LOTUS · Long time-series undersea surveillance

Final Activity Report Summary - LOTUS (LOng Time-series Undersea Surveillance)

The deep-ocean contains the largest habitats on Earth, covering more than 60 % of the planet's surface. The deep-ocean is very poorly understood. In particular, we know very little about long-term changes in the deep-water environment. This is a problem because fishing and other industries are moving into deep-water systems. It is very difficult to monitor or predict future environmental changes as we do not know how the deep-ocean varies naturally. The LOTUS project was designed to allow Bailey to learn about the latest techniques in deep-water long-term monitoring, and to conduct his own research on deep-water monitoring. This work was carried out in Dr Ken Smith's laboratory at Scripps Institution of Oceanography (part of the University of California, San Diego, United States). Dr Smith has been operating a long-term deep-water study site in the North Pacific since 1989, and is considered the world-leader in this type of work. The site, known as 'Station M' is 200 km west of California, in a depth of 4 100 m. I spent two years working in California, and took part in seven research cruises to station M. During most of these cruise I used a video 'lander' to observe deep-water fish and to record their swimming performances. The lander was baited with mackerel fish and dropped from the research vessel to sink down to the bottom. When it reached the bottom its computer activated itself and began recording the fish as they came to feed at the bait. At the end of the experiments, I sent an acoustic signal to the lander. This made it drop weights and float back to the surface, where I would open it up and remove the video tape so that I could watch it later. As well as analysing the videos from the lander I studied photographs taken with a camera sled. The sled was towed along the seabed, taking photographs every five seconds. I used the lander videos and the photographs of fish taken by the camera sled to work out how many fish live in the area around station M, and how these numbers have changed since 1989. What I found was very surprising. Numbers of fish were three times higher in 2004 than in 1989. We think that the big increases in fish numbers were caused by fish moving into our survey area. This is probably a natural change, driven by the El Nino cycle. This cycle causes changes in the temperature and fertility of the sea surface, and this in turn affects how much food reaches the deep-ocean floor. Most of the animals in the deep-ocean get their food from animals and plants which lived near the surface (4 000 m above in this case), so changes at the surface can have big effects on deep-ocean animals. It appears that numbers of fish are falling again now, and this is probably a normal part of the life of the deep-ocean as fish move around the seabed in search of the best food resources. This was a very exciting discovery and was covered by the Discovery Channel, National Public Radio and many commercial radio stations. My work on the long time series study fulfilled the first objective of my study, although due to forces outside the control of the project partners some of the equipment expected was not available. The results of the work were however much more interesting than had been expected and will contribute to at least one further high profile paper. The self-contained aspects of the project which formed the second objective were also successful and a large amount of high resolution data on deep-water fishes was collected. Some of this data has been analysed and I am in the process of writing the relevant research papers.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз