Observations on the Conditions of Existence of a Green Sulphur Bacterium in Sodon Lake, Southeastern Michigan

Environmental Factors of Sodon Lake‐‐A Dichothermic Lake in Southeastern Michigan

“…Any small amounts which did reach upper levels were probably oxidized. As pointed out by Newcombe & Slater (1950) the Chlorobium stratum marks the beginning of an abrupt increase in hydrogen sulphide. Dutton & Juday (1944) report a concentration of 2.5 mg. per I. in the bottom layers of Scaffold Lake, Wisconsin where Chlorobium is exceedingly abundant at all depths.…”

“…Biological assays included measurements of the amount of centrifuged (particulate) organic matter and of the amount of attachment materials on a standard area of submerged glass surface per unit of time. The latter data are reported upon in a separate paper (Newcombe 1950). The methods for measuring these indices of water productivity followed the pattern used by Birge & Juday (1922) and Newcombe (1949 and.…”

“…Monthly trends in respect to air temperature, hours of sunshine and precipitation are given in Figure 2. It has been indicated by Newcombe & Slater (1949) that the thermocline in summer approaches exceedingly close to the surface (compare Smith 1940, p. 284). Figure 3 shows that below a depth of 30 feet there is very little seasonal change in the water temperatures.…”

“…To aid in comparing the light as well as certain chemical factors in Sodon and Walnut Lakes, reference is made to Figure 6 taken from Newcombe & Slater (1949). Seasonal differences in the vertical trends of temperature in Sodon Lake are demonstrated and it is also shown that the bottom temperatures are higher in Walnut Lake.…”

“…It has been shown by Newcombe & Slater (1948, 1949 that Sodon is a dichothermic lake, one of three known natural lakes of this type in the United States. 1 The physical, chemical and biological prop-' A fourth dichothermic type is Bi1< Soda Lake.…”