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How to make an acid-proof oyster

Oyster farms face a fading future in acidifying oceans. But a Vancouver Island research program is trying to breed oysters that can resist the change

Gulls squawk as the normally quiet Deep Bay Marina bustles with the arrival of fishing boats assembling for an imminent commercial herring opening near Denman Island. A two-minute boat ride away from the harbour, Vancouver Island University (VIU) scientist Tim Green balances across a dock the size of a squash court decked with wet plywood slick as grease. He kneels down to haul a small black net full of juvenile Pacific oysters from the water, each one carefully numbered with a small tag. 

But the problems are even more fundamental than that: ocean acidification, sometimes considered climate change’s little-known cousin, presents a threat to the oysters’ ability to survive even past infancy.

Green is an internationally recognized expert on shellfish immunology. Several years ago, when VIU was looking for someone to head up an oyster genomics and breeding program, he jumped at the opportunity to help address an existential threat facing British Columbia’s shellfish sector worth $30 million annually in farmgate sales. Green is betting on the belief that the key to future-proofing oysters against the impacts of climate change is through breeding and selecting for oysters with traits that make them more resilient to rising ocean acidity and water temperatures.

A mollusk in the coalmine

A single axle delivery truck, loaded with fresh clams and oysters destined for Vancouver, pulls out of Fanny Bay Oysters and onto the Old Island Highway, before heading south. The midden of oyster shells piled deep outside the weathered and whitewashed Fanny Bay Oysters headquarters on the shores of Baynes Sound is a testament to longevity and more than three decades in the BC shellfish industry. 

Oysters, once settled, don’t move much. If the water gets too acidic, too warm, too nutrient-poor, or if a sudden deluge of mud smothers them, there’s not much the shellfish can do about it. The industry is much the same: unlike other fisheries, oyster growers are rooted in place. They’re accustomed to a degree of uncertainty, and when you can do little to control the growing environment, oyster mortality is an accepted cost of doing business. However, three years ago when Fanny Bay Oysters started experiencing unprecedented mortality rates, general manager Brian Yip knew something wasn’t right in the ocean.

“It’s the million-dollar question what the exact cause of increased mortality is, but it seems to be linked to water temperature and acidification,” Yip says as he looks out his office window at Baynes Sound, its busy surface like a checkerboard of oyster growing rafts.

Though many questions remain unanswered about the Pacific oyster’s ability to survive in a changing ocean environment, the link between ocean acidification and oyster health is now well understood. BC oyster growers acquire most of their seed, basically baby oysters, primarily from Chile, but also from hatcheries in the American Pacific Northwest like the Whiskey Creek Shellfish Hatchery. In the late 2000s, workers at the Whiskey Creek facility, located just south of Tillamook Bay on the Oregon coast, were faced with a sudden and big problem—hundreds of thousands of dead oyster seed. At first, low oxygen and pathogenic bacteria were considered the most likely culprits, but when these potential causes were eliminated, attention shifted to changes in the pH levels of seawater. 

A decade earlier, the scientific community had begun ringing the alarm bell about ocean acidification, but at that time there was still much to learn about the impact on marine life. 

Prompted by this wave of unexplained hatchery die-offs, Oregon State University marine ecologist George Waldbusser focused his attention on acidification. In a 2012 peer-reviewed study, Waldbusser showed definitively how acidic water impacts the ability of larval oysters to build hard calcium carbonate shells at a critical time in their life cycle—the first 48 hours. Within the span of just two days, young oysters need to build their shells and begin feeding at a rate fast enough to survive. In the presence of acidic—or corrosive—seawater, the larvae expend too much energy creating their portable homes, leaving not enough left over for these tiny mollusks to swim and feed. In the American Pacific Northwest alone, ocean acidification was costing the oyster industry an estimated US$110 million. 

