Hydrothermal systems are an important component of Earth’s “heat engine,” and account for approximately 25 percent of the planet’s total heat loss. They also provide important pathways for heat and chemicals to travel from inside the Earth to the ocean and the crust.
Within a hydrothermal system, seawater percolates down into the crust, as it is heated by magma, it reacts with oceanic crust and changes composition, then rises back to the seafloor, where it forms high-temperature black smoker vents, as well as lower-temperature diffuse flows (see figure 1). Heat is the primary driver of this system, and it also helps support life near hydrothermal vents. Despite its’ importance, measurements of the heat output of seafloor hydrothermal systems at mid ocean ridges, have been very limited.
My research deals with three very simple things: water, rocks, and heat. But for most of my career, I’ve dealt with these things in a conceptual way—I create models of the way heat and fluids move through the rocks beneath the seafloor and are influenced by such variables as the permeability of the seafloor, the rate at which magma is replenished after an eruption, and the length of time seawater remains beneath the seafloor before flowing back into the ocean. I have also “cooked rocks” in the lab, to resemble seafloor hydrothermal conditions.
Much of the work that I and many other scientists do is hampered by lack of data-such as heat flow from seafloor. And to collect such data, one has to make a trip to an actual study area. My study area just happens to be 1.5 miles under water and spread out over square miles of rugged seafloor.
In the eight years since completing my master’s research at Virginia Tech on the hydrothermal system at 9°50’N, never once have I seen the seafloor or my study area up close. I used to watch videos of hydrothermal vents on YouTube, but nothing could have prepared me for the experience of diving in Alvin.
As we were descending, I was glued to the porthole. When the seafloor came into view, I instantly started smiling. It was right there, within arm’s reach, in all its glory!
The shiny pillow lavas, the shimmering diffuse flow, the grumpy looking crabs, and the Tubeworms were just some of the amazing sights. And after a short trip towards the axial ridge of the mid ocean ridge, the hydrothermal vents came to sight, looking like a complex skyscaper, with various black smoker chimneys and diffuse vents all around. This amazing journey lasted eight hours, it was the most awesome eight hours of my life. I will never forget it!
My 3-week journey on the Atlantis has been great and working with both the Alvin and Sentry teams has been an incredible learning experience.
Post By: Carolyn Tepolt, Woods Hole Oceanographic Institution
Alvin weighs about 40,000 pounds and its manipulators can crush rocks. But every so often, when the sub encounters a crab on the seafloor, the crab will raise its claws as if to pick a fight with the great, white beast invading its territory.
I’m here to study these vent crabs. They’re widespread members of hydrothermal communities that patrol tubeworm mounds and mussel beds for food, stark white except for a dapper hint of black on their claws. With so little pigment, these crabs are as translucent as fine bone china. Hold one up to a light, and you’ll see the outline of parallel gills framing the heart, nestled under the digestive organ, a dark, stretched-out M across the back that looks like a child’s cartoon of a seagull in flight. The females can be even more striking, with a princess-pink scrawl of eggs nearly glowing just beneath the shell.
Despite their delicate appearance, they are extremely hardy beasts. They live under enough pressure to crush a car, but can survive on the surface for months or more. They also regularly shuttle between the cold of the seafloor and the heat of the vents, two starkly different environments. The first is full of food and energy, but also hot, toxic and devoid of oxygen. In contrast, the surrounding seafloor, although healthy and oxygen-rich, is cold and largely lifeless. Switching between the two is like walking outside on a beastly hot day from an office where the AC is constantly set too low, but on an even greater scale.
On the ECS leg of the cruise, I’m planning to test this versatility. Once the crabs are on board Atlantis, I’ll connect them to a device that shines infrared light through their carapace to monitor their beating heart. I’ve used this crustacean heart monitor extensively on shore, but this will be my first experience bringing it to sea. There was a certain amount of arts-and-crafts involved in modifying it for shipboard work—as is often the case when building new equipment. In this case, I stocked up on plumber’s gasketing, quick-dry epoxy, and a picnic cooler to house the whole setup. (Plastic coolers are great for science—sturdy and insulated and easy to modify. I prefer the thin, 24-can versions for running cardiac experiments, while your standard beach-going Igloo cooler is ideal for holding dozens of crabs for weeks in a controlled environment.)
