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SO253/en

Logo http://geschichten.ptj.de/so253-en

Three days before Christmas Eve, the new German research vessel left the port of Nouméa with 39 researchers, one journalist, and 31 crew members on board bound for the Kermadec Arc.

We invite you to accompany us on this journey via this website.

Zum deutschen Expeditionsblog geht es hier

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The expedition SO253 takes the RV SONNE into the middle of the collision zone of two large tectonic plates. Here, the Pacific plate subducts under the Australian continental plate. At this intersection of the plates, a chain of volcanoes formed many millions of years ago, forming the Kermadec volcanic arc between New Zealand and Tonga. Only four of the more than 30 larger volcanoes stick out of the water, forming the Kermadec islands: Raoul Island, Macauley Island, Curtis Island, and Nugent Island. The SONNE expedition, however, will dedicate its activities to the underwater volcanoes Macauley Cone, Haungaroa, Brothers, and Rumble III.

In the Kermadec arc, volcanic eruptions are frequent even in the present day. More information about the individual volcanoes can be found in the volcano database of Smithsonian Institute.

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The goal of the expedition is to investigate hydrothermal vents discharging at the submarine volcanoes. The scientists want to find out what influence the vents have on the seawater and on life in the vicinity of the hydrothermally active systems.  

„It is really spectacular to see how these 300 degrees hot fluid shoot out of the seafloor, and how life thrives under these extreme conditions."
Prof. Dr. Andrea Koschinsky

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The underwater robot ROV QUEST (MARUM) dives down to the hydrothermal vents and takes samples of the hot fluids at depths between 200 and 1,600 meters. It also samples biological material, rock, and ore samples, which are studied by the scientists on board RV SONNE during and after the cruise.

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The expedition SO253 is led by geochemist Prof. Dr. Andrea Koschinsky from Jacobs University Bremen.

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The participants from the cruise include biologists, physicists, chemists and geologists from the following research institutions:
Jacobs University, Bremen
MARUM, Universität Bremen
Institut für Biologie und Chemie des Meeres, Universität Oldenburg
Universität Hamburg
MPI für Marine Mikrobiologie, Bremen
Westfälische Wilhelms-Universität Münster
University of Otago, Neuseeland
GNS Science, Neuseeland
Centre Nationale pour la Recherche Scientifique
National Oceanic and Atmospheric Administration, USA

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SONNE Expedition SO253

Research topic: The influence of hydrothermal springs on the chemistry, geology and biology of the ocean
Leadership of the cruise: Prof. Dr. Andrea Koschinsky (Jacobs University Bremen)

Start: 22 December 2016, Nouméa (New Caledonia)
End: 21 January, 2017, Auckland (New Zealand)

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Here, the scientists of Expedition SO253 and journalist Marie Heidenreich let you take part in the cruise activities for six weeks, beginning December 22nd, 2016. This blog allows you to learn about the goals of our marine research and also see how we spend Christmas and New Year onboard the research vessel.

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All scientists have arrived on the beautiful island of New Caledonia, located between New Zealand and Papua New Guinea. We enjoy the tropical conditions here; the water pleasant at 26°C ... perfect for a swim. The coral reefs in the lagoon just off shore Noumea are home to a plethora of colorful fish. Today, we stepped aboard the research vessel SONNE for the first time.

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The harbor is located close to the city center and is easily accessible, unlike many other ports that are difficult to get in and out of. The locals of Noumea take interest in the SONNE as it is so distinct from the large cruise liners that commonly come to port here. While we board the vessel, our scientific gear is loaded onto the ship’s deck in 20-foot containers that were packed back in Germany two months ago. The remotely operated vehicle MARUM QUEST is part of the lot taken aboard while the ship is tied up to the pier in Noumea.

After we settled into our new home of the comfortable cabins on board, we quickly started to unpack the containers and move the gear into the various labs onboard the ship and secure everything for departure the next morning.

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At 9 a.m. today, the ship left the port of Noumea. We enjoyed the ride, while the ship was plowing through the beautiful scenery of picturesque patch islands in the turquoise water of the lagoon.

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We are headed for our first working area, the underwater volcano Macauley Cone, which lies in a marine protected area. Getting permission from the New Zealand officials to conduct research in these areas requires us to have the ship’s hull cleaned of organisms that may have colonized the surfaces during earlier cruises in different areas of the world’s oceans. Divers removed these unwanted colonizers in Noumea, and we are now waiting to obtain the permission to enter the protected area around Macauley Island.

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Two days before we got there, we obtained the permission to enter the marine protected area and conduct research at Macauley Cone. Phew, what a relief. We used the remaining time to present to each other the individual goals of the different research groups involved. The range of research topics is very large and includes seafloor mapping, sampling of rocks and hot fluids (water and gas) and investigating life in the hostile environments we are about to visit. It becomes obvious very quickly how challenging it is going to be for chief scientist Prof. Dr. Andrea Koschinsky to get all parties the samples they need to meet their specific research goals. Separate groups of scientists continue to discuss splitting and sharing of samples after the meeting has ended. Many scientists are particularly interested in sampling the hot fluids that escape from the seabed, much like geysers on land. Some of them need larger quantities than others, but the volume of sample is very limited for each vent site. In the end, everyone is happy with the sampling plan, which has not a droplet of fluid wasted.

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The Pacific is large and internet is slow here, which does not permit us to upload all of the images we’d like to display. Yesterday, all of us were shaken out of the cabins and labs to attend a safety drill. We all had to put on our life jackets and gather at the muster stations fully-equipped for an emergency. There is a stringent rescue plan in place that has each of us assigned to a rescue boat – one port (right hand) side and one starboard (left hand) side. The safety drill also brought out individuals on deck that had retreated to their cabin to fight seasickness. Although the weather is fine, there is a long ocean swell that has the ship rocking and rolling a bit. Thankfully, the ship’s doctor, Dr. Gabriele Wolters, has various kinds of medicine that help the ones suffering to overcome seasickness.  

If you shy away from taking medication, the seasoned sailor can recommend the following course of action: eat ginger root, spend time on deck and stare at the horizon, take naps, but continue eating regularly. Before going to bed, we moved the clocks one hour ahead to adjust for the new time zone, which has us 11 hours ahead of Central European Time.

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It is not easy to develop a Christmas feeling in bright sunshine and 25°C, but we try our best. The ship’s Master, Lutz Mallon, relayed this to the German founding agency in an interview today. In the meantime, the rest of us wrap small gifts each of had brought onboard and that are to be distributed in a lottery during the Christmas Evening party. All of us look forward to the festive dinner the cooks and stewards are preparing for us.

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Right after breakfast, we sent a water sampling device into the abyss. It is composed of 22 bottles, each can hold 10 liters of water, which can be closed electronically at depth. Central part of the device is a CTD, which stands for conductivity, temperature, and depth. That probe sends data up to the ship in real time during the deployment.

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„We have to lower the CTD to at least 2000 m water depth, because the temperatures, and hence sound velocities, change drastically within the water column“ says physical oceanographer Maren Walter from the University of Bremen. From the salinity, temperature and pressure data the CTD records, we can calculate the sound velocity profile of the ocean. This profile is required for producing maps of the seafloor we can process from acoustic measurements the ship’s echosounding system conducts. „Only if we know how fast sound travels through the water column can we precisely determine the depth of the seafloor underneath us“, Maren Walter continues. Instead of the 2040 m indicated by the echosounder at the CTD station, the seafloor turned out to be 2042 m deep. This discrepancy is minor, but it does make a difference for deploying our gear at the seabed.

