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In his video, from the first week, Dr Tim Le Bas discussed the proportion of the ocean that has been mapped. I quote: “15% of the seafloor is surveyed by the multibeam technology (size of Africa), but when we get to high-resolution, it is a tiny amount, like the size of Tasmania (0.05%)”.
Furthermore, the entire ocean floor has now been mapped to a maximum resolution of around 5 km, says Jon Copley in Just how little do we know about the ocean floor?. This map is realised from satellites observation (to know more, read this article: Gravity map uncovers sea-floor surprises). If we want to go at a higher resolution and study the seafloor in greater details, we have to use sonars and new technologies built on ships.
In 2016, I participated in a cruise (R/V Meteor 127) in the Atlantic Ocean where we achieved mapping at a different resolution. Every night, the ship was flying over the Mid-Atlantic Ridge to map the seafloor with a multibeam echosounder (at 30 metres resolution). In the daytime, the AUV Abyss (an autonomous underwater vehicle, from the German GEOMAR Research Centre) dived and mapped the study area at a resolution of less than 2 metres. This was outstanding, we saw so many details!
The advantage of an AUV is its autonomy. In few words, we launch it into the water and we bring back on deck 12 hours later. During this time, our research team works on other aspects of the mission (for example, sediment, rock or seawater sampling).
The same AUV has also realised two maps at a very high-resolution (50 cm!) at two different zones of hydrothermal activity. We could even see former vent chimneys! However, this mapping is time-consuming. In order to obtain high-quality data in a location where the bathymetry is highly variable (such as a mid-oceanic ridge), the AUV has to fly over the study area several times at different altitude. Afterwards, our team of excellent geophysicists will compile the data of the different dives to produce a finale high-resolution map.
If you would like to hear more about these missions, read these blog posts:
Now 4 years after Tim and Jon’s videos, surely we have increased the proportion of mapped seafloor. GEBCO is the General Bathymetric Chart of the Ocean. They have several maps free to explore online, and these maps show the names of the main oceanic features GEBCO World Map. Personally, I love it! Today, GEBCO, together with the Nippon Foundation, have a collaborative initiative called “Seabed 2030” with the aim of facilitating the complete mapping of the ocean floor by the year 2030. I am looking forward to taking part in the initiative in my next cruises.
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]]>My name is Adeline and I’m a third-year PhD Student (already!) at the NOC. I have been a MOOC facilitator for over a year now, and I’m learning lots of weird and wonderful things thanks to all your very thoughtful questions. If you’re curious about what I am doing (four words: Hydrothermal vents and mineral resources).
I invite you to read my three other articles about me and about my work
How did I become involved in marine science
What do the Oceans mean to me?
On board the James Cook, heading to some black smokers in the middle of the Atlantic
I was away for the 1st week of the course and unfortunately haven’t had the opportunity to meet all of you yet. My absence was due to holidays in Guadeloupe (Lesser Antilles Islands) to dive in the beautiful coral reefs there … To make amend of my absence, I would like to write about a very recent subject: Hurricanes Maria and Irma and their impact on the coral reefs.
The end of summer signals the peak of hurricane season (Aug-Sept) for those bordering the western side of the Atlantic Ocean. For those living in the Caribbean, this year’s storms where to be the worst since records began. Two category 5 hurricanes (Irma and Maria) followed each other and hit the Caribbean Islands. Irma was the first category 5 hurricane to ever strike the Leeward Islands at the end of August. Which left a devastating effect, the islands of Barbuda and Saint-Martin have been reported as having 95% of all properties destroyed. Maria, two weeks later turned from tropical storm to category 5 hurricane in less than 24 hours and struck the islands of Puerto Rico and Dominica mainly.
The diver guide I had in Guadeloupe told me stories about when Maria passed over the island. Fortunately the eye of the storm was further out to sea and the damages were lower than predicted. What a relief when I read the updates that the diving sites, mostly corals reefs on the West coast of the Basse-Terre territory (west side of the island) hadn’t been damaged. However the impact of the hurricane could be seen, there was a slightly higher than normal amount of rubbish on the beach, it’s not unusual to find large items of pollution in this area – bikes and large metal sheets often get washed up! The biggest visible impact on the beach was the beach itself, it had gone from being a sandy beach right down to the shore, which continued to a couple of meters water depth. It was now a beach which was rimed with large rocks and pebbles. Which had been deposited on the beach by a powerful wave action. We also noticed more plant debris in the water. There were a lot of boats which had been washed up on the shore, when the boats are loose they pose a lot of danger. If they collide with the reef, the reefs will be damaged and if the boats are damaged the fuel may leak. Which will have a serious impact on the water quality.
