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The ocean is not a quiet place. In fact, it is full of sounds originating from numerous different sources. Screening over a wide spectrum of frequencies, some of them are inaudible to the human ear.
Rain, wind, and waves constitute the main part of the background vocals in the deep eerie ocean choir.
Earthquakes, plate tectonics, moving glaciers, submarine landslides, and underwater volcanic eruptions form a constant bassline, whereas medium and high-pitched regional sounds of biodiversity produced by the staggering variations of animal communication sing the beautiful underwater melodies.
Some regions in the ocean are louder than others. The abyssal plain, not only said to be the ocean’s desert because of its flat vastness, but also because it can be sparsely inhabited, is hence rather quiet. Every now and then, it is being visited by migrating species, like whales, dolphins or turtles, who temporarily ensonify this otherwise so silent place.
This sound level however drastically increases when approaching a populated seamount. Usually, a high number of the most diverse creatures are romping about, producing an exceptionally vivid and unique sound scenery that stretches over an impressive range of frequencies and amplitudes. Snapping crustaceans really can be the loudest of them all – in fact, they are so loud, that navy submarines use shrimp clouds to acoustically hide in. But also chattering fishes or foraging dolphins, who use clicks to echolocate their prey, are remarkable contributors to this natural ocean soundscape.
Travelling at a speed of 1500 meters per second, sound in water is almost four times faster than in air. It can therefore cover enormous distances. Depending on physical properties like temperature and pressure, especially low frequencies can last for several thousands of kilometres. Indeed, there is a particular layer at 800 – 1000m depth where sound speed is at its minimum, allowing low frequencies to circle almost entirely around the globe. It is known as the SOFAR (Sonar Fixing And Ranging) channel and migrating animals such as whales use it for long range communication with other far-away mates. But they are not the only ones: navy submarines benefit from this way of audio connection to send information around the world within seconds. This triggers a conflict of interest, causing whales to become distracted and straying off, commonly ending up with them beaching in shallow water regions.
But even outside the SOFAR channel, the deep rumble of a feeding fin whale can be heard over 15km away from its position (Watkins 1981). They use a variety of sounds to communicate, some of which are solely used to target food when hunting, others to navigate during their long transits to different places. But the long and low-pitched humming in particular remains an unresolved mystery. Some say whales sing for aesthetics or artistic reasons. A beautiful idea and a very equitable one, too – why should humans be the only species making noise for pure joy?
Of course, anthropogenic noise like ship traffic, drilling offshore installations, or military activities increasingly become the lead voice. We significantly increase the overall volume, not only of the ambient noise, but throughout the entire soundscape spectrum. In fact, the anthropogenic component of the ocean’s ambient noise has doubled in the last 50 years. It is an open secret that natural ocean inhabitants are at the very least distracted by this constant noise shower. Likewise, the fact that animals show different behaviour as a consequence of permanent sonication has meanwhile reached common knowledge as well as the rising number of serious hearing damages or cases of death and beaching due to noise.
Recent studies have revealed that blue whales respond to anthropogenic noise overlapping with their vocalisation (Melcón et al. 2012). When hunting, blue whales amplify and stretch their foraging calls (‘D-calls’, usually less than 100Hz) in the vicinity of mid-frequency sonar and ship sounds. It was also observed that they entirely cease to sing when distracted by ambient, non -‘natural’ sound, such as ship traffic.
The good news is that, in contrast to other pollutants, like chemicals or plastics, noise can be switched off. If we put efforts in reducing the man-made share of sounds in water, we could actually get rid of it. And efforts are being made to reduce submarine noise pollution and monitor sound in the oceans. For instance, permanently installed hydrophones in high-traffic areas or on deep-sea moorings help to understand and observe ocean sounds over the long term. Thus, recent studies have revealed that during the Covid pandemic, the noise level of major shipping routes significantly dropped (e.g. De Clippele & Denise 2021). New developments within engineering technology and smarter engine construction allow for reduction of ship noise.
