ALL ABOARD! BEHIND THE SCENES OF A SCIENTIFIC RESEARCH CRUISE

From our climate to the air we breathe, the ocean influences the world around us. Scientists are always looking for new ways to explore and study the ocean. One way we do this is by going on specially designed ships that allow us to study the deep sea, far from land. On our latest expedition aboard the Research Vessel Sally Ride, we went out 300 miles into the North Pacific Ocean for a week. We used some of the most important ocean science tools to catch tiny marine animals, collect water from some of the deepest depths, uncover mysteries of oceans past, and study how desert dust feeds marine animals today.

of the gasses that cause climate change [ ]. Fish from the ocean feed billions of people every day [ ].We rely on the ocean for so much that it is important to understand how it works and how humans are changing it.Scientists have lots of tools for studying the ocean.We can use satellites to look at the ocean from space, and we can study the ocean from the coast.These methods give us a good idea about the ocean's edges, but we also need ways to study the deep ocean, far away from land.To do so, scientists go to sea on specially designed ships with science tools for collecting all kinds of information.These research expeditions can be days or even months long.
Come aboard our expedition!Here is a look into our voyage on board the Research Vessel Sally Ride in the North Pacific Ocean.You can learn what we did at sea and how we used four important tools to study the ocean: the CTD, the multicorer, the tow, and aerosol samplers AEROSOL Small liquid or gas particles suspended in a gas.Here, this gas is air.(Figure ).

THE CTD: DIVING INTO THE DEEP OCEAN
The CTD is named after three things it measures."C" is for conductivity CONDUCTIVITY How easy it is for electricity to pass through a material.In the ocean, we use conductivity to measure how salty seawater is.
(how salty seawater is), "T" is for temperature (how hot or cold seawater is), and "D" is for depth (how deep the CTD has sunk).A CTD is shaped like a giant can with lots of smaller tubes inside it.It carries water samplers and electronic sensors [ ].We lower the CTD o the side of the ship, and as it sinks, it collects both samples and information (Figure A).We can also add more tools to the CTD to measure things like how much sunlight there is, how many living things there are, and Light et al.
how cloudy the water is.All this information is sent back up to the ship for the scientists to use.A,B).
We use information from the CTD to answer important questions about what happens in the ocean.On our cruise, Linqing used water from the CTD to explore how ocean water moves around.Tricia used the CTD to look at how food is recycled in the ocean (Figure C).Kaycie used the CTD to study how microbes, or tiny organisms, get

MICROBES
Living things that are too small to see with just your eyes.
energy from the food they eat.We sent the CTD down more than , m ( , feet) below the ocean's surface.

CORING: COLLECTING DEEP OCEAN MUD
We have a time machine aboard.the sea by rivers, dust, pollen, and ash blown from land, and dead organisms that sink from the sea surface.All this stu settles on the ocean bottom every hour of every day.As the centuries pass, the layers of mud thicken, preserving the history of fires, floods, and land life swept into the sea.The mud obtained by the multicorer tells the story of Earth's past.
How does the multicorer work?It looks like a moon lander with four legs supporting a triangular structure attached to the ship with a cable.Heavy weights slowly shove eight plastic tubes into the seabed.The device is then hauled back to the ship with a cable.Each tube is sealed by spring-loaded doors to preserve the mud inside.The tubes of mud are called cores.
The layers in the cores capture information about how humans are changing the world.Looking back at what Earth was like long ago helps us predict how the Earth might change in the future.On our cruise, Cate is using cores to find out how much of the plastic that humans throw away ends up on the seafloor.She will compare the mud now to mud from decades ago, to see how it has changed.The cores are like a fat book of Earth's history-a time machine to our past.

