Archive for the 'Press releases' Category

New study finds ocean acidification and warming hinder juvenile Atlantic sea scallop growth

Small marine animals called sea scallops with two light brown rounded shells and numerous blue eyes along the shell margins sit in clear seawater on the mesh bottom of an aquarium. Juvenile sea scallops obtained from ​​Pine Point Oyster Company in Maine were used in this ocean acidification exposure study.

new study published in PLOS Climate indicates that ocean acidification conditions projected between now and 2100 depress the growth of juvenile Atlantic sea scallopsOcean acidification is caused by the ocean absorbing carbon dioxide from the atmosphere, resulting in chemical changes that increase acidity. Ocean warming may further hinder growth. Atlantic sea scallops support one of the most valuable fisheries in the United States, worth $670 million in 2021.

Postdoctoral researcher and lead author Emilien Pousse said, “This work describes the energetic balance of sea scallops under ocean acidification conditions for the first time, a species of economic and socio-cultural importance. Within our changing world, getting to know how our marine resources and fisheries could be affected by ocean warming and acidification in the near future is the key to anticipate the upcoming changes.”

The 8-week study was a collaboration between NOAA Fisheries and Massachusetts Maritime Academy in Buzzards Bay, Massachusetts. Faculty and students helped NOAA scientists conduct the study at the campus’ aquaculture lab. Scientists exposed the scallops to three different carbon dioxide levels and measured their growth and metabolism, including feeding, respiration, and excretion rates. Ocean acidification conditions significantly reduced the scallops’ ability to take up energy.

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A universal framework to measure the impacts of ocean acidification on marine life

IOC/UNESCO’s efforts to advance towards the Sustainable Development Goal 14.3 “Minimize and address the impacts of ocean acidification, including through enhanced scientific cooperation at all levels’ involve its role as the custodian agency for the associated indicator 14.3.1, meaning that it is responsible for the compilation and sharing of global data on ocean acidification.

Ocean acidification is a significant environmental threat that is having a profound impact on marine life, including coral reefs, shellfish, and many other species. A lack of a global framework for measuring the effects of ocean acidification on marine life has made it difficult for the scientific community to effectively assess this issue.  

The publication of the new article “Unifying biological field observations to detect and compare ocean acidification impacts across marine species and ecosystems: What to monitor and why” by the GOA-ON Biological Working Group, supported by IOC/UNESCO, provides a global guiding framework for the scientific community to measure the impacts of ocean acidification on marine life.  It  proposes five broad classes of biological indicators that, when coupled with environmental observations including carbonate chemistry, would allow to observe and compare the rate and severity of biological change in response to ocean acidification globally. 

Such a novel observing methodology allows inclusion of a wide diversity of marine ecosystems in regional and global assessments and has the potential to increase the contribution of ocean acidification observations from countries with developing ocean acidification science capacity.

Read the paper online: 

IOC-UNESCO, 31 January 2023. Press release.

Vulnerability of red sea urchins to climate change depends on location

Red sea urchins are an important commercial fishery species along the California coast. Emily Donham and other UCSC researchers studied how different populations of red sea urchins respond to changes in their environments. (Photo by Kate Vylet)

A new study of red sea urchins, a commercially valuable species, investigated how different populations respond to changes in their environments. The results show that red sea urchin populations in Northern and Southern California are adapted to their local conditions but differ in their vulnerability to the environmental changes expected to occur in the future due to global climate change and ocean acidification.

The new findings, published January 20 in Science Advances, indicate that red sea urchin populations in Southern California may be more vulnerable to climate change than those in Northern California. Although the sea urchins in Southern California are already adapted to warmer conditions, the researchers suspect that further warming of their environment may be more than they can tolerate.

“Red sea urchins from the Southern California population were much more sensitive to environmental changes than those from Northern California, and we think that is likely because they are already closer to some kind of thermal limit,” said senior author Kristy Kroeker, professor of ecology and evolutionary biology at UC Santa Cruz.

First author Emily Donham led the study as a UCSC graduate student and is now a postdoctoral scholar at UC Santa Barbara. “Red sea urchins are an important fishery species along our coast, so understanding how they are likely to be impacted by climate change is very important,” she said.

The study looked at the effects of three key environmental variables in the sea urchins’ coastal habitat: water temperature, dissolved oxygen, and pH (a measure of ocean acidification). Climate change driven by increased carbon dioxide in the atmosphere is warming the oceans and reducing oxygen levels in the water, while increased absorption of carbon dioxide by seawater leads to ocean acidification.

