Discuss the impact of human activities on our ecosystem, highlighting issues on deforestation, over-fishing, eutrophication(increase in chemical nutrients) and biomagnifications(increase in concentration of a substance, such as pesticides).

Humans beings are continually using and depleting the world’s natural resources, upsetting the balance of nature in many places. Some of the ways humans destroy the environment is:

Deforestation. It is the clearing of forest, to increase the amount of land for agriculture, industries or settlement. However, deforestation may lead to soil erosion, flooding, desertification(desert-like conditions) and climate change.
Uncontrolled fishing practice. As the population of humans increases, so does the demand of fishes. Some fishes are over-fished due to the demand of large quantity. Also, most of the modern fishing gear lead to the destruction of marine life, such as turtles and corals. Some use Trawling, where they trap many unwanted species in the process and Dredging, scraping the seabed, destroying corals, in search for scallops. If fishing practices are not controlled, the number of fishes will decline and the number of fishes lost will not be replaced as quickly. Also, other marine organisms that are unintentionally caught often dies, causing the some species to be endangered or extinct.
Pollution. It is a process where harmful substances are released to the environment, damaging it. Sewage is waste matter from home or industries. Untreated sewage may contain disease-causing bacteria that may cause diseases if they are released to rivers or lakes for human consumption. It may cause an outbreak of diseases(epidemic). Eutrophication is caused when fertilizers(contain nitrates and phosphates) are washed away into the rivers, causing a profuse growth and multiplication of algae and water plants in the river or lakes. Its effects are lack of oxygen, severe reductions in water quality, fish and other animal population. Inorganic waste are thrown dump in large amount in rivers and lakes. They may include poisonous metals such as mercury, lead, zinc, arsenic, cadmium. Insecticides are used to kill insects, however, it may be washed out to a river or lake and in high concentration may poison fish or animals that take in the polluted water or contaminated fish. Insecticides like DDT(dichlorodiphenyltrichloroethane) is insoluble in water. Organisms cannot break down DDT. Hence, DDT accululate in the bodies of consumers. This results in the insecticide being passed along food chains, increasing in concentration in the bodies of organisms along the trophic levels. This process is called bioamplification.