Do Isopropylammonium Glyphosate and LiCl Impact the Spore Diversity and Functions of Aquatic Fungi Involved in Plant Litter Decomposition in Streams?

Abstract

Glyphosate based-herbicides are stressors of great concern because they can impact aquatic ecosystems. Similarly, lithium, a metal, is currently of concern because of its increasing use worldwide. Because glyphosate-based herbicides and lithium might co-occur in aquatic environments, there is a need to assess their impacts on aquatic organisms, such as aquatic fungi, as they play a key role in plant litter decomposition in streams. Microcosm assays were used to examine the effects of lithium and the herbicide isopropylammonium glyphosate (IPAG), alone or in mixtures, on microbial leaf mass loss, total fungal sporulation and biomass production. IPAG (alone and combined with LiCl) neither affected plant litter decomposition nor fungal biomass production, but boosted total fungal sporulation. Dimorphospora foliicola, the most tolerant species among the twelfth leaf inhabitant fungal species, is the major contributor to total fungal sporulation. IPAG interacts with LiCl in the total fungal sporulation and sporulation of D. foliicola, A. tetracladia, and F. curvula, indicating a species dependent-effect. IPAG alone or combined with LiCl greatly decreased the diversity of spores, as did as LiCl alone, but to a lesser extent. Finally, aquatic fungal communities reveal redundancy and resiliency to IPAG and LiCL, maintaining the health of aquatic ecosystems.