Last month's splendidly atmospheric description of making a study of life in torrents by William H. Amos, of Vermont, United States took me back to days foraging in the Dolomites of Northern Italy in the 80's and irregular visits to the Carpathians in the early 90's. It reminded me of the problems of collecting; particularly diatoms, and other algae in the flumes and their spray zones and in the moist overhangs of "Where Eagle's Dare" country.
In the past a large number of incredibly ingenious gadgets have been adapted for this rather hostile environment. The inventions have mainly been based on syringes large and small, designed to function at "arms length" by the release of compressed springs. Mere receptacles like spoons are soon torn from the hand or emptied by water pressure before they are filled.
One day when I found an underwater wall of rock covered in slimy diatoms. I realised that I had all I needed in my rucksack. If a flat plastic bath sponge is held firmly against the rock below the surface and is wiped in an upward direction until it emerges from the water, it becomes impregnated with the growth which can then be squeezed out into an empty 'Panda' ® type pop or lemonade bottle. The addition of a small plastic funnel completes the apparatus.
This same apparatus is also excellent for the washing of stones from the more shallow streams. The algal growth can be loosened from the stones in the funnel with an old toothbrush and irrigated with a small amount of the parent water. Both of these methods produce samples of diatoms that are concentrated enough to warrant processing. Labelling with waterproof marker pens is also required, and sponge cleaning to avoid the mixing of samples is also an important consideration after collection.
The set-up later proved to be quite
useful in a wide variety of situations where scraping was not
very suitable. Wooden piers and harbour walls in tidal
harbours were an excellent application.
Comments to the author Brian Darnton welcomed.