Atlantis, the Floating Lab

At 6:00 a.m. on Saturday, January 28, Atlantis reached Port Everglades in Ft. Lauderdale, Florida. The science team is certainly ready and excited to be on land, and I don’t blame them. They have been working around the clock for the last three weeks with no breaks. And when I mean around the clock, I literally mean around the clock. When Jason or a CTD is in the water, two or three team members must be on watch, and many more must be up for the recovery of samples. Sometimes Jason is in the water for more than 24 hours, and watch shifts are partitioned in four-hour shifts among the science team.

Red rock from the seafloor

As mentioned in the last post, the Geology Team has the important job of categorizing the rocks found at both vent sites to understand how hydrothermal vents alter the seafloor landscape and how they chemically interact with the hot vent fluids. Although rocks may seem like solid, unchanging objects, they are still chemically active even if it isn’t in obvious ways. The easiest example to think of is iron. Ever see a red-colored rock? It probably had some iron in it that has reacted with oxygen to produce iron oxide—rust. The same has happened to a red rock taken from the seafloor; the iron in it has reacted with dissolved oxygen in the water.

In the Proterozoic Era (3.1 to2 billion years ago), before oxygen was abundant in Earth’s atmosphere, single-celled, ocean-dwelling cyanobacteria began releasing oxygen as a waste product. As this happened, it is thought the oxygen reacted with any iron that was around, and there was plenty in the oceans. It did this in cycles of high and low oxygen concentrations and iron-rich sediment was deposited on the seafloor over time. After millions of years, these sediments hardened into sedimentary, forming sedimentary rocks called banded iron formations, or BIFs. BIFs are  important economically speaking, as this is where most of our iron ore comes from.

Rocks react with seawater on the seafloor and they also react with the mineral-rich hydrothermal fluids. As hot water passes through seafloor rocks before exiting a vent, it will dissolve minerals in the rocks. The Fluids Team is measuring chemicals in the fluids coming out of the vents in order to piece together a bigger picture of the rocks below the vents based on the minerals and gases they will be measuring.  

The Fluids Team:  Getting into hot water

Jeff Seewald

Dr. Jeff Seewald, who has been working on vent fluids for over a decade, and his team from WHOI (Jill McDermott and Sean Sylva) are taking on the task of analyzing the chemicals in vent fluids. Eoghan Reeves from the University of Bremin and Freider Klien from WHOI are also associated with the Fluids Team.

In order to be effective chemical detectives the team uses specialized equipment able to sample vent fluids and, as they are brought to the surface, keep them at the very high pressures in which they were collected—over 240 times the atmospheric pressure at sea level. The gas-tight samplers are critical if they are to analyze dissolved gases in the fluids, which would escape from solution as the pressure dropped. Jill will be looking at the major gas chemistry of the fluids—CO2, methane, hydrogen sulfide, carbon monoxide, as well as others. They’ve already been measuring some of these on the ship.

As cold seawater sinks through cracks in the seafloor it dissolves minerals in the rock before emerging as enriched vent fluid. By looking at the chemistry of the fluids, the Fluids Team will be able to give a better idea of what kind of rocks the fluids interacted with. “Vent fluids are the window into the sub-surface processes that transform sea water because its hard to see what’s below the sea floor and technically very difficult to drill in ocean ridges,” said Jill.

Jill McDermott

Because these sites sit on old, mafic (silicate minerals with high magnesium and iron content) rocks, the resulting fluid chemistry is different than vents at other spreading centers and could be analogous to conditions present on early Earth.

The vent fluids are also what sustain these unique vent ecosystems, so it’s critical to understand what minerals, or nutrients, are available and to connect them with the life that is consuming them. So far the team has found unusually high concentrations of hydrogen, a great source of energy for microbes. “Ideally we like to link the chemistry with the biology conditions in what supports life—Julie [Huber] will be interested in the chemistry in the areas where she was collecting microbes, “said Jeff, which brings us to our next group the Microbiology Team.  

Microbiology Team: Looking out for the little guys

Microbial samples

Julie Huber, from WHOI’s Marine Biological Lab, and her research assistant Emily Reddington are studying seafloor microbiology. Hydrothermal vents make excellent homes for microbes as they exploit the complex chemistry of the fluids, consuming mainly methane, hydrogen, and sulfur compounds. The Microbiology Team collected samples of microbial mats near vent sites as well as microbes that live in the fluids themselves. The team brought special ovens on board so they could attempt to culture the microbes, as these critters like to live at high temperatures. In addition, some of their samples were frozen and shipped back to Julie’s lab for molecular analysis. “Once we get back to the lab, we can extract DNA and ask who is there and what genes are they carrying,” said Julie.  

