocean takes up about a quarter of all human-made CO2 emitted to the atmosphere each year. The resulting change in the acidity of seawater can have lasting, detrimental effects on fragile marine ecosystems. Impacts of ocean acidification can also have drastic socio-economic consequences in countries that are dependent on marine resources.

“Ocean acidification is now a reality whose economic consequences are clearly noticeable and whose effects could be devastating in the long term for many sectors, starting with the farming and harvesting of many shellfish and crustaceans that are already severely impacted,” said Prince Albert II of Monaco, in his opening remarks at the symposium. “We know that these sectors represent vital sources of income and food for millions of people.”

Studying the impact of ocean acidification is a high priority for the IAEA. The Ocean Acidification International Coordination Centre (OA-ICC) at the IAEA Marine Environment Laboratories in Monaco, works to communicate, promote and facilitate international activities on ocean acidification in three categories: science, capacity building and communication. It coordinates communication among experts and facilitates outreach to stakeholders, ranging from scientists and policymakers to educators, the media and the general public.

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Emisión en directo de symposium high CO2 – Lima (video) (in Spanish)

Published 20 September 2022 Presentations , Resources Closed
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As coral reefs face threats, UB scientists study the future of soft corals

Published 20 September 2022 Web sites and blogs Closed
UB coral researchers Mary Alice Coffroth and Howard Lasker. Photo: Douglas Levere

This summer, coral researchers from around the world gathered to share their latest findings at a conference devoted to reef science, conservation and management.

One question that looms large in the field: As warming waters, ocean acidification and other pressures threaten corals, what will reefs look like in years to come?

“Much of the conference was focused on the future of coral reefs,” says UB scientist Howard Lasker, who attended the 15th International Coral Reef Symposium in July in Bremen, Germany, with fellow UB coral scientist Mary Alice Coffroth. Both are research professors of geology in the College of Arts and Sciences.

“While it has been a consistent theme that we must reduce CO2 emissions, the focus of many of the papers has been the science behind approaches to facilitate the survival and recovery of reef corals,” Lasker adds.

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Ocean acidification research for sustainability: co-designing global action on local scales

Published 19 September 2022 Science Closed
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The global threat that ocean acidification poses to marine ecosystems has been recognized by the UN 2030 Agenda under Sustainable Development Goal, Target 14.3: to reduce ocean acidification. The Global Ocean Acidification Observing Network (GOA-ON) is a collaborative international network to detect and understand the drivers of ocean acidification in estuarine-coastal-open ocean environments, the resulting impacts on marine ecosystems, and to make the information available to optimize modelling studies. The Ocean Acidification Research for Sustainability (OARS) programme, endorsed by the 2021–2030 UN Decade of Ocean Science for Sustainable Development, will build on the work of GOA-ON through its seven Decade Action Outcomes. By employing a Theory of Change framework, and with the co-design of science in mind, OARS will develop an implementation plan for each Decade Action Outcome, which will identify the stakeholders and rights-holders, as well as the tools, means, and positive consequences required for their successful delivery. The organizational structure of GOA-ON, with nine regional hubs, will benefit OARS by providing a vital connection between local and global scales. GOA-ON regional hub case-studies illustrate how activities in the past and future, informed by global and regional priorities, support capacity building and the co-design of ocean acidification science.

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Vulnerability of exploited deep-sea demersal species to ocean warming, deoxygenation, and acidification