Waldbusser’s scientific sleuthing also spotlighted fascinating but also troubling changes in broad earth-scale systems. Historically, pH levels in the oceans have been kept relatively stable through natural processes; the rate at which the seas were able to absorb acidifying, or pH lowering, carbon dioxide from the atmosphere was balanced by alkaline, continental erosion, and run-off. However, as anthropogenic greenhouse gas emissions soar, ocean chemistry is being thrown off balance; carbon dioxide is now increasing at a rate that scientists estimate is between 100 and 1,000 times faster than the weathering processes that produce alkalinity can keep up with. That’s why the story of the young oyster is yet another case of a canary in the coalmine of climate change.

Once scientists proved that acidity in hatchery seawater was the smoking gun, the problem had a relatively easy fix: buffering the water to raise the pH and lower acidity. But a hatchery is a closed system that enables humans to tinker with water chemistry in a way that’s not possible in the open ocean. It might take tinkering with something even more fundamental than the water they breathe.

A genetic fix

Back on Baynes Sound, Tim Green and a research assistant measure the shells of the juvenile oysters then jot assiduous notes in a logbook. Afterwards, he returns the bivalves to the net bag, sews it shut, and lowers it into the water. Air bubbles drift and pop to the surface then this bag of tiny oyster disappears into the depths of the sound. According to Green, the scientific literature is so far mixed on whether acidification negatively affects oysters after leaving the security of the hatchery. In fact, there’s some speculation that artificially buffering the hatchery seawater in which young oysters are reared may even do harm, making them less able to withstand acidification in the wild and open ocean where they will grow to maturity in just two to three years. 

“This is definitely an area that requires further research,” Green says.

And in the absence of scientific certainty, breeding a tougher, more resilient oyster, able to withstand warmer and more acidic seas, may be the only hope for shellfish cultivation that as a commercial enterprise got its start on BC’s coast in the mid 1800s, but for First Nations is a practice with a long history going back thousands of years. 

There is reason for optimism. In Green’s native Australia, the shellfish industry has a good track record breeding Pacifc oysters, which at first focused on growth rate and shell shape. In 2010, with the arrival of oyster herpesvirus in Australian waters, the industry shifted focus and was able to successfully breed oysters resistant to this virulent disease that was killing between 60 to 100% of juvenile oysters. But breeding oysters for resilience to warming and increasingly acidic oceans is new territory.  

Jim Russell, executive director of the BC Shellfish Growers Association, spends a lot of time thinking about the perilous future of the Pacific oyster, which accounts for more than 60% of BC’s shellfish sales. 

If it was simply a matter of migrating the oyster growing industry further up the BC coast where the climate is cooler and the ocean may be less susceptible to mid-summer temperature spikes, then Fanny Bay Oysters, Mac’s Oysters, Nova Harvest, and the dozens of other smaller commercial shellfish growers would pull up stakes and head north. But it’s not that easy. 

Aside from its nutrient rich waters, Baynes Sound is valuable for its proximity to a highway, an important piece of infrastructure for a product like oysters, which, when fresh, are expensive to get to market. And even if it were possible to move the industry to colder waters, that still wouldn’t mitigate the threat of ocean acidification. 

Once a grower seeds a beach with young oysters or suspends them in trays below rafts, nature looks after the rest, as long as humans look after the marine ecosystem. But the very thing that makes oysters so enviably self sustaining is also what makes them acutely vulnerable in a world where the impacts of human-caused climate change are being tallied on the balance sheets of businesses like Fanny Bay Oysters.  

“We’re environment takers, not environment makers. So yes, we believe genomics should be the focus because we can’t control these other environmental factors,” Russell says. “Sixty per cent of our industry is Pacific oysters. If we lose that, we’ll be scrambling.”

Andrew Findlay, Capital Daily, 17 March 2021. Full article.

Opinion: California legislators need to take action to address climate crisis

Ocean acidification is only getting worse and with it, so is the quality of life for many organisms off the California coast. The state needs to take swift action to reverse this worrying trend. (Kanishka Mehra/Photo editor).

