Within the Hydrosphere, Fishes and Fresh waters: Availability and Sustainability in the Ecosystem:- Avoaja, Diane A.

ABSTRACT

THE HYDROSPHERE: The hydrosphere refers to the water on or surrounding the surface of the globe, as distinguished from those of the lithosphere (the solid upper crust of the earth), and the atmosphere (the air surrounding the earth). More specifically, the hydrosphere includes the region that has all the earth's liquid water, frozen and floating ice, water in the upper layer of soil, and the small amounts of water vapour in the earth's atmosphere. The earth's water has six major reservoirs in which water resides. These include the oceans; the atmosphere; surface water (including water in lakes, streams, rivers, and water held in the soil); ground water; snow; and ice. My attention is focused on the 3rd, i.e. surface water (freshwaters/inland waters). Fig. 1 shows the composition of the earth's water supply. Ocean /salt water occupies 97.5% while freshwater/inland water occupies only 2.5%. The quality of natural water in the various reservoirs depends on a number of interrelated factors. These factors include geology, climate, topography, biological processes, land use and the time the water has been in residence.