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We have spent three spectacular days in a row in the deep! Today and yesterday, we dived down to the beginning of Aegir Ridge fracture zone with our ROV and witnessed, once again, the most stunning impressions of life on the unknown mysterious seafloor. Nothing can describe what we look at better than images and that’s why I will stop writing soon and let the photos speak! Just one more important thing to mention at this point: Yesterday (4.7.2020) was the 300th dive for the ROV Kiel 6000. This is a good opportunity to congratulate the excellent ROV team and thank them for making these unforgettable dives possible! It’s an honour to be part of this fantastic journey with such remarkable imagery of the flourishing life below the water surface.
Day 13: Friday 3 July 2020
A day full of mapping! We have put behind us 20 hours of transit to our next survey area, located just east off the Icelandic continental shelf, at the very beginning of Aegir Ridge. That’s where we expect to find reefs of cold water corals – the ‘Lophelia’. Corals are, as any other hard substrate on the seafloor, the solid base to most marine life. They build vast reef areas and are home to the most delicate biodiversity. Although being totally different in appearance and motion, medusae (or jellyfish) and corals have something in common: both animals belong to the group Cnidaria. They use nettles to capture their prey and to defend themselves against predators. However, unlike jellyfish, the corals’ harpoon-like nettles sit in cnidocytes and can be expelled whenever something is passing by.
Depending on the local water depth, corals can be seen in the multibeam bathymetry. Hence doing a careful map survey in advance to a ROV dive can save a lot of time as the location of the dive and where to take samples can be decided a lot more precisely. However, it’s also important to know the local water depth, which can usually be derived sufficiently enough from satellite altimetry (down to a resolution of about 1km, the seafloor topography can very roughly be obtained from satellite gravity measurement). In this special case however, at the beginning of Aegir Ridge, the difference in depth between the altimetry model and the true multibeam bathymetry was up to 1000m – and that makes a huge difference if the water depth is between 700 and 2600m!
Another day with a successful ROV dive finished. We observed various different species and traces – from the most peculiar feeding trails made by Holothurians (sea cucumbers), tracks from trawling nets, piled up sediment with a wormhole on top (which resembles a mini volcano), small red shrimps drifting slowly through the water, and lovely sponges in the middle of the deep-sea desert that are blooming with life and give home to a lot of small creatures. A lot of the species are known already and can be identified in real time by the deep-sea life experts on land who are watching the video stream and tune in on board via live chat.
All of a sudden during our journey along the seafloor, the environment has changed and we are facing a massive slope which is quite steep. This is probably the remnant of giant debris flows of former times and moving plates, when the Aegir Ridge was still tectonically active. A consolidated sulphite substrate bottom is home to various species of crustaceans, sponges and also polychaetes – little worms that live in/on the benthos. Surprisingly, not one single fish was around although this region is known to be a popular fishing area. Just before the ROV ascended back to the ship, we found a plastic tube sticking in the seafloor. It was already forming a home for an anemone and decapods – a literally living example of the fate of litter on the deep-sea floor. Once it sinks, it rapidly becomes a vivid habitat to all sorts of animals. However, it also starts to decay, falling apart into smaller and smaller pieces until it is broken down to sub-millimetre sized pieces. These are taken up by the tiniest animals in the food chain, those are eaten by the next bigger ones and so on and so forth, until it is everywhere, in every body. This is not only theory, let’s face it – our biologists on board have already found microplastic in the sediment from 3000m water depth when examining the MUC, EBS and box core samples. It is already all around us and it’s probably impossible to ever totally free our oceans from microplastic again, but we should strive to stop putting more in.
As expected (and also known to be typical in the North Atlantic), the bad weather hit us over the last two days. Although perhaps ‘bad’ is not a good word as rocking hard in big waves is some sort of a thrilling experience that some of us really enjoyed. Others had to struggle with serious sea sickness and breathed a sigh of relief when the sea calmed down again.
Working on the main deck was becoming more and more impossible, and when the wire of the MUC was becoming tricky to handle, chief scientist and captain decided to cancel all in situ operations (box corer, CTD, plankton net, EBS, MUC). The only activity that is usually feasible in such conditions is mapping the seafloor and that is what we tried to do, heading north against the wind and waves to stabilise our course. However, at around 2 a.m., the ship motion became so severe that even mapping was not possible. The bridge ordered to stop the survey and do ‘weathering’ instead: Trying to remain in place, keep the roll and pitch movement low and wait until the storm is over. Luckily, this happened to be right on the polar circle! So we got the opportunity to spend one night on the border to where the sun never sets in summer and never rises in winter time. Amazing! Although, very honestly, I couldn’t have told we’re on the polar circle- it didn’t look different, neither the water, nor the seafloor. Nevertheless, it is exciting to be up north at 66° 33’ N with daylight all around the clock!
