Author: sreiny

by Kris Gomes and Travis Mellett / NORTHEASTERN PACIFIC OCEAN /

The focus of our team is on a group of phytoplankton called diatoms, which are the floating, single-celled plants of the ocean. These organisms, through photosynthesis, use the energy from sunlight and the carbon dioxide we exhale and other sources to create food. Thus, they act as the base of a food web that sustains other animals in the ocean. Iron also plays an important role in the nutrition of these organisms.  When iron is too low, diatom growth can be reduced and their photosynthesis less efficient, resulting in low diatom abundance and decreased energy transfer further up the marine food web. In the part of the Pacific Ocean sampled by the Export Processes in the Ocean from Remote Sensing, or EXPORTS, program, iron is at some of the lowest levels in the global ocean and not at levels that can support high diatom growth. That being said, diatoms persist in this nutritionally challenged system, which drives the main goal of our EXPORTS experiments: to understand the impact that nutrients, such as iron, have on the role of diatoms in ocean carbon export.

To help us better understand this nutrient/carbon export relationship, we are performing large incubation experiments and following rates of nutrient use using natural diatom communities that we fertilize with precise amounts of nutrients to simulate natural changes that can occur in the environment. These experiments will improve our understanding of how these changes in nutrient availability affect diatom growth, diatom photosynthetic efficiency, and carbon production, as well as whether diatom species composition shifts or their gene expression alters in response to nutrient amendments.

In addition, we are also using radioactive isotopes of carbon and silica to track changes in diatom nutrient uptake rates and their metabolic activity.  Working with the rest of the EXPORTS science team, we will evaluate how shifts in diatom nutrient physiology drive diatoms through different food web pathways that lead to the export of diatom carbon to the deep sea.

In order to understand the growth rates and functions of diatoms in their natural environment, it is also important to study them in their natural conditions, which can be challenging when you are roaming the ocean in a large metal ship.  To ensure that our experiments are free from contamination, we take special measures to guarantee that we are collecting iron-clean samples, which is where our trace metal experts come into play.

On this cruise, there are three main techniques (a trace metal trifecta) we use to collect iron-clean water and the diatoms in this water:

One: Trace metal clean rosette system.

This is the bread and butter of collecting clean water samples from depth. We send the bottles down open, and close them at specific depths to bring that water back to the surface for measurements. These are standard sampling devices on all research ships, but ours is special in that we have swapped the nasty metal parts out for clean plastic parts, and the metal wire replaced with a stronger and metal-free Kevlar wire.

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A short montage of the rosette system deployment and recovery from the stern of the ship. Credits: Travis Mellett and Salvatore Caprara

Two: Clean sampling spaces

One of the biggest problems we have with keeping samples clean is dust, which is absolutely riddled with iron and is everywhere aboard the ship. To avoid this, we create spaces where we pump only the finest of filtered air in to fill our delicate lungs and keep dust out of our samples.  On the ship we have two places dedicated to clean sampling. The first is out in the trace metal van at the back of the ship where our rosette bottles live and are sampled from hot off of a rosette cast.

The second place we trace metal chemists feel comfortable enough to let loose and open our sample bottles is in our bubble in the main lab. The space is our clean, plastic fort we have constructed (and decorated) and pumped with clean filtered air (to puff the bubble) so we can still work in the main lab while avoiding the mess of our dusty and rusty neighbors.

Three: Trace metal surface tow-fish

The fish allows us to collect clean surface seawater by swimming out away from the dirty wake of the ship and sipping up that delicious iron-clean seawater through a plastic tube that we have hooked to a Teflon pump, bringing it right into our bubble.

Diatom Incubations at Sea

After collecting the diatom communities, we conduct a variety of experiments.  After fertilizing them with nutrients, we need to allow them time to grow and adapt to their new conditions, while maintaining otherwise natural conditions. To accomplish this, we use large deck board incubators, which are continually filled with flowing sea water collected from the surface to keep them at natural temperatures. The incubators are also wrapped in dark screening to help simulate light levels found within the water column where we collected each sample.

