Microbial Community Aquatic bacteria, algae, fungi, and protozoa have demonstrated high evolutionary adaptability to salinity changes and as a result, halophiles are widespread in all three domains - Archeae, Eubacteria, and Eukarya. In fact, some bacteria can exist up to NaCl saturation. A common benthic feature of many saline lakes is microbial mats formed by an association between cyanobacteria, bacteria, and algae. Cyanobacterial mats in the Salton Sea, California, contain several filamentous cyano-bacteria, including Oscillatoria spp. and Geitleri-nema spp. as well as unicellular cyanobacteria, small diatoms, and Beggiatoa, a sulfur oxidizing bacteria. It is thought that cyanobacteria, particularly the mat forms associated with Beggiatoa, may play an important role in carbon fixation and other bio-geochemical processes in the Salton Sea.
Numerous algal species are highly adapted to saline conditions as well. In a study of 41 saline lakes across southern Saskatchewan, Canada, ranging in salinity from 3.2 to 428 g l-1, algae in 7 phyla, 8 classes, 42 families, 91 genera and 212 species were identified. Fourteen species were restricted to hypersaline (50 gl-1; 50%) waters and eleven of these were diatoms. Generally, species diversity was inversely related to lake salinity.
Important community constituents over a wide salinity range were green algae, cyanobacteria, and diatoms. Commonly, green algae dominated when lake salinity exceeded 10.0 g l-1 (10%). In some saline lakes, models developed for temperate freshwater lakes that predict algal biomass from either ambient total phosphorus or nitrogen concentration routinely overestimate chlorophyll a and primary production. As well, bacteria in some saline lakes are phosphorus limited despite high measured concentrations of biologically available phosphorus. Some aspect of salinity and high levels of dissolved organic carbon, which may inhibit algae and/or bind phosphorus, may explain these anomalies.
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