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Abstract
A cyanobacterium of the genus Cyanobium is found in alkaline hypersaline Mono Lake,California. I have studied its spatial and temporal distribution using epifluorescence microscopy and measured growth characteristics of an isolate (MLCB) to gain insight into the physiological4-ecology of the organism. The Mono Lake Cyanobium blooms in late summer (5.0 x 10 cells mL12). It has very low population densities in photic waters through spring and summer (<10 cells-145-1mL), but maintains a significant population of cells (10 to 10 cells mL) year round below 25meters during meromictic periods. Complete turnover of the lake resulted in a large decrease(90%) in deep water cell concentrations. Bathymetric data was used to calculate the total number of cells at various depths throughout the lake to help determine whether sedimentation and/orlittoral transport affected its distribution. Comparison of the salinity tolerance of MLCB to other members of the genus showed that strain MLCB was the most halotolerant, capable of growing at 10% salinity, compared to limits of 0 to 6% for the other strains.