We monitor the response of the diatoms by measuring how fast they take up the nutrients under natural and fertilized conditions.  In some experiments we use radioisotopes of silicon and carbon to do this, and we collect the samples in a special van dedicated to radioisotope use. In other experiments we look at how diatom physiology responds to fertilization by measuring what genes diatoms are turning on and off as they encounter different conditions. For these experiments, bottles that have been growing in the incubators are brought inside to the bubble to be harvested and ultimately filtered in the ship’s main lab. Water from the bottles is passed through a series of filters using peristaltic pumps to collect the larger diatoms as well as any other smaller organisms that are in the water. These filters are flash-frozen in liquid nitrogen, acting as a cellular snapshot, freezing the metabolic status of each cell in place for future analysis.

This combination of field and laboratory work, bridging chemistry and biology, will provide data that will improve our understanding of why diatoms follow specific pathways through the food web of the upper ocean, providing a predictive understanding of the processes that lead to carbon export by diatoms, which are one piece of the biological puzzle pumping carbon to the deep ocean twilight zone.

by Montserrat Roca Martí / NORTHEAST PACIFIC OCEAN /

I am Montserrat Roca Martí, but I like to be called Muntsa, which is a Catalan name. I come from Barcelona, Catalonia, where I finished my PhD one year ago.

These last several weeks have been hectic and at the same time very exciting, as they included a wedding (my own, to be precise) and a big move from Barcelona to Falmouth, Massachusetts, where I am now a Postdoctoral Investigator at the Woods Hole Oceanographic Institution (WHOI). However, I didn’t spend much time in my new office. Instead, I spent most of my time getting equipment ready and packing over one hundred items of all shapes and sizes before leaving for Seattle in August.

All this activity is devoted to the Export Processes in the Ocean from Remote Sensing (EXPORTS) expedition in the Northeast Pacific. The primary goal of this project is to understand how carbon is converted from inorganic matter (carbon dioxide) to organic matter by phytoplankton. This forest of tiny photosynthetic organisms, mostly algae, represent the primary way the ocean is able to sequester carbon from the atmosphere, regulating Earth’s climate.

So here I am at 50ºN 145ºW aboard the R/V Sally Ride. I never would have imagined that I’d be spending my honeymoon in open ocean waters with 40 people, none of whom are my husband!

I belong to Café Thorium, a team comprised of amazing people who love espresso and also studying thorium in the ocean. We are interested in thorium—a radioactive, metallic chemical element—because it provides very valuable information about the transport of other elements, such as carbon, from the ocean surface to depth as particles sink. My main role in this expedition is to collect particles from different depths down to 500 meters in order to determine their composition and concentration in water. To do that, we use in-situ pumps, which are like underwater vacuum cleaners equipped with filter heads that we lower into the ocean to specific depths and turn them on. These heads contain filters of different pore sizes through which thousands of liters of seawater pass during four to five hours of intense pumping.

This operation requires strong and skillful people to lift nine heavy pumps and attach them to the wire that will transport them to the desired depths. Fortunately, two of our team, Spike and Claudia, are very experienced and have done this complex endeavor hundreds of times.

When pumps are back on deck, we have to remove the filters as quickly as possible before the organic particles degrade. This is Rock & Roll time for Blaire and me. We sub-sample as many as 50 filters so we and others can measure a variety of parameters, including microbial activity, pigments and carbon. Only then can we safely store our precious samples until further analyses back at WHOI and a few other institutions. So far, we have collected over 500 samples from more than 77 cubic meters of water (more than 20,000 gallons) and counting! This is how I am spending my honeymoon!

by Meg Estapa / NORTHEAST PACIFIC OCEAN /

Meg Estapa is an assistant professor at Skidmore College and leads the EXPORTS sediment trap team.  Her current work focuses on the optical properties of sinking particles and how these can serve as proxy measurements to help us better characterize the spatial and temporal scales of the biological pump. She is currently working aboard the R/V Roger Revelle.

One of the unusual things about the EXPORTS field campaign is the number of independently drifting instruments that we are using. These instruments include profiling floats, gliders, self-ballasted and moored sediment traps, and wave-powered profilers. Untethered from the ships, they multiply the observations we can make directly from the R/Vs Revelle and Ride. My team on the Revelle is responsible for all of the sediment traps and the wave-powered profiler (also known as the WireWalker). Right now we have seven different sampling devices to keep track of that are drifting out there in the ocean! Needless to say, in addition to our science, much of our mental energy at sea is taken up by one very important operational task: finding our equipment in the ocean.

