Chapter XVIII 



— 203 — Microbiology of Inland Waters 



feed on bacteria, small plants, and small protozoans. The brine shrimp, 

 Artemia gracilis, which abounds in the lake, was shown by Jensen (1918) 

 to be an obligate halophile. Lake water diluted to a specific gravity of 

 1.044 to 1.027 was found to be most favorable for the development of 

 Artemia. The specilic gravity of undiluted lake water is about 1.15. 



In his review of the literature on life in Great Salt Lake, Eardley 

 (1938) lists the brine shrimp, 3 flies, 5 protozoans, and 13 species of algae. 

 He relates that at times the brine shrimps "congregate in such numbers 

 as to tint the water over wide areas." During certain years the puparia 

 of the fly Ephydra were reported to drift upon the shore in long windrows, 

 and countless swarms of the adult flies were observed over the water, in 

 which they drop their eggs freely. The extensive calcareous bioherms 

 along the exposed lake shores were believed by Eardley to consist princi- 

 pally of deposits of the alga, Aphanothece packardii, although the possible 

 importance of bacterial activity in the precipitation of the carbonate 

 deposits was not overlooked. 



The occurrence of small algae in the lake has' been reported by various 

 investigators. However, the extent to which they are growing in the un- 

 diluted brine is problematical. According to Patrick (1936), who identi- 

 fied 24 genera and 62 species of diatoms from lake bottom samples, no 

 diatom flora is found living in the lake proper today. Patrick avers that 

 the living forms reported from the lake have been found, no doubt, in the 

 surrounding brackish marshes and river estuaries which have a much 

 lower salt concentration. Flowers (1934) stated that the lake water 

 proper harbors six species of algae, including four Myxophyceae and two 

 Chlorophyceae. Numerous additional species were found in surrounding 

 brackish water. 



An abundant bacterial flora representing several genera was observed 

 on glass slides submerged in the lake by Smith and ZoBell (1937). The 

 development of micro-colonies on the submerged slides established that 

 the bacteria multiplied in the brine and were not merely passive inhabi- 

 tants. Daines (1917) demonstrated the presence of from 200 to 625 

 bacteria per ml. of lake water by plate count procedures. Pigmented rods 

 predominated. 



The decomposition of organic matter in the lake was regarded as evi- 

 dence of bacterial activity. ZoBell et al. (1937) found an average num- 

 ber of 167 bacteria per ml. which formed colonies on nutrient lake-water 

 agar. IMost of the organisms proved to be obligate halophiles whose 

 growth required 6 to 15 per cent NaCl. Sea water was found to be little 

 better than fresh water for the cultivation of lake bacteria. Conversely, 

 very few marine, soil, and sewage bacteria were able to grow in media pre- 

 pared with undiluted water from Great Salt Lake. This is illustrated by 

 the data in Table XLII. 



Table XLII. — Relative numbers of bacteria from diferent sources which developed on nutrient 

 agar prepared u-ith various dilutions of Great Salt Lake water {L.W.), fresh water, and sea water.— 