While monitoring crab heartbeats, I’ll slowly increase the temperature of the water in their picnic cooler to see how they respond. Periodically, I’ll collect some crabs for future work on their transcriptomes, a type of genomic sequencing lets me see what genes they’re using at a particular time and how these genes change with changes in temperature. Coupled with the heart rate data, this should give me a better understanding of how these animals perform their thermal quick-change at undersea vents.
Vent samples are rare and precious, collected, as they are, by Alvin, so mine will serve double- or triple-duty. I’ll get heart rate data and gene expression in response to heat, my main research goal. But I’ll also carefully dissect these crabs, and any other vent crustaceans I’m able to collect, saving tissue samples for additional and to search for parasites. I’ve seen estimates that more than half the multicellular species on earth are parasitic, but so far only a smattering have been described from vent animals.
As with so many other aspects of vent science, every opportunity to collect more data is useful. I’ll just make sure the Alvin pilots take care around angry crabs.
Post by: Elizabeth Trembath-Reichert, Woods Hole Oceanographic Institution/ Arizona State University
Friends on shore have been asking me, “How many people are on the ship with you?” Well the answer is 56: there are 22 members of the crew, 20 scientists, two Shipboard Scientific Services Group (SSSG) technicians, and seven Alvin human-occupied vehicle (HOV) and five Sentry autonomous underwater vehicle (AUV) team members.
Being a part of the collaborative effort this team brings to the mission of doing great science and exploring our oceans and what lies beneath them is one of my favorite parts of being at sea. Below I narrate a bit of “a day in the life aboard the Research Vessel (R/V) Atlantis as co-Chief Scientist preparing for our four Early Career Chief Scientist Training Cruise dives with daily Alvin, Sentry, and CTD operations. You will see everyone on the ship mentioned at least once.
I begin my day peeking out of the black-out curtains of my bunk to confirm it is indeed daytime. I hop out of bed, put on my sea clothes (gym shorts, a t-shirt, and fleece jacket) and head down two decks to the galley to snag easily transportable carbs from breakfast and a cup of coffee. I say Hi to Mark, the cook, who is already busy planning lunch, and make a fresh pot of coffee so that Captain Al doesn’t have to wait around for another pot to brew and can get back to the job of keeping us all safe.
Then I head down one more deck to the main science lab to check in with what has happened while I was sleeping. I see geologists Bobbi, Molly, Mike, Matt, and Valentina happily crushing and examining their rocks recovered from the first four seamount dives of our eight-dive cruise. Mel and Alex, our resident artists, are doing photo shoots of the most glamorous samples.
Microbiologist Heather is refining her microbe traps that we’ll leave on the seafloor until another cruise comes to pick them up next year. Biologist Santiago and microbiologists Rika and Karthik are briefly checking in with the their students and classes, whose final exams are happening while we are at sea. Geophysicists Ross and Aida and Ian from the Sentry team are going through maps to determine the next best Sentry track for tonight.
Todd, the Alvin expedition leader, and Justin, the Sentry expedition leader, both circle through the main lab to check with Dan, the Chief Scientist of the OASIS leg of our cruise, to verify the plan of the day.
I step out into the hallway to cross into the lab inhabited by our geochemists and biologists and see Aton, an oiler, making his rounds checking the temperatures on our ever-important walk-in fridges that allow us to keep samples at bottom seawater temperatures after they come on deck.
Once in the lab, I find biologist Carolyn looking at new specimens on the microscope and geochemists Drew, Dalton, and Alysia setting up the next round of high-temperature fluid samplers, called “majors,” scheduled to go down on Alvin tomorrow. These samplers are critical for getting and preserving the hottest vent fluids to understand the convoluted paths they take from the ocean through the rocky seafloor and back out in vents.
