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
Dennis Allen sampling near the North Inlet.
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?
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
Photo by Wade Spees
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