From ‘Finding Nemo’ to minerals — what riches lie in the deep sea?

Left: The first species ever recovered from the deep sea. Center: Rockfish use deep-sea carbonate formations at Hydrate Ridge, US, as a refuge. Right: Deep-sea corals such as the one pictured are a source of jewelery and other riches. -  SERPENT Project/D.O.B. Jones, L. Levin, UK's BIS Department
Left: The first species ever recovered from the deep sea. Center: Rockfish use deep-sea carbonate formations at Hydrate Ridge, US, as a refuge. Right: Deep-sea corals such as the one pictured are a source of jewelery and other riches. – SERPENT Project/D.O.B. Jones, L. Levin, UK’s BIS Department

As fishing and the harvesting of metals, gas and oil have expanded deeper and deeper into the ocean, scientists are drawing attention to the services provided by the deep sea, the world’s largest environment. “This is the time to discuss deep-sea stewardship before exploitation is too much farther underway,” says lead-author Andrew Thurber. In a review published today in Biogeosciences, a journal of the European Geosciences Union (EGU), Thurber and colleagues summarise what this habitat provides to humans, and emphasise the need to protect it.

“The deep sea realm is so distant, but affects us in so many ways. That’s where the passion lies: to tell everyone what’s down there and that we still have a lot to explore,” says co-author Jeroen Ingels of Plymouth Marine Laboratory in the UK.

“What we know highlights that it provides much directly to society,” says Thurber, a researcher at the College of Earth, Ocean and Atmospheric Sciences at Oregon State University in the US. Yet, the deep sea is facing impacts from climate change and, as resources are depleted elsewhere, is being increasingly exploited by humans for food, energy and metals like gold and silver.

“We felt we had to do something,” says Ingels. “We all felt passionate about placing the deep sea in a relevant context and found that there was little out there aimed at explaining what the deep sea does for us to a broad audience that includes scientists, the non-specialists and ultimately the policy makers. There was a gap to be filled. So we said: ‘Let’s just make this happen’.”

In the review of over 200 scientific papers, the international team of researchers points out how vital the deep sea is to support our current way of life. It nurtures fish stocks, serves as a dumping ground for our waste, and is a massive reserve of oil, gas, precious metals and the rare minerals we use in modern electronics, such as cell phones and hybrid-car batteries. Further, hydrothermal vents and other deep-sea environments host life forms, from bacteria to sponges, that are a source of new antibiotics and anti-cancer chemicals. It also has a cultural value, with its strange species and untouched habitats inspiring books and films from 20,000 Leagues Under the Sea to Finding Nemo.

“From jewellery to oil and gas and future potential energy reserves as well as novel pharmaceuticals, deep-sea’s worth should be recognised so that, as we decide how to use it more in the future, we do not inhibit or lose the services that it already provides,” says Thurber.

The deep sea (ocean areas deeper than 200m) represents 98.5% of the volume of our planet that is hospitable to animals. It has received less attention than other environments because it is vast, dark and remote, and much of it is inaccessible to humans. But it has important global functions. In the Biogeosciences review the team shows that deep-sea marine life plays a crucial role in absorbing carbon dioxide from the atmosphere, as well as methane that occasionally leaks from under the seafloor. In doing so, the deep ocean has limited much of the effects of climate change.

This type of process occurs over a vast area and at a slow rate. Thurber gives other examples: manganese nodules, deep-sea sources of nickel, copper, cobalt and rare earth minerals, take centuries or longer to form and are not renewable. Likewise, slow-growing and long-lived species of fish and coral in the deep sea are more susceptible to overfishing. “This means that a different approach needs to be taken as we start harvesting the resources within it.”

By highlighting the importance of the deep sea and identifying the traits that differentiate this environment from others, the researchers hope to provide the tools for effective and sustainable management of this habitat.

“This study is one of the steps in making sure that the benefits of the deep sea are understood by those who are trying to, or beginning to, regulate its resources,” concludes Thurber. “We ultimately hope that it will be a useful tool for policy makers.”

Team develops a geothermometer for methane formation

John Eiler (left) and Daniel Stolper (right) with the Caltech-led team's prototype mass spectrometer -- the Thermo IRMS 253 Ultra. This instrument is the first equipped to measure abundances of rare isotopic versions of complex molecules, even where combinations of isotopic substitutions result in closely similar masses. This machine enabled the first precise measurements of molecules of methane that contain two heavy isotopes -- 13CH3D, which incorporates both a carbon-13 atom and a deuterium atom, and 12CH2D2, which includes two deuterium atoms. -  Caltech
John Eiler (left) and Daniel Stolper (right) with the Caltech-led team’s prototype mass spectrometer — the Thermo IRMS 253 Ultra. This instrument is the first equipped to measure abundances of rare isotopic versions of complex molecules, even where combinations of isotopic substitutions result in closely similar masses. This machine enabled the first precise measurements of molecules of methane that contain two heavy isotopes — 13CH3D, which incorporates both a carbon-13 atom and a deuterium atom, and 12CH2D2, which includes two deuterium atoms. – Caltech

Methane is a simple molecule consisting of just one carbon atom bound to four hydrogen atoms. But that simplicity belies the complex role the molecule plays on Earth-it is an important greenhouse gas, is chemically active in the atmosphere, is used in many ecosystems as a kind of metabolic currency, and is the main component of natural gas, which is an energy source.