TOWS: CATCHING LITTLE ANIMALS IN OUR NET
We do not care only about ocean mud and ocean water-we also care about ocean life!We use a net tow (Figure D) to catch zooplankton, ZOOPLANKTON A category of ocean animals that mostly drift along with ocean currents.Zooplankton include everything from big jellyfish to tiny larvae.which are small ocean animals that mostly drift along with ocean kids.frontiersin.orgLight et al.
currents [ ].Most zooplankton are so tiny that you need a microscope to see them well (Figure D).Some zooplankton, like jellyfish, are bigger.Zooplankton are an important part of the ocean's food web because they get eaten by fish and other animals.Lots of large animals like tuna, squid, and crabs start out as plankton before they get big, while others remain tiny their whole lives.
The tow looks like a net that you might use to catch fish in a stream, but ours is so big that it takes a full team of scientists to use.Its holes are much smaller than a fishing net's holes, so zooplankton will not float through.We hang the tow o the side of the ship into the water.We then move the boat forward, so the tow catches the zooplankton swimming through the water.After a few minutes, we bring the net back to the ship to see what we caught.We have a microscope on the ship to see what the tiny zooplankton look like.We also store some of the zooplankton to study back on land.
We collect zooplankton to answer all sorts of questions: How do plankton change over time?Are large or small plankton more common?What do plankton eat and where does it come from?On our cruise, Annie collected zooplankton to help answer some of these questions.Some of the zooplankton also end up in the Scripps' Collections, where they will sit on shelves like library books alongside samples over years old!

AEROSOL SAMPLING: COLLECTING DUST FROM OCEAN AIR
Did you know that plankton get food from the sky?Although you might not be able to see it, there are billions of tiny pieces of rock floating around in the air all around you [ ].These little particles are called dust.Around million tons of dust fall into the ocean each year, bringing with it nutrients like iron that many organisms, like phytoplankton, PHYTOPLANKTON Microscopic organisms that live in water and get their energy from the sun, just like plants do on land.need to live.This dust comes from all over the world, including the Sahara Desert in Africa and glaciers in Alaska.It floats with the wind until it eventually falls into the ocean, where it can be used by animals.The amount of dust that enters the ocean changes depending on what is happening on land.Dust helps determine how much life is in the ocean, which can a ect global climate by adding or removing gasses from our atmosphere.

ATMOSPHERE
The layer of gases that surround our planet.
Onboard the ship, Emmet studied dust by sucking lots of air through a filter that catches the dust.To do this, he used a type of aerosol sampler called a Hi-Vol air sampler.Back on land in his lab, he can learn a lot about this dust.He hopes to learn more about the amazing ways that air transports nutrients around the world, even if we cannot see it with our eyes.
Light et al.

HOW CAN I GO TO SEA?
There are all sorts of ways to become a scientist who goes to sea.The scientists on our cruise are from five di erent countries.They studied various college subjects-chemistry, biology, physics, anthropology, and even art!Some of them have always wanted to study the ocean, and some did other things before becoming ocean scientists.We all worked really hard and prepared a lot so that we could deal with the challenges of being at sea.Some of the problems we overcame during our cruise were people getting sick, tools breaking, and experiments not working the way we expected.To get a taste of what it is like to be a scientist at sea, explore websites (like this one) about ocean science.You can also get out and explore near where you live, from a park to a stream to a city block.To become a scientist, you need a sense of wonder and you must pay attention to little details, write everything down, and notice changes that happen over time.Above all, have fun!Light et al.

NATALIA G. ERAZO
Natalia Erazo is a marine microbiologist and Ph.D. candidate at the Scripps Institution of Oceanography in San Diego, California.Natalia studies how microbes are responding to climate change and pollution.She is interested in conservation policy, climate change adaptation and mitigation, and works with women-led fisheries on seafood sustainability and how to better protect marine ecosystems.She loves swimming, diving, and sailing.

RICHARD NORRIS
Richard Norris is a paleontologist at the Scripps Institution of Oceanography in San Diego, California.He is interested in the impact of past environmental change on ocean life.Lately he has been using microscopic fish teeth and bones to understand how the abundance of reef fish keeps corals healthy.The tiny fossils he extracts ocean mud tell lots of neat stories about how people have changed the world.He enjoys traveling the deserts, looking at birds, and making jam and a warm scone!

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FigureThis illustration of our ship at sea shows various parts of the ocean and how we use our equipment to study them.It shows a net tow dragging through the water, a multicorer collecting marine sediment (or mud), a CTD collecting seawater, and a Hi-Vol air sampler collecting aerosols at the front of the ship.The ship is about m ( feet) long.Take a virtual tour of the ship here, and visit this site to learn more about our day-to-day activities on the ship.

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Figure Science at sea. (A) Scientists prepare the CTD to collect seawater.(B) Kaycie leads a team collecting microbes from seawater.(C) Cate uses a multicorer to collect deep sea mud.(D) Annie sends out the net tow to sample plankton.