Every Other Breath
Plankton produce half of the oxygen on Earth and suck out massive amounts of carbon dioxide. But from South Carolina to the open ocean, scientists are seeing dramatic changes in these mysterious creatures. Life on Earth literally began with them, and they could very well determine the climate’s fate. Oh, and they’re beautiful.
Chapter 1: An urgent mystery
It’s early in World War II, and America’s fate is tied to the sea. In the Atlantic, Nazi U-boats pick off convoy ships, threatening the lifeline to Europe. In the Pacific, Japanese subs prowl the depths, testing a fleet battered at Pearl Harbor. Meanwhile, American war planners know little about this new underwater battlefield. Mastering its terrain could prove decisive. In a secret report, the leader of a hastily assembled group of scientists called Division 6 writes about an urgent need to understand the ocean “for service in a national emergency.”
New sonar instruments would be the tool. You could ping the ocean bed, then use the bounce to calculate the seafloor’s depth and shape. But sonar operators soon pick up something odd: The seabed seems to move up and down. More pings, and Navy technicians uncover a pattern: This “false bottom” rises at night and descends at dawn. What is it?
Must be alive, the Division 6 scientists think. Squids? Schools of fish? Has to be something pervasive; the sonar picks up false bottoms in all of the world’s oceans. Whatever it is, could American submarines hide under it? Could enemy subs?
Division 6 doesn’t answer these questions before the war’s end, which only stokes more curiosity. Scientists begin calling the false-bottom the “deep scattering layer.” They toss nets into the layer; they haul up a few squids and fish but not enough to explain those scattering pings. Then, with fine mesh nets and deep-sea diving gear, scientists in the 1970s finally solve the mystery: The false bottom is a massive daily migration of plankton.
This symphony of tiny and beautiful creatures begins at night when they rise to feed on even smaller surface plankton. Countless fish join this movement — so many that the ocean hums. Then it ends at sunrise as they plunge to escape predators. Though unseen, this daily cycle is the grandest migration of all on Earth. From an ecological standpoint, it’s exponentially more significant than the Serengeti’s thundering wildebeest or the winged journeys of the world’s birds. And it’s just a small part of the plankton story. Startling new discoveries about plankton could prove decisive in an emergency that’s as urgent as any war: a rapidly changing climate.
The question remains: Will we learn enough in time?
Chapter 2: The power of plankton
Plankton may be the most important stuff you’ve barely heard of — more important to the climate’s fate than rainforests. The term plankton is a catchall of sorts for living things that are at the mercy of currents. That broad definition includes jellyfish, krill, marine bacteria, viruses, algae and fish larvae. With no roots to the seabed, planktonic creatures mostly drift, though as those World War II pings revealed, some are masters at swimming up and down. Many forms of plankton are so tiny you need a microscope to see them, but they are the unsung heroes of the planet’s air.
You can thank species of sun-loving plankton for the breath you just took. Until about 2 billion years ago, the planet’s atmosphere was breathlessly devoid of oxygen. But then a distant cousin of today’s blue-green algae began using the sun’s rays to split water into hydrogen and oxygen. Earth hasn’t been the same since.
Today, half of the atmosphere’s oxygen comes from ocean plankton — every other breath. Plankton comes in all shapes and sizes, but scientists divide them into two categories.
Phytoplankton are the microscopic algae and other cells that drift in the sun-infused upper layer of the ocean. Think of them as the plants of the sea, the oxygen producers. Zooplankton are the larger animals that typically feed on the phytoplankton. Think of them of the sea’s insects, snails and worms.
Small and large, plant and animal, they do amazing things.
One zooplankton called phronima chomps on smaller plankton and uses their body parts to make protective cellulose barrels. The mother lives in the barrel, zealously guarding her young, while males bolt at the slightest danger. Phronima’s fierce appearance is the inspiration for the creature in the movie “Alien.”
Some algae and bacteria have red pigments and grow so dense they color vast areas of the ocean; floating pink blankets of bacteria gave the Red Sea its name. One zooplankton species has little blue sails; washing up on the beach, their colonies look like a regatta of tiny blue boats. Another jellyfish can literally reverse its aging process; its nickname is “the immortal jellyfish.”
