Effect of glyphosate on the sporulation of aquatic fungi: an in-vitro experience

Glyphosate, a herbicide widely used in agriculture, has adverse effects on aquatic ecosystems. This study aimed to assess the repercussions of in-vitro exposure to varying concentrations of glyphosate (1500, 3000, and 6000 μg l⁻¹) on  sporulation of fungi that colonize Typha latifolia (L.) leaves. Although the results were not significant, our bioassay revealed a trend of a 50% increase in fungal sporulation at lower glyphosate concentrations compared to the control, with an effect size of approximately 100%. Thirteen aquatic fungi taxa were identified, belonging to the phylum Ascomycota. Amniculicola longissima (Anguillospora longissima) was dominant among fungi associated with decaying leaves, exhibiting a tendency of decreased sporulation rate at higher glyphosate concentrations. Conversely, Brachysporium sp. demonstrated significantly higher spore abundance at the lowest herbicide level. Some fungal taxa, such as Cordana sp., exhibited an inhibition of sporulation rates in the presence of glyphosate. On the other hand, Curvularia sp. and Sporidesmium sp. were only found in treatments with glyphosate concentrations > 3000 ppm. These findings underscore the potential adverse effects of glyphosate on sporulation of some aquatic fungi, pivotal microorganisms that are considered key in the decomposition of organic matter in aquatic ecosystems and consequently in water self-purification processes. Hence, it is plausible that this herbicide alters the dynamics of decomposition, modifying the recycling of organic matter and thereby influencing the trophic networks of aquatic ecosystems. These results represent a preliminary investigation that establishes a baseline to understand the effect of glyphosate on aquatic fungi, a topic that has been poorly studied.