Spring Thaw Collecting

by Richard L. Howey, Wyoming, US


Includes links to Micscape articles on some of the organisms mentioned.


Laramie sits on a high plain surrounded by mountains. Laramie, itself is at an altitude of 7,200 feet and to the east is a low range of mountains (the Sherman range) that rises to 8,600 feet; to the north is Elm Mountain; to the west is the Snowy Range with Medicine Bow peak at slightly over 12,000 feet and to the south is a low range that is part of the foothills of the central rib of the Rocky Mountains. The lakes on the high plain are highly alkaline and frequent wind produces considerable wave action. The blustery conditions are something that some people never accommodate to. There are local shops that sell T-shirts upon which is emblazoned:



Wherever one lives, there are always tradeoffs. For me, one of the most significant ones in Laramie is that we average over 300 days of sun. For me, this is quite important as I find prolonged periods of overcast skies rather depressing. Temperatures in the winter can be brutal. The coldest temperature I have experienced was 49 degrees below zero Fahrenheit, but that was 30 years ago and before the meteorologists had started reporting windchillsI don't even want to think about that. However, over the last 20 years the winters have gotten generally milder and this year we only had a few nights that dipped slightly below zero.

Why am I boring you with all this stuff about altitude and climate? Well, there are a couple of reasons. First of all, to try to give you an inkling of what a special event spring is for us and secondly, to give you a context for understanding that in some mountain areas during certain years, there are lakes that are not accessible until July! However, some years, in March we will get a week or two of brilliant, clear weather with temperatures in the 50s and the lakes in the plains begin to thaw, at least around the edges. There is the deceptive odor of spring in the air and my blood starts to tell me that it's time to be out with my bottles and nets. As I write this, it is late March and last week I was out collecting twice. The first time I went to Lake Sodergren about 20 miles southwest of Laramie. It was a dazzlingly clear day, the sky intensely blue and cloudless, the temperature near 60 degrees and a spectacular view of the snowcapped mountains in the distance. On the drive down, I saw a kestrel, an eagle, and several dozen antelope.

As early as it was, there were about a dozen other people out enjoying the day as well. I would like to report that they were all also avid microscopists, but unfortunately that wouldn't be true. Those others were out there fishing. I'm sure there is much to be said for the sport of fishing and there are many dedicated fishermen in this area; it's just something that never captivated me, even though, years ago as a young man, I tried reading Isaak Walton's The Compleat Angler. For me, there is a hierarchy involved and I think that all fishermen should also be microscopists! How can one go out to a lake or a pond or a river and not bring back samples of micro-life? There should be stiff fines for anyone caught fishing without also collecting. If these fishermen don't have the time to work through a particular batch of samples, then they should drop them off at one of the local retirement communities, all of which should be legally required to provide microscopes and laboratory facilities for the residents. This is just one aspect of my master plan titled: Making the World Safe For Microscopy.

O.K., O.K., I'll get to the topic. The primary reason for collecting at spring thaw is that one often encounters organisms that are absent or sparse the rest of the year and this is a consequence of two factors: 1) The gradual warming creates temperature gradients that cause movement in the water layers and makes a nutrient rich "soup" which is full of minute flagellates, algae and bacteria
all of which provide a rich food source for larger protists and 2) the still very cold water holds a higher concentration of oxygen than the warmer water of later spring and summer and naturally this ready availability of oxygen affects which species appear as the dominant organisms for those conditions.

