Construction and Analysis of Static, Structured Models of Nitrogen Cycling in Coastal Ecosystems

Abstract

Microbial processes often dominate biogeochemical cycling within ecosystems. Therefore, microbial ecology interfaces with ecosystem ecology as appropriately as plant or animal ecology does. However, it is difficult for many microbiologists to interpret ecosystem-level phenomena. Often field measurements are made separately on individual components of an ecosystem. Thus one measures a single process, such as phytoplankton primary productivity, or a single assemblage of organisms, such as benthic (i.e., referring to sediments) microalgae. The interactions of components are inferred from observations of patterns of several variables over time or space. Or one conducts experiments using a limited number of variables where inferences involve only direct interactions of a few components. It is more difficult to examine indirect influences of one component on another or to simultaneously evaluate numerous interactions. We have found that constructing and analyzing simple mathematical models can be useful in greater synthesis of microbiological and ecological information (Christian et al. 1986; Christian and Wetzel 1991). Modeling provides a mechanism by which one can extend inferences to include numerous components and both direct and indirect interactions simultaneously.