production was accelerated however was even- 

 tually made evident by the growth and popula- 

 tion increases observed in the fish biomass, as 

 well as by the observable gain in numbers of 

 zooplankton detected in 1957. 



SUMMARY 



1. Bare Lake, a small, shallow, unstrati- 

 fied lake on Kodiak Island, Alaska, was arti- 

 ficially fertilized with di-ammonium phosphate 

 and sodium nitrate each summer from 1950 

 through 1956. 



2. Nelson and Edmondson (1955) report that 

 at the end of the third season of fertilization 

 (1952), it was determined that fertilization had 

 (1) increased the rate of photosynthesis, (2) in- 

 creased the phytoplankton population many- 

 fold, (3) increased the pH of the water, and 

 (4) decreased the transparency, but (5) had 

 little or no detectable effect on the net zoo- 

 plankton population. 



3. The 1957 zooplankton population, although 

 inhabiting a shallow (7,5 m. ) lake, displayed a 

 definite variation in depth distribution when 

 considered by species that was not apparent 

 when the population was considered as an 

 entity. 



4. By 1957 the zooplankton had increased 

 at least threefold over the 1952 abundance. 

 The delay in increase observed may have 

 been due to effective cropping by predators, 

 perhaps complicated to someextentby the slow 

 life cycle of the planktonic entomostraca. This 

 same pattern of delayed response was re- 

 corded by Waters (1956) in a hydrated lime 

 study in two Michigan ponds where predation 

 may or may not have been a factor. 



5. The Bare Lake zooplankton abundance 

 for 1957 was comparable with the zooplankton 

 abundance of five small Colorado lakes. 



Larkin of the University of British Columbia, 

 for their helpful suggestions and critical re- 

 view of the manuscript. The plankton organisms 

 were identified by:D. M, Hammond, Protozoa; 

 W. T. Edmondson, Rotifera; M. S. Wilson, 

 Copepoda; and D. K. Milliard, Cladocera. 

 John B. Owen of the Bureau of Commercial 

 Fisheries, materially assisted the study in 

 the field. 



LITERATURE CITED 



EDMONDSON, W. T. 



1957. Trophic relations of the zooplankton. 

 Transactions of the American Micro- 

 scopical Society, vol. 76, no. 3, p. 

 225-245. 



1960. Reproductive rates of rotifers in 

 natural populations. Memorie 

 deiristituto Italiano di Idrobiologia dott, 

 vol. 12, p. 21-77. Pallanza. 



KUTKUHN, JOSEPH H. 



1958. Notes on the precision of numerical 

 and volumetric plankton estimates from 

 small-sample concentrates. Limnology 

 and Oceanography, vol. 3, no. 1, p. 69- 

 83. 



LANGFORD, R. R. 



1953. Methods of plankton collection and a 

 description of a new sampler. Journal 

 Fisheries Research Board of Canada, 

 vol. 10, no. 5, p. 238-252, 



NABER, HELMUT. 



1933. Die Schichtung des Zooplanktons in 

 holsteinischen Seen und der Einfluss 

 des Zooplanktons auf den Sauerstoffge- 

 halt derbewohntenSchichten. Archives 

 d'Hydrobiologie et d'Ichthyologie, vol. 

 25, no, 1, p. 81-132. [Cited from 

 Ricker, W, E., 1938, Journal Fisheries 

 Research Board of Canada, vol. 4, no. 1, 

 p. 19-32.] 



ACKNOWLEDGMENTS 



Acknowledgment is made of the assistance 

 of D. M. Hammond, W. F. Sigler, and T. L. 

 Bahler of Utah State University, and P, A. 



NELSON, PHILIP R., and W. T. EDMONDSON, 

 1955. Limnological effects of fertilizing 

 Bare Lake, Alaska. U.S. Fish and Wild- 

 life Service, Fishery Bulletin 102, vol. 

 56, p. 415-436. 



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