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Increased ocean warming leads to population shift of plankton

Increasing concentration of CO2 and global warming could lead to a shift of the dominant plankton population in the ocean, intriguing new research shows. If CO2 emissions into the atmosphere remain high until the year 2100, a different type of plankton will become the dominant species in the North Atlantic Ocean. This shift in plankton populations will also have an additional negative effect as less carbon will be stored in the deep ocean waters. As result, more of the emitted CO2 will remain in the atmosphere, Amber Boot, Anna von der Heydt and Henk Dijkstra (NESSC/IMAU) illustrate in a paper published today in Geophysical Research Letters.

Plankton – the collective name for a wide range of different organisms living in ocean waters – plays an important role in removing carbon from the atmosphere and storing it for thousands of years in the deep waters of the ocean. This biological process counteracts and slows down the still increasing concentration of CO2 in the earth’s atmosphere. However, the production of plankton and the speed of carbon sequestration are linked to different conditions which can be influenced by the concentration of CO2 in the atmosphere.

Curious to learn how increasing CO2 can influence this important process, PhD candidate Amber Boot modeled the response of the oceans to a steeply increasing concentration of CO2 in the atmosphere until the year 2100. Results of this high CO2 scenario indicate that at the end of this century the most dominant plankton type in the North Atlantic Ocean will disappear and be replaced by a different plankton population. This type of plankton, however, has a lower efficiency in removing carbon from the surface ocean, thereby reducing the capacity of the ocean to uptake carbon. The shift in plankton population would also result in a higher concentration of CO2 in the atmosphere, enhancing further climate change.

Effect of Plankton Composition Shifts in the North Atlantic on Atmospheric pCO2, Amber Boot, Anna. S. von der Heydt, and Henk A. Dijkstra, Geophysical Research Letters, 49, 2022, DOI 10.1029/2022GL100230.

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Increase in marine heatwaves expected to affect organisms at bottom of food chain, study suggests

Larvae of the Atlantic mangrove fiddler crab (Leptuca thayeri, left) survived less in warmer water and underwent physiological changes due to higher acidity. Credit: Murilo Marochi.

An increase in marine heatwaves due to global climate change in the coming decades will have a significant impact on lifeforms in this environment, including those at the bottom of the food chain, according to a paper published in Estuarine, Coastal and Shelf Science by Brazilian researchers working in Brazil, Norway and the United States,

Marine heatwaves are periods of more than five days with water temperatures more than 90% above the historical average for the region. Projections point to a rise of 35% in the frequency of marine heatwaves by the year 2100 for the Santos-São Vicente area (coast of São Paulo state, Brazil) in which the study reported by the paper was conducted. It is important to distinguish between marine and atmospheric heatwaves, the latter typically being more intense but affecting mainly terrestrial environments, including cities.

The researchers evaluated the potential impact of marine heatwaves on planktonic larvae of the Atlantic mangrove fiddler crab Leptuca thayeri. “Although the larvae survived a rise in the acidity of the water, a rise of 2 °C in sea surface temperature during the first three to four days of their lives led to a 15% drop in the survival rate compared with larvae at the average temperature for the region. A rise of 4 °C led to a 34% rise in mortality,” said Murilo Zanetti Marochi, first author of the paper. The study was conducted while he was on a postdoctoral research fellowship at the Institute of Biosciences of the São Paulo State University’s Coast Campus (IB-CLP-UNESP) in São Vicente.

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Malformed seashells, ancient sediment provide clues about Earth’s past

Scanning electron microscope images of tiny, malformed planktonic seashells. Credit: Gabby Kitch

Nearly 100 million years ago, the Earth experienced an extreme environmental disruption that choked oxygen from the oceans and led to elevated marine extinction levels that affected the entire globe. 

Now, in a pair of complementary new studies, two Northwestern University-led teams of geoscientists report new findings on the chronology and character of events that led to this occurrence, known as Ocean Anoxic Event 2 (OAE2), which was co-discovered more than 40 years ago by late Northwestern professor Seymour Schlanger. 

By studying preserved planktonic microfossils and bulk sediment extracted from three sites around the world, the team collected direct evidence indicating that ocean acidification occurred during the earliest stages of the event, due to carbon dioxide (CO2) emissions from the eruption of massive volcanic complexes on the sea floor.