I walk back into the Main Lab and out to the starboard deck and try to stay out of the way of ordinary seamen Patrick and Clindor as they repair and paint spots on the deck that need a little TLC given the heavy use that R/V Atlantis sees daily.
Farther down the deck I see Sean and Manyu testing Sentry, which is back on deck after being down near the seafloor all night making high-resolution maps of where Alvin is currently operating. Farther still, I round a corner and see to the A-frame, a vitally important piece of equipment that lifts the 40,000-pound Alvin in and out of the water every day. Engineers Bobby, JT, Bill and Phil have been working on it daily while Alvin is in the water or we are transiting.
I meet Carolyn and Santiago out on the back deck to layout the ”bioboxes” we hope to use for our dives on the East Pacific Rise. They are both interested in the “charismatic macrofauna” such as the infamous tube worms and crabs that inhabit the hydrothermal vents we will visit and will need these self-sealing boxes to safely bring up creatures from the deep.
I pop up to the bridge with my co-chief Ross to confirm with the third mate Amy on watch what might be a good time to set up an informal science briefing for any interested ship personnel. We swing by the Top Lab to see if the folks down on the seafloor have seen anything interesting so far with the report they are giving every 30 minutes to pilot Mike, who is standing watch as the Surface Controller today.
Is it lunch time? I think its lunch time. We head up to the mess deck to see what Liz, the Steward) and Mark, have in store for us. I step aside to let oiler Corey and wiper Ryan go first since they are going on-shift. After shuffling through the line and doing my best to load up on veggies and fruit before I get to the cookies at the end, I sit down and catch up with where we are in the day and chat with members of the other teams on board. Common topics are sea tales of past cruises and plans after we get to port.
I check my watch and realize I gotta get rid of my tray and plates so I don’t hold up mess attendant Janusz’s turn-around of dishes between meals. We head back down to the main lab to finalize dive planning for tomorrow. Because we have a lot to do on the dive and because only two scientists can go down on each dive, we get crash courses in identifying samples that different teams need, such as biology for geologists and geology for biologists.
All of a sudden, it’s time for the end-of-day science report up in the Top Lab aft of the bridge. Alvin Electrical Lead, Drew, and all-round technician, Rick, patch us down to the sub 2,000 meters below the ship and we get a briefing of what the scientists on today’s dive saw and collected so we can be ready to process samples as quickly and efficiently as possible once they are on deck. The observers, scientists that go down in the sub, are highly complementary of Alvin pilot Jefferson’s care in collecting samples and keeping their precious rocks intact.
Then we scurry back down four decks to our labs to get ready for Alvin’s arrival before going out to watch the sub come back. Meanwhile, the crew is similarly preparing. Ronnie the bosun, who is in charge of directing all the operations on deck, takes in the scene and looks for any potential hazards as the “Alvin swimmers”—communications electronics tech Josh and Alvin tech Nick— don their swimsuits and prepare to jump into the Alvin support boat with able-bodied seaman (AB) Patrick, as AB Jim operates the crane lowering them into the water.
They zoom out to anticipated surfacing location and prepare connect lines to Alvin from the ship and catch a ride back on Alvin once it is on the surface. Meanwhile SSSG technician Allison is preparing to move the A-frame out to collect Alvin. After the sub is safely on deck, the day’s launch coordinator, Danik, directs the biologists and microbiologists waiting in the wings with their hard hats and safety vests it is now safe to get their precious organisms out of the tropical heat and into the cold room near their lab.
Then Alvin goes through its end-of-dive procedure and the observers and pilots emerge victorious from the “ball” to tell tales of what the seafloor had in store for them that day, which always begins with a description of the bioluminescence twinkling outside their windows in the otherwise pitch-black ocean on the way down, and maybe includes a tip that a visit PJ, the chief mate, to get some Dramamine for the bob along the surface during recovery, might not be a bad idea.
Once Alvin is safely secured back in its hanger we can grab the rest of the samples and head to dinner. Meanwhile the Sentry team is preparing for launch so we can maximize bottom time and get as much of the seafloor mapped as possible before Alvin goes down for his next dive tomorrow morning.
