By Mikayla Cote, Master’s student at the University of Rhode Island / UNITED KINGDOM /
After flying to the United Kingdom, the EXPORTS scientists were in quarantine for two weeks prior to embarking on a month-long research cruise. While there was still some last-minute work to be done before departure, for most of us this meant there would be no shortage of free time spent alone in our hotel rooms. As one of the lab mates cheering on the sailors from home, I wanted to be a part of the effort to facilitate remote activities as they anticipated their month at sea.
Cynthia Beth Rubin, an artist who has been working with our plankton ecology lab for over a decade, began offering her plankton drawing workshops over Zoom earlier on in the pandemic.
The plankton we study in our lab are microscopic plant-like and animal-like organisms, so Cynthia’s workshop aims to enable us to see and even feel these organisms’ movement through drawing since most do not know what microscopic plankton look like. While EXPORTS researchers have an idea of what these creatures look like thanks to microscopes, many in the general public don’t. Through Cynthia’s class, people are getting to see what plankton look like for the first time.
Many of those in isolation did not have access to paper typically used for drawing in their rooms, but it did not matter: lined paper, sticky notes, and even napkins were just fine. One of the postdocs in our lab decorated the hotel room T.V. with her sticky note drawings to enjoy for the rest of her time there. My favorite part of the workshop was holding up our finished drawings in front of our cameras to share with the group.
We spent a few hours together and while I cannot say exactly how those felt in isolation far away from home, this workshop offered a release to loosely draw and share sketches with others as well as a brief distraction from the global pandemic.
By Diana Fontaine, Ph.D. Candidate at the University of Rhode Island Graduate School of Oceanography / NORTHERN ATLANTIC OCEAN /
We have about one more week of full science fun left in the North Atlantic NASA EXPORTS campaign. It has certainly been a wild ride at sea given that we’ve experienced about four storms to date. However, even with the weather days, we have still accomplished an impressive amount of science.
My name is Diana Fontaine and I have been working with team grazer, alongside Heather McNair (post-doctoral researcher), Laura Holland (post-doctoral researcher) and Erin Jones (Ph.D. student). Our role in the project is to quantify microzooplankton grazing on phytoplankton. Microzooplankton are single-celled organisms that play an important role in the transfer of energy in the ocean. They are a key link between phytoplankton, the free-floating plants and algae of the sea, and larger zooplankton. Many species of zooplankton eat phytoplankton, which transfers energy to higher trophic levels. Every day, microzooplankton eat about 70 percent of the daily phytoplankton growth in the ocean. This is quite a huge loss factor of phytoplankton! Thus, understanding microzooplankton grazing rates has large ecological importance for carbon cycling in the ocean.
Measuring microzooplankton grazing involves many, many hours of pouring water and filtering. Sometimes I feel like all we do is pour water from one place to another. But so it goes as a plankton ecologist! The basis of these rates comes from measuring chlorophyll, a green pigment in phytoplankton cells that is used in photosynthesis, at the beginning and end of incubation experiments. But first we must collect the water used in our experiments from the CTD Rosette, a device that we use to measure seawater properties like conductivity, temperature and depth as well as collect seawater samples. After collection, we incubate the water in tanks on the back deck of the ship. These tanks are covered in various layers of mesh screens to imitate the light levels at different depths in the ocean. The microzooplankton hang out in the tanks for about 24 hours to give the microzooplankton a chance to have a feast on the growing phytoplankton.
Once time is up for the experiment, we again filter more water – this time to observe how much chlorophyll increased or decreased during the incubation. There are some details to these experiments that I won’t describe here. However, overall if chlorophyll increased during the incubation, then there was more phytoplankton growth than the microzooplankton were able to graze. And vice versa – if there is less chlorophyll at the end of the incubation, then that mighty microzooplankton had quite the snack! On some days we have observed happy snack time for the microzooplankton,while on others there didn’t seem to be much grazing happening at certain depths in the water column. We’re looking forward to examining these rates in greater detail once back on land.