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When the CTD-water bottle rosette surfaced after two hours it was immediately recovered on deck and sampled by the scientists. All different shapes and sizes of bottles and cans were used to retrieve water samples from different depths off the device. Maren Walter brough copper tubes to hold samples for noble gas measurements. The copper keeps Helium, which would escape from plactic bottles, dissolved in the water inside the tube.  

Corinna Oster uses a special kind of plastic bottles that do not release any kind of organic compounds to the water stored inside them. Seawater has organic molecules dissolved that Corinna Oster would like to examine. A US magazine described her research object as „the tea of the sea“. In her home institution, the institute for chemistry and biology of the sea of the University of Oldenburg, Corinna Oster uses mass spectrometers to determine the nature of the organic compounds dissolved in the water samples. „The samples I am taking today will be compared with samples from hydrothermally active area we will sample next week,“ explains Corinna Oster. This way, she can find out, how hydrothermal processes affect the composition of dissolved organic compounds in seawater.  

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Today, we get to see land again, as we stop 1.5 km off Macauley Island to investigate the subseafloor volcano of Macauley Cone. The island is rocky, barring a few shrubs, and has steep cliffs displaying layers of basaltic rock interspersed with a prominent layer of dacitic tephra that was deposited 6000 years ago during a large volcanic eruption. The ship is currently positioned above the center of that eruption.  

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The CTD was deployed late in the night. The goal this time was to get as close as possible to the hydrothermal vents to collect large volumes of water, which are required for some kinds of measurements. “We have successfully captured the extent of the hydrothermal plume,” chief scientist Andrea Koschinsky said after the station work was completed.  

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In the CTD laboratory, the scientists watch the data streams coming in with great anticipation and immediately respond by telling the bridge and winch operator how to adjust the course and water depth of the instrument. The goal is to find the core of the plume, where the concentration of vent water is highest. This activity is called “plume hunting”. The scientists monitor real time data of pressure and oxygen content, but the most important measurement for spotting the plumes is the recorded redox-potential, which indicates the presence of reduced chemicals, like metals and sulfide, that are emitted from hydrothermal vents. The higher the concentrations of iron (Fe2+) and hydrogen sulfide are, the closer the plume hunters are to the vents.

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As soon as the CTD with the water bottles is secured on deck, the scientists collect samples from the tall, gray sample bottles. Each of the 22 bottles holds a water sample from a different depth. The shallowest sample is from just 10 m water depth, while the deepest one is from 678 m, within the hydrothermal plume.

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After working on the water samples all night, Harald Strauß from the University of Münster announces: “I have conserved the samples for various measurements in our laboratories in Münster. Samples for carbon isotope analyses I poisoned, so that microbes cannot turn over carbon after sampling.” Other samples are stored in the cold and dark fridge. “Some samples gave off an intense rotten-egg-smell, which is indicative of elevated hydrogen sulfide concentrations. These samples, I treated so that the hydrogen sulfide does not get oxidized. I want to examine the different sulfur compounds, like hydrogen sulfide, sulfate, and elemental sulfur in rocks and animals. To accomplish this, all chemical reaction post-sampling have to be inhibited,” he explains.

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Now that the scientist know where the vents and plumes are, they want to find out how the plume particles are transported in the oceans. To accomplish this goal, they position a deep-sea pump in the middle of the particle cloud during the night hours, when the ROV is not being used. The pump sucks water through filters that collect the particles. Other scientists use so-called “gorilla wool” to collect trace amounts of radium dissolved in the water.  When the pump is back on board at 8 in the morning, the researchers can finally go to bed.

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After recovering the pump, ROV QUEST is launched at 9 a.m. to survey the flanks of the volcano crater, collecting rock samples and video of the seafloor. The scientists not involved in the CTD work take over and congregate in the meeting room, where all the video material is displayed on large screens. As soon as the scientists see interesting rock formations or animals, they can ask the ROV pilots to zoom in on the area and collect samples.

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The ROV also deploys heat flow blankets, circular pillows that measured how much heat escapes through the seafloor. “These blankets are do-it-yourself-constructions: the tube is from a motor cycle. Thermometers are attached above and underneath the blanket. From the temperature difference we can estimate the heat flow density”, explains Fabio Caratori Tontini, from the New Zealand research institution GNS Science. “For these measurements, it is essential that heat cannot bypass the blanket. This is why the blankets are equipped with a second tube filled with lead, which pushes the device firmly down on the seabed.”

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The flanks of submarine volcanos deliver large quantities of heat to the oceans. “With the heat flow blankets, we measure the amount of heat the volcano releases. I have the vision that my kids will see mankind use this enormous energy source. Many nations around the Pacific “ring of fire” are faced with an increasing energy demand. Underwater geothermal systems could provide clean and unlimited energy right to their doorsteps. We should perhaps start using oceanic resources to deal with these kinds of future challenges. This is happening for food and raw materials already, why not energy?” suggests New Zealand geologist Cornel de Ronde.

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The QUEST dive lasts all day long. We follow the ROV’s track through the volcano crater underneath our vessel in real time. In a water depth of 320 m, the seafloor is littered with mussels, sediments, and fragments of rock. Fish dart in the headlights of QUEST. Countless small flatfish are barely visible; they don’t seem to move around much, not even when a crab walks across them. When we arrive at the vent site, we notice copious white smoke coming up from the bottom of the crater. The vent water has a temperature of 112°C. We collect plenty of samples of the hot vent fluid and rocks. QUEST has scoop nets in one of its drawer that we use to scoop up animals from dense beds of mussels.

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In the evening hours, the ROV is brought back on deck and the scientists have plenty of water, rock, and biota samples to keep them working in the ship’s laboratories for most of the night.

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Bernhard Schnetger from the Institute for Chemistry and Biology of the Marine Environment in Oldenburg examines the water samples QUEST has retrieved for radium isotopes, of which there are four with different half-lives and decay products. One of these isotopes has a half-life of 4 days, meaning it takes only that much time to halve the number of radium atoms in a sample. The radium isotope with the longest half-life decays much more slowly, requiring 1600 years for the number of atoms of that isotope to be reduced by half.

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Like many other elements, radium is present in hot magmatic rocks deep inside the volcano. Seawater circulating along fractures within a volcano leaches radium from the volcanic rocks and flushes it into the ocean. “Using isotopes I can find out how much of the radium was released from the hydrothermal vents and how quickly the hydrothermal vent fluids and ambient seawater were mixed. This helps me figuring out the effect of hydrothermal vents on ocean composition,” says Bernhard Schnetger.  

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With the manipulator arms of the ROV we can collect biological samples, like mussels. Christian Borowski from the Max-Planck-Institute of Marine Microbiology studies symbiotic organisms, specifically invertebrates like mussels and tube worms, which live in a symbiotic relationship with bacteria. The gills of these animals host countless bacteria that make a living from chemosynthesis.  
Bild: MARUM – Zentrum für Marine Umweltwissenschaften, Universität Bremen

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“Just like in photosynthesis, chemosynthesis turns inorganic carbon dissolved in seawater into organic molecules: biomass at the base of the hydrothermal food chain. Light is not needed in chemosynthesis, as the energy for the metabolism comes from chemical reactions,” says Christian Borowski.

