CD179: Deep-sea biology of the Portguese canyons


 


Daily diary

Thursday 27 April 2006


Abi writes:

"Another 24 hours has been and gone, and what a day it was!  Last night saw the successful completion of two megacore deployments for Dario and Xana.  This involved sieving mud, which, as any seadog worth their salt will tell you, is a fun-packed experience.  Each of the 8 cores per deployment is sliced into sections; 0-1cm, 1-3cm, 3-5cm, 5-10cm, 10-15cm and 15-20 cm, and the 8 slices for each section combined.  Each section is then sieved through a 500um and 300um sieve, so that Dario can not only look at geographical distribution of macrofauna, but also the distribution with depth through the sediment.  Mud is rather gloopy at the best of times, but the deeper the section of the core, the more dense, sticky and clay-like the mud is.  This makes it very hard to sieve, and some members of the team devote a portion of their time to kneading the mud into more manageable lumps.

The amphipod trap was retrieved this morning.  After its acoustic release from the seafloor was triggered by Ben, we all went up to the bridge to see if we could spy it bobbing about.  Half an hour and seven scientists and crew with binoculars later, we still couldn’t spot it.  Fearing the worst (that the whole trap had been eaten by a giant amphipod-eating monster), and knowing from the transducer signal that it was only a few hundred metres away, we squinted hard and were finally rewarded by Dave Billett spotting it and then promptly losing sight of it.  We eventually managed to get it on board, only to find a disappointingly meagre smattering of amphipods.  It would appear that they aren’t fond of smoked kippers, and that mackerel is more their bag.  So when we dock on 1st of May to swap some of our scientists we will be met by Xana’s mother (who luckily lives in Lisbon) who will have been dispatched to the Sunday market in search of these fussy eaters’ breakfast.  Better luck next time on that one. 

Before and after photos of the sumptious kipper buffet snubbed by the amphipod elite,
who are clearly used to a more highbrow mackerel spread.

Retrieval of said kipper buffet (or amphipod trap).

As I write, we have just completed the first of this evening’s megacore, and are waiting for the second to come in.  Later on in the evening we’re deploying the Agassiz trawl, to see what we can drag up from the depths.  Many fun hours of sorting through squashed animals to come..." 



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© Challenger Division for Seafloor Processes
April 2006
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