For the remainder of the cruise, we plan to carry out a couple more grazing experiments. Both the length of this cruise and the periodic storms have allowed us to collect data under varying environmental conditions. This will make for an exciting data analysis adventure, especially when we place our results in the framework of the broader NASA EXPORTS project.
Once this next week of science is complete, we will pack up all of our gear and samples for shipment back to the United States. While it will be sad to leave our floating home for the past month or so, I look forward to the data analysis, collaboration, and writing up our results back on land. Throughout this whole experience, we have been incredibly lucky to have the helpful support of the NASA Project Office as we navigated the traveling, quarantining, and sailing during the pandemic. It has certainly been a rewarding experience to join along for the ride.
By Delfina Navarro-Estrada and Shannon Burns, oceanography graduate students at the University of South Florida / NORTH ATLANTIC OCEAN /
In the sunlit portion of the ocean exist single-celled microscopic organisms called phytoplankton. They are called the ‘grass of the sea’ because these tiny plants and algae perform many of the same ecological functions as plants on land. As such, they provide energy to the organisms higher up in the food chain that feed on them, forming the foundation of many marine food webs. Through a process called photosynthesis, phytoplankton also remove carbon dioxide from the atmosphere and use it to produce sugars and other organic compounds that they require to live and grow.
Because photosynthesis requires sunlight, phytoplankton thrive in the surface layer of the ocean. Eventually some of the carbon in phytoplankton is exported out of the sunlit surface layer to deeper waters where it can become sequestered from the atmosphere for decades to centuries. Export occurs through different mechanisms, including when organisms that get their carbon from eating phytoplankton die and sink, or produce fecal pellets that sink. Most of the sinking carbon ends up being dissolved back into the water column before ever reaching the deep sea or the seafloor. The small fraction of organic carbon that does reach the seafloor, however, ends up being buried and stored for hundreds of thousands of years. This process of carbon export is known as the biological carbon pump.
Net primary productionis a term used to describe how much carbon the phytoplankton community incorporates into their cells via photosynthesis, minus the amount of carbon released through respiration. It can be limited by the supply of nutrients and sunlight in the water column, both of which vary over space and time across the ocean. Those needed in large amounts like phosphate, nitrate, and silicic acid, are called macronutrients . Other nutrients are needed in comparatively smaller amounts and are called micronutrients, which include many trace metals like manganese, iron, cobalt, nickel, copper, zinc, and cadmium.
Phytoplankton are so good at gathering required nutrients from seawater that they can run out. When that happens, their growth is slowed or stops and their composition changes in ways that affect export. They can become sticky, aggregate and sink quickly, or become poor food sources for their predators, reducing grazing and the amount of export by zooplankton that eat phytoplankton and produce fecal pellets. In these ways and others, the nutritional status of the phytoplankton can change how efficiently the biological pump moves carbon from the surface ocean to the deep sea.
As part of the EXPORTS program, we are identifying how macronutrient and micronutrient availability affects phytoplankton community composition and their physiological state to understand how these factors drive phytoplankton carbon through the biological pump.
In 2018, our team sailed in the North Pacific, a region with highly stratified waters with minimal nutrient input. Now in 2021, our team is sailing in the North Atlantic, a seasonally stratified region where eddies move nutrients from the ocean depths to the surface through a process called upwelling. We are using a combination of ultra-clean trace metal chemistry combined with the tools of molecular biology to understand how phytoplankton are responding to the changes in nutrients in their environments.
Our team is trying to understand how different organisms respond to the changing nutrients? Working with the rest of the EXPORTS science team, we will combine measurements of carbon export, and ultimately the amount of carbon dioxide sequestered from the atmosphere.
By Ken Buesseler, Woods Hole Oceanographic Institution /NORTHERN ATLANTIC OCEAN/
For those of us who grew up watching Gilligan’s Island, we all know the fateful story of the “three-hour tour.” Well, as this oceanographer knows, that TV storm is not that different from the weather we are facing out here in the North Atlantic on the research vessel Sarmiento de Gamboa.
