Workshop on diatoms from Lake Mývatn, Iceland
Saturday 23rd February 2019
Apologies for the lack of photographs, but the card in my camera failed and I could recover only 3 of them. Chris Thomas is editing his video, and it will be available here.
Paul Smith introduced the workshop by showing us some photographs from his trip to Iceland in 2001. Lake Mývatn used to be famous for its cabbage-size colonies of the filamentous green alga Aegagropila linnaei, but they have disappeared because of pollution. The lake was not on the itinerary but Paul managed to arrange a visit and collected some diatoms.
Paul Smith introducing the workshop
The equipment that Paul provided included a hotplate with several metal nuts on top (for placing coverslips with a drop from a jar of cleaned diatoms until the water had evaporated), a template for lining up cards on slides, pipettes, and forceps for handling coverslips.
Paul Smith showing how to make dry mounts
Paul also provided slides, coverslips, square pieces of black card with a circle cut out, and labels. Some of the black cards had double-sided clear tape on both sides, other cards had tape on only one side. The procedure was:
- Put a drop of water with diatoms on a coverslip.
- Put the coverslip on a nut on the hotplate (it would be very difficult to pick up a coverslip from the surface of the hotplate).
- Wait for the water to evaporate.
- Take one of the cards with tape on both sides, remove the protective film from one side, and stick it on the slide (using the template to get it in the middle).
- Remove the protective film from the other side.
- Put the coverslip (specimens on the underside) on the card.
- Take one of the cards with tape on one side, remove the protective film, and stick it on top of the first card, so that the coverslip is sandwiched between the 2 cards.
- Add a label.
The black card was cut from A4 sheets 240 gsm, available from stationers, art shops, etcetera.
The double-sided tape was Premium White Double Sided Tape – 33m × 25mm (1″) by Gocableties.
The punch for making holes in the card was EK Success brand, ¾ inch, available from The Range or from Amazon. Jacky McPherson advised that these punches can be sharpened by punching holes in aluminium foil.
The labels that Paul provided were printed on a Brother P-Touch 2420PC using a 24 mm PZ-Tape. The labels were edited on a PC and sent to the printer via USB.
The template for lining up the cards (or coverslips) on a slide was …
A couple of the Club’s compound microscopes were available for examining the finished slides.
Jacky McPherson took her slides home and photographed some of the diatoms.
Epithemia sp. [by Jacky McPherson]
Surirella sp. [by Jacky McPherson]
Dennis Fullwood used the Club’s Chinese inspection camera and Iiyama monitor to show a fossil trilobite and some insects in amber.
Free to a good home
Two members brought along items they no longer required, free to a good home. These included a Leitz dark-ground condenser, a Lensman pocket microscope with camera attachment, Baker and Cooke objectives, clear and frosted stage glasses for stereomicroscopes, filters, slide boxes, slide holders, small Petri dishes and several other items. This proved to be very popular, and it would be good to see it become a regular feature.
Report and most photographs by Alan Wood, video by Chris Thomas