Human CO2 Emissions to Drive Key Ocean Bacteria Haywire, Generate Dead Zones, Wreck Nitrogen Web

Trichodesmium. It’s the bacteria that’s solely responsible for the fixation of nearly 50 percent of nitrogen in the world’s oceans. A very important role for this microscopic critter. For without nitrogen fixation — or the process by which environmental nitrogen is converted to forms usable by organisms — most of life on Earth would not exist.

Now, a new study produced by USC and the Massachusetts-based Woods Hole Oceanographic Institution (WHOI), has found that human carbon emissions are set to drive this essential organism haywire. Forcing evolutionary changes in which the bacteria is unable to regulate its growth. Thus generating population explosions and die-offs that will be very disruptive to the fragile web of life in the world’s oceans.


(A Trichodesmium bloom off New Caledonia. Image source: Earth Observatory.)

Trichodesmium — A Mostly Helpful Bacteria Essential to Ocean Life

Trichodesmium is a form of cyanobacteria. It resides in the near surface zone composing the top 200 meters of the water column. Possessing gas vacuoles, the bacteria is able to float and sink through the water column in order to access the nutrients it needs for growth — nitrogen, iron, and phosphorus. A widespread bacteria, it is often found in warm (20 to 34 C), nutrient-poor waters in the Red Sea, the Indian Ocean, the North and South Atlantic, the Caribbean, near Australia, and in the Northeastern Pacific.

Trichodesmium congregates in blooms which are generally a straw-like color. For centuries, this coloration has generated its common name — sea straw. However, in higher concentrations it can turn waters red. The Red Sea, for example, owes its name to this prolific little bacteria. Trichodesmium blooms generate a strata that support mutualistic communities of sea creatures including bacteria, diatoms, dinoflagellates, protozoa, and copepods. These small organisms, in turn, are fed on by a variety of fish — notably herring and sardines.

But Trichodesmium’s chief role in supporting ocean health is through making nitrogen in the air and water available to living organisms. It does this by turning environmental nitrogen into ammonia as part of its cellular metabolism. This ammonia can then be used for growth by a wide variety of creatures on up the food chain. Trichodesmium is an amazing producer of this biologically available nitrogen — perhaps generating as much as 50 percent of organic nitrogen in the world’s oceans (70 to 80 million metric tons) each year.

Human Fossil Fuel Burning is Projected to Drive Trichodesmium Haywire

But now a new study by USC and WHOI shows that atmospheric CO2 concentrations projected to be reached by the end of the 21st Century in the range of 750 ppm CO2 could force Trichodesmium’s nitrogen fixation rate into overdrive and lock it there indefinitely.

Trichodesium Nitrogen Fixation before and after

(Rate of nitrogen fixation in Trichodesmium at 380 ppm CO2 [black and red], at 750 ppm CO2 [pink, yellow and light blue], and when CO2 levels are returned to 380 ppm after five years of exposure to 750 ppm levels [dark blue]. Image source: Nature.)

The study subjected Trichodesmium to atmospheric CO2 concentrations (750 ppm) projected under a somewhat moderate rate of continued fossil fuel burning scenario by 2100 for five years. After this five year period of exposure, Trichodesmium nitrogen fixation rates nearly doubled (see above graphic). But, even worse, after the Trichodesmium bacteria were returned to the more normal ocean and atmospheric conditions under 380 ppm CO2, the rate of nitrogen fixation remained elevated.

In essence, researchers found that Trichodesmium evolved to fix nitrogen more rapidly under higher ocean acidity and atmospheric CO2 states at 750 ppm levels. But when atmospheric levels returned to 380 ppm and when oceans became less acidic, Trichodesmium’s rate of nitrogen fixation remained locked in high gear. For an organism like Trichodesmium to get stuck in a broken rate of higher metabolism and growth is practically unheard of in evolutionary biology. Organisms typically evolve as a response to environmental stresses. Once those triggers are removed, organisms will typically revert to a near match of previous states. Strangely, this was not the case with Trichodesmium.

David Hutchins, professor at the USC Dornsife College of Letters, Arts and Sciences and author of the new study described this alteration to Trichodesium as ‘unprecedented’ stating that:

“Losing the ability to regulate your growth rate is not a healthy thing. 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.”

Uncontrolled Blooms, Population Crashes, Biotoxin Production, Dead Zones

Nitrogen is a key component of cellar growth. So Trichodesmium nearly doubling its rate of nitrogen fixation means that the bacteria’s rate of production will greatly increase as atmospheric CO2 levels and ocean acidification continue to rise. Under heightened CO2, the bacteria essentially loses its ability to restrain its population.


(Large algae/bacterial blooms like this red tide off La Jolla, San Diego are causing the expansion of hypoxic and anoxic dead zones throughout the world’s oceans. A new study has found that one of the ocean’s key microbes goes into growth overdrive as atmospheric and ocean CO2 concentrations rise — which would greatly enhance an already dangerous rate of dead zone expansion in the world ocean system. Image source: Commons.)

