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.
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
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.
