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Blue green algae 3


Occurence



Blue green algae is also known as Cynobacteria.

Cyanobacteria have the distinction of being the oldest known fossils, more than 3.5 billion years old, in fact! It may surprise you then to know that the cyanobacteria are still around; they are one of the largest and most important groups of bacteria on earth.

Since they are photosynthetic and aquatic, cyanobacteria are often called "blue-green algae" !!

Blue Green Algae or Cyanobacteria can be found in almost every conceivable environment, from oceans to fresh water, in rivers, lakes, damp soil, tree trunks, hot springs and snow. In other words they are able to survive in hostile conditions.

Characteristics

Blue Green algae are bacteria. They can vary considerably in shape, colour and size.

They are very small organisms and can be seen with the aid of a microscope as single cells, accumulations of cells (colonies) or filaments of cells (trichomes).



Certain types of blue-green algae have tiny gas vesicles in their cells, allowing them to float to the surface or sink to the bottom in response to changing light and nutrient availability.



This buoyancy-regulating mechanism gives the blue-green algae a competitive advantage in obtaining light and nutrients.

Wow! Smart thinking!

Blue Green Algae get their name from the bluish pigment phycocyanin which they use to capture light for photosynthesis. Photosynthesis in cyanobacteria generally uses water as an electron donor and produces oxygen as a by-product, though some may also use hydrogen sulfide as occurs among other photosynthetic bacteria.



Carbon dioxide is reduced to form carbohydrates via the Calvin cycle. In most forms the photosynthetic machinery is embedded into folds of the cell membrane, called thylakoids. They are photoautotrophs.

The large amounts of oxygen in the atmosphere are considered to have been first created by the activities of ancient cyanobacteria.Life on earth has been possible thanks to the Blue Green algae.

Cyanobacteria show gliding motility - movement of cells over surfaces without the aid of flagella. The molecular mechanism by which most bacteria propel themselves through liquid media by means of rotating flagella is relatively well understood.



Gliding motility is a trait common to many bacteria, yet the mechanism of gliding motility is unknown. The gliding motility apparatus which propels the cells involves a complex of proteins, yet the actual nature of the "motor" and how the components interact is not understood.

Favorable Conditions

Species of blue-green algae may dominate and increase excessively in water when the:

* nutrient levels, particularly phosphorus and nitrogen are sufficient to support the population growth

*water is still and turbulence is low (lack of mixing)

* weather patterns are stable for a long time

* weather is warm (although blooms can occur in cooler weather too).



Algal Blooms



Water affected by blue-green algal blooms often is so strongly colored that it can develop a paint-like appearance



Bloom' is a common term used to describe an increase in the number of algal cells to a point where they can discolour the water, form scums, produce unpleasant tastes and odours, affect shellfish and fish populations or otherwise create a nuisance and seriously reduce the water quality.

Blue-green algal blooms often persist for several weeks, sometimes months, depending mainly on the weather or flow conditions. Cooler, windy weather or increased flow may reduce or prevent blooms from occurring.



As the bloom dies, the cells tend to become 'leaky'. If the bloom contains species that produce toxins, these will be released into the surrounding water.



Once released, some toxins may persist for more than three months before sunlight and the natural population of bacteria in the water degrade them.



Health Hazards

Some blue-green algae produce toxins that could pose a health risk to people and animals when they are exposed to them in large enough quantities.



Health effects could occur when surface scums or water containing high levels of blue-green algal toxins are swallowed, through contact with the skin or when airborne droplets containingtoxins are inhaled while swimming, bathing or showering.

Consuming water containing high levels of blue-green algal toxins has been associated with effects on the liver and on the nervous system in laboratory animals, pets, livestock and people.



Livestock and pet deaths have occurred when animals consumed very large amounts of accumulated algal scum from along shorelines.

Direct contact or breathing airborne droplets containing high levels of blue-green algal toxins during swimming or showering can cause irritation of the skin, eyes, nose and throat and inflammation in the respiratory tract.



Benefits



Many Proterozoic oil deposits are attributed to the activity of cyanobacteria. They are also important providers of nitrogen fertilizer in the cultivation of rice and beans.



The cyanobacteria have also been tremendously important in shaping the course of evolution and ecological change throughout earth's history.



The oxygen atmosphere that we depend on was generated by numerous cyanobacteria during the Archaean and Proterozoic Eras. Before that time, the atmosphere had a very different chemistry, unsuitable for life as we know it today.

The other great contribution of the cyanobacteria is the origin of plants. The chloroplast with which plants make food for themselves is actually a cyanobacterium living within the plant's cells.

Sometime in the late Proterozoic, or in the early Cambrian, cyanobacteria began to take up residence within certain eukaryote cells, making food for the eukaryote host in return for a home. This event is known as endosymbiosis, and is also the origin of the eukaryotic mitochondrion.

So Blue Green Algae has been around for a long long time.It is now we are awakening to its contribution to life on earth.

It may sound presumptious to say , Long live Blue Green algae!
It is sure to be around when you and I are long gone.
Mon November 01 2010 09:17:27 PM by Aathmika cyanobacteria  |  Green Algae  |  blue green algae 1761 views

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