How does nutrient spiraling describe nutrient movement in running water?

In the context of inland water ecosystems, nutrient spiraling is a concept used to describe the movement and cycling of essential elements within running water (lotic) systems.

Because running waters are characterized by unidirectional flow, nutrients do not simply cycle in a stationary loop as they might in a lake. Instead, as nutrients are transported downstream by the current, they are repeatedly taken up by organisms, utilized in biological processes, and eventually released back into the water or sediment through excretion or decomposition. This process of downstream transport coupled with biological uptake and release creates a spiral-shaped pathway rather than a closed circle.

This concept helps explain how biogeochemical processes function in streams and rivers, where the processing of elements is intrinsically linked to their continuous downstream movement.1