Which of the following is an example of a lotic ecosystem?

A lotic ecosystem is characterized by flowing water, which is a key aspect that distinguishes it from lentic ecosystems, where water is standing or still. Streams are classic examples of lotic ecosystems because they consist of water that moves in a continuous flow, typically as part of a river system, and can include various features such as riparian zones, waterfalls, and riffles.

Streams provide unique habitats for a diverse range of aquatic organisms adapted to life in flowing water, such as certain species of fish, insects, and plants. The flow of water in these ecosystems affects sediment transport, nutrient cycling, and oxygen levels, all of which play crucial roles in defining the ecological characteristics and health of a stream.

In contrast, ponds, lakes, and wetlands represent lentic ecosystems where water is generally stationary. These systems may have different ecological dynamics, including stratification and varied nutrient cycling processes due to the lack of significant water movement. Hence, the defining feature of a lotic ecosystem is its flowing water, which is aptly represented by streams.