Carbon Team: Heavy thoughts

Last, but certainly not least, are Max Coleman and Sarah Bennett, scientists from the NASA Jet Propulsion Lab that make up the Carbon Team. Max and Sarah are actually members of all the teams, and with good reason. They have been working with the Plume Team, the Biology Team, the Geology Team, the Fluids Team and the Microbiology Team to collect samples from every area on the vent systems here are the Mid-Cayman Rise. They are looking at the bigger picture to get a better sense of how the element carbon is altered as it passes through the vent system.

Max Coleman and Sarah Bennett

Taking a step back, carbon forms the backbone for ALL life on Earth and it comes in a few different forms or isotopes (number of neutrons in the atom). Roughly 99 percent of all carbon exists in its most stable (and lightest) form, carbon-12, which has six protons and six neutrons. Roughly 1 percent exists as the heavier carbon-13, which has seven neutrons, and a very small fraction is carbon-14, which is radioactive. When organisms consume carbon, it’s much easier for them to make use of the lighter isotope, carbon-12, than the heavier. Think of going backpacking—it’s much easier to carry around a lighter pack than a heavier one.

Even though carbon-12 is way more abundant than carbon-13, organisms will still take up a very small amount of carbon-13 and this can be detected through careful analysis. Larger animals that feed off of the microbes, will likewise be consuming the already carbon-light microbes, and so on up the food chain. Sarah and Max will be studying the ratios of carbon-12 to carbon-13 from the amount present in the rocks on the seafloor, to the amount in the vent chimney and the vent fluids, to the microbes and macrofauna, in the plume at various depths, and all the way up to the surface. They even collected a flying fish that found its way on deck!

Their work will also show how carbon is altered by life, which will be valuable when considering where and how to look for life on other planetary bodies. If we know how and how much the carbon signature is altered by living things, scientists will have a better grasp for discerning how the observed environment has been altered due to the presence of life.

Signing Off!

The OASES 2012: Return the Mid-Cayman Rise has come to a close and everyone is making their way back home. However, the science doesn’t stop here. The following weeks and months the teams will be analyzing their samples, some under microscopes, some in machines called gas-chromatographs, some even doused in x-rays at synchrotron radiation facilities. Eventually, these teams will write their results in papers and present them at conferences. So keep a look out for future news of the various results from this expedition.

It has been my pleasure communicating the very interesting science on board Atlantis. Not only did I learn a lot, I had an excellent experience during my first time at sea. I would like to thank everyone on the science team, the Jason team, and the crew for making this cruise such a memorable experience. This will be my last blog post and it has truly been an honor.

This is Julia DeMarines, signing off. 

Goodbye Jason, Hello Geology Team!

Jason Takes a Bow on the Stern

Jason returns for the last time.

Jason has just surfaced from its last dive of the cruise to a warm welcome from a group of scientists hungry for their samples. The vehicle has completed ten nearly flawless dives, with one minor glitch during which its manipulator arms stopped responding mid-dive. Luckily, Jason has a hardworking crew available around the clock to make sure it functions properly. They fixed the arms and all is good, although many are tired. 

The Plume Team launched one last, eight-hour CTD cast to get a background, or control, sample of ocean water far away from the mineral rich plumes. Using this, team members can study how different their plume samples are from the norm. Immediately after the CTD surfaced, the Plume Team removed their samples and sampling instruments and Atlantis began to head back to port. It will be a two-and-half-day journey, and everyone is in good spirits. 

Chris explains the dive plan to Matt.

On Jason’s last dive, it investigated some unexplored mounds on its way to the Von Damm site. During this exploration dive, it picked up several rocks that looked interesting. This was an exciting time for the Geology Team, whose members are always thirsty for samples. In the ROV Van, the geologists noticed an outcrop of rock close to the Von Damm site they wanted to sample. After an hour trying, Jason’s incredibly strong robotic arms could not break off a piece of what we quickly dubbed ‘kryptonite’. 

In addition to rock sampling, there were also important vent biology and fluid samples to be collected on our last dive, so around 10:00 p.m., Chris called off the attack on the rock and directed the Jason Team to make sure they completed everything else on their list. By 4:00 a.m., Frieder, Max, and Chris were back in the van, but there were still two vent-fluid samples to collect from the top of the Von Damm mound before the geologists could get back to it.

