Newbold, J.D. 1987. Pages 303–327 in J.F. Craig and J.B. Kemper (editors). Regulated streams. Springer, Boston, Massachusetts.
The term spiralling refers to the coupled processes of cycling and downstream transport of nutrients. The intuitive notion of the spiral is, most simply, that of a nutrient cycle that fails to close in place in a stream, but rather is stretched by transport along the longitudinal axis of the stream (Elwood et al. 1983). At a somewhat more complex level, we may envision the ecosystem as a set of compartments representing various organic and inorganic forms of the nutrient, but instead of being boxes, these compartments are strips or tubes lying along the length of the stream. Each tube slides downstream at some characteristic rate, some at the velocity of water, others with geologic slowness. Our smooth spiral is now replaced by an erratic pathway, consisting of lateral exchanges among compartments and varying rates of longitudinal transport.