Methane also poses a complex scientific challenge: it forms through a number of different biological and nonbiological processes under a wide range of conditions. For example, microbes that live in cows’ stomachs make it; it forms by thermal breakdown of buried organic matter; and it is released by hot hydrothermal vents on the sea floor. And, unlike many other, more structurally complex molecules, simply knowing its chemical formula does not necessarily reveal how it formed. Therefore, it can be difficult to know where a sample of methane actually came from.

But now a team of scientists led by Caltech geochemist John M. Eiler has developed a new technique that can, for the first time, determine the temperature at which a natural methane sample formed. Since methane produced biologically in nature forms below about 80°C, and methane created through the thermal breakdown of more complex organic matter forms at higher temperatures (reaching 160°C�°C, depending on the depth of formation), this determination can aid in figuring out how and where the gas formed.

A paper describing the new technique and its first applications as a geothermometer appears in a special section about natural gas in the current issue of the journal Science. Former Caltech graduate student Daniel A. Stolper (PhD ’14) is the lead author on the paper.

“Everyone who looks at methane sees problems, sees questions, and all of these will be answered through basic understanding of its formation, its storage, its chemical pathways,” says Eiler, the Robert P. Sharp Professor of Geology and professor of geochemistry at Caltech.

“The issue with many natural gas deposits is that where you find them-where you go into the ground and drill for the methane-is not where the gas was created. Many of the gases we’re dealing with have moved,” says Stolper. “In making these measurements of temperature, we are able to really, for the first time, say in an independent way, ‘We know the temperature, and thus the environment where this methane was formed.'”

Eiler’s group determines the sources and formation conditions of materials by looking at the distribution of heavy isotopes-species of atoms that have extra neutrons in their nuclei and therefore have different chemistry. For example, the most abundant form of carbon is carbon-12, which has six protons and six neutrons in its nucleus. However, about 1 percent of all carbon possesses an extra neutron, which makes carbon-13. Chemicals compete for these heavy isotopes because they slow molecular motions, making molecules more stable. But these isotopes are also very rare, so there is a chemical tug-of-war between molecules, which ends up concentrating the isotopes in the molecules that benefit most from their stabilizing effects. Similarly, the heavy isotopes like to bind, or “clump,” with each other, meaning that there will be an excess of molecules containing two or more of the isotopes compared to molecules containing just one. This clumping effect is strong at low temperatures and diminishes at higher temperatures. Therefore, determining how many of the molecules in a sample contain heavy isotopes clumped together can tell you something about the temperature at which the sample formed.

Eiler’s group has previously used such a “clumped isotope” technique to determine the body temperatures of dinosaurs, ground temperatures in ancient East Africa, and surface temperatures of early Mars. Those analyses looked at the clumping of carbon-13 and oxygen-18 in various minerals. In the new work, Eiler and his colleagues were able to examine the clumping of carbon-13 and deuterium (hydrogen-2).

The key enabling technology was a new mass spectrometer that the team designed in collaboration with Thermo Fisher, mixing and matching existing technologies to piece together a new platform. The prototype spectrometer, the Thermo IRMS 253 Ultra, is equipped to analyze samples in a way that measures the abundances of several rare versions, or isotopologues, of the methane molecule, including two “clumped isotope” species: 13CH3D, which has both a carbon-13 atom and a deuterium atom, and 12CH2D2, which includes two deuterium atoms.

Using the new spectrometer, the researchers first tested gases they made in the laboratory to make sure the method returned the correct formation temperatures.

They then moved on to analyze samples taken from environments where much is known about the conditions under which methane likely formed. For example, sometimes when methane forms in shale, an impermeable rock, it is trapped and stored, so that it cannot migrate from its point of origin. In such cases, detailed knowledge of the temperature history of the rock constrains the possible formation temperature of methane in that rock. Eiler and Stolper analyzed samples of methane from the Haynesville Shale, located in parts of Arkansas, Texas, and Louisiana, where the shale is not thought to have moved much after methane generation. And indeed, the clumped isotope technique returned a range of temperatures (169°C�°C) that correspond well with current reservoir temperatures (163°C�°C). The method was also spot-on for methane collected from gas that formed as a product of oil-eating bugs living on top of oil reserves in the Gulf of Mexico. It returned temperatures of 34°C and 48°C plus or minus 8°C for those samples, and the known temperatures of the sampling locations were 42°C and 48°C, respectively.

To validate further the new technique, the researchers next looked at methane from the Marcellus Shale, a formation beneath much of the Appalachian basin, where the gas-trapping rock is known to have formed at high temperature before being uplifted into a cooler environment. The scientists wanted to be sure that the methane did not reset to the colder temperature after formation. Using their clumped isotope technique, the researchers verified this, returning a high formation temperature.

“It must be that once the methane exists and is stable, it’s a fossil remnant of what its formation environment was like,” Eiler says. “It only remembers where it formed.”

An important application of the technique is suggested by the group’s measurements of methane from the Antrim Shale in Michigan, where groundwater contains both biologically and thermally produced methane. Clumped isotope temperatures returned for samples from the area clearly revealed the different origins of the gases, hitting about 40°C for a biologically produced sample and about 115°C for a sample involving a mix of biologically and thermally produced methane.