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Scientists stress the need to drastically reduce CO2 emissions by 2030 to avoid crossing irreversible thresholds for frozen Earth

A recent comment piece in Nature Climate Change, involving eleven scientists from 7 countries, expresses the desperate need for a significant reduction in CO2 emissions if we are to protect the cryosphere, a term used to encapsulate the frozen areas of this planet.
Cryosphere habitats, such as Arctic sea ice, glaciers across the world, ice sheets in Greenland and Antarctica, and permafrost have experienced losses through melting over the last several decades as a result of climate change but sadly, that is just the tip of the iceberg.
The cryosphere is particularly vulnerable to climate change mainly due to the risk of crossing abrupt and/or irreversible thresholds, often called tipping points. ‘Abrupt’ in this case means a much faster change than usual for that system, while irreversibility depends on the timescale at which a system can recover to its previous state.
Limiting emission, and therefore warming, in line with the Paris Agreement might still suffice to avoid passing multiple thresholds, including those of melting the Greenland and Antarctic ice sheets, and boreal permafrost thaw. However the precise nature of the Earth system thresholds is subject to considerable uncertainties.
Following the Intergovernmental Panel on Climate Change (IPCC) 6th report, risks rapidly escalate above 1.5°C and even more so if 2°C is exceeded. Exceeding 3°C would almost certainly trigger ice sheet instability, as well as cause widespread ocean acidification resulting in episodes that would corrode carbonate minerals, which are used to form shells and skeletons by some key marine animals.
Polar ocean acidification is approaching a chemical threshold within the coming decades. At 1.5-2°C warming, Arctic waters will be corrosive to important minerals for several months of the year, with the Southern Ocean following at 2-3°C warming. It will take tens of thousands of years to reverse due to the very slow ocean processes involved. The good news is that limiting warming to 1.5°C can avoid the worst of these impacts.

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Marine animals able to cope with ocean acidification through epigenetic changes

Marine animals able to cope with ocean acidification through epigenetic changes
Credit: Nature Climate Change (2022). DOI: 10.1038/s41558-022-01477-4

International research co-authored by scientists at the Education University of Hong Kong (EdUHK) found that a major type of marine species can adapt to ocean acidification. Considered a major breakthrough in marine biology research, the findings were recently published in the journal Nature Climate Change.

As our planet is witnessing an ever-increasing level of carbon dioxide emissions, the threat of ocean acidity has become all the more acute. To examine the long-term effects of ocean acidification on biodiversity and the food chain, seven scholars from South Korea, mainland China, Hong Kong, and the United States carried out a two-year study on the reproduction of marine species in an acidified environment.

One member of the research team was Professor Rudolf Wu Shiu-sun, Advisor (Environmental Science) in the Department of Science and Environmental Studies at EdUHK, who was responsible for relating the phenotypic and epigenetic changes among marine organisms, and explaining the relevant environmental implications of the study.

The team chose as its research subject copepods, one of the most abundant classes of zooplankton, which plays a key role in the food chain in the marine environment. To mimic ocean acidification, copepods were placed in water with increasing acidity (pH 8.0, pH 7.7 and pH 7.3) to evaluate the impact of acidification on their ability to reproduce.

The results showed that in an acidified environment, the fertility and sex ratio of copepods were adversely affected in the first and second generations (F0 and F1), but were significantly restored in the third generation (F2). This suggests that copepods have a self-repairing ability to adapt to environmental change.

More information: Young Hwan Lee et al, Epigenetic plasticity enables copepods to cope with ocean acidification, Nature Climate Change (2022). DOI: 10.1038/s41558-022-01477-4

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Experts urge COP15 policy makers to support research to find, catalogue, protect disappearing deep-sea species

Global marine experts urge COP15 policy-makers to support research to find, catalogue, protect disappearing deep-sea species

More than 90% of marine species are undescribed and many may go extinct due to human activity before they’re discovered—the loss of unique, potentially valuable genetic resources resulting in unpredictable effects on global ecosystems essential to human food supplies and climate regulation.

Without knowledge of these species, effective deep sea conservation is impossible, leading international marine scientists warned in a new policy brief presented at the UN Biodiversity Conference (COP15) today in Montreal.

They urge global policy-makers to support urgently needed new research to fill a critical knowledge gap.

While roughly 28,000 deep-sea animal species have been described and named, an estimated 2.2 million other marine species, including deep-sea, are unknown to science, of which many are thought to be threatened with extinction.

