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Octopuses May Be Adapting to The Rising Acidity of Our Oceans, Study Suggests

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We know that all the excess CO2 we’re pumping into the air – alongside a host of other damaging effects – is driving up the acidity of the oceans as it sinks and dissolves into the water, but it seems as though the hardy octopus can find ways to adapt to its rapidly changing environment.


Previous research into the impact of ocean acidification on cephalopods such as octopuses, cuttlefish, and squid has shown some indication increased carbon dioxide in the water could negatively impact this type of marine life.

However, in a new study, a group of Octopus rubescens – a species of octopus common to the west coast of North America – were observed adjusting their routine metabolic rate (RMR) over a series of weeks in response to lowering pH levels in the surrounding water.

“Challenges to an organism’s physiology are often reflected in changes in energy use and therefore can be observed as changes in aerobic metabolic rate,” write the researchers in their paper.

A total of 10 octopuses were studied under controlled lab conditions, with RMR measured immediately after exposure to acidic water, after one week, and after five weeks. Critical oxygen pressure – a measure of whether not not animals are getting enough oxygen – was monitored at the same time.

To begin with, high levels of metabolic change were detected in the creatures – a sort of shock reaction that actually conflicts with earlier research into cephalopods, which had recorded a reduction in metabolic change in similar scenarios.


However, RMR had returned to normal after one week, and remained the same five weeks later, suggesting some adaptation had occurred. The increased acidity did have an impact on the ability of the octopuses to function at low oxygen levels, however.

“This response in RMR suggests that O. rubescens is able to acclimate to elevated CO2 over time,” write the researchers. “The observed increase in RMR may be the result of multiple acute responses to hypercapnia [increased CO2 in the blood], possibly including both behavioural and physiological strategies.”

Those strategies could include preparing to move to find a new stretch of water to inhabit, for example, the researchers suggest (something that wasn’t possible here). The short RMR boost might also reflect the octopuses making quick adjustments to their biological processes to suit the new acid level.

The study is the first to look at both short-term (one week) and longer-term (five week) changes in metabolism rates in cephalopods in response to ocean acidification. We know these creatures are tough, and it seems they even have coping strategies that might allow them to adapt to humans destroying the natural environment all around them.

None of this means that we should be okay with the current climate crisis though, or not be trying to make major changes to reverse it. When we don’t take proper care of the planet, it’s not just ourselves that we’re potentially dooming to extinction.

Also, these tests were done in controlled laboratory conditions that don’t take into account many other interlinking factors in the animals’ natural environment. For instance, even if the octopus themselves are able to adjust, what about their food supply?

“While this species may be able to acclimate to near-term ocean acidification, compounding environmental effects of acidification and hypoxia may present a physiological challenge for this species,” write the researchers.

The research has been published in Physiological and Biochemical Zoology.


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These 20 Companies Caused More Than One-Fifth of Ocean Acidification Since 1965

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Our oceans are acidifying at a rate not seen in 66 million years. They’re now 26 percent more acidic since 1880, which is profoundly changing ecosystems and impacting the fisheries that rely on them, all around the world.


This is not only threatening countless jobs, including 4.3 million livelihoods relying on reefs in The Coral Triangle, and 43,000 jobs along the west coast of the US, but our food security, too.

new study shows exactly who is to blame. Just twenty companies caused over one fifth of the ocean acidification that occurred since 1965. This is the time period after these companies understood the dire impacts of their industry; they include Exxon, Chevron, BP, Shell and Saudi Aramco.

In fact, climate scientist Rachel Licker from the Union of Concerned Scientists (UCS) and colleagues have shown that the largest 88 gas, oil and coal producers and cement manufacturers are responsible for more than half of the ocean acidification since 1880.

“We’ve known for several decades that burning fossil fuels is by far the largest driver of ocean acidification, but we weren’t able to track how much any one fossil fuel company contributed to the problem, and in what way,” said Licker.

“Scientists can now quantify how much more acidic the ocean has become as a result of each fossil fuel company’s products.”


Ocean acidification occurs when excess CO2 dissolves into seawater, producing a series of chemical reactions that lead to more hydrogen ions, increasing the water’s acidity. This altered ocean chemistry has already led to a 10 percent decrease in carbonate concentrations since industrialisation.

Less carbonate means it’s harder for calcium carbonate to form; this is a vital molecule for most marine animals because it is part of their shells and exoskeletons. And if the concentration of carbonate drops too low, calcium carbonate dissolves.

“The organisms at risk from acidification form the foundation of the marine ecosystem food chain – including some types of plankton, algae, shellfish, and coral that may struggle to grow and survive in a future warmer, more acidic ocean,” warns biogeochemist Scott Doney from the University of Virginia.

Increased acidification has been shown to reduce the survival of baby krill and other shellfish, and change fish behaviour in ways that make them more vulnerable to predation.

Ocean acidification is happening independently of, but in combination with, climate change – with the effects of each often compounding the other. As climate-change-exacerbated heatwaves cause coral bleaching, the ability of corals to recover is hampered by increased acidity, slowing their calcium carbonate reliant growth and reducing their reproduction.


Building on methods that linked temperature and sea level rise with responsible companies in 2017, Licker and colleagues calculated the amount of ocean acidification caused by fossil fuels during extraction, refinement and use across two time periods. Because CO2 builds up in the atmosphere over time, they examined the effects of cumulative emissions since industries began emitting in 1880, all the way to 2015.

