JR224: Chemosynthetic life in the Antarctic


 JR224



Cruise diary


Monday 26 and Tuesday 27 January 2009
Location: Southern Ocean (56ºS / 33ºW)

The search for vents continues...

On Monday we conducted a detailed survey of the study doing CTD “tow-yo”, where the CTD is brought up and down in the water column, measuring its conductivity, temperature, depth, and the concentration of particles in the water with additional sensors. The variation of the readings of these sensor tell us if we are going through a different water mass, such as for example a hydrothermal plume with higher particle concentrations than the surrounding water. Doug and Sarah, with help from other scientists on watch, conducted this 20 hour long CTD tow-yo survey and narrowed down the area of potential vent location.

Once the CTD survey was finished, SHRIMP was deployed. SHRIMP is a large rectangular frame with 3 video cameras and lights that is towed on the side of the ship at around 3 metres above the seafloor. SHRIMP has a conducting cable, so the video being recorded is seen in real time on the monitors in the ship's laboratory. The seafloor of the first SHRIMP survey was composed of pillow lavas with more or less sediment, depending on the area. Pillow lavas is solidified lava with tubular forms –  like toothpaste coming out of the tube. They take this shape because during underwater volcanic eruptions, the outer layer of the fresh lava solidified rapidly in contact with the deep-sea cold water, forcing the molten rock to start new pillows instead of merging into a steady flow.

In this SHRIMP survey we have seen some beautiful deep-sea animals, such as bottle-brush corals (Octocorals), glass sponges, small ophiuroids, beautiful sea stars with many long arms, crinoids, anemones and some rat tail fishes. Most of the invertebrates are sessile, which means that they are attached to the rock, and filter feeders, taking advantage of the currents in the ridge that supply the animals with food in the form of particles in suspension.

We have not found the hydrothermal vents yet, but our quest for black smokers and the potential exotic animals that colonise them continues!


Right: The team closely monitor the data from the CTD

Left: SHRIMP being prepared for deployment.

Left: First images of the seafloor from SHRIMP: plillow lavas, typical of mid-ocean ridge settings.

Left: Black-browed albatross and penguins

 


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