The climate crisis is as urgent of an issue as ever, and California’s lack of action isn’t helping.

Over the past century, ocean surface temperatures have risen by an average of 0.13 degrees Celsius each decade. This rise in temperature is a result of increased levels of greenhouse gases in the atmosphere dating back to the 1970s,and 93% of this excess heat has been absorbed by the ocean, according to the Intergovernmental Panel on Climate Change.

On top of this, ocean acidification, a process that occurs when atmospheric carbon dioxide dissolves into water, is also affecting oceans at an increasingly alarming rate.

Continue reading ‘Opinion: California legislators need to take action to address climate crisis’

Could seaweed be a salve to debate over salmon farming?

Seaweed is great at dealing with the waste from salmon farms and providing producers with another cash crop, says researcher Thierry Chopin. Photo by Steve Backman.

For well over a decade, scientists on Canada’s coasts have demonstrated how growing seaweed or shellfish alongside salmon farms can provide a host of benefits — economic and ecological.

Researcher Thierry Chopin has been pitching the idea of co-cultivating multiple species together, or Integrated Multi-Trophic Aquaculture (IMTA), since the late 1990s.

The notion behind co-cultivation, or IMTA, is that extractive species like seaweed, mussels, or sea cucumbers can filter or flourish from the uneaten feed, waste, and byproducts from fish farms.

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Lobster research explores ocean warming effects

ORONO — A team of researchers from the University of Maine’s Darling Marine Center in Walpole and Bigelow Laboratory for Ocean Sciences in East Boothbay and the Maine Department of Marine Resources in West Boothbay Harbor recently published their research on the effects of ocean warming and acidification on gene expression in the earliest life stages of the American lobster.

The work was published in the scientific journal Ecology and Evolution with collaborators from the University of Prince Edward Island and Dalhousie University in Canada.

The team’s experiments examined the gene regulatory response of post-larval lobsters to the separate and combined effects of warming and acidification anticipated by the end of the 21st century. They found that genes regulating a range of physiological functions, from those controlling shell formation to the immune response, are either up- or down-regulated. Importantly, they observed that the two stressors combined induced a greater gene regulatory response than either stressor alone.

The results from the study indicate that changes in gene expression of post-larval lobster may act as a mechanism to accommodate rapid changes in the ocean environment. Team leader Maura Niemisto noted that “there is still need for further study to determine how rapidly populations of the species may be able to adapt to changing conditions. To better understand how gene regulation in response to environmental changes functions within the species, we should look at subpopulations and multigenerational studies to determine the extent of species’ capacity to respond to altered environmental conditions.”

Continue reading ‘Lobster research explores ocean warming effects’

Ocean acidification commission creates council

BOSTON – The Ocean Acidification Commission recently hosted its final public hearing to discuss falling pH levels and rising temperatures in the state’s surrounding waters, and the risk it presents to the states shell fishing industries.

The changing pH levels are particularly dangerous for shell fishing industry. When pH levels drop shellfish, such as oysters, and lobsters are unable to form strong shells.

As a result, fewer organisms make it past the larvae stage and those who do make it to adulthood are much more susceptible to predation.

Continue reading ‘Ocean acidification commission creates council’

One-two punch against corals: how stress factors interact

A new study in the prestigious journal Science Advances shows that stress from rising water temperatures reduces ability of corals to adapt to ocean acidification.

About a quarter of the carbon emissions driving global warming are absorbed by the oceans, leading to lower pH values in the water and making it more acidic. Global warming is also causing water temperature in the oceans to rise, which leads to the bleaching of coral reefs worldwide. Now, a new study reveals that increased CO2 levels in the water and ocean warming can interact to threaten reef-building corals.

