Realized Fungal Diversity Increases Functional Stability of Leaf Litter Decomposition Under Zinc Stress

Abstract

Freshwaters include some of the most impaired systems on Earth with high rates of species loss, underscoring the significance of investigating whether ecosystems with fewer species will be able to maintain ecological processes. The environmental context is expected to modulate the effects of declining diversity. We conducted microcosm experiments manipulating fungal inoculum diversity and zinc concentration to test the hypothesis that fungal diversity determines the susceptibility of leaf litter decomposition to Zn stress. Realized fungal diversity was estimated by counting released spores and by measuring species-specific biomasses via denaturing gradient gel electrophoresis. In the absence of Zn, positive diversity effects were found for leaf mass loss and fungal biomass through complementary interactions and due to the presence of key species. The variability of leaf decomposition decreased with increasing species number (portfolio effect), particularly under Zn stress. Results suggest that the effect of species loss on ecosystem stability may be exacerbated at higher stress levels.

Aquatic Hyphomycete Communities Associated with Decomposing Alder Leaf Litter in Reference Headwater Streams of the Basque Country (northern Spain)

“…The absence of this relationship is often explained by the high ecological redundancy of this group [14,43]. On the other hand, positive relationships have already been observed under laboratory controlled conditions [20,24,44] and in some studies carried out in natural systems [35], usually when comparing reference streams with highly impaired systems [7,21,41], where both taxa richness and ecosystem functioning are dramatically reduced. Our results indicate that, even under reference oligotrophic conditions, aquatic hyphomycete richness enhances leaf processing.…”

“…A possible explanation could be the ecological trophic redundancy of these fungi [43]. Additionally, this linkage seems to be variable when different impacts interact [34], masking the effects of these organisms on ecosystem functioning [24], especially when the community is exposed to several stresses [21,44].…”

Intraspecific traits change biodiversity effects on ecosystem functioning under metal stress

“…Three-way nested ANOVAs were used to test the effects of Cd, species number and species identity (nested in species number) as fixed factors on leaf mass loss and fungal biomass (Duarte et al 2006;Pascoal et al 2010). Differences between treatments were analysed by a Tukey's posttest (Zar 1996).…”

Denaturing Gradient Gel Electrophoresis (DGGE) in Microbial Ecology - Insights from Freshwaters

“…Das et al 2007;Duarte et al 2010;Mille-Lindblom et al, 2006;Nikolcheva et al, 2003) and in very early stages of the process ; 2) discriminate members of different fungal groups on decomposing plant-litter by using taxon specific primers (Nikolcheva & Bärlocher, 2004); 3) assess the diversity of conidia of aquatic fungi in the stream water (Raviraja et al, 2005); 4) analyse the effects of environmental factors and stressors on diversity and species composition (e.g. Duarte et al, 2008bDuarte et al, , 2009aSridhar et al, 2009); 5) assess individual contributions of fungal species or groups to total fungal biomass, using band intensities (Nikolcheva & Bärlocher, 2004;Pascoal et al, 2010); 6) test the efficiency of different primers to assess fungal and bacterial diversity ; 7) assess intraspecific diversity of aquatic fungal species (Seena et al, 2010a) and 8) detect shifts in aquatic microbial communities on fecal pellets of invertebrate detritivores feeding on different litter types .…”

“…18S rDNA (5' portion) Das et al, 2007;Duarte et al, 2010;MilleLindblom et al, 2006;Nikolcheva et al, 2003 ITS3GC(F)/ITS4(R) ITS Duarte et al, 2008bDuarte et al, , 2009aDuarte et al, ,b, 2010Duarte et al, , 2011Fernandes et al, 2009;Medeiros et al, 2010;Moreirinha et al, 2011;Nikolcheva & Bärlocher, 2004, 2005Pascoal et al, 2010;Pradhan et al, 2011;Raviraja et al, 2005; 2009 Bacteria…”