Published 19 September 2022 Science Closed
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Vulnerability of marine species to climate change (including ocean acidification, deoxygenation, and associated changes in food supply) depends on species’ ecological and biological characteristics. Most existing assessments focus on coastal species but systematic analysis of climate vulnerability for the deep sea is lacking. Here, we combine a fuzzy logic expert system with species biogeographical data to assess the risks of climate impacts to the population viability of 32 species of exploited demersal deep-sea species across the global ocean. Climatic hazards are projected to emerge from historical variabilities in all the recorded habitats of the studied species by the mid-twenty-first century. Species that are both at very high risk of climate impacts and highly vulnerable to fishing include Antarctic toothfish (Dissostichus mawsoni), rose fish (Sebastes norvegicus), roughhead grenadier (Macrourus berglax), Baird’s slickhead (Alepocephalus bairdii), cusk (Brosme brosme), and Portuguese dogfish (Centroscymnus coelepis). Most exploited deep-sea fishes are likely to be at higher risk of local, or even global, extinction than previously assessed because of their high vulnerability to both climate change and fishing. Spatially, a high concentration of deep-sea species that are climate vulnerable is predicted in the northern Atlantic Ocean and the Indo-Pacific region. Aligning carbon mitigation with improved fisheries management offers opportunities for overall risk reduction in the coming decades. Regional fisheries management organizations (RFMOs) have an obligation to incorporate climate change in their deliberations. In addition, deep-sea areas that are not currently managed by RFMOs should be included in existing or new international governance institutions or arrangements.

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A method for identifying sensitivity of marine benthic invertebrates to ocean acidification through a biological traits approach

Published 19 September 2022 Science Closed
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Ocean acidification poses a major threat to the structure and diversity of marine ecosystems. The marine seabed sustains important ecosystem functions, and so understanding the sensitivity to increased pCO2 within benthic invertebrates is critical for informing future management strategies. Here, we explore a traits-based approach for estimating the sensitivity of benthic taxa to ocean acidification, using data from the western area of the North Sea. We selected 56 taxa across 11 taxonomic groups representative of the various habitats found in the region. Biological traits considered sensitive to elevated pCO2 were identified from literature review, and the taxa were scored for each trait to produce a total relative sensitivity (TRS) index. We investigated differences in sensitivity between the taxa and across habitats and explored whether sensitivity was spatially aggregated. Our analyses indicated that benthic species are sensitive to acidification, with 51% of the taxa scoring in the top three TRS bands overall, and hot spots of sensitivity being more widely distributed across the region than corresponding “cold spots” (low sensitivity). The opportunities and limitations of the approach are discussed.

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Intergenerational effects of ocean acidification on reproductive traits of an estuarine copepod

Published 19 September 2022 Science Closed
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Graphical abstract

Copepods are an important part of the marine food web because of their high biomass productivity and nutrient turnover rate compared to other zooplankton in the marine ecosystem. Despite their great ecological role in the ocean, there is only limited information available on the consequences of ocean acidification (OA) induced by the future increase in CO2 on the planet. More specifically, there is almost no information about the impact of OA on the European copepod Calanipeda aquaedulcis Kritschagin, 1873. Therefore, the present investigation hypothesized that OA would not produce negative multigenerational effects on the survival and reproductive performance of this copepod species. Here we assessed, the multigenerational (F1 and F2) effect of OA on eight important reproductive traits (maturity, prosome length, fertility, egg release, hatching success, survival rate, reproductive performance, and the total number of adults per generation). For this study, C. aquaedulcis were collected from the Guadalquivir River (southwest of Spain) and were exposed to four different pH gradients (pH 8.1 as control and pH 7.5, 7.0, 6.5 as acidified conditions) to mimic the future seawater acidification scenarios. The survival rate from nauplius to adult, C. aquaedulcis was significantly reduced by pHs and across generations. Besides, results also indicated that there were marked effects on fertility, reflected by a significantly lower number of eggs per female in each generation. Similarly, hatching success also showed a decreasing pattern towards low pH, and importantly, F1 females had lower hatching success than F0 females. While a beneficial parental effect was detected in the offspring in response to OA, it was insufficient to offset the negative effects caused by it. The findings presented here appear to have ecological significance, as decreasing the reproductive performance of copepods may have a negative impact on the marine food web, as ichthyofaunal feeding and growth are heavily reliant on this component of the food web.

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Aquaculture Europe 22

Published 19 September 2022 Events Closed

Date: 27-30 September 2022

Location: Rimini, Italy

The issues of compatibility and mutual synergy between the users of marine, brackish and freshwater resources and their relationship with the quality of those ecosystems are central in promoting the sustainable development of the Blue economy and aquaculture.

