Diatom Search #2

Here you can discuss sample and specimen preparation issues.
Post Reply
Message
Author
microb
Posts: 729
Joined: Wed Mar 27, 2019 6:39 am

Diatom Search #2

#1 Post by microb » Sun Apr 04, 2021 6:50 pm

So how you finding diatoms? I have a small pond near here and I’m not seeing them. Now the better microscopes are not assembled right now, so I’m using a light weight Nikon student one with a cheapo camera, but still looking at a reference slide I should be able to see some structures if they are there.

Procedure: Reach in pond pull out rock a foot deep and also scrap off rock at water level. Both get green particles and rock grit. Let it settle and pipette out of the mass at bottom in to a petri dish to search.

So far found a little round guy that moves around a lot. And also found some long guy that I don't know if he's doing much anymore.
Attachments
WIN_20210404_11_35_48_Pro_1K.jpg
WIN_20210404_11_35_48_Pro_1K.jpg (45.86 KiB) Viewed 2562 times
WIN_20210404_11_38_13_Pro_1K.jpg
WIN_20210404_11_38_13_Pro_1K.jpg (34 KiB) Viewed 2562 times

microb
Posts: 729
Joined: Wed Mar 27, 2019 6:39 am

Re: Diatom Search #2

#2 Post by microb » Sun Apr 04, 2021 7:24 pm

I'm trying to follow this procedure, but I don't have a river area near by. I can try an ocean area by the large rocks:

https://www.youtube.com/watch?v=Cp9ym5M0RUc

MicroBob
Posts: 3154
Joined: Sun Dec 25, 2016 9:11 am
Location: Northern Germany

Re: Diatom Search #2

#3 Post by MicroBob » Sun Apr 04, 2021 8:14 pm

Hi,
many diatoms are very small, smaller than e.g. 30µm. To see them you need a sharp image and for this a well made slide. Which microscope and objective are you using, how is your lighting set up and do you use a cover slip?

Bob

rhiannontries
Posts: 32
Joined: Wed Dec 02, 2020 5:15 am

Re: Diatom Search #2

#4 Post by rhiannontries » Sun Apr 04, 2021 9:34 pm

It is hard to tell based on the picture, but I believe the first pic is of some midge larvae. Maybe Chironomid?

microb
Posts: 729
Joined: Wed Mar 27, 2019 6:39 am

Re: Diatom Search #2

#5 Post by microb » Sun Apr 04, 2021 10:16 pm

MicroBob wrote:
Sun Apr 04, 2021 8:14 pm
Hi,
many diatoms are very small, smaller than e.g. 30µm. To see them you need a sharp image and for this a well made slide. Which microscope and objective are you using, how is your lighting set up and do you use a cover slip?

Bob
To set the scaling, here is a Klaus Kemp slide done at 4x and 10x on this NikonSE with a mercury bulb that's probably on its last leg:
Attachments
10X_1K.jpg
10X_1K.jpg (35.9 KiB) Viewed 2530 times
4X_1K.jpg
4X_1K.jpg (34.26 KiB) Viewed 2530 times

microb
Posts: 729
Joined: Wed Mar 27, 2019 6:39 am

Re: Diatom Search #2

#6 Post by microb » Sun Apr 04, 2021 10:24 pm

MicroBob wrote:
Sun Apr 04, 2021 8:14 pm
Hi,
many diatoms are very small, smaller than e.g. 30µm. To see them you need a sharp image and for this a well made slide. Which microscope and objective are you using, how is your lighting set up and do you use a cover slip?

Bob
The first were baked onto a coverslip. The second batch shown in this thread (Excluding the Klaus Kemp slide) are in a petri dish as I'm just trying to find anything at this point.

So how Kemp is using a tiny hand held by the pond to look as he collects, so I thought this cheapo Nikon that I might battery power with an LED could be used for that. Maybe I'll see if I can find a plastic hand held off Amazon. But right now, I just some algae built greenhouses and start from there.

MicroBob
Posts: 3154
Joined: Sun Dec 25, 2016 9:11 am
Location: Northern Germany

Re: Diatom Search #2

#7 Post by MicroBob » Mon Apr 05, 2021 7:44 am

The diatoms on Kemps slide are of the bigger variety. So if you wan't to find diatoms and there are only small ones you will need a better combination of magnification and image quality. For sample collecting I would suggest to make a sieve from 25-50µ stainless mesh to be able to concentrate the sample. Then just place a bit of sample and a water drop on the slide and cover it with a cover slip, adjust condenser and look for diatoms with 10:1, 20:1 or 40:1 objectives.

Post Reply