Monday 31 December 2007 à 14:28

First deep trawl

Sophie Mouge. Correspondent aboard the Aurora Australis

At three o’clock in the morning, the night shift is stamping their feet. The trawl is currently turning. It has scraped the bottom at a depth of 1,200 m, the deepest we’ve gone to date.

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Monday 31 December 2007 à 14:18

Data for the Aurora Australis at 12h30

Sophie Mouge. Correspondent aboard the Aurora Australis

Position of the icebreaker:
- latitude: 66°43.800' S
- longitude: 144°58.740’ E
Wind:
- direction: SE
- speed: 18 knots
Water temperature: -0.5°C
Air temperature: -2.2°C
Atmospheric pressure: 980 hPa
Relative humidity: 97.5 %
UV-B: 2.2 W/m²
Water depth: 630 meters
Sunrise: above the horizon all day

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Monday 31 December 2007 à 13:53

Position of Aurora Australis

Sophie Mouge. Correspondent aboard the Aurora Australis

FROM: Martin Riddle
DATE: 31/12/07
REPORT (SITREP) NO.: 315
UNIVERSAL TIME: 0100
LOCAL (SHIP) TIME: 1200
AUSTRALIAN EASTERN STANDARD TIME: 1200
POSITION: -66 45, 145 18
HEADING: various
CURRENT SPEED (KNOTS): 2.5
DISTANCE TO NEXT WAYPOINT (NAUTICAL MILES): N/A
DISTANCE COVERED LAST 24 HOURS (NAUTICAL MILES): 68.9
WEATHER CONDITIONS: Low cloud, occasional snow and sleet, visibility reduced by snow, wind 15 kts from 140T with gusts to 19 kts
AIR TEMPERATURE: -2.5
SEA TEMPERATURE: -0.5 SEA CONDITIONS: Slight seas, with low NNW swell 1m
ICE CONDITIONS: Scattered bergs and bergy bits, open water.
REMARKS: The epibenthos (seabed surface living animals) at the deep site sampled last night near the Mertz Glacier was relatively low in diversity, and dominated by a few large solitary tunicates and sponges. Some species, such as the green sponge Latrunculia, are found all around the coast of Antarctica and are known from shallow coastal locations as well as these deeper places. The scientific highlight of this site was the discovery on the high definition photographs of highly pigmented patches on the sediment surface. The colour is very like the patches of photosynthetic microorganisms found on sediments in shallower places but at this depth (1300 m) no light penetrates and so photosynthesis is not possible. The most likely explanation is that they are caused by organic material from the upper waters that has sunk to the bottom fast enough to retain photosynthetic pigments. This explanation is consistent with the CTD cast at this site which indicated patches of photosynthetic microorganisms at various depths through the water-column. As I write, these surface sediments are being examined under the microscope to see whether the source of the pigments can be identified.
Regards, Martin and Sarah.

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WEATHER


Water temperature: - 0,5 °C
Air temperature: - 2,2 °C

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