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Meet the Ghostly Organisms that Rescue the Planet

Photo credit: Lars Plougmann from London, United Kingdom, CC BY-SA 2.0 , via Wikimedia Commons.

A man was paddleboarding last month when he came across a mysterious creature three miles off the shoreline of California. He was startled by the sight, and then filled with wonder. What was this “see-through floating spine” in front of his paddleboard? If it could talk, it might have said, “Fear not. I am here to rescue your world from global warming.” 

The story is told on Phys.org by Amanda Lee Myers. On the other side of the world, another man had a similar revelation. David Malmquist, writing for the Virginia Institute of Marine Science, tells about a swimmer who was snorkeling through waters off the coast of New Zealand when he found himself enveloped in a fog of translucent beings. If these angelic creatures could talk, they might have said, “We mean you no harm. We are your servants. Our work is to remove the gases with which your species has polluted the atmosphere and send them to the bottom of the sea.”

We should get to know these friendly servants. Who are they? What are they? They are called sea salps. They look a bit like jellyfish with their transparent bodies, but they are not jellyfish. Scientists classify them as tunicates: animals with see-through “shirts” of gelatin. Sea squirts are more familiar examples of tunicates. A tunicate is an odd kind of invertebrate because, though it looks like jellyfish, it has the key characteristic of phylum chordata: a notochord. A notochord is believed by evolutionists to be a precursor to a spinal cord, then a backbone. This gives Darwin-loving reporters the chance to amuse their readers with claims that sea salps are our “distant relatives” — closer to us than they are to jellyfish, which outwardly they more closely resemble. Phylogeny acquaints a species with strange bedfellows.

How Salps Sequester Carbon

The Virginia Institute of Marine Science reports on a study led by Dr. Deborah Steinberg of William and Mary. Her team found that “salps play [an] outsize role in damping global warming.” How? The salps, also called jelly plankton, are good at absorbing carbon dioxide and “pumping” it down to the ocean bottom. Their numbers, furthermore, can multiply into huge “blooms” when CO2 is plentiful.

Jelly plankton blooms can offset as much CO2 as emitted by millions of cars. Humans continue to amplify global warming by emitting billions of tons of carbon dioxide into the atmosphere each year. A new study reveals that a distant human relative plays an outsize role in damping the impacts of this greenhouse gas by pumping large amounts of carbon from the ocean surface to the deep sea, where it contributes nothing to current warming. [Emphasis added.]

A NASA-funded multidisciplinary project called EXPORTS is combining satellite data with shipboard measurements to understand a global phenomenon: the “biological pump.”

The goal of EXPORTS, for EXport Processes in the Ocean from RemoTe Sensing, is to combine shipboard and satellite observations to more accurately quantify the global impact of the “biological pump.” This is a suite of biological processes that transport carbon and other organic matter from sunlit surface waters to the deep sea, effectively removing carbon dioxide from the surface ocean and atmosphere. Tiny drifting animals called zooplankton play a key role in the pump by eating phytoplankton — which incorporate carbon from carbon dioxide into their tissues during photosynthesis — then exporting that carbon to depth.

These “jelly barrels” with their notochords are like “transparent whales,” Malmquist writes, taking in the carbon dioxide from their meals and pumping it down to the ocean floor in their fast-sinking fecal pellets. But wait, there’s more: the salps, like Salpa aspera, also take the stored carbon down in person. Sea salps take part in the “diel vertical migration” habit of many plankton: a daily ritual of swimming to the surface during the night to feed, then swimming to the depths during the day to avoid predators. Since these asexual organisms can multiply rapidly, the combined influence of their biological pumping can be huge. Do the math:

To put things in perspective, the observed salp bloom covered more than 4,000 square miles (~11,000 km2), about the size of Connecticut. With onboard experiments showing salps capable of exporting a daily average of 9 milligrams of carbon through each square meter at 100 meters below the bloom, the amount of carbon exported to the deep sea was about 100 metric tons per day. For comparison, a typical passenger car emits 4.6 metric tons per year. Comparing these values shows the carbon removed from the climate system each day of the bloom is equal to taking 7,500 cars off the road. Adjusting these values using the team’s highest measured rate of salp-mediated export (34 mg of C per day) increases the carbon offset to more than 28,000 vehicles.

