Archive Page 154

Is climate disrupting maritime boundaries?

Published 26 September 2022 Web sites and blogs Closed
The rules for atolls and reefs in international law are already murky and subject to interpretation. Image by PR HANDOUT IMAGE PHOTO

Climate change is disrupting the shape and presence of coral islands across the Indo-Pacific, creating uncertainties for legal maritime zones and small states, say legal experts.

Atolls and reefs naturally grow and shrink due to complex processes yet to be fully understood.

However global warming is disrupting them further and leading to fresh uncertainties, according to research conducted at the University of Sydney.

Lead author Dr Thomas Fellowes says new technologies and approaches coupled with expanded analysis of coral behaviour may be needed to help dispel some of the precariousness and solidify claims.

“Coral reef islands are the legal basis for many large maritime zones,” he said.

“Hence, continued climate disruptions may have substantial impact not only for small island states but in hotly contested boundary disputes in places like the South China Sea.

“It’s a perfect storm that is bringing instability and uncertainty to what are already difficult boundaries to determine with any great accuracy.”

The rules for atolls and reefs in international law – already murky and subject to interpretation due to their shifting nature – will be under greater stress as sea levels rise and acidification disrupts reef integrity.

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Cold-water coral ecosystems under future ocean change: live coral performance vs. framework dissolution and bioerosion

Published 23 September 2022 Science Closed
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Physiological sensitivity of cold-water corals to ocean change is far less understood than of tropical corals and very little is known about the impacts of ocean acidification and warming on degradative processes of dead coral framework. In a 13-month laboratory experiment, we examined the interactive effects of gradually increasing temperature and pCO2 levels on survival, growth, and respiration of two prominent color morphotypes (colormorphs) of the framework-forming cold-water coral Lophelia pertusa, as well as bioerosion and dissolution of dead framework. Calcification rates tended to increase with warming, showing temperature optima at ~ 14°C (white colormorph) and 10–12°C (orange colormorph) and decreased with increasing pCO2. Net dissolution occurred at aragonite undersaturation (ΩAr < 1) at ~ 1000 μatm pCO2. Under combined warming and acidification, the negative effects of acidification on growth were initially mitigated, but at ~ 1600 μatm dissolution prevailed. Respiration rates increased with warming, more strongly in orange corals, while acidification slightly suppressed respiration. Calcification and respiration rates as well as polyp mortality were consistently higher in orange corals. Mortality increased considerably at 14–15°C in both colormorphs. Bioerosion/dissolution of dead framework was not affected by warming alone but was significantly enhanced by acidification. While live corals may cope with intermediate levels of elevated pCO2 and temperature, long-term impacts beyond levels projected for the end of this century will likely lead to skeletal dissolution and increased mortality. Our findings further suggest that acidification causes accelerated degradation of dead framework even at aragonite saturated conditions, which will eventually compromise the structural integrity of cold-water coral reefs.

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Light history modulates growth and photosynthetic responses of a diatom to ocean acidification and UV radiation

Published 23 September 2022 Science Closed
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To examine the synergetic effects of ocean acidification (OA) and light intensity on the photosynthetic performance of marine diatoms, the marine centric diatom Thalassiosira weissflogii was cultured under ambient low CO2 (LC, 390 μatm) and elevated high CO2 (HC, 1000 μatm) levels under low-light (LL, 60 μmol m−2 s−1) or high-light (HL, 220 μmol m−2 s−1) conditions for over 20 generations. HL stimulated the growth rate by 128 and 99% but decreased cell size by 9 and 7% under LC and HC conditions, respectively. However, HC did not change the growth rate under LL but decreased it by 9% under HL. LL combined with HC decreased both maximum quantum yield (FV/FM) and effective quantum yield (ΦPSII), measured under either low or high actinic light. When exposed to UV radiation (UVR), LL-grown cells were more prone to UVA exposure, with higher UVA and UVR inducing inhibition of ΦPSII compared with HL-grown cells. Light use efficiency (α) and maximum relative electron transport rate (rETRmax) were inhibited more in the HC-grown cells when UVR (UVA and UVB) was present, particularly under LL. Our results indicate that the growth light history influences the cell growth and photosynthetic responses to OA and UVR.

