Impacts of deforestation
Deforestation: Deforestation means clearing of forests. Forests are cleared to meet increasing demands of land and raw materials such as for wood and agriculture. With today's modern technology, the forests are being cleared at a rate that they cannot be replaced. With forests being cleared not only will wildlife lose their habitat, it also causes other harmful effects.

Effects:

soil erosion:

When the trees are removed, the topsoil is exposed to rain and wind. Without the roots to hold soil together, the topsoil which is the most fertile layer is vulnerable to rain. It will get washed away or eroded during heavy rain, which causes soil erosion.

flooding:

When the soil get washed into the river, eroded soil causes water level to rise, increasing the chances of flooding.

desertification:
Sunlight now falls directly onto the soil. Water beneath evaporate rapidly, causing the soil to become hard and barren. Plants can no longer grow and organisms that feed on these plants will die off. Consequently, habitats are lost, species of organisms become extinct.

climate change:
Rainwater is retained and absorbed by roots of trees which is lost as water vapour during transpiration. This water vapour eventually falls as rain after condensation. Without the presence of trees, rainfall will decrease and causes the land to become warm and dry, thus annual rainfall decrease.

Impacts of over-fishing
As human population increases, the demand of fish also increases. Some species of fish have been caught in large number which cause the fish population to decrease and thus affecting the balance in the environment. With the advancement of fishing gear, marine life are caught indiscriminately. Marine life such as turtles and dolphins are caught unintentionally which are then dumped back into the sea, but they often die.

Other types of overfishing:
1)Trawlers drag large fish nets along the bottom of the sea, many unwanted species are trapped in the process.

2)Dredges scrape the seabed destroying coral reefs and other organisms that live on the seabed.

3)Cyanide fishing uses poison or dynamite to stun the fish but kills corals and other reefs organisms. The stunned fish are sold as pets.

Effects:
If over fishing is not controlled, this will lead to the extinction of a particular species as they are caught faster than they can be replaced. Fishes are unable to have a chance to grow and reproduce, therefore populations drop.

Impacts of entrophication
Overuse of chemical fertilisers containing nitrates and phosphates which are used to increase crop yield may cause water pollution.

Fertilisers:
contain nitrates and phosphates are used to increase yield of crops.These fertilisers are not absorbed immediately and can be washed into water bodies.This results in algae and water plants getting the nutrients instead."algae bloom" the rapid multiplication of algae,will block out sunlight that reaches submerged plants.These submerged plants die,and organisms feeding on the plants will die.Bacteria growth is rapid and dissolved oxygen is used up.Other organism dies too due to lack of oxygen

Insecticides:
used to kill insects are usually non-biodegradable such as dichlorodiphenyltrichloroethane. They can remain in the soil or water for many years and may poison fish or animals when consumed in high concentrations. DDT is insoluble in water, and when accumulated in bodies of consumers will be passed to the top of the food chain. Top consumers of food chain will suffer from toxic effects due to bioaccumulation.

Impacts of biomagnification
The increase in concentration of a substance such as dichlorodiphenyltrichloroethane that occurs in food chains. Biomagnification occurs across all trophic levels.