“There are many cases where it is unclear whether methane in a sample of groundwater is the product of subsurface biological communities or has leaked from petroleum-forming systems,” says Eiler. “Our results from the Antrim Shale indicate that this clumped isotope technique will be useful for distinguishing between these possible sources.”

One final example, from the Potiguar Basin in Brazil, demonstrates another way the new method will serve geologists. In this case the methane was dissolved in oil and had been free to migrate from its original location. The researchers initially thought there was a problem with their analysis because the temperature they returned was much higher than the known temperature of the oil. However, recent evidence from drill core rocks from the region shows that the deepest parts of the system actually got very hot millions of years ago. This has led to a new interpretation suggesting that the methane gas originated deep in the system at high temperatures and then percolated up and mixed into the oil.

“This shows that our new technique is not just a geothermometer for methane formation,” says Stolper. “It’s also something you can use to think about the geology of the system.”

Hard rock life

Scientists are digging deep into the Earth’s surface collecting census data on the microbial denizens of the hardened rocks. What they’re finding is that, even miles deep and halfway across the globe, many of these communities are somehow quite similar.

The results, which were presented at the American Geophysical Union conference Dec. 8, suggest that these communities may be connected, said Matthew Schrenk, Michigan State University geomicrobiologist.

“Two years ago we had a scant idea about what microbes are present in subsurface rocks or what they eat,” he said. “We’re now getting this emerging picture not only of what sort of organisms are found in these systems but some consistency between sites globally – we’re seeing the same types of organisms everywhere we look.”

Schrenk leads a team funded by the Alfred P. Sloan Foundation’s Deep Carbon Observatory studying samples from deep underground in California, Finland and from mine shafts in South Africa. The scientists also collect microbes from the deepest hydrothermal vents in the Caribbean Ocean.

“It’s easy to understand how birds or fish might be similar oceans apart,” Schrenk said. “But it challenges the imagination to think of nearly identical microbes 16,000 kilometers apart from each other in the cracks of hard rock at extreme depths, pressures and temperatures.”

Cataloging and exploring this region, a relatively unknown biome, could lead to breakthroughs in offsetting climate change, the discovery of new enzymes and processes that may be useful for biofuel and biotechnology research, he added.

For example, Schrenk’s future efforts will focus on unlocking answers to what carbon sources the microbes use, how they cope in such extreme conditions as well as how their enzymes evolved to function so deep underground.

“Integrating this region into existing models of global biogeochemistry and gaining better understanding into how deep rock-hosted organisms contribute or mitigate greenhouse gases could help us unlock puzzles surrounding modern-day Earth, ancient Earth and even other planets,” Schrenk said.

Collecting and comparing microbiological and geochemical data across continents is made possible through the DCO. The DCO has allowed scientists from across disciplines to better understand and describe these phenomena, he added.

Extreme water

Earth is the only known planet that holds water in massive quantities and in all three phase states. But the earthly, omnipresent compound water has very unusual properties that become particularly evident when subjected to high pressure and high temperatures. In the latest issue of the Proceedings of the National Academy of Sciences (PNAS), a German-Finnish-French team published what happens when water is subjected to pressure and temperature conditions such as those found in the deep Earth.

At pressures above 22 MPa and temperatures above 374°C, beyond the critical point, water turns into a very aggressive solvent, a fact that is crucial for the physical chemistry of Earth’s mantle and crust.

“Without water in Earth’s interior there would be no material cycles and no tectonics. But how the water affects processes in the upper mantle and crust is still subject of intense research”, said Dr. Max Wilke from the GFZ German Research Centre for Geosciences, who carried out the experiments along with his colleague Dr. Christian Schmidt and a team from the TU Dortmund. To this end, the research team brought the water to the laboratory. First, the microscopic structure of water as a function of pressure and temperature was studied by means of X-ray Raman scattering. For that purpose, the diamond anvil cells of the GFZ were used at the European Synchrotron Radiation Facility ESRF in Grenoble. Inside the cell, a very small sample of water was enclosed, heated and brought to high temperatures and pressures. The data analysis was based on molecular dynamics simulations by the GFZ scientists Sandro Jahn.

“The study shows that the structure of water continuously develops from an ordered, polymerized structure to a disordered, marginally polymerized structure at supercritical conditions,” explains Max Wilke. “The knowledge of these structural properties of water in the deep earth is an important basis for the understanding of chemical distribution processes during metamorphic and magmatic processes.” This study provides an improved estimate of the behavior of water under extreme conditions during geochemical and geological processes. It is believed that the unique properties of supercritical water also control the behavior of magma.

More deep-sea vents discovered

Previously unknown deep-sea volcanic vents have been discovered in the Southern Ocean. -  NOC/SOES
Previously unknown deep-sea volcanic vents have been discovered in the Southern Ocean. – NOC/SOES

Scientists aboard the Royal Research Ship James Cook have discovered a new set of deep-sea volcanic vents in the chilly waters of the Southern Ocean. The discovery is the fourth made by the research team in three years, which suggests that deep-sea vents may be more common in our oceans than previously thought.

Using an underwater camera system, the researchers saw slender mineral spires three meters tall, with shimmering hot water gushing from their peaks, and gossamer-like white mats of bacteria coating their sides. The vents are at a depth of 520 metres in a newly-discovered seafloor crater close to the South Sandwich Islands, a remote group of islands around 500 kilometres south-east of South Georgia.

