Chapter XVIII — 207 — Microbiology of Inland Waters 



DuGGELi (1924) was one of the first to make extensive use of selective 

 media specifically designed to estimate the relative abundance of various 

 physiological types of bacteria in Lake Ritom in Switzerland. He was 

 particularly concerned with the factors which influence the removal of 

 oxygen and the occurrence of H2S. The formation of the latter was shown 

 to be due to the activities of Destilfovibrio desulfuricans. The H2S was 

 oxidized either abiogcnically or by certain sulfur bacteria, thereby deplet- 

 ing the oxygen. Chromatium species occurred in sufficient abundance in 

 the boundary zone between the overlying oxygenated water and the 

 deeper, HoS-containing water to cause a rosy red color. In the bottom 

 water of Lake Ritom, Duggeli found up to 30 mgm./L. of HoS, a concen- 

 tration which was toxic for nearly all forms of life, including most bacteria 

 except those that produced H2S by reducing sulfates. 



Klein and Steiner (1929) made quantitative studies on ammonifica- 

 tion, nitrification, nitrogen fiixation, nitrate reduction, and sulfate reduc- 

 tion in Lake Lunz. Their comprehensive activity determinations gave 

 new impetus to the study of hydrobacteriology. 



Seasonal fluctuations in the ammonia, nitrate, and oxygen content of 

 Lake Mendota were found by Domogalla et al. (1926) to be due almost 

 entirely to bacterial activity. Increases in bacterial numbers were gener- 

 ally accompanied by increases in ammonia. An increase in nitrification 

 followed the production of ammonia except in waters deficient in oxygen. 

 From 800 to 3800 bacteria per ml. of water were found, with little evidence 

 of seasonal or vertical variations. 



Baier (1935) noted a close correlation between chemical, physico- 

 chemical, biological, and bacteriological conditions in five shallow lakes 

 around Kiel. The foul odor emanating from the Little Kiel, a black, 

 brackish backwater within the city limits of Kiel, was shown to be due 

 to the activities of sulfate reducers. Several factors which influence the 

 numbers, kinds, and activities of microorganisms in inland waters were 

 examined with the help of much relevant literature and original research. 

 Baier stressed the importance of microorganisms as biochemical agents 

 and as a food source for aquatic animals. 



More intensive and extensive studies on the activities, distribution, 

 and characteristics of aquatic microorganisms are needed in order to gain 

 a complete understanding of the productivity, metabolism, and ecology 

 of bodies of water. While hydrobacteriological research can contribute 

 much to the pure science of bacteriology, its chief objective should be an 

 elucidation of general hydrobiology, biochemical and geological processes 

 in bottom deposits, and other practical problems. The importance of 

 hydrobacteriological research was emphasized by Thienemann (1927) in 

 a ten-year progress report of the Hydrobiological Institute Plon of the 

 Kaiser Wilhelm Society. A literal translation of his statement follows: 



"The greatest need of limnology, the satisfaction of which would be 

 of benefit to many associated departments, is bacteriological information. 

 It may be momentarily surprising if I insist that hydrobacteriology as 

 such is virtually non-existent. It is true that there have been investiga- 

 tions regarding bacteria living in water, but for the most part they have 

 had reference primarily to practical hygienic problems. It is well known 

 that bacteria play an extremely important part in the cycle of life- 

 materials; it may even be the most important part, if we are justified in 

 assigning degrees of importance. No matter how detailed may be our 

 methods in water chemistry, even the most intensive delving into purely 