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Environmental memory gained from exposure to extreme pCO2 variability promotes coral cellular acid–base homeostasis

Published 23 September 2022 Science Closed
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Ocean acidification is a growing threat to coral growth and the accretion of coral reef ecosystems. Corals inhabiting environments that already endure extreme diel pCO2 fluctuations, however, may represent acidification-resilient populations capable of persisting on future reefs. Here, we examined the impact of pCO2 variability on the reef-building coral Pocillopora damicornis originating from reefs with contrasting environmental histories (variable reef flat versus stable reef slope) following reciprocal exposure to stable (218 ± 9) or variable (911 ± 31) diel pCO2 amplitude (μtam) in aquaria over eight weeks. Endosymbiont density, photosynthesis and net calcification rates differed between origins but not treatment, whereas primary calcification (extension) was affected by both origin and acclimatization to novel pCO2 conditions. At the cellular level, corals from the variable reef flat exhibited less intracellular pH (pHi) acidosis and faster pHi recovery rates in response to experimental acidification stress (pH 7.40) than corals originating from the stable reef slope, suggesting environmental memory gained from lifelong exposure to pCO2 variability led to an improved ability to regulate acid–base homeostasis. These results highlight the role of cellular processes in maintaining acidification resilience and suggest that prior exposure to pCO2 variability may promote more acidification-resilient coral populations in a changing climate.

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

Published 23 September 2022 Presentations , Resources Closed
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Fifth symposium on the ocean in a high-CO2 world: the latest research on ocean acidification reviewed in Lima, Peru

Published 23 September 2022 Web sites and blogs Closed

The Fifth Symposium on the Ocean in a High-CO2 World, hosted by the Universidad Nacional Pedro Ruíz Gallo in Lima, Peru, from 13 to 16 September, convened close to 300 researchers from all over the world to discuss the latest findings in ocean acidification research.

This Symposium series, organized every four years, is the largest scientific multi-disciplinary gathering of researchers studying ocean acidification and its consequences, from field monitoring to laboratory experiments investigating impacts on biology and ecology, to modelling future scenarios and potential impacts on society.

Supported by the Prince Albert II of Monaco Foundation, this Fifth edition brought together more than 200 researchers attending in person and 90 participating online. Discussions were organized in six different themes and parallel sessions, with more than 170 presentations and 70 poster presentations.

Monaco hosted the Second Symposium in this Symposium series in 2008, leading to the publication of the Monaco declaration, signed by 155 scientists from 26 countries. At that time, ocean acidification was poorly known. Ever since, HSH Prince Albert II of Monaco has championed awareness raising around ocean acidification, bringing the issue to the attention of His fellow political leaders.

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Plastic degradation in the ocean contributes to its acidification

Published 22 September 2022 Press releases Closed
Graphical abstract. Credit: Science of The Total Environment (2022).

A new study led by the Institut de Ciències del Mar (ICM-CSIC) in Barcelona has revealed that plastic degradation contributes to ocean acidification via the release of dissolved organic carbon compounds from both the plastic itself and its additives.

“Thanks to this study we have been able to prove that in highly plastic-polluted ocean surface areas, plastic degradation will lead to a drop of up to 0.5 pH units, which is comparable to the pH drop estimated in the worst anthropogenic emissions scenarios for the end of the 21st century,” points out Cristina Romera-Castillo, ICM-CSIC researcher and first author of the study, which has been published this week in the journal Science of the Total Environment.

Acidification and plastic pollution are two of the major problems facing the ocean today. Since the industrial revolution, the increase in ocean acidity has made it more difficult for some calcifying organisms, such as corals, to maintain their skeletons. Every year up to 13 million tons of plastic reach the sea.

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Abiotic plastic leaching contributes to ocean acidification

Published 22 September 2022 Science Closed
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Graphical abstract.

Highlights

  • Abiotic plastic degradation induces a decrease in seawater pH.
  • The pH decrease is enhanced by solar radiation.
  • It is related to the amount of leached dissolved organic carbon.
  • It is probably induced from the release of organic acids and the production of CO2.
  • Plastic leaching could produce a seawater pH decrease up to 0.5 units.

