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Gilbert, Charles H., and Willis H. Rich. 
1927. Investigations concerning the red-salmon runs to the Karluk River, Alaska. Bulletin, 
U. S. Bureau of Fisheries, Vol. XLIII, Part II, 1927 (1929), pp. 1-69, 34 figs. Wash- 
ington. 
Halbfass, W. 
1923. Grundziige einer vergleichenden Seenkunde. 1923, 354 pp., 110 figs. Berlin. 
J LTD AY, CHANCEY. 
1916. Limnological apparatus. Transactions, Wisconsin Academy of Sciences, Arts and 
Letters, vol. 18, No. 2, 1916, pp. 566-592. Madison. 
Kemmerer, George, J. F. Bovard, and W. R. Boorman. 
1923. Northwestern lakes of the United States: Biological and chemical studies with reference 
to possibilities in production of fish. Bulletin, U. S. Bureau of Fisheries, Vol. XXIX, 
1923-24 (1924), pp. 51-140, 21 figs. Washington. 
Martin, G. C. 
1913. Mineral deposits of Kodiak and neighboring islands. In Mineral resources of Alaska, by 
Alfred H. Books and others. Bulletin No. 542, U. S. Geological Survey, 1913, pp. 125- 
136. Washington. 
Mulley, G. 
1914. Analysen des Schlammes der Lunzer Seen. Internat. Revue gesamten Hydrobiologie 
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Shostrom, 0. E., R. W. Clough, and E. D. Clark. 
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Washington. 
Part II. DIATOMS OF THE BOTTOM DEPOSITS OF KARLUK 
LAKE 
By Albert Mann 
During the course of certain investigations relating to the red salmon of Karluk 
River, Kodiak Island, Alaska, the investigators of the United States Bureau of 
Fisheries have secured limnological data in Karluk Lake and the two smaller lakes, 
Thumb and O’Malley, which are tributary to the main lake. These lakes have been 
surveyed and described by Gilbert and Rich (1927). In 1927 samples of the bottom 
deposits were secured by means of an Ekman dredge. A chemical analysis showed 
an unusually high silicon content in the deposits of each of these lakes (Black, 1929). 
It seemed probable that this was due to an abundance of diatoms and eight samples 
were submitted to the writer for study. All are high in diatom content, some of them 
remarkably so, from 80 to 90 per cent, which accounts for the high silicon content. 
The great richness and nutritive value of this bottom material is worthy of note. 
The data bearing on the samples and remarks on the general character of their 
composition are given below : 
1. Lower basin, Karluk Lake ( station 8) 50 meters, July 19, 1927.- — Nearly pure 
diatoms, 80 to 90 per cent of the mass. Mostly two species, Cyclotella Bodanica and 
Stephanodiscus Niagarae, the former outnumbering the latter 3 to 1. Scanty repre- 
sentatives of Cymbella Mexicana var. Kamtschatica, Gomphonema herculeanum, 
Epithemia Zebra, Navicula tenella, Melosira Italica, Amphora ovalis, Surirella robusta, 
etc. 
2. Thumb Lake, 10 meters, July 21, 1927. — 80 to 90 per cent diatoms; as in the last, 
mostly Cyclotella Bodanica and Stephanodiscus Niagarae in ratio of 3 to 1. Also 