As this blog is not for once about the visual beauty of the deep sea, there won’t be any pictures this time. But why not instead take a sonic tour about the ocean’s vast soundscape? (Use headphones!)
The Humpback Whale: https://freesound.org/people/MBARI_MARS/sounds/403406/
The Killer Whale: https://freesound.org/people/MBARI_MARS/sounds/458854/
The Fin Whale: https://freesound.org/people/MBARI_MARS/sounds/403841/
Rain at 900m water depth: https://freesound.org/people/MBARI_MARS/sounds/404317/
Live from Monterey bay – Eavesdrop on the deep sea off California: https://www.mbari.org/soundscape-listening-room/
The French band “Doucha – music of the depths” translated deep sounds recorded by hydrophones into lyrics. Lead voice is the captain of the French research vessel RV Pourqoi Pas?: https://youtu.be/QuJ95bBJgIw
And here’s a snippet from our own hydrophone record – can you name it?
Melcón, M. L., Cummins, A. J., Kerosky, S. M., Roche, L. K., Wiggins, S. M., & Hildebrand, J. A. (2012). Blue whales respond to anthropogenic noise. PloS one, 7(2), e32681. https://doi.org/10.1371/journal.pone.0032681
Watkins, W.A. (1981): Activities and underwater sounds of fin whales. Sci. Rep. Whales Res. Inst., No. 33, I981, 83-117.
Rhachotropis, who? While this question may seem alien to most of us, it is commonplace to others. And to anticipate it: Rhachotropis is a genus of amphipod crustaceans (known as beach hoppers) that is widespread in the deep sea and one of the key players we encounter on this expedition. We, that is, the deep-sea taxonomists here on board, who, roughly speaking, deal with the identification and naming of species. And that can be damned difficult at times. Partly because specimens that we sample from the deep sea are too damaged to reliably name them. Partly because species can simply not be distinguished, since from the outside one species just looks like the other – although their DNA would tell you they are different (something that we call cryptic diversity). And above all, despite all the advances made after 150 years of deep-sea research, sampling the deep ocean floor remains a major challenge. And the forces of nature that we experienced during this trip made this more than clear to us: deep-sea research involves great effort and commitment, is logistically complex and only possible if everyone on board, crew and scientists, pull together.
Hence, naturally, deep-sea taxonomic work is a lengthy one, starting with sample collection, sieving, sorting (i.e. hand-picking individuals from the mud), photographing and initial rough identification, which, including genetic analysis, can already be achieved on board. However, the mammoth task follows in the home laboratory. Here species are further identified and, if recognized as new, named and described. How long this process may take cannot be quantified across the board, but several months to years are not uncommon. To speak figuratively, as a taxonomist you need a lot of stamina, i.e. being more of a long-distance runner than a sprinter. At the same time, however, taxonomy research is more sustainable than any other: species names are still valid after hundreds of years, and specimens from these historical descriptions are available in natural history collections.
But still, can’t the whole thing be shortened and why is it even important to name species? Living in a time of considerable environmental change, which also extends into the depths of the oceans, we want to know what are consequences for the resident biota? And these can be very different, depending on which species we are dealing with. Coming back to the Rhachotropis example, it makes a huge difference if we find Rhachotropis aculeata, a species common to the North Atlantic, or Rhachotropis boreopacifica usually found in the North Pacific, and thus likely to be an invasive species. Time is of the essence to identify all the different threats to the deep-sea fauna. Therefore, new methods in taxonomy are constantly being developed to accelerate taxonomic work, including modern imaging tools or molecular methods – just to mention metabarcoding or e-DNA, which are also being used here on board. Molecular methods can provide independent evidence of species identification and thus be a valuable addition to traditional morphology-based taxonomy.
According to current estimates, there are thousands upon thousands of species to be discovered in the deep sea, and it is clear that we can only preserve what we know. So, whatever species the next samples will bring to light, we name it!