In 2019, the Scaly-foot Snail (Chrysomallon squamiferum) became the first deep-sea species listed as globally endangered due to the threat of deep-seabed mining.

“Conservation of deep-sea species found in ‘areas beyond national jurisdiction’ is particularly challenging,” the policy brief says.

“We know very little about them, and there is not yet an international framework to guide the implementation of conservation measures,” says lead author of the brief, Dr. Stefanie Kaiser of the Senckenberg Research Institute and Natural History Museum, Frankfurt.

Knowledge of deep-sea species biodiversity is an obvious first step to effective protection of both the species and the ecosystem processes associated with them.

The scientists warn that deep sea species are increasingly exposed to pollution and habitat destruction.

In particular, global warmingocean acidification and resource depletion could lead to dramatic changes in deep-sea biodiversity with unpredictable consequences for humans as well.

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Eckerd College professor publishes paper on sharing research about health of Florida stone crabs

Assistant Professor of Marine Science Philip Gravinese works with students to study stone crabs in Tampa Bay.

The way Philip Gravinese, Ph.D., sees it, research is important not just for what can be discovered but for how that information can be shared.

In keeping with that philosophy, Gravinese, an Eckerd College assistant professor of marine science, recently co-authored a paper titled “Do pH-Variable Habitats Provide Refuge for Stone Crabs from Coastal Acidification?” It was published Nov. 15 in the journal Oceanography.

“The paper is a lesson developed for educators that is based on some of the ongoing research I’ve been doing near Fort De Soto Park,” Gravinese explains. “In this work we are looking at stone crab reproductive success between sandy habitats (narrow pH range) and seagrass habitats (wider pH range) to see if the pH range between those habitats provides the stone crab with any reproductive advantage under future climate change reductions in seawater pH.”

The project is being funded by the Tampa Bay Estuary Program.

Last year, Gravinese and two researchers from Louisiana State University were awarded a four-year, $922,000 grant from the National Science Foundation to study the impact of climate change on stone crabs. The goal is to investigate and model how rapidly changing ocean temperatures and pH levels disrupt stone crab larval development, behavior and dispersal among habitats along the Florida coasts. Gravinese’s previous work has shown that stone crabs can be sensitive to environmental stressors throughout their larval development.

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Engineered nanoparticles could help store excess carbon dioxide in the ocean

Seeding the oceans with nano-scale fertilizers could create a much-needed, substantial carbon sink. Credit: Stephanie King | Pacific Northwest National Laboratory

The urgent need to remove excess carbon dioxide from Earth’s environment could include enlisting some of our planet’s smallest inhabitants, according to an international research team led by Michael Hochella of the Department of Energy’s Pacific Northwest National Laboratory.

Hochella and his colleagues examined the scientific evidence for seeding the oceans with iron-rich engineered fertilizer particles near ocean plankton. The goal would be to feed phytoplankton, microscopic plants that are a key part of the ocean ecosystem, to encourage growth and carbon dioxide (CO2) uptake. The analysis article appears in the journal Nature Nanotechnology.

“The idea is to augment existing processes,” said Hochella, a Laboratory fellow at Pacific Northwest National Laboratory. “Humans have fertilized the land to grow crops for centuries. We can learn to fertilize the oceans responsibly.”

In nature, nutrients from the land reach oceans through rivers and blowing dust to fertilize plankton. The research team proposes moving this natural process one step further to help remove excess CO2 through the ocean. They studied evidence that suggests adding specific combinations of carefully engineered materials could effectively fertilize the oceans, encouraging phytoplankton to act as a carbon sink.

More information: Peyman Babakhani et al, Potential use of engineered nanoparticles in ocean fertilization for large-scale atmospheric carbon dioxide removal, Nature Nanotechnology (2022). DOI: 10.1038/s41565-022-01226-w

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Calcifying organisms, under threat from a combination of ocean warming and acidification

Newswise: Calcifying organisms, under threat from a combination of ocean warming and acidification

A bryozoan, at 32m depth at Signy Island, Antarctica. Credit: David Barnes, British Antarctic Survey

A new study led by the Institut de Ciències del Mar (ICM-CSIC), with colleagues from the British Antarctic Survey, the Institute of Oceanology, the Polish Academy of Sciences and the University of Gdańsk have also participated has revealed that global warming and ocean acidification threaten marine organisms that build their skeletons and shells with calcium carbonate (chalk) such as corals, bryozoans, molluscs, sea urchins or crustaceans.