Now that I have seen the damaged caused by hurricanes with my own eyes, I wanted to search more about the real impact of hurricanes on coral reefs.
Hurricanes churn the water so much that the ferocity of the wave action can break the corals apart. The coral branches get snapped off and colonies are overturned. Imagine the reef suddenly being subjected to a washing machine cycle with great bit boulders and tree trunks swirling around. The biggest threat is that you get huge amount of pollutants and nutrients dumped onto the reef that upset the delicate balance between the corals (polyps) and the symbiotic algae living in them. Another aspect is the input of sediments over the coral reef. A thin layer depositing on the reef decreasing the precious visibility, i.e. the amount of sunlight penetrating the water column that the algae need for sustenance and growth. Therefore in both situations the algae leave the corals, and without the symbiosis, the polyps die and bleach.
But sometimes though, the influence can be also beneficial. This season, the surface temperature was higher than the rest of the year and the corals were under a thermal stress. To alleviate this stress, cyclones and hurricanes reduce the temperature by the transfer of latent heat, and inducing local deep (colder) water upwelling and shading at the ocean surface with primary productivity. It also scours dead organisms from the reef and enhances the bio-diversity by stimulating new colonies.
In the Caribbean, many dive centres and scientists have come to the same conclusions for this year’s season of hurricanes. They were expecting to see more damage, but in fact most of the reefs look spectacular again and although they did accumulate little garbage, thousands of passionate divers helped to clean it up. However, it seems that reef’s storm buffer capability (for the shorelines) have weakened in the recent years. This weakness comes from the increase of bleaching events and the warming waters. Resulting in a degraded coral reef with a relatively smooth surface, which reduces its natural protection against a strong storm surge. A healthy reef is more resilient and capable to recover after a hurricane.
Article based on four newspaper posts:
- https://www.washingtonpost.com/news/energy-environment/wp/2017/09/12/how-floridas-damaged-coral-reef-makes-it-more-vulnerable-to-storms-like-irma/?utm_term=.33bcebad44d2
- https://www.coris.noaa.gov/activities/caribbean_rpt/SCRBH2005_03.pdf
- https://www.livescience.com/60452-how-caribbean-will-recover-from-hurricane-irma.html
- https://www.sanpedrosun.com/old/99-343.html
Further reading
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Photo: location of the TAG Hydrothermal Field on the Mid-Atlantic Ridge at 26 degrees North. (Google Earth credit)
The first cruise was on board a German ship, the Meteor. The second cruise was on board the James Cook, the oceanographic ship based at the National Oceanography Centre of Southampton. The two cruises are involved in the project Blue Mining, an European Commission funded program (www.bluemining.eu) which aims to provide breakthrough solutions for sustainable deep sea mining.
Photos: The two ships. On the left, the Meteor docked in Barbados, on the right the James Cook docked in the Azores. (Iain Stobbs credit).
My colleague Iain Stobbs summarizes the cruise in his own words and explains his PhD project. I let him speak:
“My PhD research is focused on deep sea mineral deposits known as seafloor massive sulphide (SMS) deposits, these deposits form a result of ‘hydrothermal’ fluids moving through the oceanic crust, scavenging metals from the crust and then depositing them in mounds on the seafloor when they seep into the ocean. “
“Often one of the most important parts of geology research is fieldwork, when the rocks you are looking at are on land, it’s relatively simple to organise and you can go look at them in person. However, as a geology PhD student who is looking at rocks which are below the seafloor and under 3,500 m of water, it makes things a bit tricky! That’s why going on research vessels is a fantastic opportunity to get as close as possible to our main areas of interest.”
“Both of the cruises had different aims and different equipment in use, the first cruise, M127 was focused on ‘exploration’, essentially trying to develop techniques to image and find these extinct SMS deposits which are difficult to find in comparison to the active systems. The second cruise, JC138 was focused more on interpreting the geology and drilling of these extinct deposits. “
“My main role on the M127 cruise was helping my fellow NOC PhD student Adeline Dutrieux with the gravity coring operations. Each gravity core operation took approximately 3 hours and it was only once the corer was back on deck that we found out whether it was a successful core.”
Photo: A scientist hold the gravity coring device before being released. The device consists in a 500 kg head and a long 3-m liner. By gravity, it will dip into the sediments at 3500 m in depth. These sediments will be kept inside the liner until back on deck. (Adeline Dutrieux credit).
