Repetitive Observations

(Project Update: Diatoms & Desmids of the U.S.A.)

When taking a casual survey of the micro-organisms in a body of water, one or two observations of the same organism are sufficient. When making a serious population study, however, this is not the case. In a population study it is necessary to determine which organisms are permanent residents and which are transients. There are many variables that enter the study (temperature, pH, time of the year) that can influence changes in the population. That makes it necessary to document an organism every time it is encountered. I treat each lab session examining the same sample as a separate entity. I do not allow the results of yesterday’s session to influence what I record in today’s. One session typically consists of two or three slides, and I find that one sample will normally last for three days; after that it loses its vitality. A sample large enough to fill a ten gallon aquarium would probably have a longer shelf-life, but my usual sample is a pint or less.

Posted on April 30, 2013 03:33 PM by william_dembowski