Bruce Taylor

Difficulty identifying algae in pond water samples

I thought I would use the holiday period as a time to identify the algal organisms in the stream water samples in my previous post (from the stream next to the heritage canal in Lichfield).

…….and have discovered how difficult this is!

Quite simply – the features discussed in the books are not easy to identify in the photos I took. Therefore, I need to look down the microscope at samples taken to specifically look for features like cilia and organelles.

Andy

The following pictures show photos of organisms I was hoping to identify together with exemplar pages from identification manuals.

 

Below is a picture of one particular organism I have been trying to identify (green ball upper left of image) and below that several possibilities I think it might be:

The same organism is shown blown up further below in bright field and dark field:

 

Looking at the blown up photo, it looks like this organism is a multicellular green organism with around 60 or so cells. Organelles are clearly present.

i can not see cilia or flagella but that does not mean that they are not present.

Based on this, it seems to me that Eurodina or Volvox are possibilities for the identification of this organism, although note that below that Bruce feels it is more likely to be Volvox. I have pasted links to Volvox videos on YouTube at bottom of this post – those videos are not mine.

in any case, it looks like this organism is part of the following class – and may be in practice identifying the class of organisms might be the best I can hope to achieve for a while, until I get more experience.

Andy

 

 On 29 May 2017, at 10:07, Andrew Thornett wrote to Bruce Taylor:

Hi Bruce,

Thanks for you help in the past with my explorations in microscopy.
I have posted my researches at http://roslistonastronomy.uk/category/microscopy
I have been trying to identify some of the organisms I am looking at – I think I might be missing a basic part of the approach. Would you be able to guide me on how to approach identification.
See for example the issues I am having:
http://roslistonastronomy.uk/difficulty-identifying-algae-in-pond-water-samples
Andy
From: Bruce Taylor (www.itcamefromthepond.com):
Date: 29/05/2017 13:05
To: Andrew Thornett
Subject: Identifying pond organisms

Hi Andrew,

The difficulties you’re having with identification are quite normal. It will certainly become easier as you acquire experience, but there will always find some things in your microscope that resist explanation! Increasing magnification and image resolution will help. Some of your images are in darkfield, or partial darkfield, which is not very good for identification (except for a few very specialized applications, like spotting spirochetes in human blood!). For instance, I wouldn’t even attempt to identify the filaments in the second image (experience suggests unhealthy remnants of a filamentous green alga, but without a glimpse of the chloroplasts even that is in doubt).

In the brightfield images, I see a few empty diatom frustules in the brightfield images. The ones that look like bent canoes are cymbelloid diatoms (possessing asymmetrical frustules, like those of Cymbella). there are lots of sites that offer help with diatom identification (this one, for instance: http://westerndiatoms.colorado.edu/ ).  I don’t pay much attention to them, as a group, but the procedures for identifying organisms are the same for all groups. You need to learn the basic anatomical features that set one taxon apart from the other. Does your diatom have a “raphe” (central line down the middle)? What kind of “striae” (perpendicular or oblique striations) does it have? And so on.

As for the green ball, it appears to be a small colonial volvocid in a gelatinous envelope, such as Pandorina morum. However, we don’t see a lot of detail, so I wouldn’t necessarily try to give it a genus, let alone species. A general, high-level identification should be satisfactory. I’d simply call it a “volvocid alga, possibly Pandorina.”

I hope this helps, a bit!

cheers,

Bruce
Hi Bruce,
Another thing that I find somewhat confusing is that the books should two views of each organism looking down (valvular view) and what looks like looking across the structure. One of the organisms in my photos on link below shows square structure and I am guessing this is crossways view as it does not appear to be the same as anything in books you kindly sent me. But I can’t tell which one!
Also my reading suggests these organisms have different looks when as spores or mature organisms but I don’t know what difference in view between two is…..
Andy
From: Thornett Andrew
Sent: Monday, May 29, 2017 03:16
To: Bruce Taylor
Subject: Re: Identifying pond organismsIt does indeed – thank you very much.
“empty diatom frustules” – that explains why I could not work those out – I thought it was weird that they were only simple square objects without anything obvious inside them! Why would they be empty? Are they the remnants of dead organisms or is this part of the division process?
Andy
From: Bruce Taylor
Sent: 29 May 2017 16:12
To: Thornett Andrew
Subject: Re: Identifying pond organismsYes, these are just the shells of dead organisms. Diatom shells are made of silica (like glass), and are very durable. When the organism dies, the living part of the diatom is consumed by bacteria or other protists, and the shell sinks down into the muck at the bottom of the water. They can pile up down there and form large deposits of “diatomaceous earth,” which can endure for millions of years.If most of the diatoms are dead, it is usually a sign that your sample is old, or that it was taken at a time of year when algae are mostly dormant.best,
Bruce

Videos of Volvox from YouTube (not my own) to compare with pictures above – do you think my picture is of Volvox?

https://www.youtube.com/watch?v=He9FSeGRi3A

 

 

Identifying Protozoa in Andrew’s post 15/4/2017

From: Bruce Taylor (www.itcamefromthepond.com)
Sent: 16 April 2017 01:23
To: Thornett Andrew (05Y) Walsall CCG
Subject: Re: FW: Identifying Protozoa and algae

Hi Andy,

Nice site…and nice microscope!