Our sediment traps consist of cylindrical, rain gauge-like devices that capture sinking particles as they drift slowly downward over periods of days. They are attached either to a profiling float that carries them down to drift at depth (a neutrally buoyant sediment trap or NBST) or to an array of trap frames that dangle like a string of beads from a floating buoy at the surface (a surface-tethered trap or STT). None of the traps are connected physically to the R/V Revelle—we release them to drift on their own and then come back to retrieve them three to five days later. The ocean flows at speeds of a few kilometers per day, so the sediment traps won’t stay where we left them.

Recovering sediment traps requires us to engage in a carefully choreographed dance that begins with the deceptively simple-sounding task of locating the positions of our equipment in the ocean. All together there are usually 14 robots and sediment traps in the water out here at Ocean Station Papa, each with its own pattern of dives and resurfacings. These assets are spread out over a box that is roughly 30 nautical miles on a side (that is, 56 kilometers on a side, giving an area of over 3,000 square kilometers!). Visually spotting one of those tiny objects floating on the ocean’s surface is like finding a needle in a haystack.

To improve the odds of recovering our sediment traps, we rely on a collection of old and new technologies. The most important of these are GPS receivers that acquire precise location information, which is then transmitted via satellite back to computers on land. A second satellite connection allows us to access that location data over the Internet from the Revelle.  Some of our traps—the ones that have buoys at the surface—also send their GPS positions to the ship directly using radio transmitting beacons.  All of our traps have bright, flashing strobe lights that are highly visible at night, and some even have two! Finally, the buoy marking our drifting trap array carries an oldie but goodie: a metal radar reflector that bounces radio waves back to the antenna on the Revelle to be seen as a bright “blip” on the bridge’s radar screen.

When the time arrives to pick up a sediment trap, following the trail of GPS fix “breadcrumbs” is usually sufficient to bring the Revelle to within a mile or two of the recovery target. But a device drifting at the surface moves fast, and it takes a few minutes for GPS fixes to be relayed to us on the ship, so we’ll never find our target exactly at its last GPS fix. Especially for our smallest devices, the neutrally-buoyant sediment traps (NBST), the last and sometimes trickiest link is putting our eyes on the trap in the water.  Only the top of the NBST pokes out of the water when it’s awaiting a pickup—about the size of a yellow-and-gray soccer ball, with 25 feet of floating yellow rope streaming out beside it.

On a clear day it is just possible to spot an NBST from a mile away, and at night their flashing strobe lights are visible from a distance of perhaps two miles.  But the cloudy, misty weather out here is less than ideal.  On a typical trap recovery night, a visitor to the bridge of the Revelle would find a line of scientists and crew arrayed along the forward windows in near pitch darkness, hoping to be the first to catch a glimpse of the blinking strobe out on the water. The first exclamation of “I see it!” always produces a bit of an adrenaline rush for me! Following some expert ship handling to bring the Revelle right alongside the NBST, its precious cargo of samples and data is about to come back aboard.

by Sasha Kramer / NORTHEAST PACIFIC OCEAN /

Sasha Kramer is a PhD student in marine science at the University of California, Santa Barbara, and is currently working aboard the R/V Sally Ride for the EXPORTS field campaign.

I’m the type of person who likes to celebrate the little things. For instance, last week was my half birthday, and you’d better believe I celebrated with some peanut butter and M&M toast for breakfast (thanks Mark and John for stocking the galley with M&Ms!!!). I even did my best to pick out mostly blue M&Ms for an extra special treat. (Eeveryone knows blue M&Ms are the best color, right? This must be a scientific fact).

You might think there are few things to celebrate aboard a research vessel, but I would say that there are abundant opportunities for celebration with the right creative approach. The first cast of our CTD water sampler? The first sighting of the Revelle from the back deck of the Ride? The first successful float deployment? The rare rainbow stretching over the gray North Pacific? The one-hundredth nutrient sample? The one-thousandth nutrient sample?? These are all chances to break out a frozen peppermint patty and party on.

