Packing for a Journey into the Twilight Zone

Submitted for your consideration: A team of researchers from
more than 20 institutions, boarding two research vessels, heading into the ocean’s
twilight zone.

The twilight zone is a dimly lit region between 650 and 3300
feet below the surface, where we’re unfolding the mystery of how tiny ocean
organisms affect our planet’s climate.

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These tiny organisms – called phytoplankton – are plant-like
and mostly single-celled. They live in water, taking in carbon dioxide and
releasing oxygen.

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Two boats, more than 100 researchers from more than 20
partner institutions, and a whole fleet of robotic explorers make up the EXport
Processes in the Ocean from RemoTe Sensing (EXPORTS)
team. We’re learning more
about what happens to carbon dioxide after phytoplankton digest it.

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The Equipment to Find
Phytoplankton

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Phytoplankton have predators in the ocean called
zooplankton. They absorb the phytoplankton’s carbon, carrying it up the food
chain. The EXPORTS mission will focus partly on how that happens in the ocean’s
twilight zone, where some zooplankton live.  When phytoplankton die, sometimes their bodies
sink through the same area. All of this carries carbon dioxide into the ocean’s
depths and out of Earth’s atmosphere.

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Counting Life

Studying the diversity of these organisms is important to
better understand what’s happening to the phytoplankton as they die.
Researchers from the Virginia Institute of Marine Science are using a very fine
mesh net to sample water at various depths throughout the ocean to count
various plankton populations.

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Researchers from the University of Rhode Island are bringing
the tools to sequence the DNA of phytoplankton and zooplankton to help count
these organism populations, getting a closer look at what lives below the
ocean’s surface.

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Science at 500 Feet

Taking measurements at various depths is important, because
phytoplankton, like plants, use sunlight to digest carbon dioxide. That means that
phytoplankton at different levels in the ocean absorb and digest carbon
differently. We’re bringing a Wirewalker, an instrument that glides up and down
along a vertical wire to take in water samples all along its 500-foot long
tether.

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This journey to the twilight zone will take about thirty
days, but we’ll be sending back dispatches from the ships. Follow along as we
dive into ocean diversity on our Earth Expeditions blog: https://blogs.nasa.gov/earthexpeditions.

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