Effects of aquatic hyphomycete species richness and identity on leaf mass loss, fungal biomass and conidium production

Abstract

Biodiversity is rapidly declining as a consequence of several human activities, leading to an increased interest in determining how species loss affects ecosystem functioning. The relationship between biodiversity and ecosystem processes has been widely documented in terrestrial systems. Comparatively few studies have been conducted in aquatic systems. Aquatic hyphomycetes, an ecological group of fungi that play a key role in leaf litter decomposition in streams, were used to investigate how species loss might affect decomposition processes. The effects of species richness and species identity on leaf mass loss, fungal biomass and conidium production were tested in microcosms. Alder leaf disks were inoculated with combinations of one to four aquatic hyphomycete species (Articulospora tetracladia, Flagellospora curta, Geniculospora grandis and Heliscus submersus) and continuously aerated under artificial light for 27 days. Both species richness and identity significantly affected fungal biomass and total conidium production (as numbers or biomass of conidia), whereas only species identity had a significant effect on leaf mass losses. In mixed cultures, leaf mass losses, fungal biomass and conidium production were greater than expected from the sum of the contribution of each species in monocultures.