A Pyrosoma colony trapped on top of the CTD
Siphonophore pictured at an ROV dive
Date:July 13, 2004
Author: Ingvar byrkjedal, Bergen Museum, Norway and Andrey Dolgov, PINRO, Russia
Trawls, ROVs, and such
Ocean scientists are gadgeteers, there is no doubt about it. They marvel over state of the art equipment. Coming across them in corridors or on deck, you hear them discussing the most complex details of their sophisticated gear. It is often amazing to witness the ease with which most of them seem to be able to enter an ongoing discussion; apparently the level of knowledge about their technical tools is well developed in these people. Those of us having a slightly different background are truly impressed. Yet, their proficiency in this field is only reasonable. Next time you sit in an airliner looking down on the landscape beneath you, imagine how it would be to study birds by lowering a net to treetop height! At that moment one starts to appreciate how enormous a vertical distance of 3000 - 4000 metres really is, and it is equally apparent that gear matters.
At this cruise we frequently operate at the edge of what is possible when it comes to gear. Of course, our results are strongly dependent of proper functioning of same. You can tell from the faces where there have been successes and failures. After the recent days of excellent video tapes from the ROVs, everyone have been in a high glee, jokes and merry comments abounding. We have been glued to the screens watching all the exciting transmissions from the secrets deep underneath us. Alas, today there was a regrettable setback: The engine of the once so promising ROV Bathysaurus refuses to work, and this seems to be definitive. There are many wrinkled and stern faces as one discusses various options. But we still have the ROV Aglanta, which can be employed for less deep dives. Using the Aglanta, our present ROV strategy is now to compare areas east and west of a deep through dividing the southern box in which we are still working.
Sometimes, however, our gadgets provide us with a bonus. Today our CTD, after having done its intended job in the depths, was hauled with a 2 m long Pyrosoma colony wrapped around its top!
For the first time during the cruise we obtained an ISIT profile. An ISIT is an instrument designed to video-record bioluminescence, i.e., light produced by organisms, as they hit a meshed screen. A device like this gives a nice supplement to other visual recordings for estimation of animal abundance. Most of the light-producing organisms recorded by the ISIT are tiny zooplankton, but they really put on a spectacular light show, making the video footage from the ISIT look, most of all, like a New Year's fireworks.