Today we are heading west from Bantry Bay towards the Mid Atlantic Ridge.
At 3am we deployed a hydrophone that will be towed by the ship between sampling stations. The hydrophone is set to a medium to high frequency range so lower frequency dolphin whistles and high frequency whale clicks can be recorded along the way.
After thunder and lighting in the early hours the day has turned out to be sunny and calm - perfect weather for marine mammal watching. This started with an early morning sighting of an Atlantic white sided dolphin. Within the next hour Mick Mackey had seen about 8 pods of Common dolphins, some swimming right up to the ship!
As we crossed the continental shelf, moving out into deeper water, we spotted a few blows and the flukes (tail fins) of 5 Sperm whales just a couple of miles from the boat.
The day was also good for bird spotting - especially for shearwaters; Mick spotted a Great shearwater (Puffinus gravis) and a Sooty shearwater (Puffinus griseus). These are likely to be migrating northwards from the island Tristan da Cunha, in the South Atlantic. Also, from Europe, a Manx shearwater and a Cory shearwater were seen.
In the afternoon, the acoustic releases for the landers were tested. To do this, the releases were attached to the side of the CTD rosette which was deployed to a depth of 3000m. An acoustic release signal was then sent, the CTD recovered, and the releases checked for successful release. These tests should ensure that the landers we deploy to the deep sea are able to release their ballast and return safely to the surface for recovery, and don’t get stuck down there!
Jessica Craig 16 July 2007
PhD student (Oceanlab, University of Aberdeen)