Traditional and emerging Blue economy sectors, currently operating in the Adriatic, Mediterranean and water bodies throughout Europe, are expected to grow and expand over the next years and to sustainably contribute to food production, biofuel and clean energy.

Nevertheless, scientific literature provides clear evidence that, according to current trends and within 10 years, our coastal and marine environment will change for sea acidification and warming, sea-level rise and coastal erosion and all water bodies will be affected by flooding, eutrophication and pollution, with important effects on ecosystem services, fish and shellfish stocks and food security.

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Plenary 1. Wednesday, September 28 09:00 – Climate change and aquaculture

An overview of the short term scenarios of how climate changes will affect temperature, sea level, severe weather, flooding, erosion, acidification for the Med and Adriatic. Followed by specific aquaculture climate impacts and challenges – with case studies of iconic fish and shellfish species.

Speakers:

  • Nadia Pinardi, Departament of Physics and Astronomy, University of Bologna
  • Mariana Mata Lara, Geonardo Environmental Technologies

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Job opportunity: associate scientist, MPAs and climate change (job # 1789)

Published 19 September 2022 Jobs Closed

Location: Santa Barbara, CA, United States

To apply for this position please submit a resume and cover letter.

Application Deadline: September 30, 2022 (11:49 PM EST) 

Apply Now

Conservation International protects nature for the benefit of humanity. Through science, policy, fieldwork, and finance, we spotlight and secure the most important places in nature for the climate, biodiversity, and for people. With offices in 30 countries and projects in more than 100 countries, Conservation International partners with governments, companies, civil society, Indigenous peoples, and local communities to help people and nature thrive together.

POSITION SUMMARY

Science manager– Marine Protected Areas and Climate Change Community of Practice

Research scientist with an advanced degree in marine biology or related field to build a community of practice of MPA managers and stakeholders in an era of rapid climate change, with special emphasis on coordination, communications outreach, and contribution to research in MPA theory and practice.

Position Objective: Build a Community of Practice for MPA managers and planners dealing with climate change and contribute to climate change and marine conservation research. Disseminate cutting-edge research on MPA planning and management for resilience to climate change and connect ocean management stakeholders around the world.

The position addresses fundamental challenges associated with the need to build communities of practice for climate change in conservation communities dealing with ocean biodiversity conservation as ecosystems and species move in response to climate change (including ocean acidification). The position will implement and refine a strategy for building a community of practice in MPAs and climate change and conduct research on program thematic focal areas under the guidance of the lead scientist for CI’s MPAs and climate change initiative.

24-month appointment with the possibility for renewal.

RESPONSIBILITIES

  • Design and build a community of practice in MPAs and climate change (reserve managers, including diverse stakeholders).
  • Conduct research on Marine Protected Areas and climate change.
  • Coordinate outreach and communications efforts related to MPAs and climate change.
  • Lead climate assessments and site engagements to guide planning and management for climate-smart MPAs.
  • Contribute to marine climate change research team in focal regions, with the potential to lead research into possible climate change impacts on MPAs and planning/management solutions to the challenges identified.
  • Other duties as assigned by supervisor.

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Factors affecting the subsurface aragonite undersaturation layer in the Pacific Arctic region

Published 16 September 2022 Science Closed
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Highlights

  • Freshwater content and mixing of Pacific water with Atlantic water determined the boundaries of aragonite undersaturation.
  • The upper boundary deepened inside the Beaufort Gyre when anticyclonic circulation enhanced gyre intensity.
  • The lower boundary was significantly lifted following an Atlantic-origin cold saline water intrusion event in 2017.

