Question

explain eutrophication and biological magnification, with examples

Answer 1

look the pic for the answer of eutrophication

Answer 2

Answer:

Eutrophication

It is referred to the natural ageing process of a lake as a result of nutrient enrichment caused by the overflow of nutrients such as fertilizers, animal wastes and sewage from land leading to an increased fertility of the lake. Consequently, there is a huge increase in the primary productivity of the ecosystem bringing about an increased growth of algae, hence in algal blooms. After sometime, the decomposition of these algae reduces oxygen supply, resulting in the death of aquatic animal life.

Biological magnification

Pesticides are used on a large scale to protect crops from various diseases and pests. When these pesticides enter the soil, they are absorbed by plant parts with minerals and water from the soil. These chemicals can enter water sources as a result of rains, furthermore into the bodies of aquatic animals and plants, hence into the food chain. As these chemicals cannot be disintegrated, at each of the tropic levels, they keep getting accumulated, wherein most of the accumulation occurs at the top carnivore’s level. This is termed as biological magnification where there is increase in the concentration of harmful pollutants with each increasing tropic level.

For instance, high DDT concentration in a pond saw the producers (phytoplankton) to have a DDT concentration of 0.04 ppm. As these phytoplankton were consumed by zooplankton – the consumers, the concentration of DDT in the bodies of zooplankton was noted to be 0.23 ppm. When this in turn is consumed by small fish, more of DDT gets collected in their bodies. Consequently, the large fish (top carnivore) feeding on different small fish tend to have the maximum concentration of DDT.