The once common kelp forests and abalone fisheries of the Shikine Island in Japan have now vanished. Scientists from Japan identified that these temperate coastal marine ecosystems are transforming into much “simpler” ones, deprived of their biodiversity aesthetic values and complexity.

Researchers from the University of Tsukuba find that the combined effects of ocean warming and acidification in temperate marine ecosystems are resulting in a loss of kelp habitat and a shift to a simple turf-dominated ecosystem. Such changes will lead to a loss of the ecosystem services provided by productive macroalgal forests or tropicalized coral-dominated reefs. These results highlight the need for reductions in greenhouse gas emissions. Image Credit: University of Tsukuba.

Scientists from the University of Tsukuba along with their international collaborators investigated the combined effects of ocean warming and acidification on the temperate coastal marine ecosystems.

Coral reefs are synonymous with the tropical coastal seas. When the ocean temperatures cool in the direction of the poles, corals yield to kelp as the main habitat-forming species. This shift from coral to kelp can be seen evidently on the 2000 km coastline of Japan, where modifications to these ecosystems are ongoing.

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Read More “Ocean warming, acidification shift temperate coastal reefs into simpler ecosystems” »

In a new paper published in Frontiers in Marine Science, scientists call for increased consideration of ocean acidification to help inform future fish stock management in the Arctic Ocean, as well as publishing a roadmap for monitoring commercial fish stocks in this vulnerable and vital region.

The paper, led by scientists from Plymouth Marine Laboratory working with partners from the University of Exeter, Norwegian Institute of Water Research and the East China Normal University, outlines how ocean acidification must be considered with other potential stressors to accurately predict fish stocks in the Arctic, and therefore inform future fish stock management strategies.

The Arctic Ocean is particularly susceptible to ocean acidification and already experiences low pH levels not projected to occur on a global scale until 2100 so a better understanding of the impact of increasing acidity in this region is urgently required.

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In addition, warming amplifies the Arctic’s susceptibility to ocean acidification with continued loss of multi-year ice, increasing the surface area of the ocean available for CO₂ gas exchange and adding to the many pressures already facing the area.

Also highlighted in the study is the remote and often hostile nature of the Arctic Ocean. Collecting in situ data can be costly and challenging. This results in most datasets having a high seasonal bias toward the summer, in addition to little data being collected near multi-year sea ice. Sampling data is often fed into ecosystem models, which are used to project possible changes in stocks and ecosystem function so biased data can lead to inaccurate model outputs.

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Read More “Using remote sensing technologies to understand the impact of ocean acidification on a remote Arctic” »

Human-driven global change is challenging the scientific community to understand how marine species might adapt to predicted environmental conditions in the near-future.

The effects of the uptake of anthropogenic atmospheric CO₂ by oceans affects propagate across the biological hierarchy, from changes in the building blocks of life at nano-scales to organism, physiology and behaviour through ecosystem processes and their properties.

To survive in a reduced pH environment, marine organisms have to adjust their physiology which, at the molecular level, is achieved by modifying the expression of genes. The study of such changes in gene expression can aid in revealing the adaptive mechanisms of life under predicted future ocean acidification conditions (e.g. hypoxia, ocean warming, and ocean acidification).

Making use of natural laboratories
There are a few places on this planet where volcanic activity has CO₂ bubbling from the seafloor creating conditions that are similar to those predicted to occur across the oceans in the near-future. Such natural laboratories can then help us to understand what will happen to marine organisms in the future under an ocean acidification scenario. Therefore, researchers from Research Division for Ecology & Biodiversity of the University of Hong Kong (HKU) and Swire Institute of Marine Science, jointly with researchers from the University of Adelaide, travelled to a remote volcanic island of New Zealand called White Island. They collected samples from CO₂ seeps and nearby locations, and analysed molecular data from a fish species (the Common triplefin) with ecological evidence of being successfully adapted to acidified environments at CO₂ volcanic vents. The findings were published in a peer-reviewed open access journal Evolutionary Applications.

