19. Ocean Acidification

A recent study published in “Nature Change” found that 80% of Britons have never heard of ocean acidification. Probably in the U.S., where a whole industry is devoted to keeping citizens in the dark about climate change, the percentage is even worse. But this is the issue that ocean scientists say keeps them up at night.
Since the dawn of the industrial revolution in the nineteenth century, the oceans have absorbed almost half of the CO2 that has been spewed into the atmosphere. This year alone the oceans will absorb approximately two and a half billion tonnes of carbon. For us land-based air-breathers this could be seen as a good thing, for otherwise we would be really feeling the heat. However, this absorption of CO2 has resulted in the oceans becoming warmer and approximately 30% more acidic.
The most common measure of the acid/alkali ratio of seawater is the pH scale in which 7.0 is neutral, more than 7.0 is alkaline, and less than 7.0 is acidic. It is a logarithmic scale, which means that a change is multiplied by some factor. For example, a decrease in pH from 8.3, (which was the level of seawater before the industrial revolution began), to 8.2 (the average today) is an increase in acidity of 30%. Actually, the change is a decrease in alkalinity, but Ken Caleira and Michael Wickett, the two scientists who first coined the term “ocean acidification” wanted to alert us to what is happening. By 2100, unless emissions are reduced from current levels, an increase of 150% is predicted.
Ocean life has not experienced such a rapid shift in the last 20 million years. The biggest shift in acidity occurred about 250 million years ago during the Permian-Triassic Extinction Event, also known as the Great Dying. The latest findings reported by Stanford University in 2010, indicate large volcanic eruptions spewed out lava flows that caused massive coal deposits to burn uncontrollably, releasing huge quantities of CO2. This may have also triggered a sudden release of methane gas from the sea floor. The situation today has some parallels to that event, although it is thought that the increase in GHGs today is happening much faster than 250 million years ago. During that period approximately 96% of all marine species perished.
The chemistry of “acidification” goes like this. As CO2 is absorbed in the water it combines with hydrogen to form a weak acid, carbonic acid, which you can find in Coke. (H2CO3). This readily breaks down into bicarbonate (HCO3) plus free H+ ions, which causes the increased acidity. Organisms that form shells need to combine carbonate (C03) with calcium to form calcium carbonate (CaCO3). However, because bicarbonate is more stable than carbonate these organisms experience a dearth of carbonate. The amount of calcium remains constant, but the process of combining calcium with carbonate slows down or stops. When this happens shells either stop forming or begin to corrode.

The plasma in our blood (the watery part) is similar in its concentration of salt and other ions to seawater. Imagine if we were subjected to a slow infusion of acid into our blood plasma while at the same time our red and white blood cells were reduced so that less oxygen could be transported to our various organs and our immune system became compromised. All of this is happening to life in our planet’s oceans. CO2 is increasing acidity; anoxic zones are expanding and we are mining vast quantities of marine organisms and fish. If the poison were introduced gradually, we might not at first feel the symptoms. Then, when we did start to suffer, we might not understand the cause. But we would know we were not feeling well. We might put off seeing the doctor or perhaps not bother to take the prescribed medicines. If left untreated there would come a time when we would become really ill and in danger of dying. Even then we likely wouldn’t know for sure whether we had passed that point of no return. This is our situation today. The Arctic is melting rapidly, forests are burning and exposing permafrost. 90% of predator fish have been eliminated. Are we passed the point of no return? When some people find themselves in this situation they give up. Others fight to live. The choice is ours.
The most obvious victims of acidification are shell-forming organisms such as oysters, sea urchins, sea cucumbers, crabs, scallops, and coral. Because cold water absorbs CO2 more readily than warm water, the Arctic and Antarctic areas are most severely affected.

