Several studies appeared in the past regarding the effects of heavy metal pollution on aquatic organisms

Several studies appeared in the past regarding the effects of heavy metal pollution on aquatic organisms, they pertain to mortality studies. The reports on the damage caused to different internal organs and the changes in various physiological and biochemical process and causes of death after exposure to aquatic poisons are relatively few. In the quest of increasing fish production, there has been considerable ignorance to water quality.
The ground water contamination particularly by the industrial effluents including heavy Metals and their found in food chain has been of major concern as it is posing a serious threat to aquatic ecosystem and cultures including fishes and prawns. Heavy metal has been man’s worst endeavor in his attempt to augment industrial development. Today, the heavy metals are termed as ‘devils in disguise’ and the economic reason impels us to keep these using. Heavy metals are bio accumulative and relatively stable as well as toxic/carcinogenic and therefore, require close watching and monitoring. The values of heavy metals reported in water are higher than the permissible health values as given by EPA. In India cadmium, lead, mercury, cobalt etc., have been very common heavy metals, their residues have been reported in water resources.
Today aquaculture has become the primary diet and there have been attempts to devise ways to enhance fish and prawn production. The requirements of hour are to rationalize the use of industrial waste and effluents on one hand and other side to reduce their effects with other biotic components including the fishes and other aquatic organisms. Apart from acute and chronic toxicity, the heavy metals in water have proved various dangerous and also harmful because of their bioaccumulation and biomagnifications and their impact on tissue degeneration. Beside these chemicals and toxic substance are also established to induce reproductive functions, thus influencing growth, survival and reproductive potential of animals/ fishes. Loss of immunity, necrosis, inflammation, and edema are many other pathological conditions. Such studies in fishes have been limited to study of certain morphological and histopathological alterations in gills, liver and kidneys and some biochemical alterations in blood and various tissues of muscle, gills, liver, kidney and brain. These studies so far have been inconclusive in determining the ultimate fasten of these chemical hazards in fish tissues. The detailed study of various chemical and toxic materials contaminated induced biochemical-physiological aberrations in fishes thus could be of vital role of importance, both to the humans and sustained aquaculture.
Chromic effect of copper toxicity adversely affected the growth and all the physiological activity including reproduction in fish. Denature of mucus on the gills of fishes exposed to copper leads to respiratory process. Fishes exposed to mercury exhibit neurological damage and histopathological changes in the visceral organs and gills. The body size determines the susceptibility of fish to a variety of toxicants. Trace quantities of certain elements exert either positive of negative influence on plant, animal and human physiology. Metals are no degradable in nature, forming stable complexes and cause undesirable effects, when present in low concentrations trace metal can retard or induce abnormal growth when their concentrations exceed critical limits.
All metals are strongly chaleophilic (affinity for sulphur) in their mineralogy and chemistry and their affinity for sculpture is greater than oxygen. Hence they attack the sulphur bonds present in the enzymes and thus inhibit various metabolic activities that are taking place in the organism. They also exert toxic effect by combining with one or more reactive groups essential for normal physiological function. Heavy metal levels in plankton are directly related to metal concentration in water. Fishes in river Subarnarekha has a considerable amount of heavy metals. Mercury in found to be most toxic, its level was studied periodically in all rivers and water bodies since the occurrence of Minamata disease in Japan.
AQUATIC ECOSYSTEM AND ITS POTENTIAL A CASE STUDY
INTRODUCTION
Of the earth total water volume of about 1386 million km3 about 96.5% is saline ocean water that is unsuitable for human as well as plant use as such. Of the remaining 3.5%, is considered fresh water of the many major part is stored in the form of ice and glaciers. Only one present of the earth’s water is cycled in hydrological cycled (Gupta et al.,2000)water is on important ecological factor in the life organism. It possess unique property such as universal solvent, for practically all mineral, raw material for photosynthesis maintenance of better physiological condition, and play an important role in fertilization, pollination and dissemination. Large numbers of animals and plants use two kind of habitat, viz terrestrial and aquatic at difference limes of the cycle and plants for different sources, hence it become very difficult to priorities the habitat. Undisputedly aquatic ecosystem including wetlands and estuarine occurs in all climate zones and are among the most productive habitat with net primary production being as high as that of tropical rain forest (Brij Gopal, 1990).
Most of the water habitats are providing raw material for life supporting system viz fodder for livestock, food for human consumption, and other material for varied utility. Due to rapid growth of population, demand for water has increased. The availability of water for domestic use per capita has reduced drastically. Main reasons for this are population explosion, harvesting more water for agriculture activities, unplanned and un-eco-friendly growth of industries and so on. All these are polluting the water, a vital element for survival.
Wetlands covers very wide range of habitates and occur in all climatic zones. Wetlands (except temperate peatbogs) are among the most productive habitat with net primary production being as high as that of tropical rain forest (Gopal, 1990) and support very high biological diversity. Other than this wetlands perform several ecological functions depending upon their position, nature and biological characteristics. These have been discussed in a number of publications (Sather and Smith 1984; Sather et.al, 1990; and Gopal, 1994). Water bodies dominated by macrophytes including submerged plants through tall grass and sedges are invariably used as grazing ground by domestic and well as wild herbivores and various species of waterfowls. Macrophytes not only provide food but also create nuisance disturbing aquatic sports, navigation, and blockage of the water channels due to tremendous growth potential. From the earlier studied of Gortner (1938), Nelson and Palmer (1938) Baily (1965), and Ho (1979) it has established that macrophytes have nutritional potential. Presents study is also an effort in the same direction to generate data base for nutritive value for dominating macrophyts in water bodies around Agra and to categories and nutritive potential of this aquatic flora.
FRESH WATER POLLUTION IN INDIA: AN EMERGING PROBLEM
With a population growth rate of about 2% per annum and an economic growth rate of about 4 % per annum. India is likely to face increasing environment problems in genial and water pollution in particular in the future.
Water is important for the survival of any form of life. On an average normally a human being consumes about 5 litres of water each and every day. Which accounts for about 70% of the weight of a human body. About 80 % of the earth’s surface i.e. 80 % of total 50,000 million hectares in area is covered by total water. Out of the estimated 1,011 million km3 of the total water present on earth, only 33,400 m3 of water in available for drinking purpose, agriculture, domestic and industrial consumption. The rest of the water is locked up in Oceans as salt water, polar ice-caps and glaciers and underground (Dara 1993). Owing to increasing industrializing on one hand and exploding population on the other, the demands of water resource have been increasing tremendously. More over, considerable part of the limited quantity of water is polluted by anthropogenic activity of human beings, municipal sewage, industrial wastes and a wide array of synthetic chemicals, etc.
The environment of organisms living in fresh water consists of a number a habitat factors such as the temperature, the amount of sunlight penetrating the water, its density and its chemical constitution all of which influence there distribution, and which interest to cause fluctuations in, the size of populations, which limit populations with in a community as well as their ability to spread to other.
To this must now add man who is one of the most potent factors in altering the structure and nature of a community. Pollution that can be rather widely applied to include substance introduced into an environment which are potentially harmful to or which interfere with man’s own use of his environment.
Recent realization of pollution hazard in aquatic system give impetus to the prodigious amount of research of aquatic fauna both in lentic and lotic habitats. The confluence of industrial effluents in the near by river system conglomerates the entire aquatic biota and undergoes self-purification during its course depending on the intensity of its polluted contents.
The rivers form a part and parcel of the human society. For the people of India, the rivers are not a mere means of transport, recreation, power generation and a treasuer house of natural resources, but something divine and holy, they are sentimentally attached to the rivers and they do worship them. The riverside assume a lot of significance during

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