At 6:00 a.m. and with time running out, Jason moved off to the north of the Von Damm hydrothermal mound in the direction of the krypotinite outcrop to see if there might be more outcrops of the same material. Sure enough, a near-identical outcrop appeared, and Jason’s pilot tried valiantly once more to break off a sample, again without success. 

Happy geologist (Frieder) with basalt.

Another 30 minutes had elapsed and we only had half an hour left. With not much time left on the clock, the geologists decided it was time to take a gamble and requested that Jason continue on further in the same direction. With fifteen minutes to go, the team found a third outcrop of similar rocks that had evidence of slightly more weathering than the previous ones and, at just three minutes after the hour when their time was up, they were finally able to collect a piece. In this case, the third time was indeed a charm. When the team got their sample back on deck, it turned out the rock wasn’t kryptonite at all, just a very (VERY) tough basalt.

Geology Takes Center Stage

The Geology Team is an international group composed of three members: Guy Evans and Frieder Klein from WHOI and Matt Hodgkinson from the University of Southampton in the U.K. They have the important job of analyzing rocks plucked from the seafloor, and their work will help tell the tale of the water-rock processes that go on beneath the seafloor at these vent sites. In addition expanding geologic knowledge , their research could have applications to both mining and the field of astrobiology. 

Beebe vents 1-4

Let’s take a step back and recall how deep-sea hydrothermal vents are formed. Hydrothermal vents form when cold seawater seeps into the crust through cracks in the seafloor. In places where water meets very hot rocks, as happens in places like Yellowstone or along spreading centers like this one, the water becomes acidic, dissolves minerals from the rock, and is enriched in metals (iron, zinc, copper, etc.). Ultimately the hot, enriched water rises buoyantly through cracks, or faults, and meets the very cold ocean water. At the moment it does, the minerals in the fluid precipitate out as tiny, solid particulates. This is why the fluids coming out of the black smokers look, well, like black smoke. Over time, these sulfur-rich minerals accumulate to create the bizarre chimneys we see around vent sites. 

As mentioned, the Geology Team’s research is potentially important in the mining world, as well. On land, copper, zinc, and other metals are readily available at what geologists call inactive volcanogenic sulfide-mineral deposits. The processes that form these land deposits are analogous to those that form deep-sea hydrothermal vents. At inactive sites on land, geologists can’t sample the mineral rich fluids responsible for creating the deposits, and this hinders their ability to answer some very fundamental questions.

Geology Team (l-r): Frieder, Guy, and Matt

“Since they are not active, it’s difficult to know how they were formed,” said Guy.  “What we’re hoping to do is determine certain characteristics to make connections from active sites to inactive sites”. This information could help the mining industry determine locations to mine in the future.

Frieder is most interested in understanding what controls the fluid chemistry and the fluid-rock interactions in general, and is also working closely with the Fluids Team (who I’ll describe in a later post) on these and some much larger questions. “I’m trying to understand how fluids react with rocks and how this influences the chemistry of the oceans,” said Frieder.

From the information he gathers, the team can determine the temperature at which these reactions occurred and learn more about the environmental conditions beneath the seafloor when they were altered. This is important when considering the larger picture of life in the universe, as many astrobiologists believe hydrothermal systems possess the right conditions to have kick-started life on Earth. “There are some conditions you need to understand when thinking about the origin of life," said Freider.  "The key components are pH, hydrogen concentration, methane, CO2, and temperature, which we try to constrain using the rock record.”

As mentioned in a previous post, this site is of particular interest because of the atypical spreading of the seafloor. New seafloor isn’t being freshly deposited by volcanic activity such as along the Mid-Atlantic Ridge, but rather the tectonic plate is actually being dragged up, stretching the seafloor and exposing old mantle rock. The Geology Team was hoping to collect samples of mantle rocks, proving this theory, but was stymied. “We haven’t found any rocks with mantle origin, and we’re not to sure why that is,” said Matt. “Probably it’s because they’re covered in sediment.” 

Matt is also going to look at the radioactive isotope radium-226 and its decay product, barium, to pin down the ages of the chimneys at the two vent sites as well as the overall age of the system. In addition, he’ll be looking at a process known as secondary enrichment, which often results in an increase of concentrations of copper and zinc concentrations in the mound after it forms.