The first and second videos at the top of the page are both Spirostomum, a ciliated protozoan. The specimen appears to have a single, centrally located “macronucleus” (the larger of the 2 types of ciliate cell nucleus), so it is probably Spirostomum teres.

The 8th video is another ciliate, of the genus Frontonia. It might be F. angusta, but we’d need a closer look to be sure.

The 3rd video is a pennate diatom. Videos 5,6,7, 9 and 10 are also diatoms, of different species. I’ll add a little identification guide to the shared DropBox folder I started (you should have received an invitation, by now). There are lots of websites that help with diatom identification. Here is one (it focuses on American diatoms, but most are cosmopolitan): https://westerndiatoms.colorado.edu/

The 4th video is a filamentous green algae (family Zygmataceae). I have some algae texts on hand, and can place a couple of them in the DropBox folder, if you like.

In the still images, I see lots more diatoms, and at least one peritrich ciliate (an epistylid, most likely).

If you have specific questions, please feel free to ask.

best,

Bruce

Microscopic observation of larva in pond water 5/2/2017

Biggest predator to date that I have found!

Andy

From: Bruce Taylor (www.itcamefromthepond.com)

What is this? An insect larva, certainly. We don’t see the head, unfortunately, but those little claws at the tail end might suggest a chironomid larva (midge). Like this guy: https://www.youtube.com/watch?v=WMWFJU4HkUQ

Bruce

Bucket water under Zeiss IM microscope – brightfield and phase contrast

Bucket water 400x 050217(I)

Video from today’s session can be found on YouTube at https://youtu.be/A1JsKR4DUp0

I am learning a lot about my new instrument. In particular, I am getting to grips with which bit is which. I now realise that I have one phase contrast objective at present – 10x (giving 100x magnification). The others are not phase but there is still an interesting effect if I use them with phase ring which darkens background – although I suspect they are not supposed to be used that way!

This really is an exciting and fun thing to do – and I recommend that anyone else with an interest look out for an old Zeiss or Leica lab microscope – it will blow your mind!

It is also invigorating – giving me that night time excitement I get at the telescope even when it is in the day and the Sun is not shining so I can’t use the solar scope.

Anyway, our next door neighbour built a new garage 2-3 years ago and alongside the garage in a dead area is a bucket which filled with rain-water that I thought must have matured by now…..so I thought I would take a look and see what I could find in it!

I put 2-3 pipettes of the bucket water into a Petri dish and slipped in under the microscope without staining – all photos here were from views of that sample.

From Bruce Taylor (www.itcamefromthepond.com)

What are they? They’re heterotrophic flagellates, but I’m having a hard time seeing useful identifying features. Flagella are briefly visible in one specimen, at 1:57, and there’s another specimen at the same time that resembles Chilomonas (it’s not clear whether that individual is of the same species as the others).  They might also be heterotrophic euglenids of some kind (Astasia, Khawkinea, etc)…hard to say!

I’m far more comfortable with ciliate identifications, but if you can clearer footage of these guys I’ll see if I can help.

Bruce

Taking a sample of bucket water:

20170205_093606

40x magnification, brightfield view:

Bucket water 40x 050217(I)

There are multiple small organisms swimming around here – not obvious in the still but easier to see in the video or at higher magnification. Lot of algae as you would expect, which at higher powers is clearly the foodstuffs for these swimmers.

100x magnification, brightfield.

Bucket water 100x 050217(I)

Now in middle horizontally, 25% from top is one of the swimmers. Another is slightly curved as it turns to the right 30% from right just below the first vertically.

200x magnification, brightfield:

Bucket water 200x 050217(I).

Now one of the swimmers is enlarged 40% from right, 15% from top. Algae more obvious.

400x magnification, brightfield:

Bucket water 400x 050217(I)

A much better picture showing a group of the swimming organisms feeding on a piece of algae. Note that internal structure is now quite detailed with obvious gut and other rounded structures present.

Phase contrast views:

I have only one phase contrast objective – one of my 10x. The following three photographs are all using this objective – in order: brightfield, Phase I ring, Phase II ring – I am not sure which ring is considered by Zeiss to be correct one for my lens, if any of them are! Good news is that the phase plate seems quite simple so I am hoping I can make others if I need to, to suit other phase objectives, if and when I get some.

Bucket water 100x Phase objective brightfield 050217(I) Bucket water 100x Phase objective phase plate I 050217(I) Bucket water 100x Phase objective phase plate II 050217(I)

In my view, Phase plate I highlighted the swimming organisms structure the best and did bring out information not easily seen in bright field. I did not think Phase plate II was particularly helpful with this lens.

Andy