The work, recently published in the journal Ecography, focuses on organisms with calcium carbonate skeletons from around Antarctica in the Southern Ocean. Calcium carbonate is more soluble in more acidic waters which contain more carbon dioxide (CO2), such as the colder waters of the polar regions, making it harder for these creatures to build their skeletons.

Bryozoans, key for understanding the global change impacts on calcifying organisms

To carry out the study, researchers analysed the skeleton of a group of marine creatures called bryozoans (commonly known as moss animals), which are small filter-feeding invertebrates that live on the seafloor and can create complex habitats that enhance biodiversity.

In this sense, the expert explains that the bryozoan skeletons are made of the two main types of calcium carbonate, calcite or aragonite, but they can also incorporate magnesium, which can make the skeletons more vulnerable to acidification.

Through mineralogical analyses, researchers identified the different types of minerals and determined the levels of magnesium found in Antarctic bryozoan skeletons, creating the largest dataset for Southern Ocean bryozoans ever produced. Then, they included these mineral signatures with existing data from almost 500 species found in the Southern Hemisphere and compared the distribution of the different mineral types and levels of magnesium in their skeletons with the temperature of the seawater that they lived in.

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Ocean warming and acidification impact the marine food web, study finds

Ocean warming and acidification impact marine food web
(A) A healthy coccolithophore. (B) A collapsed coccolithophore. Ocean acidification greatly increases the chance of the coccolithophore sphere to collapse. Credit: Roberta Johnson ICTA-UAB

Ocean warming and ocean acidification driven by climate change decrease the nutritional quality of some marine organisms, causing disruptions to the ocean food web.

This is the main conclusion of a study conducted by the Institute of Environmental Science and Technology of the Universitat Autònoma de Barcelona (ICTA-UAB) in collaboration with the Roscoff Marine Station (France) that analyzes the increase in temperature and ocean acidification on the nutritional content of coccolithophores, a unique and abundant type of phytoplankton able to calcify and cover the cell with elaborate calcite elements.

Ocean warming and acidification are the result of the rapid accumulation of carbon dioxide in the atmosphere. While ocean warming is predicted to cause changes in the distribution of species, which will have impacts on marine ecosystems, calcifying marine organisms are predicted to respond negatively to ocean acidification as it makes it more difficult for them to build their skeleton or shells. Although these impacts are expected to affect the marine food web, there is a lack of knowledge as to what these specific effects will be.

Coccolithophores are at the base of the marine food web and are a food source for many zooplankton species by providing energy to these organisms in the form of fats (lipids) and other nutrients. Like other marine organisms, acidification is expected to negatively affect their shells.

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Launch of State of the Climate 2022 report

The Minister for Science and Industry Ed Husic and the Minister for the Environment and Water Tanya Plibersek today launched the State of the Climate Report 2022.

The report underlines why the Australian Government is acting with urgency to tackle climate change in line with our international obligations and the expectations of the Australian people.

It was prepared by two of Australia’s leading climate research agencies, the CSIRO and the Bureau of Meteorology.

State of the Climate has found changes to weather and climate extremes are happening at an increased pace across Australia.

The report, released every two years, shows an increase in extreme heat events, intense heavy rainfall, longer fire seasons and sea level rise. The report draws on the latest climate monitoring, science and projection information to detail Australia’s changing climate now and into the future. 

The report details that concentrations of greenhouse gases, such as carbon dioxide, are at the highest levels seen on Earth in at least two million years. This is causing Australia’s climate to warm. 

The report also documents the continuing acidification of the oceans around Australia, which have also warmed by more than one degree since 1900.  

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Warmer climate causing acidification of the Arctic Ocean

As early as the expedition in 2014 with the icebreaker Oden, the researchers could see that the sea ice coverage was greatly reduced in the Arctic. Photo: Jorien Vonk

By comparing data from a long list of Arctic expeditions, researchers have been able to see how the pH of the ocean north of Alaska and Siberia has decreased rapidly. In recent decades, the rate of acidification of the Arctic Ocean has been 3–4 times faster than in other oceans. This is because more carbon dioxide is taken up by the sea water when the surface is in direct contact with the atmosphere without a barrier of ice. In the past, the sea ice has kept the sea water close to the North Pole from being saturated with carbon dioxide.