After dinner, all stations go into sample processing mode. In the main lab, fluids are filtering and cameras are displaying that day’s video. In the wet lab rocks are being catalogued. In the bio lab alien (to us) creatures from the deep sea are on display as geochemists probe their equally alien fluid compositions. At the same time, those who just dove and those who are about the dive the next day have a meeting with members of the Alvin team.
As Alvin sample processing comes to a close Karthik and Dalton prepare for the night’s CTD casts, working with the bridge and AB Molly, who is operating the winch that lowers the rosette of bottles into the water. Sentry night operator Laura is on watch to make sure the AUV and the CTD stay well away from each other. We use the CTD to send bottles down to the bottom of the seafloor and remotely trigger them from the ship to snap shut at any depth on the way back up. This is allowing our geochemistry and microbiology team to get much higher volumes of water above our hydrothermal vent plumes than we can bring back on Alvin alone. I stay up coloring some souvenir Styrofoam cups to shrink on the next day’s dive while waiting to help them deploy the CTD under the direction of the night shift SSSG, Emily.
After deployment around midnight, I scope out the reports compiled by second mate Max, who is tracking any potential weather we might have to watch out for weeks in advance, and then close my laptop. I say good night to the CTD team who will be up through the night collecting as much water as they can before Sentry needs to come on deck for Alvin to go back down.
As I swing through the mess on my way up to my bunk, oiler Anthony says good morning to me as his day is starting and I say good night as mine is ending.
Post by Ross Parnell-Turner, Scripps Institution of Oceanography
My typical morning routine involves a rushed bite of toast and slurp of coffee, then sitting in endless traffic while thinking about the possible benefits of missing that 9:00 a.m. meeting and scanning the radio to find a station that isn’t trying to sell me something. After about an hour, I arrive at my office in La Jolla, Calif., which is filled with the usual decor of desk, computer, chair, phone and a bunch of disorganized books and papers. I suspect this may be an all-too familiar routine to many of you.
Tomorrow, my commute is going to be very different: Instead of my ageing but trusty station wagon, I’ll be climbing into a 20-ton submarine called Alvin, bristling with lights, cameras and scientific equipment, that will take me two miles beneath the ocean. For one day, the seafloor will become my office and I’ll have the chance to collect precious data and samples from a place that no person has visited before.
I’m a marine geophysicist studying how the oceans are formed, and for the first time I’ll be coming face-to-face with the rocks that I’ve been thinking about since high school. As you can imagine, I’m pretty excited!
The oceans cover roughly 70 percent of Earth’s surface, and new seafloor is being created all the time. This process happens where tectonic plates spread apart at around four inches (11 centimeters) per year—about the same rate that your fingernails grow. This giant engine is driven by heat, and Earth is giving off 46 trillion joules per second, equivalent to about 46 billion household toasters. My research is focused on how all that heat gets transferred from the interior up to the surface, causing lava to be erupted—sometimes explosively, sometimes only a dribble—and driving the hot fluids that provide a habitat for life on the seafloor around hydrothermal vents and seeps.
Because it’s so difficult to actually see what’s happening on the seafloor, scientists usually have to rely on data from satellites and ships to piece together the details. By swapping my old Volvo for Alvin tomorrow, I’m going to be able to actually see the rocks on the seafloor that were formed relatively recently and by a range of different processes.
We’ll be collecting rock samples so that we can understand their chemistry, and recording video to document the lava forms we see that tell us what type of eruptions have happened in the last few million years. In addition, we’ll be collecting sea creatures (using a giant vacuum called a slurp), water samples, and sediment samples that our team-members back on board Atlantis are relying on us to bring back from this dive.
I’m also the co-Chief scientist for the Early Career Scientist portion of the expedition next week, so I’ve been spending much of the cruise planning dives by Alvin and Sentry and getting organized to help us all meet our different objectives.
We’ve been working around the clock to ensure that we’re making the most of this amazing opportunity, and it’s going to be a little strange to be actually climbing into Alvin and heading down to the seabed for the first time. I suspect that this is going to be my best-ever “day at the office,” and one that I’ll think about for months while stuck in traffic.