Abstract

Ocean acidification and plastic pollution are considered as potential planetary boundary threats for which crossing certain thresholds could be very harmful for the world’s societies and ecosystems well-being. Surface oceans have acidified around 0.1 units since the Industrial Revolution, and the amount of plastic reaching the ocean in 2018 was quantified to 13 million metric tonnes. Currently, both ocean threats are worsening with time. Plastic leaching is known to alter the biogeochemistry of the ocean through the release of dissolved organic matter. However, its impact in the inorganic chemistry of the seawater is less studied. Here we show, from laboratory experiments, that abiotic plastic degradation induces a decrease in seawater pH, particularly if the plastic is already aged, as that found in the ocean. The pH decrease is enhanced by solar radiation, and it is probably induced from a combination of the release of organic acids and the production of CO2. It is also related to the amount of leached dissolved organic carbon, with higher acidification as leaching increases. In coastal areas, where plastic debris accumulates in large quantities, plastic leaching could lead to a seawater pH decrease up to 0.5 units. This is comparable to the projected decrease induced in surface oceans by the end of the twenty-first century for the most pessimistic anthropogenic emissions scenarios.

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Nano-ecotoxicology in a changing ocean

Published 22 September 2022 Science Closed
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Abstract

The ocean faces an era of change, driven in large by the release of anthropogenic CO2, and the unprecedented entry of pollutants into the water column. Nanomaterials, those particles < 100 nm, represent an emerging contaminant of environmental concern. Research on the ecotoxicology and fate of nanomaterials in the natural environment has increased substantially in recent years. However, commonly such research does not consider the wider environmental changes that are occurring in the ocean, i.e., ocean warming and acidification, and occurrence of co-contaminants. In this review, the current literature available on the combined impacts of nanomaterial exposure and (i) ocean warming, (ii) ocean acidification, (iii) co-contaminant stress, upon marine biota is explored. Here, it is identified that largely co-stressors influence nanomaterial ecotoxicity by altering their fate and behaviour in the water column, thus altering their bioavailability to marine organisms. By acting in this way, such stressors, are able to mitigate or elevate toxic effects of nanomaterials in a material-specific manner. However, current evidence is limited to a relatively small set of test materials and model organisms. Indeed, data is biased towards effects upon marine bivalve species. In future, expanding studies to involve other ecologically significant taxonomic groups, primarily marine phytoplankton will be highly beneficial. Although limited in number, the available evidence highlights the importance of considering co-occurring environmental changes in ecotoxicological research, as it is likely in the natural environment, the material of interest will not be the sole stressor encountered by biota. As such, research examining ecotoxicology alongside co-occurring environmental stressors is essential to effectively evaluating risk and develop effective long-term management strategies.

Article highlights

  • Ocean warming and acidification alter the fate and behaviour of nanomaterials, in turn altering their bioavailability and toxicity
  • Research is currently limited to a number of model materials and organisms
  • Consideration of environmental change is critical to long-term evaluation of pollutant risk in the natural environment
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Saving Nemo: extinction risk, conservation status, and effective management strategies for anemonefishes

Published 22 September 2022 Science Closed
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Anemonefishes share a number of life history and ecological traits, and some unfortunate links to human-induced stress, that expose some of the 28 species to the risk of extinction. The biodiversity hotspot for anemonefishes extends across Southeast Asia to the western Pacific, including many countries where there are high levels of human impact and few effective management strategies. Anemonefish biodiversity is threatened by anemone bleaching, direct effects of ocean warming and acidification, collection for the aquarium trade, and coastal development. These risks are exacerbated by extreme habitat specialization, the mutual anemonefish–anemone relationship, low abundance, low population connectivity, small geographic ranges, and shallow depth ranges. Many species exhibit two or three of these traits, with small range species often associated with fewer anemone hosts and narrower depth ranges, exposing them to double or triple jeopardy. While all species have not been assessed by the IUCN, our detailed analysis of area of occupancy indicates that three species are extremely close to the threshold for being classified as Critically Endangered. Marine reserves have been effective in protecting species from exploitation and helping sustain marginal populations across generations, but effective population sizes are often very small and recovery can be slow. Additional management efforts need to focus on sustainable collecting practices and the protection and restoration of critical anemone habitats.