When phytoplankton die, they emit cloud-forming chemicals that give beaches their intoxicating and briny smell. Some phytoplankton also are killers: Shaped like glistening needles, they secrete neurotoxins that find their way into shellfish and animals that feed on them. After one toxic algal bloom in 1961 in Monterey Bay, Calif., thousands of poisoned seabirds dive-bombed houses and cars and piled up dead on streets. The phenomenon inspired Alfred Hitchcock’s movie, “The Birds.”
Counting plankton is like counting stars, though instead of stars, some species look like Christmas ornaments and the Leaning Tower of Pisa. A single teaspoon of seawater might contain a million phytoplankton bacteria and 100 million planktonic viruses that feed on them. Viruses alone have an overall biomass in the oceans of 75 million blue whales. Mostly unseen, these hordes of planktonic algae and viruses are in a constant state of biochemical warfare: The viruses attack the algae while the algae develop special plates of armor.
Much of what we know about plankton has been discovered since World War II, thanks in part to those curious Division 6 scientists, but also because of people like Dennis Allen, who one morning in January, stands in a johnboat in a South Carolina marsh, wondering: Why does the water look so weird?
Curiosity, and the Long View
Dennis Allen is resident director of the University of South Carolina’s Belle W. Baruch Marine Field Laboratory, a science center deep in an area of protected pinelands and marsh north of Georgetown. He has a boat captain’s white beard and his brown eyes hold a look of delight. He has long been fascinated by the hidden underwater world, and it’s easy to imagine that delighted look 60 years before when he watched those Amazing Live Sea Monkeys hatch. (The old comic book ads said: “Own a bowl full of happiness! Because they are so full of tricks, you’ll never tire of watching them.”) Those brown bits didn’t really look like monkeys, though. And he would learn much later that biologists called them brine or fairy shrimp. But they spun and darted and moved about nevertheless, a small world of their own that hinted at a much larger one if you just look closer.
Which he did often with Pop-Pop, his grandfather. An Italian immigrant and successful auto dealer, Pop-Pop took him fishing off the New Jersey coast. His grandfather seemed to be curious about everything in the water, which was infectious to an already curious child.
“Pop-Pop, why do we catch flounder here but not over there?” he asked his grandfather.
“That’s a good question!”
“Pop-Pop, what do the fish eat?”
Gutting the fish, they found dead shrimplike animals in the stomachs — not so different than those Amazing Live Sea Monkeys.
Fast forward to the mid-1970s. Allen was a biologist by now, working on his dissertation, trawling with a fine mesh net off New Jersey, funneling zooplankton into a jar at the end of the net. He pulled up the net and looked at the jar. It was full of mysids, those shrimp-like animals he saw when gutting fish with his grandfather. From a distance, the jar looked as if packed with wild rice. But looking closer, you could see it teemed with life. New questions formed in his mind as he watched the mysids flit back and forth: What is their response to light? How do they move with the currents? Years later, he still keeps the jar on a shelf his office at the Baruch Institute. He smiles. “It’s a reminder of my roots.”
A reminder of the sense of discovery that fueled his most important work.
In January 1981, not long after he landed a job at Baruch, he collected samples in the salt marsh creeks of North Inlet. He recorded the water’s temperature, salinity and other chemical characteristics. He collected the zooplankton with a fine mesh net.
Then he kept at it, sampling every two weeks, using the same nets and protocols.
And he kept going, even when the funding was barely there.
As the decades passed, shelves filled with glass jars of the samples, preserved in a pink fluid; data filled columns and charts. Like a savings account, it slowly grew in value.
Today, this data is called a “time series,” and Baruch’s is the longest continuous time series in an estuary in North and South America, and perhaps the world.
Its rarity and scientific value can’t be overstated. With so much data collected consistently over such a long period, scientists can begin to understand how estuaries and salt marshes change over time.
And on the johnboat in January, he’s shocked by what he sees.