“When we caught the first glimpse of the vents, the excitement was almost overwhelming,” says Leigh Marsh, a University of Southampton PhD student who was on scientific watch at the time of the discovery.

Deep-sea vents are hot springs on the seafloor, where mineral-rich water nourishes lush colonies of microbes and deep-sea animals. In the three decades since scientists first encountered vents in the Pacific, around 250 have been discovered worldwide. Most have been found on a chain of undersea volcanoes called the mid-ocean ridge, however, and very few are known in the Antarctic.

“We’re finding deep-sea vents more rapidly than ever before,” says expedition leader Professor Paul Tyler of the University of Southampton’s School of Ocean and Earth Science, which is based at the National Oceanography Centre, Southampton. “And we’re finding some in places other than at mid-ocean ridges, where most have been seen before.”

By studying the new vents, the team hope to understand more about the distribution and evolution of life in the deep ocean, the role that deep-sea vents play in controlling the chemistry of the oceans, and the diversity of microbes that thrive in different conditions beneath the waves.

The researchers were exploring ‘Adventure Caldera’, a crater-like hole in the seafloor three kilometres across and 750 metres deep at its deepest point. Despite its size, Adventure Caldera was only discovered last year by geophysicists from the British Antarctic Survey.

The new vents are the fourth set to be discovered around Antarctica in three expeditions since 2009. Their discovery is part of a project funded by the UK Natural Environment Research Council (NERC), which involves researchers from the National Oceanography Centre in Southampton, the British Antarctic Survey in Cambridge, the Universities of Southampton, Newcastle, Oxford, Bristol and Leeds, and Woods Hole Oceanographic Institution in the US.

The current expedition is scheduled to end in Punta Arenas, Chile, on 22 February 22, and the team are posting regular updates and answering questions from school pupils via their expedition website at http://www.thesearethevoyages.net/

Expedition to Mid-Cayman Rise identifies unusual variety of deep sea vents

As storm clouds gather and seas deteriorate, a team recovers the hybrid vehicle Nereus aboard the R/V Cape Hatteras during an expedition to the Mid-Cayman Rise in October 2009. A search for new vent sites along the 110 km ridge, the expedition featured the first use of Nereus in 'autonomous' or free-swimming mode. - Photo Credit: Woods Hole Oceanographic Institution
As storm clouds gather and seas deteriorate, a team recovers the hybrid vehicle Nereus aboard the R/V Cape Hatteras during an expedition to the Mid-Cayman Rise in October 2009. A search for new vent sites along the 110 km ridge, the expedition featured the first use of Nereus in ‘autonomous’ or free-swimming mode. – Photo Credit: Woods Hole Oceanographic Institution

The first expedition to search for deep-sea hydrothermal vents along the Mid-Cayman Rise has turned up three distinct types of hydrothermal venting, reports an interdisciplinary team led by Woods Hole Oceanographic Institution (WHOI) in this week’s Proceedings of the National Academy of Sciences. The work was conducted as part of a NASA-funded effort to search extreme environments for geologic, biologic, and chemical clues to the origins and evolution of life.

Hydrothermal activity occurs on spreading centers all around the world. However, the diversity of the newly discovered vent types, their geologic settings and their relative geographic isolation make the Mid-Cayman Rise a unique environment in the world’s ocean.

“This was probably the highest risk expedition I have ever undertaken,” said chief scientist Chris German, a WHOI geochemist who has pioneered the use of autonomous underwater vehicles (AUVs) to search for hydrothermal vent sites. “We know hydrothermal vents appear along ridges approximately every 100 km. But this ridge crest is only 100 km long, so we should only have expected to find evidence for one site at most. So finding evidence for three sites was quite unexpected – but then finding out that our data indicated that each site represents a different style of venting – one of every kind known, all in pretty much the same place – was extraordinarily cool.”

The Mid-Cayman Rise (MCR) is an ultraslow spreading ridge located in the Cayman Trough – the deepest point in the Caribbean Sea and a part of the tectonic boundary between the North American Plate and the Caribbean Plate. At the boundary where the plates are being pulled apart, new material wells up from Earth’s interior to form new crust on the seafloor.

The team identified the deepest known hydrothermal vent site and two additional distinct types of vents, one of which is believed to be a shallow, low temperature vent of a kind that has been reported only once previously – at the “Lost City” site in the mid-Atlantic ocean.

“Being the deepest, these hydrothermal vents support communities of organisms that are the furthest from the ocean surface and sources of energy like sunlight,” said co-author Max Coleman of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “Most life on Earth is sustained by food chains that begin with sunlight as their energy source. That’s not an option for possible life deep in the ocean of Jupiter’s icy moon Europa, prioritized by NASA for future exploration. However, organisms around the deep vents get energy from the chemicals in hydrothermal fluid, a scenario we think is similar to the seafloor of Europa, and this work will help us understand what we might find when we search for life there.”

Approach

While vent sites occupy small areas on the sea floor, the plumes formed when hot acidic vent fluids mix with cold deep-ocean seawater can rise hundreds of meters until they reach neutral buoyancy. Because these plumes contain dissolved chemicals, particulate minerals and microbes, they can then be detected for kilometers or more away from their source as they disperse horizontally in the ocean. The chemical signatures of these plumes vary according to the type of vent site from which they originated.

