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Atlantic coccoliths blog

Sampling

Martine, Monday 13 October 2008

Already a week since we left the stable land for the not-so-quiet sea. Time flies out here even though we have already gained 2 extra hours by sailing west, towards the sunset.

After a rough beginning of the week, the weather cleared up and the sea is more gentle now. We have settled into a sampling routine, usually with 2 sampling stations a day, one before dawn (unnaturally early according to Jeremy), the other at midday.

Sampling begins with the rosette sampler being lowered down through the upper 300m of water. It carries 24 bottles, each of which has an individual firing system to collect the seawater at specific depths.

The rosette sampler and other devices for recording water properties

The rosette sampler and other devices for recording water properties

Because the weather is now better, we can secure the rosette on the outside deck between samplings. This makes our life much easier when it comes to recovering the water. When the weather was rough, it had to be secured as soon as possible in its ‘cabin’ where it fits tightly, and half a dozen scientists would try to get in as well to recover their samples.

The rosette sampler returning to the deck at dawn this morning

The rosette sampler returning to the deck at dawn this morning

After recovering the seawater, our main task is to filter it. We have to do this in several different ways depending on what we are trying to find out. First of all we look at a small syringe filter under the microscope to decide the volume of water to filter. We use membranes with holes that are 0.2 or 1 microns wide (a 10,000th of a centimete) to filter the water. The process takes place in a vacuum and we use a recovering flask called a carboy.

While Jeremy set up the microscope in the dry lab, I played with tubing in the wet lab to set up our filtering system. Unfortunately our carboys were not delivered in time, so I tried (unsuccessfully) to use a fermenting cask. It collapsed. Then I tried a thick plastic flask. It also collapsed. We managed to borrow a 20 litre heavy duty carboy from Glen Tarran (a colleague from Plymouth). Fingers crossed, this one is still alive and healthy…

The sampler is relieved of its watery load

The sampler is relieved of its watery load

Because our 2 filtering ramps are on 2 different benches I had fun playing with tubing, connections and taps to connect everything. The best thing is that Jeremy loves to come and watch all the bubbly tubing!

We have now tried all our protocols and are ready for intensive sampling to produce LM (Light Microscopy) and SEM (Scanning Electron Microscope) slides, bulk and probe DNA samples, and other samples, during the second part of the cruise, south of the Azores.

A happy Martine surrounded by the filtration kit in her lab

A happy Martine surrounded by the filtration kit in her lab

Martine, off the Azores

Posted in Equipment

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