Uh, what? Wait, in an earlier blog entry they covered dinosaurs, now they are talking sci-fi stuff… aren’t they supposed to explore the deep sea, with all its odd but beautiful creatures?!
Well… actually yes! But as the weather is still treating us roughly and the first station work is yet to be done, it might be about time to talk – yes indeed – about time travelling!
About 125 years ago the Danish “Ingolf” expedition started – a scientific cruise to explore the deep Arctic sea around Iceland and Greenland. Among meteorological observations, abiotic measurements, botanical work, and investigations regarding fishing, the cruise report of Captain C. F. Wandel mentions zoological work and sampling for collections as the main objective for the voyage. But that’s not the end of the similarities between their mission and ours. They started their journey from the Faroe Islands, travelled up northwards of Iceland, fought bad weather again and again, and finally sampled in the Davis Strait west of Cape Farewell, which we – surprise surprise – passed nearby. Furthermore, on board the Ingolf was a zoologist and taxonomist by the name of Dr. Hans Jacob Hansen, which Nature titled “one of the most distinguished of the long line of descriptive zoologists who have placed the Zoological Museum of Copenhagen in the very front rank of the museums of the world.” (Nature, 1.8.1936). His particular interest laid in the investigation of Crustaceans especially the order Isopoda. He described numerous new species discovered during the Ingolf expedition, including a species called Chelator insignis Hansen 1916, which was found east of Greenland in the Labrador Sea. More than a hundred years later, this species was found south of Iceland during the BIOICE project (Benthic Invertebrates of Icelandic waters) and the IceAGE project in huge numbers (>6000 individuals in only BIOICE!), by enthusiastic marine biologists Jörundur Svavarsson and Saskia Brix, who are – like Hansen in previous times – experts in isopod taxonomy. But how did the tiny isopod get there, what are the pathways that it used to travel such an enormous distance? Is it genetically related to the population in the Labrador Sea? These are just a few questions we want to shed light on within the IceDivA2 project.
So here we are steaming over the rough North Atlantic, passing a total of five time zones and over a century of marine research to the original area in the Davis Strait, following in the footsteps of H. J. Hansen and the Ingolf expedition. Continuing their fundamental work with the most modern techniques of biology, geography and hydrography – time travelling at its best!
Mentioned for the first time in the third millennium BC, and originally described as ‘shining lights’ or ‘large flashing arches’, northern lights are one of the most spectacular natural phenomena which can be observed on earth. Driven by charged particles emitted from the sun – the so-called solar wind – they can be seen in both the southern (aurora australis) and northern polar regions (aurora borealis), typically at latitudes of more than 60°. Their appearance is thereby restricted to the respective winter months (northern hemisphere: September to March), when the sky is dark enough during nighttime.
On its sun-shaded side, the Earth’s magnetic field has the shape of a long tail, reaching millions of light years behind. Once the solar wind spreads into space it develops its own magnetism, causing the earth’s magnetic field to deform. Charged particles travel along the tail verging towards the nocturnal side of the Earth where they enter the pre-atmospheric plasma sphere. The majority of the particles are bent towards the poles and ping pong back and forth between them – which in turn again increases the magnetic field strength, forming somewhat like a magnetic trap.
Especially in the polar regions, some of the charged particles are fast enough to enter the atmosphere. They collide with molecules such as oxygen, nitrogen, and hydrogen. The collision kicks out electrons sitting in the outer atom’s shell from their initial place. This process causes energy to be released in the form of light – the aurora! Quite often, free electrons can cause even further stimulations of molecules, hence light emissions, in the atmosphere.
Northern lights appear in several different types of colours and shapes. Ranging from stable arcs winding in east-west direction to curved bands or even spirals. Their shape mainly depends on the Earth’s magnetic field and the resulting movement of the charged particles. The colours of the aurora as we observe them are determined by the atmospheric compounds and the amount of energy they emit: Green light, for instance, is radiated by free oxygen atoms, while nitrogen ions typically release blue and purple rays.
