River diatoms and "bubbles"
River diatoms and "bubbles"
Hi All,
Health and safety to everyone.
A week before the corona lock-down I collected a live diatom sample from a small polluted local river. As expected, most diatoms were pennales and the variability was poor. Nevertheless, I cleaned them with APS* and home-grade hypochlorite, and managed to prepare a few Pleurax strew slides. In spite of my sloppy preparation and plenty of debris, diatoms could be clearly observed. I inspected them with the following objectives : 40X/0.75 phase contrast (PC) dry, 40X/0.8 (iris) oil darkfield (DF), 100X/1.3 Planapo PC (oil), 100X/1.25 achromat (oil) sort-of-DF. The ultracondenser (oil) was used for DF. Images were taken with the afocally-installed mirrorless, except for DF which were taken with an eyepiece camera.
I always start a diatom session by phase contrast; at 40X or 100X PC it is fun (see photo 1 for an example), and well worth the trouble of the oil immersion. Diatom lengths were mostly 15-50 um. Due to the gentle cleaning, many diatoms remained fairly intact (photos 2 & 3), although some were broken into valves and girdles. Diatoms that appear much brighter and more colorful than others are, I believe, intact frustules. Others might be just valves. Photo 2 shows two diatoms (Naviculas?), that are mutually aligned, perhaps owing to the shape of their outer surfaces, or maybe they are actually a single "thick" frustule ??
I noticed a circle, an air bubble - what else could it be? (Photo 4, PC). Then another circle appeared (photo 5, DF), and another. Strangely enough, they are all about the same diameter - 15-20 um. Such uniform air bubbles?. Switched the slide for another and tried BF with the 40X dry (photo 6, middle). Now that is not a bubble, but a short transparent open tube. Tried oblique (photo 7) - it is a transparent shallow cylindrical container. And the same conclusion from another (photo 8, BF). Later, I found one that was lying on its side (photo 9, DF). And, just very few so far, I found the valve (perhaps still part of the intact frustule) of Cyclotella meneghiniana Kutzing**.
* APS cleaning is less hazardous than many literature procedures, but appropriate precautions and laboratory safety measures are mandatory.
** Identification is based on an atlas of local diatoms.
So, several illumination modes can help to answer a question.
Comments are welcome.
Health and safety to everyone.
A week before the corona lock-down I collected a live diatom sample from a small polluted local river. As expected, most diatoms were pennales and the variability was poor. Nevertheless, I cleaned them with APS* and home-grade hypochlorite, and managed to prepare a few Pleurax strew slides. In spite of my sloppy preparation and plenty of debris, diatoms could be clearly observed. I inspected them with the following objectives : 40X/0.75 phase contrast (PC) dry, 40X/0.8 (iris) oil darkfield (DF), 100X/1.3 Planapo PC (oil), 100X/1.25 achromat (oil) sort-of-DF. The ultracondenser (oil) was used for DF. Images were taken with the afocally-installed mirrorless, except for DF which were taken with an eyepiece camera.
I always start a diatom session by phase contrast; at 40X or 100X PC it is fun (see photo 1 for an example), and well worth the trouble of the oil immersion. Diatom lengths were mostly 15-50 um. Due to the gentle cleaning, many diatoms remained fairly intact (photos 2 & 3), although some were broken into valves and girdles. Diatoms that appear much brighter and more colorful than others are, I believe, intact frustules. Others might be just valves. Photo 2 shows two diatoms (Naviculas?), that are mutually aligned, perhaps owing to the shape of their outer surfaces, or maybe they are actually a single "thick" frustule ??
I noticed a circle, an air bubble - what else could it be? (Photo 4, PC). Then another circle appeared (photo 5, DF), and another. Strangely enough, they are all about the same diameter - 15-20 um. Such uniform air bubbles?. Switched the slide for another and tried BF with the 40X dry (photo 6, middle). Now that is not a bubble, but a short transparent open tube. Tried oblique (photo 7) - it is a transparent shallow cylindrical container. And the same conclusion from another (photo 8, BF). Later, I found one that was lying on its side (photo 9, DF). And, just very few so far, I found the valve (perhaps still part of the intact frustule) of Cyclotella meneghiniana Kutzing**.
