Influence of biodiversity on the functionality of activated sludge communities

We are addressing a critical and unresolved ecological question: When are community composition and biodiversity important for the provision of a particular ecosystem function and when are they not? We hypothesize that community composition and biodiversity are more important for rare ecosystem functions than for common ecosystem functions. If an ecosystem function is rare, then differences or changes in community composition could have profound effects on the biotransformation rate of that function. In contrast, if an ecosystem function is common, then differences or changes in community composition are unlikely to have an effect on that function.