Cyanobacteria, also called blue-green algae, are historically entwined with the evolution of Earth. They convert sunlight, water, and carbon dioxide into oxygen and organic matter. When nutrients abound, they bloom.
About Cyanobacteria
Cyanobacteria are believed to have originated over 3.5 billion years ago. These microorganisms are among the first photosynthetic life forms. Fossil evidence shows tiny microscopic colonies to intricate layered structures.
Although called algae, these are bacteria. Their ability for photosynthesis is major factor of change. By converting sunlight into energy, cyanobacteria expel oxygen as a byproduct and transform Earth's anaerobic atmosphere.
Great Oxidation Event
As cyanobacteria proliferate, they gradually increase Earth's oxygen levels, leading to the Great Oxidation Event about 2.4 billion years ago. This sends evolution into a tailspin as up to 90% of all species die.
Cyanobacteria live in diverse aquatic environments, from freshwater to marine, and extreme habitats like hot springs and hypersaline lakes. The earliest cyanobacteria enjoy warm, shallow waters with plenty of sunlight and nutrients.
Stromatolites are among the oldest known formations linked to these organisms. The layered structures give insight about early microbial life and significant changes in the atmosphere.
Red Tides and Brevetoxin
Some cyanobacteria such as Karenia brevis can form harmful algal blooms (HABs), also known as red tides due to the reddish-brown color they impart to the water. These blooms occur when cyanobacteria grow rapidly.
They consume available nutrients and creating dead zones in the water. During red tides, some cyanobacteria produce toxins, such as brevetoxin, which can poison marine life and humans. In 2018, Florida red tides cause fish kills and tourist decline.
Causes of Blooms
Cyanobacteria bloom is caused by various factors. These include increased nutrient loads from agricultural runoff, sewage and other human activities in mass industry.
Changes in water temperature, salinity, and light conditions also trigger blooms. More frequent and intense cyanobacteria explosions are expected in the future. Global warming is cited as a factor.
Nutrients most linked to runaway blooms are nitrogen and phosphorus. Nitrogen (N) is in all living organisms, mainly amino acids, thus proteins; in nucleic acids and energy transfer molecule adenosine triphosphate (ATP).
Phosphorus (P) interacts primarily through phosphates, compounds containing the phosphate ion, PO43−. Phosphates are integral to DNA, RNA, ATP and phospholipids, fortifying cellular structures.
These are two of the most important nutrients in fertilizers for agriculture, industry and backyard gardening. Cattle manure contains both and more, used for thousands of years for its plant vitalizing properties.
Facts About Cyanobacteria
Some cyanobacteria evolve symbiotic relationships with plants and fungi. These associations enable cyanobacteria to fix nitrogen into ammonia, making it available to hosts in exchange for carbohydrates. They increase nutrient uptake to plants, especially legumes.
Cyanobacteria are most prolific when environmental nitrogen and phosphorus content increases, for example in industrial leakage.
Cyanobacteria are considered a valuable source of bioproducts, including biofuels, pigments, and pharmaceuticals.
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