In 2009 French oceanographer, Professor Jean-Pierre Gattuso, of the Centre national de la recherche scientifique, told an international oceanography conference concerning acidification of the Arctic, “This carbon dioxide dissolves and is turned into carbonic acid, causing the oceans to become more acidic. We knew the Arctic would be particularly badly affected when we started our studies, but I did not anticipate the extent of the problem”. His research suggested that 10% of the Arctic Ocean would be corrosively acidic by 2018; 50% by 2050; and 100% by 2100. “Over the whole planet, there will be a threefold increase in the average acidity of the oceans, which is unprecedented during the past 20 million years. That level of acidification will cause immense damage to the ecosystem and the food chain, particularly in the Arctic,” he added. [1]
It is unlikely that ocean life will have time to adapt to acidification, because it is happening “100 times faster than any changes in prior millennia”.[2]

Fin fish are affected too. In Sweden, British researcher, Jonathan Havenhand, has demonstrated that ocean changes “could impede the most fundamental strategy of survival: sex.” That is because acidity causes sperm to swim slower, reducing the number of fertilized eggs. Other effects include behavioral problems such as young cod swimming towards prey, rather than away from it. Most fish can withstand some change in pH levels, but this requires energy that is not available for survival and reproduction. Fish may attempt to buffer low pH with their gills. Very young fish do not yet have gills, and they are particularly susceptible. Some species are more susceptible to temperature changes with increased acidity.
Higher acidity also disrupts marine organisms’ ability to grow, reproduce and respire. The Census of Marine Life reported that phytoplankton, the microscopic plants producing most of the oxygen from the oceans, have been declining by around 1% a year since 1900.
 

Castello Aragonese,Italy 40.731, 16.965
Castello Aragonese is a tiny island off the west coast of Italy. There is a castle there with a display of medieval torture equipment.
Just offshore there are undersea vents that splay out almost 100% carbon dioxide. In her excellent book, “The Sixth Extinction”, Elizabeth Kolbert describes her dive there with researchers, Hall-Spencer and Buia.
“The water is frigid. Hall-Spencer is carrying a knife. He pries some sea urchins from a rock and holds them out to me. Their spines are an inky black. We swim on, along the southern shore of the island, toward the vents. Hall-Spencer and Buia keep pausing to gather samples-corals, snails, seaweeds, mussels-which they place in mesh sacs that drag behind them in the water. When we get close enough, I start to see bubbles rising from the sea floor, like beads of quicksilver. Beds of seagrass wave beneath us. The blades are a peculiarly vivid green. This, I later learn, is because the tiny organisms that usually coat them, dulling their color, are missing. The closer we get to the vents, the less there is to collect. The sea urchins drop away, and so, too do the mussels and the barnacles. Buia finds some hapless limpets attached to the cliff. Their shells have wasted away almost to the point of transparency. Swarms of jellyfish waft by, just a shade paler than the sea. “Watch out”, Hall-Spencer warns, “They sting.”
The researchers note that these vents have been spewing CO2 for hundreds of years, and there is no indication that any organisms have adapted to the acid conditions. When the pH gets as low as 7.8 the number and variety of species declines markedly, and the ecosystem starts to crash. Until recently this was expected to happen around 2100. Now we realize that it is happening much sooner.

 

Netarts Bay,WA 45.421, -123.936
My interest was further piqued in 2007 when I read about a disturbing loss of oysters along the west coast of North America. In that year two oyster farmers at their Whiskey Creek Shellfish Hatchery in Tillamook, Oregon found that their oysters were dying. Mark Wiegardt and Sue Cudd at first didn’t know what was wrong. Could it be bacterial infection? Water temperature? All they knew was that their oysters started dying in mass. Desperate, they turned to oceanographer Burke Hales and his team from Oregon State University. They learned that the Pacific water piped into their tanks from Netarts Bay was too acidic, and the young larvae were unable to grow shells. Without shells they died. This phenomenon was soon reported along the coast, including Dabob Bay, Puget Sound in Washington State and Canada’s Baynes Sound, off the east coast of Vancouver Island. The oyster farmers learned that they had to measure the pH of the water before piping it into their tanks and either wait until the acid level dropped or remove excess CO2 from the water.
At that time there was very little information on ocean acidification, so I started collecting articles and information on it and its causes. I learned that during the summer, the strong westerly winds that push against the west coast cause strong upwellings of ocean water. This deeper, colder water is more acidic than surface waters. The upwellings occur just as oyster and other shellfish larvae are hatching. Since 2007 the number of severe die-offs of shellfish has been increasing markedly.
 

