Marine Life Can Buffer Ocean Acidity, Study Finds

By Christie Wilcox | January 16, 2018 8:00 am
Tide pools reveal surprising influence of marine life on seawater chemistry. Photo Credit: Ethan Daniels/Shutterstock

Tide pools reveal surprising influence of marine life on seawater chemistry. Photo Credit: Ethan Daniels/Shutterstock

One of the many consequences of rising atmospheric carbon dioxide is ocean acidification—the lowering of seawater pH as CO2 chemically reacts with dissolved ions in seawater. Scientists have found that more acidic waters are dangerous to many species, especially structure-builders like corals, and thus the potential drop in pH predicted in the future would be devastating to marine habitats.

So it’s not surprising that many scientists are actively looking for ways to mitigate this for coastal ecosystems, where losses could be especially impactful ecologically and economically. But the answer may be right in front of them: marine life is already able to buffer drops in pH, finds new research in Scientific Reports.

“Our research shows that marine life plays a substantial role in controlling the level of acidity, or pH, along the coast just by breathing or photosynthesizing,” said Nyssa Silbiger, an assistant professor in the Department of Biology at California State University, Northridge and lead author on the new study. “Marine plants and algae increase pH in the seawater right next to them, making it more basic, while animals make it more acidic.”

“This is an exciting result because it shows that marine life not only respond to changes in pH, but that they actually play a major part in controlling it,” Silbiger said.

All Aboard the Bio Bus

Most work on ocean acidification has tested how organisms fare when exposed to the magnitude of pH shift predicted by models. But those predictions are for average changes to seawater worldwide. “It’s all based on open ocean, stable conditions,” Silbiger explained. “But coastal ecosystems are so different.”

In her prior work on coral reefs, she observed the pH of seawater changing by an order of magnitude over distances smaller than a football field, for example.

So to examine how these systems are affected by swings in pH, Silbiger (then a postdoc at University of California, Irvine) took to the Pacific coast with UC Irvine PhD student Piper Wallingford aboard the Biology Bus—a 2002 Eurovan Winnebago named Becky donated by GoWesty! which the team outfitted for research. The pair traveled 1,300 miles  from San Diego, California to the Olympic Coast of Washington, stopping to conduct fieldwork for their projects along the way. “We lived for two months in this van, road-tripping from tide pool to tide pool,” Silbiger said. “It was great because we’d just pull up to the beach to conduct 24 hour experiments, and in between time points, we’d sit in the back and eat French toast in the van.”

Silbiger, Wallingford and Becky the Biology Bus. Photo Credit: GoWesty

Wallingford (left), Silbiger (right) and Becky the Biology Bus. Photo Credit: GoWesty

Shoreline Laboratories

Instead of setting up tightly controlled lab experiments to see how communities respond to acidity, Silbiger took advantage of the isolated-yet-not nature of tide pools. “You basically have this little individual ecosystem that you can work with and manipulate,” she explained. At low tide, each pool is essentially separated from the rest of the ocean, which means any changes are quantifiable and “due to the organisms or the physics that are happening right then inside that tide pool.”

Silbiger collected detailed data on 57 tide pools across four sites along the Pacific coast. For each pool, she measured physical details like the size and depth of the pool and how near it sat to the water’s edge. She also carefully cataloged the biological community in the pool, from algae to fish, categorizing them as producers—organisms able to take sunlight and carbon dioxide to create the building blocks of life, increasing pH in the process—and consumers, whose only decrease pH as they respire. And then, hourly water samples were taken to track the pools’ chemical traits, including pH.

Around the clock fieldwork was intense, said Silbiger. Photo Credit: Nyssa Silbiger.

Around the clock fieldwork was grueling, said Silbiger. Photo Credit: Nyssa Silbiger

Silbiger was surprised that the life in the pool was the most important determinant of its acidity. While physical variables controlled the general patterns of rise and fall, the amount a pool changed was due to the critters. “The biology alone is driving that variability,” she explained. The more algae and other producers in the pool, the greater the difference between daytime high pHs, when photosynthesis was at its maximum, and nighttime low pH, when no photosynthesis was occuring.

But that wasn’t the only surprise. When Silbiger examined the variability between pools at each site, she found that pools with extremely variable acidity, which had some of the most corrosive, lowest pHs at night, actually had more structure-building, calcifying organisms like mussels. She deduced that these animals are actually taking advantage of the incredible swings in pH created by their pool’s producers to grow during the day and resist erosion at night. “This cycle is called a “biophysical feedback loop”, where the organisms and the environment both influence each other,” she explained. “Animals that are growing shells or calcified skeleton can grow faster if they are in a location with lots of marine plants or algae.”