Thinking cosmically, studying the geology at hydrothermal sea vents may yield clues to hydrothermal interactions on other celestial bodies and may help us home in on interesting places to look for life. Hydrothermally altered mantle rocks, which we hoped to find at the Von Damm site, have been described on the dwarf planet Ceres and on Mars. By studying these rocks in situ on the seafloor scientists can learn more about possible fluid-rock interactions on extraterrestrial bodies, which are understandably difficult to examine. This opens doors to astrobiologists who are interested in studying extraterrestrial conditions similar to the ones present at the origin of life on Earth.

Introducing: The Bio Team

One of the most exciting parts of this cruise has been seeing what lives in these depths and bringing sample organisms back to the surface to study them in greater detail. This is the first time that a significant amount of biology has been brought up from this site.

Bio Team at work

The Bio Team on board is dedicated to the study of macrofauna (large animals) on this expedition and includes five people: the principle investigator, Cindy Van Dover from Duke University, her post doc Sophie Plouviez, and grad student Jameson Clarke, as well as Paul Tyler from the University of Southampton and his grad student, Verity Nye.

Several others are also involved with the Bio Team’s work and together they have collected many samples to distribute to different labs once we return to port. The team instructs Jason’s pilot which animals to sample using the vehicle’s manipulator arms. The pilot then places the samples in the biobox on the front of the vehicle and closes the lid before surfacing. Smaller animals such as shrimp he collects with a device aptly named the “slurp,” which sucks up anything near its nozzle, much like a vacuum cleaner.

After every Jason dive, the team forms an assembly line, where they take an inventory of their samples, image them, and slice up pieces of the animals to be used for genetic study later. Verity Nye described the process: “First we preserve the whole animal in formalin to take it back to our lab. We look at the whole animal very closely to see if it is something already described or if it’s something new to science.”

Tubeworm out of its tube. The black part is
full of symbiotic bacteria that feed the worm.

Vent sites have very unique biodiversity. At the bottom of the food chain are the microbes. They are mainly chemosynthetic bacteria able to make a living off of the chemical-rich fluids coming out of the vent. These bacteria sustain larger animals in a symbiotic relationship. The bacteria thrive on vent fluids, even if they live inside the gut of a tubeworm or on a shrimp. This is why the symbionts (animals that depend on another organism to survive) live in such close proximity to vents or seeps—so the larger host animals can keep their microbes healthy. In return, they get a full belly of nutrients. Otherwise, the larger animals wouldn’t be able to survive here.

The Bio Team is mainly concerned with sampling macrofauna at the two main hydrothermal vent fields: Von Damm (2300 meters deep) and Piccard (5000 meters deep). The team will be analyzing, categorizing, and prepping the samples for phylogenetic studies in their respective labs.

So far the Jason Team has brought back incredible samples from the depths that are a real treat to look at. These include three species of shrimp, two species of tubeworms, star fish, sea cucumbers, coral, mussels, clams, sea anemones, squat lobsters, gastropods (snails) and even some fish.
Following the InterRidge code of conduct, this team is choosing to sample only a small fraction of the total number of each species present at the seafloor in order to minimize any impact on the populations they find there.


A Mystery Lurks Below

These active hydrothermal sites on the Mid-Cayman Rise are unique and especially important to study because of the recent discovery of tubeworms and shrimp here. If you aren’t an avid vent fauna researcher or enthusiast then you might miss the significance of these two species being found together (as I did). I learned that tubeworms are seen in the Pacific vent sites and at cold seeps in the Gulf of Mexico, while shrimp are only found in the Atlantic. Shrimp and tubeworms have never been seen together at vents until Chris German and Paul Tyler first dived at these sites using the Little Hercules ROV aboard the NOAA ship Okeanos Explorer in August 2011.

Tubeworms

This raises several questions regarding the origin of the tubeworms. From where did they migrate? Are they related to the tubeworms found at cold seeps in the Gulf of Mexico or the Pacific Ocean? If they resemble Pacific tubeworm species, then how and when did the first tubeworm larvae make it to the Caribbean? Did their predecessors arrive via the Panama Canal or before the North and South American landmasses joined together about three million years ago? “It is not well known how far tube worm larvae can travel,” said Plouviez.

These are questions that the bio team hopes to answer through detailed studied morphologic (physical differences) and phylogenetic (molecular differences) of these tubeworms. 