“Once the core was extracted from the corer we cut them into 1m sections and transported them to the cold laboratory, kept at around 4°C to mimic bottom ocean temperatures. Processing of each core was would often take several hours. In the cold lab, we extracted the pore waters.”
Photo: Cold in the cold lab while I, Adeline, am currently extracting the pore fluids from the cores with a syringe! (Adeline Dutrieux credit).
Photos: On the left, two scientists (Adeline and Sofia) take care of the cores. They split it in two before subsampling and photographing. On the right, what an example of the cores! It has a very changeable lithology (different material). (Iain Stobbs credit).
“Then it would be split and described before the sediments were further subsampled, photographed and then stored. We often attempted 3 or 4 cores in a row and operated overnight which fitted in well with the other operations being conducted throughout the cruise.”
As Iain said earlier, the main aim for the Meteor cruise was the ‘exploration’. A AUV (Automated underwater vehicle) called Abyss did several dives to realise a very high resolution bathymetry map of the field. During her 10 hours dives, she collected depth measurement but also magnetic data and self-potential data. On board, the scientists processed these data and brought us a new view of the bathymetry. We could distinguish a difference of depth of two objects at 50 cm apart!
Photo: Abyss is launched from the back of the ship at night for a 12 hours dive. On the right, a high resolution bathymetry map of the area of interest. The purple colours express the deepest environment. (Adeline Dutrieux/Iain Stobbs credit)
Photo: Abyss waiting for her recovery on deck. (Photo: Adeline credit).
Also, we virtually dived with HyBIS. HyBIS is for Hydraulic Benthic Interactive Sampler. It is a simple quite already technological robot-like instrument. It can dive up to 5000 meters-depth and can collect samples from the seafloor. On the Meteor, the HyBIS was equipped with a shovel who collected mud, sediments and oxides fragments. The main purpose of this action was to recognise other inactive hydrothermal mounds. We did find a large one, particularly promising and called it Rona Mound in honour to Peter Rona who spend long years of his life working on the TAG Hydrothermal Field.
Photos: On the left, HyBIS comes back on deck with his shovel full of mud. On the right, the scientists Sven Petersen and John Jamieson collect the mud delivered by HyBIS. (Adeline Dutrieux credit).
Photo: Here are the few oxide crusts being washed. (Adeline Dutrieux credit).
Photo: “My view of the early morning sky while manning a test of the parasound, an instrument which can provide information of the amount of sediment cover on the seafloor.” On the left, every two or three days, if the weather permitted (not too hot and not too windy), we entertained ourselves by doing work out in the evening. We must keep fit while we are stuck in a narrow environment. (Iain Stobbs credit).
“After a 10 day break in the Azores we were ready to set off on the James Cook for JC138. A main difference between British and German cruises is that the British cruises often operate on a shift system, compared to the German approach of ‘work when needed’. Therefore we sorted out shifts and split the geological team so that we could theoretically work for 24 hours solid between us. My main roles on the JC138 were to log, photograph and document the recovered drill core and to undertake interpretation and geological mapping of extinct mound using video footage obtained from our HyBIS (Hydraulic Benthic Interactive Sampler) remotely operated vehicle, which also collected a few surface samples. Ultimately the intensity of work associated with my logging role was dictated by the success of the rock drilling, which encountered a wide range of problems across the cruise. This shows the difficulties with conducting research in these extreme environments, however, by the end of the cruise almost all of the problems encountered were overcome enabling recovery of core material from three different extinct SMS deposits.”
Photo: The main lab is home of the HyBIS control. We have three cameras set up on HyBIS and two technician control the action of the propellers as well the length of the cable out to move HyBIS in any direction. (Adeline Dutrieux credit).
Photo: The Rock drill (RD2) belonging to BGS (British Geological Survey) comes back on deck after drilling sometimes up to 48 hours non stop on the seafloor. (Adeline Dutrieux credit).
“Our main findings from the drilling campaign was that at all three drilled mounds, the same sequence of rocks was recovered, this include a very hard, possibly relatively impermeable layer of silica and iron rich rock. This layer was directly overlying the massive sulphide minerals at depth, and is now one of the main focuses of my research.”
Photos: On the left, the core lab set up and ready to welcome any core from the rock drill. We see the core trays, the core splitter on the left, and a photography lab has been mounted in a corner. On the right, an inactive partially weathered sulphide chimney located on the edge of one of the extinct SMS deposits sutdied. The high quality of this image, obtained from the hyBIS HD camera, enabled mapping of the area. (Iain Stobbs credit)
Photo: Examples of the drilling cores. The top of the core is on the top left of the rack. It shows first a red rock rich in Fe and silica, followed by massive sulphide mainly consisting in pyrite and chalcopyrite.
