CD179: Deep-sea biology of the Portguese canyons


 


Daily diary

Sunday 23 April 2006


Veerle writes:

"This morning started off brilliantly with a flat sea, sunshine and a school of about 25 dolphins playing around the ship! Dolphins love to swim in the bow wave of a ship that’s moving, so they came even closer once we moved between two SHRIMP stations. It was a fantastic sight to see them jumping from the water and at one moment I even could hear their cries.

After such excitement we turned to the next SHRIMP video survey. I’m part of the day-team, so our work starts at 8 am. The night team had warned us already that most of the canyon floor seems to be fairly soft-sedimented with very limited numbers of epifauna (the animals which live sitting/crawling/moving close to the seabed, and which are particularly easy to see with a video-survey). The survey of this morning was planned in fairly shallow waters, close to shore, so we were expecting at least a bit more life. But well, the whole area seemed very muddy indeed! Apart from a few areas with more gravel and some blocks (probably the result of a small landslip from the canyon walls, which was quite interesting for me, because I’m sailing as a geologist), we were mostly staring at mud, mud with some burrows, mud with a lot of burrows and something that appeared to me as being more burrows than mud! The little holes are dug by animals that live in the seabed, such as certain types of crustaceans. We did see quite some fish though, including a few curious sharks. But the most spectacular items during the 3,5-hour survey sadly enough were human artefacts… Besides the ‘fairly usual’ plastic bags, tins and cans, we also found a size 11 sock and a toilet seat, while the toilet pan turned up a few hundreds of meters down the track…

Once SHRIMP had come on deck we steamed to the next working station, where we would take some more mega-cores. Time to take in some sunshine on deck, to finish off the last bits of TOBI sidescan sonar processing, to keep the station list up to date and to play some (computerised) card games. You see, the work at sea on an oceanographic vessel is quite irregular. Sometimes you have to wait for hours for a core to go down to the seabed and come back up again, but once it’s there the 5 people from the day- or nightwatch are hardly enough to get all the samples treated in the correct way before the next core comes on deck. For example, as I’m writing this, the night-team is preparing for the next mega core to come on deck. This night will bring some more mega-coring (if the weather stays fine, there suddenly has been a bit more wind coming up), and then Raquel and I are looking forward to the first piston core tomorrow!"

Dolphins are commonly seen around the ship, but they always cause great excitement!



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© Challenger Division for Seafloor Processes
April 2006
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