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Because there is no light at water depths greater than 200m, photosynthesis does not play a role in the deep sea. At hydrothermal vents, bacteria react hydrogen sulfide with oxygen and use the energy released to turn dissolved carbon dioxide into organic molecules, which support their host animals. The benefit for the bacteria in this symbiotic relationship is that the host animal pumps water through the gills and delivers oxygen and hydrogen sulfide to the bacteria in the gill tissue.

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This morning, the ROV QUEST was once more deployed over the volcanic caldera. The console from which QUEST is controlled is housed in a shipping container on the main deck. The ROV‘s first mission today is to collect the heat flow blankets, which are recording how much heat is being transferred from the flanks of the volcano into the ocean. On computer monitors, we can watch how QUEST is searching the sea bottom for the blankets. Exactly at the moment we’re all looking at the screen, a shark shoots through our picture, unimpressed by our robot. QUEST picks up the blanket with one of its manipulator arms and places it into a drawer in its body.

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Just when the ROV was about to surface and all the scientists were ready to secure their samples, someone shouts out “Dolphins!”. We all race to the railing to inspect these marine mammals.

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A large school of dozens of dolphins plays in the water just behind the tail of the ship. It is fascinating to see groups of dolphins emerge from and plunge back into the water in perfect synchrony.

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Water geochemists Charlotte Kleint, Nico Fröhberg, and Jan Hartmann can finalize their measurements of hot water for the first work area of Macauley Cone. With the CTD, they collect additional samples of the remote parts of the hydrothermal plume, where the dilution with seawater is greatest.

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After another successful dive, QUEST surfaces with abundant sample material. The scientists quickly move the samples into the various labs and start describing, subsampling, measuring, and archiving the samples. Properly archiving and preserving the samples is key, because many of the measurements cannot be conducted at sea but will take place in the different home laboratories. This work will keep the scientists busy for months if not years. Only through meticulous scientific work, however, will we be able to use the data and observations collected to improve our understanding of the oceans.

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Today’s dive of QUEST to a smaller volcano yielded an impressive catch: mussels of the species Gigantidas gladius with a length of up to 30 centimeters. The same species was sampled at Macauley Cone the day before, but there the animals were much smaller (<6 cm long). “This indicates that we sampled a population of old mussels today, while we found only young animals yesterday. The large numbers of very large shells of dead mussels at Macauley Cone suggests that old mussels once proliferated there, too,” explains Christian Borowski.  
Gigantidas gladius does not live in the immediate vicinity of vents, but prefers areas where lukewarm water, which results from mixing of seawater and vent fluids underneath the seafloor, seeps up. The biologists suspect that this seepage may gradually stop in some areas, while new seepage patches develop elsewhere. New seeps then attract mussel larvae to colonize the area and new mussel beds will grow.  

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Today is our last day at Macauley Island. Two days ago QUEST found evidence for a – so far unknown – black smoker at the seafloor. Using the CTD, we found another plume from an unknown source which we will attempt to find on today’s dive.  

 Whoever discovers a hydrothermal vent is allowed to name it. Unlike the names of flora and fauna, there are no strict rules for naming hydrothermak vents. Commonly their names refer to features of the vent’s geology or to their discovery. There is even a hydrothermal vent called Barad Dûr (after the tower in the Lord of the Rings) on the Mid-Atlantic Ridge.   Should we find a new black smoker on the expedition, we can name it. However, we have not agreed on a name so far.  

 Picture: MARUM – Centre for Marine Environmental Sciences, University of Bremen

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Cornel de Ronde has discovered two hydrothermal vents on past expeditions and named them after his daughters Olivia and Lena. His second-oldest daughter, Lena, is particularly proud that her vent has a gold content of 90 gram per ton, while Olivia’s vent contains only copper. Cornal de Ronde’s youngest daughter Scarlett is five and keeps asking for her own vent: “Daddy, I want a smoker too!”   Picture: NOAA        

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Unfortunately, our search for the second hot source on the submarine volcano offshore of Macauely Island remains unsuccessful. And now the time has come to leave our first working area. Since birds from the island were attracted by the light of the ship, especially during the night, and some of them have landed on the vessel, we searched for stowaways in all corners of the ship. The New Zealand authorities specifically emphasized how important it is that we leave the birds on the island and release them from the ship before we leave the area. And the crew does discover a lost bird in the winch room, which is set free before we set sail again. The picture shows a red-billed tropical bird which can be recognized by its long red tail feathers. For the first time since we cameon board, there is a small rainshower.

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In the evening, we look forward to a special event: we are making a short detour to Curtis Island, a ragged volcanic crater emerging above the sea surface. Directly next to it is the even smaller rocky island, Cheeseman Island. A smell of rotten eggs whiffs over from both islands, a clear indication that the volcano is emitting hydrogen sulphide.

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Volker Ratmeyer, chief of the ROV team from MARUM, pilots a drone over the water towards the islands. It sends us videos in real-time from the volcanic crater, in which lies a small lake. During the flight the drone also takes fantastic pictures in a bird’s eye view from the Sonne.  ‘Bird’ is an apropos term: three individuals of a shearwater species escort the drone during its flight. Finally, we begin our 15-hour transit to our next working area, Haungaroa. We will see no more land from now until we reach Auckland on January 21st.

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On New Year’s Eve, the cooks excelled themselves the the barbecue: we had roast suckling pig, various salads and vegetarian grilled dishes – we could not have imagined anything better in our dreams. And, of course, we watched “Dinner for One” at 9 p.m., a German tradition on New Year’s Eve but a first for our American, French, and New Zealand colleagues.

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12 hours before German time, we welcomed the New Year with sparkling wine and sparklers. We wish all of you a wonderful year in 2017!

Video: René Neuholz

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This morning at 8 o’clock, when many of you in Germany were probably just enjoying some raclette or fondue and the first firecrackers were being ignited, the ROV QUEST descended on its fifth dive, also the first dive at the Haungaroa volcano.

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During the dive, we are looking for the signals of a hydrothermal plume above the crater, which was recorded by another ship expedition fourteen years ago. And, indeed, the ROV landed in the middle of a field with diffuse warm fluids when it reached the rim of the volcanic crater at a depth of 670 m . The temperature here is around 23 degrees C, while the temperature of the ambient seawater is 8 degrees. The living environment here spills over with animals: it abounds with barnacles, tube worms, lobsters, mussels, fishes, shrimps, anemones and snails. We also find the mussel Gigantidas gladius again, which grows up to 30 cm long. Against the dark background, fluffy looking bacterial mats glow in the searchlights.

Picture: MARUM – Center for Marine Environmental Sciences, University of Bremen

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In the area of about two hundred meters square we come again and again across so-called ‘shimmering water’. When warmer water from the subsurface mixes with colder ambient water, this forms flow marks. The water resembles air flickering from heat. This gas-bearing shimmering water is what supports life in the hydrothermal field.
 Picture: MARUM – Center for Marine Environmental Sciences, University of Bremen

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QUEST takes samples of the shimmering water, as well as sampleing volcanic ash and other rocks. It scrapes off iron crusts which have formed on top of the ash layers. The bio box is filled with mussels. The heat flow blankets are deployed again here, and will be collected again tomorrow.

