Effects of ocean acidification on resident and active microbial communities of Stylophora pistillata

Ocean warming and ocean acidification (OA) are direct consequences of climate change and affect coral reefs worldwide. While the effect of ocean warming manifests itself in increased frequency and severity of coral bleaching, the effects of ocean acidification on corals are less clear. In particular, long-term effects of OA on the bacterial communities associated with corals are largely unknown. In this study, we investigated the effects of ocean acidification on the resident and active microbiome of long-term aquaria-maintained Stylophora pistillata colonies by assessing 16S rRNA gene diversity on the DNA (resident community) and RNA level (active community). Coral colony fragments of S. pistillata were kept in aquaria for 2 years at four different pCO2 levels ranging from current pH conditions to increased acidification scenarios (i.e., pH 7.2, 7.4, 7.8, and 8). We identified 154 bacterial families encompassing 2,047 taxa (OTUs) in the resident and 89 bacterial families including 1,659 OTUs in the active communities. Resident communities were dominated by members of Alteromonadaceae, Flavobacteriaceae, and Colwelliaceae, while active communities were dominated by families Cyclobacteriacea and Amoebophilaceae. Besides the overall differences between resident and active community composition, significant differences were seen between the control (pH 8) and the two lower pH treatments (7.2 and 7.4) in the active community, but only between pH 8 and 7.2 in the resident community. Our analyses revealed profound differences between the resident and active microbial communities, and we found that OA exerted stronger effects on the active community. Further, our results suggest that rDNA- and rRNA-based sequencing should be considered complementary tools to investigate the effects of environmental change on microbial assemblage structure and activity.

Continue reading ‘Effects of ocean acidification on resident and active microbial communities of Stylophora pistillata’

A marine-biology-centric definition of ocean connectivity and the law of the sea

The inter-connectedness of marine ecosystems has been repeatedly acknowledged in the relevant literature as well as in policy briefs. Against this backdrop, this article aims at further reflecting on the question of to what extent the law of the sea takes account of or disregards ocean connectivity. In order to address this question, this article starts by providing a brief overview of the notion of ocean connectivity from a marine science perspective, before taking a closer look at the extent to which the law of the sea incorporates the scientific imperative of ocean connectivity in the context of four examples: (i) straits, (ii) climate change and ocean acidification, (iii) salmon and (iv) the ecosystem approach to fisheries. Tying the findings of the different examples together, this study concludes by stressing the need of accommodating ocean connectivity not only in the interpretation and implementation of the existing law (of the sea) but also in its further development.

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Life support systems operator, Summerland Key, FL

Location: Elizabeth Moore International Center for Coral Reef Research and Restoration (IC2R3), Summerland Key, Florida

Primary Function: Responsible for the construction, operation, and maintenance of both open and closed seawater systems and their associated equipment. Assist in operation and maintenance of the Climate Ocean Acidification System.

Primary Duties:

  • Follow preventative maintenance program for all equipment
  • Piping system installation and repair
  • Operate all seawater systems including heater/chiller, pumps, ozone & nitrogen generation
  • Assist CAOS technician with its operation and maintenance
  • Respond to system alarms and perform corrective actions as needed 
  • Additional duties as needed to support other Mote research/restoration projects, assist visiting scientists, maintenance and repair of building and facility, and other tasks related to the daily operation of a full service marine laboratory.

Minimum Qualifications or Requirements:

  • Ability to work outside in all weather conditions as well as in tight quarters is required
  • Valid Florida driver’s license.

Required Knowledge, Skills, and Abilities:

  • Ability to troubleshoot life support systems
  • Capable of performing repair and maintenance to mechanical systems
  • Ability to work with PVC up to 4”
  • Ability to safely use hand and power tools
  • Ability to adapt to a changing environment, work independently on certain tasks with minimal direct supervision, and good practical problem-solving abilities.
  • Normal hours are 8:00 – 5:00 Tuesday – Saturday; however, occasional weekend and evening hours may be required.