As anyone who has been on a research cruise can tell you, keeping morale up can be a tricky thing. Inevitably, things will go wrong, you will be short on sleep, and you will hit the point of feeling cranky or tired or frustrated or all three at once. Given my propensity for celebration, it is maybe unsurprising that my lab mate (and officemate back at UCSB and now bunkmate on the ship) Kelsey Bisson and I not only represent the Hydro Team on the Sally Ride, we are also the self-appointed official/unofficial morale boosters aboard. We may be filtering 120-plus liters of seawater every day, but we make sure to take breaks to enjoy the little things in life…breakfast on the back deck with a view of the stormy ocean, walkie talkie calls over to the Revelle (hi Nils and Brian!), and lots of chocolate covered almonds.

So how do we plan to boost morale for the rest of the team during these 35 days at sea, you might ask? We have a few things in mind, including those frozen peppermint patties we keep in our lab van on the back deck (and Reese’s peanut butter cups and dark chocolate Hershey’s kisses… as you might imagine, a lot of feeling happy on an otherwise tough day has to do with the availability of good candy). You can find us throwing an impromptu boat-wide rave in our lab van, with the red lights turned on and the glo-sticks we packed from home cracked and glowing. Maybe you’ll spot us sampling from the CTD with our portable (waterproof!) speaker blasting. Whether it’s Paul Simon or Usher, music is also a big part of keeping morale high. For this particular activity, it’s important to read the mood of the CTD cast. CTD stands for Conductivity, Temperature, and Depth which is measured with each water sample collected. Morning optics casts lend themselves well to calmer songs and gentle singalongs (think Vance Joy); evening calibration casts are more of a scene, with bumping bass and wild dance moves (while carefully sampling, of course).

We’ve also instated Sally Ride Saturdays. We have five Saturdays together as a group, and each one represents an opportunity to have some fun together at sea. Our first Sally Ride Saturday, as we cruised through Canadian waters, was Canada Day (complete with denim on denim; see Kelsey for reference). Goth Day fell on our bad weather Saturday: black eyeliner and lipstick and nail polish (and Avril Lavigne) ensued, demonstrated excellently by some of the ladies from Team Thorium. When the wave height increases this drastically, you can’t help but feel a little emo!! Our friends aboard the Sally Ride with us can look forward to upcoming Crazy Hair Day and Technicolor Day—it’s impossible not to crack a smile at various kooky hairstyles or feel your mood brighten at the sight of someone’s electric yellow foul weather gear!

While research cruises can be challenging and tiring at times, we’re also really lucky to be out in the North Pacific together. Sally Ride Saturdays are a way to keep our spirits up when the days feel long and we haven’t seen the sun in 48+ hours (it’s pretty cloudy up here at Station P). We’re all focused on our science, but we are also part of a floating family for five full weeks. A healthy dose of (M&Ms and) fun is all part of the experience. And our friends on land are certainly not restricted from celebrating Sally Ride Saturdays too—in fact, we encourage it! Crank up the ABBA and break out the feather boas! It’s Mamma Mia Day next Saturday! You know we’ll be doing the same around the CTD.

by Abigale Wyatt / NORTHEASTERN PACIFIC OCEAN /

Abigale Wyatt is a PhD student at Princeton currently working on the R/V Sally Ride for EXPORTS.

It’s been a little more than two weeks since we first set sail on the R/V Sally Ride for a month-long cruise to study how plankton in the ocean affect the carbon cycle and, ultimately, the climate. We left Seattle at the perfect time to get sunset photos of the city and surrounding hills. Most days, I still can’t believe I’m here.

I’m one of the more junior scientists aboard. I haven’t yet begun classes for a PhD program at Princeton’s geoscience department, and having graduated two years ago with a degree in math (not chemistry, biology, geology, or anything ocean-related), in many ways I’ve felt totally overwhelmed. But having just finished eight years in the US Navy without ever deploying on a ship, I am so excited to finally be at sea that I haven’t been shy about trying to jump in and learn everything.