Chapter 4: The Zooplankton crash
It’s the 866th collection in the time series, the first of 2016. The marsh is a winter palate of pale yellows and greens. A bald eagle watches from the top branch of a dead tree. The jon boat moves into the current. The water is brown, the color of ice tea, and this is news.
“This time of year, it’s supposed to be grayish-green and really clear,” Allen says, as Paul Kenny steers the boat. Kenny, a research specialist, has been collecting samples with Allen for 33 years.
The source of the unusual color is last fall’s torrential rains. A record 2 feet fell in one weekend. It’s the kind of rain bomb scientists think we’ll see more of as the planet warms and the air holds more moisture. More rain fell in November, fueled by one of the largest El Niño’s in recent history. This morning, salt marshes have the salinity of freshwater ponds.
Strange weather, but Allen’s time series has revealed other surprises that go far beyond any blips in the jet streams.
He grabs a net that looks like a windsock and tosses it overboard. The net funnels zooplankton into a jar. He and Kelly pull in the trawl, and Allen lifts the jar to the sky. A translucent eel larva flickers amid the debris. It probably migrated from the deep ocean, perhaps from the Sargasso Sea.
“The big story is that there are a lot fewer zooplankton in North Inlet than there used to be,” Allen says.
When he began in 1981, a trash-can-sized amount of water held 10,000 to 12,000 zooplankton specimens.
Over time, the numbers declined. In recent years, they’ve been catching about 6,000 to 8,000.
“That’s a 40-percent reduction,” he says. “That’s huge, and it’s remarkable because it happened in just the course of 30 years.”
Rising temperatures might be responsible.
Human activity releases the equivalent of 36 billion tons of carbon dioxide into the air every year. This CO2 and other greenhouse gases trap heat in the atmosphere. The ocean, however, absorbs much of this warmth. Every day, humans and their machines add heat to the ocean equivalent to 345,000 Hiroshima-size atomic bombs.
This injection of heat has caused the ocean’s temperature to rise. Arctic and Antarctic ice are melting. And all these changes affect the mostly hidden world of plankton, the foundation of the food web.
Allen says they once caught hundreds of anchovies in trawls like today’s. But in recent years, they’ve caught one or two per tow, or none at all. Researchers in the Chesapeake Bay, the West Coast, New England and Europe are discovering similar reductions in zooplankton and fish species, he adds. Results of these time series findings will be published soon in scientific journals, but they only raise more questions.
What else is happening to the plankton?
Will this affect the climate?
And the air we breathe?
Chapter 5: Open ocean’s secrets
Across the Sargasso Sea near Bermuda, three young scientists on the boat Rumline prepare a gray canister that looks like a small torpedo. The boat slows. White foam breaks over a nearby coral reef. A Brazilian technician lowers the canister into gentle waves of turquoise. He hoists the canister back on board, and the three scientists take turns piping the contents into beakers. They repeat this four times at other spots off the island, then give a thumbs up to the captain, who turns the boat, painting a white arc of bubbles in the blue.
They head back to the island, with its white roofs like bleached coral, and dock at the Bermuda Institute of Ocean Sciences. In a lab there, they’ll take those beakers of seawater and measure salinity, pH and other aspects of the water’s chemistry. It’s work similar to Dennis Allen’s time series in South Carolina. But instead of estuaries, the Bermuda scientists focus on changes in the open ocean. As far as time series go, Bermuda’s is the longest-running in an ocean setting, and, therefore, among the most important.
Bermuda time series explained
“I’m from Ohio,” says Amy Maas, an assistant scientist here whose words tumble out in excitable bursts, “so people always ask, ‘Why should I care about what’s going on in the open ocean?’” Her eyes open wide, and her hands dart like fish. “And I say, ‘It’s all connected! Our water! Our air! And this place is one of the key places in the world where we’ve learned about the importance of marine bacteria, how migrating plankton change things, how the carbon cycle works.”
