**Characteristics of Soda Lakes:**
– Soda lakes have a pH between 9 and 12.
– They contain high concentrations of carbonate salts like sodium carbonate.
– Many soda lakes also have high sodium chloride levels.
– Soda lakes are highly alkaline and hypersaline.
– They are extreme aquatic environments on Earth.
**Biodiversity in Soda Lakes:**
– Soda lakes host a diverse microbial population.
– Microbial life in soda lakes is highly concentrated.
– Algae blooms with varied colors are common in soda lakes.
– Prokaryotes dominate life in soda lakes.
– Some soda lakes support crustaceans, fish, and flamingos.
**Microbial Diversity and Species Richness:**
– Microbial biodiversity in soda lakes is understudied.
– Photosynthesizing cyanobacteria and algae are primary producers.
– Molecular methods like DNA fingerprinting are used to study diversity.
– Culture-independent surveys show high microbial diversity in soda lakes.
– 16S ribosomal RNA gene clone libraries reveal unique bacterial communities in soda lakes.
**Productivity and Ecology of Soda Lakes:**
– Soda lakes are highly productive ecosystems.
– Gross primary production rates in soda lakes are over 16 times the global average for lakes.
– Photosynthesis is the primary energy source in soda lakes.
– Methanogens in lake sediments produce methane.
– The availability of dissolved carbon dioxide contributes to high productivity.
**Biogeography and Nutrient Cycling in Soda Lakes:**
– Soda lakes harbor unique species adapted to alkalic conditions.
– The biodiversity in soda lakes is distinct from freshwater ecosystems.
– Cyanobacteria dominate surface photosynthesis in soda lakes.
– Sulfur-reducing bacteria reduce sulfate to sulfide in anoxic layers.
– Nitrogen is a limiting nutrient in soda lakes.
A soda lake or alkaline lake is a lake on the strongly alkaline side of neutrality, typically with a pH value between 9 and 12. They are characterized by high concentrations of carbonate salts, typically sodium carbonate (and related salt complexes), giving rise to their alkalinity. In addition, many soda lakes also contain high concentrations of sodium chloride and other dissolved salts, making them saline or hypersaline lakes as well. High pH and salinity often coincide, because of how soda lakes develop. The resulting hypersaline and highly alkalic soda lakes are considered some of the most extreme aquatic environments on Earth.
In spite of their apparent inhospitability, soda lakes are often highly productive ecosystems, compared to their (pH-neutral) freshwater counterparts. Gross primary production (photosynthesis) rates above 10 g C m−2 day−1 (grams of carbon per square meter per day), over 16 times the global average for lakes and streams (0.6 g C m−2 day−1), have been measured. This makes them the most productive aquatic environments on Earth. An important reason for the high productivity is the virtually unlimited availability of dissolved carbon dioxide.
Soda lakes occur naturally throughout the world (see Table below), typically in arid and semi-arid areas and in connection to tectonic rifts like the East African Rift Valley. The pH of most freshwater lakes is on the alkaline side of neutrality and many exhibit similar water chemistries to soda lakes, only less extreme.