Post by: Dalton Hardisty, Michigan State University
Why am I here? This is a question any oceanographer may find themselves thinking during a research expedition at sea. Days from land and working around the clock, rain or shine, where uncertainty of success, waves of thrill, and simply feeling out of whack (sea sickness?) are part of the routine. “Why am I here?” is also the most important question any researcher should ask well before the work starts, and certainly before the ship leaves port.
A research expedition is typically preceded by months to years of preparation—funding, experimental methods, training, etc. In my case, this will be followed by additional months to years of follow-up work in the lab before I see the results of shipboard experiments.
Ultimately, understanding why we are here is at the core of why I am on the ship. My research is directly focused on understanding the chemistry of the oceans on early Earth and, more specifically, how oxygen produced by photosynthetic organisms shaped that world into the landscape we know today. The hydrothermal vents of the East Pacific Rise provide an amazing opportunity to better understand how the geologic record of oxygen in the ocean relates to the history of life on Earth. Hydrothermal vents are one of the many environments that may have hosted Earth’s first life, and that we also know had a very different impact on ocean chemistry in Earth’s ancient past compared to today.
This is evident to anyone from Michigan, my recently adopted home state, which hosts some the largest records of ancient hydrothermal activity—the banded iron formations in the Upper Peninsula. These and other geologic records uncommonly found in today’s oxic ocean, but prevalent in the past, are a testament to the persistence of low-oxygen conditions in the oceans for billions of years of Earth history. This permitted the widespread accumulation of oxygen-sensitive chemicals like iron on the seafloor.
In my work, the abundance of these oxygen-sensitive elements in the vent fluids and the reactions that occur upon exposure to our oxygen-rich ocean will provide a window into changes that occurred on our planet nearly 2.4 billion years ago during the Great Oxidation Event, when evidence shows that low-oxygen conditions in the ocean began to disappear.
The Early Career Scientist Cruise provides an incredible opportunity to learn the details of planning and implementing oceanographic research from a legendary group of senior scientists and to gain new collaborations with a group of eager, interdisciplinary scientists. My research objectives include evaluations of the chemistry in the vent plumes and relies heavily on the use of the human-occupied vehicle (HOV) Alvin and Nisken bottles lowered from the research vessel Atlantis itself for sample collection.
As we approach our sampling sites and finalize our scientific and logistical plans, I can feel the excitement and realization rising: This is actually happening! The chance to work onboard the R/V Atlantis and visit the almost alien world of the seafloor and hydrothermal vents via HOV Alvin is like a dream come true, one that merges my love for geology and my childhood (and adult) dreams of expeditions and discovery. I both can and can’t wait to report home on our findings and to see what new breakthroughs will arise from this amazing opportunity.
Let’s start with some numbers. Consider the number 10-7 (0.0000001). That’s the approximate length, in meters, of a single virus. Just for scale, more than 5,000 viruses could fit across the width of your fingernail. We can’t see that with the naked eye.
Now consider the number 10 million (10,000,000,000). That’s the number of viruses in a single teaspoon of seawater. Another number: there are 1023 (that’s a one followed by 23 zeroes or 100,000,000,000,000,000,000,000) teaspoons of water in our oceans. That means there are about 1030 viruses in our oceans.
To give you a sense of the sheer size of that number, if you were to line up all those viruses end-to-end, stretching out into a thin, delicate strand, that strand would span the Milky Way galaxy 100 times. (See here for citations for these numbers!)
Most of these viruses can’t make us sick—instead, their victims of choice are mostly single-celled microbes, which merely number in the millions in a single teaspoon of seawater. I study the viruses that live in the darkest, hottest places in our oceans—deep-sea hydrothermal vents. Not only do viruses live in hydrothermal vents, but we think those viruses manipulate microbes by hiding in their genomes.
One of the best-known examples of viral manipulation of a host microbe occurs with the disease cholera. This disease is caused by drinking water contaminated with the bacterium Vibrio cholerae, and can lead to severe vomiting and diarrhea or even death. However, the symptoms of cholera are not caused by the bacterium, but by a portion of a viral genome tucked inside the genome of Vibrio cholerae. It is this viral genome that carries a gene encoding a toxin that causes the symptoms of cholera.