Tatoosh Island, WA 48.392, -124.738
Over the last 20 years two biologists, Cathy Pfister and her husband, Tim Wootton, have been traveling to Tatoosh Island off the northwestern tip of Washington State and studying the marine life there, as well as measuring pH levels.
In 2008 they published findings that showed that pH levels were declining at a rate 10 times faster than predicted. They have since published findings showing acid levels went from pH 8.3 in 2000 to 7.8 in 2010. This is a very serious drop which they attributed to increased ocean absorption of CO2 from the air.
After they published these findings some scientists suggested other causes for such an extreme drop. Among these were changing currents that could flush Fraser River water out to Tatoosh Island; changing ocean currents causing more upwelling; increased rainfall, and eutrophication [3] caused by an increase of nutrients. Pfister and Wootton could find no evidence to support any of these explanations.
As a side note, my readings with my two pH meters in the Canadian Gulf Islands have shown a pH as low as 7.8, especially in summer. Certain areas average lower than others. During this time the Canadian federal government was very hostile to climate research and closed down many marine studies while throttling scientists who dared to speak out. This was a very dark time for Canadian science, and we had to rely on U.S. studies to try to understand acidification. Then during the Trump years, the situation was reversed and the fossils in Washington were doing their best to hold back ocean climate science. If seems that the scientists are making a comeback now.

Pteropods are tiny snail-like creatures measuring from 3mm to 12mm that grow shells to protect their bodies. Also known as sea butterflies because of their beautiful shape, these creatures are an important part of the marine food chain. They make up an estimated 60% of the diet of pink salmon in the first year of their life. Because pteropods grow shells they are sensitive to acidic water. It was thought that we might see evidence of dissolving pteropod shells sometime around 2038. However, it is already happening off the west coast of North America, and in the Antarctic.
Nina Bednarsek, who first found corrosion in pteropod shells in Antarctica, and who was affiliated with the British Antarctic Survey, has led a study that has found significant corrosion of the shells of pteropods off the west coast of North America. The damage so far wasn’t enough to kill the animals, but it did weaken them and made them vulnerable: “From a combined survey of physical and chemical water properties and biological sampling along the Washington-Oregon-California coast in August 2011, we show that large portions of the shelf waters are corrosive to pteropods in the natural environment.”[4]
“What we found was just amazing to us, said Richard Feely, a scientist with the National Oceanic and Atmospheric Administration’s Pacific Marine Environmental Laboratory. We did the most extensive analysis” [5]. These copepods are “a great example of some tiny non-charismatic creature that is incredibly important,” said Gretchen Hofmann, a biologist and ocean-acidification expert at the University of California at Santa Barbara. “They’re small but carry an enormous amount of nutrition and are eaten even by very big fish. If you’re in the Antarctic and see a beautiful emperor penguin, it exists by eating fish under the sea ice. And those fish eat pteropods.” [6]
A similar result was found off the coast of California. “Habitat suitability for pteropods in the coastal California Current Ecosystem (CCE) is declining. We found 53% of onshore individuals and 24% of offshore individuals on average to have severe dissolution damage.” [7]
In the summer of 2015 pink salmon returning to the Pacific Northwest were much smaller than normal, and few in number. It was a disastrous return that was not expected. No one can say for sure why. In the past it has been thought that sea lice and viral infections from fish farms may be the cause. This remains a concern. However, this would not explain the sudden, precipitous drop.
Tests on pink salmon indicate that the young are not fearful of threats in acidic water. There is a reduction in olfactory response which affects their ability to detect predators. The harm to their olfactory senses may also affect their ability to recognize their natal streams.
 