“We also examined acidification due to emissions from 1965 to 2015, roughly consistent with the period when major fossil fuel companies were increasingly aware that continued emissions from the use of their products posed significant climate risks,” Doney told ScienceAlert.

The researchers also identified some regions that are disproportionately more affected by increasing acidity, including the Coral Triangle, Peru Current, and California Current. These areas have already experienced large declines in surface water pH and are particularly vulnerable in terms of ecology and human dependence.

Only one day after this report was released, Saudi Aramco, who tops the ocean acidification contribution chart, became the most valuable listed company in history. Despite having vast amounts of resources, none of these major carbon polluters are showing any sign of changing their ways.

They still plan massive increases in fossil fuel production, while funnelling multi-millions of dollars into obscuring the science and prevent action against them, with the aid of political leaders who have failed to implement policies to reign them in, even as their citizens suffer the consequences.


“Companies could have acted responsibly to inform the public about risks and taken actions to reduce emissions. They chose instead to disinform and delay,” said UCS science policy researcher Peter Frumhoff.

“By putting a number on fossil fuel company contributions to disruptive ocean acidification, our study can inform decisions about their responsibilities for damages that could have – and should have – been avoided.”

This new study may help bolster litigation cases against the fossil fuel industry, such as those mounting in the US, including Pacific Coast Federation of Fishermen’s Association who have filed a lawsuit against 30 fossil fuel companies.

“Our study provides a scientific basis for working on research, marine resource management, policy, and legal aspects of ocean acidification moving forward,” said Doney.

He believes we must now not only look to limiting future human carbon emissions, but also find ways to adapt to the lower pH our waters are already experiencing.

As for what we all can do, divesting as much as we can from fossil fuel companies, voting for leaders who have no links to these companies and speaking out about what we’re facing are all important tasks.

“The extent and severity of future harms of ocean acidification and climate change on marine species and ecosystems, and the human communities dependent upon them, will be largely determined by the future course of further carbon emissions,” the researchers conclude.

You can read the full peer-reviewed report at Environmental Research Letters.


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That Dinosaur-Killing Asteroid Instantly Acidified Our World’s Oceans, Too

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We know that the Chicxulub impactor was responsible for the extinction of the land-based dinosaurs when it slammed into Earth some 66 million years ago. But new research shows the asteroid severely acidified the oceans too, wiping out much of the life residing underwater.


It’s the first direct evidence scientists have found that the dino-destroying impact was also to blame for the instant acidification of the waters – enough to prompt a mass extinction that should act as a warning for us today.

Significant amounts of marine life were wiped out by the Chicxulub asteroid, the researchers say; it seems there wasn’t a gradual build-up of acid levels caused by volcanic activity, as had been previously hypothesised.

“Our data speaks against a gradual deterioration in environmental conditions 66 million years ago,” says geochemist Michael Henehan, from the GFZ German Research Centre for Geosciences. “Before the impact event, we could not detect any increasing acidification of the oceans.”

“The ocean acidification we observe could easily have been the trigger for mass extinction in the marine realm,” says geologist Pincelli Hull, from Yale University in Connecticut.

While scientists have suspected for years that the asteroid impact would have triggered a decrease in ocean pH (an increase in acidity) thanks to the explosion of sulphur-rich rocks and subsequent acid rain, it was the discovery of a particularly abundant collection of fossils that have helped to confirm it.


The team studied samples from a thick fossil seam left by foraminifera – tiny plankton that grow calcite shells – in a cave in Geulhemmerberg in the Netherlands. By investigating the isotopes of the element boron (a pH indicator) in the shells left behind, the acidification around the time of the Cretaceous-Paleogene die-off was revealed.

“In this cave, an especially thick layer of clay from the immediate aftermath of the impact accumulated, which is really quite rare,” says Henehan.

“Because so much sediment was laid down there at once, it meant we could extract enough fossils to analyse, and we were able to capture the transition.”

dino acid 2The cave in Geulhemmerberg. (Michael Henehan)

The impact on the food chain would’ve been huge, affecting just about every other creature higher up in the chain. Organisms like foraminifera could no longer survive, the life forms that fed on them would’ve been killed off too, and so on. The ocean’s role as a carbon sink would’ve been vastly reduced as a result.

This study also answers some long-standing questions about whether the asteroid impact almost completely killed off ocean life, or whether some species (of smaller plankton, for example), were able to survive. It’s a bit of both, the new research says.


In other words, a major loss of species to begin with, as much as 50 percent, followed by a transitional recovery period. That might give experts some fresh clues about how marine life started to flourish again – a process that took millions of years.

The study has plenty of relevance for us today, too: while there might not be any giant asteroids on the radar, increasing carbon dioxide emissions are leading to subsequent increases in ocean acidity.

As the foraminifera fossils show, that puts future life on this planet on shaky ground – the burning of coal, oil and gas could lead to a pH dip greater than the one 66 million years ago, the researchers say, though it’s important to point out that a lot of different factors are at play.

“When the asteroid struck, atmospheric CO2 was naturally already much higher than today, and the pH much lower,” environmental scientist Phil Williamson from the University of East Anglia in the UK, who wasn’t involved in the study, told The Guardian. “Furthermore, large asteroid impacts cause prolonged darkness.”

“Nevertheless, this study provides further warning that the global changes in ocean chemistry that we are currently driving have the potential to cause highly undesirable and effectively irreversible damage to ocean biology.”

The research has been published in PNAS.


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