Abstract

This study evaluated interannual variation in the subsurface aragonite undersaturation zone (ΩAr<1 layer) in the Pacific Arctic Ocean, using data from the 2016–2019 period. The upper boundary (DEPΩ<1UB) of the ΩAr<1 layer generally formed at a depth where the contribution of corrosive Pacific water was approximately 98 %. The intensity of the Beaufort Gyre associated with freshwater accumulation mainly determined interannual variation in DEPΩ<1UB, but the direction of its effect was opposite west and east of ~166°W. The lower boundary (DEPΩ<1LB) of the ΩAr<1 layer was generally found at a depth range where equal contributions of Pacific and Atlantic water were expected. An Atlantic-origin cold saline water intrusion event in 2017 caused by an anomalous atmospheric circulation pattern significantly lifted the DEPΩ<1LB, thus the thickness of the ΩAr<1 layer decreased.

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A transcriptomic analysis of phenotypic plasticity in Crassostrea virginica larvae under experimental acidification

Published 16 September 2022 Science Closed
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Graphical abstract

Ocean acidification (OA) is a major threat to marine calcifiers, and little is known regarding acclimation to OA in bivalves. This study combined physiological assays with next-generation sequencing to assess the potential for recovery from and acclimation to OA in the eastern oyster (Crassostrea virginica) and identify molecular mechanisms associated with resilience. In a reciprocal transplant experiment, larvae transplanted from elevated pCO2 (~1400 ppm) to ambient pCO2 (~350 ppm) demonstrated significantly lower mortality and larger size post-transplant than oysters remaining under elevated pCO2 and had similar mortality compared to those remaining in ambient conditions. The recovery after transplantation to ambient conditions demonstrates the ability for larvae to rebound and suggests phenotypic plasticity and acclimation. Transcriptomic analysis supported this hypothesis as genes were differentially regulated under OA stress. Transcriptomic profiles of transplanted and non-transplanted larvae terminating in the same final pCO2 converged, further supporting the idea that acclimation underlies resilience. The functions of differentially expressed genes included cell differentiation, development, biomineralization, ion exchange, and immunity. Results suggest acclimation as a mode of resilience to OA. In addition, the identification of genes associated with resilience can serve as a valuable resource for the aquaculture industry, as these could enable marker-assisted selection of OA-resilient stocks.

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Review predicts big climate change impact on some marine mammals

Published 16 September 2022 Newsletters and reports , Press releases Closed

A new DOC report predicts that climate change could have a major impact on some of New Zealand’s marine mammals.

Read the report

Co-authored by Jim Roberts, Anemone Consultants, and Hannah Hendriks, DOC’s Marine Technical Advisor, the research paper examines climate change in relation to marine mammals’ habitat, distribution, food sources and predators.

It looked at how specific climate change hazards, such as increasing sea temperatures, rising sea levels, changes in ocean circulation and effects on prey species, would impact marine mammals around New Zealand.

The report identifies changes in food supply as the biggest threat to marine mammals in New Zealand waters.  

“This is likely to impact populations including kekeno/New Zealand fur seal in the Westland region and blue whales foraging at the South Taranaki Bight,” says Hannah Hendriks.

“Māui dolphins also appear vulnerable, based on their location at the warm end of the species’ range and an apparent low availability of prey species.”

Projected changes to the New Zealand environment include sea surface temperatures rising more than 3oC, changes in atmospheric climate and oceanographic circulation, rising sea levels, and widespread ocean acidification.  

“As a result, it is possible species normally living in warmer subtropical waters like the dense-beaked whale, dwarf sperm whale, pan-tropical spotted dolphin, short-finned pilot whale and pygmy killer whale, will become more common around New Zealand, and potentially outcompeting some of the marine mammals we currently see,” says Hannah.

“Similarly, species that live in cooler subantarctic waters could become sparser around New Zealand as they move south.”

This review shows changes to the environment won’t be felt equally in all parts of New Zealand.

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Department of Conservation: The Papa Atawbai, 16 September 2022. Press release.

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UNESCO job opportunity: individual consultant to develop an integrated coral reef monitoring manual for MPA in Vietnam

Published 16 September 2022 Jobs Closed

Duty Station: Bangkok

Duration of contract: From 7 to 11 months

Application Deadline (Midnight Paris Time): 23-SEP-2022

Apply now

1. Background and Rationale

The United Nations has proclaimed a Decade of Ocean Science for Sustainable Development (2021-2030) to support efforts to reverse the cycle of decline in ocean health and gather ocean stakeholders worldwide behind a common framework that will ensure ocean science can fully support countries in creating improved conditions for sustainable development of the Ocean. The Ocean Decade calls for Decade Actions from diverse stakeholders.

