title: Biodiversity increases functional and compositional resistance, but decreases resilience in phytoplankton communities.
abstract: There is now ample evidence that biodiversity stabilizes aggregated ecosystem functions, such as primary production, in changing environments. In primary producer systems, this stabilizing effect is found to be driven by higher functional resistance (i.e., reduced changes in functions by environmental changes) rather than through higher functional resilience (i.e., rapid recovery following environmental changes) in more diverse systems. The stability of aggregated ecosystem functions directly depends on changes in species composition and by consequence their functional contributions to ecosystem functions. Still, it remains only theoretically explored how biodiversity can stabilize ecosystem functions by affecting compositional stability. Here, we demonstrate how biodiversity effects on compositional stability drive biodiversity effects on functional stability in diatom communities. In a microcosm experiment, we exposed 39 communities of five different levels of species richness (1, 2, 4, 6, and 8 species) to three concentrations of a chemical stressor (0, 25, and 250 μg/L atrazine) for four weeks, after which all communities were transferred to atrazine-free medium for three more weeks. Biodiversity simultaneously increased, increasing functional and compositional resistance, but decreased functional and compositional resilience. These results confirm the theoretically proposed link between biodiversity effects on functional and compositional stability in primary producer systems, and provide a mechanistic underpinning for observed biodiversity-stability relationships. Finally, we discuss how higher compositional stability can be expected to become increasingly important in stabilizing ecosystem functions under field conditions when multiple environmental stressors fluctuate simultaneously.
authors.affiliation: Laboratory of Environmental Toxicology and Applied Ecology, Ghent University, Coupure Links 653, Ghent, 9000, Belgium.
authors.forename: Jan M
authors.initials: JM
authors.lastname: Baert
authors.affiliation: Research Unit of Environmental and Evolutionary Biology, University of Namur, Rue de Bruxelles 61, Namur, 5000, Belgium.
authors.forename: Frederik
authors.initials: F
authors.lastname: De Laender
authors.affiliation: Laboratory of Protistology & Aquatic Ecology, Ghent University, Krijgslaan 281-S8, Ghent, 9000, Belgium.
authors.forename: Koen
authors.initials: K
authors.lastname: Sabbe
authors.affiliation: Laboratory of Environmental Toxicology and Applied Ecology, Ghent University, Coupure Links 653, Ghent, 9000, Belgium.
authors.forename: Colin R
authors.initials: CR
authors.lastname: Janssen
mesh_terms: D001280:Atrazine / Q000494:pharmacology; D044822:Biodiversity; D018533:Biomass; D017377:Diatoms / Q000187:drug effects / Q000502:physiology*; D006540:Herbicides / Q000494:pharmacology; D010839:Phytoplankton / Q000145:classification* / Q000187:drug effects / Q000502:physiology*; D011157:Population Dynamics
chemical_list: D006540:Herbicides; D001280:Atrazine
keywords: diatoms; ecosystem functions; evenness; herbicide; primary production; stability