Limnology

Limnology

The term “limnology” was first used in 1892 by F.A. Forel, a professor at the University of Lausanne, Switzerland. F.A. Forel is called “Father of Limnology”

Greek term “limnos\limne” means marsh or lakes or pond; so limnology means study of lakes. But actually it deals with inland waters. Limnology deals with geology, chemistry, physics, and biology of inland waters. The limnological study of inland waters is ecological in nature.

Limnology is that branch of science which deals with biological productivity of inland waters and with all causal factors which determine it. (Welch, P.S. 1952)

Limnology is the study of biological production of inland waters and all causal factors which determine biological production.

There are three main parts in Limnology

·         Physical Limnology

·         Chemical Limnology

·         Biological Limnology

Biological Productivity

Biological productivity is the production of both plants and animal of inland waters. Biological productivity includes its qualitative and quantitative features and its actual and potential aspects. Production of plankton, fishes, and crustaceans are most important.

Inland Waters

Inland waters mean inland water bodies. Inland waters include all kinds or types of inland water bodies which are running (Lotic) or standing (Lentic) mainly freshwater (salinity <0.5%) or it may be salt or brackish water, which are completely or almost completely included within the land masses.

Example: Ponds, Lakes, Marshes, Canals, Streams and Rivers, Estuaries, Drains, Rice fields with water, Ditches, Water reservoir, Cistern (Chovascha) etc.

Causal Factors

Causal factors which mean those factors or influences or conditions which determine the biological productivity of inland waters.

Casual factors are mainly of five kinds:

1. Physical factors –Light, Temperature, Form of basin, Turbidity, Water movement, Current, Mixing, Transparency etc.
2. Chemical factors – Dissolved gases D.O, free CO2 other gases, dissolved solids (nutrients) Nitrogen, Phosphorus, Calcium, Magnesium, Iron, Sodium, Potassium, etc, Alkalinity, Hardness, Salinity etc.
3. Biological factors – Parasitism, Predation, Grazing (a kind of predation), Competition, Antibiosis etc.
4. Meteorological factors – Rainfall, Snowfall, Sunshine period, Air temperature, Lightning and Thunder, Storm, Season etc.
5. Geological factors – Geographical position, Soil types of basin, Origin of lakes basins etc.

      

Scope of Limnology

Limnological knowledge and limnologist are needed in different fields and works of fisheries and related to fisheries as follows:

1.      Aquaculture – Limnological knowledge is prerequisite and essential for successful aquaculture.

2.      Fisheries Extension – Fisheries extension work is not possible without limnology.

3.      Fisheries Development and Planning – For developing in the field of fisheries and for development planning in fisheries, limnological knowledge and limnologists are essential,

4.      Water Development and Planning – Limnological knowledge is essential for success in the field of water development and planning.

5.      Reclamation and Pollution Control of Inland Waters – Reclamation of derelict water bodies is not possible without limnological knowledge. To understand nature and degree of pollution in inland water bodies and to control and remove aquatic pollution limnological knowledge and limnologist are essential. In case of fish culture maximum and sustainable fish production of a pond or lake can be achieved by careful application of limnological knowledge and information of that particular pond or lake. Without limnological knowledge successful planning of water development and management projects are not possible.