As a result, researchers warn that Trichodesmium blooms may run out of control under heightening levels of CO2. Such out of control blooms would rapidly remove scarcer nutrients like phosphorous and iron from the water column. Once these resources are exhausted, Trichodesmium would begin to die off en-masse. As with other large scale bacterial die-offs in the ocean, the decaying dead cellular bodies of Trichodesmium would then rob the nearby waters of oxygen — greatly enhancing an already much amplified rate of anoxic dead zone formation. And we know that anoxic waters can rapidly become home to other, far more dangerous, forms of bacterial life. In addition, large concentrations of Trichodesmium are known to produce biotoxins deadly to copepods, fish, and oysters. Humans are also rarely impacted suffering from an often fatal toxicity response called clupeotoxism when the Trichodesmium produced toxins biomagnify in fish that humans eat. Sadly, more large Trichodesium blooms will enhance opportunities for clupeotoxism to appear in human beings.

Exacerbating this problem of heightened Trichodesmium blooms and potential related dead zone formation is the fact that ocean waters are expected to become more stratified as human-forced warming continues. As a result, more of the nutrients that Trichodesmium relies upon will be forced into a thinner layer near the surface — thus heightening the process of bloom, die-off, and dead zone formation.

Final impacts to ocean health come in the form of either widely available nitrogen, (during Trichodesmium bloom periods) which would tend to enhance the proliferation of other microbial life, or regions of nitrogen desertification (during Trichodesmium die-offs). It’s a kind of ocean nitrogen whip-lash that can be very harmful to the health of life in the seas. One that could easily ripple over to land life as well.

No Return to Normal

But perhaps the most shocking finding of the new research was that alterations in Trichodesmium’s rate of growth and nitrogen fixation may well be permanent after the stress of high CO2 and ocean acidification are removed. Hinting that impacts to ocean health from a rapid CO2 spike would be long-lasting and irreparable over anything but very long time-scales. Yet more evidence that the best thing to do is to avoid a major CO2 spike altogether by cutting human carbon emissions to zero as swiftly as possible.


Irreversibly Increased Nitrogen Fixation in Trichodesmium in Response to High CO2 Concentrations

Climate Change Will Irreversibly Force Key Ocean Bacteria into Overdrive


Earth Observatory

Red Tide Algae Bloom off San Diego

Awakening the Horrors of the Ancient Hothouse

Trichodesmium: A Widespread Marine Cyanobacteria with Unusual Nitrogen Fixation Properties

Nitrogen Fixation

Hat Tip to Colorado Bob

Shades of a Canfield Ocean — Hydrogen Sulfide in Oregon’s Purple Waves?

Are we already starting to awaken some of the horrors of the ancient hothouse ocean? Are dangerous, sea and land life killing, strains of primordial hydrogen sulfide producing bacteria starting to show up in the increasingly warm and oxygen-starved waters of the US West Coast? This week’s disturbing new reports of odd-smelling, purple-colored waves appearing along the Oregon coastline are a sign that it may be starting to happen.

Purple Waves

(Purple waves wash over the Oregon beach of Neskowin on August 15. A form of hydrogen sulfide consuming bacteria is known to color water purple. Is this an indicator that the deadly gas is present in Oregon’s waters? Image source: Jeanine Sbisa and Beach Connection.)

A Dangerous Beauty

Oregon beachgoers and ocean researchers alike are flummoxed. There’s something strange in the water. Something that’s coloring the waves of Oregon’s beaches purple even as the off-shore waters are painted greenish-blue. These puzzling purple waves have been washing up along the Oregon Coastline for the better part of a month. And no-one seems to know exactly what’s causing it.

Eyewitness photographer Jeanine Sbisa described the scene at Neskowin:

“The purple was only on the edge of the water. I did not see any patches in the deeper water. ( in fact the deeper water was a beautiful turquoise, instead of the deep blue that it usually is at Winema). Some of the waves were a deep clear purple. Other waves in other segments were a rich foamy lilac color. The colors were amazing. Very beautiful.”

All up and down Oregon’s coastline similar reports have been surfacing. Oregon State Park Ranger Dane Osis photo documented another incident at Fort Stevens State Park near Astoria. And eyewitnesses at some locations have described a ‘funky smell’ issuing from some of the purple-colored waters.

Initial reports have claimed that there’s no evidence the purple waters are harmful. But such assertions may well be premature.

Purple Sulfur Bacteria

At issue is the fact that the waters off Oregon are increasingly warm. They are increasingly low oxygen or even anoxic. Conditions that are prime for the production of some of the world’s nastiest ancient species of microbes. The rotten-eggs smelling hydrogen sulfide producing varieties. The variety that paint the waters green (or turquoise as described by Jeanine Sbisa above) or even an ugly black. And there is one primordial creature in particular that thrives in warm, low-oxygen, funky-smelling water. An organism that’s well known for coloring bodies of water purple — the purple sulfur bacteria.

Purple Canfield Ocean

(Artist’s rendering of what a Canfield Ocean may have looked like. A Canfield Ocean is a deadly hothouse ocean state implicated in 5 of 6 major mass extinction events. And, perhaps, we see a hint of this deadly ocean along the Oregon coast today. Image source: Biogeochemistry.)

