Studies on Some Limnological Variables in Subtropical Lakes of the Pokhara Valley, Nepal

Abstract

Some limnological variables were investigated and analyzed in Phewa, Begnas and Rupa Lakes of Nepal in the late-monsoon and dry seasons. From the data on the levels of TN, TP, Chl. a and phytoplankton primary productivity, Phewa Lake seemed to be meso-eutrophic, and Begnas and Rupa Lakes to be eutrophic. The gradient of the regression line of PC on Chi. a ranged from 42.1 to 71.4 and suggested that phytoplankton in the investigated lakes had a moderately high or high relative growth rate. In comparing the C : N : P : ratios of the seston with REDFIELD Ratio and other data on phytoplankton chemical ratio, all the lakes appeared to be P-limited. Variation of species diversity of phytoplankton was great between both the seasons in each lake and tended to depend mainly on the share of the predominant species, Microcystis aeruginosa, in total cell number in Phewa and Begnas Lakes, and on that of Tabellana fenestrata in Rupa Lake. The similarity index of phytoplankton indicated that phytoplankton in Phewa Lake were similar to those in Begnas Lake but not to those in Rupa Lake. © 1988, The Japanese Society of Limnology. All rights reserved.