To Apply:

Interested applicants should apply on line by choosing 2021 Life Support Systems Operator, Summerland Key, FL IC2R3 at  https://mote.smapply.org/prog/job_applicants or mail a single package including cover letter, resume or c.v. and the contact information for three references to Mote Marine Laboratory, Attn: Human Resources, 1600 Ken Thompson Parkway, Sarasota, FL 34236 before 5pm January 7, 2022.

All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, disability, protected veteran status or other protected category.  Mote participates in E-Verify.

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Surface pCO2 variability in two contrasting basins of North Indian Ocean using satellite data

Highlights

  • The spatiotemporal variability of surface pCO2 in the BoB is dominated by the influx of riverine freshwater.
  • SST and chlorophyll are the decisive factors governing the variability of pCO2 in the AS.
  • Tropical cyclone induced surface cooling and biogeochemical processes, affecting the pCO2 distribution in the BoB.

Abstract

The spatial and temporal variability of the partial pressure of carbon dioxide (pCO2) over the northern tropical Indian Ocean was estimated based on satellite-derived sea surface temperature (SST), sea surface salinity (SSS), and chlorophyll concentration (Chl-a). The distribution of sea surface pCO2 is controlled by various physical processes, such as mixing, entrainment, upwelling, and advection, and by associated biological processes, such as phytoplankton blooms. The results showed lower surface water pCO2 over the Bay of Bengal (BoB) (< 300 μatm) as compared to the Arabian Sea (AS), which could be attributed to low salinity during the northeast monsoon season (December–January) in the BoB. High pCO2 values (> 500 μatm) were found near the Somali coast during the southwest monsoon season (June–August) caused by intense coastal upwelling. The pCO2 over BoB (400–450 μatm) was more than that of the AS in the fall inter-monsoon season (September–November) as a response to the relatively warmer SST over the BoB. The highest spatiotemporal variability of surface pCO2 was observed in the western AS near to the coast and over the northern BoB as a response to the higher variability in biological productivity and salinity, respectively, over these regions. The effect of tropical cyclones on pCO2 variability over the BoB was also assessed in this study. The sea surface pCO2 values were found to be much smaller along the cyclone track after the passage of cyclones because of the strong SST drop and the sudden phytoplankton blooms caused by the entrainment and vertical mixing of subsurface cold and nutrient-rich water with surface water. The cyclone-induced surface cooling and the associated decrease in surface water pCO2 were found to be higher after the passage of the Madi cyclone compared to the Hudhud cyclone.

Continue reading ‘Surface pCO2 variability in two contrasting basins of North Indian Ocean using satellite data’

Molecular mechanisms of sperm motility are conserved in an early-branching metazoan

Significance

Reef-building corals are the keystone species of the world’s most biodiverse yet threatened marine ecosystems. Coral reproduction, critical for reef resilience, requires that coral sperm swim through the water column to reach the egg. However, little is known about the mechanisms that regulate coral sperm motility. We found here that coral sperm motility is pH dependent and that activation of motility requires signaling via the pH-sensing enzyme soluble adenylyl cyclase. This study reveals the deep conservation of a sperm activation pathway from humans to corals, presenting the first comprehensive examination of the molecular mechanisms regulating sperm motility in an early-diverging animal. These results are critical for understanding the resilience of this sensitive life stage to a changing marine environment.

Abstract

Efficient and targeted sperm motility is essential for animal reproductive success. Sperm from mammals and echinoderms utilize a highly conserved signaling mechanism in which sperm motility is stimulated by pH-dependent activation of the cAMP-producing enzyme soluble adenylyl cyclase (sAC). However, the presence of this pathway in early-branching metazoans has remained unexplored. Here, we found that elevating cytoplasmic pH induced a rapid burst of cAMP signaling and triggered the onset of motility in sperm from the reef-building coral Montipora capitata in a sAC-dependent manner. Expression of sAC in the mitochondrial-rich midpiece and flagellum of coral sperm support a dual role for this molecular pH sensor in regulating mitochondrial respiration and flagellar beating and thus motility. In addition, we found that additional members of the homologous signaling pathway described in echinoderms, both upstream and downstream of sAC, are expressed in coral sperm. These include the Na+/H+ exchanger SLC9C1, protein kinase A, and the CatSper Ca2+ channel conserved even in mammalian sperm. Indeed, the onset of motility corresponded with increased protein kinase A activity. Our discovery of this pathway in an early-branching metazoan species highlights the ancient origin of the pH-sAC-cAMP signaling node in sperm physiology and suggests that it may be present in many other marine invertebrate taxa for which sperm motility mechanisms remain unexplored. These results emphasize the need to better understand the role of pH-dependent signaling in the reproductive success of marine animals, particularly as climate change stressors continue to alter the physiology of corals and other marine invertebrates.

