JC010: Mud volcanoes and submarine canyons


 JC10



Cruise diary


Day 19: Tuesday 29 May 2007
Position: Latitude 35º, Longitude 8º, Bearing 346º
Weather: Sunny and windy


Gill and Eduard write:

"Just as Isis was finishing its dive last night it spotted one of its most amazing sights yet. A tripod fish was standing on its fins absolutely still, waiting for a tasty meal. Then, a wonderful toadfish, which looked highly startled by the camera lights!  Not what it would be expecting at 2200m! It had such a fantastic face; full of character. Carlos Ribeiro has proved to be full of treasures.

Late last night, Ann from Gent University collected her push core from the ROV dive. She is working on the meiofauna – animals of 32 microns to 1 mm, found in the sediment. These are animals which are larger than bacteria but smaller than the larger megafauna, which are things like crabs and fish. The most numerous of these are a large group of animals called Nematodes (the common name is round worms). Of all the animals of this size found in the mud they make up 95%. How does Ann collect them? She uses the video transect from the Isis and selects interesting sites. She has to do this because the environment is so patchy. An interesting little bit of  habitat (microhabitat) next to a cold seep or a bacterial mat may be just what she is looking for. The method of collecting the animals is by using a push core on the Isis itself, which does exactly what it says - push into the mud and collects it to bring it up to the surface. As you can see from the clip once up at the top Ann, and Katja who is a geochemist, work together on the sample. Then Ann slices it up and preserves it in formaldehyde, as you can see in the photographs, so that when she gets back to Gent University she can count how many and what type of organisms she has in her sample.  The sediment is often very smelly and toxic with no oxygen and high in sulphides which are very poisonous to us and yet they can survive. In fact they thrive here much more than in most deep sea habitats. How? Maybe they can migrate in the mud, coming up for oxygen and going down for food substrates. Scientists like Ann are still looking for the answers.

Ann preserving nematode specimens for work back on dry land

Ana wrestles with a push core

Spooning the sediment into the sieve

Washing the sample through a fine sieve...

....with a mesh size of half a micron - that's very small!

Meanwhile other push cores are being processed by the other biologists. You can see a video clip of Ana at the washing table sieving for macrofauna, animals over 1mm from the top 1cm and 5cm! It was a beautiful day. Perfect for this, with the sun pouring onto the deck. She will see if there is anything alive in the sieved mud. Most of what she is looking for will be in the top 1cm.

Well only three more days! We need to make the most of it. The adventure will soon be over. We are now steaming off to the next site. More reporting tomorrow.

Retrieving push cores from Isis

Ana washing out samples from the push cores



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