At a large reservoir in the mountains to the east of us
one of my favorite collecting spotsI found hundreds of specimens of the elegant rotifer Asplanchna which looks like a lovely hand-blown Steuben crystal vase swimming gracefully through the water. Most years I don't get started collecting until mid-May and so previously I had found only the occasional specimen of Asplanchna. In this early spring collection, I also found specimens of the wonderful "jumping" rotifer Polyarthra which has bizarre appendages which almost look like feathers. There was also a large number of specimens of the rotifer Conochiloides which I had not seen before. The posterior half of this organism is embedded in a gelatinous matrix which frequently contains an egg or two. Another one of my favorites also made an appearance, the rotifer Kellicottia longispina. This marvelous creature has 3 long spines projecting from the anterior (oral) end and an even longer spine extending from the posterior end. They swim through the water as though participating in a highly formal regal processional and one can almost hear the strains of Elgar in the background. Rotifers are voracious feeders and the larger ones require enormous numbers of tiny flagellates, algae, and tiny ciliates. The water in these samples was in fact full of countless such beasties including dinoflagellates and the elegant colonies of Anthophysis. So, as you will readily realize, there is a wide variety of spring thaw organisms to study. I also found numerous specimens of Codonella cratera of the order Tintinnida which is a busy, bustling little ciliate swimming around in what looks like a miniature stone vase.

However, if you want to really study these organisms, plan to stay up for 48 hours after you get the samples home or buy a refrigerator. After 24 hours at room temperature, the population in the samples has undergone significant changes; after 48 hours, very few of the original organisms are to be found. The increase in temperature is in itself a major factor, because as the temperature rises the bacterial population increases at an exponential rate and with some samples, 48 hours is enough to produce a foul, vile, black, miasmic brew worthy of a lake from one of the lowest circles of Hell. By refrigerating the samples, the growth of bacteria is significantly slowed and the build-up of toxic by-products can be avoided for a considerable period of time.

I have a very small refrigerator of the sort that students use in their dormitory rooms and most of the time it is adequate. However, I must confess that if I were a computer software billionaire, I would build a house with a walk-in cold room to store thousands of samples. But, back to reality!

When you go collecting in early spring or late autumn, it's a good idea to take along two or three small plastic light-weight thermos bottles, especially if there is a considerable interval between the time of collecting and the time of refrigeration. Transfer the samples from the thermos flasks into containers for the refrigerator and label them. In this way, you can make a comparison between the populations of the samples kept constantly chilled and the samples collected and transported in the ordinary way.

For those of you with an interest in very small
flagellates and ciliates, spring thaw is an ideal time to collect as they appear in great variety and quantity. Many people avoid investigating these organisms because they think that they are all rather similar and consequently rather boring. Furthermore, they do require some rather careful observation and some good technique because they are so small. But with some patience and perseverance, there are some wonderful rewards to be had from examining these tiny enigmas. There is an amusing little hypotrich which appears to use its flagella like paddles in a rather drunken, staggering way. There are Peranema and Distigma which are rather comical in their movements. They both have a long flagellum which extends directly out from the anterior end like a rod, the tip of which flicks back and forth providing locomotion. In Distigma, the body is quite elastic and frequently seems to have a bulge which slides up and down the organism as it moves.

Sometimes one also encounters colonies of Synura in which the cells are beautifully arranged. If you are fortunate enough to get a specimen flattened under the cover glass so that you can examine it with the oil immersion 100x objective and if you can locate a cell which is illuminated in just the right way, you will be able to see extremely tiny scales and spines on the surface of the cell. Blooms of Synura sometimes give water an unpleasant odor and taste.

At this time of the year, one can often find significant numbers of bryozoan statoblasts and here the prevalent genus is
Plumatella. The colonies are difficult to find, but I have had reasonable success in raising colonies by starting with statoblasts collected in early spring. In sorting through the sample, I select out the statoblasts that look like they have begun to swell a bit. These are the ones most likely to "hatch" and produce colonies. I transfer these into clean artesian water or clean filtered pond water and add several pipets of small ciliates and flagellates to serve as food. Once a polyp appears, I feed the culture every 2 or 3 days. In this way I have been able to raise and keep colonies going for over 3 months.

An interesting study can be done by selecting a specific site at a pond or lake and monitoring it through the collecting season beginning with spring thaw. A record of air and water temperatures, vegetation, and micro-flora and fauna can provide an interesting account of populations shifts in a tiny part of the aquatic world.

Comments to the author Richard Howey welcomed.

Editor's note:
The author's other articles on-line can be found by typing 'Howey' in the search engine of the Article Library, link below



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