Springtime: A Peek in the Pond

[WalterD]

This time I've been checking out a small pond isolated from other waters. Of course there are many similar ones in this area, conditions not as specifics as fens, e.g. regarding pH and nutrients levels.
As the amount of daylight increases rapidly day by day, the past 2 weeks an explosion of algae growth could be seen. Filamentous, one cell thin algae forming a slimy green substance floating on top of the water. (picture not included in this post, not Spirogyra though).
Life int his water is so abundant that you could leave your planktonnet at home, anyhow that's what I did albeit more for practical reasons. Filling one or two sample bottles by slowly flooding them with water from the “green slime”, adding a tiny piece of vegetation and there will be enough to discover for days.
Under the lens it was again crowded as can be, partially with cyclops, water fleas and rotifers pictured in previous posts. Besides that I found Scapholeberis mucronata (a water flea),a 2mm long beetle (a water beetle or one that fell into the water? Its legs don't show any adjustment for swimming ), red water mites (Hydrachna) small rotifers, among other species that I could not identify and were just too fast to capture.

Another interesting thing was microscopical algae growth on a small leaf, in greenish ball shaped units almost as small as the tip of a needle. Filaments also only one cell thick,not sure whether this type will remain small or this is the “birth” of the algae as described above.

Edit 25/03: Corrections:
-Water beetle >read: possibly an aquatic insect of the Heteroptera suborder.
-Filamentous Algae > read: Chaetophora Elegans
-Scapholeberis >read: Daphnia Longispina




1. Filamentous Algae 10x/0.30



2. Water flea (Scapholeberis mucronata) 6.3x darkfield


3. Ditto 32x/0.70 “pseudo” DIC (Imagine what a water flea would look like when not transparant.)


4. Red water mite 6.3x




5. Rotifer 40x/0.65 DIC (stacked from 3 images)



6. (Water?) beetle 9x/0.20 reflected light.



Double resolution Download-link :
https://we.tl/FDFzoWoyhM



Thanks for looking.

[GaryB]

Another gorgeous set, well done!

[Ecki]

Very nice!

[CEN]

Superb set!!!

Just one remark: Are you sure that image 2 and 3 show Scapholeberis mucronata? For me it looks more like Daphnia longispina than Scapholeberis.

Edit: Another remark: The "water beetle" does not look like a beetle (Coleoptera). It might be a member of Mesoveliidae (Heteroptera).

Regards

Christian

[carlos.uruguay]

Super!

[Johann]

Very nice!

[zzffnn]

Very nice! Thank you for sharing!

[Jacek]

Very nice

[curt0909]

Great images. I especially like the water flea

[actinophrys]

I agree with CEN, the water flea is a Daphnia – the front margin is curved and the tail spine is at the back, whereas in Scapholeberis the front margin is straight and extends directly into the spines. You can also see carapace markings in a diagonal grid rather than as lengthwise lines.

The ball of algae is Chaetophora, though I think research has suggested some species should be reclassified. And while I'm at it, the rotifer is likely Pompholyx, though I'm not certain; those for instance typically have two eyes which aren't visible here.

[WalterD]

Glad you like it!,
CEN and actinophrys: many thanks for the excellent feedback regarding ID's. Was focussed on "golden algae" in "Das Leben im Wassertropfen", now understand this should be Chaetophora Elegans. Interesting to hear its scientific classification might be changed. The waterflea was indeed Daphnia Longispina which looks like the much larger Daphnia Pulex, was distracted by its front view.
Regarding the rotifer Pompholyx: I've seen other images and it's a cute rotifer indeed. However the one portrayed here has got one eye, basically on the other side behind the " mouth", realtively much larger compared to its body length than that Pompholyx. That also counts for its ciliates. Are these relative sizes relevant for determination?

Some additional images of the Chaetophora, mouth parts of the water mite and a different rotifer. Do you know why its front end is equipped with knife-like shields? (I don't)
(it turned out to be effective when that rotifer was being bullied by what looked like an even smaller copepod larvae. It attacked the little rascal and was not bothered after)

7. Water mite, mouth parts and legs details 16x/0.45 brightfield



8. Chaetophora Elegans 10x/0.30 brightfield,stitched from 4 stacks.



9. Chaetophora Elegans 6.3x/0.20 darkfield



10. Chaetophora Elegans 16x/0.45 darkfield




11. Rotifer (to be further identified) DIC 40x/0.65

[actinophrys]

However the one portrayed here has got one eye, basically on the other side behind the " mouth", realtively much larger compared to its body length than that Pompholyx. That also counts for its ciliates. Are these relative sizes relevant for determination?

It's hard to say; rotifer genera are often defined by features like mastax and lorica details, but without those all sorts of things might be handy in recognizing them. If it only had one eye, I think it could be Anuraeopsis, which do have longer tufts of cilia on the sides. The key character is that the lorica is split down the sides, and its front is often lobed, which were not plain to me here.

I can do better for your second rotifer, which is definitely a Notholca. If you are using Streble & Krauter, note their Argonotholca is also now generally included in this same genus. The spikes on the front are presumably for just the sort of thing you saw, making them more difficult to eat. In at least some Keratella and Brachionus they are actually induced defenses – the rotifers grow additional or longer spines when more predators occur in their habitat.

[WalterD]

Actinophrys, thanks for the interesting explanation and identifying the latest rotifer.

Cheers,

Walter

[sushidelic]

A joy to look at - thanks for sharing!

[Marek Mis]

Perfect quality and very beautiful images ! DIC water flea and Chaetophora are ready to hang them on the wall

Marek