Continue reading ‘Molecular mechanisms of sperm motility are conserved in an early-branching metazoan’

IOCCP/ G7 FSOI meeting launches development of a Surface Ocean CO2 Monitoring Strategy

On 25 November 2021, the EU coordinator of the G7 Future of the Seas and Oceans Initiative (FSOI) Coordination Centre hosted a one-day workshop jointly with the 16th Session of the Scientific Steering Committee of the International Ocean Carbon Coordination Project (IOCCP) at the IOCCP office in Sopot, Poland. The event served to launch the activity “A Global Surface Ocean CO2 Monitoring Strategy“.

This activity, endorsed by the G7 FSOI at its working group meeting in June 2021, will run for two years to develop an internationally-agreed strategy and implementation plan for a global network that can be used by governments for coordinated investment actions. The activity will establish a scientific steering group and an International Mission Team. It will build on the existing Surface Ocean CO2Reference Observing Network (SOCONET), and include plans for a full-time coordinator as part of the OceanOPS Centre and support to operationalise the data management centres and the data synthesis project – Surface Ocean CO₂ Atlas (SOCAT).

This activity gained momentum at COP26 following the announcement by NOAA Administrator Dr. Richard Spinrad to establish a globally operational Surface Ocean CO2 Reference Network: The network will integrate established and proposed national and regional surface ocean carbon dioxide (CO2) research and monitoring efforts into a global framework, enabling countries to track changes in global ocean uptake of CO2 over time. Through international engagement, NOAA will facilitate the development of the global network and produce high-value products, such as observation-based annual updates of ocean carbon uptake and changes in ocean acidification, that are critical for decision making about ocean-based mitigation options and marine ecosystem health.”

The meeting was led by Maria Hood, EU coordinator* of the G7 FSOI Coordination Centre, IOCCP Director Maciej Telszewski, and IOCCP lead expert Richard Sanders, Director of the EU Integrated Carbon Observing System Ocean Thematic Centre (ICOS-OTC). The IOCCP working group will develop a strategic outline and host an international workshop in the first quarter of 2022 with a goal of a first public release of the strategy in time for the 2022 UN Ocean Conference in Lisbon next June.

*The EU coordination of the G7 FSOI Coordination Centre is hosted by Mercator Ocean International as part of the EU4OceanObs Action with funding from the European Union. For more information, click here.

EU4OceanObs, 2 December 2021. Article.

Continue reading ‘IOCCP/ G7 FSOI meeting launches development of a Surface Ocean CO2 Monitoring Strategy’

Protecting our oceans, our future: what can EU do? (text & video)

Speakers:

Dr Susan Gardner, Director, Ecosystems Division, UN Environment Programme; Humberto Delgado Rosa, Director, Natural Capital, DG Environment, European Commission; Karlijn Steinbusch, Program Manager People & Nature, Adessium

Moderator:

Stefan Sipka, Policy Analyst, European Policy Centre

There is growing recognition of the need to address the climate and ecological crises, but the role of oceans is often forgotten. Unsustainable aqua-culture, overfishing, climate change, ocean acidification, plastic waste, marine engineering and oil drilling, are having a devastating impact on marine life, and, consequently, threaten human well-being. Over-fishing, in particular, is weakening the ability of oceans to act as a natural carbon sink, thus undermining climate action.