The three known types of vent sites are distinguished by the kinds of rock that host the sites. The first type of vents occur throughout the world’s mid-ocean ridges and are hosted by rocks that are rich in magnesium and iron –called mafic rocks. The second and third types of vent sites are hosted in rocks called ultramafic that form deep below the seafloor and are composed of material similar to the much hotter lavas that erupted on Earth’s very earliest seafloor, thousands of millions of years ago.

The discovery of ultramafic-hosted vent sites such as those on the Mid-Cayman Rise could provide insight into the very earliest life on our planet and the potential for similar life to become established elsewhere,” said German.

For this mission, German and his colleagues used the plumes in the search for hydrothermal vents, employing sensors mounted on equipment and robotic vehicles to track the chemicals back to their source. This expedition used a CTD (conductivity, temperature, and depth) array augmented with sensors to detect suspended particles and anomalous chemical compositions (the latter sensor courtesy of Ko-ichi Nakamura from AIST in Tsukuba, Japan) mounted on both a water sampling rosette and the hybrid vehicle Nereus, a deep-diving robot that can operate in both in tethered and free-swimming modes.

Using the CTDs and Nereus in “autonomous” or free-swimming mode, the team sniffed out deep-sea plumes originating from the seafloor hydrothermal vents. Using a combination of shipboard and shore-based analysis of water samples for both their chemical and microbial contents, the team was then able to track the plumes toward their sources as well as to determine the likely nature of the venting present at each site. The ultimate goal was to switch Nereus into tethered or “remotely operated” (ROV) mode during the latter stages of the cruise and dive on each vent site to collect samples using Nereus’ robotic manipulator arm.

“Part of the excitement of this NASA-funded project was the success of deploying a full-ocean-capable tethered vehicle to search for vents at 5000 m from the R/V Cape Hatteras, which, at 41 meters in length, is one of the smallest ocean-going ships in the national fleet. This is a first,” said Cindy Lee Van Dover, co-author on the study and director of the Duke University Marine Laboratory.

The first two sites the team identified are extremely deep and were named Piccard and Walsh in honor of the only two humans to dive to the Challenger Deep – the deepest part of the world’s ocean. The plume detected at the Piccard site – 800 meters deeper than the previously known deepest vent – was comparable to plumes from the “Type 1″ vent sites, first found in the Pacific Ocean in 1977.

“We were particularly excited to find compelling evidence for high-temperature venting at almost 5000m depth. We have absolutely zero microbial data from high-temperature vents at this depth,” said Julie Huber, a scientist in the Josephine Bay Paul Center at the Marine Biological Laboratory (MBL) in Woods Hole. Huber and MBL postdoctoral scientist Julie Smith participated in this cruise to collect samples, and all of the microbiology work for this paper was carried out in Huber’s laboratory. “With the combination of extreme pressure, temperature, and chemistry, we are sure to discover novel microbes in this environment,” Huber added. “We look forward to returning to the Cayman and sampling these vents in the near future. We are sure to expand the known growth parameters and limits for life on our planet by exploring these new sites.”

The Walsh plume also exhibited signals characteristic of a high temperature site, but with a chemical composition (notably the high methane-to-manganese ratio) typically found at a high temperature, ultramafic hosted “Type 2″ vent site. The third site – which the team have named Europa, after the moon of Jupiter – most closely resembles the “Lost City” vent site in the mid-Atlantic ocean- to date the only confirmed low-temperature “Type 3″ site.

Half way through the six-day leg in which Nereus was converted into ROV mode, tropical storm Ida intervened and stopped the team from viewing or sampling the vent site. Though they had come within <250m of the vents at the seafloor, they had to ride out the storm for the last three days of the cruise and return to port frustrated. Happily, however, all was not lost – the research team shared their findings with an international team led by Jon Copley of the National Oceanography Centre in Southampton, UK, who returned to the MCR in Spring 2010 and imaged active vents at both the Piccard and Europa locations using a deep-towed camera called Hybis.

“Given the range and diversity of systems present, and now that we have established exactly where the sites are and what they look like, we really can’t wait to get back and collect first samples with our ROV Jason,” said German. “This region has the potential to develop into an exciting natural laboratory with plenty of potential for repeat visits and long-term experiments over the decade ahead.”

By exploring this extreme and previously uninvestigated section of the Earth’s deep seafloor, the researchers seek to extend our understanding of the limits to which life can exist on Earth and to help prepare for future efforts to explore for life on other planets.

British scientific expedition discovers world’s deepest known undersea volcanic vents

First photograph of the world's deepest known 'black smoker' vent, erupting water hot enough to melt lead, 3.1 miles deep on the ocean floor -  NOC
First photograph of the world’s deepest known ‘black smoker’ vent, erupting water hot enough to melt lead, 3.1 miles deep on the ocean floor – NOC

A British scientific expedition has discovered the world’s deepest undersea volcanic vents, known as ‘black smokers’, 3.1 miles (5000 meters) deep in the Cayman Trough in the Caribbean. Using a deep-diving vehicle remotely controlled from the Royal Research Ship James Cook, the scientists found slender spires made of copper and iron ores on the seafloor, erupting water hot enough to melt lead, nearly half a mile deeper than anyone has seen before.