* APS cleaning is less hazardous than many literature procedures, but appropriate precautions and laboratory safety measures are mandatory.
** Identification is based on an atlas of local diatoms.
So, several illumination modes can help to answer a question.
Comments are welcome.
- Attachments
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- (1) 100X PC.jpg (92.47 KiB) Viewed 6173 times
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- (2) Two separate diatoms or one. Stack of 5. 100X PC. Cropped.jpg (56.61 KiB) Viewed 6173 times
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- (3) Surirella ovalis Brebisson. STack of 5. 100X PC. Cropped.jpg (22.57 KiB) Viewed 6173 times
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- (4) Suspected air bubble -or else. 100X PC.JPG (57.45 KiB) Viewed 6173 times
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- (5) Suspected air bubble - or else. 100X DF.jpg (44.47 KiB) Viewed 6173 times
Last edited by Hobbyst46 on Fri Apr 10, 2020 11:04 pm, edited 1 time in total.
Re: River diatoms and "bubbles"
(continued)
- Attachments
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- (6) Suspected circle. 40X BF.JPG (59.6 KiB) Viewed 6172 times
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- (7) Cylindrical transparent container. 40X oblique.JPG (59.62 KiB) Viewed 6172 times
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- (8) Cylindrical transparent container. 40X BF.JPG (60.84 KiB) Viewed 6172 times
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- (9) Cylindrical transparent container on its side. 100X DF. Cropped.jpg (10.42 KiB) Viewed 6172 times
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- (10) Cyclotella meneghiniana Kutzing. 100X PC.JPG (57.49 KiB) Viewed 6172 times
Re: River diatoms and "bubbles"
Excellent ... Congratulations !!Later, I found one that was lying on its side (photo 9, DF)
MichaelG.
Too many 'projects'
Re: River diatoms and "bubbles"
Hi Doron,
nice catch!
Could these cylinders be the girdle bands of centrales diatoms? So valves and circular objects match in numbers so this could be true?
Bob
nice catch!
Could these cylinders be the girdle bands of centrales diatoms? So valves and circular objects match in numbers so this could be true?
Bob
Re: River diatoms and "bubbles"
Thanks, MichaelG and MicroBob!
Bob, I indeed believe that the cylinders are top-valve-less Cyclotella frustules. So photo 9 is a girdle view and photo 10 is the top valve view. Possibly, the cleaning procedure, gentle as it was, removed the top valve from the frustule. Statistically, there should have been the same number of girdles as valves, but I do not have enough evidence for this, because the corona lock-down is preventing me from making more slides. In the existing 2-3 slides, I only found one Cyclotella valve and very few valve-less frustules.
Cyclotella are incredibly complex structures, as seen by SEM. A short literature survey showed me that there are many descriptions of the valves, but very few girdle views.
Bob, I indeed believe that the cylinders are top-valve-less Cyclotella frustules. So photo 9 is a girdle view and photo 10 is the top valve view. Possibly, the cleaning procedure, gentle as it was, removed the top valve from the frustule. Statistically, there should have been the same number of girdles as valves, but I do not have enough evidence for this, because the corona lock-down is preventing me from making more slides. In the existing 2-3 slides, I only found one Cyclotella valve and very few valve-less frustules.
Cyclotella are incredibly complex structures, as seen by SEM. A short literature survey showed me that there are many descriptions of the valves, but very few girdle views.
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Re: River diatoms and "bubbles"
I'm awe inspired.
Re: River diatoms and "bubbles"
One of these days I am going to get around to making a strew slide.
Only thing stopping me is the amount of work involved. ;)
Nice work!
Only thing stopping me is the amount of work involved. ;)
Nice work!
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)
Olympus E-P2 (Micro Four Thirds Camera)
Re: River diatoms and "bubbles"
Many thanks 75RR.
