Impacts of deforestation
1)When the trees are removed,the topsoil is exposed to directly to the force of the rain. Without the roots to hold soil together,the topsoil which is the most fertile layer gets washed away or eroded during heavy rain, especilly when the rain falls on steep slopes.
2)Eroded soil may be deposited in rivers and streams, blocking the flow of water causing floods.
3)Sunlight now falls directly onto the soil.Water evaporate rapidly from the soil, which then hardens and barren.Plants can no longer grow and organisms that feed on these plants will go die off without food.This is called desertification
4)It also causes climate change.When the trees are cleared, the area becomes dry and warm and annual rainfall decreases
www.mcgarrigles.com Impacts of over-fishing
If fishing practices are not controlled, some species of fish will be caught faster than they can be replaced. Young fish that are caught will not have a chance to grow and reproduce. Hence, fish populations will decrease.
If fishing practices are not controlled, some species of fish will be caught faster than they can be replaced. Young fish that are caught will not have a chance to grow and reproduce. Hence, fish populations will decrease.
www.greenpeace.org Impacts of eutrophication
Chemical fertilisers containing nitrates and phosphates are used to increase the yield of crops. However, the overuse of these fertilisers may cause water pollution. Nitrates and phosphates in the fertilisers leads to the profuse growth and multiplication of algae and water plants in the river or lake. Submerged algae and plants die due to lack of sunlight. The dead bodies of the algae and water plants are decomposed by bacteria. Bacteria grow and multiply rapidly, using up the oxygen in the water. Other organisms such as fish die due to lack of oxygen.
Impacts of biomagnification/bioaccumulation
Insecticides are substances used to kill insects. However, insecticides may end up affecting other organisms as well. For example, insecticides such as DDT (dichlorodiphenyltrichloroethane) are non-biodegradable. This means that they cannot be broken down by microorganisms like bacteria. They can remain in the soil or water for many years. Insecticides may be carried by rainwater into streams, rivers and lakes. In high concentrations, they may poison fish or animals that take in the polluted water or feed on the contaminated fish.
Chemical fertilisers containing nitrates and phosphates are used to increase the yield of crops. However, the overuse of these fertilisers may cause water pollution. Nitrates and phosphates in the fertilisers leads to the profuse growth and multiplication of algae and water plants in the river or lake. Submerged algae and plants die due to lack of sunlight. The dead bodies of the algae and water plants are decomposed by bacteria. Bacteria grow and multiply rapidly, using up the oxygen in the water. Other organisms such as fish die due to lack of oxygen.
Impacts of biomagnification/bioaccumulation
Insecticides are substances used to kill insects. However, insecticides may end up affecting other organisms as well. For example, insecticides such as DDT (dichlorodiphenyltrichloroethane) are non-biodegradable. This means that they cannot be broken down by microorganisms like bacteria. They can remain in the soil or water for many years. Insecticides may be carried by rainwater into streams, rivers and lakes. In high concentrations, they may poison fish or animals that take in the polluted water or feed on the contaminated fish.
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