Deep-sea vents are undersea springs where superheated water erupts from the ocean floor. They were first seen in the Pacific three decades ago, but most are found between one and two miles deep. Scientists are fascinated by deep-sea vents because the scalding water that gushes from them nourishes lush colonies of deep-sea creatures, which has forced scientists to rewrite the rules of biology. Studying the life-forms that thrive in such unlikely havens is providing insights into patterns of marine life around the world, the possibility of life on other planets, and even how life on Earth began.

The expedition to the Cayman Trough is being run by Drs Doug Connelly, Jon Copley, Bramley Murton, Kate Stansfield and Professor Paul Tyler, all from Southampton, UK. They used a robot submarine called Autosub6000, developed by engineers at the National Oceanography Centre (NOC) in Southampton, to survey the seafloor of the Cayman Trough in unprecedented detail. The team then launched another deep-sea vehicle called HyBIS, developed by team member Murton and Berkshire-based engineering company Hydro-Lek Ltd, to film the world’s deepest vents for the first time.

“Seeing the world’s deepest black-smoker vents looming out of the darkness was awe-inspiring,” says Copley, a marine biologist at the University of Southampton’s School of Ocean and Earth Science (SOES) based at the NOC and leader of the overall research programme. “Superheated water was gushing out of their two-storey high mineral spires, more than three miles deep beneath the waves”. He added: “We are proud to show what British underwater technology can achieve in exploring this frontier – the UK subsea technology sector is worth £4 billion per year and employs 40 000 people, which puts it on a par with our space industry.”

The Cayman Trough is the world’s deepest undersea volcanic rift, running across the seafloor of the Caribbean. The pressure three miles deep at the bottom of the Trough – 500 times normal atmospheric pressure – is equivalent to the weight of a large family car pushing down on every square inch of the creatures that live there, and on the undersea vehicles that the scientists used to reveal this extreme environment. The researchers will now compare the marine life in the abyss of the Cayman Trough with that known from other deep-sea vents, to understand the web of life throughout the deep ocean. The team will also study the chemistry of the hot water gushing from the vents, and the geology of the undersea volcanoes where these vents are found, to understand the fundamental geological and geochemical processes that shape our world.

“We hope our discovery will yield new insights into biogeochemically important elements in one of the most extreme naturally occurring environments on our planet,” says geochemist Doug Connelly of the NOC, who is the Principal Scientist of the expedition.

“It was like wandering across the surface of another world,” says geologist Bramley Murton of the NOC, who piloted the HyBIS underwater vehicle around the world’s deepest volcanic vents for the first time. “The rainbow hues of the mineral spires and the fluorescent blues of the microbial mats covering them were like nothing I had ever seen before.”

“Our multidisciplinary approach – which brings together physics, chemistry, geology and biology with state-of-the-art underwater technology – has allowed us to find deep-sea vents more quickly than ever before,” adds oceanographer Kate Stansfield of the NOC.

The team aboard the ship includes students from the UK, Ireland, Germany and Trinidad. “This expedition has been a superb opportunity to train the next generation of marine scientists at the cutting edge of deep-sea research,” says marine biologist Paul Tyler of SOES, who heads the international Census of Marine Life Chemosynthetic Ecosystems (ChEss) programme.

The expedition will continue to explore the depths of the Cayman Trough until 20th April. The team are posting daily updates on their expedition website at http://www.thesearethevoyages.net/, including photos and videos from their research ship. “We look forward to sharing the excitement of exploring the deep ocean with people around the world,” says Copley.

In addition to the scientists from Southampton, the team aboard the ship includes researchers from the University of Durham in the UK, the University of North Carolina Wilmington and the University of Texas in the US, and the University of Bergen in Norway. The expedition members are also working with colleagues ashore at Woods Hole Oceanographic Institution and Duke University in the US to analyze the deep-sea vents.

The expedition is part of a research project funded by the UK Natural Environment Research Council to study the world’s deepest undersea volcanoes. The research team will return to the Cayman Trough for a second expedition using the UK’s deep-diving remotely-operated vehicle Isis, once a research ship is scheduled for the next phase of their project.

Scientists locate apparent hydrothermal vents off Antarctica

A vent spews chemical fluids from the East Pacific Rise, about 5,600 miles from newly suspected vents on the Pacific Antarctic Ridge. -  Woods Hole Oceanographic Institution
A vent spews chemical fluids from the East Pacific Rise, about 5,600 miles from newly suspected vents on the Pacific Antarctic Ridge. – Woods Hole Oceanographic Institution

Scientists at Columbia University’s Lamont-Doherty Earth Observatory have found evidence of hydrothermal vents on the seafloor near Antarctica, formerly a blank spot on the map for researchers wanting to learn more about seafloor formation and the bizarre life forms drawn to these extreme environments.

Hydrothermal vents spew volcanically heated seawater from the planet’s underwater mountain ranges-the vast mid-ocean ridge system, where lava erupts and new crust forms. Chemicals dissolved in those vents influence ocean chemistry and sustain a complex web of organisms, much as sunlight does on land. In recent decades more than 220 vents have been discovered worldwide, but so far no one has looked for them in the rough and frigid waters off Antarctica.

