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.
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?
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.
For the rest of the story, visit Every Other Breath.