CD179: Deep-sea biology of the Portguese canyons


 


Daily diary

Wednesday 19 April 2006


Abi writes:

"Today saw the end of the TOBI surveying as we move our attention for the time being to the biology of the canyon systems here.  For the most part the TOBI survey has gone without a hitch, for which we owe much gratitude to the tireless TOBI team.  The survey has revealed indications of submarine landslides in the Sétubal canyon at about 4600m, and massive lumps of sediment in the Cascais canyon at the same depth, that may have been propelled through the canyon from shallower depths.  The TOBI survey of the canyon heads will be a bit of a challenge to interpret as there are so many gullies and tributaries around.  After the end of the survey we steamed to about 3200m in the Sétubal canyon, where we carried out a CTD drop and SAPS, both of which measure different properties in the water column.

We plan to do a lot of SHRIMP-ing (underwater video footage) and mega-coring (taking samples of sediment from the seafloor) over the next few days to look at the mega- and macrofauna that inhabit Sétubal canyon.  Megafauna are animals larger than about 4cm across, whilst macrofauna are animals smaller than this, but larger than about 300microns.  SHRIMP (or Seabed High Resolution Imaging and Mapping Photography) is a towed camera system that will be used to provide video footage and stills of the canyon floor.  These images are what I will be looking at to see how the community structure of canyon megafauna changes within and between the canyons.  Xana and Dario are interested in looking at the macrofauna that may be collected in the mega-cores, so fingers crossed that everything goes according to plan!"


John writes:

"As this is my first scientific cruise,and coming from a medical background into my PhD, my expectations lay in a blank sheet of paper. Now,at the end of our first week at sea, I can say the the RRS Charles Darwin resembles being in a very well run small hospital, with Captain Peter Sarjeant being the Chief Exec. and Dr. David Billett the Medical Director! David is to be found daily from early until late at his ‘desk‘ in the ops room otherwise known as ‘Launch Control‘, keeping us all up to date with projected plans for equipment release and always with a plan B & C as today showed. These plans are always posted on our 'special' notice board; the exit door from Launch Control.

TODAY has been a momentous day for the Biologists; Mud and Polychaetes have been sighted for the first time on the deck of the Charles Darwin following the very successful deployment of the Box Core this morning. The day started rather depressingly with an electrical failure on SHRIMP as she was deployed at 02.00hrs.

The launch was aborted by mission control, and SHRIMP recovered. The fault was a short-circuit in the complex towing swivel that protects the very expensive electrical/ towing cable. The swivel was removed and taken urgently to the 'Engineering Operating Theatre' that stands ready for all such emergencies and where surgeon Lee was waiting. With dexterity that was truly amazing, a five hour operation was performed. The diagnosis was a ruptured oil bladder! Photo 1 shows the recovering patient who is still strapped to the operating box, with nurse Teresa setting up an oil infusion supervised by Surgeon Lee and his assistant Jez on the pump. Shrimp was to be successfully relaunched later in the day,fully restored!

At 03.00hrs plan B went into operation with the deployment of the CTD/SAP at 05.00hrs. To include as much work as possible and whilst waiting for SHRIMP to be retested, the BOX CORE was deployed at noon. To ensure a successful mission in view of the earlier problem two interesting phenomena were noted as show in photos 2 and 3. The first depicts Martin doing an unusual good luck dance on the BOX before lift off whilst photo 3 shows, I think, the Chief Scientist at prayer just afterwards. Therefore as expected not only was the deployment very successful but a super sized core was achieved from the Setubal Canyon floor 3,200 meters below (Photo 4). The biologists were ecstatic and crowded round the core counting surface creatures and deciding where to start with this excellent sediment sample (photo 5.). Within 3 hours the Core was dissected, catalogued, examinations started and the deck washed down!

1. Jez, Teresa and Lee working to fix the pump

2. Getting ready to deploy the box corer

3. Chief Scientist David makes some final checks

4. What a lot of mud!!

5. Great excitement as the contents of the box core are revealed

6. Dave and Veerle (right) give a quick briefing to the engineers

Whilst the Box Core was descending to the Canyon floor, Cheif Scientist David gave a detailed briefing to the Engineering Officers on the HERMES Project, as well as the related programs ,aims and objectives of this scientific cruise.

At 16.00hrs GMT Shrimp was successfully relaunched working perfectly. Subsequently, we all watched 3hrs of transmitted pictures for the Canyon floor, whilst Abi was making copious notes on her observations of this futuristic landscape and perhaps dreaming of a return visit with the ROV next year after analyzing the hundreds of pictures on the still film that she was seen loading in yesterdays diary.

The sun is now setting on us and SHRIMP but before signing off with 2 more Box Cores to come tonight,I would just like to take a moment to express the sincere thanks of all the 'scientific team' from the NOC and beyond,to Capt. Peter and all his team for the superb handling of the ship during some seriously challenging manouvres,to all the deck crew for their support and expertise and to Paul and all his team in the kitchen for to such regular and delicious energy supplies."



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© Challenger Division for Seafloor Processes
April 2006
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