Our story takes significantly longer than three hours, as we set off at the beginning of this month on a three-week tour – 18 days to be more exact. Add in three years of planning the science mission, plus two years of coordinating three research vessels to rendezvous at the same time and location, one year of COVID-related delays, two weeks of quarantine in a hotel in Vigo, Spain, and you get the idea of how much time and effort we expended before we even left the dock.
Our mission is to gain a better understanding of the mysteries of the ocean’s twilight zone. The twilight zone refers to the vast layer of the ocean below where sun penetrates and above the abyssal dark ocean. At the surface, marine plants, or phytoplankton, convert carbon dioxide into organic matter just like plants on land. This organic carbon is the food supply eaten by zooplankton, or microscopic animals, and then fish and other animals up the food chain. As they eat, they expel fecal matter – yes, poop – which attaches to other particles in the water, and forms what scientists call “marine snow.” Typically, only a small fraction of the marine snow makes its way downwards through the twilight zone to the deep sea.
The reason we need to pay close attention to marine snow is that it plays an important role in climate regulation. Marine snow carries carbon with it and settles into the deep ocean, which influences the levels of carbon dioxide in the atmosphere and thus affects our climate and weather on land.
So we are out here to capture the marine snow fall, to better understand its variation, and predict how it will change in the future.
Mother Nature has her own agenda.
Two days after sailing northwest from Vigo, Spain, we reached our study site where two vessels, the RSS Discovery and the RSS James Cook, have already started sampling.
So far so good.
After 36 hours, winds pick up to 50 knots and seas quickly swell to 15-20 feet or more. The Captain makes the call to stop all science operations. At that point, we double-check all the ropes, ratchet straps, and bungies holding down our expensive scientific gear in the lab, feel gratitude for having strong, seafaring stomachs (or at least I do) and wait.
With the hatches locked, we hear and feel waves crashing into the ship. We wonder if the rolls can get even larger than 30 degrees. We head 100 miles south to avoid the worst of the storm. And we wait.
We chat with each other, read books, and watch videos. We go to normal meals in the mess, amazed that the cooks on board can still prepare a full, hot meal in these conditions. We use one hand to steady our plates, the other hand to hang onto the table. Occasionally we manage to shove some food in our mouths.
After four days, the weather improves enough to allow us to sample again.
We enjoy 36 hours of continuous science operations. At one point, we bring all three large vessels together (a few ship lengths apart) to compare results from common instruments used on each ship.
Our ship carries new technologies to add “eyes in the twilight zone” using different on-board and robotic imaging systems that we deploy for autonomous missions.
A second ship carries out survey work, following and crossing circular tracks that the ocean currents make out here called eddies.
The third ship stays faithfully in the center, following the same patch of water, focused largely on marine biological processes and their chemical and physical controls. They deploy unique devices to capture the marine snow fall directly.
Quite simply, we need to work together to put all the puzzle pieces together. But Mother Nature has more in store for us.
We get hit a second time with 48 hours of waves and winds. This time we head north to avoid the worst of it.
And again, I find myself sitting and waiting, not stranded on an idyllic island like Gilligan and the party of the Minnow (the professor character always appealed to me the most) but stuck on a 230-foot research vessel, waiting to get back to the work we came here to do.
Despite the rough seas, I love my job. The understanding we gain by visiting these remote and sometimes stormy places, makes up for the discomfort and effort it takes to be here.
As we weather the final dregs of the storm, I can’t get the theme song from Gilligan’s Island out of my head “just sit right back, and you’ll hear a tale…”
I’ll certainly have some tales to share.
We’ve already been sharing data between the ships. In less than a week, we will pack up our gear, and bring our samples and data back to the Woods Hole Oceanographic Institution. We will share our science stories, as well as stories of raging seas, and the challenges we face just to do our jobs.