Read More “International joint research reveals how fish adapt to ocean acidification by modifying gene expression” »

Bleaching and cyclone damage to reefs at Lord Howe Island, Australia, observed in March 2019. Credit: Kay Davis

If the trend of declining coral growth continues at the current rate, the world’s coral reefs may cease calcifying around 2054, a new Southern Cross University study has found.

Drawing on research from the late 1960s until now, the paper published in Communications Earth & Environment reveals the global spatiotemporal trends and drivers of coral reef ecosystem growth (known as calcification).

One hundred and sixteen studies from 53 published papers were analyzed.

“It is known that coral reefs have been degrading over time. Our study relies on historical data to quantify the current rate of decline and indicates what could be happening in the future,” said project leader Dr. Kay Davis.

Read More “Declining growth rates of global coral reef ecosystems” »

New research has shown that by injecting an alkalinizing agent into the ocean along the length of the Great Barrier Reef, it would be possible, at the present rate of anthropogenic carbon emissions, to offset ten years’ worth of ocean acidification.

The research, by CSIRO Oceans and Atmosphere, Hobart, used a high-resolution model developed for the Great Barrier Reef region to study the impact of artificial ocean alkalinization on the acidity of the waters in the Great Barrier Reef. The study is based on the use of existing shipping infrastructure to inject a source of alkalinity into the ocean, which could also be considered as an acceleration of the chemical weathering of minerals through natural processes. Their results are published today (June 8, 2021) in the IOP Publishing journal Environmental Research Letters.

Read More “Injecting an alkalinizing agent into the ocean to offset 10 years’ worth of acidification of the Great Barrier Reef” »

Challenging conditions for familiar species like lobsters and scallops loom by mid-century

Familiar organisms like lobsters could be affected by changing ocean conditions in the Northeast in the coming decades (Adobe Stock).

By mid-century, the Northeast is expected to experience significant changes in climate, on land and in the region’s waters. Leaders from across New England and the Canadian Maritime Provinces teamed up with experts to compile a report containing the most complete and up-to-date information on the Gulf of Maine, that is also filled with actionable solutions to increase resiliency in the coming decades – all with hopes of inspiring quick action. Details can be found in he Gulf of Maine 2050 Climate Outlook and Action report.

UConn Assistant Professor in the Department of Marine Sciences Samantha Siedlecki is a co-author on the report, which presents a synthesis of research relevant to the region, including sea level rise, temperature change, and Siedlecki’s focus — ocean acidification. The paper detailing Ocean Acidification projections featured in the report was published on May 12^th in Elementa.

Read More “Gaining a clearer understanding of ocean acidification in the Northeast” »

Some corals can swap out the algae that live inside their tissues for different strains that are more heat tolerant – and these coral species have a better chance of surviving global climate change in the coming decades.

When sea temperatures are too high, corals expel the microscopic algae living in their tissues. This is what occurs during coral bleaching. Losing algae in this way is harmful for the corals because the algae normally provide oxygen for them and remove their waste products. However, marine biologists have previously discovered that when some corals are exposed to warmer temperatures, they can swap the algae inside their tissues for strains that have a higher thermal tolerance.

Cheryl Logan at California State University in Monterey Bay and her colleagues have developed a model to simulate how these corals – and other coral species – will respond to global warming and ocean acidification. They applied their model to 1925 coral reefs around the world under four different climate scenarios.

Read More “Corals swap in heat-resistant algae to better cope with global warming” »

The window of opportunity to save the world’s coral reefs is still open but time is running out. A new study by an international group of scientists, including UvA marine biologists Dr Verena Schoepf and Niklas Kornder, has calculated how coral reef growth is likely to react to ocean acidification and warming under three different climate-change carbon dioxide scenarios: low, medium and worst-case. The study, just published in the journal PNAS, has some good news to offer amid a grim outlook.