The year 2021 has seen new efforts to raise the ambition for protecting oceans and marine ecosystems. The EU Biodiversity Strategy for 2030 sets out a protection target of at least 30% of the sea in the EU waters. Likewise, the 30% target for protecting oceans worldwide by 2030 is being discussed in the framework of the UN Convention on Biological Diversity. The 26th UN Climate Change Conference of the Parties (COP26) in Glasgow also brought increased awareness about the potential role of oceans in contributing to climate mitigation.

This Policy Dialogue explored the role of oceans in the climate and ecological crises, as well as the state of play and prospects for protecting oceans and marine ecosystems in the EU and beyond, including the role of the EU.

Continue reading ‘Protecting our oceans, our future: what can EU do? (text & video)’

Coastal observatory for climate, CO2 and acidification for the global South society (COCAS)

Sorbonne Université, LOCEAN-IPSL

Change humanity’s relationship with the ocean, Create a digital representation of the Ocean, Develop a sustainable and equitable ocean economy, Expand the Global Ocean Observing System, Indian Ocean, North Atlantic Ocean, North Pacific Ocean, Project, Protect and restore ecosystems and biodiversity, Skills, knowledge and technology for all, South Atlantic Ocean, South Pacific Ocean, Sustainably feed the global population, Unlock ocean-based solutions to climate change

The COCAS community builds on and uses a science-based decision support system, for sustainable development of the marine Exclusive Economic Zones of the Global South countries.

Its mission is three-fold:

  • First, to implement and sustain coastal ocean long-term observatories assessing ongoing marine environmental changes and their impact on a rich marine biodiversity and multicultural populations;
  • Second, to create a common language and common practices for stakeholders based on data, intelligent information, and technology;
  • Third, to give birth to a new generation of scientists, end-users and decision-makers, working together for the integrated coastal management of tomorrow in the Global South.

Start Date: 01/04/2021

End Date: 31/12/2030

This project is hosted by the programme Ocean Observing Co-Design: evolving ocean observing for a sustainable future.

Contacts

Diana Ruiz-Pino: diana.ruiz-pino@locean.ipsl.fr
Alban Lazar: alban.lazar@locean.ipsl.fr

Continue reading ‘Coastal observatory for climate, CO2 and acidification for the global South society (COCAS)’

Aircraft reveal a surprisingly strong Southern Ocean carbon sink

The Southern Ocean is indeed a significant carbon sink — absorbing a large amount of the excess carbon dioxide emitted into the atmosphere by human activities — according to a new study led by the National Center for Atmospheric Research (NCAR).

The findings provide clarity about the role the icy waters surrounding Antarctica play in buffering the impact of increasing greenhouse gas emissions, after research published in recent years suggested the Southern Ocean might be less of a sink than previously thought.

The new study, published this week in the journal Science, makes use of observations from research aircraft flown during three field projects over nearly a decade, as well as a collection of atmospheric models, to determine that the Southern Ocean takes up significantly more carbon than it releases. The research also highlights the power that airborne observations have to reveal critical patterns in the global carbon cycle.

“You can’t fool the atmosphere,” said NCAR scientist Matthew Long, the paper’s lead author. “While measurements taken from the ocean surface and from land are important, they are too sparse to provide a reliable picture of air-sea carbon flux. The atmosphere, however, can integrate fluxes over large expanses. Airborne measurements show a drawdown of CO2 in the lower atmosphere over the Southern Ocean surface in summer, indicating carbon uptake by the ocean.”

The research is funded by the National Science Foundation (NSF), which is NCAR’s sponsor, as well as by NASA and NOAA.