All these experiences remind us of what we can and can’t control as we work to better understand this ocean planet.
By Zachary K. Erickson, NASA Goddard Space Flight Center / GREENBELT, MARYLAND /
The ocean is full of eddies – swirling water masses that are the ocean equivalent of hurricanes. In comparison with their atmospheric counterparts, eddies are smaller, longer-lived, and far more numerous: at any given moment, well over 1,000 eddies exist throughout the global ocean, with diameters typically between 30 and 200 miles (about 50 to 300 kilometers). On average they last for one or two months, but about 20% last for four months and a small fraction can last for over a year.
We decided to locate the North Atlantic EXPORTS field deployment within an eddy because eddies tend to trap water masses in their core. This means that if we put multiple instruments in the eddy core, we can be pretty sure that they will stay close together. In a campaign involving dozens of individual instrument platforms, it is much easier to organize and understand the measurements when they are all near each other! Additionally, if the eddy core primarily contains trapped water, we can interpret changes in the water properties – such as a decrease in nutrient levels or an increase in biomass – as resulting from biological processes happening within the eddy, rather than from other external factors.
The main way we look for eddies is by using data from a constellation of satellites continuously orbiting the earth. These satellites use radar to very precisely measure the height of the ocean surface. On a global scale, these measurements help scientists track sea level rise. Locally, we use these measurements to track eddies, which either look like hills or valleys in sea surface height depending on if they are rotating in a clockwise or counterclockwise direction (in the northern hemisphere; this is flipped in the southern hemisphere). A sea surface “valley” is directly analogous to the low pressure associated with hurricanes, which rotate in a counterclockwise direction (in the northern hemisphere).
Once we find an eddy, we try to predict how long it will last. For the EXPORTS field deployment, it was important to pick an eddy that was going to last for at least a month, which is the length of the main part of the deployment. We look at data from years past to identify characteristics of eddies that are long-lived, such as their size (bigger is better) and how symmetrical they are (circular eddies are better than oblong shapes). We also use numerical simulations to drop “particles” in a given eddy and track whether or not they appear to be trapped within the center or if they escape from the eddy. From these we generate a prediction for each eddy of how long, and how well, it will trap water masses within its core. For this experiment, we want a long-lived eddy that effectively traps water!
After we have a small number of candidates, we need measurements from instruments in the water. It is very important to know what the eddy looks like beneath the surface, below where we have data from satellites. The EXPORTS project is centered around measuring carbon “export”, or how carbon locked up in biomass is transported from the ocean surface to the deep ocean interior. So, it is important that our chosen eddy effectively trap water masses down to about a thousand feet (about several hundred meters).
Initially, we get these measurements from ocean gliders, autonomous platforms that adjust their density to move up and down within the upper 0.6 miles (about 1 kilometer) of the water column, taking measurements of temperature, salt concentration (salinity), oxygen levels, and biomass along the way. Three gliders were deployed in early April, and these measurements were supplemented by data from three research ships in May, as well as the aforementioned dozens of platforms deployed within and around the eddy.
Throughout the course of the field deployment, a group of scientists on “shore duty” (including numerous institutions such as NASA Goddard Space Flight Center, University of Washington, University of Rhode Island, CalTech, University of California Santa Barbara, Woods Hole Oceanographic Institution, and the National Oceanography Centre in the United Kingdom) use all of these data to track daily changes in how our chosen eddy is evolving over time, making sure that we center measurements on the core mass of trapped water in the center. There’s still a chance that the eddy will break up, but two-thirds of the way through the mission, all evidence points to our having made a good choice in picking an eddy that will stay present at least throughout the course of this field deployment, and perhaps for many weeks or months afterwards!
By Sara Blumberg, NASA’s Goddard Space Flight Center and Inia Soto Ramos, Universities Space Research Association / GREENBELT, MARYLAND /
Pandemics can change the plans of nearly everything, including ocean research.
That’s exactly what happened with EXPORTS. In 2019, the original North Atlantic Expedition along with its active research projects were cancelled.
