Collecting Freshwater Life

by William Ells
Coniferae, Walnut Tree Lane, Loose, Maidstone, Kent. ME15 9RG.

How NOT to collect freshwater life. My wife and I were walking a farm trail at Marden, Kent. A mixed farm with hops, fruit and sheep and a plantation of Salix alba a cultivar coerulea or cricket bat willow. At one point it passes close to the river Beult. I decided I would collect some water although I had set out with no intention to collect and did not have my rod and net with me, but I usually have a tube or two in my pocket.

Going down to the water edge I filled one of the little tubes, turned to come up the bank when my feet started to slip into the water, thinking I would go in up to my knees I was surprised to find myself going right under. When I came up I found the water was chest high and my straw hat was slowly floating away. I grabbed my hat and passed it to my wife who then helped me out of the river and up the bank.

I stripped off my shirt and shorts, my wife wrung out my shirt and I did the same with my shorts and put them back on. My shirt felt too clammy to put back on so we walked on a short distance to an open field where I hung my shirt on a tree branch and sat in the sun to dry out. Fortunately it was a warm day.

A note or two on a better way to collect may not come amiss. Nearly every introductory book on algae and protozoa has some instructions on collecting. There is a very comprehensive account on collecting Rotifera by Eric Hollowday in Microscopy (Journal of the Quekett Microscopical Club) 1985, Vol. 35, part 3, which also applies to other forms of microscopic aquatic life.

Collecting Net

Some years ago a friend kindly gave me a small net with a collecting tube. I bought an anglers extending landing net rod which extends to about 7 feet, made a frame of wire four inches square on which to fit the net, fitting same to the end of the rod with a screw clip of the type used to fit rubber tubes on car radiators. I have found this very useful although the mesh, screen printers 'silk', has apertures of about 100 microns, twice that recommended by Hollowday, as you may lose very small forms through the mesh.

I have since been given a wooden rod and net said to have been supplied by Watsons. The rod is just under 3 feet long with a six inch diameter brass ring with a screw fitting to the end of the rod. The net, with apertures of about 90 microns was perished so I have replaced this with a net of screen printers fabric as above, using the original tube. See sketch of net and tube (Figure 2, after Hollowday).


For plankton organisms, the net is immersed and 'figures of eight' described in the water, keeping the net moving all the time. When the net is removed from the water it is allowed to drain, the water and organisms which do not pass through the net will fall into the tube which is then emptied into a larger vessel (jam jar will do). Unwanted macro organisms can be removed if the tube is emptied into a coffee strainer placed across the top of the jar.

A), D) Water level in net
B) Water draining through net
C) Plastic tube looks clear
E) Concentrated organisms falling into tube

Diatoms and Desmids can be gathered by scraping the edge of the net up some stems of water plants and passing through any growth of filamentous algae. If you are using a square net try passing it gently along the bottom of small pools, some of the submerged filamentous algae that can be reached from the bank can be collected and put into a plastic bag.

In boggy areas the water from a little of the wet moss can be squeezed into a collecting tube or a little put into a plastic bag and sealed for later examination. NOTE: it is not necessary to take large quantities of water or moss, better to take a little from several sites. If you have a good collection it will take hours to examine 100ml. of water under the microscope if you make the effort to identify all the organisms you find.

Comments to Bill Ells welcomed.

Editor's note
The Micscape Editor thanks William Ells for contributing this article, which first appeared in Balsam Post the quarterly magazine of the Postal Microscopical Society, UK. Note that Bill Ells has written a number of articles on desmids which are an attractive and fascinating algae, including an
Introduction to the Desmids. All these articles can be found in our Articles Library in the Pond-life section.


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