Introduction

Diary

Participants

 

R/V Pelagia Cruise HERMIONE /CoralFISH
	Diary overview
Sunday, 1 November	Angling for the mooring…
It is a nice bright day, and after breakfast we command the releaser of the mooring by means of a sound signal of a special frequency to drop its heavy weight of 260kg. It obeys and by telemetry we notice that the mooring is coming to the surface. It will take about 32 minutes before the mooring has travelled from the 1900m deep bottom to the surface. We are anxiously waiting on the bridge, armed with binoculars. With some luck I detect the two yellow floats at a distance of 1 km first, although I did not put a price on it. At first I am quite happy to see it, but than I notice that I cannot see a flag. When the ship comes nearer it is quite obvious that the upper part of the mooring is missing. It consisted of 2 floats tightened together with a flag and a satellite beacon. The pickup line (a floating line of 25m with an extra float) is also gone. It is therefore quite difficult to pick it up. Bert has to steer the ship very close to the row of floats (diameter less than 50cm) that are bobbing on the surface.
Sometimes 2 to 3 floats are visible, but the other moment it disappears altogether for some moments below the water surface. Arie and Lorendz try to catch it by angling for it with a small dredge on a rope. After 20min trying it in vain Arie has the luck to hook on. Lorendz follows, and both pull it in as far as they can, than the crane takes over and slowly the mooring is hauled in. First the 6 remaining floats, than the first sedimentrap and datalogger are recovered. The 12 plastic vials of the trap all show a few millimeters of deposited material and the fluorometer attached to the datalogger flashes a blue light, which means that they both worked well! After another 100 meters of cable the lower trap, datalogger, currentmeter and both acoustic releasers come into view. All the important equipment is now safely recovered. A big sigh. We have been very lucky. If one more float would have been lost, we would never have found it back. Now we have a continuous record of current speed and direction, temperature, fluorescence, turbidity over a whole year and the flux of material to the bottom for each month of the year. We feel very happy. The rest of the day is filled with video surveying the seafloor with the hoppercamera. In the evening we steam to the location of the 3000m deep mooring. Rachel, our BIOFUN postdoc cannot sleep this night because of excitement of what the next day will bring.   Marc Lavaleye