Game of traits: diatom functionality in a changing landscape

Temporary ponds (TPs) are ephemeral freshwater habitats underlying seasonal drying creating highly dynamic environments. Here, for the first time, we focused on the trait analysis of benthic diatom communities along an elevational and seasonal gradient, aiming at: a) analysing taxonomic and functional α diversity indices variations; b) discerning whether or not seasonality and elevation affected taxonomic and functional β diversity; c) investigating the main physical and chemical factors influencing diatom communities. Among the seasonal changes, diatom guild-based communities exhibited significant variations only for high-profile guild. Seasonality appeared not influencing diatom taxonomic and functional α diversity, while the effect of elevation was statistically significant for taxonomic Shannon (TSha), Simpson (TSim) and Evenness (TEve). Furthermore, our results highlighted that neither seasonality nor elevation significantly influenced total taxonomic and functional β diversity, with the turnover component accounting for most of the observed variation. However, taxonomic β diversity showed substantial seasonal and elevational fluctuations, unlike functional β diversity, which was not driven by neither elevation nor seasonality. Physical parameters (Temperature, pH) exerted a significant influence on taxonomic α diversity, while Oxygen Reduction Potential and Total Dissolved Solids were identified as the main drivers of diatom functional α diversity. Differently, changes in Temperature, Resistivity and Dissolved oxygen emerged as important predictors for shaping elevational taxonomic β diversity. Our results emphasize the importance of considering multiple facets of biodiversity when investigating diatom communities in temporary ponds, as different aspects may exhibit distinct patterns and be shaped by different ecological drivers, particularly in high-elevation systems.