Some viruses are beneficial, often in surprising ways. Millions of years ago, a virus infected a mammalian ancestor, delivering a gene that allowed it to form a placenta. Without a virus, you wouldn’t have been born. (See here for more info on that story.)
Viruses similar to the cholera virus reside inside the genomes of hydrothermal vent microbes, as well. I want to know whether they carry genes encoding toxins or if they carry other types of genes.
My goal on this cruise is to collect viruses and microbes from deep-sea hydrothermal vents and then peer into their genomes to find out what kinds of viruses are there, who infects whom, and what genes the viruses carry. In the past, we’ve seen evidence of some viruses enabling their microbial hosts to obtain energy from different chemicals within the hydrothermal vent fluid than they usually do. This gives the microbes an additional tool in their genetic toolkit that helps them survive when the need arises.
We usually think of viruses as parasites in that the virus gets some benefit out of the relationship, but not the host. But if a virus is hiding inside a microbe, then helping the microbe also helps the virus by ensuring that it has a safe place to live. In cases like this, viruses can become beneficial symbionts—at least for a while. Eventually, that virus will eventually leave its safe haven. It will start making new viruses and then burst the host microbe open to go off in search of new victims.
Viruses are messing around with the genomes of their hosts in just about any environment on Earth, but I’m interested in deep-sea hydrothermal vents because I think viruses have been playing this game for billions of years. Some scientists think that deep-sea hydrothermal vents were important sites for the origin and early evolution of life on Earth, and I think this virus-host relationship was key to that success. If we can understand how evolution operates in these places, we might better understand how microbes and viruses evolved together on the early Earth—and whether life might exist elsewhere in the universe.
How does a research expedition begin? With the submission of the proposal? With its acceptance? With the first meeting of the team? When everyone arrives on the ship? Or when the ship finally casts off?
There are many beginnings to something as complicated as this. We have passed many of them and are now making final preparations on the ship before we leave Manzanillo at 8:00 a.m. Monday, December 3. I almost wrote, “And then the real work begins,” but in reality, this team has been hard at work planning and organizing for months, if not years.
And that, perhaps, is the first and most important lesson for the early-career scientists on board Atlantis—that a complicated, multi-disciplinary expedition like this, one that involves a limited number of dives by the submersible Alvin and autonomous underwater vehicle Sentry in several locations spread over hundreds of miles, is only going to succeed with careful, detailed planning and organization.
We’ll get to all of that in future posts. First, a road map of the next two weeks:
This expedition will unfold in two parts. When we leave port Monday morning, we’ll head first to a chain of seamounts south of Manzanillo and west of the East Pacific Rise at 8°20’ N to complete the 2016 OASIS expedition with four Alvin and three Sentry dives. After that, we steam 100 miles north to the East Pacific Rise at 9°50’ N to do four more dives with Alvin and Sentry. The latter part is official the Early-Career Scientist (ECS) portion of the expedition, but in fact, the entire trip is a learning experience.
Today (Sunday) was our first full day on the ship and we spent transforming it to meet our needs—which are very different from those of the previous science party. Fortunately, Atlantis, like all the ships in the UNOLS fleet, is built to be flexible and we gradually reconfigured the lab spaces into a shape that will permit microbiologists to work alongside geologists and fluid chemists to share space with macro biologists. Meetings were also a big part of our day, including a quick tutorial from WHOI geologist Dan Fornari on the nuances of arranging the equipment and sample containers on the science basket mounted to the front of Alvin.
Tonight, we’ll finish securing all of our gear for sea by tying down computers and monitors and strap and We’ll continue preparing as we transit from Manzanillo to our first dive site on Thursday morning. Keep following along to learn more about what we’re doing and to hear from each of the early-career scientists on board. You can also keep up with us on the UNOLS Chief Scientist Training Facebook page (@UNOLSCSW) or by following the hashtag #ECS2018 on Twitter or Instagram.