Abstract
Indiscriminate use of different pesticides in agriculture has increased over the years, especially in the developing countries. This influences the aquatic environment to a great extent. This also poses a great danger to freshwater organisms, including fish, which constitute a major share in the aquatic environment and contribute to the economy of the nation. Water pollution is posing intricate problems that need immediate redress. Organo-chlorine pesticides (OCPs) are a major contributor to aquatic pollution and are amongst the most serious global contaminants. In addition, organochlorine pesticides have a tendency to accumulate in aquatic biota; they also undergo food chain amplification. Lipophilic pollutants are chemically very stable and resistant to microbial, photochemical, chemical, and thermal degradation. The chemical stability of these compounds, their high lipid solubility, and their toxicity to human beings and animals has led government and researchers to feel concerned about their presence in the environment.
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Aquatic Ecosystem
An ecosystem in a water body where communities of various organisms depend on each other as well as on their environment is referred as aquatic ecosystem. Organisms which depend on water for their life activities such as feeding, breeding, shelter, etc. in order to survive are called as aquatic organisms. It is of three types namely freshwater, marine and estuarine. Freshwater covers only 8% of the earth and involves lakes, ponds and pools (lentic) and rivers and streams (lotic) habitats. Marine water bodies cover largest surface area and constitute oceans, seas, reefs, sea beds, intertidal zones, etc. Estuarine areas are those which experience the flux of both freshwater and marine water depending on tide and water currents. Animals living in these water bodies have adapted themselves according to their habitats. Estuaries are semi enclosed bodies of brackish water which is less salty than marine waters. Freshwater animals cannot survive in the saline environment of marine water bodies. Freshwater used for irrigation purposes in agricultural land often absorbs levels of salt that might harm freshwater organisms.
Aquatic ecosystem links human populations, land and wildlife through water. Man has shown keen interest in aquatic resources such as sea food, fisheries, fishing sport, swimming, observing natural beauty, etc. The relationship of man with his environment is essentially symbiotic and equilibrium should be maintained between the two. Rapid growth of human population, over-exploitation of natural resources and developments in agriculture and industry has contributed extensively to the presence of various pesticides in the aquatic environment. Time is perhaps not far when pure and clean water, particularly in densely populated and industrialized areas, may be inadequate for maintaining normal living conditions.
Key Terms in this Chapter
Pesticide Label: The guide that gives directions for safe and effective use of pesticide.
Carcinogenic: Having the potential to cause cancer.
Lipophilic Compounds: Compounds that have tendency to get dissolved in lipids or fats.
Organochlorine Pesticides: Chlorinated hydrocarbons that are used extensively in agriculture and vector control.
Mutagenic: Having the potential to cause changes at genetic level.
Aquatic Biota: Organisms living in or depending on aquatic environment.