The international team of authors, led by the University of California, included Professor Hildegard Westphal and Dr. Claire Reymond from the Leibniz Centre for Tropical Marine Research (ZMT), as well as Professor Justin Ries, a former fellow of the Hanse-Wissenschaftskolleg and visiting scientist at the ZMT. Furthermore, researchers from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) in Bremerhaven and the Max Planck Institute for Marine Microbiology in Bremen were involved in the study.

Continue reading ‘One-two punch against corals: how stress factors interact’

Interrelation of quality parameters of surface waters in five tidewater glacier coves of King George Island, Antarctica


  • Repeated investigation in unprecedented proximity of 5 glacial fronts in Antarctica
  • Analysis of physical, chemical and biological water quality parameter interrelations
  • Correlations found between glacial meltwater and physicochemical parameter shifts
  • pH values shown rising with glacial meltwater presence
  • Varied biological parameter trends dependent on the distance from the glacial front


For further understanding of glacial meltwater’s (GMW) impacts on marine environments, five coves adjacent to diverse glaciers of King George Island, Antarctica were investigated through surface measurements of water quality parameters. Measurements were conducted 49 times during January, February and March of 2019, with sampling performed in unprecedently close proximity to glacial fronts (< 50 m distance from glacier termini in each cove) to create a unique dataset. Four out of five of the coves were inspected through vertical profiling to show water-column stratification. The findings showed synchronized GMW influence causing decreases of salinity, temperature, and dissolved organic matter contents, combined with increased pH, turbidity, and dissolved oxygen values. GMW presence was most correlated with dissolved organic matter content (93% of the cases >0.5 correlation noted with either turbidity or salinity) and least correlated with water temperature (from 22% to 77% of the cases with >0.5 correlation, dependent on the cove). In contrast to previous studies, the pH values of seawater infused with GMW were higher than those of the surrounding water. GMW was shown to stay in the boundary surface layer of the water column. Phytoplankton pigment quantities depending on the localization, time and distance from the glacial termini presented varied response to GMW (positive, negative or ambivalent with hotspots of simultaneous high GMW and phytoplankton quantities). The positive response to glacial water input was more often noted in measurements of phycoerythrin (from 0 to 80% of the cases depending on the cove) rather than chlorophyll A (from 0 to 25%) and maximum quantities of both biological pigments were found at a depth of approximately 5-10 m.

Continue reading ‘Interrelation of quality parameters of surface waters in five tidewater glacier coves of King George Island, Antarctica’

Assimilating synthetic Biogeochemical-Argo and ocean colour observations into a global ocean model to inform observing system design

A set of observing system simulation experiments was performed. This assessed the impact on global ocean biogeochemical reanalyses of assimilating chlorophyll from remotely sensed ocean colour and in situ observations of chlorophyll, nitrate, oxygen, and pH from a proposed array of Biogeochemical-Argo (BGC-Argo) floats. Two potential BGC-Argo array distributions were tested: one for which biogeochemical sensors are placed on all current Argo floats and one for which biogeochemical sensors are placed on a quarter of current Argo floats. Assimilating BGC-Argo data greatly improved model results throughout the water column. This included surface partial pressure of carbon dioxide (pCO2), which is an important output of reanalyses. In terms of surface chlorophyll, assimilating ocean colour effectively constrained the model, with BGC-Argo providing no added benefit at the global scale. The vertical distribution of chlorophyll was improved by assimilating BGC-Argo data. Both BGC-Argo array distributions gave benefits, with greater improvements seen with more observations. From the point of view of ocean reanalysis, it is recommended to proceed with development of BGC-Argo as a priority. The proposed array of 1000 floats will lead to clear improvements in reanalyses, with a larger array likely to bring further benefits. The ocean colour satellite observing system should also be maintained, as ocean colour and BGC-Argo will provide complementary benefits.

Continue reading ‘Assimilating synthetic Biogeochemical-Argo and ocean colour observations into a global ocean model to inform observing system design’

Some fish develop larger sex organs when CO2 levels are high

A new study from the University of Adelaide has revealed that some fish develop larger sex organs when they are exposed to high levels of CO2.

