MicrobeHunter.com Microscopy Forum

75RR (Glen) sent me some seaweed and sand samples from the shores of Southern Spain in the Mediterranean, around the Alboran sea. Here are some pictures of the sample after cleaning and sorting through about 50 strew slides to a keeper slide. Taken through a B&L SZ7 and Canon EOS:
Left half of diatoms with 1X setting on the SZ7 Right half Close up of the different diatoms starting from the left at 7X setting on the SZ7

Some unusual (to me) diatoms

Nice variety! - including a few I have not come across myself.

Thinking of following your example ...

When you mentioned that you 'swirl the water and then decant', is that by hand or with a centrifuge?

I put the samples in a jar of water, swirl vigorously by hand and decant immediately to a second jar. I add more water to the sample jar again repeat until the swirled water is clear. Then I let the second jar settle for 24 hours, decant the top third of the water, add more water and decant again after 12-24 hrs until the salt water is gone. After the salt is gone, I decant as much water off and add about 100 ml of HCl and let it set for a week. After a week, I decant the HCl off and put in fresh HCl for another week. Then I decant the HCl and add about 100 ml of H2SO4 and let set for a day. I then rinse with Distilled water, let set and decant at least 6 times until all the acid is gone. I try to remove any large particles of sand by swirling and decanting the top off. I then make strew slides of 12-15 drops on a slide warmed over a warmer. Then I pick off the diatoms to a keeper slide.

Of course you don't need to do the cleaning with the acids, but the sample will be full of organics and other minerals.

Fantastic diversity.
From which depth (in the mud, and below the water) was the sand collected ?
It is great that you do not boil in acid any more.

Hobbyst46 wrote: ↑

Sat Apr 03, 2021 3:02 pm

Fantastic diversity.
From which depth (in the mud, and below the water) was the sand collected ?
It is great that you do not boil in acid any more.

I still acid treat, but just let the sample set in it and not boiled. See the edit above.

Hobbyst46 wrote: ↑

Sat Apr 03, 2021 3:02 pm

Fantastic diversity.
From which depth (in the mud, and below the water) was the sand collected ?

I used a jam jar to scoop the wet sand from the surface down to 2 - 3 cm at low water.

You might find this link useful. You can set it for your area

https://www.tidetime.org/europe/spain/estepona.htm

75RR wrote: ↑

Sat Apr 03, 2021 4:16 pm

Hobbyst46 wrote: ↑

Sat Apr 03, 2021 3:02 pm

Fantastic diversity.
From which depth (in the mud, and below the water) was the sand collected ?

I used a jam jar to scoop the wet sand from the surface down to 2 - 3 cm at low water.

You might find this link useful. You can set it for your area

https://www.tidetime.org/europe/spain/estepona.htm

Thanks 75RR. Local tide is just 10cm...

Jealous of your international sample! So many interesting and different species in there, and nicely showcased on the slide!

ScienceMatters wrote: ↑

Sat Apr 03, 2021 6:07 pm

Jealous of your international sample! So many interesting and different species in there, and nicely showcased on the slide!

You will be surprised at the variety of different species from any location. Most locations will get you 25-40 species. The trick is:
- Getting a variety of samples...sand, plants growing in the water, rocks, or things in the water.
- A good quantity of the samples.
- Concentrating the diatoms
- Being able to manipulate from strew to a keeper slide to permanent slide, which shows you your different species.

You can see the variety I was getting locally from different locations as well as from other US locations in this post:
https://www.microbehunter.com/microscop ... =10&t=4227

Charles wrote: ↑

Sat Apr 03, 2021 9:53 pm

You can see the variety I was getting locally from different locations as well as from other US locations in this post:
https://www.microbehunter.com/microscop ... =10&t=4227

Very interesting to read about your techniques and see the results. Without these methods I’d say I normally only see 8-10 species per slide.

I tried to make a test permanent side from this sample. I wanted to make a test slide because diatoms react different ways depending on their shape and side. I was trying to see if they would shift during the mounting process. I figured the most likely ones which would shift are the large ones like the Biddlulphia.

I cleaned a coverslip, applied some adhesive and put six samples of Biddulphia in different orientations, front, back, side, girdle attached and full frustule. I set the adhesive. Then I applied a drop of Zrax mountant and gently heated it and labelled it. And this is what I see. Like a bomb went off and crushed all the frustules. Now I'll see how I'm going to add some spacers to protect the diatoms.

Would be interested to learn where you sourced the spacer discs please.

Best, deBult

Charles, I tried punching the spacers from an aluminum foil (as per your post), but it did not work for me.
MicroBob has suggested flat stainless shim rings. I bought some, 18x12x0.1 mm, to try. More for dry mounts, but maybe it will work with Pleurax as well.

deBult wrote: ↑

Sun May 09, 2021 3:34 am

Would be interested to learn where you sourced the spacer discs please.

I take a hyperdermic need which has the beveled end clipped straight across and poke it into thin aluminum foil or disposable pie plates. You can see the description here: https://www.microbehunter.com/microscop ... &start=150

Hobbyst46 wrote: ↑

Sun May 09, 2021 6:45 am

Charles, I tried punching the spacers from an aluminum foil (as per your post), but it did not work for me.
MicroBob has suggested flat stainless shim rings. I bought some, 18x12x0.1 mm, to try. More for dry mounts, but maybe it will work with Pleurax as well.

The only problem I see with rings are that when heated the mountant fumes need to escape from under the cover slip to the edges. The rings could prevent that and lift the slip up?

Charles wrote: ↑

Sun May 09, 2021 4:03 pm

Hobbyst46 wrote: ↑

Sun May 09, 2021 6:45 am

Charles, I tried punching the spacers from an aluminum foil (as per your post), but it did not work for me.
MicroBob has suggested flat stainless shim rings. I bought some, 18x12x0.1 mm, to try. More for dry mounts, but maybe it will work with Pleurax as well.

The only problem I see with rings are that when heated the mountant fumes need to escape from under the cover slip to the edges. The rings could prevent that and lift the slip up?

Yes, likely. Will have to glue the ring with gelatin (or, better, PAM) first.

Test 2. I decided to try just adding a bit more mountant. Came out a little better but still some breakage, but it may have happened because the coverslip wasn't sitting right and I had to move it a couple mm. May also be the reason one of the Biddulphia moved. Taken with B&L SZ7 at 7 setting and Canon EOS.

Nice ... seems you are almost there - then again the Biddulphia have got to be some of the most challenging to mount!