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

Published 22 September 2022 Presentations , Resources Closed
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This is CDR ep.49: MRV for ocean-based CDR methods with Dr. Jessica Cross, NOAA (video & text)

Published 22 September 2022 Presentations , Resources Closed
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In this episode of This Is CDR, OpenAir welcomes NOAA Research Oceanographer Dr. Jessica Cross to discuss the challenges associated with measurement, reporting, and verification (MRV) of ocean-based CDR methods, and how we can seek to address them in a climate-relevant time-frame.

About our Guest. – https://www.pmel.noaa.gov/people/dr-j…

Dr. Jessica N. Cross is a research oceanographer with the NOAA in Seattle, WA. Her current research focuses on carbon biogeochemistry and ocean acidification in Arctic regions, and especially along the Alaskan coast. The main goal is to better understand how acidification processes interact with natural biogeochemical cycles, and eventually to detect geochemical and biological impacts of acidification in marine systems. Dr. Cross conducts her research across a variety of platforms, including ship-based measurements, moorings, and mobile autonomous platforms like gliders and drones, through NOAA’s Innovative Technology for Arctic Exploration Program. She also broadly participates in the Arctic research community through the North American Carbon Program, the Ocean Carbon Biogeochemistry Program, the Pacific Arctic Group, and the Interagency Research Policy Committee collaboration teams.

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Gregarious larval settlement mediates the responses of new recruits of the reef coral Acropora austera to ocean warming and acidification

Published 21 September 2022 Science Closed
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Gregarious larval settlement represents an important window for chimera formation in reef corals, yet it remains largely unknown how aggregated settlement and early chimerism could modify the performance and responses of coral recruits under elevated temperature and pCO2. In this study, single and aggregated recruits of the broadcast spawning coral Acropora austera were exposed to contrasts of two temperatures (28 versus 30.5°C) and pCO2 levels (~500 versus 1000 μatm) for two weeks, and algal symbiont infection success, survivorship and growth were assessed. Results showed that symbiont infection success was mainly affected by temperature and recruit type, with reduced symbiont infection at increased temperature and consistently higher infection success in chimeric recruits compared to single recruits. Furthermore, although chimeric recruits with larger areal size had significantly higher survivorship in all treatments, the polyp-specific growth rates were considerably lower in chimeric entities than individual recruits. More importantly, the recruit type significantly influenced the responses of recruit polyp-specific growth rates to elevated temperature, with chimeras exhibiting lowered skeletal lateral growth under elevated temperature. These results demonstrate the benefits and costs associated with gregarious larval settlement for juvenile corals under ocean warming and acidification, and highlight the ecological role of larval settlement behavior in mediating the responses of coral recruits to climate change stressors.

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An interactive planetary boundaries systems thinking learning tool to integrate sustainability into the chemistry curriculum

Published 21 September 2022 Science Closed
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Sustainability has a molecular basis that suggests a central role for chemistry in addressing today’s challenges to Earth and societal systems, and this role requires educators to see chemical reactions and processes as integral parts of dynamic and interconnected systems. Despite this prospect, few accessible resources are available for students and educators to facilitate systems thinking in chemistry for sustainability. We have developed an interactive digital learning tool (https://planetaryboundaries.kcvs.ca) based on the Planetary Boundaries framework, which uses interactive visualizations to help users better understand Earth system sustainability challenges and helps chemists and educators connect substances, reactions, and chemistry concepts to sustainability science. The tool highlights the fundamental role that chemistry plays in regulating the individual biophysical Earth system processes and in determining their control variables. It incorporates key features of a systems thinking framework by illustrating the dynamic interconnections among the processes and their control variables and demonstrates change of the Earth system over time. Finally, the interactive tool provides educators with accessible entry points to support the integration of chemistry curriculum content with sustainability considerations.

