Microscopic Life

I'm on a bit of a mission to add a minimum of one new species to my yearlist every day, purely to see how long I can keep it going for before I blank. Yesterday the weather was vile, sideways rain and not at all warm. But my stupid little mission forced me out in an effort to find that 'something new' for the day. I didn't go far. About quarter of a mile north of me is a boggy area with a couple of shallow Sphagnum pools hidden amongst stands of Soft-rush. I took three empty tubes and headed out into the weather, intent on collecting a water sample. The other two tubes were back up, just in case I found something else to collect. I sloshed north, scooped some water into a pot, eyeballed a pink Sphagnum, wondered if I could ID it, and popped a bit into a second pot. Then sloshed straight back indoors again.

I thoroughly enjoy pipetting a few drops of pondwater onto a microscope slide and then systematically scanning the contents through my microscope. I have a little Apex Practitioner microscope which is actually perfectly fine for much of the time. I do need to upgrade though, maybe the Apex Scholar would be a sensible option. I'd like to start measuring some of the smaller objects and an oil immersion lens would be very handy too. Plus a binocular rather than monocular model would be a lot more comfortable to use for extended periods of time. 

At the moment I simply hold my Olympus TG-7 to the eyepiece and take images that way. I turn the focus to manual on the camera, which stops it seeking something to focus on, then use the microscope's focus wheel to bring the image sharp in the camera. The depth of field in my microscope is incredibly narrow, sometimes I need to take several images at ever so slightly different focal lengths to capture a feature on the object I'm looking at. The auto-stacking mode of the TG-7 doesn't work in this configuration, a pity really as that's precisely what I need. It's a bit of a flaky technique, and the camera is handheld which will introduce movement, but it's the best I can do at the moment. Results are decidedly mediocre, as you can see for yourself. 

First up are a few desmids for you. These photosynthesising algae achieve their greatest numbers during the long days of summer, but a few individuals can still be found even now in midwinter. Desmid diversity seems very limited in my sample, I'm not sure if that's down to the site or due to the time of year. 

Micrasterias jenneri with a chain of Tabellaria behind it

Euastrum humerosum looking like a Gummy Bear standing to attention

Xanthidium armatum looking like a WWII naval mine

Netrium digitus the tiny floating cucumber

Desmids are single-celled algae, the paler area in the centre of the paired lobes is the cell nucleus. I still find it incredible that my cheap and chirpy microscope enables me to identify such tiny organisms with a high degree of confidence. 

Another group of single-celled algae that commonly occur in Sphagnum water samples are the diatoms. The identification of the vast majority of these is beyond the capabilities of my current microscope, but I can do a handful of them. One easy to recognise group are those of the genus Tabellaria, of which just four species occur in Britain. Should be easy? No, not really. 

Tabellaria flocculosa - the 'squarish-shaped' one

Tabellaria fenestrata - the dead cell at the bottom holds the clue!

Massive crop of image above

Tabellaria form chain-like colonies. Each individual in the chain exudes a type of glue from special pores in the frustule and links itself to its neighbour by a corner. In the image we can see several individuals that are joined at the corners, the glue can be seen as a blurry smudge between individuals. Note that the bottom individual is transparent, meaning it has died, and the glue holding it to its neighbour is starting to come undone. My thought is that the glue is produced whilst the diatom is alive and presumably deteriorates if not replenished? The dead individual can be seen to comprise three long segments. The middle segment has a tiny but distinct inward kink at either end, which allows us to name the species as Tabellaria fenestrata. The only one to form square-shapes is Tabellaria flocculosa, though it does sometimes extend to more of a rectangular shape. Identifying Tabellaria quadriseptata and Tabellaria hercynica are well beyond my capabilities for now.  

There were a few rotifers in the sample (I can't do those) and many exceedingly tiny whizzy things (can't do those either) plus a good number of testate amoeba liberally scattered throughout the sample. Most of these are too small for me to pick up the kind of detail necessary to run them to genus. But some of the larger or more bizarre ones are definitely doable. Here's a selection for you to squint at.

Galeripora (Arcella) discoides yep, it looks exactly like a doughnut

Centropyxis spinosa exhibiting a smaller aperture and more curved spines than C.aculeata

Planocarina carinata munching on some hapless small things

Despite the lateral bumps, this is also Planocarina carinata!

I love watching these amoebae, though a large degree of patience is required to catch one in action. The almost transparent pseudopodia move very slowly, reaching out from within the test and oozing outwards in the search for something to digest. Judging by the amount of food items visible inside many of the tests, they are highly efficient hunters. Or maybe they just take a very long time to digest anything.  

Very occasionally a 'huge' copepod will flash through the field of view, a startling thing indeed after an hour of slowly panning around a field of essentially stationary objects. What I don't find very often are tardigrades, possibly a good thing because I'm not able to identify them to species, but they're fun to watch as they slowly swim nowhere. 

 Hyalotheca dissiliens encased in a near transparent tube of thick mucilage

I still have plenty of water left in the tube, doubtless I'll pop a few more drops beneath the microscope over the next day or so. The pink Sphagnum that I grabbed as an afterthought turned out to be Sphagnum rubellum, determined by the shape and length of the stem leaves and microscopically by the elongated and tightly packed cells in the basal corners of the stem leaves. It's been fairly recently split out as a full species after having previously been known as a form of S.capillifolium. Nick Hodgetts showed me capillifolium a few years back (he wrote the Sphagnum book, I take his word when he tells me what Sphagnum I'm looking at!) but Sphagnum rubellum itself is a lifer for me. 

So, a rainy day and a fifteen minute escapade into it has given me quite a few new species for my yearlist and, most surprisingly, four lifers for my PSL! Happy days indeed.