Fortunately, the first few days were spent transiting, which meant I had little science to do and plenty of time to find my sea legs while learning methods associated with our collections at sea. Sometimes it’s like learning another language: CTD, thorium, pipette, RISO, potassium permanganate, acidify, and niskin, for example. It’s a combination of chemistry terms that sound familiar, technical equipment I’ve never heard of, and science-y-words I thought I understood but have never used in any real context. Coupled with that was the task of trying to develop a casual understanding of the logistics of a complex sampling grid that would be used to get samples for more than 40 scientists, some of whom are the biggest names in the field.

Like I said, somewhat overwhelming.

So naturally, I’ve sought out one of my go-to means of comfort: looking up at the night sky. As a major astronomy nerd, I was incredibly excited when I realized our trip would coincide with the annual Perseid meteor shower. I envisioned lying out on the deck after a hard day of science, being lulled by the calming rhythm of the sea while staring at the deep, dark sky, watching meteors streak through my favorite constellations. It was a beautiful mental picture.

Reality was not quite what I had imagined.

One few night, I went out on deck with a scientist from Woods Hole Oceanographic Institution who is working in my group. As we headed out, I chattered on about what planets were out, how great the Milky Way would look, and which direction we should face to catch the most meteors. In hindsight, I probably should have been more concerned with practical considerations: How wet will the deck be? What’s the cloud cover? What time do we have to work in the morning?

Turns out, boats are wet. Wet and cold. And since we were still moving toward our station, water was sloshing and spraying, with the boat rocking as we steamed ahead. I felt silly for imagining I would lie out and relax on the deck all night. Instead, we stood, necks craning, waves crashing, looking at as much sky as we could see through the clouds. Apparently, the Gulf of Alaska is a pretty cloudy place this time of year, so we were lucky to have even 50 percent visibility. Scorpio was missing its legs and Cassiopeia was totally hidden, but at least Jupiter was big and bright. I pointed out the Northern Cross when we saw it!

Our first meteor was super bright, probably one of the brightest I’ve ever seen. It was so fast we both gasped and pointed, then laughed at how excited we were. We saw more, including one with a tail so long it covered a quarter of the sky. While I’ve stargazed a lot since I was a kid, this was such a new experience. Seeing from horizon to horizon made it so much more apparent that we were sitting on top of a single round planet in the middle of this massive universe, tucked away in our quiet galaxy among stars and planets lightyears away.

Since then, clouds have obscured the night skies too much to try again, but the ship is quickly becoming a second home. Several times a day we send out a Conductivity, Temperature, and Depth (CTD) instrument, which is a water-analyzing device equipped with niskin bottles that fill up at depth. In the lab we do some chemistry, including acidifying our samples by decreasing their pH, followed by adding potassium permanganate to allow the water to release particulates. Finally, we count the thorium radiation from our filtered samples using a RISO machine, all so we can tell how carbon is cycled by the ocean. It’s been a lot to learn and, still, everyday there’s more.

The moments I feel overwhelmed, I just remind myself I’m lucky to be part of this huge project. Our research will help us better understand our oceans, our climate, and our planet.  And while I may be a novice in ocean science, being at the very beginning of my graduate studies, this has certainly been a most stellar way to start!

by Kelsey Bisson / NORTHEASTERN PACIFIC OCEAN /

Kelsey Bisson is a PhD candidate working with Dave Siegel at UCSB and is graduating this December. Her dissertation seeks to understand carbon flux in the ocean through data syntheses of satellite and field data around the world. She is currently working aboard the R/V Sally Ride for the EXPORTS field campaign.

Let me now say this: Step aside Jimmy Choo; steel-toed boots are having their moment. Indeed, “Every day is a fashion show and the world is the runway,” according to Coco Chanel. The same can be said for life on the R/V Sally Ride, as I’ll try to demonstrate.

Since I hopped aboard to join the hydro team (with Sasha Kramer, my fellow lab mate also working with David Siegel at UCSB), I’ve noticed there’s no shortage of runways on the Ride, from the hallways leading to the main lab, to the starboard side sampling deck, to her majestic bow with infinite views of blue. Those participating in this field campaign have been rocking this summer’s hottest treads and threads (hottest as in pushing 65 degrees Fahrenheit on a good day), and we expect these trends to hit the continent any week now.

