CHANGING DIATOMS OF DEVILS LAKE 
CLARENCE J. ELMORE 
During the summer of 1915 I spent some time at the Biological 
Station of the University of North Dakota at Devils Lake, investi- 
gating the diatoms of the lake. Before this considerable diatom 
material had been sent to me by Dr. R. T. Younc of the University, 
who is conducting the biological survey of the lake. 
The immediate practical object in the survey is to determine 
the organisms in the lake in relation to the fish that might be able 
to subsist upon them, and diatoms being the most abundant of 
microscopic plants, deserve special attention in this connection. 
At present the stickleback, Eucalia inconstans, is the only species 
of fish in the lake, notwithstanding the fact that food is abundant. 
This species, however, is common. 
The lake is passing through a rapid transition. It was formerly 
a fresh-water lake fed by streams, and at that time it contained large 
numbers of fish, but the lake is rapidly becoming lower. From 
1883 to 1912 it fell 14 ft., a fall of about half a foot a year. It has 
now no apparent inlet or outlet, and the water is becoming salt. 
The salinity, however, is quite different from that of sea water. 
It differs somewhat in different parts of the lake and at different 
seasons of the year, but the following analyses made by Dr. F. H. 
HEATH of the University of North Dakota in the summers of 1914, 
1915, and 1916 will give a general idea of the condition of the water. 
No complete analysis was made in 1915, but the total amount of 
solids in that year was greater than in 1914 or 1916, due to the lower. 
level of the water. 
1914 IQls 1916 
Ot See Cet es. Oe ea eas 254 O14 ue 
Bicarvonete (CO)... sa 447 6 
Silica (SiO,) variable... ......... co, ene 242 and 69 
monte (SO a Ont. 67 
Feji, ant ALD eo ne 121 
Caiciom (Ca) vitae. (3. .6 os 86.5 
Magnesium (Mg). ...:.......... Soe 2, 579 
Chiorins (0) 13106 ke. 1284 
Toteheenee. 2... ek .. 11,980 14,477 13,020 
Botanical Gazette, vol. 65] {186 
