Biodiversity and aquatic ecosystem functioning: A mini-review

Ecosystem functioning depends on multiple interactions among physical, chemical and biological factors. Indeed, ecosystem processes (e.g., productivity and nutrient recycling) result directly from the diversity of functional traits in biotic communities, which in turn are determined by species composition and diversity. Species diversity results both from biotic introductions and from environmental pressures. As a result, changes in biodiversity in response to environmental selection pressures tend to have a direct impact on ecosystem processes. The relationships between biodiversity and ecosystem functioning have been the focus of numerous research studies for several years. Based on these studies, it appears that a low level of biodiversity allows an ecosystem to function effectively under constant conditions, but that greater biodiversity is called for in fluctuating environments. In this paper, we outline the concepts underlying the relationships between biodiversity and ecosystem functioning, and illustrate these concepts with examples from aquatic ecosystems. The importance of spatial scale will also be considered.