Of course, living on a ship for five weeks with hazardous working conditions and tiny closets means that comfort and consistency here is key. But don’t confuse those two C’s with “boring.” Nay, when these sub-arctic silver seas aren’t stealing the show, Dr. Claudia Benitez Nelson’s yellow boots most definitely are.

They’re not just any yellow; they’re the bright, waxy color not unlike that of French’s yellow mustard. We’re left wondering, did the inspiration from this look come from an anticipation of the galley’s carefully curated condiments, OR is this a nod to Marc Jacob’s summer collection showing plastic yellow pieces as a comment on the dissonance between solar power and our longtime reliance on human-made materials? We may never know, but that’s the fun of fashion. She keeps the rest of her look simple, expertly showcasing how bright boots become the exclamation point of an outfit. “Amazon.com,” she says, when I ask where she got these punchy power pedestals.

Research scientists have been accused of being myopic at times, and that could be because we’re obsessed with microbes & their biogeochemical adventures far beyond that of the average Jack and Jill. Naturally, color us guilty as charged, but we also love the big picture. Perhaps nowhere is this more apparent than in the impossibly chic monochromatic getups of Drs. Collin Roesler and Xiaodong Zhang.

Collin is sporting an all-black “nekton noir” ensemble, maybe alluding to the expansive dark abyss below us, teeming with life and unknown probabilities that connect us all. (Nekton are all the organisms that swim freely in the ocean, as opposed to plankton, for example.)

Xiaodong Zhang’s all-grey getup can only be described as simply celestial, boldly celebrating the fact that we haven’t seen the Sun for days.

No, you will not find Louis Vuitton here on R/V Sally Ride. Nor will you find Dr. Jason Graff, a first round draft pick for chief scientist on R/V Roger Revelle, and a narrowly close second to Louis in his personal sense of style.

But you will find Taylor Crockford and her fierce flannels as she hauls hundreds of liters of seawater throughout our labs every day.

And my lab mate Sasha Kramer sporting some sensational stitches you’d half expect were designed by Donatella Versace herself.

“My mom got me these for my birthday,” she says. Through 20-foot seas, instrument mishaps, whipping winds, fake fire alarms, fake abandon ship alarms, diesel miasmas, and all too real sleep deprivation, I look around at all the hardworking happy fashionistas around me. I can’t help but wonder: Was Tim Gunn thinking of us when he muttered his words to live by, “Make it work”?

Daily migration of marine life to and from the twilight zone to the ocean surface.

by Ken Buesseler / NORTHEASTERN PACIFIC OCEAN /

“There is a 5th dimension beyond that which is known to man.  It is the middle ground between light and shadow.  It is an area, which we call, the Twilight Zone.” ~Rod Serling

Like many kids growing up in the 1960’s, I eagerly anticipated every episode of a black-and-white TV series by Rod Serling, expecting to be surprised, maybe even a little scared, of the mysteries of that 5th dimension he called “The Twilight Zone.” Little did I know that decades later as an oceanographer, I’d find myself at sea with over 60 like-minded scientists on a program specifically targeting the mysteries of another twilight zone—the one in the ocean that lies just below the sunlit surface.

What motivates us is the need to learn more about the role of the twilight zone and the animals that live there in regulating Earth’s climate. The story of how they do this actually starts at the surface, where microscopic marine algae, or phytoplankton, turn carbon dioxide in the water into organic matter via photosynthesis, much like plants on land.

This organic matter forms the base of the marine food web, which basically means that these microscopic plants serve as food for tiny marine animals called zooplankton, which are eaten by larger marine organisms and so on up to larger animals, like the fish that humans consume. Many of these animals come up from the twilight zone at night, using the cover of darkness to feed in surface waters and then disappear come daybreak. This is, in fact, the largest animal migration on Earth and happens around the globe every day, and we barely know it happens. 

But I am getting ahead of myself, because despite how appropriate Rod Serling’s description of the mysteries of “the middle ground between light and shadow” fits with what we are doing out here, peering with our instruments into the dimly lit depths, his TV show is not the origin of the name of a twilight zone in ocean sciences. In fact, at least as far back as 1915, text books included discussion of the “decrease in the abundance of life from the sunlit surface layers, through the twilight zone, to the zone of darkness,” as was written in College Physiography. 