Given the fact that we are weathering several storms in the shelter of the Faroes, I would like to tell the story of how this little island chain evolved.
When dinosaurs left the planet 60 million years ago, a plateau on the Scotland-Greenland ridge was born. Numerous lava flows from volcanic outbreaks, caused by the divergence of the American and the European continental plates, have created massive solid basalt deposits of up to 30m thickness. Each of those layers bears witness to an eruption, individually separated by thin sheets of tuff – a remainder of the ash rain that is blown out after an outburst.
When the volcanic activity ceased, rainwater rivers started to make their way through and into the rocks, leaving behind sharp ravines and deep dykes which meander all across the plateau – a process, that’s been lasting for centuries. It eventually led to the slow top-down division of the plateau into separate fragments.
Glaciers then took care of the rest and gave the islands their structure as we know it today. Massive ice bodies glided along the ravines and through the canyons. Moraines and pebbles trapped in the ice have ground down the subsoil to an even and plain surface, eventually shaping the characteristic trough valleys.
However, not only fresh water and ice shaped what we today experience as a picturesque island chain – also the powerful North Atlantic water masses – which we became acquainted with very closely in the last couple of days – have not exactly been lazy in the past: High waves and strong winds constantly eroded and washed out the lighter sediment sheets, causing a vast part of the plateau to collapse – and only the Faroes, Iceland, and the Hebrides survived.
Due to their young age (yes, 60 million years is just a flick of the eyelid in our planet’s past!), erosion on the Faroes is not yet far advanced. It is for this reason that the bluff outlines are so typical and unique, having evolved giant, extremely sharp edged and almost perfect vertical walls over time. Depending on literature, Faroes’ cliffs count towards the highest of the world.
Erosion is not only the cause for the size of the walls, it is also the reason why there lives such an exceptional biodiversity. A vast number of bird species built their nests into the tiny holes of the steep walls. They form when, over time, water and fierce winds wash away unstable parts of the cliff. The winter storms can be so strong, that the spray of the waves reaches up to 50m.
All images below by Mia Schumacher, GEOMAR.
Welcome to our cruise blog! Lovely to see you (back) here.
After setting sail yesterday morning, 5 November, we are already heading through rough North Sea weather. I mean, who would have expected something else than stormy and choppy waters at this time of the year in that location? Although, it is still relatively calm compared to what weather we expect to come within the next couple of days… A little spoiler here: Our original plans are blown with the wind for the time being – and are replaced with weathering the storm by hiding in the wind shelter behind the Faroe Islands.
Therefore, at this stage we do not have a lot of scientific stuff to talk about (yet). What we do talk about though is the UN Ocean Decade – a massive ambitious initiative designed over a ten-year timeframe and dedicated to our ocean. The aim is to wrap up all the different social, economic, industrial, political, and scientific interests concerning their – partly very divergent – demands on the ocean and bring all those parties together on one table. The overarching goal is a resilient and healthy ocean by 2030 – and until then join forces to find ways and figure out how to reach this. This can be practical approaches e.g. ‘invent tools to stop plastic discharge from estuaries into the oceans’ or more general foci on communication strategies about how to bring people together to talk. We are very proud that our IceDivA2 cruise is part of the UN Ocean Decade programme in the frame of a satellite event – a two-hour time slot showcasing our on board activities for a clean ocean. Just as a heads up: We will be hosting a live stream which enables everyone interested to come aboard and unite from all over the world. So – save the date and join us live on the 18 November between 5 – 7 pm CET! More information and a link to the livestream will follow in a later blog entry.
In the meantime, we prepare – both for the upcoming weather and the livestream – all the gear, labs, and instruments we brought with us. Amongst these is benthic gear such as the epibenthic sledge, multi – and box corers, and also water column sampling instruments such as plankton nets and water sampling devices. To dive down into the world of the ocean floor, we use ship-borne multibeam echo sounding as well as our deep-sea towed camera system which provides us with beautiful footage. Let’s see what the future brings! Stay tuned to keep up with our journey into the North Atlantic!