Continue reading ‘Aircraft reveal a surprisingly strong Southern Ocean carbon sink’

Strong Southern Ocean carbon uptake evident in airborne observations

Up in the air

Understanding ocean-atmospheric carbon dioxide (CO2) fluxes in the Southern Ocean is necessary for quantifying the global CO2 budget, but measurements in the harsh conditions there make collecting good data difficult, so a quantitative picture still is out of reach. Long et al. present measurements of atmospheric CO2 concentrations made by aircraft and show that the annual net flux of carbon into the ocean south of 45°S is large, with stronger summertime uptake and less wintertime outgassing than other recent observations have indicated. —HJS

Abstract

The Southern Ocean plays an important role in determining atmospheric carbon dioxide (CO2), yet estimates of air-sea CO2 flux for the region diverge widely. In this study, we constrained Southern Ocean air-sea CO2 exchange by relating fluxes to horizontal and vertical CO2 gradients in atmospheric transport models and applying atmospheric observations of these gradients to estimate fluxes. Aircraft-based measurements of the vertical atmospheric CO2 gradient provide robust flux constraints. We found an annual mean flux of –0.53 ± 0.23 petagrams of carbon per year (net uptake) south of 45°S during the period 2009–2018. This is consistent with the mean of atmospheric inversion estimates and surface-ocean partial pressure of CO2 (PCO2)–based products, but our data indicate stronger annual mean uptake than suggested by recent interpretations of profiling float observations.

Continue reading ‘Strong Southern Ocean carbon uptake evident in airborne observations’

Seasonal variation of sea surface pH and its controls in the Jiaozhou Bay, China

Highlights

  • Seasonal variation in pH covering an annual cycle in the Jiaozhou Bay is shown.
  • Temperature seems to be a dominant factor of pH seasonal variation.
  • Biological effect is the most important indeed, but offset by air-sea exchange.
  • Deciphering pH controlling processes in a quantitative manner is preferred.

Abstract

Coastal waters usually have intense and complicated biogeochemical processes, the interaction of which makes a challenge to identify the dominant factor of pH natural variations such as seasonal signals. In this study, we report seasonal variation and controls of sea surface pH in the highly urbanized Jiaozhou Bay (JZB) based on four cruises conducted in March, July, October 2014 and January 2015. With sea surface temperature increasing, surface pH on the NBS (NIST) scale decreased from 8.16 ± 0.03 in early spring and 8.19 ± 0.02 in winter to 7.96 ± 0.05 in summer and 7.98 ± 0.01 in autumn. The correlation analyses between pH and temperature shows that temperature seems to be a dominant factor of pH seasonal variation. But the mass balance model indicates that biological effect is the most important for the seasonal variation of pH in the JZB. These two apparently different conclusions are due to the fact that the biological effect on pH is greatly weakened (offset by 73%) by the effect of air-sea CO2 exchange. This study highlights the importance of deciphering pH controlling processes in a quantitative manner particularly in shallow and human activities strongly influenced coastal waters, where these processes usually interact each other and readily obscure the dominant factor.

Continue reading ‘Seasonal variation of sea surface pH and its controls in the Jiaozhou Bay, China’

Effect of increased CO2 on iron-light-CO2 co-limitation of growth in a marine diatom

Light affects iron (Fe) growth requirements in marine phytoplankton while CO2 can influence energy allocation and light sensitivity. Therefore, ongoing increases in seawater CO2 concentrations could impact the growth of Fe- and light-limited phytoplankton. In this study, Phaeodactylum tricornutum was used as a model diatom to examine the interactive effects of Fe, light, and CO2 on photosynthesis, growth, and protein expression in marine phytoplankton. Low concentration of biologically available inorganic iron (Fe′) and low-light intensity decreased specific rates of carbon (C)-fixation and growth, and the two together had an even greater effect, indicating a co-limitation. Increased partial pressure of CO2 from its current value (400 μatm) to 750 μatm had no effect at growth sufficient levels of Fe and light, but increased C-fixation and growth rate under Fe or light limitation, and had an even greater effect in Fe and light co-limited cells. The results suggest that ongoing increases in CO2 may increase C-fixation rates in Fe- and light-limited and co-limited regions, which cover at least 30% of the ocean. Measurements of photosynthetic proteins in photosystems II and I, and transcripts of proteins involved in CO2 concentrating mechanisms (CCMs), photorespiration, and antioxidant protection, suggest that the benefit of increased CO2 in the Fe- and light-limited cells was from a downregulation of CCMs and resultant decreased demands for energy supplied from photosynthesis, and from decreased rates of photorespiration, which consumes photosynthetically produced ATP and NADPH. A decrease in oxidative stress with increased CO2 also contributed.

