19 - Role in Nutrient Cycling in Streams

Abstract

This chapter explores the role of nutrient cycling in streams. Nutrient cycling in ecosystems includes a sequence of processes, uptake of inorganic (and in some cases organic) forms of elements by biota, transfer of these elements from one organism to another (through food chains), release back to the environment in available forms (release in soluble forms, remineralization), and element reassimilation by organisms. The rate of nutrient cycling is often quantified as the turnover rate of nutrients within an ecosystem compartment (e.g., water, algae, detritus) per unit time (expressed as time-l). Nutrient cycling is also sometimes presented as the flux of organic nutrients remineralized per unit time. However, the latter expression does not provide information on the contribution of remineralization to assimilation, and thus, can be misleading as an index of the importance of nutrient cycling in meeting nutrient demands within ecosystems. This chapter considers the direct effects of benthic algae on nutrient cycling, including processes such as nutrient uptake and remineralization, as well as indirect effects of benthic algae on nutrient cycling via their modification of streambed hydraulic properties and algal/herbivore interactions.