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“Often the search for hydrothermal fields is like looking for a needle in a haystack. It is great that we landed directly in this hydrothermal field with the ROV today. Even though the vents here are very diffuse, we can assume that simply because of the large surface of this active area there is a significant amount of material flux into the surrounding water.” Andrea Koschinsky is pleased about this finding. The scientists once again have a full night program in the eleven laboratories.

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The weather forecast announces a low-pressure area for Thursday and Friday, which will pass by the east coast of New Zealand and will gift us with high waves. For our working area, waves up to four to five meters high are predicted. “We have only three and a half meters of freeboard, which means that with a wave of four meters, water could enter the main deck,” says Captain Lutz Mallon. “We also need to determine whether the ROV and the CTD can still be deployed, or whether we can only map the seafloor under these conditions.”

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Throughout New Year’s Eve, we mapped the seafloor to fill in gaps in older maps of the seafloor. RV Sonne is equipped with the most globally up-to-date swath echosounder. With this device, it can produce high-resolution maps of the seafloor even at a speed of up to 10 knots. Depending on the water depth, about once per second a shrill whistling signal with a frequency of 12 kilohertz is beamed. The signal is reflected off the seafloor and is then recorded by the hydrophones installed underneath the ship’s hull. On the sea surface, the sound velocity is 1524 meters per second. The crater of Haungaroa volcano is at a water depth of 650 m. Therefore, the sound signal takes a bit less than a second to reach the bottom from the ship and then return again.

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With the echosounder we cannot only map the seafloor, but we also detect gas bubbles. Because of the difference in density between gas and water, the sound signal is also reflected by gas bubbles, which occur as green spots on the blue background of the monitor. Last night, marine geologist Janis Thal discovered such a gas bubble flare above a volcanic cone in the caldera of Haungaroa. Today, the ROV QUEST followed this indicator, looking for a hydrothermal source. And indeed, it descended into the thick of a field of chimneys from which 230 degrees C hot water is being expelled.

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We took samples of the hot fluids emanating from the chimneys with the ROV and collected fragments of the chimneys. It was a very special moment when Harald Strauß lifted the chimney from the ROV drawer, which we so far had only seen in the videos of the underwater world.

Picture: MARUM – Center for Marine Environmental Sciences, University of Bremen

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In addition to the chimney, QUEST brought biological, water, and rock samples to the Sonne, which again promise a long night in the lab and subsequently material for many years of study.  

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Two more CTD stations are planned for tonight. For the so-called tow-yo, the CTD moves up and down like a yo-yo while the vessel pulls it along a track over the underwater volcano. From this zig-zag line, we can find out where the plume is strongest and where we could perhaps find more hydrothermal sources. The second deployment is a simple vertical one, during which water samples are taken about the newly discovered chimney field.

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Last night’s tow-yo went very well, and the turbidity and the redox potential measured with the CTD gave indications of other hydrothermal vent sites on the caldera floor of the volcano at a water depth of about 1100 m. Janis Thal’s echosounder data showed gas emissions at the same site. Tomorrow we will dive down there with QUEST to get to the bottom of these hydrothermal signatures. Today we are taking further samples at the hot vents we had discovered yesterday, and collecting the heat flow blankets.

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The picture does not really show a snowy submarine Christmas tree, but instead a rock covered with barnacles, the closest thing to a Christmas tree of everything we have seen during this cruise so far. “Goose barnacles, like bay barnacles, are crustaceans which sit firmly on the rocks of the seafloor and filter nutrients from the seawater,” explains biologist Katharina Sass from the University of Hamburg. Picture: MARUM – Center for Marine Environmental Sciences, University of Bremen

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Goose barnacles cling on to the rock with an adhesive disk. Their heads sit on a stipe and consist of several plates made of chitin. Between these chitin plates, they poke out their fan-shaped twine feet, with which they filter plankton from the water flowing by. On their twine feet there are numerous white bacteria, which give the animals their feathery-fluffy appearance.

 Picture: MARUM – Center for Marine Environmental Sciences, University of Bremen

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Despite the clear indication of more hydrothermal vents in the crater of the volcano, we can’t find anything. With visibility at around 15 meters and an area of approximately a square kilometre in which the vents may be located, we could well have passed them without noticing.

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We are now on our way from Haungaroa to Brothers Volcano. We are using the transit for a meeting, where every working group is presenting their results so far. We have already learned that Macauley cone has one of the most acidic, and in the shallower hydrothermal systems most iron rich, fluids. We measured a pH of 1.1,as acidic as battery acid. We also found a lot of sulfur. It seems as if at Macauley, boiling brine is emitted from vents on the seafloor, which has been heated underground.  

“We knows this because the salt concentration in these solutions is extremely high. During boiling, a vapour phase must have separated from this salt-rich phase, which was left behind,” explains Andrea Koschinsky.   Correspondingly, at Haungaroa volcano we find the vapour that separated from the brine. At 686m depth the boiling point of seawater is 270°C, which is exactly what we measured with the ROV’sthermometer. “That is exactly what we were hoping for: sulfuric acid fluids at one volcano, carbonic acid-rich solutions at the next,” Wolfgang Bach explains ,evidently enthralled  with both sites. “ With a pH of 4, the fluids at Haungaroa volcano were a thousand times less acidic than those at Macauley volcano,” Andrea Koschinsky adds. With the heat flow blankets, we measured a huge amount of heat being released from the volcano flanks into the seawater.

The biologists are also reporting some observations on the age of the different mussel populations, when Fabio Caratori Tonini enters the room with a small ivory-coloured object….

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The tooth marks on the magnetometer sensor are some millimetres deep. Fabio Caratori Tontini presents the broken off shark tooth he pulled out of the sensor. The one centimetre thick acrylic glass housing of the sensor is covered with multiple cracks and a small piece of a shark tooth is still sticking in the surface. The fins of the torpedo shaped sensor have also fallen victim to the shark attack. The geophysicist reports, surprised, that the sensor has been attacked several times by sharks, “but today’s attack was much more powerful”. His colleague Cornel de Ronde agrees and suspects that we were close to getting water into the precious electronic sensors.

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Shark attacks on magnetometers are quite frequent because the animals can feel the magnetic field the magnetometer is producing. Sharks have very sensitive sensory organs in their nose called the ‘Lorenzian ampules’, which they use to detect the electric field of their prey. Quite possibly, the shark has mistaken our magnetometer for food. Despite all the expertise present on board, we have no shark expert present, and therefore we can only suspect that it might have been a great white shark. Interestingly, even today it is unknown if humans are able to sense magnetism or not.    

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With the magnetometer, Fabio Caratori Tontini can measure how magnetic the sea floor is and if it consists of more magnetic volcanic rock or if we are just moving over sediments that are only weakly magnetised. By measuring the magnetic field, the scientist, who is from the New Zealand research institute GNS Science, can also determine the age of the rocks on the seabed. Usually the magnetization of the Earth reverses itself approximately every 250,000 years. The rocks record the direction of the magnetic field at the time they cooled down. After each pole reversal, the magnetic field of the rocky sea floor points in the opposite direction. The different layers tell the geophysicists also how many hundreds of thousands of years old the rocks are. The last polar reversal happened 800,000 years ago - the next one is long overdue.

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Geologists Wolfgang Bach and Harald Strauß cut the chimneys with a stone saw to study their interior.

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Wolfgang Bach cuts our first chimney lengthwise. The electric stone saw goes through the flue like it’s butter.