Continue reading ‘Effect of increased CO2 on iron-light-CO2 co-limitation of growth in a marine diatom’

How do we stop the decline of the ocean?

Date: 8 December 2021

Time: 11:00 CET

The ocean, which covers 70 percent of our planet and supplies half of the oxygen we breathe, is in decline. The burning of fossil fuels and global warming are changing its weather-regulating systemsraising its waters to threatening heights and acidifying its pH balance beyond what its food- and air-giving species can survive.

And yet, in recent years marked by climate action, land has been the primary focus, leaving the ocean lacking the science, policy and funding it needs in order to continue sustaining its life – and ours.

In this GLF Live on 8 December at 11:00 CET, Dorothée Herr, a preliminary expert on ocean policy, will discuss ongoing efforts to rebalance the ‘green’ and the ‘blue’ in the context of climate change and what research, funding, decisions and developments are needed most to curb the degradation of our waters.

Dorothée Herr is the manager for Ocean and Climate Change at the Global Marine and Polar Programme (GMPP) at the International Union for Conservation of Nature (IUCN). She joined IUCN in 2009 and is now leading the IUCN’s international policy and private finance engagement on coastal and marine nature-based solutions. Ms. Herr has authored and co-authored a suite of articles and reports on ocean acidification, blue carbon as well as on coastal and marine nature-based solutions in the context of the UNFCCC, CBD and other international policy fora. Ms. Herr has developed, with a team of financial experts, the Blue Natural Capital Financing Facility (BNCFF) as well as the Subnational Climate Fund (SCF), and is managing their implementation since 2018 and 2021 respectively.

Ms. Herr received her masters degree in Environmental Change and Management from Oxford University in the U.K. and her diploma in Geography from the University of Heidelberg in Germany.

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Changing smells? How pH can impact signalling molecules in marine systems

Date: 7 December 2021

Time: 13:30

Location: online via Zoom platform

REGISTER HERE

Ocean acidification is well-known to affect the calcification, physiology, and behaviour of marine organisms. Recently, it was discovered that the associated changes in ocean pH can also directly impact the signalling molecules that mediate essential interactions of marine animals. Many ecosystem services rely on processes and interactions of organisms that are mediated through chemicals. This seminar gives an overview of the effects of pH on signalling molecules and biotoxins known to date, the interdisciplinary methods employed to uncover them and how combining supercomputing and behaviour observation can help predict potential impacts.

About our speaker:
Christina C. Roggatz has done an Erasmus Mundus MSc Marine Biodiversity and Conservation (2012) with a thesis at CCMAR, a PhD in Chemistry (2017) University of Hull, and is currently a Research Fellow.

Continue reading ‘Changing smells? How pH can impact signalling molecules in marine systems’

Ocean acidification research opportunity: advancing pH measurement technologies in the Delaware Estuary and Delaware’s Inland Bays

The Delaware Environmental Institute is accepting applications for an undergraduate research opportunity for a project called, “Advancing pH measurement technologies for coastal ocean acidification monitoring in the Delaware Estuary and Delaware’s Inland Bays,” with Prof. Wei-Jun Cai’s research group.

A significant portion of atmospheric CO2 is absorbed by our oceans. While this removes large portions of CO2 from our air, potentially reducing global warming, it gradually acidifies our oceans. Furthermore, these changes in acidification occur at a greater rate in nearshore waters as compared to the open ocean.

This gradual increase in ocean pH interferes with the ability of many ocean organisms to develop shells and skeletons, having disastrous effects on oyster reefs, coral reefs and ultimately the human food chain. Delaware’s shellfish aquaculture industry is still in its infancy so understanding the impacts of acidification on local ecosystems is crucial for this industry to thrive. Despite the urgent threats that acidification poses to Delaware’s estuarine and coastal ocean waters and the resources therein, we currently lack the appropriate tools to properly measure and assess its impacts in state waters. Without acidification monitoring, the development of effective adaptation and mitigation strategies in these areas is impeded.

