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MY FAVOURITE PLANT COMMUNITY - SPHAGNETUM

by Keith Brocklehurst

[Balsam Post Issue 61 (October 2003) page 42.]


A microscopist in bogland or fenland - it doesn’t sound too attractive. Bog or fen communities dominated by species of the genus Sphagnum, are somewhat featureless in overall view, and particularly so if walking the Pennine Way in cloud! But wait a minute; the wonderful living microcosm in Sphagnetum is not readily visible, so don’t dismiss wetland bogs and fens without even sampling them microscopically. Biologically they provide as good samples of all the major groups of Protozoa and Algae and of many groups of invertebrates as can be found anywhere.

Collection requires only bags, bottles, a small funnel and a jug, all in plastic. Furthermore, with some attention to making enrichment cultures and selective subcultures (see B.P.No.23, p.28) one can avoid vast amounts of searching time in the lab. A d.i.y. braking micropipette which overcomes problems of capillarity (see B.P.No.26, p31), will fine-hone your selection techniques under a stereomicroscope, and improve your temporary mounts of live specimens. This simple piece of glassware allows you to reduce or even eliminate the ‘organic clutter’ which so often spoils live fresh-water images and their recordings, and it does not break the bank!

There is nothing as economical and convenient as a vaseline-supported mount of live micro-specimens. Dispensed from a 5ml. syringe (without needle), vaseline supports at corners or on opposite sides of square covers can be quickly and neatly made. Three such mounts containing specimens micro-pipetted from cultures which have been left undisturbed recently can provide a full evening’s entertainment and satisfying recordings. There are more sophisticated and expensive containers suitable for more extended viewing such as the Camlab microslides, which are optically flat and precise rectangular glass tubes. They are obtainable in several sizes; initially try to borrow or beg one with a 0.4 mm.deep gap between top and bottom glass wall of the tube. A braking micropipette is ideal for loading specimens into these tubes; it can also be used to replenish evaporation losses with distilled water. I always think ‘microslide’ is a misleading name for these useful items of microscopical glassware. Perhaps this is because they were first produced commercially in Russia. Cruickshank chambers, an even more sophisticated accessory designed originally for tissue culture work and perhaps not so well known or as generally useful as microslides, used to be machined from 0.25”perspex sheet.. They have appeared at our PMS meetings, and are now available ready made; but they are expensive. However, with several grades of square coverglass and some Canada balsam one can easily and cheaply make a set of support slides with depths ideal for your particular specimens. A compressorium or even a Sedgewick-Rafter slide can also be valuable in this work. So much for a little introductory technique which might promote success and even joy in looking at Sphagnum and the living creatures it contains.

You may already know the excellent Microscopic Life in Sphagnum by Marjorie Hingley, the attractive Naturalists’ Handbook No.20 in the Richmond Publishing Company’s Series. In this 64 page booklet the author has included a remarkable amount of information about the organisms closely associated with Sphagnum, a general identification key, and also seven supplementary keys / guides, lots of illustrations and a useful bibliography I was interested to read in Marjorie Hingley’s acknowledgements that she was inspired by Sarah Corbet’s paper on Testate Rhizopods of the Malham Tarn Area. I am pleased to admit that the same applied to me. Sarah Corbet wrote the paper originally in order to give a party of undergraduates something to do during a stay at Malham Tarn Field Centre; it was first published in Field Studies Vol 3, No. 5 1973. Visitors to the Field Centre may have used its illustrations and keys which provide a really helpful introduction to this little understood group of protozoa.

In this article I am hoping the images which follow will support my views of Sphagnetum, and induce at least some readers to put their wellies in the car boot next time they are visiting bogland areas or fens. Most of the images were made with phase-contrast optics.





1. Actinosphaerium eichhorni Fascinating to watch live; has fed on Micrasterias rotata.
A free-swimming Stentor settled nearby. Body 250Ám dia.



2. Actinophrys sol Another Heliozoan, often with zoochlorellae. Body ca. 40 Ám.



3. Acanthocystis sp. Spines said to be siliceous, visibly bifurcate at ends.



4. Micrasterias rotata. Beautiful, a photographer’s favourite. Can be seen by naked eye. The desmid genus everyone recognizes.



5. Closterium sp. Only half shown. Terminal vacuoles with moving crystals of calcium sulphate fascinate. Chloroplast with long ridges, circles are pyrenoids, superb alga for observing cytoplasmic streaming. A video capture.



6 .Amoeba proteus Up to 400 Ám long when active, longitudinal ridges granular nucleus, ‘wrinkled’ uroid, granular nucleus For more see P.M.S. web site.



7. Amoeba proteus in fission a few secs. before separation.



8. Mayorella bigemma the web-footed amoeba. Vesicular nucleus. Identifiable by bright hour-glass shaped bodies, but under high magnification. A videocapture.



9. Mayorella viridis the only free-living rhizopod with zoochlorellae. Found in a stream-side bog at Buckland Common, Dartmoor.



9a. M. viridis . A compressed specimen showing the vesicular nucleus.

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