Response of stream fungi on decomposing leaves to experimental drying

Abstract

Climate change may lead to increased droughts in the future, which in turn may lead to increased periods of stream drying. We conducted an experiment to test the effects of drying on fungal communities and microbial activity on decaying leaves from a stream. Our experimental setup included immersion of maple leaf cores for 2 weeks in a small stream to allow for the colonization of microbes. Leaves were then subjected for 2 weeks to four treatments: one control, where leaves stayed immersed in the stream, and three drying treatments in different settings (field, lab, and oven). Leaves were then returned to sterile water for 2 weeks of recovery. Microbial respiration declined after all drying treatments compared to the control, with the oven‐dried leaves taking the longest time to recover. All drying treatments had similar respiration to each other and the control after 2 weeks of immersion recovery. Fungal communities on the leaves were assessed by polymerase chain reaction amplification of fungal DNA from leaves followed by denaturing gradient gel electrophoresis (DGGE). Most treatments had very similar communities based on phylotypes from DGGE, with little change during drying and recovery compared to immersion controls. However, the oven‐dried leaves had a very different community developing during recovery. There were no differences in diversity or richness of DGGE phylotypes among treatments after recovery. Overall, the fungal communities, in our experiment, appeared resilient to the effects of short‐term drying, with little change to community structure and relatively fast recovery in activity after rewetting.

Annual patterns of litter decomposition in the channel and riparian areas of an intermittent stream

“…In forested streams, where the food web is mainly based on the leaf litter inputs from surrounding ecosystems (Wallace et al 1997), the water stimulates leaching of leaf soluble compounds (Gessner et al 1999) and enhances the mechanical fragmentation of detrital material due to physical abrasion (Ferreira et al 2006). This boosts the decomposer activity of microbial assemblages (Mora-Gómez et al 2018;Niyogi et al 2020) and invertebrate detritivores (Martínez et al 2015;Abril et al 2016). Therefore, ecosystems such as perennial streams, are more efficient in catabolizing detrital material than surrounding terrestrial ecosystems (Hutchens and Wallace 2002) or than intermittent streams due to the more or less elongated presence of the dry periods that characterize these systems (Pinna and Basset 2004;Datry et al 2011;Martínez et al 2015).…”

Changes in Fungal Community Structure in Freshwater Canals across a Gradient of Urbanization

“…Aquatic fungi convert refractory leaf litter to more bioavailable nutrients and energy in aquatic food webs [26]. Stream fungi, mainly aquatic hyphomycetes, are impacted by multiple stressors, including temperature, pH, nutrients and toxic chemicals [27]. As fungi degrading leaf litter are more sensitive to disruption than their bacterial counterparts, fungal community analysis provides a good model to evaluate the effects of contaminants on complex ecological systems [28].…”