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After Fabio Caratori-Tontini fixed the magnetometer yesterday afternoon with glue and new fins have been attached, it can be used again tonight to record the magnetic fields on the bottom of the sea. At the same time we are mapping the sea floor on our way to Brothers Volcano.

 At 8 a.m. the ROV is deployed again, and one hour later it arrives on the sea floor 1450 metres below.

“My personal highlight today was the snow covered landscape,” remarks Andrea Koschinsky. And indeed the underwater pictures transmitted by the ROV look like a snow covered forest clearing. “The colours down here have a blue shift because it is deeper, and the light sediments sparkle white like fresh snow,” the chief scientist continues. “The shrimp gliding through the water look, in the spotlight, like large snowflakes.”  

 In the evening the ROV brings rocks and a sample of sulfur on board and “many water samples that smell like rotten eggs,” according to Andrea Koschinsky.

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We spend most of the dive deploying the heat flow blankets and exploring the larger of the two cones in the volcano caldera. For the first time we don’t find any mussels, but see only swarms of shrimp on the seafloor, which flee as soon as the ROV approaches. In the afternoon, we suddenly encounter previously unknown hydrothermal vents at Brothers Volcano. Located at a depth of 1200 meters, the fluids exhibit a relatively acidic pH of 2.1. We take water samples and sample of iron crusts.

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It is windy today, and the currents around Brothers Volcano are too strong for the ROV to be deployed. The alternative program is to go to the undersea volcano Kibblewhite. It is located about 30 kilometres north-west at a depth of about one kilometre below the sea surface. Our echo sounder has shown that there are two volcanic craters. We start off with a tow-yo using the CTD to see if there are hydrothermal vents we could target during future expeditions. In the evening we steam back to Brothers Volcano, where hopefully we will be able to go diving again tomorrow to take samples of hot fluids and recover the heat flow blankets.

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Today, for the first time we saw another ship on the horizon. The huge container ship “Hamburg Sud”passed us slowly.

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This afternoon, a giant black-and-white bird majestically circled around the ship. „That was an albatross,” says Nico Fröhberg. “Albatrosses are pelagic birds that spend their entire life migrating across the oceans. Through a tube in their beaks, they manage to excrete the accumulated salt.”

“It didn’t flap its wings even once while I was watching it,”reports Charlotte Kleint in amazement.

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During a tour of the engine room, chief engineer Achim Schüler explains how SONNE is setting new standards: The noise and vibrations coming from the engines are reduced to a minimum. All the engines have anti-vibration mounts, ensuring that almost no vibrations are transmitted to the hull. This also means that the people on board barely notice the 6,500 kilowatts of diesel power working beneath their feet.

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The research vessel SONNE is built following the “safe return to port“ principle: even in case of severe damage – for example a fire in the engine room – it is possible to reach the next port thanks to the second engine room. Achim Schüler explains: “Fire is the worst case scenario for any ship.” SONNE is also resistant to collisions, inrush of water, and seafloor contact: “As inrush of water in both engine rooms is highly unlikely, we can go to sea feeling very calm.”

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All diesel tanks hold a total of 1080 cubic meter which equals 1.080.000 1-Liter bottles of water. “The ship can go at full speed for an entire month with that amount of fuel” explains Achim Schüler. However, this never happens, since scientists tend to stay within their working area in between.

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The vessel is also leading the pack when it comes to environmental protection: The exhaust systems were designed in line with Blue Angel certification requirements. It is not only that the vessel uses ultra-low-sulfur diesel fuel, but also that its exhaust gases are scrubbed in order to remove nitrogen oxide so as to keep emissions as low as possible.

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The pilots navigate the ROV through difficult environments such as the pillars and chimneys at Brothers Volcano. The job of an ROV pilot is a complex one: they have to be highly skilled and highly trained in order to fight currents whilst navigating through complex structures.

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Despite strong currents near the seafloor we had two successful dives: “we see what you could call forests of chimneys”, Andrea Koschinsky says excitedly. “Furthermore, delicate pillars with smoking heads which resemble beehives. Some of them look as if they were painted completely in green”, she explains. The light-greenish shimmer is caused by mats of bacteria which oxidize iron and sulfur on the surface of these beehive-structures.   The surface below the bacteria is auburn colored. By grabbing a piece with the robots arm, we discover that the delicate pillars are more stable than they look. “They are stable, because their interior is composed of chalcopyrite”, explains Wolfgang Bach. As we collect the ROVs loot in the evening, we discover orange shining chimneys. Their interior sparkles reddish-gold in the sunset.

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Lucy Stewart works as a postdoc in the New Zealand research institute GNS Science. The microbiologist specialises in microorganisms which live in hot springs and hydrothermal vents. At hydrothermal vents, gases, sulphur, and metals are released into the sea, “much more than in the rest of the oceans,” Lucy says. She is especially interested in autotrophic microbes. Autotrophs are organisms which can obtain the energy that they need to live from inorganic molecules like sulphur and hydrogen. The microbiologist is fascinated by how the living world interacts with geology. “Two and a half billion years ago, there was almost no free oxygen on Earth. At some point living organisms began to make oxygen through photosynthesis. We can see this in ancient rocks because suddenly at this time oxidised iron, or rust, begins to appear.”

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With her current project she would like to find out which warmth-loving or ‘thermophilic’ microbes are present in the waters and on the islands near New Zealand. She is looking for bacteria and archaea which live in hot water, at temperatures above fifty degrees Celsius. They are present in hot springs on the Kermadec islands of Raoul Island and Curtis Island, and also on the active volcanic island White Island, close to New Zealand. These thermophilic microbes are able to make a home for themselves in the warm rocks surrounding underwater volcanoes. When seawater is drawn into the rocks and then released back into the ocean, it carries the microbes with it. Lucy takes her water samples from these diffuse fluids near hydrothermal vents.

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In her laboratory on the ship she uses an oven to incubate bacteria at seventy degrees Celsius. To figure out if the bacteria are using iron or sulphur to support themselves, she incubates them with each element. In her home laboratory, she will extract the DNA from the bacteria to find out which species they are.  

“In New Zealand environmental conservation is a sadly important topic and many people are worried about the birds, lizards, and plants which live here. Similarly, we also have a diverse range of microorganisms, many of which are probably unique, but we pay them very little attention.”

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Andrea Koschinsky is the chief scientist of cruise SO253. Together with other organisers, she proposed this cruise to the BMBF and coordinates the different scientific activities. She organised the cruise in communication with the Control Station for German Research Vessels, the shipping company Briese, the Master of the RV Sonne, and New Zealand authorities. This includes the technical requirements for the cruise, such as which pieces of equipment are available on board and which equipment scientists would need to bring themselves. About 6 months before the cruise, she applied for permission to carry out scientific work in the Kermadec volcanic arc via the Office of Foreign Affairs. During the cruise she coordinates the complex research program, including the deployment of the various devices, and acts as the interface between scientists and the ship’s leadership.

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Dr Koschinsky‘s research focus is the impact of hydrothermal fluids on the trace element budget of the oceans. “We track how chemical elements, especially trace metals from hydrothermal vents, mix with ambient seawater and are dispersed in the ocean. We want to find out how much of the hydrothermal element input settles again in the vicinity of the hydrothermal vents, and how much is transported into the open ocean where it can contribute to the biogeochemical cycles. For these processes, iron plays a key role because as a micro-nutrient it is often the limiting factor for plankton growth in surface waters. If hydrothermal iron is being transported up into the upper water layers, this would mean that hydrothermal processes on the seafloor have a direct impact on life in the upper water column of the ocean.”