Natural Buffers

The work opens up the intriguing possibility of cultivating certain species to reduce impacts. “Algae might potentially be a buffer to ocean acidification on a very local scale,” said Silbiger. “There are studies going on where people are taking things like kelp and putting them offshore of oyster hatcheries and other farms like that to see if they can change the offshore chemistry just by adding these photosynthesizers.” Similarly, we might be able to cultivate seagrass beds inshore of coral reefs to buffer corrosive waters without exposing corals to their algal nemeses.

But mostly, the study shows just how important coastal conservation efforts are. “Our research shows that preserving locations with lots of marine plants and algae could locally buffer, or slow down, some of the negative effects of ocean acidification,” says Silbiger. “This means that if humans alter the composition of marine life along our coastlines via climate change or coastal development, it will change local pH conditions and could worsen the effects of global ocean acidification.”

“Ongoing coastal protection is thus necessary in addition to global reductions in CO2 emissions, which is the number one most important way to protect our coastal resources,” she stated.


Citation: Silbiger & Sorte, 2018. Biophysical feedbacks mediate carbonate chemistry in coastal ecosystems across spatiotemporal gradients. Scientific Reports 8, 796. doi:10.1038/s41598-017-18736-6

CATEGORIZED UNDER: Ecology, More Science, select, Top Posts
  • Uncle Al

    mitigate this” The Southern Sea is unproductive outside the Drake Passage and Scotia Sea – absence of photosynthesis nano-nutrient iron. Oceans acidify as more CO2 dissolves.

    Bayer process bauxite to pure alumina produces 77 million tons/year of “red mud,” micronized iron oxide in pH 13 water. Erect spray towers (and wind power generators) along Macquarie Island’s southeast coast. The Furious 50s and the Antarctic Circumpolar Current blow and row sustainable 10 billion gallons/year of red mud east. Phytoplankton, zooplankton, krill, then fish will gorge. Feed the world. Sequester carbon as oceanic feces sink. Ocean pH rises. Huge waste lagoons are recycled.

    Antarctic Circumpolar Current transport is (100 – 150)×10^6 metric tonnes/second, 26 – 40 billion gallons/sec. Each kilogram of iron nanofertilization fixes 83,000 kg of carbon dioxide then 100,000 kilograms of plankton, DOI:10.1016/0304-4203(95)00035-P. Injecting 50 million tonnes/year red mud conservatively removes 20 trillion tonnes/year of CO2 from the air. Burn all the coal you want.

  • OWilson

    Humans are just scratching the surface of some of the wondrous mechanism mother nature has in place to balance the planet, as a perfect home for life as we know it!

    Beware of good intentioned, but dangerously impulsive, human “helpers”!

    • Kurt S

      1. Its not a winnebago, its a converted minivan.
      2. Lets dismiss their work because they used a minivan?

      Until we make conversions to more sustainable alternatives to our personal transportation, does that mean we should suspend important research? They found absolutely good news to our oceans (at least locally in tide pools) that there is hope of sustaining viable ecosystems in the face of acidification from the atmosphere!

      • John Thompson

        So we can’t point out their hypocrisy?

  • Doğukan Şahin

    great post

  • TheAxial

    Thanks for your beautiful sharing

  • John Thompson

    And just think – they are just beginning to understand a little bit about this key factor in the world’s ocean ecosystem.
    No one knows the exact way the atmospheric CO2, Calcium Carbonate marine cycle will work out.
    Yet they make predictions even not knowing.
    Clearly life can adapt in ways we do not even know yet.
    More CO2 would mean more algae growth – which would work to minimize any increased acidity.
    Save the doom and gloom predictions until we actually understand it.

  • stevenearlsalmony

    The Human Predicament: One voice from the wilderness is too weak to be listened to. My voice, for example, is not clear enough, strong enough, loud enough or adequately established so as to be heard. How can any person in a position of influence among our most wealthy and powerful leaders possibly be expected to receive a ‘best available science message’ until we and others who are similarly situated speak out, as if with one voice, about what could be somehow real, according to the best available science and ‘lights’ we possess?

