Freshwater Ecology Practice Test

Flowing-water systems are called lotic. The key feature of lotic ecosystems is the movement of water, as seen in streams and rivers, which creates currents, turbulence, and a gradient of habitats—from fast riffles to deeper pools. This flowing condition shapes which organisms can live there and influences oxygenation, nutrient transport, and sediment dynamics, all of which are defining aspects of these systems. In contrast, lentic ecosystems describe standing-water bodies like lakes and ponds where water movement is minimal. The riparian zone refers to the vegetated area along the watercourse that interacts with the stream but is not itself the water system. Ecosystem is a broad term for any living community and its physical environment, not specifically describing flowing water.