Introduction

Diary

Participants

 

R/V Pelagia Cruise HERMIONE /CoralFISH
	Diary overview
Wednesday, 28 October	The BOBO-lander, finally recovered in the dark night…
In the early morning we arrived at the Whittard Canyon about 400 km south of England. The Canyon consists of a couple of deep “gullies” along the slope between the shallow (500 m) continental shelf and the deep sea (4000 m). They form the connection between the productive shelf sea and the relatively poor abyssal plane. It is assumed that they are not only a major transport route for sand and clay, but alsofor organic matter that is the food for the bottom fauna in the deep sea. Their length is about 120 km. The dimesions of these canyons are similar to or even greater than our largest canyon on land, the Grand Canyon. At the continental margin the deepest part of the canyon is quite narrow, only 200 m. Here Henko planned to deploy a BOBO-lander for a year. The instruments fitted on the lander provide measurements of current speed, turbidity, salinity and temperature.
The sediment trap collects the particles depositing from the water column to the bottom. These data hopefully contribute to the knowledge on the transport through the canyons, a process focused at in the HERMIONE- project. After the last preparations, the lander was successfully deployed at 09:00. Finally its position at the seabed was estimated by a triangular acoustical ranging.   In the mean time the normal activities on board have been started. Gerard and Thalia tried to create maps of the Canyon area and of the survey area of the next BIOFUN-cruise in the Mediteranean. Marc and Magda sorted through the rest of catch of the last 3 m beamtrawl. Inge compilated a videoclip of the predators on the mackerel-baited pole on the ALBEX-lander that had been deployed five times in the Belgica Mounds in the CORALFISH-project during the last week. Rachel prepared her paper on the consumption of vegetables by rattail fish. Nanne continued his incubations in the cool-container at the aft deck. The technicians prepared the next BOBO-lander for the deployment in the deepest part of the Canyon planned for tomorrow. The ship headed south to the deepest part of the Canyon.   Then Henko decided to go back to the deployed lander since its position seemed to be wrong: the depth appeared to be only 500 m in stead of 1000. It had landed by accident at the slope of the canyon. Within the last few kilometers off its estimated position Bob started a new acoustical ranging. The results were unexpected and we became suspicious. It was off position and thus had possibly gone adrift!! We tried to verify its position and finally after a wild chase we were able to approach the lander and to release the last weight. This position was about 6.5 km west of the original deployment site. In the dark and foggy evening ten pair of eyes tried to spot the now nick-named GOGO-lander and James saw the feeble flashlight at first. Soon the lander was retrieved and safely tightened on the aft deck.The temperature data learned that the lander shortly after its arrival at the seabed had taken off and had floated in the upper water layers. Luckily we came back after just a few hours in stead of a year!!!   Magda Bergman