In order for blooms of purple sulfur bacteria to form, waters have to be low in oxygen or anoxic. There has to be hydrogen sulfide gas present in the water. And the water has to be relatively warm. This is because the bacteria is warmth-loving, anaerobic, and it uses the sulfur in hydrogen sulfide gas as part of its energy production process.

In the current day, the purple sulfur bacteria is present in anoxic lakes and geothermal vents. But during ancient times and during times of hothouse extinction, the purple sulfur bacteria are thought to have thrived in the world’s oceans — painting them the strange tell-tale purple we see hints of along the Oregon shoreline today. A purple that was the hallmark color of a life-killing hothouse ocean.

In his ground-breaking book “Under a Green Sky,” Dr. Peter Ward vividly describes what a Canfield Ocean may have looked like:

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 colour – a vast, flat, oily purple, not looking at all like water, not looking 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 colour comes from vast concentrations of floating bacteria, for the oceans of Earth have all become covered with a hundred-foot-thick [30m] veneer of purple and green bacterial soup.

The purple sulfur reducing bacteria, though not dangerous themselves, live in a kind of conjoined relationship with the much more deadly hydrogen sulfide producing bacteria. The purple, is therefore, a tell-tale of the more deadly bacteria’s presence. And hydrogen sulfide producing bacteria may well be the most dangerous organism ever to have existed on the planet — largely responsible for almost all the great extinction events in Earth’s deep history. For hydrogen sulfide itself is directly toxic to both land and ocean-based life. Its deadly effects are increased at higher temperatures. And not only is it directly toxic in both water and air, if it enters the upper atmosphere it also destroys the ozone layer.

(Video shot on July 18 [please excuse the colorful language] showing purple waters and dead jellies, barnacles and mussels on another Pacific Ocean beach. Video source: Gezzart.)

Purple waters are a sign that the little organisms that produce this deadly agent may be starting to bloom in an ocean whose health is increasingly ailing. Tiny tell-tales that we’re on a path toward a hothouse Canfield Ocean state. A path we really don’t want to continue along through the ongoing burning of fossil fuels. For that way leads toward another great dying.

*  *  *  *  *

Pigmented Salps — An Indicator of Bio-Magnification?

UPDATE TUESDAY, SEPTEMBER 1: According to reports from Oregon’s Department of Fish and Wildlife, Oregon’s purple waves are being caused by the large-scale spawning of an oxygen dependent jellyfish-like vertebrate called a salp in the near shore zones along the Oregon coastline. The normally clear salps have apparently developed a purple pigmentation which is coloring the waves in this region a strange hew. The findings, though seemingly reassuring, raise more questions than they do answers.

First, salps do not typically spawn in the near-shore region. However, during recent years, near shore salp spawnings have become more common leading to reports of these jellies washing up all along the U.S. Coastline. Phytoplankton and other bacteria are a typical food source for salps and the jellies are mobile enough to follow this food. So large blooms in the near shore ocean could be one reason for salps coming closer to shore.

Second, salps are typically clear — devoid of any pigmentation. So the question here is how are salps picking up this strange purple color? Since salps are filter-feeders known to eat bacteria, it’s possible that a highly pigmented food source or a source laden with purple sulfur bacteria may be resulting in this odd new coloration for salps. So identifying pigmented salps as the source of the purple coloration does not necessarily eliminate the possibility of sulfur reducing bacteria being present in either the near shore or the off shore waters where salps typically reside and feed. Pigmentation, in this case, may be due to salps bio-magnifying the natural pigmentation in their food source. Given the fact that salp coloration is practically unheard of, it’s somewhat puzzling that marine researchers haven’t investigated this particular mystery a bit further.

Third, the region off the Oregon coastline has been increasingly low in oxygen due to a combination of eutriphication, ocean current change, and ocean warming. This fact of declining ocean health in the off-shore Oregon environment is contrary to assertions circulated in some media sources claiming that large salp blooms are a proof that the environment in the bloom region is healthy. Salp blooms follow bacterial and phytoplankton blooms. And such blooms are well known triggers for dead zone formation. Though salps tend to aid in mitigating these blooms, their presence is not necessarily a sign of healthy waters. Conversely, in the case of very large algae blooms, salps presence may indicate just the opposite. Since salps are oxygen-dependent, it’s possible that the near shore environments where wave mixing tends to oxygenate the water is a drawing these vertebrate jellies closer in due to a loss of an off shore environment healthy enough to sustain them.

As with the freak appearance of pink pigmented salps at Manzanita during 2010, the widespread purple waves off Oregon during 2015 remain somewhat of a mystery. The key question as to why salps, that are known to be a clear-bodied species, are picking up a pigmentation very similar to that possessed by purple sulfur bacteria has not been answered.


Purple Waves Puzzle Oregon Coastal Scientists

Awakening the Horrors of the Ancient Hothouse — Hydrogen Sulfide in the World’s Warming Oceans

Purple Sulfur Bacteria

Canfield Ocean

Under a Green Sky


Hat Tip to Wharf Rat

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