Fresh Water Environment and Man Made Ecosystems

The fresh water environment is characterized by its low concentration of salt and mineral ions. The fresh water ecosystem consists of lakes, ponds, streams and rivers. Fresh water lakes may be classified under two categories:

i) Lakes and Ponds Ecosystems

Both lakes and ponds are characterised by stagnant fresh water bodies and occur practically in every biome. They also vary in their size from less than a hectare to thousands of hectares; like the Caspian Sea, Lake Superior, Lake Victoria (Africa), Lake Baikal, Lake Balkash (Central Asia), Dal and Wular Lakes (Kashmir Valley), and Sambhar Lake (Rajasthan).

The shallow lakes have a rich accumulation of organic compounds. Consequently, they are called Eutrophic Lakes with rich circulation of nutrients such as phosphate. On the other hand, lakes with steep and rocky sides are poor in circulating nutrients such as phosphate, and are called Oligotrophic Lakes.

ii) Streams and Rivers

Streams and rivers are free wing fresh water-bodies. They differ from each other in volume of fresh water they carry, speed of flow, oxygen content, temperature, pH and other numerous chemical and physical conditions.

The rivers, especially big ones, such as Nile, Amaz on, Yantze-Kiang, Mississippi-Missouri, Ganga, Brahmaputra, Indus, etc. Originate from the glaciers, springs or lakes. Their water glows in rapid currents. They have generally less floating population of planktons. In the lower course, the water becomes muddy and an abundance of phytoplankton and zooplankton is found.

Most of the rivers of the developing countries are becoming increasingly polluted. According to the experts the sacred Ganga is now a deadly source of cancer. A study conducted by the National Cancer Registry Programme under the Indian Council of Medical Research, throws up shocking dings. According to this study the incidence of cancer, especially gall-bladder are the second highest in Ganga basin in the world. The worst affected areas are east Uttar Pradesh, the flood plains of Bihar and West Bengal. The cases of Kidneys, food- pipe, prostate, liver urinary and skin cancer are also significantly high in the areas drained by the Ganga. Despite spending an estimated ` 2,000 crore under Ganga Action Plans I and II, the sewage treatment capacity and other pollution abatement infrastructure along the Ganga remain woefully inadequate. The new Mission Clean Ganga approved by the National Ganga River Basin Authority mandates an investment of ` 15,000 crore over the next 10 years to clean the river. Failure to full this goal would not only create the World’s worst health disaster zone, but also spike India’s industrial and economic growth.

Aquatic Succession

The aquatic ecosystems vary from open oceans to small ponds. In these systems conditions of salinity, depth and temperature varies from one another. The lakes and ponds succession is known as aquatic succession. A lake experiences successional stages as it fills with nutrients and sediments and as aquatic plants take root and grow, capturing more sediment and adding organic debris to the system. This gradual enrichment of water bodies is known as eutrophication. For example, in moist climates, a floating mat of vegetation grows outward from the shore to form a bog. In this condition, marsh plants become established, and partially decomposed organic material accumulates in the basin, with additional vegetation bordering the remaining lake surface. A meadow may form as water is displaced by the peat bog; willow trees follow, and perhaps wood trees; and eventually the lake may evolve into a forest community.

Man Made Ecosystems

Man-made ecosystems include villages, towns, cities, fishery-tanks, aquarium, social forestry, orchards, and agricultural land. The agro-ecosystems are the most important of the man made ecosystems. In the agricultural ecosystems man sows selected crops and keeps a few livestock. These ecosystems are highly et but are poor in diversity sustainability. In fact, man made ecosystems are more vulnerable to droughts, floods, pests, diseases and pathogens.

Fire Ecology

Fire ecology recognizes fire as a dynamic ingredient in community succession. Controlled, widely regarded as a wise forest management, secure plant reproduction and prevent the accumulation of forest litter and brush.

Successional stages of ecosystems may be interrupted by fire. It is estimated that about one-fourth of Earth’s forest area experiences fire each year. Over the past 50 years, the ecology has been the subject of much scientific research and experimentation. Today, fire is recognized as a natural component of most ecosystems and not the enemy of nature it once was popularly considered. In fact, in many forests, undergrowth is purposely burned in controlled ‘cool fires’ to remove fuel that could enable a catastrophic and destructive ‘hot fires’. In contrast, when fire prevention strategies are rigidly followed, they can lead to abundant undergrowth accumulation, which allows total destruction of a forest by a major fire.