When the wave height decreased in the next morning, we continued our daily business and started doing a CTD profile. One interesting fact about our study area in the Norwegian Basin is that two major water current systems join up here: the North Atlantic current carrying warm (well, 6°C) salty Gulf Stream water to the Barents Sea at depths around 50-100m, and the Norwegian Current, which transports colder (4°C) and fresher waters – mainly from the North and Baltic Seas – southwards. Although these differences in temperature and salinity may not seem big (both 6 and 4°C being very cold) they have significant effects on the water current system. Even those small variations result in density gradients which are, along with wind, one of the main drivers for keeping oceanic water masses flowing. This is essential for the transport and distribution of nutrients and hence the basis for all marine life. Furthermore, without functioning ocean currents, there would hardly be any existence possible as they act as our planet’s ‘air conditioning’. Thus, big waves are not only beautiful to look at – without them, we wouldn’t be here on this earth!
Back in Germany, summer time is reaching peak temperatures of at least 30° (even in Kiel!), but here we stay with a chilly 9°C and wind gusts of around 7-8bft. The dream of sunbathing on the deck soon dissolved into nothing when we arrived at 65°N. As waves are getting higher, moving around on the ship is becoming cumbersome and we expect the sea to become even heavier in the next couple of days…thus people may wonder why we are doing this, missing out on beautiful summer time and going in the cold north instead to see only water for five weeks and struggle with sea sickness? I can tell you – it’s so worth it. It is an experience that not many people will ever get the chance to experience: seeing what is there in 3000 m deep in the ocean on the video screen during the ROV dives, touching the seafloor sediment that’s being collected with the MUC or box corer, exploring the sea floor morphology and discovering new structures, bearing witness to the most peculiar deep-sea fauna, hearing the waves smash against the portholes in the cabins … or just sitting in front of the windows trying to spot some whales. And all of this is happening in endless daylight (because the sun doesn’t want to set in these latitudes in this season). It’s an experience nobody will ever forget.
And speaking of seafloor bathymetry, over the last few days we’ve been mapping Aegir Ridge – a former mid-ocean ridge that was active during early Eocene (about 50 million years ago). The associated seafloor spreading processes were one of the main drivers for the formation of the Norwegian Basin. The extinction of Aegir ridge is placed around 25 million years ago in the late Oligocene, meaning that there is no active tectonic movement now, but the typical ridge structures can still be observed in the hydroacoustic data.
Furthermore, unusual seafloor structures hold unusual species and this is what our biology team on board is discovering! What looks like mud-slinging and sludge silt digging is in fact the extraction of the most valuable ground truth data. From very old ancient sediment, conclusions can be drawn about the development of deep-sea life from ancient past right up to the modern day. It is a lot of work though and getting the mud on board is only the very first step: that’s followed by sieving and washing to get rid of the coarser particles, centrifuging to separate organic from inorganic matter, and then manually picking out the interesting bits to look at through the microscope. The ‘rough’ cleaning procedures are already done on the ship but the time intensive precision work is done back home.
Tina Stein (right) is a technical assistant at Senckenberg am Meer in Wilhelmshaven with a focus on biology and genetics. During the cruise she takes care of the plankton net and its catch. When deploying the plankton net, she is the responsible person for the work on deck. It has been her wish to go on a research vessel ever since she started her apprenticeship and now she is here!
A really successful ROV day with most beautiful imagery from the deep-sea floor, as well as samples that will help understanding the biodiversity across the north Atlantic abyssal plain, came to an end last night.
It was followed by a busy night deploying “Ursula”, the newly christened EBS (Epi-Benthos-Sledge), which is dragged over the seafloor to collect the upper sediment layer. Then came the box corer, which has a big shovel that digs into one spot of the seafloor rather than shaving off a large area. The final instrument of the coring class is the MUC, multicorer, that pushes cylindrical shaped tubes of about 10cm in diameter and 50cm in length into the seafloor. This is a good opportunity to introduce some more of our scientists to you – namely those who are in charge of these devices!