Cindy and Jameson

Cindy’s grad student, Jameson Clarke, is interested in linking the genetic information of the biology at these vents with similar information about species in other geographic locations. As Jameson told me, his main interest on this cruise is to investigate the genetic connectivity and biogeographic relationship between the sites to study the extent to which the sites are exchanging genetic information. They also aim to know where tubeworm sites have been colonized through evolutionary time. This may shed light on how ocean currents and ocean nutrient cycling plays a roll in the migration of isolated species, not just at vent sites, but globally, as well.

Shrimp!

Another exciting moment for the Bio Team was the identification of three different species of shrimp. At the shallower Von Damm site, the shrimp are much larger than their cousins at the deeper Piccard site. The discovery of three different species is especially exciting for Cindy, as she’s had a long history of studying the biology of vent sites since vents were first discovered. In 2002, Cindy published a paper grouping similar biologic life at different vent regions (indicated by dots of the same color on the map, left). After an in-depth study of the biology at this site, she hopes to understand which regions share similarities to the Cayman site. 

Shrimp with eggs.

Paul and Verity, from the University of Southampton, are interested in how and when vent species reproduce. For Paul, the most interesting thing about the cruise so far has been finding female shrimp carrying eggs. He explained that the last time shrimp were sampled was during the summer months at the Mid-Atlantic ridge, few if any of the shrimp carried eggs. Perhaps information form these shrimp will help determine if there is a seasonal periodicity of reproduction. As Paul put it, “reproduction maintains population, it gives opportunities for vent species to colonize new vents.”

How the tiny larvae of vent fauna locate and populate vents in the vastness of the deep ocean remains one of the important questions in vent biology Research like that of the Bio Team will contribute towards finding these answers. This expedition so far has been a truly rich experience for all of the teams.

“One of the things I love about this project is the teams of scientists, and the bigger picture of life in the oceans,” said Cindy. “There have been very interesting conversations. It’s like being at summer camp for scientists.”

InterRidge

It has been said that one of the biggest threats to hydrothermal vent ecosystems are the scientists who research them. After all, we do collect wildlife samples, break off pieces of vent chimneys and scoop up rocks, which are all technically habitats down there. But is it so bad if all this is done in the name of science? Well, yes and no, but there are ways to be responsible about advancing the sphere of knowledge without being overly destructive.

To help guide research on and around hydrothermal systems, an international non-profit organization called InterRidge provides a set of guidelines and policies outlining responsible research practices designed to minimize destruction and maximize scientific output from studies of hydrothermal vent environments. InterRidge, which has nearly 2,600 members from more than 60 countries, exists to promote interdisciplinary, international studies of oceanic spreading centers by creating a global research community where technology and scientific information can be exchanged. These guidelines instruct us and anyone who might be carrying out such studies to do the following:

1) Avoid, in the conduct of scientific research, activities that will have deleterious impacts on the sustainability of populations of hydrothermal vent organisms.
2) Avoid, in the conduct of scientific research, activities that lead to long lasting and significant alteration and/or visual degradation of vent sites.
3) Avoid collections that are not essential to the conduct of scientific research.
4) Avoid, in the conduct of scientific research, transplanting biota or geological material between sites.
5) Familiarize yourself with the status of current and planned research in an area and avoid activities that will compromise experiments or observations of other researchers. Assure that your own research activities and plans are known to the rest of the international research community through InterRidge and other public domain databases
6) Facilitate the fullest possible use of all biological, chemical and geological samples collected through collaborations and cooperation amongst the global community of scientists.

This means that everything we collect on this cruise must be taken for a scientific purpose and be used to generate as much new knowledge as possible. Atlantis and her science team are proudly adhering to InterRidge's responsible research practices guidelines, and it is inspiring to watch those ideals in action in a progressive and scientifically responsible environment.

InterRidge's activities are increasingly important, as the precious metals found at hydrothermal vents have been catching the attention of the mining industry. Because these hydrothermal vent sites are pristine and fragile ecosystems, they need to be protected from excessive exploitation. As Cindy Van Dover puts it, “Most vents are found in international waters, where there is little environmental oversight of deep-sea habitats, or in the territorial seas of countries with nascent or non-existent conservation policies that apply to deep-sea hydrothermal vents.” You can read Cindy's recent article about the importance of conservation at hydrothermal sea vents here (pdf).