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Dr Koschinsky is a marine geochemist. She teaches and conducts research at Jacobs University Bremen. Since her first research cruise as a PhD student in 1990, she has sailed on every ocean in the world. Her research looks at trace metals in different marine systems and investigates their interactions with biological processes. “During a previous research cruise, for example, we studied how mussels at hydrothermal vent sites deal with the high load of trace metals. We found that these mussels often store large quantities of heavy metals in their tissues, such as the gills and digestive gland, without being harmed by them. Furthermore, we found that hydrothermally-associated microbes are able to detoxify copper by excreting organic molecules that bind to it.”

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Benedikt Geier is a PhD student in the Symbiosis Department at the Max Planck Institute for Marine Microbiology in Bremen. His research focuses on the symbiotic association between deep-sea mussels and chemosynthetic bacteria. These bacteria are located in the gills of the mussels and benefit from the constant flow of nutrients generated by the mussels through filtration. The mussels, in return, feed on the metabolic waste products of the bacteria.

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Benedikt uses a combination of microscopic imaging techniques to determine which molecules come from the bacteria and are beneficial for the mussels. By locating the symbiotic bacteria in the mussel gills and comparing these images with images of molecule distributions, he can see which molecules are produced by the bacteria and which by the mussels. in this way, he tries to understand how these close associations between symbiotic organisms in the deep-sea function.

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Wolfgang Bach is petrologist in the Department of Geosciences of the University of Bremen. Petrologists study how rocks come about and how they interact with their surrounding. WB investigates how rock form, for instance in volcanic eruptions or when tectonic plates collide and mountain ranges form. 

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During expedition SO253, he investigates the interactions between seawater and rocks. The seafloor continuously has seawater flow down into the oceanic crust to be expelled in hot springs. In the volcanic Kermadec Arc, the intensity of the chemical exchange between circulating seawater and rocks is particularly intense: “The volcanos spit out carbon dioxide and sulfur dioxide. The latter reacts with water to form sulfuric acid and sulfur. We have collected samples of native sulfur directly from hot sulfuric acid springs. In the pores of the sample, one can find minerals that have formed from the emitted volcanic gas.” Wolfgang Bach does not only collect rock samples with the ROV QUEST but also samples the hot vent solutions: “Like a forensic scientist, we can figure out what is happening deep inside the volcano by reading the message encoded in the chemical and isotopic composition of the solutions.” A challenge in sampling the vent solutions is keeping the large amounts of dissolved gas from bubbling out during ascent of the ROV. This is why the petrologists onboard SONNE use a special sampler with thick walls of steel that can hold a pressure of 400 bar. This pressure corresponds to a depth of 4000 m in the oceans.

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Wolfgang Bach can also answer the question why seawater is salty: When rainwater trickles into the rocky ground, it dissolved part of the rock. That water is eventually discharged into the oceans by rivers. The sunlight has the water part of those solutions turned into vapor; the salty part remains in the oceans. The vapor condenses into rain water and a new cycle begins. Circulation of seawater within the oceanic crust also affects the composition of our oceans. But this does not have the oceans get saltier with time! This is because the seafloor constitutes a sink for many elements: magnesium, potassium, and carbon, for instance, are stored within the ocean crust to depths of many kilometers.

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Valerie Stucker manages the marine geochemistry laboratory at the New Zealand research institute GNS Science in Wellington. She is responsible for fluid chemistry and analysing the composition of water samples from the Kermadec volcanic arc and hot springs in the North Island of New Zealand. “These hot fluids tell us a lot about what’s happening underground. We can say, for example, which interactions have occurred in the subsurface between the water and rocks, by measuring dissolved minerals,” she explains.

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 On cruise SO253, Valerie takes samples with a titanium major sampler. If the ROV has found a hydrothermal vent, it picks up the sampler with its manipulator arm from a storage container the front of the ROV. “I look for the hottest fluids we can sample. The best samples are those that haven’t been mixed too much with seawater. To make sure we achieve this, we stick the snorkel of the sampler as far as we can into the vent outflow,” says the chemist.

At this moment Cornel de Ronde enters and tells us that the ROV has found hydrothermal vents at Brothers Volcano. On the TV monitor we see thick clouds of smoke from the vents on the ocean floor. Valerie has to hurry to the ROV container to supervise sampling with the titanium majors. “I will oversee the sampling and make sure the samplers are working properly,” she explains as she leaves.

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When Valerie is not working on board, she spends her free time training for her hobby, handstands and acrobatics. “Unfortunately, it’s really difficult to do handstands with all the ship movement, so I have been doing more headstands,” Valerie says. She really enjoyed the New Year’s celebrations on board. “It was lovely that we could all get together as a group, since there wasn’t any sampling that day. It made New Year’s Eve special, since we couldn’t spend it at home with our families and friends.”  

Christmas was also exciting on board for the chemist. “On Christmas Day we passed one of the Kermadec Islands, Raoul Island, which was like a special Christmas present for me, because it‘s one of my favourite places in the whole world,” she says excitedly. Few people make it to the remote island, and the seven people who live there rarely have visitors. In April the scientist visited there for four days. “It was one of the most wonderful places I’ve ever been. The island is a volcano and it’s covered with trees and tropical plants with beautiful beaches. If you stand on the rim and look down into the crater, you can see Blue Lake and Green Lake,” she describes.

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Sylvia Sander is a research associate professor at the University of Otago on New Zealand’s South Island. Born and bred in south-west Germany, she has lived and worked for the last 15 years in New Zealand. In-between, she lived in the Netherlands. “For me it was too crowded there – I wanted to live in a less populated country,” says the chemist, grinning, about her new home country. As a marine chemist, she studies the distribution and form in which heavy metals are present in the ocean. ”For example, iron occurs in different size fractions, truly dissolved, as buoyant nanoparticles, and as particles which are large enough to sink to the seafloor,“ she explains. ”Additionally, there are different chemical forms of iron. The majority of dissolved iron atoms form compounds with carbon-rich molecules. Since free iron is very insoluble in seawater, even more of the dissolved iron would otherwise form particles large enough to sink.” Iron is important in the sea, she explains. “Iron is an essential micro nutrient for all living organisms on Earth – if there is not enough iron available, phytoplankton won’t grow. Phytoplankton is the basis of the entire marine food web. Additionally, carbon dioxide is taken up by phytoplankton during photosynthesis and under certain conditions this CO2-carbon can be buried in the sea floor. So phytoplankton and iron have the capacity to influence our climate.”

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„On this expedition we are trying to understand how iron from hydrothermal vents is transported into the open ocean,“ says Sylvia Sander. The iron concentration in hot vents is about one million times higher than that in the open ocean. “As soon as the iron is released into the cold, oxygen rich seawater most of it becomes insoluble and precipitates. It can form these iron crusts we saw today at Brothers Volcano,” she continues. ”Until recently it was assumed that all hydrothermal iron is removed from the seawater close to the vent site and does not reach far into the surrounding seawater. Today, however, we know that hydrothermal iron plumes can be transported horizontally over thousands of kilometres.” Most hydrothermal vents are several thousand meters deep. The iron rich plume usually does not rise to the surface. Sylvia Sander describes her research aim during this expedition: “Here at the Kermadec Arc, some of the vents are shallow enough that the iron plume can reach right into the upper water layers, where phytoplankton lives. We would like to understand how much iron is actually reaching the photic zone.”