Stefanie Kaiser is looking after Ursula, the EBS. She is from Łódź University in Poland and, despite being German, representing a whole foreign research team who couldn’t join the cruise themselves because of Coronavirus travel restrictions. She enjoys working with isopods, not only because they are fundamental food chain fellows, but also because they are ancient creatures and therefore suitable for long term studies as they can tell stories from the far past but also from recent changes. To understand biodiversity and its transformation in a changing climate, isopods and amphipods are essential indicator species.
Anne Nina Loerz (CeNak, University of Hamburg) loves amphipods. Wherever she is, these small little crustaceans show up. Anne has been studying them for ages and, similar to isopods, they form the basis of the food web. They are key players in all marine environments down to the deepest trenches- and certainly in habitats where we will take samples during IceAGE3. Moreover, they also act as abyssal police(speci)men and deep-sea garbage collectors, i.e. cleaning up carcasses of other dead marine inhabitants. Anne promised to discover new species during this cruise, so stay tuned!
Nancy Mercado Salas from CeNak is taking care of the MUC (multicorer) and the meiofauna that is kept in its tubes after retrieval. She particularly likes ‘digging in the mud’ and the exciting fact is that at least 80% of the species are still unknown – meaning that in every MUC, there is something new to discover! In the remaining 20% that are known, Nancy’s favourite animals, the copepods (another type of little crustacean), make up one of the largest group of all meiofauna in the benthos. As with the other crustaceans, they serve to prove the theory on biodiversity transition that is connected to ocean acidification and a rise in temperature.
On the fifth day, we start the serious work. Around midnight, we (finally) leave the Norwegian EEZ and now we’re officially allowed to map! So obviously, we would be mapping all night long, sitting in the hydroacoustic lab watching beautiful subsea features and cleaning outliers while listening to the Rolling Stones. But, of course, not without having taken a CTD profile first – because that’s what you do when you arrive at a research station: measure the water parameters, which are the basis for any further operation.
The part that everyone has been waiting for since we left the harbour now arrives: The first launch of the ROV (Remotely Operating Vehicle) ‘Kiel 6000’. This vehicle is a 3.5-tonne heavyweight giant able to carry numerous different instruments, among which are cameras, traps, drawers to put samples in, spotlights (it’s pitch-dark at 3000m water depth!) and grasping arms, just to name a few. It’s controlled by two pilots sitting in a container on the deck of RV Sonne, guided by several different cameras on the ROV. One of the pilots, the leader of the ROV team on our cruise, is Fritz Abegg from GEOMAR – Helmholtz Institute for Ocean Research.
Since 2008, ‘Kiel 6000’ has been his baby and he has been flying it ever since. Together, they have had countless unforgettable moments. One such moment last year was finding (and retrieving!) a lander which has been lost since 2015 in the deep blue ocean! If Fritz is not working, he can be found on the aftdeck of R/V Sonne chatting with the other seven ROV crew members.
Steering an ROV is a highly delicate matter: it’s a balance between going as near as possible to underwater features such as corals, sea mounts or hydrothermal vents to get a close look or to take a sample, but at the same time be extremely cautious not to damage or destroy them. Manoeuvring along the seafloor by steering one or more of the 7 propeller screws is a challenge in almost complete darkness, especially when curious deep-sea inhabitants approach the ROV. I could write pages and books about the working principle and all the features of Kiel 6000 but I’ll stop here for now. The interested reader might find this paper interesting: F. Abegg and P. Linke (2017).
The best thing ever is that we have a livestream on YouTube for the ROV dives! Bear witness to true deep-sea life and journey down to the deep with us in real time:
Day four started with good news: We are going faster than expected due to the waves coming from astern and pushing us north! This means that we will reach our first station earlier than expected at midnight. So the serious work on deck will start soon.
The very first task will be launching a CTD to measure salinity and temperature at different depths, as well as to derive a sound velocity profile (SVP) for the whole water column – knowing the exact sound speed is important for the subsequent multibeam survey to correct the acoustic signals for their attenuation on their way down to the sea floor. If everything is in time, the multibeam survey will start around 1 am and should be finished by around 8 am, as this is the time when the plankton net will be deployed to catch those incredibly small but absolutely fundamental creatures.
After a hopefully successful retrieval of the net, we will unleash the technical marvel – ROV Kiel 6000 for the first time! That is, if the weather is kind…right now, it looks like if that could be a limiting factor…
Our first day of transit is quite busy with planning meetings, clearing-ups of already emerging jumble, and doing a safety drill to practice the worst-case scenario. As of yet there is not that much science going so I will take the opportunity to introduce some of our research group leaders!
