|Blue Green algae
Blue-green algae or Cyanobacteria are microscopic cells that grow naturally in fresh and salt waters. They are a type of bacteria, but in some ways act like plants by using sunlight to manufacture carbohydrates from carbon dioxide and water, a process know as photosynthesis. In doing so, they release oxygen. They grow in dams, rivers, creeks, reservoirs, lakes and even hot springs.
When blue-green algae bloom, that is, grow to large numbers, they can form thick accumulations on the surface of the water. These accumulations are commonly known as scums. Blue-green algal scums form when large numbers of the algae float to the water surface using vesicles within their cells that they inflate with gas. Coming close to the surface enables them to gain maximum sunlight.
|Microcystis, (Anacystis) is probably the most common toxic algae occuring in farm dams, usually form greenish-yellow bubbly masses in still or nearly still water. The plant cells are arranged like a small hair net. A blue green algae has numerous small cells crowded within a gelatinous matrix, forming a colony which may be ovate (like an egg) or an open meshwork. Microcystis is found free floating in lakes, reservoirs and sometimes in slow flowing rivers. Colour ranges from blue-green or yellowish brown. The colonies are usually globular. A hint of red can often be seen. It is a common cause of algal blooms and can secrete chemicals that inhibit other algae. It can also produce a polypeptide which is toxic to animals after drinking contaminated water. It has also been implicated in human illnesses including necrosis of the liver (after drinking) and severe dermatitis (after contact),etc. There are 40 reported species.|
|Filamentous also known as "pond moss" or "pond scum" these threadlike algae often occur in huge greenish masses floating upon the waters' surface.They can form dense mats in static water or long, rope-like strands in flowing water. Its filaments consist of series of cells being joined end to end giving a thread-like appearance. This form begins growing on the bottom or substrate and then lifts to the surface as buoyancy grows due to its production of oxygen. This form of algae may seem cottony, slimy, or coarse in texture.|