From her lab in Palisades, N.Y., geochemist Gisela Winckler recently took up the search. By analyzing thousands of oceanographic measurements, she and her Lamont colleagues pinpointed six spots on the remote Pacific Antarctic Ridge, about 2,000 miles from New Zealand, the closest inhabited country, and 1,000 miles from the west coast of Antarctica, where they think vents are likely to be found. The sites are described in a paper published THIS WEEK in the journal Geophysical Research Letters.

“Most of the deep ocean is like a desert, but these vents are oases of life and weirdness,” said Winckler. “The Pacific Antarctic ridge is one of the ridges we know least about. It would be fantastic if researchers were to dive to the seafloor to study the vents we believe are there.”

Two important facts helped the scientists isolate the hidden vents. First, the ocean is stratified with layers of lighter water sitting on top of layers of denser water. Second, when a seafloor vent erupts, it spews gases rich in rare helium-3, an isotope found in earth’s mantle and in the magma bubbling below the vent. As helium-3 disperses through the ocean, it mixes into a density layer and stays there, forming a plume that can stretch over thousands of kilometers.

The Lamont scientists were analyzing ocean-helium measurements to study how the deep ocean exchanges dissolved gases with the atmosphere when they came across a helium plume that looked out of place. It was in a southern portion of the Pacific Ocean, below a large and well-known helium plume coming off the East Pacific Rise, one of the best-studied vent regions on earth. But this mystery plume appeared too deep to have the same source.

Suspecting that it was coming from the Pacific Antarctic Ridge instead, the researchers compiled a detailed map of ocean-density layers in that region, using some 25,000 salinity, temperature and depth measurements. After locating the helium plume along a single density layer, they compared the layer to topographic maps of the Pacific Antarctic Ridge to figure out where the plume would intersect.

The sites they identified cover 340 miles of ridge line–the approximate distance between Manhattan and Richmond, Va.–or about 7 percent of the total 4,300 mile-ridge. This chain of volcanic mountains lies about three miles below the ocean surface, and its mile-high peaks are cut by steep canyons and fracture zones created as the sea floor spreads apart. It is a cold and lonely stretch of ocean, far from land or commercial shipping lanes.

“They haven’t found vents, but they’ve narrowed the places to look by quite a bit,” said Edward Baker, a vent expert at the National Oceanic and Atmospheric Administration.

Of course, finding vents in polar waters is not easy, even with a rough idea where to look. In 2007, Woods Hole Oceanographic Institution geophysicist Rob Reves-Sohn led a team of scientists to the Gakkel Ridge between Greenland and Siberia to look for vents detected six years earlier. Although they discovered regions where warm fluids appeared to be seeping from the seafloor, they failed to find the high-temperature, black smoker vents they had come for. In a pending paper, Sohn now says he has narrowed down the search to a 400-kilometer-square area where he expects to find seven new vents, including at least one black smoker.

The search for vents off Antarctica may be equally unpredictable, but the map produced by the Lamont scientists should greatly improve the odds of success, said Robert Newton, a Lamont oceanographer and study co-author. “You don’t have to land right on top of a vent to know it’s there,” he said. “You get a rich mineral soup coming out of these smokers-methane, iron, manganese, sulphur and many other minerals. Once you get within a few tens of kilometers, you can detect these other tracers.”

Since the discovery of the first hydrothermal vents in the late 1970s, scientists have searched for far-flung sites, in the hunt for new species and adaptive patterns that can shed light on how species evolved in different spots. Cindy Van Dover, a deep sea biologist and director of the Duke University Marine Laboratory, says she expects that new species will be found on the Pacific Antarctic Ridge, and that this region may hold important clues about how creatures vary between the Indian and Pacific Oceans, on either end.

“These vents are living laboratories,” said Van Dover, who was not involved in the study. “When we went to the Indian Ocean, we discovered the scaly-foot gastropod, a deep-sea snail whose foot is covered in armor made of iron sulfides. The military may be interested in studying the snail to develop a better armor. The adaptations found in these animals may have many other applications.”

Ancient geologic escape hatches mistaken for tube worms

Tubeworms have been around for millions of years and the fossil record is rich with their distinctive imprints. But a discovery made by U of C scientists found that what previous researchers had labeled as tubeworms in a formation near Denver, Colorado, are actually 70 million-year-old escape hatches for methane.

Tubeworms, or siboglinids, look like long lipstick tubes and have been observed in warm and cold environments on the ocean floor, as well as in whale carcasses and decomposing organic-rich cargoes in sunken ships. Ecosystems teeming with tubeworm colonies were discovered at hydrothermal vents in the Galapagos Ridge in 1977 and at cold seeps at the base of the Florida Escarpment in 1984. As a result of these modern sightings, a number of fossil examples of tubeworms were subsequently identified in the rock record. One of these localities, found south of Denver, Colorado, was recently re-examined by U of C scientists.

In an area approximately one and a half times the size of the City of Calgary, scientists discovered that what was previously identified as fossilized tubeworms were actually fossilized tubular escape hatches for methane, a major constituent of natural gas.

“It is the first time that evidence of a natural ancient geologic conduit system has been discovered where gas, water and solids were all being vented at once,” says Federico Krause, the lead author of the paper which is co-authored by Selim Sayegh, an adjunct professor in geoscience, Jesse Clark, a former undergraduate student, and Renee Perez, research associate in the Department of Chemical and Petroleum Engineering. The paper is published in this month’s edition of Palaios.

