By Veerle Huvenne
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!