The UNESCO/IOC Sub-Commission for the Western Pacific (WESTPAC) is the regional body of the Intergovernmental Oceanographic Commission (IOC/UNESCO) for the Western Pacific and its adjacent areas. Its mission is to advance ocean knowledge in order to assist Member States in the conservation and sustainable development of ocean, seas and marine resources. Meanwhile, The Sub-Commission WESTPAC also assists the IOC to coordinate regional engagement in the UN Ocean Decade.

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The Vietnam MPA network has been formed since 2010, following the Prime Minister Decree. Till present  a total of 12 MPAs have been established, with most of them focused on coral reefs habitats. Coral reef monitoring has been conducted in a number of MPAs in Vietnam, using indicators of ReefCheck and Line Intercept Transect (LIT) methods. Periodical data were provided to ReefCheck International database and used for periodical reports on coral reef status by the Global Coral Reef Monitoring Network (GCRMN). Monitoring data was also used to evaluate management effectiveness in some MPAs such as Nha Trang Bay, Cu lao Cham or National Parks (Con Dao, Phú Quoc). 

Given the fact that monitoring programs in the past mainly focused on ecological indicators, MPA authorities have no data and information to assess the MPA management effectiveness in supporting fisheries recruitment and tourist services. In addition, emerging issues such as ocean acidification, plastic and microplastic, have been generating negative impacts on coral reef, but have not been considered in any monitoring programs. Furthermore, recent monitoring seems not to be sufficient to record coral bleaching which occurred frequently and remain unpredicted. 

2. Key Duties and Responsibilities

Under the overall authority of the Director of the UNESCO Regional Bureau for the Asia and Pacific, and the direct supervision of the Head of the WESTPAC Office, the incumbent shall carry out desktop studies, field work, stakeholder consultation, and develop partnerships with relevant institutions, including:

a. Review monitoring techniques which were applied for coral reefs in the Western Pacific, and more specifically in Vietnam, including their socio-economic aspects;

b. Conduct site visits in at least 2 selected MPAs, analyze status in using coral reef resources for fisheries and tourism as well as monitoring requirements, identify appropriate methods for monitoring socio-economic indicators and emerging issues;

c. Contact (online) MPA authorities in Vietnam, analyze monitoring requirements, and identify their existing monitoring capacity;

d. Develop and publish an integrated coral reef monitoring manual for MPAs in Vietnam, taking into account the conventional monitoring methods and emerging requirements for understanding the impacts of ocean acidification, marine plastic debris, including their socio-economic aspects;

e. Conduct demonstration workshop (s) for MPAs in Vietnam, and assist in the establishment of needed monitoring capacity;

f. Prepare and produce various reports associated with the Specific Tasks outlined above;

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Workshop: ecosystem science & modeling

Published 16 September 2022 Events Closed

Date: 24 September 2022

Time: 2:00 – 3:30 pm

Location: Oso Bay Wetlands Preserve and Learning Center – 2446 N. Oso Parkway – Corpus Christi, Texas 78414

Registration

JOIN THE HARTE RESEARCH INSTITUTE AT THE OSO BAY WETLANDS PRESERVE FOR A WETLANDS WORKSHOP!

HRI’s Ecosystem Science & Modeling Lab investigates environmental changes in coastal and estuarine ecosystems due to climate change and human activities.  In this presentation and exercise, Dr. Xinping Hu will discuss ocean acidification and how it affects global marine species. 

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A summer with abalone and research

Published 16 September 2022 Web sites and blogs Closed
An image of the experimental set up for the dulce raised in different temperatures. Water comes in from the bottom and moves out through pipe at the top. This container has the smaller of the two abalone sizes.