Despite the setback, the group kept meeting and sharing results. With strong support from our funding agencies, the EXPORTS team started looking for options to do the second expedition.
After a lot of challenges, the idea of a field campaign started to become a reality. In April, researchers from all over the world landed in England to begin two weeks of quarantine before setting out for the seas.
Here’s what happens when a group of scientists are asked to isolate:
1. COVID Testing
So many tests! Scientists had to ensure regular negative test results before they could get on the boat. The result? Three ships of crew all COVID free!
Video caption: Instructions on how to take a COVID test during quarantine. Video credit: NASA EXPORTS field campaign
2. Cheese making!
The daily supply of milk at the hotel was overwhelming for our scientists, so ideas and recipes started overflowing the group chat! One of the clever ideas was to use some of the pantyhose. Yes, pantyhose have a use in oceanography.
Pantyhose are used to hold the filter pads that go in liquid nitrogen to keep them very cold until samples get processed. Dewars, a double-walled flask with a vacuum between the walls, have a metal container that sometimes issues when opening and closing. We found that the filter pads can escape and fall in the bottom of the liquid nitrogen bottles. To prevent this ,we put the histoprep (with filters) capsules inside the pantyhose leg section and tighten it with a string. This keeps the filters safe, making it easier to pull out.
After a bit of online DIY searching, EXPORTS researcher Sue Drapeau debuted her hotel-quarantine-made paneer cheese. While that surely made good use of the extra milk, it surely sparked a few complaints of spoiled milk smells around the hotel!
3. Knitting Hats
Biological oceanographer Colleen Durkin had a quarantine goal in mind – knitted hats. During her two weeks of isolation she knitted a hat for each member of her team. She dubbed them the “Mesopelagic Fade” and were all ready when they set sail. In knitting jargon, a “fade” is a method for transitioning across a color gradient. The mesopelagic is the depth gradient that we are studying.
Finished my 2 week quarentine project just in time. “Mesopelagic Fade” series for the EXPORTS trap team. pic.twitter.com/0wwajGEiRW
Tweet caption: Researcher Colleen Durkin’s finished hats for her team. Credit: Colleen Durkin
To bring everyone together, researchers spent their time making cards, painting, and doing trivia nights. They also engaged in a virtual Plankton Action Drawing Workshop with Cynthia Beth Rubin. Cynthia is a digital/analog artist, and has been drawing plankton with the Menden-Deuer Lab for many years and incorporating it into her own work.
Scientists spent a lot of time looking out of their windows. The weather ranged from snow sightings, beautiful spring days and a continued question of when the quarantine would be over.
For the researchers, the quarantine impacted everyone differently. Stay tuned for more personal accounts of what it was like to do field work while away from loved ones.
By Sara Blumberg, NASA’s Goddard Space Flight Center and Inia Soto Ramos, Universities Space Research Association / GREENBELT, MARYLAND /
When we talk about climate change, we tend to think of lush forests with giant trees that passively trap carbon dioxide from the atmosphere and use them for food in a process called photosynthesis.
The ocean might not have giant trees, but it has microscopic, little plants known as phytoplankton that do the same thing.
In a rapidly changing planet, carbon continues to play a big role, especially in altering our ecosystems. The NASA-led field campaignExport Processes in the Ocean for Remote Sensing (EXPORTS) wants to learn how this chemical element is impacting the ocean, especially in a place right beneath its surface called the “twilight zone.”
This past month more than 50 scientists from all over the world have been conducting large-scale studies from the surface of the twilight zone in the Northern Atlantic.
So why is the twilight zone so important? In short, researchers don’t know much about it.
Carbon dioxide dissolves in the ocean, making it available to hungry phytoplankton that, in the presence of sunlight, will bloom. In some cases, these blooms will paint surface waters in beautiful shades of green and brown that can be observed even from space!