Getting back to this cruise, most of the carbon either sinks out of the surface ocean directly or is carried by animals back down to the twilight zone in their guts and gets excreted. All of this sinking carbon becomes food for other twilight zone animals, with less and less remaining as you go deeper. This constant rain of organic carbon is known as “marine snow,” which drifts through the twilight zone and into the deep ocean.

Who cares how much organic matter or carbon goes though the twilight zone?  Well, if you are an animal living in the twilight zone, that’s your main food supply. As a human concerned with the potential for rising carbon dioxide levels in the atmosphere to disrupt our climate, it’s the quickest way you can get organic carbon to the deep ocean, effectively removing it from contact with the surface ocean and atmosphere for hundreds or thousands of years. 

Simply put, without the ocean storing carbon in the deep sea, the levels of carbon dioxide in the atmosphere would be much higher than they are today. And the last time they were this high, Earth was a much different place.

The tools I used to measure this cascade of particles carrying organic carbon to depth on this voyage includes sediment traps—something like a rain gauge that captures in a tube the sinking particles that are slowly settling through the water. A second method my group uses to measure sinking particles takes advantage of a naturally occurring element called thorium-234, which is slightly radioactive and decays with a precise 24.1-day half-life.  This clock allows me to calculate very precisely how much carbon is being carried from the surface through the twilight zone.  

It’s far too early to share my results from this cruise, but the importance and complexity of these links between twilight zone organisms and climate should not be underestimated. Like snowfall on land, organic carbon transport to the depths varies with the seasons and locations in the oceans, but in ways we cannot predict. And it is important for us in our efforts to better understand how quickly climate will change as we keep adding more carbon dioxide to the atmosphere. This job is so complex that it takes a village out here aboard two research ships, with autonomous vehicles in the water and support teams on land and satellites above. We work together to study these carbon flows and the living organisms in the twilight zone that create what marine biologist and conservationist Rachel Carson called the “most stupendous snowfall on earth.”

I don’t know if there are any episodes of The Twilight Zone to watch out here, but I do know there are many deeper mysteries we hope to unravel about the ocean’s twilight zone. 

Ken Buesseler is a senior scientist at the Woods Hole Oceanographic Institution. He has been working for decades on the ocean twilight zone and its impact on Earth’s carbon cycle. He is currently on the R/V Roger Revelle as part of the Export Processes in the Ocean from Remote Sensing (EXPORTS) field campaign.

by Dave Siegel / SEATTLE, WASHINGTON /

I am Dave Siegel, a professor of marine science at the University of California, Santa Barbara. I have been working for many years to implement  the Export Processes in the Ocean from Remote Sensing (EXPORTS) oceanographic campaign: a coordinated field effort to understand the interactions between life in the sea and Earth’s carbon cycle.

Last Thursday night, I watched “my baby” of a campaign sail away, as the Research Vessel Sally Ride left Pier 91 in Seattle for the northeastern Pacific Ocean.

While I am the science lead for EXPORTS, it’s not just my baby—it is truly a group effort. Two teams of scientists created the EXPORTS science and implementation plans, with a lot of input from the greater oceanographic community. The result is a campaign comprising more than 50 funded NASA and NSF investigators from nearly 30 institutions and many graduate students, postdocs and technicians, all excellently supported by the masters and crews of two Scripps Institution of Oceanography’s research vessels: the R/V Roger Revelle and the R/V Sally Ride.

EXPORTS aims to develop a predictive understanding of the interactions of life in the sea and Earth’s carbon cycle, which is critical for quantifying the carbon storage capacity of the global ocean. The oceans are Earth’s largest active reservoir, or storage, of carbon and carbon dioxide concentrations in the atmosphere and thus helps regulate our planet’s climate. This predictive understanding of the interactions of ocean life and the carbon cycle is especially important as we are seeing that our ocean ecosystems are changing in response to changes in Earth’s physical climate. To do this we need data to test and validate these satellite-based assessments and numerical model predictions.