“The time-series of pH measurements made in the Arctic Ocean is long. The oldest are from an expedition in 1994, when the ice sheet was extensive and thick, and measurements were taken in the leads between the ice floes. On the expedition in 2014, the icebreaker Oden was able to travel in open water half way from Siberia to the North Pole,” says Leif Anderson, researcher in marine chemistry at the University of Gothenburg and one of the authors of the study.

The measured acidification over the last 30 years corresponds to about 0.1 on the pH scale. The researchers estimate that the pH value will decrease a further 0.3 by the next turn of the century if carbon dioxide levels continue to rise in the atmosphere as they are today. The impact will be greatest in the coldest oceans. Water temperature determines how much carbon dioxide can be dissolved in the ocean. More freshwater from melted sea ice also result in a larger acidification effect by the uptake of carbon dioxide from the atmosphere due to changes in the seawater chemistry.

Article in Science: Climate change drives rapid decadal acidification in the Arctic Ocean from 1994 to 2020

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Tracing anthropogenically emitted carbon dioxide into the ocean

The net atmosphere-to-ocean carbon flow rates for total carbon (and hence for ΔC), anthropogenically

Through fossil fuel combustion, deforestation, and other industrial and agricultural activities, humans have raised global atmospheric carbon dioxide (CO2) levels to more than 415 parts per million. That concentration represents a 135-parts-per-million increase since preindustrial times in the late 18th century. It is often assumed that this CO2 increase consists entirely of anthropogenically emitted CO2, but a new study challenges that assumption.

To investigate the standard narrative about the fate of anthropogenically emitted carbon, Holzer and DeVries labeled CO2 as it was emitted and tracked it with a data-assimilated ocean circulation model. This method allowed them to partition the net changes in atmospheric and oceanic carbon inventories as either anthropogenically emitted or natural carbon. The model followed the journey of emitted carbon from 1780 to 2020 using what is called a linear labeling tracer. Researchers have used this labeling technique in other applications but never to track anthropogenic carbon.

The modeling revealed that only 45% of the increase in atmospheric carbon over the past few centuries originated as emitted carbon and that outgassed natural carbon from the ocean accounts for the other 55%. The researchers also found that the ocean has accumulated nearly twice as much emitted carbon as previously assumed.

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50% of Earth’s coral reefs face climate change threat by 2035

Under a worst-case scenario, half of coral reef ecosystems worldwide will permanently face unsuitable conditions in just over a dozen years, if climate change continues unabated. That is one of the findings from new research published on October 11, in PLOS Biology by University of Hawaiʻi at Mānoa researchers. Unsuitable conditions will likely lead to the corals dying off and other marine life will struggle to survive due to disruptions in the food chain.

“While the negative impacts of climate change on coral reefs are well known, this research shows that they are actually worse than anticipated due to a broad combination of climate change-induced stressors,” said lead author Renee O. Setter, a doctoral student in the Department of Geography and Environment in the College of Social Sciences. “It was surprising to find that so many global coral reefs would be overwhelmed by unsuitable environmental conditions so soon due to multiple stressors.”

Using an ensemble of global climate change models, the researchers compared scenarios of five environmental stressors projected from the 1950s through the year 2100. These stressors included sea surface temperature, ocean acidification, tropical storms, land use and human population. From prior studies, threshold values for the stressors that led to unsuitable environmental conditions for coral reefs were identified.

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Incorporating traditional management techniques to combat effects of ocean acidification

Robotirator that is used to measure alkalinity of the water. Image courtesy of Hannah Hensel.

Ocean acidification is a major concern related to climate change, with the oceans currently absorbing around a quarter of the carbon dioxide that is released into the atmosphere. The increased CO 2 that is absorbed by the ocean in turn decreases its pH, making the waters more acidic. These more acidic conditions put marine organisms that create calcium carbonate shells and skeletons at risk.

New research that will be presented Monday at the Geological Society of America’s GSA Connects 2022 meeting evaluated a strategy based on Indigenous techniques that may help to mitigate the effects of ocean acidification on calcifying organisms.

Hannah Hensel, a Ph.D. candidate at the University of California, Davis, led a study that tested whether adding shell hash—pulverized clam shells—to sediments could help raise the pH of pore waters and aid in calcification for infaunal marine organisms.