There’s still more. Steinberg says that many salp blooms go undetected. A global model that estimates their effects leads to a startling conclusion: these tunicates transport a whopping “700 million metric tons of carbon to the deep sea each year, equal to emissions from more than 150 million cars.” Thank you, sea salps!

Steinberg’s research was published open access in Global Biogeochemical Cycles, a journal of the American Geophysical Union.

Global Biological Pump

Another study was published in Nature’s open-access journal Nature Communications by Decima et al., “Salp blooms drive strong increases in passive carbon export in the Southern Ocean.” A 14-member team from New Zealand and from Southern California’s Scripps Institute of Oceanography studied another salp species in the Southern Ocean, Salpa thompsoni. Like its cousin, this species takes part in the diel migration and drops its solidified carbon load in fast-sinking fecal pellets.

Zooplankton grazers, and their changing abundance and distribution patterns as a consequence of global warming, have the potential to not only alter marine food webs, but also biogeochemistry. If the increasing trend in salp abundance in the Southern Ocean persists at comparable rates, we can expect important changes in areas where salp blooms are recurrent: in the dynamics of phytoplankton bloom formation and termination, in the absorption and sequestration of carbon dioxide by the ocean, and in the composition of exported plankton affecting both organic and inorganic carbon flux to the deep ocean.

More Ways to Appreciate Jelly Plankton

Myers’s article at Phys.org includes “six wild facts about sea salps” to increase our appreciation of our global servants. Some of those have been mentioned above. The first two are newsworthy:

  • They move by pumping water through their bodies in what’s considered one of the most efficient examples of jet propulsion among animals, according to the Journal of Zoology.
  • Sea salps also eat using jet propulsion, consuming microscopic plants known as phytoplankton as they pump water through their bodies, the journal says.

They are also among the fastest-growing animals known, Myers continues, able to increase their body length by as much as 10 percent per hour. So while salps share jet propulsion finesse with jellyfish, they are more closely related to humans, evolutionists say. 

Now for Something Completely Different: A Geological Carbon Pump

Adding to salps’ outsized role in carbon sequestration, a non-biological process also participates in saving the planet. Brantley et al., writing in Science, relate “How temperature-dependent silicate weathering acts as Earth’s geological thermostat.” Silicate weathering “is an important way that carbon dioxide is regulated over geological time scales.” News from Penn State says that it must have been in operation throughout the history of life:

“Life has been on this planet for billions of years, so we know Earth’s temperature has remained consistent enough for there to be liquid water and to support life,” said Susan Brantley, Evan Pugh University Professor and Barnes Professor of Geosciences at Penn State. “The idea is that silicate rock weathering is this thermostat, but no one has ever really agreed on its temperature sensitivity.”

Measurements in the paper indicate that, indeed, chemical weathering responds to earth temperature automatically: hotter temperatures increase carbon sequestration by weathering, and lower temperatures reduce it. The paper says this explicitly:

Over multimillion-year time scales, the balance between weathering of silicate rocks and volcanic degassing may control the atmospheric concentration of CO2, one of the most important greenhouse gases that regulate Earth’s climate. Silicate weathering accelerates with temperature, acting as a negative feedback that buffers Earth’s climate and maintains its habitability.

The earth, therefore, seems to come with built-in regulators for climate and temperature. Are climate modelers who warn us of impending catastrophe incorporating these “poorly understood” processes into their dire predictions?

Evidence of Providence?

We have learned about another class of amazing little animals — sea salps — that many of us probably never heard of but depend on. These studies add to growing knowledge about the roles of plankton, including polychaetesdiatoms, and other small ocean creatures, whose benefits to the planet are as elegant as their well-engineered designs.

Are sea salps living only for their own fitness, or do we see evidence of providence here? Their outsized role gives the earth a biological feedback mechanism, somewhat like a thermostat, to regulate carbon emissions in the atmosphere. Maybe the planet needs biology as much as biology needs the planet. And to discover that biological and geological processes work together automatically to regulate greenhouse gases and keep global temperatures optimized for habitability seems uncanny. That would seem to require foresight and wisdom on a grander scale than Darwin’s theory can handle.