Meteor Blog 6. August: Blackout at the seafloor
Unknown terrain can sometimes cause difficulties: the ROV might loose its visibility or the LIFT can not "lift up" anymore. Petra Ristova reports about work with these instruments at REGAB pockmark.
Does the biodiversity of deep-sea organisms play a role for the climate on Planet Earth? Questions all about marine research will be answered directly aboard of the German research vessel Meteor by cruise leader Prof. Antje Boetius and her crew. In cooperation with the geoportal planeterde.de from 17.08.08 to 24.08.08 they contribute a Science-Blog of METEOR expedition M76/3 GUINECO – MARUM research of fluid and gas seeps on the Westafrican continental margin. Technical highlight of the cruise is the remote-controlled under water robot QUEST4000 by MARUM that will be deployed for taking fauna and sediments samples and conduction of in situ experiments. Go on a dive down to places no other human being has ever seen before: explore the fascinating deep-sea fauna and watch the scientists’ work at gas and fluid seeps deep down on the ocean bottom.
Expedition M76/3b is a collaboration of MARUM – Center for Marine Environmental Sciences at Bremen University and its associated institutes MPI and AWI as well as the French research institute IFREMER and the University of Paris.
More Informationen of the Meteor-Blog, an overview of all contributions to the blog and expedition M76/3B:
6. August 2008 (Author: Petra Ristova)
Today's Meteor-Blog is contributed by:
We are back at REGAB, our main site of research, and the ROV is in shape again for a new dive.
The dive plan is set up and all people and instruments are ready to go. The target of today’s dive is the South-Eastern section of the giant REGAB pockmark close to the mussel beds and gas hydrates, and the aim is to explore it by using various instruments and sampling devices. First we had quite a bit of luck (taking into consideration the big, almost completely unknown terrain we are dealing with) in finding very quickly the right place for sampling: a patchy Vesicomyid Bivalve bed (see BLOG 04.08.08 for explanation).
Picture 1: The MPI and the IFREMER benthic chamber set up next to marker 7 at a Vesicomyid patch. The seafloor is littered with empty shells
Once the target was located, the responsible
pilots and scientists in charge had a lot of work to take all samples and bring
all the instruments to the desired location (Picture 1).
Picture 2: Pushcore sampling. A large ray comes by, attracted by the sampling action
Scientists took turns
working in the main ROV operating room, each one anxious and excited to start
up her/his own instrument (Picture 2). But, when working remotely and in such
unpredictable and harsh environment, unfortunately not everything goes as
smoothly as planned.
Picture 3: What appears as a black out to the ROV cameras are simply mud clouds, caused by the manoeuvring movements of the underwater robot.
The heavy load carried by the ROV required usage of
thrusters, which on the other hand disturbed the fine sediment. As a result,
clouds of dust were formed that dramatically decreased the visibility (Picture
3) – kind of a blackout. A lot of patience and experienced hands were crucial
for working under this kind of limited sight. Finally, almost all the samples
were taken and almost all of the instruments brought back to the shuttle. A few
items stay at the seafloor because the sampling arm of the ROV unfortunately could
not grab anymore. Hence, it was time for the ROV and the LIFT to start ascending
back to the surface. But then the shuttle did not respond to our audio signals
from the ship and the weights could not be released. The reason: The legs of
the lift sunk deep into the seafloor and it got stuck (Picture 4).
Picture 4: View from the ROV: The LIFT with its feet deep in the mud
Really unpleasant situation – a LIFT full with important instruments sitting glued to the bottom of the ocean at depth of 3155 meters. The only option left was that the ROV approached the LIFT, to lift it up and pull the security trigger. It worked out! The LIFT was released from the sediment (Picture 5). Once the LIFT and the ROV were back on board, a long night of work (processing the samples and reading out the data from the instruments) is about to start.
Well, I also have to finish this report and go back to my awaiting work. Till the next time.
Many greetings from us!
Picture 5: The LIFT is freed by the arm of the ROV and safely returning to the ship