There was a massive algae bloom off the coast for much of 2015. Imagine an undersized salmon that returns to its natal water but dies before it can spawn. Perhaps it got infected with a couple of extra sea lice on its way past the numerous salmon farms it must pass on its way out to the open sea. Then it had trouble finding enough of its main food source, the pteropods, due to acidification. It also had to expend extra energy buffering the effects of the acidic water. Later, it encountered a huge algae bloom caused by warming waters and runoff nutrients that depletes the amount of oxygen in the water and is poisonous to the small forage fish it feeds off. Finally, because of reduced snow melt from glaciers in full retreat, in a weakened state it encountered water that is too warm. What killed this fish?

The corrosive effect of acidic water on pteropods was first noticed, quite by accident, by Victoria Fabry, an oceanographer at California State University at San Marcos. She began collecting pteropods for study in one litre jars in 1985. When she put more than just two or three in the same jar, she noticed that the shells became opaque. It was some years later, however, when she went back to her samples and examined them under a microscope, that she found their shells were pitted and, in some places, worn away. Like all animals, the pteropods take in oxygen and expel CO2. When she overpopulated her glass jars, the water became more acidic and began corroding the shells of the tiny creatures. At the time no one realized that the chemistry of the whole ocean could be impaired by human activity, but we sure do now. It still amazes me that we humans are changing the chemistry of all the world’s oceans, and indeed polluting them, at an unprecedented rate, at least in the past 300 million years, and that this rate is far too fast for most marine organisms to adapt. It will take tens of thousands of years just for the oceans to return to a chemical state similar to that before industrial times. Even if we were to stop carbon pollution today the oceans will continue to absorb CO2 from the atmosphere until a new balance is achieved.
 

In 2008, Dr. Kawaguchi, a marine biologist who works for the Australian government’s Antarctic Division, conducted similar experiments to those Victoria Fabry had done in 1985, except that his jar was filled with krill eggs immersed in CO2-laden seawater. He found that the CO2 killed the eggs. He was surprised at such a clear result and had thought that the krill might have been more robust.
Kawaguchi has been studying krill for more than 25 years and has the only research tanks in the world dedicated to breed and study krill. Dr. Kawaguchi predicts a 20% to 70% reduction in krill by 2100. Dr. Kawaguchi was the lead author in a study titled “Risk maps for Antarctic krill under projected Southern Ocean acidification” published by Nature Journals.
Krill are shrimp-like crustaceans from 1 to 15 cm in length that “are essentially the fuel that runs the engine of the Earth’s marine ecosystems.” (National Geographic) Such a decrease in the krill population would be a disaster for all of the fish and their predators, such as penguins, seals and whales, dolphins, seabirds and human fishers.
Recent studies show that Antarctic krill stocks may have dropped by 80% since the 1970s. Part of the loss may be explained by the loss of sea ice and hence, ice algae, due to global warming. Krill feed mainly on phytoplankton, microscopic, single-celled plants. In polar regions, to avoid predators, they often feed on the ice algae that congregate directly under the sea ice.
Young salmon are quite susceptible to acidification. In Norway, 18 stocks of Atlantic salmon are extinct and another 8 are threatened due to acid rain. The Norwegians have been spreading lime on 21 rivers and have had some success, although one study concluded that 20 years of liming is required to restore stocks.
Coral reefs are composed of diverse colonies of tiny polyps that secrete a form of calcium carbonate called aragonite to form the shell structure. Each polyp is a complete individual, but thousands and thousands are joined together over the skeleton to make a reef. They are the most diverse of all marine ecosystems and are home to an estimated 25% of all marine fish species. It has been estimated that there are from one million to nine million species that live on or near coral reefs. It is amazing that this estimate is so broad, that a guess on the number could miss by several million. Since each species would have multiple relationships with other reef members, there must be millions and millions of contacts, alliances and predations that we know nothing about.
 