Kordi Kokott is a biology student who recently graduated from the SRJC with an Associates in biology. She’s moving on to become a student at UC Davis to get her bachelor’s in biotechnology. She was an intern at the Bodega Marine Lab in the summer of 2022 and was mentored by Sara Boles.

This summer, I actually got to work on two different experiments – one where I helped to set up an experiment, and one where I analyzed data. The first experiment was a nutritional analysis – examining how dulce cultivated at different temperatures would affect the growth and health of two different ages of juvenile abalone. The other experiment I worked on was examining the transgenerational effects of ocean acidification on abalone. For this experiment, I came in as it was almost finished and simply did data analysis.

For the first experiment I helped to set it up, since the actual experiment would run much longer than my stay at the BML. Throughout the time that I spent setting up this experiment I learned a lot about the process behind the science. Making an experiment isn’t necessarily a straightforward process, where you simply have an idea and then execute it. Oftentimes, there are twists and turns along the way. We started out using one container, and then switched to another kind that would work better. We didn’t have the right size of mesh at first, so we had to go out and find some. Our small abalone kept dying, so we had to get a new shipment of them so that it wouldn’t present a confounding factor. All of this happened but still, the experiment went on, because we found ways to solve them. I was able to learn how essential the ability to be flexible and innovative is to science, and that kind of hands-on experience is priceless to a budding scientist.

For the second experiment – I had another unique experience: I processed data. Essentially, I examined abalone in photos that had been taken previously and found the area and length of their shell. I didn’t actually do much with this data – my mentor is the one that created figures and the one that did all the real work analyzing it. All I did was draw circles and lines on the screen with a computer mouse. It was boring, tedious, and time consuming – but it was also essential. Examining shell length and size of 495 abalone (yes, I counted) showed me something else about science – it might not always be exciting, but without the somewhat tedious parts, you never can reach any conclusions. 

Throughout my summer journey at the bodega marine lab, I got to see all sides of science and research. I got to do hands on work, see an experiment get started, and I got to hold an abalone (which was a pretty cool experience). Overall, my time at the BML was in a word, amazing. I feel like I really contributed to something, and my understanding of the scientific process is much broader than it used to be.

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Could a future ocean acidification scenario influence the photodegradation of microplastics?

Published 15 September 2022 Science Closed
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Microplastics (MPs) in the marine environment are subject to photodegradation, a process in which they easily get fragmented and leach potentially dangerous compounds. Ocean acidification (OA), owing to the enrichment of carbon dioxide (CO 2 ), is one of the main chemical changes occurring in the marine environment and may be a factor that influences photodegradation. This study aims to investigate the influence of OA on the photodegradation of three types of MPs: polypropylene (PP), expanded polystyrene (EPS), and ethylene-vinyl acetate (EVA). MPs were weathered by exposing them simultaneously for 8 hours to accelerated ultraviolet (UV) radiation and to three pH levels ( i.e. , 8.1, 7.8, and 7.5), which were achieved by injecting CO 2 into a simulated marine medium. The acidification system reproduced the current environmental conditions and those calculated for the future. As expected, the higher the partial pressure of CO2 , total inorganic carbon, bicarbonate ion, and CO2 , the more acidic the pH, and the opposite is true for carbonate ion. Structural changes were assessed by Fourier transform infrared spectroscopy, differential scanning calorimetry, gel permeation chromatography, and scanning electron microscopy. All weathered samples showed a higher degradation rate than the virgin samples. The MPs of PP and EVA presented the highest degradation rates, indicating the development of oxygen-containing functional groups and an increase in crystalline fraction. The oxidation state and crystallinity were higher in samples exposed to the lowest pH. There was no significant difference (p > 0.05) in the degradation rate of EPS samples. The results allow us to infer that an increase in OA predicted for the future could interfere with the photodegradation of some types of MP polymers, accelerating this process.