The undergraduate student selected for this opportunity will learn practices and methods associated with mCP-based spectrophotometric pH analysis and with sensor operation and deployment.

To apply send a cover letter, resume and transcript to Yolanda Williams-Bey at yolanda@udel.edu no later than Friday, Dec. 10, 2021.

Continue reading ‘Ocean acidification research opportunity: advancing pH measurement technologies in the Delaware Estuary and Delaware’s Inland Bays’

OA-ICC bibliographic database updated

An updated version of the OA-ICC bibliographic database is available online.

The database currently contains 9,161 references and includes citations, abstracts and assigned keywords. Updates are made every month.

The database is available as a group on Zotero. Subscribe online or, for a better user experience, download the Zotero desktop application and sync with the group OA-ICC in Zotero. Please see the “User instructions” for further details.

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CO2-driven seawater acidification increases cadmium toxicity in a marine copepod

Highlights

  • Copepods were interactively exposed to higher pCO2 (1000 μatm) and Cd (500 μg/L).
  • Elevated pCO2 significantly increased Cd bioaccumulation in Tigriopus japonicus.
  • Copepods enhanced energy production and stress response to counteract Cd toxicity.
  • Increased pCO2 aggravated Cd-induced oxidative damage and apoptosis.
  • Seawater acidification will potentially boost Cd toxicity in marine copepods.

Abstract

Here, we examined the 48-h acute toxicity of cadmium (Cd) in the marine copepod Tigriopus japonicus under two pCO2 concentrations (400 and 1000 μatm). Subsequently, T. japonicus was interactively exposed to different pCO2 (400, 1000 μatm) and Cd (control, 500 μg/L) treatments for 48 h. After exposure, biochemical and physiological responses were analyzed for the copepods. The results showed that the 48-h LC50 values of Cd were calculated as 12.03 mg/L and 9.08 mg/L in T. japonicus, respectively, under 400 and 1000 μatm pCO2 conditions. Cd exposure significantly promoted Cd exclusion/glycolysis, detoxification/stress response, and oxidative stress/apoptosis while it depressed that of antioxidant capacity. Intriguingly, CO2-driven acidification enhanced Cd bioaccumulation and its toxicity in T. japonicus. Overall, our study provides a mechanistic understanding about the interaction between seawater acidification and Cd pollution in marine copepods.

Continue reading ‘CO2-driven seawater acidification increases cadmium toxicity in a marine copepod’

Air-sea CO2 exchange in the Strait of Gibraltar

The seasonal and spatial variability of the CO2 system and air-sea fluxes were studied in surface waters of the Strait of Gibraltar between February 2019 and March 2021. High-resolution data was collected by a surface ocean observation platform aboard a volunteer observing ship. The CO2 system was strongly influenced by temperature and salinity fluctuations forced by the seasonal and spatial variability in the depth of the Atlantic–Mediterranean Interface layer and by the tidal and wind-induced upwelling. The changes in seawater CO2 fugacity (fCO2,sw) and fluxes were mainly driven by temperature despite the significant influence of non-thermal processes in the southernmost part. The thermal to non-thermal effect ratio (T/B) reached maximum values in the northern section (>1.8) and minimum values in the southern section (<1.30). The fCO2,sw increased with temperature by 9.02 ± 1.99 μatm °C–1 (r2 = 0.86 and ρ = 0.93) and 4.51 ± 1.66 μatm °C–1 (r2 = 0.48 and ρ = 0.69) in the northern and southern sections, respectively. The annual cycle of total inorganic carbon normalized to a constant salinity of 36.7 (NCT) was assessed. Net community production processes described 93.5–95.6% of the total NCT change, while air-sea exchange and horizontal and vertical advection accounted for <4.6%. The fCO2,sw in the Strait of Gibraltar since 1999 has been fitted to an equation with an interannual trend of 2.35 ± 0.06 μatm year–1 and a standard error of estimate of ±12.8 μatm. The seasonality of the air-sea CO2 fluxes reported the behavior as a strong CO2 sink during the cold months and as a weak CO2 source during the warm months. Both the northern and the southern sections acted as a net CO2 sink of −0.82 and −1.01 mol C m–2 year–1, respectively. The calculated average CO2 flux for the entire area was −7.12 Gg CO2 year–1 (−1.94 Gg C year–1).

