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LIMNOLOGICAL STUDIES AND FISH YIELD IN THREE UPLAND LAKES OF MADRAS STATE, INDIA
Author(s) -
Sreenivasan A.
Publication year - 1964
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1964.9.4.0564
Subject(s) - alkalinity , plankton , eutrophication , algae , carbon dioxide , environmental science , zoology , biology , ecology , nutrient , chemistry , organic chemistry
The general conditions, primary production, and fish yield were studied in three upland lakes in tropical Madras State. Kodaikanal Lake had a poor but predominantly desmid plankton, high transparency, low dissolved solids, low alkalinity, low hardness, low pH, and no phosphorus or calcium. Primary production in this lake was the lowest among the three lakes, averaging 0.46 g carbon fixed m −2 day −1 . Yercaud Lake, at a lower altitude, had a predominantly cyanophycean plankton throughout the year, and the salt content and primary production, averaging 2.9 g C m −2 day −1 , were higher than that in Kodaikanal Lake. Near‐bottom oxygen deficits and carbon dioxide accumulations were typical of Yercaud Lake. Ooty Lake, polluted by sewage, had the highest rate of primary production, averaging 3.8 g C m −2 day −1 , a high plankton volume, and higher electrical conductivity, alkalinity, hardness, calcium, and pH. The plankton was dominated either by blue‐green algae or by the flagellate, Ceratium hirundinella. This lake is eutrophic, but the pH rarely rose above 7.5, and marked changes in it were not observed. Carbon dioxide accumulation near the bottom was not common, although oxygen depletion was. There were regular diurnal and vertical variations in pH in Yercaud Lake, indicating a high degree of photosynthetic and metabolic activities. Fish production was lowest in Kodaikanal Lake, 5.3 kg/hectare, intermediate in Yercaucd Lake, 31.6 kg/ha, and highest in Ooty Lake, 75 kg/ha. Less than 0.2% of the primary production is utilized in these three lakes.