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Response of calcareous nannoplankton to the Paleocene–Eocene Thermal Maximum in the Paratethys seaway (Tarim Basin, West China)

Published 15 September 2022 Science Closed
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Highlights

  • A new, shallow marine Paleocene–Eocene Thermal Maximum (PETM) record was discovered in the eastern Tethys.
  • High-resolution calcareous nannofossil biostratigraphy across the PETM was established.
  • The PETM “excursion taxa” are marker species for identifying PETM record in the eastern Tethys.
  • Low pre- and syn-PETM carbonate contents were attributed to ocean acidification and terrestrial dilution.
  • Marine productivity increased during the PETM due to elevated nutrient input from continental weathering.

Abstract

The Paleocene-Eocene Thermal Maximum (PETM) was a rapid global warming occurred 56 million years ago and has been widely viewed as an ancient analogue to the ongoing warming driven by anthropogenic CO2 emissions. The complete and continuous Paleogene shallow marine strata well preserved and outcropped in the Tarim Basin, northwestern China are ideal to study the paleoenvironmental change of the Paratethys Seaway during the PETM. To date, no high-resolution calcareous nannofossil biostratigraphy has been performed for the PETM interval in the Tarim Basin. Outcrop samples taken from the Qimugen Formation in the Kuzigongsu section contain abundant, moderately well preserved calcareous nannofossils allows for the establishment of a high-resolution biostratigraphic framework. Overall, 73 species of calcareous nannofossils from 33 genera were observed, with the dominant species including Coccolithus pelagicus, various Toweius species, Pontosphaera exilis, and Micrantholithus flos. The five calcareous nannofossil datums allow for the recognization of nannofossil Zone NP6 through Zone NP10. The common occurrence of shallow-water taxa (Micrantholithus) throughout the section suggests a middle to outer neritic setting for depositional environment of the Kuzigongsu section. The stratigraphic distribution of “excursion taxa” (Coccolithus bownii, Discoaster araneus, D. acutus, Rhomboaster spp.) is consistent with the range of negative excursion in δ13Ccarb and δ18Ocarb, indicating that these excursion taxa are micropaleontological means for identifying the presence of the PETM in the Paratethys Seaway. During the PETM, the deteriorated preservation and extremely low abundance of nannofossils and near-zero wt% CaCO3 values suggest that ocean acidification occurred in the shallow water of the Paratethys Seaway. In addition, a significant increase in the species Neochiastozygus junctus, which is a high productivity indicator indicates increased surface ocean productivity. Higher primary productivity may be triggered by enhanced continental weathering delivering increased nutrient through river runoff.

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Effects of the ocean acidification on the functional structure of coral reef nematodes

Published 15 September 2022 Science Closed
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A mesocosm experiment was designed to study the effects of acidification on the phytal nematofauna of a coral reef. We hypothesized that phytal nematodes are responsive to different seawater acidification levels and that their assemblage structure and functional indicators (combination of maturity index and trophic diversity index) are useful to evaluate the effects of acidification. Artificial substrate units (ASU) were first colonized in a coral reef zone (Recife de Fora Municipal Marine Park, Porto Seguro, Bahia, Brazil) to obtain standardized assemblage samples. ASUs were transferred to laboratory and exposed to control and three levels of seawater acidification (pH reduced by 0.3, 0.6 and 0.9 units below field levels) and collected after 15 and 30 d. Contrary to our expectations that acidification may change the taxonomic structure of nematodes, while the functional structure may deviate from the expected under high levels of acidification, we found that univariate functional indicators of the community (index of trophic diversity and maturity index) did not show significant differences between the control and experimental treatments throughout the exposure period. It is probably because the frequent exposure of shallow-water nematodes to rather large environmental variations leads the faunal response to acidification to be complex and subtle. On the other hand, the density of the life-history strategy groups 3 and 4 and the structure of nematode assemblages were significantly affected by different pH levels throughout the exposure period. Both history strategy groups include all kinds of feeding groups. These results suggest that the impact of pH changes predicted by the years 2100 and 2300 may be strong enough to provide different traits or life-history strategies of nematodes to take advantage under changing conditions.