Eoghan Reeves

InterRidge also provides a number of student and postdoctoral fellowships that enable international researchers to collaborate and take advantage of seagoing expeditions. Eoghan Reeves, a postdoctoral fellow at the MARUM Center for Marine Environmental Sciences at the University of Bremen, Germany, was able to join this expedition because of InterRidge. “Thanks to InterRidge I have a chance to do some exploratory research with the hydrothermal plume sampling team [Chip, Brandy, Sarah and Greg], to examine if sulfur from the vent environment becomes incorporated into organic material in rising plumes,” he said.

The process Eoghan is studying could affect the delivery of metal nutrients from the vents to the ocean. Also, through his collaborations with the hydrothermal fluid sampling team (Jeff, Jill and Sean), he is able to continue his previous research on vent fluids containing methanethiol, a sulfur-containing molecule that may have had a big role in the emergence of life on Earth. Methanethiol, or methyl mercaptan, is similar to the smelly substance added to household gas for safety and Eoghan has previously found it in moderate-temperature black smokers at the Mid-Atlantic Ridge and East Pacific Rise. Researchers studying early Earth biochemistry are very interested in the compound, as it may have been crucial to the formation of the first amino acids and proteins in primordial hot springs. At Piccard and Von Damm, he now has a chance to look for it in much hotter vent fluids.

Eoghan’s measurements will help understand how methanethiol forms and what its presence means to a hydrothermal origin of life billions of years ago. “Without InterRidge, this great opportunity to work be part of the expedition would simply not have been possible,” said Eoghan.

Super Samplers

A bout of bad weather and rough seas kept Jason dry for two days until conditions improved early this morning. Even though the vehicle was at rest, the science team had plenty to do to keep busy. 

CTD cast

With seas too rough for Jason dives, the science team was still able to map the area with the ship’s multi-beam system and were still able to launch three successful CTD’s (conductivity, temperature, depth), with plenty of sampling equipment attached. 

As mentioned in a previous post, the Plume Team is interested in collecting samples of particles and chemicals from various heights above the vent. With Jason on house arrest, the Plume Team fitted their SUPR (SUspended Particle Rosette) Sampler to the CTD to collect samples from the water column. Atlantis is able to park directly above plume sites thanks to the meticulous mapping done by the Jason team. 

Vent fluid sample

Chip Breier, the lead engineer of the Plume Team’s project, designed and built all of the samplers. There are three instruments, each composed of a 14-channel sampling system and each with a different purpose: the Microbiology Sampler, the Geochemistry Sampler and the Carbon Sampler. Although each collects material in a similar fashion (sucking in fluids through a tube) three separate devices are necessary due to differences in the way each sample is analyzed. For example, to measure carbon, you must combust your sample to measure the carbon dioxide released, so you need a filter able to withstand combustion. On the other hand, you need a carbon-based filter to collect microorganisms, and a polycarbonate (plastic) filter to collect minerals for geochemical measurements. 

Sara Bennett

Sara Bennett, a post-doc at NASA’s Jet Propulsion Lab (JPL), is using a pre-combusted glass filter to measure both solid and dissolved carbon in the plume. She is interested in how carbon is cycled through vent systems and is working with Dr. Max Coleman from JPL who is also onboard. It is important to study the state of carbon as it exits the vent and how carbon is altered through the food chain. “We’re looking at the whole carbon cycle, from abiotic carbon production deep within the crust, to biotic carbon production through chemosynthesis,” said Sarah. “If hydrothermal systems were to exist on Europa, it’s studies like this that may help us to calculate the biomass that may exist” Sarah says. 

Greg Dick

Greg Dick, from the University of Michigan’s Department of Earth and Environmental Sciences Geomicrobiology Lab, is interested in the microbiology associated with vent sites. He will be analyzing the SUPR Sampler’s filters to extract DNA and RNA of these very tiny microbes. “From these samples we can reconstruct the genomes in the organisms, which will tell us what organisms are there, their physiology, how they live and how they get their energy,” said Greg. 

However, enzymes very easily destroy RNA, so the samples must be treated with an enzyme-killer called “RNA later.” It is important to understand the genetics of these microbes, but it is also important to know which genes the microbes are using to survive in these conditions. The RNA tells Greg what genes they are expressing at the moment they were collected. 

Chip optimized the third sampler out of his and Brandy Toner’s interest in the mineralogy of the vent plume and, more specifically, what valance states the minerals are in at different heights above the plume. From this, they can begin to understand how much energy is available for microbes in different parts of the plume. Brandy will take these samples to a synchrotron facility to study them with x-ray spectroscopy. “Because of the way these samples are collected, preserved and analyzed, there is very low impact,” said Brandy. 

