Which statement illustrates how human activities can most directly change the dynamic equilibrium of an ecosystem?
water pollution causes a decrease in fish populations in a river.
a hurricane causes a stream to overflow its banks.
increased wind increases water evaporation from a plant.

Water pollution causes a decrease in fish populations in a river.

Explanation:

An ecosystem is a biotic community which includes abiotic (non-living) and biotic (living) components. The abiotic components includes water, sunlight, wind, soil and temperature whereas the biotic components includes the living beings such as plants, animals, microbes and other. The dynamic equilibrium of the ecosystem can be defined as the condition in which the abiotic factors of the ecosystem supports the life of the biotic factors without undergoing any drastic change which could negatively affect the population of living beings.

The river water is an abiotic factor which can be a habitat of large diversity of marine flora and fauna. The pollution of water could negative affect the population of the fish residing in the river. This will disturb the balance of ecosystem. As, in the ecosystem various species interact with one another to survive. Hence, the dynamic equilibrium will be changed.