‘If the world can reduce carbon dioxide emissions drastically, coral-reef growth will be reduced, but many reefs will still be able to grow,’ says lead author Dr Christopher Cornwall, from the Victoria University of Wellington, New Zealand. ‘Some of them will even keep pace with sea-level rise. Even if we fail with those drastic reductions but do keep within the intermediate emissions scenario, some coral reefs will still keep growing for a short while, but by the end of the century they will all be eroding. If we hit the worst-case scenario, then very shortly all coral reefs will be eroding.’

Impact of climate change

The research by academics in New Zealand, Australia, the United States, France, The Netherlands and the United Kingdom breaks new ground.The interdisciplinary group of scientists formed initially as a working group led by the Australian Research Council’s Centre of Excellence for Coral Reef Studies in 2016. There has been a great deal of individual research investigating the impact of climate change on individual corals and coralline algae, but this work gives broader projections of ocean warming and acidification, and their interaction, on the net carbonate production of coral reefs, which is a measure of coral reef growth.

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Read More “Time running out to save coral reefs” »

Is it possible to simultaneously address the increase of the concentration of carbon dioxide (CO₂) in the atmosphere and the resulting acidification of the oceans? The research of the project DESARC-MARESANUS, a collaboration between the Politecnico di Milano and the CMCC Euro-Mediterranean Center on Climate Change Foundation, explores the feasibility of this process, its chemical and environmental balance, and the benefits for the marine sector, focusing on the Mediterranean basin.

It is now widely recognized that in order to reach the target of limiting global warming to well below 2°C above pre-industrial levels (as the objective of the Paris agreement), cutting the carbon emissions even at an unprecedented pace will not be sufficient, but there is the need for development and implementation of active Carbon Dioxide Removal (CDR) strategies. Among the CDR strategies that currently exist, relatively few studies have assessed the mitigation capacity of ocean-based Negative Emission Technologies (NET) and the feasibility of their implementation on a larger scale to support efficient implementation strategies of CDR. The ocean plays a particular role in the climate system acting as significant sink of atmospheric heat and CO₂; this has caused the additional hazard of ocean acidification, that is the pH reduction of ocean seawater since the pre-industrial period, that is unprecedented in the last 65 million years and has significant implications for marine organisms affecting their metabolic regulation and capability to form calcium carbonate, destabilizing the ecosystem and ultimately threatening vital ecosystem services. Among the ocean-based NETs, artificial ocean alkalinization via the dissolution of Ca(OH)₂, known in short as ocean liming, has attracted attention due to its capability of contemporarily addressing two issues: global warming via increased levels of CO₂ and ocean acidification.

A new study recently published in Frontiers in Climate exploresthe case of ocean alkalinization in detail. The research, realized by the Euro-Mediterranean Center on Climate Change Foundation (CMCC) and the Politecnico di Milano within the Desarc-Maresanus project, with the financial support of Amundi and the collaboration of CO2APPS, presents an analysis of marine alkalinization applied to the Mediterranean Sea taking into consideration the regional characteristics of the basin. Researchers used a set of simulations of alkalinization based on current shipping routes to quantitatively assess the alkalinization efficiency via a coupled physical-biogeochemical high-resolution model (NEMO-BFM) for the Mediterranean Sea (1/16° horizontal resolution that is ~6 km) under an RCP4.5 scenario over the next decades. The alkalinization strategies applied in this study to the Mediterranean Sea illustrate the potential of ocean alkalinization to mitigate climate change by increasing the air-sea flux of CO₂ across the basin and counteracting acidification. In contrast to previous studies, the analyzed scenarios offer a clear pathway into practical implementation being based on realistic levels of lime discharge using the current network of cargo and tanker shipping routes across the Mediterranean Sea.

