Cyanobacteria or blue-green algae are a significant group of entities in the food chain found across the globe. These are simply a kind of bacteria, however, like plants, they too use sunlight in order to grow. Most of them are found thriving in association with other kinds of algae. These bitsy entities are collectively referred to as plankton. 

These cyanobacteria are found inhabiting marine water, freshwater and slightly salty environments. Under appropriate conditions, cyanobacteria can rapidly grow and hence the characteristic algal bloom; for the formation of this bloom, environmental factors such as temperature, light and nutrients are conducive.The main biochemical or physiological cyanobacteria characteristics which is a striking one amongst other prokaryotes has to be the possession of dual photosystem allowing the utilization of water as a photoreductant with the resultant release of oxygen.

Organization and structure 

The organization and the structure of cyanobacteria are examined under an electron or light microscope. Its basic morphology includes unicellular, colonial and it exists even in multicellular filamentous forms.

For instance, the unicellular forms present in the order Chroococcales, have cells of the nature ovoid, spherical or cylindrical. It takes place individually when the daughter cells detach after being reproduced through the process of binary fission. Its cells can aggregate in irregular colonies which are held together by the slimy matrix produced when colonies are growing. Due to more or less series of cell divisions along with secretions of the sheath, there can be seen colonies that are more ordered. 

Repeated cell divisions cause filamentous morphology seen in a single plane at 90° to the main axis of the filament. A trichome is a multicellular structure comprising a chain of cells which could be coiled or straight. The size and shape of the cell varies greatly amongst the filamentous cyanobacteria. 

The species present in the order Oscillatoriales with unbranched and unseriated trichomes are made of identical cells. The vegetative cells can be differentiated into akinetes and heterocysts. Both akinetes and heterocysts can be seen in the order Stigonematales, usually multiseriated with a true branching. 

Algal blooms 

Algal blooms can be apparent as purple, red, green or rust-shaded. At times, these resemble spilled paint. Blooms could be seen on the surface of water, below the surface or mixed all through the water column. With time the toxins are diluted and gradually disintegrate and vanish. 

Even though these cyanobacteria naturally occur, an elevation in the availability of nutrients can aggravate the duration, extent and intensity of these blooms. Blooms are also inclusive of other factors such as reduced flow of water, warmer temperatures, circulation and deprivation of animals which consume algae. 

The blue-green algal blooms are normally identified by its appearance of a scum on the surface of water or/and bluish-green stained water. Several times, it comes with a foul odor. Having said that, these algal blooms may also occur in water appearing clear. More likely, the cyanobacteria algal blooms can be prevalent in ponds and lakes wherein water is less likely to get blended with and dispersed from waves and wind. This was a brief overview of cyanobacteria. Explore more related topics such as nutrient cycling to better understand concepts on cyanobacteria. Alternatively, subscribe to BYJU’S YouTube Channel for relevant information.