As I began my master’s in biological oceanography in Kiel one year ago during the pandemic, I could not do as much field work and lab work as planned. The last year was tough due to all the online courses, which is why I am excited to join the current research cruise on RV SONNE and again gain practical experience in marine sciences. Two years ago, I was an intern at GEOMAR in Kiel and remember when my supervisor showed me the 360° online tour of Research Vessel SONNE. We were so impressed by this state-of-the-art, highly technological deep-sea research vessel and I would’ve never thought to be once part of the scientific crew on board. Well, here we are. Emden, 05.11.2021, 8.00 am – my first cruise on RV SONNE begins.
Two days ago, all scientists needed to do a corona test and luckily, all of us were tested negative and could join the cruise. We are an international team of 27 scientists from the Senckenberg Institute in Wilhelmshaven and Hamburg, the GEOMAR Helmholtz Centre in Kiel, the British Antarctic Survey in the United Kingdom, and the Universities of Hamburg and Oldenburg. Although several different projects and working groups are incorporated on board, all scientists together with the crew function as a single team. For me, it almost feels like a small family you’re travelling and working with for the upcoming weeks.
Our expedition, IceDivA2, will take us from Emden (Germany) towards Norway, and from there, off the coast of Greenland; assessing the genetics, ecology, and biodiversity of marine animals. To reach the North Sea, we first had to pass through the lock in Emden. Once again, my greatest respect to the captain and the pilot who impressively navigated this huge ship through the small opening. It was lovely to see for me that my family came all the way to Emden to watch the departure and say goodbye. That way, we also got some nice pictures of the vessel leaving Emden. With this lovely support in mind, I will now begin my adventurous journey through the stormy North Sea into the Atlantic Ocean to investigate the so far poorly explored biodiversity of the deep sea.
The iMirabilis2 team
The iMirabilis2 expedition has always had capacity building and outreach at the centre of its goals. This blog and website are two of the outputs created to help share the science we conduct at sea. Throughout the cruise we also ran a smaller, personalised programme called the ‘ship-to-shore buddies scheme.’ Through this program, iAtlantic fellows and other associated early career researchers were given an insider’s look at life on a cruise. This group of 18 onshore buddies were paired with the early career researchers on board to stay up to date on the happenings on the Sarmiento de Gamboa. Onshore and offshore buddies created a WhatsApp group to share daily updates and communicate informally during the cruise. There were also weekly zoom calls on Thursdays (see photo, right) for the buddies to get live access on board for one hour. Each week a training video would be shown on the call and any questions were answered. A piece of kit or a research technique was then explained in detail after which a discussion occurred. The on shore buddies got to connect with myself each week along with appearances from Bea Vinha, Daniëlle de Jonge, Alycia Smith, Richard Austin-Berry, and Eoin O’Hobáin.
Everyone on board had a great time connecting with the onshore buddies. It was exciting to share updates to the group and be met with enthusiastic responses. The zoom talks were engaging and some questions meant I spent 30 minutes finding out an answer for a buddy the next day. We wanted to focus on some of the on shore buddies who joined the scheme in this blog post by having them share a bit about themselves and how they found their experience in the scheme.
I am a Colombian deep-sea lover with a great interest in the taxonomy and ecology of deep-sea benthos. I worked on deep-sea brittle star systematics during my Masters at UNAM, México, and on taxonomy and ecology of deep-sea and sandy beach macrofauna from the Caribbean Sea at the INVEMAR institute in Colombia. During my PhD at the Universidade Federal do Espírito Santo (UFES) in Vitória, Brazil, and as an iAtlantic fellow on WP4, I am studying how climate change is impacting deep-sea benthic ecosystems, identifying and quantifying the effects of these changes on benthic ecological processes.