A new study from the University of Adelaide has revealed that some fish develop larger sex organs when they are exposed to high levels of CO2. The experts report that the reproductive capacity of these fish will increase as the oceans continue to absorb carbon emissions.

The researchers said that far from the negative effects expected under the elevated CO2 levels in our oceans predicted for the end of the century, these fish capitalize on changes to the underwater ecosystems to produce more sperm and eggs.

“The warming oceans absorb about one-third of the additional CO2 being released into the atmosphere from carbon emissions, causing the oceans to acidify,” said study lead author Professor Ivan Nagelkerken.

Continue reading ‘Some fish develop larger sex organs when CO2 levels are high’

Ocean acidification affecting California mussels (text and audio)

Buoys in the water at the Carlsbad Aquafarm where owners grow oysters and mus...
Above: Buoys in the water at the Carlsbad Aquafarm where owners grow oysters and mussels on Aug. 26, 2019.

A UC San Diego researcher says an increasingly acidic ocean is having an impact on shellfish that live in the nearshore environment.

Graduate student Elizabeth Bullard studied recent mussel samples and compared them to records of mussels captured along the California coast 60 years ago.

Bullard expected to find that the animal’s shells were harder and contained more of the carbonate mineral aragonite as the shellfish adjusted to a warming ocean.

Continue reading ‘Ocean acidification affecting California mussels (text and audio)’

New edition of the “OA-ICC Highlights”, July-December 2020

The new edition of the “OA-ICC Highlights”, our newsletter, summarizes the project’s main activities and achievements over the period July-December 2020. This newsletter highlights a virtual OA conference, organized with GOA-ON, new funding and staff, and planning for 2021. Previous editions can be viewed here.

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Volcanic eruptions directly triggered ocean acidification during Early Cretaceous

Around 120 million years ago, the earth experienced an extreme environmental disruption that choked oxygen from its oceans.

Known as oceanic anoxic event (OAE) 1a, the oxygen-deprived water led to a minor — but significant — mass extinction that affected the entire globe. During this age in the Early Cretaceous Period, an entire family of sea-dwelling nannoplankton virtually disappeared.

By measuring calcium and strontium isotope abundances in nannoplankton fossils, Northwestern earth scientists have concluded the eruption of the Ontong Java Plateau large igneous province (LIP) directly triggered OAE1a. Roughly the size of Alaska, the Ontong Java LIP erupted for seven million years, making it one of the largest known LIP events ever. During this time, it spewed tons of carbon dioxide (CO2) into the atmosphere, pushing Earth into a greenhouse period that acidified seawater and suffocated the oceans.

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Ocean acidification may make some species glow brighter

These glowing specks are sea fireflies (Vargula hilgendorfii) on a beach in Japan. A new analysis suggests that they might glow a bit brighter as the ocean becomes more acidic.

A more acidic ocean could give some species a glow-up.

As the pH of the ocean decreases as a result of climate change, some bioluminescent organisms might get brighter, while others see their lights dim, scientists report January 2 at the virtual annual meeting of the Society for Integrative and Comparative Biology.

Bioluminescence is de rigueur in parts of the ocean (SN: 5/19/20). The ability to light the dark has evolved more than 90 times in different species. As a result, the chemical structures that create bioluminescence vary wildly — from single chains of atoms to massive ringed complexes.

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Ocean acidification commission

Event Details

Status: Upcoming

Event Date: Thursday, January 14, 2021

Start Time: 11:00 AM

Location: Virtual Hearing

Event Description

Ocean Acidification Commission

Discuss OA report release

Meeting ID: 857 6277 4455

Passcode: 258991

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Ocean acidification- a new threat to marine ecosystem discussed in Monrovia

Human-made carbon dioxide (CO2) emissions have taken residence in the ocean at significant proportion and causing unprecedented changes to ocean chemistry by reducing the water’s pH level, leading to a collection of chemical changes dubbed ocean acidification.

