Limnology (2+1)

Unit 1- Limnology- An introduction

1.1.1 Introduction
Civilizations have depended on water bodies such as lakes, reservoirs, rivers and wetlands. Water is essential not only to sustain human life but also to support the activities that form the basis for thriving economics. Though the water resources are essential to human societies who could pollute and degrade and limiting their beneficial uses. Agriculture, mining, urban development and other activities can pose risks to freshwater bodies and hence steps have to be taken to reduce these risk factors.
Risk analysis requires knowledge of how human land use affects physical, chemical and biological characters of the aquatic systems. One of the critical areas required to understand how human actions and natural processes affect lakes, reservoirs, rivers and wetlands is the science called Limnology. It is a multidisciplinary science that integrates the basic sciences (Biology, Chemistry, Physics and Geology) in order to study inland waters as complex ecological systems.

Definition
The term Limnology is derived from Greek word; Limne means lake and logos means knowledge. Limnology is often regarded as a division of ecology or environmental science. It is however, defined as “the study of inland waters” (running and standing waters fresh and some times saline; natural or man made). This includes the study of lakes, ponds, rivers, reservoirs, swamps, streams, wet lands, bogs, marshes etc. Hence, it is commonly defined as that branch of science which deals with biological productivity of inland waters and with all the causal influences which determine it (Welch, 1963).
Biological productivity, as used in this definition, includes its qualitative and quantitative features and its actual and potential aspects. Under the term inland waters are included all kinds or types of water – running or standing; fresh, salt or other physicochemical composition which are wholly or almost completely included within the land masses. Causal influences involve various factors – physical, chemical, biological, meteorological etc which determine the character and quantity of biological production.

History
The term Limnology was coined by Francois-Alphonse Forel (1841 – 1912) who established the field with his studies on Lake Geneva. Interest in the discipline rapidly expanded and in 1922 August Thienemann (a German Zoologist) and Einar Naumann (a Swedish Botanist) co-founded the International Society of Limnology (SIL, for originally Societas Internalis Limnologiae). Forel’s original definition of limnology, oceanography of lakes was expanded to encompass the study of all inland waters.
Welch (1935) conceived the problem of “Biological productivity” as the central theme of Limnology. He defined Limnology as that branch of science which deals with all causal influences which determine it. According to Schwoerbel (1987), Limnology is the science of inland waters viewed as ecosystems together with their structures, materials and energy balance. Kiihnelt (1960) considered limnology as a sub set of ecology along with “Oceanography” (which is concerned with marine ecosystem) and “Epheirology” (which deals with terrestrial habitats). In short, Limnology is the study of all aquatic systems including lakes, wetlands, marshes, bogs, ponds, reservoirs, streams, rivers etc. with regard to their physical chemical and biological characteristics.
In addition to the above, certain other terms, like Hydrobiology, Freshwater Biology, Aquatic Biology, Aquatic Ecology etc, are sometimes loosely used as synonymous to the word 'Limnology'. But, most of these terms are names under which a diverse variety of subject matter is included and only a part of it is limnological in nature.