Unfortunately, I was not able to participate in the iMirabilis2 expedition due to the COVID-19 pandemic, but I am part of an excellent team that made it possible all our experiments in Cabo Verde! Daniëlle and Alycia did an excellent job testing how the temperature increase and the decline of organic matter quality to the seafloor can affect the benthic deep-sea life for next century. They really made me feel part of the expedition, keeping in touch with me, and sharing everything that happened with our onboard work. In addition to Kelsey who shared with us all their adventures in the middle of the ocean every day! iMirabilis2 was a great expedition! I am excited waiting for my samples, to identify them and analyse them isotopically to see our final results, and to compare them with those of our iAtlantic future expedition in the Santos Basin, Brazil (study area 10) next year!
I am Dkawlma Tora from Togo and I live in Cape Verde for my studies. I am a Master student at Technical Atlantic University of Mindelo- Sao Vicente through WASCAL Scholarship. The area of my study is Climate Change and Marine Sciences.
I am very excited about the marine domain (marine pollution) and iMirabilis2 was of great interest to me because the Shipboard training is part of my upcoming courses. It was very awesome to follow their work day by day on WhatsApp and to meet the staff and speak with them by Zoom calls. It enabled me to know more about the implementation of research with vessels, the equipment and its use. It was also amazing to discover the riches of Cape Verde Sea’s life.
I am an instrument technician at the South African Environmental Observation Networks Offshore node based in Cape Town South Africa. Here, my main duties are the planning and execution of at-sea surveys and the operation and maintenance of the sampling equipment used during those surveys. The sampling equipment I operate relies on underwater visual and physical sampling equipment to investigate long-term ecological change in the understudied deeper waters of South Africa. Although my scientific interests are broad, understanding and quantifying the habitats of benthic fish and invertebrates inhabiting South Africa’s offshore ecosystems is my primary focus.
The ship-to-shore buddy experience was amazing and the fellows definitely made us feel like we were part of the scientific team. Our Thursday evening chats were definitely something to look forward to, and I enjoyed every aspect of it! I especially enjoyed the benthic landers and camera trap discussion sessions and I was really fascinated by the interesting fish fauna that were sampled. Even though I was supposed to be a participant on the cruise, the ship-to-shore buddy initiative made the missed opportunity feel less like a loss. I would like to commend the fellows for their efforts!
I am a Masters student in the Biological Sciences department at the University of Cape Town using a remotely operated vehicle to explore temperate mesophotic ecosystems on the Wild Coast of South Africa.
Research groups all over the world should run a ship to shore buddy program on all research expeditions big or small. This platform has created a space for relaxed interactions between emerging scientists from various parts of the world to exchange ideas and learn new skills. The weekly zoom calls were immensely interesting and have given me insights into the challenges and opportunities of multidisciplinary deep sea research using state of the art technologies. I hope to be part of many more programmes like this one.
I am Mauricio. I live in Brazil, where I graduated in Oceanography in 2019 at the Federal University of Bahia. During my undergraduate program, I focused on understanding the carbon cycle in the blue carbon ecosystems and how anthropogenic impacts may alter its ability to store carbon. Nowadays, I am a master’s student at the Federal University of Rio Grande, where I am working with polar biogeochemistry (carbonate system parameters in the Northern Antarctic Peninsula). Also, I am one of five students awarded with the West P&I Bursary 2021 at the National Oceanography Centre – University of Southampton. I love getting in touch with the marine environment and experience new moments with it, such as fieldwork in coastal zones and cruises in the open ocean.
The Whatsapp group was an excellent place to keep us updated about the activities on board at the iMirabilis cruise throughout August 2021. This group, along with the Zoom meetings weekly, was a good experience to participate in a cruise even we were not on it in person. The multidisciplinarity on the iMirabilis cruise was terrific. Indeed, the buddies on board translated that scientific environment through discussions, presenting some methods and previous results, and how to work with new approaches for me, personally, such as the ROV used. That time together was like a class to explore the potential of this cruise while it was going on. Even with some experience on board, the people’s disposition on board was essential to making this experience a great one. Every time we had a question, they spent efforts to get information from the other people on board to bring to us as much information as they can. In summary, this experience was like a logbook with constant updates that certainly added a lot to my career as an oceanographer.