Saskia Brix is our chief scientist and she works as a biologist at Senckenberg am Meer in Wilhelmshaven, Germany. She’s got the hat on for our cruise. Everything related to station planning, organising and decision making goes through her. She’s been planning this cruise since 2013 (at that time, the new R/V Sonne wasn’t even existing!), and it has been her heartfelt wish for it to happen ever since. Originally, the cruise should have taken place 3 years ago but it has been delayed several times. Then along came Coronavirus… but finally we’re all here now thanks to Saskia’s tireless and insistent efforts! Among marine animals, seahorses are her favourite animals, but she works with a completely different group: deep-sea crustaceans. Although the adventures with ROV Kiel 6000 were her dream for this expedition, in general her favourite device is the brand-new epibenthos sledge (EBS) called ‘Ursula’ that was ceremonially baptised yesterday. With this, she can devote to her most beloved field of research, the isopods (small crustaceans). Saskia has over 10 years’ experience in leading and participating in cruises, and she can tell many stories about life at sea. Here is one of them: It was on a cruise to the Neumayer station in the Antarctic, during a cold and ice-heavy antarctic summer, when they met a freighter that was stuck in the ice. It had to be freed from the ice, and soon it was discovered that the freighter had been running out of fresh water for days. So its entire crew ended up entering RV Polarstern to take their long overdue showers…
James Taylor is the group leader of the scientific ROV team. He is working as a biologist at Senckenberg am Meer in Wilhelmshaven and polar bears are his favourite animals. When he’s not at work, you can find him on one of the upper decks, nose in the wind. His major focus during the ROV operations on board is the video footage, offering the opportunity to see – in real time – what is happening on the seafloor and being able to get highly specific ground-truth data using non-invasive methods that do not harm deep-sea life. One of the most exciting adventures in James’ career was when he was invited to Cambridge to catalogue and reclassify samples of barnacles that were actually been collected by Charles Darwin himself! Apparently, Darwin had really bad handwriting!
Morgane Le Saout (GEOMAR-Helmholtz Institute for Ocean Research) leads the hydroacoustic group and organises the multibeam surveys in order to get high resolution maps of the seafloor. Knowing the topography of the ocean’s bottom in detail is the basis for any successful operations as a lot of information can be derived from bathymetry, such as sediment characteristics, slopes, under water features and many more. Morgane’s craziest experience related to science was a shark attack during a magnetometer dive – it probably considered the magnetometer to be something to eat because next to the bite marks, Morgane found a shark tooth sticking out of the plastic case!
Things are starting to become serious on the second day. It’s time to hit the road…uhhh no – to set sail and head off for Iceland! After settling and unpacking each single box containing lab equipment such as chemicals, microscopes, small bottles, large bottles, medium bottles, tools and a lot more, R/V Sonne is released from the ropes that are tying her to the pier. Hooting solemnly to say good-bye to R/V Maria S. Merian (one of the other German research vessels), who is lying alongside to us, R/V Sonne starts her engines to cast off. But before going anywhere we need to pass the lock that keeps the (very) low tide on the mudflats out of the harbour area and ensures the under-keel clearance. I can tell you, it is quite fascinating to see such a large vessel entering such a small gap and still being overtaken by other ships – the captain certainly knows what he is doing.
We leave the lock safely and now the open ocean is waiting for us. Our journey continues and passing huge wind parks, we go north, north, north… On the way up we will cross the exclusive economic zones (EEZ) of three countries: the Netherlands, Denmark and Norway. EEZs are those areas of the ocean that (except for some special cases) extend to 200 nm beyond the land-water-mark. According to the United Nations Convention on the Law of the Sea (UNCLOS), each country has sovereign rights in ‘their’ EEZ, meaning that no scientific operations (and no fishing, drilling etc.) is allowed to take place without permission. Thus, any research work and all its details have to be announced, depending on the country, up to 6 months in advance and approval has to be granted. Bearing this in mind and considering the Corona situation, it hasn’t been possible to apply on time for research permission in every country’s EEZ that is being passaged. Hence, there is some transit time which is very well used to get organised and plan the actions for station 1, located north-west of the Faeroe islands in the Norwegian basin. It’s just a tiny little bit south of the polar circle (65° N, 0° E)! But more on this tomorrow!