Example of Lotic ecosystem is -

Aquatic ecosystems are broadly classified into two categories based on the movement of water: Lotic and Lentic.

• Lotic ecosystems (from Latin lotus, meaning washed/running) consist of moving or flowing water. Examples include rivers, streams, brooks, and springs. These systems are characterized by unidirectional flow and high oxygen levels.
• Lentic ecosystems (from Latin lentus, meaning sluggish/still) consist of standing or still water. Examples include ponds, lakes, marshy areas, and swamps.

Therefore, among the given options, Rivers is the correct example of a lotic ecosystem, while ponds, marshes, and swamps are examples of lentic or wetland ecosystems.