Growing up in Ohio, Maas thought she would be a librarian. But the more she learned about marine biology in college, the more she found herself captivated by its complexity and beauty. Drifting like plankton from course to course, and then in expeditions to Antarctica and the North Pacific, she found herself steered toward studies about climate change and a zooplankton group called sea butterflies, also known as pteropods. Now, she works in Bermuda with her husband, Leo, a Spanish zooplankton researcher, often bringing their new baby, Bastian, who sleeps in a crib next to her desk.
On an afternoon last February, a storm lashes the island, turning the cobalt waters below her office window into froth. Winds whip around the building, generating a sound like Tarzan’s jungle yell. Maas’ voice rises and falls as she recalls scuba diving with creatures from the deep scattering layer, the humming migration of plankton and fish that baffled the World War II sonar operators.
“During the day, you might see a fish here and there. But at night, when everything rises to the surface, boom, everything is there! The water is packed full of stuff. Wow. It’s extremely dark, and you can’t see anything beyond your big light. It looks like confetti, but it’s all moving around. It’s vibrant. You have these flashes of color. Everyone’s trying to eat and mate and do everything that needs to happen. It feels as intense as a coral reef or a rainforest. But everything is tiny! There are these little things zooming past. Zoom, zoom, zoom, and then a squid comes flying in! And then when you turn the lights off, there’s all this luminescence. And afterward you realize there’s so much that you don’t know.”
Such as the health of this ecosystem. It’s not easy to assess the status of the ocean’s microscopic creatures, she says. “You can’t ask a zooplankton, ‘Hey, how are you doing?’ That’s where the time series is vital. Time series aren’t flashy. They’re expensive; they’re time-consuming, and they’re not going to give you this big paper that says, ‘I just discovered X!’ They’re just a slow accrual of data.”
But with that growing collection of information, you can understand what happened in the past. Do it long enough, and you can factor out seasonal fluctuations. Then, she says, “you can use this information to make predictions about the future.”
Which, when it comes to the open ocean and its plankton, requires a deep breath.
Chapter 6: Uh-oh
It’s helpful to know a bit more about phytoplankton, the forests of the sea. Coccolithophores and diatoms are important sun-loving forms of phytoplankton. You can see blooms of coccolithophores from space, milky swirls as large as California.
Under a microscope, you’ll see they make fantastic shells. Shaped like flying saucers, they’re made of calcium carbonate, the same thing as chalk. The White Cliffs of Dover are old deposits of coccolithophores.
Diatoms, meantime, build glass shells that look like fancy hat boxes. Their shells are even smaller, so small that 30 can fit across a human hair. Medical examiners use diatoms in drowning cases: As victims inhale water, diatoms enter the bloodstream and make their way as far as the kidney and brain. If you find diatoms there, you know the person drowned instead of dying before entering the water. Diatom shells also are used in toothpaste, cat litter, dynamite and nail polish.
Diatoms and coccolithophores don’t just make useful and beautiful shells. They also incorporate huge amounts of carbon dioxide into their bodies. Then, larger zooplankton, such as Amy Maas sea butterflies, gobble them up. Or they die of old age, which in plankton time might be just a few weeks. Then, weighed down by their elegant shells, they fall toward the ocean floor, joining a chorus of other particles, including carbon-infused feces of zooplankton. Scientists call this falling stuff marine snow.
Marine snow piles up unseen on the ocean floor. And over millions of years, geological and other forces compress it and turn it into oil. This ongoing plankton bloom-and-bust represents a massive carbon pump to the ocean floor that scientists have only begun to fully understand. Every year, according to recent studies, phytoplankton incorporate 50 billion tons of carbon into their cells. That’s roughly the same as all the forests, bushes and grasses combined.
The Bermuda time series and other research have shown major changes in this biochemical balance. We’ve unlocked vast amounts of carbon dioxide by burning coal, gas and oil — carbon dioxide that took millions of years to sequester.
This has made the ocean more acidic — about 30 percent more acidic since the Industrial Revolution. This increase is faster than any known change in the sea’s chemistry in the past 50 million years.
And that’s bad news for some plankton.
Amy Maas’ research on sea butterflies has shown that even slight increases in acidity turn their shells from clear to opaque. Longer exposure, and the shells dissolve. Corals experience similar fates. Some researchers predict that because of ocean acidification, most of the world’s coral reefs could be dead within half a century.