Two different approaches of alkalinization scenarios have been explored: one with a constant annual discharge of lime over the entire scenario period and another with gradually increasing alkalinization levels proportional to the pH decreases in the baseline scenario RCP4.5. The simulations used in the study suggest the potential of nearly doubling the carbon-dioxide uptake rate of the Mediterranean Sea after 30 years of alkalinization, and of neutralizing the mean surface acidification trend of the baseline scenario without alkalinization over the same time span.

A more recent paper carried out within the project and just published, realizes an estimate of the potential of maritime transport for ocean liming and atmospheric CO₂ removal, highlighting a very high potential discharge of slaked lime in the sea by using the existing global commercial fleet of bulk carrier and container ships. For some closed basins, such as the Mediterranean Sea where traffic density is relatively high, the potential of ocean alkalinization, also with low discharge rates, is far higher than what is needed for counteracting ocean acidification. Therefore, the results of this study highlight from one hand the need for further research for a more precise assessment of the technical aspects of this approach and potential criticalities, from another hand indicates the potential of a regional implementation of ocean liming to the Mediterranean Sea based on the existing network of tankers and cargo ships.

“These two publications provide a key contribution to the international and national scientific and technical communities working to find solutions to these two issues – atmospheric CO₂ removal and counteracting ocean acidification – which we will have to tackle in the future. Even if further investigations are needed, these results are encouraging”, states Stefano Caserini, Professor of Mitigation of Climate Change at Politecnico di Milano and Project leader of the project Desarc-Maresanus.

“In these works the idea of ocean alkalinisation as a mitigation strategy for climate change is for the first time assessed on the base of a technically feasible pathway of implementation providing a first step towards a real-world application. In addition, even if the full ecological consequences of this strategy still require additional research, a solution is indicated that may stabilise the acidity of the seawater counteracting acidification without risking dramatic alterations of the seawater chemistry in the opposite direction, which as of today would have largely unknown consequences.” states the main author of the first article, Momme Butenschön, Lead Scientist of the Research Unit on Earth System Modelling at the CMCC Foundation Euro-Mediterranean Center on Climate Change (CMCC).

Read the full papers published in Frontiers in Climate:

Butenschön M., Lovato T., Masina S., Caserini S., Grosso M. (2021), Alkalinization Scenarios in the Mediterranean Sea for Efficient Removal of Atmospheric CO2 and the Mitigation of Ocean Acidification. Frontiers in Climate – Negative Emission Technologies, volume 3, 11 pages, DOI: 10.3389/fclim.2021.614537

Caserini S., Pagano D., Campo F., Abbá A., De Marco S., Righi D., Renforth P., Grosso M. (2021) Potential of maritime transport for ocean liming and atmospheric CO₂ removal. Frontiers in Climate – Negative Emission Technologies. 3:575900. https://doi.org/10.3389/fclim.2021.575900

Website: www.desarc-maresanus.net

Read More “Reducing ocean acidification by removing CO2: two targets for cutting-edge research” »

The 2020 Prime Minister’s MacDiarmid Emerging Scientist Prize Winner is Dr Christopher Cornwall from Te Herenga Waka Victoria University of Wellington, whose research focuses on the impacts of ocean acidification on marine organisms, including seaweeds and various calcifying algae and corals.

Ocean acidification is the result of changes in seawater pH levels due to increasing levels of atmospheric carbon dioxide. It is one of the biggest threats to the world’s oceans and has the potential to cause the collapse of ecosystems.

Chris’s work investigating ocean acidification, and career in research, has centred largely around three major questions:

1) How is ocean acidification leading to a decline in the growth of organisms with calcium carbonate skeletons?

2) Can reef-building organisms acclimatise or adapt to ocean acidification?

3) How will ocean acidification reduce the growth of coral reefs globally?

Read More “2020 Prime Minister’s MacDiarmid emerging scientist prize winner” »

New challenges to a once tried-and-true method for assessing reef health

Carnegie’s Manoela Romanó de Orte and Ken Caldeira led a research team that deployed a cutting-edge incubator to monitor the metabolic activity of coral and algae in an area of Australia’s Great Barrier Reef that had been damaged by tropical cyclones. The CISME, or Coral In Situ Metabolism and Energetics, instrument is a small chamber that can be placed directly on the coral surface and allow scientists to monitor coral growth by measuring changes in seawater chemistry. Credit: image courstesy of Ken Caldeira.