Continue reading ‘Air-sea CO2 exchange in the Strait of Gibraltar’

Gene expression and epigenetic responses of the marine Cladoceran, Evadne nordmanni, and the copepod, Acartia clausi, to elevated CO2

Characterizing the capacity of marine organisms to adapt to climate change related drivers (e.g., pCO2 and temperature), and the possible rate of this adaptation, is required to assess their resilience (or lack thereof) to these drivers. Several studies have hypothesized that epigenetic markers such as DNA methylation, histone modifications and noncoding RNAs, act as drivers of adaptation in marine organisms, especially corals. However, this hypothesis has not been tested in zooplankton, a keystone organism in marine food webs. The objective of this study is to test the hypothesis that acute ocean acidification (OA) exposure alters DNA methylation in two zooplanktonic species—copepods (Acartia clausii) and cladocerans (Evadne nordmanii). We exposed these two species to near-future OA conditions (400 and 900 ppm pCO2) for 24 h and assessed transcriptional and DNA methylation patterns using RNA sequencing and Reduced Representation Bisulfite Sequencing (RRBS). OA exposure caused differential expression of genes associated with energy metabolism, cytoskeletal and extracellular matrix functions, hypoxia and one-carbon metabolism. Similarly, OA exposure also caused altered DNA methylation patterns in both species but the effect of these changes on gene expression and physiological effects remains to be determined. The results from this study form the basis for studies investigating the potential role of epigenetic mechanisms in OA induced phenotypic plasticity and/or adaptive responses in zooplanktonic organisms.

Continue reading ‘Gene expression and epigenetic responses of the marine Cladoceran, Evadne nordmanni, and the copepod, Acartia clausi, to elevated CO2’

Rise of the turfs: the simplification of marine ecosystems under ocean acidification

Date: 9 December 2021

Time: 13:30-15:00

Location: Lab4 L4F01 Seminar Room

Zoom link

Description:

Human activities are rapidly changing the structure of coastal marine ecosystems, but the ecological consequences of these changes remain uncertain. Natural analogues of futuristic conditions are increasingly being used to assess the likely effects of rising atmospheric CO2 emissions on marine ecosystems. Here, using a CO2 seep in Japan, we show how ocean acidification causes habitat and biodiversity loss, resulting in the simplification of marine ecosystems. This simplification involves structurally complex habitat-forming species (including corals and larger macrophytes) being replaced by more homogenous and simple turf algal habitats. Such ecological shifts are concerning because they result in habitats that have less ecological and human value. Moreover, once these ecological shifts occur, ocean acidification-driven stabilising feedback loops ‘lock-in’ these novel turf systems making them particularly difficult to reverse. By understanding the ecological processes responsible for driving community shifts, we can better assess how future communities and ecosystems are likely to be altered by ocean acidification. Taken together, we demonstrate how the simplification of marine habitats by increased CO2 levels will cascade through the ecosystem and will have severe consequences for the provision of goods and services.

Biography:

Ben Harvey is a tenure-track Assistant Professor at the Shimoda Marine Research Center, University of Tsukuba in Japan. After receiving his doctoral degree in marine climate change ecology from Aberystwyth University in the UK, he worked for 1-year as a post-doctoral researcher and lecturer of marine community ecology and genetics. In 2016, he took his position as an Assistant Professor at the Shimoda Marine Research Center in Japan where he seeks to understand how ongoing and future environmental changes will impact our oceans. Specifically, his research group focus on using multidisciplinary approaches combining field surveys, manipulative experiments, molecular and physiological techniques, and modelling, to understand how changes in environmental conditions (focussing on ocean acidification, warming, and marine heatwaves) will alter the biodiversity, community structure and functioning of future marine ecosystems.

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