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A 20-year long collaboration and friendship connects her with the chief scientist, Andrea Koschinsky. “Actually, I became a marine scientist because of Andrea. She wanted to use an analytical method I developed during my PhD. We met and she offered me the opportunity to join a hydrothermal cruise to the North Fiji basin“ Sylvia Sander remembers from her first expedition. “What impressed me most during that first cruise was the multidisciplinarity: geologists, biologists, and chemists, all working on one common goal. We spend four weeks together on the ship and inevitably you learn a lot about the research of other participants. It opens your horizons and you pick up a lot from other research areas.“

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Cornel de Ronde is a geologist at GNS Science, a New Zealand research institute. He leads the marine minerals group there, studying how copper, zinc, gold, silver, and lead crystallise from hot fluids. His main study area is the Kermadec volcanic arc directly to the north of New Zealand, where these metals most frequently occur in hydrothermal systems. “It all comes down to the temperature: the hotter the fluids, the more metals are transported within them, such as copper and gold,” the New Zealander explains. The water, in the deep sea a kilometre and a half down, starts to boil at around 345 degrees Celsius.  In shallower depths the water is already boiling at lower temperatures, so it can’t get as hot. “To find copper, we have to look for very hot vents, with temperatures reaching at least 270 degrees.”

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"If we find large deposits of copper and gold right on our front doorstep here in New Zealand, I’m interested as a scientist to figure out how these metals are transported out of the cores of volcanoes. We also study their composition, so we can estimate which raw materials they contain,” he continues. “We have to decide if these deposits are really going to be mined or not.”  

The New Zealander has studied volcanic arcs all over the world and would like to use his research to come up with solutions to some of the greatest problems of our time. “The solutions for these problems – energy, food, and minerals – lies in the oceans,” he is convinced.

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“My personal highlight for this research cruise has been diving at Haungaroa. There, we were following a signal that Sharon Walker and I measured fourteen years ago at this site. At that time we had a CTD to measure hydrothermal plume signals with, but unfortunately no ROV,” the New Zealander reminisces. Sharon Walker, who is also a participant on our cruise, met Cornel in 1994 on his first research voyage with an American ship on the East Pacific Rise.  

“Discovering new things is, for me, still a really special thing. I love science a lot, but I wouldn’t be a scientist if there wasn’t so much adventure and fun in it,” Cornel says. “The greatest pleasure of it for me is doing public lectures and bringing these marvels to my audience. That’s when it really becomes clear to me how out of the ordinary it is, what I get to see and experience on these research expeditions.” We also get the chance to see Cornel’s skills as an entertainer on this trip, as soon as he sits down in the ROV control container and provides colourful and knowledgeable commentary on the pictures from the underwater camera.

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Charlotte Kleint, Jan Hartmann and Nico Fröhberg are geochemists working with a team from Jacobs University Bremen. On this cruise, they are taking samples of hot hydrothermal fluids at different distances from the original hot source. 

Using the ROV QUEST, they dive as close as possible to the vent outlet to take fluid samples with a titanium nozzle directly at the point of discharge into the surrounding ocean. Additionally, QUEST takes samples in the rising hydrothermal plume, where fluids mix with seawater with increasing distance from their source. As soon as the fluid has mixed with enough seawater to have the same density, it does not rise further towards the sea surface but is instead transported horizontally by ocean currents. With a CTD probe, which detects turbidity, they can measure the extent of the plume at greater distances. “We follow the fate of the fluids in the ocean, so to speak,” explains PhD student Jan Hartmann. Jan is a PhD student at the University of Heidelberg and is supporting the fluid chemists working under Andrea Koschinsky as a guest scientist.

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With an initial chemical characterization on board the ship, the fluid chemists can already tell a lot about the properties and formation of these hot solutions. “We see an increased chloride content in our samples. Chloride is the main component of sea salt, so our sample represents a salty brine formed by boiling fluids. We have also found that our samples to date are extremely acidic, with pH values below 2 – more acidic than gastric acid or Coke!” explains Jan Hartmann. “These acidic fluids dissolve portions of  the rocks below the seafloor, which we can see in the increased magnesium content of the fluids,” adds Nico Fröhberg. Nico is writing his Bachelor´s thesis at Jacobs University about the  chemical characterization of these extraordinary hydrothermal fluids.

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Rebecca Zitoun is a PhD candidate at the University of Otago in New Zealand. Her work includes the quantification of copper concentrations in different marine environments, specifically determining its toxicity thresholds for mussels and other marine organisms. “In the water column, all metals are present in different chemical forms. Copper is mostly present in the water column bound strongly to other molecules. In this form, it’s less detrimental to organisms. Only free copper ions and/or weakly bound copper are acutely poisonous in smal amounts.”

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Every country has their own threshold values for how much copper is allowed to be present in the water. These values are critical for the health of the oceanic ecosystem as well as for aquacultures. “To date, most studies of copper stress in the aquatic environment only look at the total copper in the system, which is easier and less time consuming to measure, but does not reflect the actual metal toxicity marine organisms are potentially exposed to. I am quantifying not only the total amount of copper but also measuring the concentrations of free and weakly-bound copper in the water column. With my research, I will be able to show whether free copper ions are key drivers of ecosytem health and function.“ Rebecca Zitoun hopes that her studies will be used when creating future water quality standards for marine environments.

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On the cruise, Rebecca Zitoun will be sampling hot hydrothermal fluids and analysing the ratio of strong to weakly bound copper in them. “I expect that here in the sampling area, copper is predominantly strongly complexed. Normally the copper concentrations around hot vents are so high that if the copper was in its free or weakly-bound forms, the survival of organisms living nearby would be highly constrained. In reality, however, hydrothermal vent areas flourish with life.“

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Harald Strauss is a geochemist at the University of Münster. He is reporting about his cruise on the Sonne on a blog on the university website.

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During this research cruise to the submarine hydrothermal vents along the Kermadec volcanic arc, he will be investigating the sulfur-rich vent fluids and how these contribute to the sulfur budget of the ocean.

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Marie Heidenreich is science journalist and writes this blog. She is responsible for all the public outreach activities of SONNE cruise SO253. Marie has studied Life Science and Cultural Anthropology and works for Project Management Juelich. 

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Maren Walter works as a scientist at the Institute for Environmental Physics and the MARUM Center for Marine Environmental Sciences at the University of Bremen. As a physical oceanographer she studies waves, not the ones at the sea surface but the internal waves in the interior of the ocean. "I am interested how these small scale processes influence the large scale circulation ad stratification of the ocean."

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During the expedition SO253 she looks into the dispersal of water and other output from the hydrothermal vents into the ocean. "We observe the currents and the stratification in the water and use these information to determine vertical mixing", the researcher explains. "The stratification of the ocean depends on the temperature, salinity and the pressure. These quantities are measured with the CTD sonde." CTD is the abbreviation for Conductivity, Temperature und Depth. Attached to the CTD frame are two current meters, the so-called ADCPs, that measure the speed and direction of the currents using underwater sound.   Although she participated in her first research cruise as a student in 1994 and took part in 23 cruises since then, she this one is still a first for her: "Until now I have worked on mid-oceanic ridges", the physicists reports, "studying underwater volcanoes is new to me - we have to be very careful using our instruments in the steep craters. Just now we have navigated a towed CTD around a 90m high pillar in the Rumble III crater."