Washington, DC– Algae colonizing dead coral are upending scientists’ ability to accurately assess the health of a coral reef community, according to new work from a team of marine science experts led by Carnegie’s Manoela Romanó de Orte and Ken Caldeira. Their findings are published in Limnology and Oceanography.

Corals are marine invertebrates that build tiny exoskeletons, which accumulate to form giant coral reefs. Widely appreciated for their beauty, these reefs are havens for biodiversity and crucial for the economies of many coastal communities. But they are endangered by ocean warming, seawater acidification, extreme storms, pollution, and overfishing.

Read More “Algae growing on dead coral could paint a falsely rosy portrait of reef health” »

Shelled organisms helped buffer ocean acidification by consuming less alkalinity from seawater.

Microscopic fossilized shells are helping geologists reconstruct Earth’s climate during the Paleocene-Eocene Thermal Maximum (PETM), a period of abrupt global warming and ocean acidification that occurred 56 million years ago. Clues from these ancient shells can help scientists better predict future warming and ocean acidification driven by human-caused carbon dioxide emissions.

Led by Northwestern University, the researchers analyzed shells from foraminifera, an ocean-dwelling unicellular organism with an external shell made of calcium carbonate. After analyzing the calcium isotope composition of the fossils, the researchers concluded that massive volcanic activity injected large amounts of carbon dioxide into the Earth system, causing global warming and ocean acidification.

They also found that global warming and ocean acidification did not just passively affect foraminifera. The organisms also actively responded by reducing calcification rates when building their shells. As calcification slowed, the foraminifera consumed less alkalinity from seawater, which helped buffer increasing ocean acidity.

Read More “Oceans were stressed preceding abrupt, prehistoric global warming” »

The oceans are becoming more acidic because of the rapid release of carbon dioxide (CO₂) caused by anthropogenic (human) activities, such as burning of fossil fuels. So far, the oceans have taken up around 30% of all anthropogenic CO₂ released to the atmosphere. The continuous increase of CO₂ has a substantial effect on ocean chemistry because CO₂ reacts with water and carbonate molecules. This process, called ‘ocean acidification,’ lowers pH, and calcium carbonate becomes less available. This is a problem for calcifying organisms, such as corals and molluscs, that use calcium carbonate as the main building blocks of their exoskeleton.

In particular, organisms that build their shells from a type of calcium carbonate known as ‘aragonite’ are in trouble because aragonite is extremely soluble in sea water. Sea butterflies, tiny, swimming sea snails, build their shells of aragonite. Therefore, they are also known as ‘the canaries of the coalmine’ because they are expected to be amongst the first organisms to be affected by ocean acidification.

Read More “Sea butterflies already struggle in acidifying Southern Ocean” »

Team will assess vulnerability of aquaculture and restoration efforts in Chesapeake Bay

The excess carbon dioxide responsible for global warming also increases the acidity of seawater, challenging the growth and survival of oysters and other shellfish. A team led by researchers at William & Mary’s Virginia Institute of Marine Science is now helping oyster growers and restoration specialists better manage their future responses to acidification in the Chesapeake Bay.

The team, funded by the NOAA Ocean Acidification Program, is led by VIMS researchers Marjy Friedrichs and Emily Rivest, along with David Wrathall of Oregon State University. Other team members include Mark Brush, Pierre St-Laurent, and Karen Hudson of VIMS, Aaron Bever of Anchor QEA, and Bruce Vogt of NOAA’s Chesapeake Bay Office. The team calls their project STAR, for Shellfish Thresholds and Aquaculture Resilience.