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Variable pH and subsequent change in pCO2 modulates the biofilm formation, synthesis of extracellular polymeric substances, and survivability of a marine bacterium Bacillus stercoris GST-03

Published 14 September 2022 Science Closed
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Biofilm-forming bacteria adhere to the substrates and engage in the nutrient cycling process. However, environmental conditions may interrupt the biofilm formation ability, which ultimately may affect various biogeochemical cycles. The present study reports the effect of varying pH and subsequent change in pCO2 on the survivability, biofilm formation, and synthesis of extracellular polymeric substances (EPS) of a biofilm-forming marine bacterium Bacillus stercoris GST-03 isolated from the Bhitarkanika mangrove ecosystem, Odisha, India. Understanding the pH-dependent alteration in EPS constituents, and associated functional groups of a marine bacterium will provide better insight into the adaptability of the bacteria in future ocean acidification scenarios. The strain was found to tolerate and form biofilm up to pH 4, with the maximum biofilm formation at pH 6. EPS yield and the synthesis of the key components of the EPS, including carbohydrate, protein, and lipid, were found maximum at pH 6. Changes in biofilm formation patterns and various topological parameters at varying pH/pCO2 conditions were observed. A cellular chaining pattern was observed at pH 4, and maximum biofilm formation was obtained at pH 6 with biomass of 5.28582 ± 0.5372 μm3/μm2 and thickness of 9.982 ± 1.5288 μm. Structural characterization of EPS showed changes in various functional groups of constituent macromolecules with varying pH. The amorphous nature of the EPS and the changes in linkages and associated functional groups (-R2CHOR, –CH3, and –CH2) with pH variation was confirmed. EPS showed a two-step degradation with a maximum weight loss of 59.147% and thermal stability up to 480 °C at pH 6. The present work efficiently demonstrates the role of EPS in providing structural and functional stability to the biofilm in varying pH conditions. The findings will provide a better understanding of the adaptability of marine bacteria in the future effect of ocean acidification.

Continue reading ‘Variable pH and subsequent change in pCO2 modulates the biofilm formation, synthesis of extracellular polymeric substances, and survivability of a marine bacterium Bacillus stercoris GST-03′

Interactive effects of CO2, temperature, irradiance, and nutrient limitation on the growth and physiology of the marine cyanobacterium Synechococcus (Cyanophyceae)

Published 14 September 2022 Science Closed
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The marine cyanobacterium Synechococcus elongatus was grown in a continuous culture system to study the interactive effects of temperature, irradiance, nutrient limitation, and the partial pressure of CO2 (pCO2) on its growth and physiological characteristics. Cells were grown on a 14:10 h light:dark cycle at all combinations of low and high irradiance (50 and 300 μmol photons ⋅ m−2 ⋅ s−1, respectively), low and high pCO2 (400 and 1000 ppmv, respectively), nutrient limitation (nitrate-limited and nutrient-replete conditions), and temperatures of 20–45°C in 5°C increments. The maximum growth rate was ~4.5 · d−1 at 30–35°C. Under nutrient-replete conditions, growth rates at most temperatures and irradiances were about 8% slower at a pCO2 of 1000 ppmv versus 400 ppmv. The single exception was 45°C and high irradiance. Under those conditions, growth rates were ~45% higher at 1000 ppmv. Cellular carbon:nitrogen ratios were independent of temperature at a fixed relative growth rate but higher at high irradiance than at low irradiance. Initial slopes of photosynthesis–irradiance curves were higher at all temperatures under nutrient-replete versus nitrate-limited conditions; they were similar at all temperatures under high and low irradiance, except at 20°C, when they were suppressed at high irradiance. A model of phytoplankton growth in which cellular carbon was allocated to structure, storage, or the light or dark reactions of photosynthesis accounted for the general patterns of cell composition and growth rate. Allocation of carbon to the light reactions of photosynthesis was consistently higher at low versus high light and under nutrient-replete versus nitrate-limited conditions.

Continue reading ‘Interactive effects of CO2, temperature, irradiance, and nutrient limitation on the growth and physiology of the marine cyanobacterium Synechococcus (Cyanophyceae)’

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