To the surprise of scientists, coccolithophores, the chalk-making phytoplankton, are blooming at unprecedented rates in the North Atlantic — a ten-fold increase between 1965 and 2010. It’s unclear whether this is good news or bad. On the bright side, such blooms are sucking up some of the carbon dioxide we release when we step on the gas pedal. On the other hand, it’s a telling sign that we’ve pumped so much carbon dioxide into the air that our atmosphere and oceans are saturated. “Something strange is happening here, and it’s happening much more quickly than we thought it should,” one of the study’s authors wrote.
Finally, we have the warming ocean, which could affect plankton in an indirect but deadly way. Many species do just fine in the sea’s naturally changing temperatures. But they also depend on hidden underwater currents to stir up nutrients from cooler lower depths. This upwelling of nutrients is the equivalent of marine compost. But hot air hovering above the ocean creates a thick layer of warm water on the surface. And this turns that layer into a cap, preventing the upward movement of nutrients; with no mixing, phytoplankton starve.
You can outrun rising sea levels but with less oxygen, you won’t run far. Some scientists predict that because of global warming the ocean’s temperature may rise 11 degrees in the next 75 years. Under that scenario, many of the ocean’s mixing currents may disappear, researchers at the University of Leicester in England reported last December. With less oxygen from the ocean’s phytoplankton, the study’s authors said, the planet will experience “mass mortality of animals and humans.”
“Are we screwed?” People ask me that a lot,” Amy Maas says as the storm outside lets up. But she’s an optimist; humanity has a choice about reducing carbon dioxide emissions, reducing the size of that heat-trapping cap. “We’re intelligent organisms that can come together and make good decisions.” In other words, we’re not drifting like the plankton, subject to some external current.
Chapter 7: The new abnormal
In South Carolina, Dennis Allen and Paul Kenny continue their trawls. They point their boat toward a place with hidden sandbars and oyster reefs called No Man’s Friend. After nearly 40 years working these waters, Allen has answers to many questions he posed to his grandfather so long ago. But as will happen, this knowledge only triggered more questions.
The ocean hides its secrets well: the up-and-down movements of zooplankton that create the deep scattering layer; the movements of fish from the estuaries to the open ocean where they spawn; then the huge unseen migration of planktonic fish larvae back to the estuaries, where they grow into snapper, croaker and shrimp.
“Remarkable creatures,” he says. “I’ve been doing this for 38 years and I still get excited by what the net brings up.”
Which happens today. During a trawl, they find a catfish in their net.
A catfish in a salt marsh?
A surprise, but should it be?
Consider last fall’s rain bombs; winter’s record warm spell when people from Charleston to New York ran shirtless after Christmas; and the stunned scientists who recorded temperatures at the North Pole above freezing. “I just returned from a conference in Portland,” Allen says, mentioning a moderator who summed up the meeting’s findings: “He says, ‘Some wacky things are going on in our estuaries.’”
Ecology is all about relationships and understanding connections, he continues. Pull one string of the food web, and another part might unravel. Pull lots of strings, and sometimes those strings get tangled in a wad, which happens today.
During their first trawl of the previous year, they didn’t catch a single fish. Which is normal. Many fish are supposed to be in the open ocean now, spawning, laying eggs that will grow into planktonic larvae, the future tide-riders to the Carolina marshes.
But this year, their johnboat slows ever so slightly as the net behind it fills. They pull up the net, Allen straining, four decades of sampling taking its toll on his back.
The net is loaded with fish. Not just one school, either. Many schools of different fish.
“This is an event,” Kenny says, his voice suddenly firm. The fish aren’t supposed to be here now, and certainly not in these numbers. “This has never happened before at any time of year — winter, spring and fall.” Not in 35 years.
Must be the warmth of the waters, the change in the salinity, many factors probably hemmed them into the coast, he says. What will this do to the plankton? The food web? The climate? Tough to say exactly.
Other than it’s not supposed to be like this. Wacky.