Mar-Eco was an emerging international ecosystem study that had recently received a planning grant as a CoML Pilot Project. It aimed to conduct the first large-scale coherent study along the mid-Atlantic ridge, which was a poorly described environment. The objectives were to estimate regional-scale biomass, map species composition and distribution, identify trophic interrelationships and food webs, and investigate the life history strategies of selected species. The survey would cover the 1500-km from Iceland to the Azores, a poorly mapped area with depths of 500-3500 m characterised by rugged terrain, sea-mounts, steep slopes, hard substrates and variable currents. The project would focus on fish, cephalopods, crustaceans and gelatinous plankton and nekton, and would encompass bentho-pelagic and epibenthic macrofauna, as well as pelagic organisms. There would be a general pelagic survey plus detailed surveys and fishing vessels might be used, although research vessel time was funded for 2002 (preliminary work) and 2004, by which time the new Norwegian RV ‘G.O. SARS’ would be available to participate in the planned multi-ship operation. Acoustic surveys would form a central part of the project, using hull-mounted transducers and multi-beam and multi-frequency instruments. AUVs might also be used and consideration was being given to investigating seasonality, using floats, moorings and ships of opportunity. A planning workshop involving biologists and technicians was scheduled for January 2002. The analytical phase, including submission of data to OBIS, would span the period 2004-2008.

In discussion, Gaby Gorsky commented that he had recently returned from a cruise in the area, which had been devoted to physical oceanography. In response to Julie Hall, who commented that scientists in the Netherlands had experience of deep-sea landers and associated technology, Olav Bergstad said he was already in contact with Monty Priede who had developed the AUDOS deep-sea lander at the University of Aberdeen in the UK. Mention was made of the proposed NEPTUNE cabled instrument system that is projected for studying the Juan de Fuca Ridge. In response to a number of questions from Ken Foote, Olav Godø and Olav Bergstad commented that they intended to use HUGIN, an ROV with a plug-and-play facility and a depth capability of 2000 m although AUVs would be more useful in irregular topography. Most standard acoustic instruments could be plugged in on Norwegian research vessels and three echo sounders could be used simultaneously at different frequencies, although not at the same time as the sonars. Acoustics and optics were both needed to sample jellyfish and cephalopods effectively. Multiple opening and closing nets would also be used and trawling would be possible to 3000 m using very large pelagic trawls towed at 5 knots. It was intended to use standard trawl instrumentation, although this was only rated to 1200 m and, as David Farmer pointed out, there was an important technical challenge to be overcome in extending the capability to 3000 m. Observing and capturing jellyfish and cephalopods also presented a major problem. A number of solutions were suggested, including imaging techniques and ROVs, which offered some catching ability (Gaby Gorsky). A range-gated laser scanner developed at MBARI (Ron O’Dor), offered an exciting way to combine acoustics and optics and compare data at the same range. David Farmer commented that it would be challenging to deploy this instrument underwater, but offered to explore possibilities. On the basis of observing elephant seals at great depths in New Zealand, Dan Costa suggested installing a video camera on large pelagic trawls to investigate deep-water fauna. Julie Hall drew attention to experience of trawling on sea-mounts off New Zealand. Olav Rune Godø commented that the project would include a research vessel cruise in late 2002 to trial deep-water technology.

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