Flow intermittency negatively affects three phylogenetically related shredder stoneflies by reducing CPOM availability in recently intermittent Alpine streams in SW-Italian Alps

Elena Piano,Alberto Doretto,Stefano Fenoglio,Francesca Bona,Elisa Falasco,Laura Gruppuso

doi:10.1007/s10750-020-04399-4

Elena Piano, Alberto Doretto + Show 4 more

Open Access

https://doi.org/10.1007/s10750-020-04399-4

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Abstract

Several Alpine streams are currently facing recurrent summer drying events with detrimental consequences on stream detritivores, i.e., shredders, due to negative effects via changes the organic matter (CPOM) availability. We examined the ecological requirements of three phylogenetically related shredder genera belonging to the family of Nemouridae (Plecoptera), namely Nemoura, Protonemura and Amphinemura, in 14 Alpine streams recently facing recurrent summer flow intermittency events. We evaluated the overlap among their ecological niches measured in terms of hydraulic stress, substrate composition, changes in CPOM availability and competition with other shredder taxa (i.e., presence of individuals of other shredders) and we examined potential changes in their ecological niches between permanent and intermittent sites. The ecological niches of Protonemura and Amphinemura overlap broadly, but not with Nemoura, suggesting only partial potential competition. The reduced CPOM availability decreased the individual abundance of the three genera in intermittent sites, where they consistently preferred microhabitats with high CPOM availability and low competition with other shredder taxa, possibly due to food limitation. Overall, our results emphasize how the negative effect of flow intermittency on shredders in Alpine streams is mainly due to the decrease in CPOM availability, with consequent potential bottom up effects on stream ecosystem functionality.

Highlights

IntroductionThese newly temporary streams are characterized with recurrent non-flow events, occurring in summer, followed by rewetting phases in late autumn (Fenoglio et al, 2010) due to the interactive effects of both climate change and anthropogenic disturbance (Belmar et al, 2019; Bruno et al, 2019)
Some studies investigated the effect of flow intermittency on the diversity of this trophic group in Alpine streams (e.g., Fenoglio et al, 2007; Doretto et al, 2018; Piano et al, 2019a), little is known about how these events may alter the ecological parameters that determine the niches of shredder taxa
As we expected differences in the ecological requirements of Nemouridae, we first examined whether the examined genera differed in the dimension of their realized ecological niches and whether they overlap in their ecological requirements

Summary

Introduction

These newly temporary streams are characterized with recurrent non-flow events, occurring in summer, followed by rewetting phases in late autumn (Fenoglio et al, 2010) due to the interactive effects of both climate change and anthropogenic disturbance (Belmar et al, 2019; Bruno et al, 2019) These recurrent drying events are expected to alter the distribution of lotic biota by influencing physical conditions and distribution of trophic resources (e.g., Calapez et al, 2014; Elias et al, 2015; Milner et al, 2017; Doretto et al, 2018; Falasco et al, 2018; Piano et al, 2019a; Doretto et al, 2020a). Some studies investigated the effect of flow intermittency on the diversity of this trophic group in Alpine streams (e.g., Fenoglio et al, 2007; Doretto et al, 2018; Piano et al, 2019a), little is known about how these events may alter the ecological parameters that determine the niches of shredder taxa

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