“One of the things that marine invertebrates have to deal with regarding climate change is ocean acidification,” said Hensel. “When researching marine invertebrates that build shells and skeletons out of calcium carbonate, I came upon some research by a diverse group of people up in British Columbia working in clam gardens, an Indigenous shellfish management practice.”

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Arctic Ocean: greater future acidification in summer

The ‘Roaring Forties’ (Photo: Frank Rödel)

Over the past 200 years, our planet’s oceans have absorbed more than a quarter of all anthropogenic carbon dioxide from the atmosphere. As a result, their acidity has increased by nearly 30 percent their acidity has increased by nearly 30 percent since the beginning of the Industrial Revolution. In this regard, the water’s pH value isn’t constant; it varies both seasonally and regionally. The lowest values naturally occur in winter. But that could soon change, since they could be shifted to the summer by climate change, as an international team including experts from the Alfred Wegener Institute recently demonstrated. If this comes to pass, it could have far-reaching consequences for life in the ocean, as they report in the journal Nature.

The biological activity of marine organisms normally reaches its zenith in summer, as the season is normally characterised by optimal conditions for survival, finding food and reproducing. However, climate change is now threatening this status quo by shifting the point at which the pH values are lowest from winter to summer, as experts from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) and France’s Laboratory for Sciences of Climate and Environment (LSCE, part of the CEA); LOCEAN – Laboratory of Oceanography and Climatology; and Institute Pierre-Simon Laplace (IPSL) recently determined. In a new study, they conclude that summer acidification could intensify by up to 25 percent by the end of the century. Some organisms living in the Arctic Ocean would be severely affected by this change, reducing their ability to cope with more intensive summertime warming.

This seasonal shift is due to the more intense rise in CO2 in warmer water. In summer, atmospheric temperatures rise in the Arctic, more sea ice melts, and the surface water grows warmer. This warming process becomes so intense that the acidification of the seawater increases much more rapidly and can no longer be compensated for by the photosynthesis of marine algae. “These new findings spell trouble for some types of Arctic fish, like the polar cod, which are already threatened by climate change,” says co-author Hans-Otto Pörtner, a biologist and climate researcher at the AWI. “The projected high temperatures will push Arctic fauna to their thermal limits or even beyond, particularly with regard to life stages in which they’re more fragile.” First author James Orr from the LSCE and IPSL adds: “Who would have thought that climate change could shift the time of maximum acidification by six months, when studies on seasonal biological rhythms only projected shifts of up to roughly a month?” “The fascinating thing about this study is the fact that the chemical winters will actually become chemical summers,” says Lester Kwiatkowski, a co-author from LOCEAN and the IPSL.

In their study, the experts analysed simulations of 27 Earth system models and prepared future climate scenarios. While doing so, for the first time they assessed the potential for seasonal shifts in acidification, including all related variables. Why? Because the degree of acidification isn’t determined by just one factor; it’s a complex interplay of physical and biological processes, influenced by the more intense warming of surface water in summer. These changes were more pronounced in scenarios with moderate and high greenhouse-gas emissions and were far milder in those with lower emissions. In the researchers’ eyes, this represents a glimmer of hope that key elements of the Arctic Ocean’s ecosystem can be preserved if mean global warming can be kept below 2°C.

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Climate risks for Gulf of Mexico coral reefs spelled out in study

The Flower Garden Banks National Marine Sanctuary about 100 miles offshore from Texas and Louisiana is home to some of the healthiest coral reefs in the United States. (Photo by G.P. Schmahl/NOAA)

Ocean temperatures in the Gulf of Mexico and the Caribbean Sea are on pace to surpass critical thresholds for coral health by mid-century, but rapid action to significantly reduce emissions could slow warming, giving corals and coral conservation programs as much as 20 more years to adapt, according to new research.

Climate scientists and marine biologists from Rice University, the University of Colorado Boulder and Louisiana State University used computer models to simulate climate warming from 2015-2100 under both a “business as usual” scenario with very high emissions and a scenario in which emissions were reduced to high levels. Their study and analysis of ocean warming and ocean acidification levels for specific regions in the Gulf of Mexico and Caribbean under each scenario is published in the Journal of Geophysical Research: Biogeosciences. The researchers found reducing emissions could delay the onset of critically warm ocean temperatures in some areas where reefs are still healthy.

“There are reefs in the Gulf that are really worth saving,” said Rice University marine biologist Adrienne Correa, a co-author of the study. “Some of the healthiest reefs that we still have in the United States are in the areas covered by these projections.”

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