Some of the participants pose for group photos

With continuous CO2 emissions, scientists predict that the menace will intensify to the detriment of marine ecosystems and the services they provide to society, particularly coastal communities. This is a risk, scientists from across Europe, Africa and the United States are working to avert by holding a side event in Monrovia virtually and in-person on the weekend of January 8, 2021, to promote awareness and remedy research gaps in Africa- a continent proven to lack technical resources that would enable it to face this fastest-growing threat.

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Corals bleached from heat become less resilient to ocean acidification

Cat’s Paw Coral (Stylophora pistillata)

Corals get a double-whammy negative from heat – those that are bleached as a result of heat stress also become less resilient to ocean acidification.

Robert Eagle at the University of California, Los Angeles and his colleagues have analysed the effect of elevated temperatures on the growth of two species of stony coral when the corals are also exposed to ocean acidification.

The acidification of oceans occurs as result of carbon dioxide in the atmosphere being absorbed by seawater. The results are a decrease in the pH of the water, a decrease in its concentration of carbonate ions and a drop in the saturation states of calcium carbonate minerals.

Continue reading ‘Corals bleached from heat become less resilient to ocean acidification’

Raising ocean acidification awareness and research gaps in Africa: scientists meet to brainstorm

Many African countries rely heavily on their coasts and rivers for economic growth and well-being. Unfortunately, Africa’s marine and coastal ecosystems face severe environmental threats, such as untreated wastewater discharge, illegal fishing, and habitat degradation, all combined with human-induced climate change. The rapidly increasing atmospheric carbon dioxide (CO2) alters the climate and the chemistry of the ocean. Hence the ocean has absorbed one-fourth of anthropogenic CO2, thereby causing an increase in seawater acidity, a process referred to as ocean acidification.

The overwhelming evidence demonstrates that ocean acidification has the potential to negatively marine ecosystems and their associated services. While a global reduction of CO2 emissions (mitigation) is the ultimate solution, local adaptation strategies are needed to minimize ocean acidification’s negative effects. Currently, the lack of data on ocean acidification and its impacts for Africa is strongly limiting the potential to develop and implement such strategies. Ocean Acidification Africa (OA-Africa; is a pan-African network working to coordinate and promote ocean acidification awareness and research in Africa.  The network is composed of more than 100 scientists interested in conducting ocean acidification research in Africa. OA- Africa is part of the wider Global Ocean Acidification Observing Network  (  as one of seven regional hubs.

Continue reading ‘Raising ocean acidification awareness and research gaps in Africa: scientists meet to brainstorm’

Long-term emissions cuts are needed to slow ocean acidification

During the first half of 2020, global greenhouse gas emissions dropped by about nine percent in the midst of the COVID-19 outbreak. People around the world reported seeing signs that “nature was healing” as a result of a steep decline in human activities such as transportation and production. 

However, a new study from UC Boulder has shown that the positive changes seen in natural ecosystems were not reflected throughout Earth’s oceans. 

Professor Nicole Lovenduski reports that there were no significant reductions in ocean acidification as a result of lower emissions. Even if emissions had been reduced at four times the rate in the first half of last year, changes in the ocean would have been barely noticeable, according to the study.

Continue reading ‘Long-term emissions cuts are needed to slow ocean acidification’

Hearing: ocean acidification commission

Event Details

Status: Rescheduled

Event Date: Original Start Date: Tuesday, December 8, 2020  Friday, January 8, 2021

Start Time: 3:00 PM

Location: Virtual Hearing

Event Description: Ocean Acidification Public Hearing and Commission Meeting

Title: Ocean Acidification Public Hearing and Commission Meeting


3pm-4pm: Public hearing on the draft Ocean Acidification report

4pm-5pm: Vote on the final commission report

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