“Nobody expected that it could do something so bizarre..”

September 1, 2015


I’ve heard that line in a horror movie or two..

Greg Laden’s Blog:

I’ve got a press release from the University of Southern California that seems important, but I don’t have time today to read the study. So, you can look at the press release and tell me what you think of it.

Climate Change Will Irreversibly Force Key Ocean Bacteria into Overdrive

Scientists demonstrate that a key organism in the ocean’s foodweb will start reproducing at high speed as carbon dioxide levels rise, with no way to stop when nutrients become scarce

Imagine being in a car with the gas pedal stuck to the floor, heading toward a cliff’s edge. Metaphorically speaking, that’s what climate change will do to the key group of ocean bacteria known as Trichodesmium, scientists have discovered.

Trichodesmium (called “Tricho” for short by researchers) is one of the few organisms in the ocean that can “fix” atmospheric nitrogen gas, making it available to other organisms. It is crucial because all life — from algae to whales — needs nitrogen to grow.

A new study from USC and the Massachusetts-based Woods Hole Oceanographic Institution (WHOI) shows that changing conditions due to climate change could send Tricho into overdrive with no way to stop — reproducing faster and generating lots more nitrogen. Without the ability to slow down, however, Tricho has the potential to gobble up all its available resources, which could trigger die-offs of the microorganism and the higher organisms that depend on it.

By breeding hundreds of generations of the bacteria over the course of nearly five years in high-carbon dioxide ocean conditions predicted for the year 2100, researchers found that increased ocean acidification evolved Tricho to work harder, producing 50 percent more nitrogen, and grow faster.

The problem is that these amped-up bacteria can’t turn it off even when they are placed in conditions with less carbon dioxide. Further, the adaptation can’t be reversed over time — something not seen before by evolutionary biologists, and worrisome to marine biologists, according to David Hutchins, lead author of the study.

“Losing the ability to regulate your growth rate is not a healthy thing,” said Hutchins, professor at the USC Dornsife College of Letters, Arts and Sciences. “The last thing you want is to be stuck with these high growth rates when there aren’t enough nutrients to go around. It’s a losing strategy in the struggle to survive.”

Tricho needs phosphorous and iron, which also exist in the ocean in limited supply. With no way to regulate its growth, the turbo-boosted Tricho could burn through all of its available nutrients too quickly and abruptly die off, which would be catastrophic for all other life forms in the ocean that need the nitrogen it would have produced to survive.

Some models predict that increasing ocean acidification will exacerbate the problem of nutrient scarcity by increasing stratification of the ocean — locking key nutrients away from the organisms that need them to survive.

Hutchins is collaborating with Eric Webb of USC Dornsife and Mak Saito of WHOI to gain a better understanding of what the future ocean will look like, as it continues to be shaped by climate change. They were shocked by the discovery of an evolutionary change that appears to be permanent — something Hutchins described as “unprecedented.”

“Tricho has been studied for ages. Nobody expected that it could do something so bizarre,” he said. “The evolutionary biologists are interested in it just to study this as a basic evolutionary principle.”

The team is now studying the DNA of Tricho to try to find out how and why the irreversible evolution occurs. Earlier this year, research led by Webb found that Tricho’s DNA inexplicably contains elements that are usually only seen in higher life forms.

“Our results in this and the aforementioned study are truly surprising. Furthermore, they are giving us an improved, view of how global climate change will impact Trichodesmium and the vital supplies of new nitrogen it provides to the rest of the marine food web in the future.” Webb said.

The research appears in Nature Communications on September 1.

The abstract of the study is here:

Nitrogen fixation rates of the globally distributed, biogeochemically important marine cyanobacterium Trichodesmium increase under high carbon dioxide (CO2) levels in short-term studies due to physiological plasticity. However, its long-term adaptive responses to ongoing anthropogenic CO2 increases are unknown. Here we show that experimental evolution under extended selection at projected future elevated CO2 levels results in irreversible, large increases in nitrogen fixation and growth rates, even after being moved back to lower present day CO2 levels for hundreds of generations. This represents an unprecedented microbial evolutionary response, as reproductive fitness increases acquired in the selection environment are maintained after returning to the ancestral environment. Constitutive rate increases are accompanied by irreversible shifts in diel nitrogen fixation patterns, and increased activity of a potentially regulatory DNA methyltransferase enzyme. High CO2-selected cell lines also exhibit increased phosphorus-limited growth rates, suggesting a potential advantage for this keystone organism in a more nutrient-limited, acidified future ocean.

We’re all looking at methane clathrates, and here comes this wild card…

UPDATE: Washpost has this:

Cyanobacteria might be most famous for the huge algal blooms they occasionally undergo if there happens to be an excess of the nutrients they feed on in the water. These blooms, which often produce red, blue or green stains on the surface of the water, are known for the harmful toxins they produce, which often drive away or kill off any marine animals in the area.

