Diatoms from northern atlantic plancton sample

[MicroBob]

Hi together,
yesterday we had our group meeting in Hamburg and had especailly much fun in observing a placton sample, concentrated and conserved, from the northern atlantic, about 400km south of Greenland.
today I washed the dried sample of tree slides, removed water and alcohol and cleaned the diatoms a bit by heating in an oven to 450°C. Then I mounted them in Pleurax.
Here I show a couple of photos of these diatoms.

Bob

[Hobbyst46]

Impressive, Bob!
Did the samples contain zooplankton as well ? if so, were they just burnt out in the oven ?

[WhyMe]

Very nice!

[MicroBob]

Hi together,
this was a complete catch, including zooplancton. I think I saw parts of it reduces to ashes in the slide. This material is from dried out slides from yesterday and I don't know what harm has been inflicted by drying under the cover slip, centrifuging and incinerating at 450°C. I still have a couple of drop of the conserved material but I have to think about how to make best use of it. A draw of an 80cm plancton net of such an expensive research ship doesn't contain much solid material so supply is limited and precious. I attatch an image taken with thee 2,5:1 Plan objective to show the general condition. The interlocked Biddulphias looked much better in the wet conserved material than in this slide.

Bob

[MicroBob]

I also had a lot of bubbles in the diatoms, which I had not experienced befor in this amount.

[MicroBob]

Hi together,

And here another picture. The long arms offer resistance in the water, as far as I know to reduce sinking.
While the cleaning by incineration doesn't work too well it helps to keep colonies together as they are in fresh condition. The individual alge in a chemical cleaned material is for me often very difficult to put into relation to its live look.

Bob

[MicroBob]

And here a colony that stayed together in cleaning.

Bob

[Hobbyst46]

They only get better!
Bob, please disclose the optics - is it a plan 100X oil and a darkfield oil condenser ?

[MicroBob]

Hi Doron,
these were either taken with the Plan 40 or Zeiss Jena Apo 40/0,95 and DIC.
When everything fits perfectly the DIC should give a black backgroung in the medium position of the analyser slider. I only get a medium dark grey with my equipment.
Then I used gimp to make the background dark and adjust the light areas.
I actually took stacks of images but didn't find the time to process them.
The cleaning and mounting had to be squeezed into a day with a lot of work. I just was curious how well the cleaning worked and how good the diatoms look afterwards. This was medium successful: Some great diatoms from the fresh sample were not really presentable afterwards, some others were. What I like a lot are the diatoms with fine spines, I never had them before in a slide.
I have prepared slides from diatom material from nova scotia - completely different species though not from that far away from the point were this sample was fished.

Bob

[MicroBob]

And the last one, looking like a fish bone.

[Hobbyst46]

Terrific!

[WhyMe]

Very impressive!