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Exposure to global change and microplastics elicits an immune response in an endangered coral

Published 21 September 2022 Science Closed
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Global change is increasing seawater temperatures and decreasing oceanic pH, driving declines of coral reefs globally. Coral ecosystems are also impacted by local stressors, including microplastics, which are ubiquitous on reefs. While the independent effects of these global and local stressors are well-documented, their interactions remain less explored. Here, we examine the independent and combined effects of global change (ocean warming and acidification) and microplastics exposures on gene expression (GE) and microbial community composition in the endangered coral Acropora cervicornis. Nine genotypes were fragmented and maintained in one of four experimental treatments: 1) ambient conditions (ambient seawater, no microplastics; AMB); 2) microplastics treatment (ambient seawater, microplastics; MP); 3) global change conditions (warm and acidic conditions, no microplastics; OAW); and 4) multistressor treatment (warm and acidic conditions with microplastics; OAW+MP) for 22 days, after which corals were sampled for genome-wide GE profiling and ITS and 16S metabarcoding. Overall A. cervicornis GE responses to all treatments were subtle; however, corals in the multistressor treatment exhibited the strongest GE responses, and genes associated with innate immunity were overrepresented in this treatment, according to gene ontology enrichment analyses. 16S analyses revealed stable microbiomes dominated by the bacterial associate Aquarickettsia, suggesting that these A. cervicornis fragments exhibited remarkably low variability in bacterial community composition. Future work should focus on functional differences across microbiomes, especially Aquarickettsia and viruses, in these responses. Overall, results suggest that local stressors present a unique challenge to endangered coral species under global change.

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Career opportunities: post-doctoral researcher

Published 21 September 2022 Jobs Closed

Apply before 30/09/2022

The Marine Biology Research group at UGENT is looking for a full-time (100%) Post-doctoral researcher to investigate benthic biogeochemistry and food webs in fjord environments

The fjords on the West Antarctic Peninsula (WAP) and Greenland experience among the most rapid and dramatic environmental changes in marine ecosystems, with substantial variation in the duration of the sea ice season, advanced glacier retreat, warming of surface waters and shifts in local primary production. Impacts of these changing ice conditions on the benthic ecosystem are complex, and mainly the effects on benthic carbon and nutrient cycling and food web resilience are poorly understood.

YOUR TASKS

This post-doc position will target fundamental research on the impact of changing ice conditions on benthic biogeochemistry and food webs in two polar environments. The successful candidate will participate in research cruises to the west-Antarctic Peninsula and Greenland, collect and process sediment samples, perform biogeochemical measurements and identify benthic communities. The post-doctoral researcher will be engaged in the interdisciplinary research project TANGO (‘Estimating Tipping points in habitability of ANtarctic benthic ecosystems under GlObal future climate change scenarios’) and CANOE (‘Climate chANge impacts on carbon cycling and fOod wEbs in Arctic fjords’). Both projects aim to investigate biogeochemistry and food web structure and stability, in response to declining sea ice conditions (TANGO) and to glacial melt on in Greenlandic fjords (CANOE).

We seek a candidate with a background in marine science, biogeochemistry, biology, or related fields.
The selected candidate will work in the group of Prof. Vanreusel and Prof. Ulrike Braeckman.

  • You are highly motivated to conduct research within an international and interdisciplinary team of researchers, and thus build a professional network and academic career;
  • You will perform fundamental research within the domain of marine biogeochemistry and (food web) ecology;  
  • You prepare and participate regularly in sampling campaigns at sea on location in Antarctic and (sub-)Arctic fjords with lengths of a few days to a few months.
  • You have a strong interest in marine biogeochemistry and ecology;
  • You will support education activities at Ghent University by supervising bachelor and master thesis projects, and by assisting in practical and theoretical biology and ecology classes;
  • You will process the data and communicate the results into one or more scientific papers.


INTERESTED?

Apply online through the e-recruitment system before the application deadline (see above). We do not accept late applications or applications that are not submitted through the online system. We will perform a pre-selection and invite selected candidates for an interview. The selection committee will review the applications immediately after the application deadline. The interviews will take place at the end of September.