“Coastal acidification and its associated co-stressors present a serious and credible threat to the success of both oyster aquaculture and oyster restoration in the Bay,” says Friedrichs. The co-stressors include nutrient pollution, warmer Bay waters, and pulses of freshwater from rainstorms made more intense by global atmospheric changes. Previous research has shown these factors can intensify the negative impacts caused by ocean acidification alone.

Read More “NOAA funds VIMS to study impact of ocean acidification on oysters” »

Rising ocean temperatures and ocean acidification could have negative cumulative effects that slow the growth of tropical coral reefs, according to a UCLA-led study published in early January.

The study examined the growth of two types of tropical corals – commonly known as cauliflower coral and hood coral – at different water temperatures and acidities. At a lower temperature, the corals were able to compensate for the acidification and continue building their skeletons. But at a higher temperature, the corals grew much slower.

In order for coral reefs to survive despite constant degradation by waves and human activity, individual reef-building corals must be able to efficiently build their skeletons through a process called calcification, said Maxence Guillermic, a UCLA postdoctoral researcher and lead author of the study. The coral must maintain the correct internal carbonate conditions to allow the skeletal building material, calcium carbonate, to precipitate, he added.

Read More “UCLA-led study highlights effects of ocean acidification, warming on coral reefs” »

Researchers from the University of Tsukuba find that in the presence of ocean acidification, feedback loops keep degraded turf algal states stabilized, inhibiting the recruitment of coral and other algae.

Tsukuba, Japan—It’s tough out there in the sea, as the widespread loss of complex marine communities is testament to. Researchers from Japan have discovered that ocean acidification favors degraded turf algal systems over corals and other algae, thanks to the help of feedback loops.

In a study published this month in Communications Biology, researchers from the University of Tsukuba have revealed that ocean acidification and feedback loops stabilize degraded turf algal systems, limiting the recruitment of coral and other algae.

Read More “Turf wars: ocean acidification and feedback loops lock in turf algal systems” »

A NCCOS and NOAA Ocean Acidification Program sponsored study investigated how physical properties such as winds, tides, and currents impact estuarine acidification and carbonate chemistry in the Chesapeake Bay estuary, a complex and little studied undertaking. A coupled hydrodynamic-carbonate chemistry model was used to understand the wind-driven variability in the estuarine carbonate system. Large temporal pH fluctuations and low pH events were documented that could negatively impact acidification-sensitive species such as oysters.

A major challenge in the study of estuarine acidification is the strong temporal and spatial variability of carbonate chemistry resulting from a wide array of physical forces such as winds, tides and river flows. Most studies of estuarine carbonate system dynamics have been limited to the along-channel direction, while lateral pH dynamics (e.g., channel to shore) has received less attention.

Read More “Climate-induced wind upwelling could further acidify Chesapeake Bay” »

Addressing the growing problem of ocean acidification in New England waters before it severely damages the region’s crucial shellfish industry is the focus of an important report by a commission of Massachusetts legislators, state environmental agencies, marine research and conservation organizations, and shellfish industry leaders. Woods Hole Oceanographic Institution (WHOI) is a part of the 18-member Massachusetts Special Legislative Commission on Ocean Acidification and helped co-author the 84-page report released today.

Read More “WHOI working to address increasing ocean acidification; protect region’s vital shellfish industry” »

Under increasing global warming, tropical fish are escaping warmer seas by extending their habitat ranges towards more temperate waters.

But a new study from the University of Adelaide, published in Nature Climate Change, shows that the ocean acidification predicted under continuing high CO₂ emissions may make cooler, temperate waters less welcoming.

“Every summer hundreds of tropical fish species extend their range to cooler and temperate regions as the waters of their natural habitat become a little too warm for comfort,” says lead author Ericka Coni, Ph.D. student in the University’s School of Biological Sciences. “For at least two decades, Australian temperate reefs have been receiving new guests from the tropics.

Read More “High carbon dioxide to slow tropical fish move to cooler waters” »