What is Algae


What is Algae?

Algae are used by man in a great many ways. Because many species are aquatic and microscopic, they are cultured in clear tanks or ponds and either harvested or used to treat effluents pumped through the ponds.

Food Stuff: Algaculture on a large scale is an important type of aquaculture today. Certain species are edible like red dulse, which is dried and marketed in Ireland. It is eaten raw, fresh or dried, or cooked like spinach. Porphyra, commonly known as purple laver, is also collected and used as “laver bread” and jelly in UK. Chondrus crispus, common name: Irish moss, is also used as carrageen for the stiffening of milk and dairy products, such as ice-cream. Ulva lactuca, common name: sea lettuce, is used locally in Scotland where it is added to soups or used in salads.

Uses of Algae

Algae Used as a Fertilizer:

For centuries seaweed has been used as manure. There are also commercial uses of algae as agar. Maerl is harvested as fertilizer of organic gardening. Chemical analysis of maerl showed that it contained 32.1% CaCO 3 and 3.1% MgCO 3 (dry weight).

Algae uses as an Energy Source:

Algae can be used to make biodiesel, and by some estimates can produce vastly superior amounts of oil, compared to terrestrial crops grown for the same purpose. Because algae grown to produce biodiesel does not need to meet the requirements of a food crop, it is much cheaper to produce. Also, it does not need fresh water or fertilizer. Algae like Chlamydomonas reinhardtii (a green- algae) can be grown to produce hydrogen. Algae can be grown to produce biomass, which can be burned to produce heat and electricity.

Algae used in Pollution Control

Algae are used in wastewater treatment facilities, reducing the need for more dangerous chemicals. Algae can be used to capture fertilizers in runoff from farms and if this alga is then harvested, it itself can be used as fertilizer. Algae bioreactors are used by some power plants to reduce CO 2 emissions. The CO 2 can be pumped into a pond, or some kind of tank, on which the algae feed. Alternatively, the bioreactor can be installed directly on top of a smokestack.

Nutritional Value of Algae

Algae is commercially cultivated as a nutritional supplement. One of the most popular micro algal species is Spirulina, which is a Cyanobacteria (known as blue-green algae). Other algal species cultivated for their nutritional value include; Chlorella (green algae), and Dunaliella (Dunaliella salina), which is high in beta-carotene and is used in vitamin C supplements. Algae is sometimes also used as a food, as in the Chinese vegetable known as fatchoy (which is actually a cyanobacterium). The oil from some algae has high levels of unsaturated fatty acids. Arachidonic acid (a polyunsaturated fatty acid), is very high in Parietochloris incisa, (a green alga) where it reaches up to 47% of the triglyceride pool.

Dyes & Pigments produced from algae

The natural pigments produced by algae can be used as an alternative to chemical dyes and coloring agents. Many of the paper products used today are not recyclable because of the chemical inks that they use but inks made from algae are much easier to break down. There is also much interest in the food industry into replacing the coloring agents that are currently used with coloring derived from algal pigments.

  • Blue-Green Algae (Moneran): They contain a blue pigment phycocyanin in addition to chlorophyll and other pigments. Only asexual reproduction occurs among them. They contaminate drinking water, causing very disagreeable odor and taste. They bring about the reddish color of the Red Sea, used as soil fertilizer. Some species thrive in the digestive tract of human without causing ill effects. Some members – Gloeocapsa and Nostoc have formed a partnership with fungi, making up the separate group of organism known as lichens.
  • Euglena : Found in stagnant ponds, swimming pools, aquariums, water become greenish, unpleasant flavor.
  • Green Algae: Self-food maker, add O 2 to water available for fish and other organisms, also serve food for these creatures. They often cause water pollution in lakes, tanks etc. may cause unpleasant flavors and odors, their respiration may lower the O 2 content of the water. So the fish in this area may die of suffocation (CuSO 4 can eradicate unwanted green algae). Spirogyra – B.G. Algae
  • Brown Algae : (brown pigment fucoxanthin): They are marine plants and are the source of food for fish and others- It is the major source of Alginic acid. By removing from sea can be used as cattle feed. Some species yield Iodine, some make excellent fertilizers. Kelps – B. Algae include the largest member of the group. Macyosist Pyrifera- giant kelp, longest plant of world (30 mt. or more). Gulfweed or sargassum – B. Algae in Saragossa sea (West Indies to Azores).
  • Diatoms (yellowish green to yellowish brown): They have cell-wall, contain silica and are harmless to man. They often make up the bulk of the plankton as sea animal food. It serves as filter and clarifies many liquids. They are excellent insulating material for boilers, blast furnaces refrigerators and are used as a milk abrasive in polishes and scouring powders
  • Red Algae : (red, brown and violet): They are multicellular and generally used as food for sea animals and fish, as food for human (in Europe and Far East). Irish moss is also used for curing leather and for shoe polish and creams and shampoos. Ceylon moss yields a gelatinous material known as agar-agar, observe a great deal of water, used by researchers as growth material for bacteria, also serves to thicken soups and broths, as a sizing material for textiles, as a mild laxative, to provide body for puddings, pastries, ice-creams, etc. Some algae secrete lime so they have helped to build coral reefs (dating back to Ordovician times).

Ecological Role of Algae

Although often inconspicuous, fungi occur in every environment on Earth and play very important roles in most ecosystems. Along with bacteria, fungi are the major decomposers in most terrestrial and some aquatic ecosystems, and therefore play a critical role in biogeochemical cycles and in many food webs.

Many fungi are important as partners in symbiotic relationships with other organisms, as mutualists, parasites, or commensalism, as well as in symbiotic relationships that do not fall neatly into any of these categories. One of the most critically important of these relationships is various types of mycorrhiza, which is a kind of mutualistic relationship between fungi and plants, in which the plant’s roots are closely associated with fungal hyphae and other structures. The plant donates to the fungus sugars and other carbohydrates that it manufactures from photosynthesis, while the fungus donates water and mineral nutrients that the hyphal network is able to find much more efficiently than the plant roots alone can, particularly phosphorus.

The fungi also protect against diseases and pathogens and provide other benefits to the plant. Recently, plants have been found to use mycorrhizas to deliver carbohydrates and other nutrients to other plants in the same community and in some cases can make plant species that would.

Lichens are formed by a symbiotic relationship between algae or cyanobacteria and fungi, in which individual photobiont cells are embedded in a complex of fungal tissues. As in mycorrhizas, the photobiont provides sugars and other carbohydrates while the fungus provides minerals and water. The functions of both symbiotic organisms are so closely intertwined that they function almost as a single organism.

Certain insects also engage in mutualistic relationships with various types of fungi. Several groups of ants cultivate various fungi in the Agaricales as their primary food source, while ambrosia beetles cultivate various kinds of fungi in the bark of trees that they infest. Some fungi are parasites of plants, animals (including humans), and even other fungi. Pathogenic fungi are responsible for numerous diseases, such as athlete’s foot and ringworm in humans and Dutch elm disease in plants. Some fungi are predators of nematodes, which they capture using an array of devices such as constricting rings or adhesive nets.

Some fungi are parasites of plants, animals (including humans), and even other fungi. Pathogenic fungi are responsible for numerous diseases, such as athlete’s foot and ringworm in humans and Dutch elm disease in plants. Some fungi are predators of nematodes, which they capture using an array of devices such as constricting rings or adhesive nets.


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