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

Published 21 September 2022 Presentations , Resources Closed
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The effects of ocean acidification on the establishment and maintenance of a model cnidarian-dinoflagellate symbiosis

Published 20 September 2022 Science Closed
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Coral reefs are increasingly under threat from the effects of anthropogenic climate change, including rising sea surface temperatures and more acidified waters. At the foundation of these diverse and valuable ecosystems is the symbiotic relationship between calcifying corals and their endosymbiotic dinoflagellate algae, Symbiodiniaceae – one that is particularly sensitive to environmental stressors. Ocean acidification (OA) results in the lowering of pH and changes to carbonate chemistry and the inorganic carbon species available to marine organisms. Cnidarians such as reef-building corals may be particularly at risk from OA, as changes in pH and carbon availability can alter central physiological processes, including calcification, photosynthesis, acid-base regulation, metabolism and cell-cycle regulation. Yet, while responses to OA have been well researched at the physiological level, results have often been contradictory, and a clear understanding of the nature and extent of impacts on the cnidarian-dinoflagellate symbiosis remains equivocal. This thesis therefore aimed to provide further insights into the effects of OA on the establishment and maintenance of the cnidarian-dinoflagellate symbiosis. My research utilised the well-established model system for this symbiosis: the sea anemone Exaiptasia diaphana (‘Aiptasia’) and its native symbiont Breviolum minutum.

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How does CO2-induced acidification affect post-ecydsial exoskeletal mineralization in the blue crab, Callinectes sapidus?

Published 20 September 2022 Science Closed
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Carbon dioxide (CO2) enrichment in seawater because of increased use of fossil fuels can possibly cause detrimental effects on the physiological processes of marine life, especially shell builders, due to CO2-induced ocean acidification. We investigated, for the first time, specifically the effect of CO2 enrichment on post-ecydsial shell mineralization in Crustacea using the blue crab, Callinectes sapidus, as the model crustacean. It was hypothesized that CO2 enrichment of seawater would adversely affect exoskeletal mineralization in the blue crab. This experiment used two groups of post-ecydsial crabs, with one group exposed to seawater at a pH of 8.20 and the other group treated with CO2-acidified seawater with a pH of 7.80 – 7.90. After a period of 7 days, samples of exoskeleton and hemolymph were collected from the survivors. CO2 enrichment was found to significantly increase exoskeletal magnesium content by 104% relative to control, while a statistically non-significant elevation of 31% in exoskeletal calcium was registered. Because CO2 treatment did not change the content of magnesium and calcium in the hemolymph, we postulate herein that increased exoskeletal mineralization in post-ecydsial blue crabs must stem from an increased influx of bicarbonate ions from the medium through the gill, to the hemolymph, and across the epidermis. Additionally, the observed significant increase in the mass of exoskeleton following CO2 treatment must be at least partly accounted for by enhanced postmolt carbonate salt deposition to the shell.

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Global change differentially modulates Caribbean coral physiology

Published 20 September 2022 Science Closed
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Global change driven by anthropogenic carbon emissions is altering ecosystems at unprecedented rates, especially coral reefs, whose symbiosis with algal symbionts is particularly vulnerable to increasing ocean temperatures and altered carbonate chemistry. Here, we assess the physiological responses of three Caribbean coral (animal host + algal symbiont) species from an inshore and offshore reef environment after exposure to simulated ocean warming (28, 31°C), acidification (300–3290 μatm), and the combination of stressors for 93 days. We used multidimensional analyses to assess how a variety of coral physiological parameters respond to ocean acidification and warming. Our results demonstrate reductions in coral health in Siderastrea siderea and Porites astreoides in response to projected ocean acidification, while future warming elicited severe declines in Pseudodiploria strigosa. Offshore S. siderea fragments exhibited higher physiological plasticity than inshore counterparts, suggesting that this offshore population was more susceptible to changing conditions. There were no plasticity differences in P. strigosa and P. astreoides between natal reef environments, however, temperature evoked stronger responses in both species. Interestingly, while each species exhibited unique physiological responses to ocean acidification and warming, when data from all three species are modelled together, convergent stress responses to these conditions are observed, highlighting the overall sensitivities of tropical corals to these stressors. Our results demonstrate that while ocean warming is a severe acute stressor that will have dire consequences for coral reefs globally, chronic exposure to acidification may also impact coral physiology to a greater extent in some species than previously assumed. Further, our study identifies S. siderea and P. astreoides as potential ‘winners’ on future Caribbean coral reefs due to their resilience under projected global change stressors, while P. strigosa will likely be a ‘loser’ due to their sensitivity to thermal stress events. Together, these species-specific responses to global change we observe will likely manifest in altered Caribbean reef assemblages in the future.

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