While phytoplankton keep getting healthy and chubby, other sea creatures such as zooplankton will feast on them. Eventually, carbon is incorporated in the ocean food chain and is released in the form of organic matter via decay (think feces)!
Some of that decay material gets reused within the surface ocean, while others will sink to where sunlight fades –the twilight zone! During this process, carbon can get reused, ride with the currents, go up and down the ocean along with creatures that migrate along the water column, or simply make it to the seafloor where it may be stored for years to millennia.
Understanding how much carbon is taken up and exported to the deep ocean is a key question for understanding climate change and improving model predictions.
Back in 2013, a group of oceanographers and scientists alike met at the University of California, Santa Barbara and drafted a science plan for a field campaign mission to study how carbon moves from the ocean surface to seafloor.
That science plan was published in 2015 after a rigorous and extensive scientific review. EXPORTS became a reality in 2018 when 18 projects, dedicated to address the science plan questions, were funded by the NASA Ocean Biology and Biogeochemistry and National Science Foundation.
The first phase of the EXPORTS project was a successful field campaign in the North Pacific Ocean in 2018 led by a stellar team of scientists, two University-National Oceanographic Laboratory System vessels (R/V Sally Ride and R/V Roger Revelle) and state of the art technology.
On April 22, 2021, the EXPORTS North Atlantic Expedition began with two research vessels named the RRS Discovery and RRS James Cook. The shipsalso deployed gliders, drifters, moorings; other edge-cutting oceanographic instrumentation began field preparations.
The EXPORTS team was joined by Woods Hole Oceanographic Institution’s ocean twilight research program onboard the Spanish vessel R/V Sarmiento de Gamboa. The galore of technology is represented by a diverse science crew that will study this region for about 30 days. Research will range from microscopic creatures, such as viruses and bacteria, to the dynamic circulation and biogeochemical processes driving the carbon cycle during the spring blooms in the North Atlantic ocean.
Follow along as NASA details their journey, which started with two weeks of quarantine.
Adrian Marchetti is an associate professor in the department of Marine Sciences at the University of North Carolina at Chapel Hill and was aboard the R/V Roger Revelle for the EXPORTS field campaign this August and September.
So perhaps you read about the EXPORTS cruise and have heard about this place called Station P. You are now probably wondering why NASA would fund a mission that includes two research vessels spending over three weeks at this place? Well, to some, Station P (also known as Ocean Station Papa or P26) is simply a point on a map in the middle of the North Pacific Ocean – latitude 50 degrees north, longitude 145 degrees west. But to others it is much more than that.
Historically, in the 1950’s the Canadian weather service established a program to position ships off the west coast of Canada to forecast the incoming weather and sea state conditions. Station P was occupied for six weeks at a time by one of two alternating weather ships. Spending that much time at sea at one location can get, well, boring. To help pass the time, the crew collected samples and obtained measurements of the ocean. In the early days, these included bathythermograph casts that measured ocean temperatures at various depths. As more sophisticated approaches were developed to measure additional ocean properties, they started collecting samples for analysis of seawater chemistry (salinity, nutrient concentrations, etc.), chlorophyll concentrations (used as a proxy for phytoplankton biomass) and performed the occasional plankton haul to discover what critters called Station P their home.
A few decades later, with the development of new satellite technologies that enabled the monitoring of weather conditions from space (thanks NASA!), the weather ships became obsolete, and so the program was discontinued in the early 1980s. But as a result of the decades-long time series, what became apparent was the critical need for long-term monitoring of the ocean. So the Department of Fisheries and Oceans Canada established the Line P program made up of a transect where Station P is the endpoint. Today the Line P program is one of the longest ongoing oceanographic time series.
So what’s so special about Station P? Well, this mostly depends on who you ask. For one, the North Pacific is one of the largest ocean basins. It undergoes periodic oscillations on approximately decadal timescales that can influence global climate. The North Pacific also represents the finish line of a long conveyer belt that transports deep waters from far-off regions of the planet to the surface.