The discovery was made possible thanks to the Stable Isotope Laboratory of the Department of Physics and Astronomy and the electronic microprobe housed in the Department of Geoscience. Stable isotopes and chemical elements maps demonstrated that not only methane gas bubbles were being expelled but that solid particles that had adhered to the bubbles were also being ejected from the fossil vents.

Although the results may be surprising, the ramifications are even more so.

The fact that methane gas can escape from a thick shale seafloor may demonstrate that there needs to be more research done on the integrity of geologic seals in petroleum reservoirs earmarked for CO2 injection,” says Krause who is a professor in the Department of Geoscience at the University of Calgary. “It shows that under different geologic circumstances gases that are present in underground formations can indeed seep out, and all the effort expended in trying to remove CO2 from our atmosphere would be lost.”

In addition, there are vast volumes of methane gas naturally trapped beneath the seafloor in the form of gas hydrates. If these hydrates were to be destabilized, methane bubbles could release large quantities of microparticles to the ocean bottom. This release would cloud up the deep ocean and the effect would be akin to fouling up the atmosphere with a dense smog. Given that the ocean bottom is one of the last frontiers of petroleum exploration, further research will be needed to properly plan for the location of production and containment facilities on the seafloor. Installation of these facilities has the potential to destabilize underlying hydrates.

“These 70-million-year-old tubular escape hatches south of Denver, Colorado, provide a glimpse to processes that are occurring in the ocean bottoms at present,” says Krause. “While finding tubeworms would have been satisfying, uncovering tubular gas vents has been much more exciting.”

Scientists break record by finding northernmost hydrothermal vent field





The top three feet of a chimney nearly 40 feet tall are visible as the arm of a remotely operated vehicle reaches in to sample fluids. The vent is part of the northernmost hydrothermal vent field yet seen and sampled. - Credit: Centre for Geobiology/U. of Bergen
The top three feet of a chimney nearly 40 feet tall are visible as the arm of a remotely operated vehicle reaches in to sample fluids. The vent is part of the northernmost hydrothermal vent field yet seen and sampled. – Credit: Centre for Geobiology/U. of Bergen

Well inside the Arctic Circle, scientists have found black smoker vents farther north than anyone has ever seen before. The cluster of five vents — one towering nearly four stories in height — are venting water as hot as 570 F.



Dissolved sulfide minerals that solidify when vent water hits the icy cold of the deep sea have, over the years, accumulated around the vent field in what is one of the most massive hydrothermal sulfide deposits ever found on the seafloor, according to Marvin Lilley, a University of Washington oceanographer. He’s a member of an expedition led by Rolf Pedersen, a geologist with the University of Bergen’s Centre for Geobiology, aboard the research vessel G.O. Sars.



The vents are located at 73 degrees north on the Mid-Atlantic Ridge between Greenland and Norway. That’s more than 120 miles from the previous northernmost vents found during a 2005 expedition, also led by Pedersen. Other scientists have detected plumes of water from hydrothermal vents even farther north but have been unable to find the vent fields on the seafloor to image and sample them.



In recent years scientists have been interested in knowing how far north vigorous venting extends. That’s because the ridges where such fields form are so stable up north, usually subject only to what scientists term “ultra-slow” spreading. That’s where tectonic forces are pulling the seafloor apart at a rate as little as 6/10th of an inch in a year. This compares to lower latitudes where spreading can be up to eight times that amount, and fields of hydrothermal vents are much more common.



“We hadn’t expected a lot of active venting on ultra-slow spreading ridges,” Lilley said.


The active chimneys in the new field are mostly black and covered with white mats of bacteria feasting on the minerals emitted by the vents. Older chimneys are mottled red as a result of iron oxidization. All are the result of seawater seeping into the seafloor, coming near fiery magma and picking up heat and minerals until the water vents back into the ocean. The same process created the huge mound of sulfide minerals on which the vents sit. That deposit is about 825 feet in diameter at its base and about 300 feet across on the top and might turn out to be the largest such deposit seen on the seafloor, Lilley said. Additional mapping is needed.



“Given the massive sulfide deposit, the vent field must surely have been active for many thousands of years,” he said.



The field has been named Loki’s Castle partly because the small chimneys at the site looked like a fantasy castle to the scientists. The Loki part refers to a Norwegian god renowned for trickery. A University of Bergen press release about the discovery said Loki “was an appropriate name for a field that was so difficult to locate.”



Indeed this summer’s expedition and the pinpointing of the location of the vents earlier this month follows nearly a decade of research. Finding the actual field involved extensive mapping. It also meant sampling to detect warm water and using optical sensors lowered in the ocean to determine the chemistry, both parts that involved Lilley. He said a key sensor was one developed by Ko-ichi Nakamura of the National Institute of Advanced Science and Technology, Japan, that detects reduced chemicals that are in the water as a result of having been processed through a hydrothermal vent.



A remotely operated vehicle was used to finally find the vents. The difficulties of the task are described in an expedition Web diary, see “Day 17: And then there were vents” at http://www.geobio.uib.no/View.aspx?mid=1062&itemid=90&pageid=1093&moduledefid=71.



The area around the vents was alive with microorganisms and animals. Preliminary observations suggest that the ecosystem around these Arctic vents is diverse and appears to be unique, unlike the vent communities observed elsewhere, the University of Bergen press release said. The expedition included 25 participants from five countries.