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Her life as a marine scientist fulfils a lifelong dream for Maren: "As a child I always wanted to go to sea, following the footsteps of my father, who was a captain. During my studies of physics I then learned that I can reconcile doing natural sciences and sea travel by becoming an oceanographer, so I took up physical oceanography in Kiel. I love going to sea and being part of a team of researchers from various disciplines that works towards understanding the system Earth."

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René Neuholz is a PhD candidate at the Institute for Chemistry and Biology of the Marine Environment at the University of Oldenburg. He studies the dispersal of water from hydrothermal vents by using the radioactive element radium. Radium occurs naturally in every rock on earth, as it is generated by uranium decay. Large amounts of radium are present in the seafloor. If seawater infiltrates into the sediment, it dissolves radium from the rocky material. Deep in the oceanic crust, the water gets heated up and is finally released through hydrothermal vents, carrying the dissolved radium with it.

“We are collecting a hot and undiluted fluid sample. The hydrothermal system of Macauly showed pretty high concentrations of radium.”, said René excitedly. “We are also sampling the water column at different distances from the hydrothermal vents and we can see that the radium concentration decreases with distance. The reason is firstly that the hydrothermal fluid gets quickly diluted, and secondly the radioactive decay of the radium. As we are know the speed of decay, it is possible to calculate the age of the samples. Finally, we hope to be able to say that ‘to travel a distance of 500 meters, the hydrothermal fluids need a certain amount of time’. With that, we won´t just know the age of the sample, we will also know the transport velocity of the hydrothermal fluids,” he continues.

“Tracing fluxes of water with radium is a very practical concept for marine sciences, as this method uses an element which is already present in the water. “ If flow velocities of smaller rivers need to be determined, often saltwater is introduced as a tracer on one point and the travel time of the saltwater is measured over some distance. In the deep sea colored fluid is used to visualize water filtration by sponges. We are using an element that occurs naturally in the water.”

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Andreas Türke works as a postdoc at the University of Bremen, Germany. He analyzes the distribution of chemicals in the water column that are released from hydrothermal vents on the seafloor. “Seawater is layered similarly to a colorful cocktail. I am interested in the mixing between the individual layers within the ocean”, Andreas explains.

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He measures helium distribution to distinguish mixing processes between different water layers. There are two forms of helium: a light isotope and a heavy isotope. The heavy isotope is more abundant in the atmosphere, whereas the light isotope is released from the Earth’s interior and introduced into seawater by hydrothermal activity. Andreas uses helium isotopes to study mixing processes between water layers and the atmosphere.

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“Helium is a useful tool to identify up-flowing water masses which are rich in nutrients, such as iron.” Iron plays a key role in the ocean, as it is often a limiting factor for algal growth.

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Stefan Sopke has been working as technician in the Department of Geosciences of the University of Bremen fro 23 years. In the Petrology of the Ocean Crust research group, he is in charge of the electron microprobe, with which one can analyze mineral compositions: „The first step is the making of a polished rock slide, only 30 microns thick. The electron microprobe measures the concentrations of elements in these slides.“, explains the certified technician. The electron microprobe will tell you, for example, if the smoker sample we took yesterday contains Cu-bearing minerals“ reports Sopke, and point to a sample that lies on the table in front of him. With this method, I can not only tell you how much of an element is present in a sample, but can also produce images of element distriution as well as secondary electron and backscatter electron images, like in an secondary electron microscope.“ Besides this assignment, he also supports and consults the scientists in designing and conducting laboratory experiments.

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During the expedition, he measures the contents of hydrogena nd methane dissolved in the water samples brought onboard. For all the samples that come up every day with the ROV, we need eight hours before all the measurements are completed.“ Says Sopke. His working hours are between 8 p.m. and 3 a.m. During the day, he evaluates the results of the measurments and prepares and calibrates the gas chromatograph for the next round of measurements.   

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Prior to the expedition, I was in charge of ordering and securing all the materials and material safety sheets as well as the shipping logistics for our working group. In the month before the containers were shipped, I had little time for anything else.“, he says with a smirk on his face. „One often breaks a sweat, then, when you are told by the suppliers that they’ll be late with a shipment, because the day the container leaves the campus is firmly set.“, Stephan Sopke continues.  

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Corinna Oster is a Masters student at the Institute for Chemistry and Biology of the Marine Environment in Oldenburg. She is participating in the expedition as part of her studiesin marine environmental science and can even get credits for it. In the coming semester, she will use the data from the seawater and fluid samples from the expedition for writing her thesis. The topic of her thesis will be how the composition of dissolved organic matter (DOM) changes in the hydrothermal plumes. “Dissolved organic matter is molecules in the sea which can be used as nutrients by bacteria,” explains Corinna. She takes her samples from the CTD and the ROV MARUM QUEST. For her research it is important that the samples are taken from the plume of the hydrothermal vents. Furthermore, it is important that there is no contamination of the samples with organic matter. All plastic bottles in which the samples are stored for return to Oldenburg have to be cleaned carefully before using them. Glass containers are heated to 400°C to clean them of organic matter. Back in Oldenburg, she will determine the composition of the organic matter with a mass spectrometer.  

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Malin Tietjen is a PhD Student in the Department of Symbiosis at the Max Planck Institute for Marine Microbiology in Bremen, Germany. Her main focus lies in the symbiosis between the deep-sea mussels of the Bathymodiolinae group that occur at hydrothermal vents and their chemosynthetic bacterial partners. These symbionts live in the gills of the mussels and can produce nutrients for their host by using the chemical energy from hydrogen, sulfur and methane in the surrounding seawater. In return, the symbionts benefit from the constant flux of energy-rich seawater passing through the mussel gills. “We suspect that the symbionts also take advantage of the shelter provided by the host and thereby avoid being washed away by currents from the sulfur-rich seawater”, so Malin Tietjen.  

During the expedition, Malin Tietjen collects mussels with the unmanned submersible QUEST from the seafloor and later dissects the mussel gills in the lab to extract DNA and RNA. From the genetic information obtained, she can investigate which genes are responsible for the maintenance of the symbiosis, for example genes involved in the synthesis and exchange of metabolic products.  

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To become a marine biologist, Malin Tietjen left Germany where undergraduate degrees in Marine Biology are not offered, and moved to England to study this subjects fo her Bachelor’s and Master’s degree. “I always thought that the sea was incredibly interesting because it is infinite and full of life from tiny organisms to gigantic animals, all of which is poorly understood. I am fascinated by our oceans just like other people are fascinated by space because it has no end”.

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In 2014, German marine science entered on a new era with its new research vessel SONNE. With a length of 116 meters and a beam of 21 meters, SONNE not only significantly exceeds the size of her predecessor, she also sets new technological standards. Thanks to innovative marine technology and improved methods, SONNE´s scientists gain access to previously uncharted ocean depths. Some of the vessel’s equipment includes state-of-the-art echo sounders and winches with cables up to twelve kilometers long, making measurements even in the deepest oceanic trenches possible. Several underwater robots can be used simultaneously to image the seafloor and to bring valuable samples back on deck. These samples can be analyzed directly on board in SONNE´s 17 laboratories.

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The German Federal Ministry of Education and Research offers a range of publications on various topics as RV SONNE and marine science. You may also order publications free of charge.

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