    Declining fertility rates virtually everywhere on Earth need not blind us to the undeniable, ongoing annual increases of absolute global human population numbers. Human numbers have exploded by more than 5 billion on earth in the past three score and ten years. This population growth ‘trajectory’ is patently unsustainable on a planet with the size, finite resources and frangible ecology of Earth. Please consider how the growth of human numbers worldwide is caused by the spectacular production and distribution of food for human consumption. With each passing year more people are being fed and more people are going hungry.

    For years we have been encouraged to “think globally.” Let us hope that it is not too late to begin “acting globally.” There is not time to waste because untethered overproduction, overconsumption and overpopulation activities of the human species are on the verge of causing a global ecological wreckage of the planet we inhabit by turning Earth’s land surface into mountains of human detritus and its seas into sewers.

    As things stand, the leading self-righteous elders in the world on our watch are charting a course to the future that will wreak havoc on what is surely sacred and normalize what is plainly profane…..come what may. And these self-proclaimed ‘masters of the universe’ erroneously believe that they can have some faraway island or mega-yacht to which an escape from the global ecological wreckage would be possible. More evidence of immaculate hubris, I suppose.

    Those few with power would like the status quo to remain as is; whereas, the many, too many, without power want necessary change and a “course correction” while a ‘window of opportunity’ remains open. Note to us all: the window is closing steadily in our time. When unbridled production, consumption and propagation activities of the human species are occurring synergistically, expanding rampantly and effectively overspreading earth, perhaps this moment in space-time is an occasion to do something that is different and somehow right … for a change.

    No one knows what is possible once we begin somehow to do things differently from the ways that we are doing things now here on our planet. At the moment we know that silence has overcome science; that greed has vanquished fairness and equity; that ignorance and stupidity have almost obliterated common sense and reason; that hubris has virtually annihilated humanness. Like it or not, ready or not, we are presented with enormous challenges.

    Let us hope that our most able responses to the human-induced and -driven existential ecological threats looming ominously before humanity do not come too late to make a difference that makes a difference. There is much to do. Human limits, global planetary limitations and time constraints are the factors to which we are called upon to respond ably with all deliberate speed.

    If only the world worked the way we want it to! That all-too-human creatures of Earth were actually self-proclaimed ‘masters of the universe’ in more ways than “name only.” By evading extant scientific knowledge about our distinctly human creatureliness and the biophysical limitations of the planet we inhabit; by widely sharing and consensually validating utterly false, hubristic thinking regarding our seemingly god-like super-human capabilities and Earth as a maternal presence … imagined as an eternally expressive teat; by denying that earth is relatively small and finite with a frangible environment, it may be that the human community is not able to evade the consequences of our patently unsustainable behavior. Can we rise above our apparent incapacity to respond ably or not? Can we do so in a short time-frame so we avoid insurmountable “doomsday scenarios”?

    Note the exquisite talents demonstrated by the savants among us or the teachers, poets, artists from whom there emanates universally shared, humane values, principles and practices for living or the leaders who have not sold out their souls for the poisoned fruits of power, gluttony, greed, wrath, pride, envy and effortless ease. The global challenges presented to our generation of elders are likely different from the threats to human well being that had to be confronted by our ancestors. But that does not mean, even for a moment, that their challenges were either more or less difficult from the ones we face.

    If our ancestors had not acknowledged, addressed and overcome the challenges before them, I dare say that we would not be here now. It does not appear that our generation of elders has so much as begun to struggle in a meaningful way with the global challenges before us. We collectively have been running away from our responsibilities and duties to the family of humanity and Earth’s well being in general.

    Our children and their children after them will say that we have failed them. Their true statement, perhaps spoken some day soon as a refrain, is not acceptable and cannot become our enduring legacy to life on this planet and to the planet, itself. We cannot luxuriate in our willful ignorance and self-serving hysterical blindness any longer.

    The moment to step up, take hold, and move forward courageously is at hand. The time has come to accept the challenges already dimly visible in the offing. Let us speak out as if we are a million voices because so many of us remaining electively mute make us complicit in the destruction of Earth and life as we know it. Are better, more responsible courses of action available to us? If so, other ways of going forward need to be discovered, discussed and implemented, fast.


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About Christie Wilcox

Dr. Christie Wilcox is a science writer based in the greater Seattle area. Her bylines include National Geographic, Popular Science, and Quanta. Her debut book, Venomous, released August 2016 (Scientific American/FSG Books). To learn more about her life and work, check out her webpage or follow her on Twitter, Google+, or Facebook.


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