Brandy Toner (right)

As you can imagine, the Plume Team brought on board massive amounts of lab equipment dedicated preserving each sample and minimizing exposure to the environment.  So far they’ve collected about 50 samples that are currently preserved at -70º C.

From measuring the microbiology, geochemistry, and carbon from the highest energy source (at the vent) towards the lowest (near the surface) the Plume Team hopes to gain insight of who’s eating what and where, and what that tells us about the bigger picture of life in the ocean This team has been working around the clock and all of their hard work will surely extend our sphere of knowledge about the life and chemistry of the ocean. The Gordon and Betty Moore Foundation are funding their work, and we all look forward to their results!

Underwater Lawncare and Plume Teams

Jason completed a successful third dive yesterday, which was primarily dedicated to mapping Von Damm site using the multi-beam system. Mapping is a very tedious task. The pilots controlling Jason have to drive as straight a line as possible while Jason automatically maintains an altitude of 50 meters above the seafloor terrain.

The Plume Team

They make lines 400 meters long and take measurements continuously along lines spaced at 50-meter intervals over the whole site, taking care to ensure there are no gaps. The process is like mowing a lawn—one that can take 12 hours or more finish. It is important for these sites to be thoroughly mapped, as previous maps of this area are inaccurate and at a lower resolution. In addition, the high-resolution images can reveal new, never before seen vents and can be used to create a mosaic image of the entire site.

On the tail end of the dive, a group of scientists dubbed the Plume Team (left to right: Chip Breier, Greg Dick, Sarah Bennett, and Brandy Toner) were given precious dive time to collect samples of vent fluids from different heights in the hot plume of particles and fluids that originate from the vent. The samples that the team gets are collected in a novel way, and the team has been putting in incredible hours around the clock, building their own equipment.

Jason sampling the plume

All of their hard work has paid off and their sampling equipment performed magnificently. Right now, the Plume Team’s equipment is on Jason’s fourth dive, which launched yesterday at 4:30 p.m. Another session of mapping is on Jason’s plate, but this time the vehicle will move to just 20 meters above the seabed to create more detailed maps. After the mapping is finished (around 6:00 a.m.) the Plume Team will be collecting samples again at various heights above the vents. The data that the Plume Team collects will permit them to study the different minerals and microbiology in the water, which is important for understanding biogeochemistry (the interaction between life, geology, and chemistry) in the ocean. The science that the Plume Team is interested in will be the subject of a later post, so stay tuned.

The Plume Team received support
from the Gordon and Betty Moore Foundation

In other exciting news, we spotted a waterspout around 11:00 a.m. yesterday.  






Why is the Mid-Cayman Rise so important? (Continued from previous post)

As I mentioned earlier, the Mid-Cayman Rise is a spreading center, much like the Mid-Atlantic Ridge, which is responsible for pushing the Americas apart from Africa and Europe. However, the Mid-Atlantic Ridge spreads at a rate of 25 to 35 millimeters a year (the rate that your fingernails grow), but the ultra-slow spreading center at the Mid-Cayman Rise spreads at just 12 millimeters per year. Geology reveals that rocks normally get older as one moves away from a spreading center (and active venting). Strangely, this is not entirely correct with ultra-slow spreading centers.

The slab-pull process (Wiki Commons)

There are two ways that plates are thought to spread: ridge-push and slab-pull. An example of spreading due to the ridge-push process is the mid-Atlantic ridge, where new sea floor is erupting from the mantle is pushing plates apart. It is thought the Mid-Cayman rise is spreading by the slab-pull process.

Close to spreading centers, where new sea floor is erupting and the plate is young, the tectonic plate is hot and less dense (or lighter). As you move away and get into the older, cooler sections of the plate, it gets denser (heavier). As the plate gets denser it begins to sink into the mantle, also known as subduction.

It is thought that the other end member of the Cayman plate (the old, cool, and dense part) is subducting underneath the American plate, pulling the rest of plate along with it. This still creates new sea floor, however it’s not of new crust, but of old crust (ultra mafic) being pulled out from deep underneath.

Think of the plates as stack of books that have fallen over and that the orange book is the Cayman Plate. Now imagine what happens when I drag the orange book out, which is analogous to the way the the subducting end of the plate is dragging the rest of the plate along. I am still creating more ‘orange book’ sea floor but it is not fresh. Scientists call this type of spreading amagmatic spreading (not volcanically active).

