Interactions Between Macro- and Microorganisms and the Effects on Nitrogen Cycling in Marine Sediments

Book excerpt: In recent years there has been an effort to include the effects of biotic, as well as abiotic variables, in studies of ecosystem function. In marine benthic systems, numerous studies have identified a link between bioturbation and ecosystem function, the nature of which varies with invertebrate species identity, diversity, behaviour, environmental context and other traits. Despite clear links between invertebrate activity, ecosystem function and the biogeochemical properties of sediments that have been well documented over a number of years, relatively little is known about the mechanisms by which microbially mediated processes are affected by invertebrates. Without this knowledge, the variations in ecosystem function observed under different conditions cannot be explained and the relationship between biodiversity and ecosystem function cannot be fully understood. Nitrogen cycling is of particular interest since in marine systems primary productivity is often limited by N availability and nitrogen also interacts with other nutrient cycles.