Box coring the deep-sea floor
On Saturday we deployed the box-core over a potential cold seep area SW of South Georgia Island. The box-core is deployed vertically to the seafloor, where the box enters the soft sediment and takes a large sample of sediment. When the box-core is back on deck, the water on top of the sediment is carefully taken out with plastic tubes as to not disturb its surface where most of the small animals and the organic matter that has fallen from the water column to the seafloor is found. Ali and Rob sampled the box-core with plastic tubes, which they will use for analyses on sedimentation rates. The, Ana, Alex and Eva got their hands in the cold deep-sea mud to look for any animals. We found a few polychaetes (worms) and a little shell...but more specific results will need to wait until the laboratory analyses are made back at home!
Deep-water corals and long-line fisheries
The last 2 days of the cruise have been spent swathing and SHRIMPing over an area of deep-water corals between 1000 to 2000 m depth, close to Shag Rocks, 10 hours northwards from South Georgia Island. Alex was interested in surveying these deep-water coral communities, because the corals are caught as by-catch in the deep-water fisheries of the area.
We first conducted a swath survey to obtain good maps, and then deployed SHRIMP for 18 hours in two days. We saw beautiful gardens of deep-water brown gorgonians, white and delicate Stylasterine corals and a variety of other smaller yellow, orange and purple octocorals, together with sponges, bryozoans, yellow stalked crinoids (sea lilies) and sea echinoids (sea urchins). Sadly though, we also saw evidence of long-line fishing and even saw several borken long-lines that are used to fish toothfish. These studies are important as they provide the necessary information to then work with the fishing industry, governments and non-governmental organisations groups to develop management and conservation options.
This has been a truly fantastic cruise! We look forward to coming back next year with the ROV Isis to survey the study sites in detail, map the habitats and collect samples of water, sediment and animals to describe the ecosystems and understand how they work.
As it is usual in all cruises, the Principal Scientist, Rob, organises a small end of cruise party, with a nice dinner prepared by our chef and cooks. Before dinner, we were delighted to read the winning poems of the poem competition that was held at the Twyford St Mary's School, Twyford, Winchester. We have been very happy that you have been following our expedition on the web and would like to thank all the kids for the lovely poems and drawings!
We hope that you will join us again next January for more exploration and investigations of chemosynthetic ecosystems south of the Polar Front!