18. June

Todays Highlights

Date:June 18, 2004
Author:  Odd Aksel Bergstad (IMR) and Richard Young (University of Hawaii)

Operations continued in the fascinating area named the Charlie-Gibbs Fracture Zone. Depths reach 3500-4500m in the two main rift valleys running perpendicular to the ridge axis, with peaks on either side as shallow as 800m. The topography is spectacular, and our charts are not particularly accurate. Using the ship’s multibeam echosounder (SIMRAD EM 300) we keep observing and mapping new features not found on the charts.

We’re now close to the sites visited a year ago by the manned submersibles MIR-1 and MIR-2 operated from the Russian Academy of Sciences RV Akademik Mstislav Keldysh. MAR-ECO scientists from Russia and USA dove to 4200 m and explored both the fauna in the water column and near the bottom. Highlights from these dives are found elsewhere on the MAR-ECO website.

We towed the biggest trawl, the Egersund Trawl, in the northern channel of the CGFZ at a depth of about 2000m. The mouth opening of this trawl is the size of a football field, and this is necessary to sample a large volume and to capture fast-moving animals. Spectacular big red shrimps occured in this catch.

The DOBO lander designed by the University of Aberdeen’s OCEANLAB was prepared for deployment at a site in the deepest northern channel. This lander can take still photographs of animals attracted to bait, in this case mackerel. The DOBO will stay out for about a month and be retrieved during the second leg of the cruise. During that period batches of bait will be released at pre-programmed intervals. The whole lander is kept at the bottom by a weight. It has an acoustic  release mechanism, i.e. an electronic device that is triggered by a sound signal. When triggered, the lander comes to the surface floated by its yellow spherical floats.

Weather Conditions

Not bad, bit a little windier than yesterday. It remains cool, and we look forward to warmer weather
when crossing into more southerly waters.

Tomorrows expected highlights

The CGFZ will be crossed but not left for good. This is a transition area where we expect faunal changes as
we move southwards. The sub-polar front usually lies in this area, but due to extensive cloud cover we have
few good satellite pictures to help us locate the front exactly. Hopefully we will have more information from
both satellites and the surface temperature and salinity measurements during our crossing of the main channels.