My name is Pedro, I’m a biologist and I recently started my Master’s in Oceanography. I will work with the distribution and taxonomy of the octocoral genus Primnoella in the Campos and Santos Basins as a part of the iAtlantic Project here in Brazil.
I was very excited when Kelsey invited me to the Ship-to-Shore buddy program and also with the opportunity to get an inside view of an oceanographic expedition. It was great to learn about the routine in a scientific ship as well as the research other team members are doing, and how they come together to solve any problem that would come up. Overall, it was a highly enriching experience, especially getting to know other early-career scientists who share as much admiration for the deep sea as I do.
My name is Renata Arantes, I am currently a postdoctoral fellow in the iAtlantic project. I work with deep sea habitat characterization, focusing on deep-sea coral habitats in the Brazilian continental slope. My postdoc project deals with deep-sea octocoral alpha taxonomy (based in morphological characters) and the development of a set of macroscopic characteristics for the recognition of these species through ROV images, wherever it is possible.
It was a very interesting experience to be part of the ship to shore buddy program. I finally got to know some of my iAtlantic fellows and had the opportunity to communicate regularly with them during all cruise. iMirabilis was an international multidisciplinary expedition with so many different activities that even remotely allowed us to know in detail all the sampling methods as well the functioning of the sampling devices, which some of us never had the opportunity to work with before. Besides our weekly meetings we interacted by message very often getting first-hand the daily expedition’s highlights, which was pretty amazing when you realize that the Cabo Verde region was a unexplored area, a privilege for those who work in the deep sea.
My name is Daniel Quaye. I am from Ghana but currently in Cape Verde as a student in the WASCAL master’s research program in Climate Change and Marine Sciences at the Atlantic Technical University. I am interested in ecology and population dynamics, and how environmental changes impact aquatic populations.
As a young scientist looking forward to my first cruise next year (fingers crossed), I recognized this innovative ‘Ship-to-Shore’ buddy system of iMirabilis2 as a good training opportunity. Indeed, my virtual interaction with fellows on the expedition has been very beneficial. My learning experience ranged from discussions on life at sea (mostly devoid of sleep), clothing, popular medication, as well as a dive into the different research questions being pursued by fellows.
Over these past couple of weeks, I have been exposed to knowledge on deep-sea ecosystems, their functioning, sampling techniques and illustrations of various equipment and instruments (an ROV, AUV and benthic lander). The buddies WhatsApp group was mostly buzzing with regular updates. Despite their busy schedule, I found fellows ever ready to share and explain different aspects of their work to us. It was also quite satisfying fellows were able to share preliminary results from their analysis via our weekly live chat on Zoom.
Overall, though I followed the expedition from a desktop, I think it’s fair to say I was part of this novel exploration of the deep-sea ecosystems of Cabo Verde. The entire team’s level of engagement was high. A big appreciation to the all fellows (Bea, Kelsey, Danielle, Alycia), the organizers and members of the different research teams for such a wonderful experience.
Thursday afternoon, 26 August. I’m sitting in the acoustics lab, monitoring the multibeam echosounder. We are carrying out our last bathymetry data collection as we are leaving our study area. Data collection until the very last moment!
Finally I can find some peace and quiet to reflect on the past 4 weeks. It has been a whirlwind of an expedition, and only now I’ve found the time to read all the blog contributions (thank you Kelsey, Vikki and the whole outreach team for pulling this together!), and to gather my own thoughts.
As I said: it has been a very busy expedition. Our research had lots of facets, we used lots of different types of equipment, which all together led to lots of different operations at lots of different locations. This resulted in a complex and challenging planning exercise, which our chief scientist Cova carried out expertly!