But despite these occasional incidents, cyanobacteria generally do much more good than harm. These tiny critters play an important role in the marine ecosystem by pulling nitrogen gas out of the water and converting it into a form that other organisms can use, a process known as “nitrogen fixation.”

Now, the new research shows that a type of cyanobacteria called Trichodesmium fixes nitrogen at much higher rates in a high-carbon environment. This reaction could have big implications for the marine food web because Trichodesmium is such a major player when it comes to nitrogen fixation. Found in tropical and subtropical parts of the ocean, it can be responsible for bringing in up to half the usable nitrogen in the areas where it lives, said Hutchins.

The paper also shows for the first time that these effects are irreversible — even when the bacteria were restored to lower carbon levels, their nitrogen fixation rates did not return to normal.

Previous research on cyanobacteria in high-carbon environments have included only short-term studies, Hutchins said. This study is the first to examine the effects of elevated carbon dioxide levels over a long period of time, an important step to understanding the long-term effects of climate change on the ocean.

This idea is made more alarming by the fact that the effects seem to be irreversible. After the 4.5 years were up, the researchers returned the bacteria to present-day carbon dioxide levels, assuming that their nitrogen fixation rates would also go back to normal. Instead, the bacteria continued to fix nitrogen at high rates — even two years later.

“No one has ever seen an organism do what this does, which is to get stuck — to evolve into a new space and then not be able to change back,” Hutchins said. The finding suggests that even if humans eventually curb our carbon emissions and carbon dioxide levels in the ocean start to decline, the bacteria may not return to their ordinary activity. For this species, at least, the effects of climate change appear to be permanent.

14 Responses to ““Nobody expected that it could do something so bizarre..””

  1. SmarterThanYourAverageBear Says:

    We are so screwed

    • dumboldguy Says:

      If you want to look at it from “the sky is falling” perspective,. yes, we MAY be screwed. Forcing evolution in simple organisms by subjecting them to laboratory conditions that MAY exist on the planet in 2100 is a nice trick, but those organisms may not evolve in the same ways in the real world.

      What is scary is what the abstract says about not being able to “undo” the results of the forced evolution—-as Hutchins said, “No one has ever seen an organism do what this does, which is to get stuck — to evolve into a new space and then not be able to change back”. Maybe it would be smart to NOT allow the planet to get to such a state that the real Tricho follows the experimental Tricho?

  2. Andy Lee Robinson Says:

    The logical thing would be to maintain a stock of unadapted Tricho and reintroduce when CO₂ levels come back down, but it won’t be easy keeping enough in storage for tens of thousands of years, and remain viable.

    • dumboldguy Says:

      The “logical” thing to do would be to keep the CO2 levels from rising in the first place. Yep, “…it won’t be easy keeping enough in storage for tens of thousands of years”. We have a number of seed repositories on the planet, and a lot of frozen “life stuff”, but the chances of human civilization keeping it all going over the time span of tens of thousands of years are minimal.

      Case in point. How much “storage” of viable life forms (or anything much else) did our ancestors of tens of thousands of years ago leave for us.

      (and “stocking” some Tricho in the future ocean and expecting it to spread planet-wide is a far cry from dumping a bucket of Bass in a pond).

  3. redskylite Says:

    Sea level rise sounded worrisome enough, specially at the higher levels that are possible as time goes by, forest depletion, CO2 sinks diminished all very bad news. But when you start talking about bacteria changing Earth’s natural chemical compositions irreversibly, because of climate change, it is really time to treat it seriously, (note to Rex W. Tillerson/Exxon chief ), even man cannot adapt to that.

    No wonder the deniers get uncomfortable and would rather institutions didn’t go there and stick to looking at Pluto and beyond instead. Paleontologists are well aware of chemical changes that have occurred way back in time , and ones with great literary skills have written some very good books, and whether you consider them non-fiction or fiction is dependent on the regard you have for their skills. That reminds me it’s time to buy a book, Under a Green Sky, by Peter D Ward, would be a good bet.

    Pretty good style for a scientist . .

    “The land is hot barrenness.