“Now that I’m back ashore I can start with some of the more hand on side of my research, my sample have been cut and are being prepared to be made into thin sections. I can then look at these under a microscope and try and work out what minerals make up my samples. So once I know what my samples are made of, I can try and work out how they formed and then try to understand the processes that were ongoing to form these rocks.”
More detailed blogs written by our scientific crew over both cruises can be found on the project website (M127: http://www.bluemining.eu/researchcruiseblog/, JC138: http://www.bluemining.eu/research-cruise-2-james-cook-138/).
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]]>For me, oceans are MYSTERY. Light disappears rapidly in depth, after 1000 meters, it is the absolute darkness, deep and unknown. I chose this picture of a ROV (remotely operated vehicle) surrounded by this obscurity. Thanks to it, light is brought in the most obscure parts of our planet, and discoveries are infinite. 
(Image credit to NOAA )
For me, oceans are LIFE. Without oceans, life would not have appeared on Earth. The oceans also host spectacular ecosystems independent from the sunlight, such as the hydrothermal vents communities.
This is a picture I took when I was diving in the Red Sea. So much life in one picture – fishes, but also numerous corals forming the reefs.
For me, oceans are FREEDOM. Although, it is not yet weightlessness, it is only in water that you feel free of movement, you suddenly feel light. Thanks to the current technologies, you escape from the busy human life by diving into the blue. It is a privilege to explore it by yourself.
Again in the Red Sea – feeling free …
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]]>Read me to know a bit of life of one of your mentor!
Since I was young, I’ve been attracted to the seas and oceans. I scuba-dived for the first time at the age of 10. I am now 25 with hundreds of dives and I definitely linked my life to the marine environment. But being in water wasn’t enough, I wanted to learn more. I then studied geology for five years at the University of Liège – in Belgium, where I come from – with the intention to keep going in oceanography. I followed some lectures dedicated to oceanography, such as the marine sediments module. At the end of my bachelors degree, I took part in a multi-disciplinary summer school at STARESO (the marine scientific station of the University of Liège in Corsica) from where I made some wonderful memories and learned a lot about all facets of the marine sciences.
The STARESO scientific station dedicated to marine research located in Calvi Bay (Corsica). (c) Adeline Dutrieux
During my Master degree, I however followed the geochemistry path of continental rocks with my thesis focusing on lava rocks from Chilean volcanoes and their volcanic geochronology. In my opinion, rocks were far more fascinating than sediments.
When I‘ve graduated, I took part in a Summer school in Bremen, at the MARUM institute (Germany) and I discovered the fabulous world of cruises with the IODP organization. Since this time, I knew I wanted to be part of the marine research network. Where can we work on rocks and in a marine environment? Multiple choices, but the hydrothermal systems with their black smokers and their mineral resources got my attention already for a couple of years. I then started to look at a PhD program suited to my ambitions. I heard of the National Oceanography Centre and their long list of available PhD projects (I recommend you to have a look if you wish to do a PhD). And do you know how? Thanks to Future Learn and this exact same online course Exploring our Oceans!
I applied, got an interview and here I am :-). I am now in my second year, looking at the interactions between the massive sulphides (a type of marine mineral resources, particularly interesting for Cu and Zn mining), the interstitial waters and the surrounding sediments at a hydrothermal field (TAG). This TAG field is located in the middle of the Atlantic (literally, at 5 days of transit of the closest island in the Azores!). I spent this summer 2016 there, three memorable months, on the research ships the R/V Meteor (German ship) and the RRS James Cook (based at the National Oceanography Centre), I met new colleagues, made new friends, and acquired a lot of experience and knowledge. 
Me on board the James Cook, having fun with sediments containing a very high iron content… explaining tenacious red stains everywhere ! (c) Adeline Dutrieux
I made a drawing of my two cruises showing most of the instruments we deployed and many features describing my three months
Two ships on the Atlantic Ocean, plenty of instruments deployed on the seafloor, HyBIS ROV surveying the field, red iron sediments in the inactive hydrothermal mounds, plenty of wonderful sunsets/sunrises on the Meteor! Sandy beaches and jungles in Barbados, cloudy calderas in the Azores, flat sea surface on the Mid Atlantic ridge, the hyper active black smoker, the stunning meteor shower Perseid in August. (c) Adeline Dutrieux
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