From a biologist’s perspective (yes, I am a biological oceanographer), Station P also happens to reside in a so-called High Nutrient, Low Chlorophyll (HNLC) region where the growth of phytoplankton is limited by the availability of the micronutrient iron. This is a relatively new discovery, and although evidence for iron limitation in this region dates back to the early 1980s, the most compelling data was obtained in 2002 when Canadian scientists performed a large-scale iron fertilization experiment at Station P. The experiment was named the Subarctic Ecosystem Response to Iron Enrichment Study, or SERIES.
I participated in SERIES as a graduate student while completing my Ph.D at the University of British Columbia. My Ph.D. research focused on pennate diatoms (a type of phytoplankton) of the genus Pseudo-nitzschiathat that dominate iron-induced blooms in many HNLC regions across the globe .
These particular diatoms can achieve rapid growth rates at iron concentrations that would leave their coastal counterparts fully anemic and left for dead. These oceanic diatoms have many adaptations to survive in low-iron waters and sometimes flourish when new inputs of iron, which are primarily from atmospheric dust, periodically enter the ocean. Prior to SERIES I joined a number of Line P cruises adding iron to diatoms in bottles to make them bloom. We now know that not all phytoplankton are created equal and, given their extensive diversity and important role in contributing to the planet’s carbon cycle, we need to keep studying them.
During the SERIES experiment we also created a massive bloom of diatoms (you guessed it, dominated by Pseudo-nitzschia) as a consequence of adding several tons of iron to an initial patch of seawater approximately 80 square kilometers in size. At the peak of the bloom, the patch had grown to a size of about 700 square kilometers, representing one of the largest experimental manipulations on the planet to date. Fortuitously, the patch was captured by a satellite image of ocean sea surface color at the peak of the bloom, the only such image obtained throughout the entire SERIES experiment. Indeed, the North Pacific Ocean is known for having dense cloud cover almost every day of the year.
So this brings us back to EXPORTS, which marked my seventh trip to Station P, so I am beginning to feel quite at home there. With so many measurements obtained from Station P over the span of almost seven decades, what possibly is there left for us to learn? Well, to put it bluntly—lots! In my career I have been fortunate enough to participate on a number of field missions, and by far the EXPORTS program constitutes one of the most extensive scientific undertakings I have been part of. Although, this time we were not adding iron into the ocean but instead making observations of its natural state by following the same parcel of water that passed through Station P.
A primary objective of EXPORTS is to quantify the components of the ocean’s biological carbon pump, the process by which organic matter from the surface waters makes it’s way to ocean depths. Scientists aboard both ships measured the processes that constitute the initial formation of organic matter by phytoplankton all the way to its export from the upper ocean or it’s remineralization back into inorganic carbon.
Bacteria or little animals known as zooplankton that feed on phytoplankton, bacteria, or other small animals perform both these processes. Other scientists were focused on measuring the fate of the carbon that does sink out of the upper ocean by looking at the overall amount and what forms these sinking particles take. It was quite an undertaking that had a lot of moving parts, all happening on two moving ships.
There was also a large effort to obtain as much information about this region using a multitude of underway systems that includes mass spectrometers, particle imaging “cytobots” and flow cytometers, autonomous instruments that includes gliders, floats and wire walkers, and instruments that collect optical measurements. Although we may consider ourselves lucky if we are able to obtain more than a handful of satellite images of ocean properties from space, we are making similar measurements from ships. We are also making new measurements that do not currently exist on satellites but perhaps will one day so that we can continue to develop new ways of monitoring our precious planet from above.
Through the years we have learned a lot about how this part of the ocean operates, yet there is still so much more for us to learn. This is especially important at this period in Earth’s history as we continue to place considerable pressures on our valuable ocean resources.
And as for that postcard, well lets just say that it’s in the mail.
Alex Niebergall is a PhD student in Earth and Ocean Sciences at Duke University and worked aboard the R/V Sally Ride in the North Pacific in August and September.