Coral reefs have been dying in record numbers over the last few years. Charlie Veron[8] has discovered more than 20% of the world’s coral species and has lived and worked on the Great Barrier Reef, the world’s largest coral system, for most of his life. He “finds himself in the agonizing position of having to be a prophet of its extinction.” We cannot wonder that he feels “very very sad. It’s real, day in, day out, and I work on this, day in, day out. It’s like seeing a house on fire in slow motion…and you have been for years.” [9]
 

The Great Barrier Reef off the east coast of Australia has lost one half of its cover in the last 27 years, with a yearly loss of 3.4%. Causes listed are crown of thorn starfish that eat coral, increased agricultural runoff from massive storms, tropical cyclones of increasing frequency and ferocity, and ocean warming and acidification. Some experts believe that if the starfish can be eliminated the reef could be rejuvenated over the next two or three generations. Recently an underwater drone has been developed that can autonomously recognize crown-of-thorn starfish and inject poison into them. However, this is seen as just a temporary holding measure.
 

Les Kaufman is a biologist at Boston University and is part of an international consensus statement on climate change and coral reefs. In order to save the reef, or what’s left of it, he states, “International efforts to cap and reduce CO2 emissions are equally critical and must occur at the same time as cleaning up local impacts.” He continues, “There is absolutely no excuse for failure to do this, and if we do fail, our generation will forever be remembered for unimaginable, unforgivable stupidity and sloth.” [10]
 

It is difficult to imagine a more disastrous threat to life in the oceans than the extinction of shell fish, pteropods and krill due to ocean warming and acidification. Many scientists think that we are in, or about to enter, the sixth mass extinction, which parallels the Great Dying, 250 million years ago. One of the biggest concerns is that the oceans are acidifying faster than at any time in history and marine stocks simply will not be able to adjust. The other concern is that the ocean will continue to absorb CO2 from the atmosphere long after we stop polluting the air. “Alarmingly, the pH drop observed is 100 times faster than any changes in prior millennia. Left unchecked, CO2 levels will create a very different ocean, one never experienced by modern species.” [11]
 

There is a time lag. By the time we experience the full impact of marine extinction it may well be too late. This acidification is ongoing, relentless, undeniable, and, even if we stop releasing GHG gases, unstoppable. There may be still time, though, to reduce the negative effects of acidification. We must try. A lot of political and industry leaders say we can continue building pipelines and expanding fossil fuel production while “caring” for the environment. But there is no such middle ground. This is an emergency situation that requires an emergency response.
[1] (Robin McKie, science editor, the guardian, October 4/2009) http://www.theguardian.com/world/2009/oct/04/arctic-seas-turn-to-acid
[2] Scientific American, August, 2010
[3] Excessive nutrients in a lake or other body of water, usually caused by runoff of nutrients (animal waste, fertilizers, sewage) from the land, which causes a dense growth of plant life; the decomposition of the plants depletes the supply of oxygen, leading to the death of animal life. (Vocabulary.com Dictionary)
[4] NOAA study reported in the Proceedings of the Royal Society, May 1, 2014
[5] reported in the Vancouver Sun, May 1, 2014
[6] Seattle Times, Nov 25, 2012.
[7] NOAA study reported in the Proceedings of the Royal Society, May 1, 2014
[8] Dr. Charlie Veron is a prominent marine scientist known as the ‘Godfather of Coral,’ having discovered 20 percent of all coral species in the world. He has worked in all the major coral reef regions of the world, participating in 66 expeditions, and spending 7,000 hours scuba diving. Veron was formerly the Chief Scientist of the Australian Institute of Marine Science and has authored over 100 scientific articles, including 14 books and monographs. He has been the recipient of the Darwin Medal, the Silver Jubilee Pin of the Australian Marine Sciences Association, the Australasian Science Prize, the Whitley Medal and received special mention in the Eureka Awards. Today he continues to work in many different fields although he concentrates on conservation and the effects of climate change on coral reefs. He predicts that if humanity continues to produce carbon dioxide at present rates, coral reefs will vanish in the next few decades. (http://therevolutionmovie.com/index.php/biography/dr-john-charlie-veron/)
[9] (Scientific American, May 2014)
[10] Katharine Gammon, LiveScience Contributor, Oct 1/2012, LiveScience
[11] (Scientific American, August, 2010)