After the aswan high dam was built on the nile river, the rate of parasitic worm infection doubled in the human population near the dam. as a result of building the dam, the flow of the nile changed. this changed the habitat, which resulted in an increase in its population of a certain aquatic snail. the snails, which were infected, released larvae of the worm. these larvae then infected humans. this situation best illustrates that:
A. the influence of humans on a natural system is always negative in the long term
B. the influence of humans on a natural system can have unpredictable negative impacts
C. human alteration of an ecosystem does not need to be studied to avoid ecological disaster
D. human alteration of an ecosystem will cause pollution and loss of finite resources.
The correct answer is option (B) the influence of humans on a natural system can have unpredictable negative impacts.
The biosphere refers to the biologically inhabited part of the earth in association with the atmosphere, hydrosphere and the lithosphere. Human beings have been influenciung this natural system of biosphere causing numerous negative impacts. This finally affects all the living organisms of the biosphere.
Human activities like industrialization, construction of dams, chemicals based agriculture and others have been affecting the habitats. Construction of the dams changes the habitat. This change in the habitat can endanger or increase certain species. The change in the habitat can affect the abiotic factors as well as the biotic factors. In case of the river Nile, it increased the snails which were infected by the larvae of parasitic worms. Thus, doubling the infection of parasitic worms in the humans.
When the natural system of rivers have been influenced by the humans, it always has the negative effects on the life.
