Elemental Dynamics in Streams

Abstract

We discuss elemental dynamics in streams and seek to identify areas where there are critical gaps in our understanding. Both landscape-level processes (e.g., geology, land-use practices, vegetation) and heterogeneous in-stream processes influence the supply and availability of elements to the stream biota. Stream ecologists need to consider the relative availability of different compounds or groups of compounds to the biota rather than lumping all forms of an element into operationally-defined units such as dissolved organic nitrogen or carbon. The impact of short-term events like storms on the elemental dynamics in streams needs to be assessed and compared with other controls. The relative importance of longitudinal (upstream), lateral (riparian zone, flood-plains), and in-stream controls of supply and availability of elements needs to be compared in a variety of streams. Availability of essential elements is a key factor controlling rates of primary productivity and decomposition in streams. Whole system manipulations offer a valuable tool for understanding the interactions between elements and all components of the stream food web. We include an action plan of developments that would assist researchers in addressing some of the critical gaps we have identified in our understanding of elemental dynamics in streams.