Desmidiacea images - Tharandter wood, Saxonia, Germany

[MicroBob]

Hi togehter,
I was sent a sample from a moor in the Tharandter wood, Saxonia. It is very rich in interesting an unusual species.
In this thread I will show a cople of images as time allows.
First is a Micrasterias algae, taken with a NPL Fluotar 50:1 1,0 oil, Zeiss DIC "alt"

Bob

[75RR]

Amazing image

Did they send the sample in the post?

[MicroBob]

Yes, I can show a picture of the transport bags.
They work great, but are not really cheap.
A letter, big one in this case, usually takes 1 day in Germany. So if you do a good timing it is no problem to send a sample. It shouldn't be kept in darkness for too long, not too warm, and get some air as soon as possible. I had my son open the expected letter and put the sample on a window sill of a north window.

I attendend a meeting of a nature protection organisation, our University and our society yesterday where a desmidicea monitoring program for our region was installed. Our university has one of the biggest live collections of desmidiaceae world wide and know how to handle them properly. Unfortunatly the number of different species and individuals in Hamburgs moors has dwindled to next to nothing in the past decades. And micro algae are the food for ciliates, insect larvae, etc., all along the food chain. A EU water monitoring program exists, but it only looks at big rivers and lakes, not at the tiny wet areas were most desmidiacea live. This seem to be a general problem, not limited to our region. After the big decline in insect numbers (minus 75% in Germany), the micro world seems to be the next problem area that will be detected.

Bob

[MicroBob]

and one more...
100 Plan
Gypsum crystals in the end vacuole.

[KurtM]

Fantastic - please keep the desmid images coming! (And yes, please post a picture of the sample bag, sounds interesting.)

[MicroBob]

Hi together,
this time a quite small heliozoa.

Bob

[MicroBob]

Here is a link to a website with a SEM image that explains the woven looking surface of the heliozoa: http://penard.de/Explorer/Heliozoa/Acanthocystidae/

Bob

[75RR]

Very nice! ... and thanks for the reminder, had not visited Penard for too long - those guys take the most amazing images

[MicroBob]

Here is a link where an animate GIF shows the duplication of a Micrasterias algae over about 100 minutes. It is from Gerd who sent me the sample.
https://photobucket.com/gallery/user/pl ... Z2lm/?ref=
Just amazing!

Bob

[MicroBob]

Hi together,
I stacked the micrasterias images and like the image quality even more than the single image.
We will put a bigger version on our website.

Bob

[Hobbyst46]

A very pleasing artist creation!

[Wes]

Hi Bob,

Great images! How do you achieve the blue background? Do you use a lambda plate or you rotate the polarizer and shift the principal prism to get that effect?

[MicroBob]

Hi Wes,
this is a built-in feature of Zeiss DIC "alt". There is an analyser slide in the filter slot in the tube head with a thumb screw that moves the prism. At one end one typically starts with light blue, then dark blue, violet, red, orange... In the middle position the imag is colour neutral, sometimes more like dark field, sometimes with a brighter tone, then the same towards the other end until you end with light blue and an image with the effect just mirrored.

For me the most pleasing effect is often found in the blue region and since I'm no scientist I can play around with the colours just as it pleases me. The blue is especially dark in this image as i underexposed intentionally to avoid too bright highlights that can lead to artefacts in stacking.

@Kurt: The bags are named Nasco Whirl pak (100ml / 4 OZ size). They are not zip-locked but fold over, rolled up and are secured by a metal wire. The University uses them too, probably the professionals choice. https://www.fishersci.de/shop/products/ ... 5/11716873

Bob

[KurtM]

They are not zip-locked...

Indeed, zip-lock bags, commonly assumed to give watertight seal, don't really. I'm an old canoe and kayak instructor among other things, and can't tell you how many sad tales of heartache I've seen and heard about people putting valuables in ziploc baggies only to end up with expensive stuff ruined.

Thanks for the sample bag info!

[Sauerkraut]

I attendend a meeting of a nature protection organisation, our University and our society yesterday where a desmidicea monitoring program for our region was installed. Our university has one of the biggest live collections of desmidiaceae world wide and know how to handle them properly. Unfortunatly the number of different species and individuals in Hamburgs moors has dwindled to next to nothing in the past decades. And micro algae are the food for ciliates, insect larvae, etc., all along the food chain. A EU water monitoring program exists, but it only looks at big rivers and lakes, not at the tiny wet areas were most desmidiacea live. This seem to be a general problem, not limited to our region. After the big decline in insect numbers (minus 75% in Germany), the micro world seems to be the next problem area that will be detected.

There isn't much info on similar monitoring programs in the US, unless maybe one knows specifically where to look. I have noticed that the authorities here simply measure coliforms as the basis for water health in our local river. Well, a friend recently brought me a water/mud sample from that river and there was nothing much to see beyond bacteria. It felt dead. And that's healthy?

Here's an interesting link - a bit long - but at least some scientists are aware of the trend:

https://www.nature.com/articles/s41579-019-0222-5

[MicroBob]

Hi Heather,
that is an interesting report, only i doubt that the relevant persons will read it in time.
In the past there has been a lot of research on algae and other micro organisms in the water, but what has been missing is a continuous monitoring and an alarm level to react in time. So it is likely that there is a new monster is raising it's head...

But the problem can not be everywhere so I post one more picture, a big ciliate.

Bob

[MicroBob]

Hi together,
here is a video of this interesting ciliate that shows more of it's behaviour. I have never seen anything like it before, but is is common in the water it is from.
https://vimeo.com/355850812

Bob

[MicroBob]

Hi together,
I spent some more time with this interesting sample.
One thing I tried but didn't really mange so far was to get a good stacked image af a Micrasterias that is not lying flat but in a nangle to the cover slip.
Then there is a picture of the housing of an amoeba.

Bob

[75RR]

Again very nice! Lovely Micrasterias

+ It looks like the amoeba house/shell/test is made up of diatoms!

[Hobbyst46]

Hi Bob
The Micrasterias photo is very beautiful.

[MicroBob]

Hi together,
I have seen pictures of amoeba housings that are made from diatoms, but in this case I can't see a clear sign of diatom frustules. On the other hand side I don't know what the amoeba could have used otherwise. The image was taken with the old Olympus inverted CK and a 20:1 LWD objective through the bottom of a culture bottle. So there wasn't more detail resolved.

Apparently Micrasterias are difficult to photograph perfectly. I tried to show the form of the algae by photographing a speciment that is quite inclinded, but the increasing diastance to the coverslip doesn't help the immage quality. Left upper side is the top, close to the cover slip and here the image look quite good.
It also is a problem that the surface is furry green stuff and inside are clearly formed oil drops that show too much in the stacked image.

Bob