All that planning and all these operations required a good spatial awareness and understanding of the study area. The question “where are we, and where will we do the next operation?” was always on my mind. To answer it, we used a Geographical Information System (GIS) populated with, among others, existing bathymetry data, but we also gathered our own. Based on a careful interpretation of these bathymetric maps, we planned the ROV and AUV missions, chose coordinates for coring, CTDs and lander deployments. Looking back at it, the only thing I can say is: we covered a lot of ground!
Between helping Cova with the planning, choosing coordinates and waypoints, and the coordination of operations during the night (a task shared with Andrea Gori), I also had the chance to take part in some of the science work, particularly the coring, multibeam mapping and the ROV dives.
Coring operations always provide excitement and anticipation. When the core lands on the seabed, after sometimes more than 2 hours of winching down (for cores at >4000m water depth), we watch the tension on the wire carefully. Did the core land properly? How much does the tension increase when we start winching the core back up? Does this suggest a good sediment recovery? Then we have to wait again for more than 2 hours until the core is on deck and we know the answers! Once a multicore arrives on board, the six core tubes are subsampled in different ways, to provide sample material for a variety of analyses and research questions. Generally this is a fun activity: as adults we get to play with mud without any questions asked! I’m sure Erik, Susan, Cova, Andrea, Kelsey and Bea would agree. When our interpretation of the bathymetry suggests that the sediment may be coarser (e.g. sand), we use a boxcore. On Cadamosto Seamount we tried several times to take boxcores, with varying success. It is not easy to find the pockets of sediment that can be cored on a seamount! Whichever were the outcomes of the cores, it was always a pleasure to work with coring techs Mario and Ivan. Lots of good conversations at 3am while watching the core go down or come up!
Also working with an ROV is always a treat: there is always some discovery, even if it’s the discovery that there isn’t much to discover… By itself that fact tells us something about the area, the seafloor habitat, the geological, biological and oceanographic processes going on. However, during this expedition we had a lot to discover, and the habitats on the flanks of Brava, Fogo and Cadamosto host the most amazing coral gardens and sponge fields. It was very nice to work with the Luso ROV team, they are very professional, 200% dedicated, and just super-friendly! Having the possibility to adapt the vehicle to accommodate the RoCSI sampler and an extra camera for the last 2 dives made our work with the Luso extra special.
Compared to the buzz of coring, lander recovery or ROV work, gathering bathymetry data with the ship’s multibeam echosounder feels like an operation at a totally different pace. It is fascinating to see all the details of the seafloor morphology being painted on the screen, ping by ping. To paraphrase a well-known advert: good things happen to those who wait! I’m very grateful to Pablo, our acoustics expert, and everybody who joined in with the task of monitoring the multibeam echosounder. The system mostly works independently, but occasionally it needs a nudge or a tweak, so we always had somebody on watch during dedicated operations.
Unfortunately our AUV Autosub6000 was plagued by several technical issues. This was extra frustrating for me because I have had the chance to work with the team and the vehicle several times before and I know what fantastic data they can provide. It would have been great to have high-resolution maps of Cadamosto, combined with eDNA samples and extensive photography. However, such is the nature of work at sea, particularly when using complex and advanced technology: the more complex the system, the more challenging to operate all components at an optimal level. The Autosub team, together with Susan, took on this challenge in full, and despite the setbacks we obtained the world’s first eDNA samples collected autonomously at >3000m water depth. That is quite a feat!
As I am writing these words, we have just gone past the last waypoint of our dedicated bathymetric survey. That means the core operations of the iMirabilis2 expedition have now finished. It feels a little surreal… The main thing I will take home from this expedition is the impressive collaborative spirit across the teams and the crew, and the resilience of everyone on board, constantly adapting plans and finding new solutions for problems and challenges. This too is the nature of work at sea: we’re literally ‘in the same boat’ and have to make things work with the means we have – and the whole team have done so brilliantly: scientists, technicians, and also the crew and officers, who have been working with great professionalism. A massive muchas gracias, obrigada, dankjewel, thank you very much, mille grazie to everyone on board!