Before I joined the science crew aboard the R/V Sally Ride and set sail for the middle of the Pacific Ocean for my first ever research cruise, I can honestly say I did not know what to expect. Would it be an adventure? I hoped so. Would it be long hours in the lab? Undoubtedly. Would it be like stepping into National Talk-Like-A-Pirate-Day for an entire month? Maybe not. What I did know is that the research cruise meant 34 days on the open ocean doing what I love, and that was the only enticement I needed to sign up!
For me, it has always been about the ocean. Don’t get me wrong, I love science. I know this because my time as a researcher has taken me to far more windowless labs in the basements of old science buildings than remote, dream-like field locations, and I have enjoyed every second of this work too! But even this windowless basement science ties back to Earth, the environment, and most importantly (in my eyes) the ocean. Throughout elementary and high school, I was drawn to science and math because they gave me new ways to look at the world around me. Suddenly, every baseball game was a math problem—the velocity of the pitch, the angle of impact, the parabolic motion of the ball as it headed into the outfield (why no… I’ve never been very good at sports, how did you guess?).
As an avid outdoorswoman, science unlocked even more secrets. Physics and geology courses taught me about wave motion and erosion. Biology, ecology, genetics, and evolution classes allowed me to go to tide pooling and appreciate the radial symmetry of an ochre sea star while understanding its predatory role in the intertidal ecosystem. A firm grasp of chemistry allowed me to look at the ocean on a much smaller scale—a system of salinity gradients, dissolved nutrients, and pH balance. (Not to mention that chemistry makes cooking more interesting!) These subjects were interesting because I saw them every day around me, connected and continuously in flux, influencing each other in every way and giving me a new appreciation for all the activities and places I already loved.
Oh the places we’ll go…
In truth, science has taken me to some of the coolest places I could possibly imagine. As an undergrad, I went to field sites in the depths of the Northern California wilderness that look so wild and untouched they could be the set for the next Jurassic Park movie. I’ve been to redwood forests studying ecosystem dynamics. Science training took me to the underwater kelp jungles of Monterey Bay, California, and offshore Oregon where I learned, among other things, that measuring baby sea stars (sometimes the size of my thumb nail) becomes infinitely more challenging in a surge that forces you 8 feet in either direction. I also learned that sea creatures (specifically sea otters and trigger fish) have the ability and the instinct to irreparably damage science equipment, but THAT is a story for another time! Research took me to the underwater paradise that is the coral reefs of Indonesia, where night diving with bioluminescent dinoflagellates meant that the water around me perfectly mirrored the stars that sparkled out of the darkness overhead.
Now as a brand new graduate student in Earth and ocean science, I found myself living on a floating laboratory in the middle of the Pacific Ocean, with a view of the waves as far as the eye can see in a blue hue that is unlike anything I ever saw in my life. My group’s project aboard the ship was focused on quantifying how the plankton communities in the ocean influence carbon export by estimating the net community production at the ocean’s surface. We did this by measuring biological oxygen concentrations in the surface water and pairing these data with genetic analyses of the microbial community. These measurements allowed us to infer how much carbon was being taken up by biological processes and thus, taken out of the atmosphere.
With this project, those same subjects I learned to love in the tenth grade—chemistry, ecology, genetics, math—tied together (with the help and expertise of many, many other dedicated scientists) to give us a comprehensive view of what is happening in the ocean and how it affects our planet’s climate.
To some, the idea of being a floating speck in the middle of the ocean may seem isolating (or at the very least, nausea-inducing). To me, it is the coolest place I’ve ever been. The view reminds me that I am a small part of something big, not just as a junior scientist in the immense scientific undertaking that is the EXPORTS project, but also as one small human in the middle of an enormous planet that we have the privilege to explore, admire, question, and hopefully understand. Today, I am a happy, and very lucky, scientist because I was on this wild adventure, working alongside some of the most inspirational and dedicated scientists I have ever met.
But tomorrow? Tomorrow I am eagerly waiting to see where science will take me next.
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.
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.