    Yet as sepulchral as the land is, it is the sea itself that is most frightening.
    Waves slowly lap on the quiet shore, slow-motion waves with the consistency of gelatin. Most of the shoreline is encrusted with rotting organic matter, silk-like swaths of bacterial slick now putrefying under the blazing sun,
    Finally, we look out on the surface of the great sea itself, and as far as the eye can see there is a mirrored flatness, an ocean without whitecaps.
    Yet that is not the biggest surprise.
    From shore to the horizon, there is but an unending purple color—a vast, flat, oily purple, not looking at all like water, not looking like anything of our world.
    No fish break its surface, no birds or any other kind of flying creatures dip down looking for food.
    The purple color comes from vast concentrations of floating bacteria, for the oceans of Earth have all become covered with a hundred-foot-thick veneer of purple and green bacterial soup.
    At last there is motion on the sea, yet it is not life, but anti-life.
    Not far from the fetid shore, a large bubble of gas belches from the viscous, oil slick-like surface, and then several more of varying sizes bubble up and noisily pop. The gas emanating from the bubbles is not air, or even methane, the gas that bubbles up from the bottom of swamps—it is hydrogen sulfide, produced by green sulfur bacteria growing amid their purple cousins.
    There is one final surprise.
    We look upward, to the sky.
    High, vastly high overhead there are thin clouds, clouds existing at an altitude far in excess of the highest clouds found on our Earth.
    They exist in a place that changes the very color of the sky.
    We are under a pale green sky, and it has the smell of death and poison”

    Seems to beat authors Arthur C. Clarke, Isaac Asimov, J.G Ballard, Frank Herbert and Frederick J. Pohl, because it is very rich in the past evidence .

    • dumboldguy Says:

      Peter Ward has written some good stuff, but “…for the oceans of Earth have all become covered with a hundred-foot-thick veneer of purple and green bacterial soup…” is a bit of hyperbole and overreach. The blanket would smother itself long before it got to be 100 feet thick. Ward should stick to the science that he is good at, and leave the science fiction to the fiction writers.

      If anyone wants to read a good book that is long on science and short on hyperbole, try Deep Future: The next 100,000 Years of Life on Earth, by Curt Stager.

      • Lionel Smith Says:

        The blanket would smother itself long before it got to be 100 feet thick.

        I hear where you are coming from but against that I offer stromatolites – the organisms that created these did not appreciate that the atmospheric balance of gases that they were creating was to their own future detriment.

        Funny isn’t it – the likes of Tillerson are displaying a similar level of intelligence as those blue-green algae of those Eons back in the Neo-Proterozoic.

        • dumboldguy Says:

          Yep, stromatolites are very cool and have their own significance, but what Ward is talking about is way beyond even the apples and oranges surface similarities with “blankets”.

  4. redskylite Says:

    Great piece of writing in wired.com today, thinking in deep time, which makes today’s events seem pretty short term and surreal, after all Svante Arrhenius published his paper (On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground) in 1896, and despite a 97% consensus the science still being denied, suppressed and ignored today. What is most worrying is some of the deniers are standing for high office in the most influential country of the world (and I don’t mean China). So many are just focused in the near time and pay no heed to beyond end of this current century … this article explores further. .

    “We’re like cockroaches,” Dick says. “I think we’ll stick around. We’ll see the disaster we’ve created.” But the recovery? Maybe not. For the oceans to adapt to the new climate and regain a level of productivity they enjoy today, “it’s not going to be in a few generations,” Nagelkerken says. “You could wait around for 10,000 years.”


    • dumboldguy Says:

      A great article, but I would quarrel with “We’re like cockroaches…I think we’ll stick around”. That’s glib and a cliche—-we are most assuredly NOT “like cockroaches”, and the “we” that “sticks around” will likely be at most a billion or so humans who will live in a far different world. At least they won’t have to worry about ice ages for some 100’s of thousands of years.

  5. indy222 Says:

    If societal breakdown ensues in a serious way, which I think is quite possible, the food riots and infrastructure so necessary for life in the 21st century may suffer too much to support a billion. The Laissez Faire Libertarian First Law of Existence “Each individual pursuing his own selfish interest also best guarantees the well-being of Society as a whole”, will be revealed for the fallacy it is, in a very harsh way. The 1% may be OK for a while, in their gated and machine-gun guard towered enclaves – I suppose we can be grateful for that.

    • dumboldguy Says:

      Yeah, I was trying to be optimistic when I said “at most” a billion. Didn’t want to get all the faint hearts atwitter, although the thought of what a drop from 7 billion+ to “at most” a billion should make them quite nervous.

      I have seen other estimates of a sustainable population of about 500 million and even less on up to 2+ billion. (And with any luck, many of the 1% will get theirs from the 99% when the “harshness” begins).

  6. […] “Nobody expected that it could do something so bizarre”: Global warming could push bacte… (Climate Crocks) [emphasis added]: A new study from USC and the Massachusetts-based Woods Hole Oceanographic Institution (WHOI) shows that changing conditions due to climate change could send Tricho into overdrive with no way to stop – reproducing faster and generating lots more nitrogen. Without the ability to slow down, however, Tricho has the potential to gobble up all its available resources, which could trigger die-offs of the microorganism and the higher organisms that depend on it. […]

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