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Aspects of the Limnology of an Endorheic African Lake (L. Chilwa, Malawi)
Author(s) -
Moss Brian,
Moss Joyce
Publication year - 1969
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1934668
Subject(s) - limnology , hydrology (agriculture) , salinity , environmental science , alkalinity , nitrate , wetland , turbidity , water level , crater lake , salt pan , hypolimnion , periphyton , dry season , ecology , geology , algae , nutrient , chemistry , biology , geography , eutrophication , paleontology , geotechnical engineering , cartography , organic chemistry , volcano , seismology
Owing to relatively low rainfall during the past few years, Lake Chilwa (15°S, 36°E), lake with internal drainage, is on the verge of complete drying out. The results of chemical and biological investigations undertaken whilst water was available are presented. A fluctuation between high dry season and lower wet season levels of major ions was found. It is likely that salts in the lake originated primarily from salt springs, rather than from evaporation of inflowing river water. Inorganic phosphate and nitrate were sometimes not detectable in the water, but were released in large quantities following flooding of the marginal mud—flat. The lake was classified as moderately saline (Class II, Talling and Talling 1965) in 1966/67, but as a result of evaporation salinity and alkalinity increased sufficiently for it to become a Class III lake in 1967/68. At high water levels fish production was high, possibly as a result of extensive digestible diatom crops on the sediment surface. Factors limiting primary productivity included light intensity, as a result of high turbidity and water color, and low levels of nitrate.