We are trying to tackle a super hard problem—one I believe to be a true grand challenge in Earth System Science. Our approach is simply to follow the money. For ocean ecosystems, that currency is the energy stored in phytoplankton carbon from photosynthesis. The production of phytoplankton carbon is nearly balanced by its consumption by animals called zooplankton, which in turn provide the energy for the higher trophic levels of the sea, such as fisheries and charismatic megafauna (whales, seals, sharks, and the like).

The slight imbalance—roughly 10 percent of phytoplankton production globally—drives an export of organic carbon from the well-lit surface ocean into the dimly-lit twilight zone beneath. Within the twilight zone, microbes and animals of all description consume this exported organic carbon, utilizing their energy for metabolism.  This export of organic carbon from the upper ocean and their consumption within the twilight zone, along with ocean circulation, shape the carbon storage capacity of the global ocean and frame the two major research questions for EXPORTS.

Constructing a field campaign to identify and quantify the flows of organic carbon through the ocean is, of course, a major challenge. Phytoplankton physiologists need to assess phytoplankton growth rates and responses to perturbations in their required nutrients (nitrogen, phosphate, silica & iron). Zooplankton grazing and the carbon cycle impacts of their daily vertical migration to the sunlit layer of the ocean from the twilight zone need to be assessed.

Sediment traps that catch the rain of sinking particles measure the flux of sinking carbon as well as make detailed geochemical measurements that test how well our measurements of the individual pathways reflect the large-scale mass budgets needed to build and test satellite and computational models. Optical oceanographers make ocean color measurements that link the EXPORTS datasets to NASA satellite data products.  And I feel bad that I left out so many other individual research activities going on, but mentioning each of them would take up another two paragraphs!

The measurements needed to constrain the various food web and export pathways as well as adequately sample the highly variable ocean environment requires technologists that can overcome these challenges.  For example, the EXPORTS team includes robotics experts who build, deploy, and analyze data from an array of autonomous underwater vehicles (AUV) that sample ocean properties on time scales ranging from minute to years.

EXPORTS has also taken advantage of recent technological advances such as novel high-throughput microscopes and in situ imaging devices that take individual images of billions of phytoplankton cells as well as zooplankton and other various organic matter.  These images are then analyzed using advanced machine learning techniques to provide unique views of the structure of plankton communities.

Advancements are also available from the biomolecular sciences where metagenomic and bioinformatics approaches provide complementary ways to characterize plankton communities and their metabolism. Lastly, several projects include numerical modelers who will use computational approaches to help answer EXPORTS science questions.

The first EXPORTS field deployment will be to Station P (50N 145W) in the Northeast Subarctic Pacific Ocean. Station P (or PAPA) has been sampled and resampled over many decades—from as far back as 1949, when it served as an ocean weather station. Presently, Station P is the terminus of the Canadian Line P transect ocean research program and is an area of focus for the National Science Foundation’s Ocean Observatories Initiative project.

Last week, the R/V Roger Revelle and the R/V Sally Ride sailed to Station P. Both are floating laboratories that enable our research, but they will have different missions.  The R/V Roger Revelle will make detailed rate measurements and conduct a wide variety of experiments while the R/V Sally Ridewill make spatial surveys around its partner ship to assess the three-dimensionality of these processes.  These ship-based measurements will be supplemented by the array of AUVs.  Both ships and robots will make ocean optical measurements linking the EXPORTS field data to present and future NASA ocean color satellite missions.

EXPORTS is also planning a second field deployment in the North Atlantic Ocean in the spring of 2020 to provide contrasting data. Furthermore, NASA has supported a group of Pre-EXPORTS projects aimed at mining available, relevant data sources for use in EXPORTS synthesis analyses and to conduct modeling experiments to help plan this and the North Atlantic expeditions.

So I’m the science lead but I’m not sailing. Seems weird, but early in our planning we were worried about the coordination between all of the things going on. My job back home now is to help coordinate activities on the two ships and assist the four co-chief scientists in fouling off whatever curveballs that may come. I’m sure they will provide blog posts soon introducing themselves.

It is been a long time coming and I realized that as the R/V Sally Ride was sailing away. I have been there from the start pushing this along, so I suppose it is “my baby.”  I do want to thank all involved in the planning and implementation, including the program officers at NASA and NSF.

Further information about EXPORTS can be found at the NASA EXPORTS expedition team blog and the EXPORTS website.