Water covers about three-quarters of the earth’s surface and it is essential for all known forms of life. Water is a habitat for a variety of plants and animals which have special adaptations to survive in their habitats. Some of the characteristics that control the quality of water are the turbidity of water, pH of water and different types of plants and animals and their density.
Turbidity is the measure of the relative clarity of a liquid. Turbidity of the water body determines the depth to which light can penetrate and thus affects the distribution and photosynthesis of phytoplankton and macrophytes. The pH is a measure of the relative amount of free hydrogen and hydroxyl ions in an aqueous solution. Solutions with a pH less than 7 are said to be acidic and with a pH greater than 7 are basic. The pH of pure water is 7 at 25°C. A productive water body has high nutrient concentrations, and has a very high density of phytoplankton per unit area. These water bodies have high amounts of nutrients and dissolved oxygen and bear large number of organisms at different trophic levels. The status of health of a water body can be determined by analyzing water samples for the number and type of organisms present in it at a given time.
This video explains how to study different water bodies for pH, clarity and presence of any living organisms.