Re: River diatoms and "bubbles"
Most definitely
https://www.sciencephoto.com/media/8745 ... diatom-sem
https://naturalhistory2.si.edu/smsfp/ir ... hryso1.htm
What worries me a little, though, is that they generally seem to be much lower-profile than what you show
I am quite ignorant of these things, so ... can anyone nominate a species with the 'Hobbyst46' aspect-ratio ?
MichaelG.
Too many 'projects'
Re: River diatoms and "bubbles"
Thanks for the comment, Michael!
In the Atlas there were only valve views, but as Fortuna struck I just found this beautiful source:
Nordic Microalgae
http://nordicmicroalgae.org/taxon/Cyclo ... neghiniana
They provide rich data and a table that gives sizes and aspect ratios. It appears that "my" aspect ratio" of ~0.83 is OK for this species.
Apparently the aspect ratio varies from species to species. Good to know!
Re: River diatoms and "bubbles"
Brilliant find ... Thank YouHobbyst46 wrote: ↑Sat Apr 11, 2020 3:58 pmI just found this beautiful source:
Nordic Microalgae
http://nordicmicroalgae.org/taxon/Cyclo ... neghiniana
They provide rich data and a table that gives sizes and aspect ratios. It appears that "my" aspect ratio" of ~0.83 is OK for this species.
Apparently the aspect ratio varies from species to species. Good to know!
MichaelG.
Too many 'projects'
Re: River diatoms and "bubbles"
Thanks DonShcaeffer !
Re: River diatoms and "bubbles"
Could not resist adding another diatom, Nitzschia, which I managed to identify.
- Attachments
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- (11) Nitzschia sigma. Stack of 4. 100X PC. Cropped.jpg (33.62 KiB) Viewed 6031 times
Re: River diatoms and "bubbles"
Thanks daruosha!
Re: River diatoms and "bubbles"
That is a nice image of a Nitzschia
Have you tried to image diatoms using COL?
Would be nice to see a same subject comparison with Phase/COL
Have you tried to image diatoms using COL?
Would be nice to see a same subject comparison with Phase/COL
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)
Olympus E-P2 (Micro Four Thirds Camera)
Re: River diatoms and "bubbles"
Tried it with three different diatoms. Could not find my original nice Nitzschia (forgot to document the location on the slide... ) so
here are others, two Naviculas and a different Nitzschia. Identifications are tentative, might be wrong.
All were imaged with the 100X1.3 oil Ph3 objective. Oblique was done by displacing the condenser from the phase 3 position.
All photos are single images.
Phase contrast images were slightly brightened in post-p, then resized and cropped.
Oblique images were brightened, contrast was enhanced, then resized and cropped 9all crops by ~2X in each direction).
- Attachments
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- Navicula geoppertina (32um) phase contrast.jpg (74.35 KiB) Viewed 5937 times
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- Navicula geoppertina oblique.jpg (77.22 KiB) Viewed 5937 times
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- Navicula recens (48um) phase contrast.jpg (74.4 KiB) Viewed 5937 times
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- Navicula recens oblique.jpg (105.86 KiB) Viewed 5937 times
Re: River diatoms and "bubbles"
Continued.
note: the transparent "square" form near the bottom end of the Nitzschia is a frustule of Cyclotella (minus a valve), lying on its side, as described in the post above.
note: the transparent "square" form near the bottom end of the Nitzschia is a frustule of Cyclotella (minus a valve), lying on its side, as described in the post above.
- Attachments
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- Nitzschia sp. (82um) phase contrast.JPG (69.31 KiB) Viewed 5934 times
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- Nitzschia obliqu.JPG (112.33 KiB) Viewed 5934 times
Re: River diatoms and "bubbles"
Amazing stuff. Thanks for posting, in fact this got me inspired to go the local canal and take a bit of brown scum which was chock full of diatoms.
Zeiss Photomicroscope III BF/DF/Pol/Ph/DIC/FL/Jamin-Lebedeff
Youtube channel
Youtube channel