Scientists long thought that hydrothermal vents would not be present at these non-volcanic ultra-slow spreading centers because there is no fresh volcanic heat source near the seafloor. However, Dr. Chris German and others had a hunch that there might be vents there and sure enough there are! It is still unclear how exactly these vents exist here, but theories suggest that perhaps the rising plate makes becomes thinner. When the plate is thinner it is physically closer to the hot mantle below, and cracks could easily form creating a path for seawater to penetrate to depths where heat in the Earth causes it to re-circulate, creating hydrothermal activity on the surface.

First Dives a Success

Dive #1 Complete

January 9 marked Jason’s first dive of the expedition. The vehicle descended to 2300 meters to reach our first target, the Von Damm vent site, which is the shallower of the two planned locations. Shortly after reaching the seafloor, the vehicle began heading towards the vents.

Tubeworm goes under the microscope

Along the way, the science team instructed the pilot to collect samples of interest. With its two strong robotic arms, Jason was able to break off and collect several samples of rock and pieces of the vent. Jason’s arms are also dexterous enough that they gently collected five tubeworms, a clam, and a sea cucumber and placed them in a tub on the front of the vehicle called the bio box.

Because this site is so unique, energy levels in the ROV van were high. After Jason surfaced, the science team quickly retrieved their samples and began analyzing them. It was an incredible experience to be present as Jason returned with samples from the Mid-Cayman rise, home to the deepest hydrothermal vents ever discovered.


Dive #2 Underway

Jason dives to Piccard

After our success at Von Damm, Atlantis headed for the second target, the Piccard site, about an hour away. Jason's second dive went off without a hitch, beginning just after midnight. Check out the eerie color in the water as Jason began its three hour, 5000 meter journey to the deeper of the two sites.

The images from Piccard were breathtaking, with black smokers sending a whirlwind of mineral-rich fluid into the dark water. Everyone in the van was mesmerized by the images on the monitors, even if they had seen hydrothermal vents many times before.

Microbial mats

During the dive, we saw strange yelloworange and white mats—what looked like fur on rocks was actually strings of microbes! Jason also broke off a piece of the vent to bring up to the surface at around midnight tonight.  

History of the Cayman Rise 

I was curious as to why this particular site is of such scientific interest, so I sat down for an interview with Dr. Chris German, the PI (Principle Investigator) of this expedition. He filled me in on the history of exploration of the Cayman Rise and why he is so interested in studying it.

In 1976, Bob Ballard, a geologist then working at Woods Hole Oceanographic Institution, became the first person to investigate the seafloor at the Mid-Cayman Rise. The vents had not yet been discovered, and he used Alvin, the famous submersible, to explore the area. However, this ridge reaches depths of 5000 meters or more and Alvin can only reach a depth of 4500 meters. Ballard’s team also brought along Trieste, a bathyscaphe capable of diving to greater depths, which they used to reach deeper parts of the ridge. “This was the only time that anyone has been down there and seen it with their own eyes” Chris said.

However, because Trieste could only go up and down, they had to tow a camera system called ARGO over the seafloor to get the first confirmation that there were lava flows down there. “Thirty-five years later we get the first chance to come back with the latest WHOI technology and study cool new vents that were probably actively here all along.” Chris said.

Seafloor spreading (USGS)

In 1968, a man named Carl Bowin had also been involved with researching the Mid Cayman Rise. Bowin was one of the first proponents of the geologic concept of sea floor spreading (http://en.wikipedia.org/wiki/Seafloor_spreading). Chris remembered first meeting Carl Bowin. “I met him when I first moved to Woods Hole in 2005,” he said. “He introduced himself as the first person that ever took a computer to sea. It was at the time when they were still referring to plate tectonics as being ‘just a theory’ and that the Mid-Cayman Rise should be a spreading center, which lead Bob Ballard to come to this site and study it as a mid-ocean ridge.”

Multibeam bathymetry

With the perspective that this site may be a spreading center, Ballard and his team made more detailed maps using a technique called multibeam bathymetry. Multibeam bathymetry measures depth by sending sound waves down and recording the time it takes for them to bounce off the seafloor and return to the surface, similar to how a bat uses echolocation. 

When Trieste descended on the site, the scientists inside took photographs, but their ability to explore was limited, as Trieste couldn’t move around like Alvin or Jason. Despite this minimal data, the scientific team knew there was volcanic basalt in the deep parts of this ridge, confirming suspicions that, indeed, the Cayman Rise was a spreading center.

Want to find out why this particular site is so important to study? Stay tuned!