Seasonal Characteristics of Two Saline Lakes in Washington

Abstract

The limnology of two highly saline lakes in Washington was studied in relation to the physical and chemical conditions which influence the growth and distribution of phytoplankton. The lakes were sampled at frequent intervals for a period of more than a year in 1950 and 1951. Morphometric conditions were determined, and routine sampling included measurements of temperature, transparency, oxygen, pH, alkalinity, phosphate, chlorophyll, and quantitative samples of phytoplankton. Lake Lenore, the less saline of the two (T.D.S. 14 g/liter), is shallow and was unstratified during the investigation. Dissolved nutrients were high and showed erratic variations during the summer. The phytoplankton population was taxonomically simple and was made up mainly of two species of diatoms—Amphora sp. which formed the spring bloom, and Chaetoceros elmorei which made up the late summer bloom. Soap Lake is relatively deep, meromictic, and saline (T.D.S. 35 g/liter). Temperature conditions were dichothermic, and the nutrient content was high, especially in the monimolimnion. A winter maximum and a summer minimum was observed in the phytoplankton population, and a change in the biota has been noted during dilution of the lake in recent years. Indication of grazing by zooplankton was found in both lakes.