Towards a definition of environmental niches in alpine streams by employing chironomid species preferences

Georg H Niedrist,Leopold Füreder

doi:10.1007/s10750-016-2836-1

Georg H Niedrist, Leopold Füreder

Open Access

https://doi.org/10.1007/s10750-016-2836-1

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Abstract

Macroinvertebrates are widely used as indicators to detect and assess anthropogenic impacts on freshwater ecosystems. However, despite being considered useful in indicating effects of environmental change in alpine catchments, little is known about species preferences for local conditions in such environments. In exploring the occurrence of 59 taxa within the dipteran family Chironomidae in relation to key-environmental variables in alpine and sub-alpine streams, we showed that sediment load, water temperature, periphyton density, and fine particulate organic matter mostly explain assemblage structures. Two-way-cluster analyses identified stream-type specific assemblages, indicator value analysis defined indicator species for glacial and non-glacial streams, and weighted averaging regression models confined preferences for local environmental conditions by summing their optima and tolerance widths regarding environmental key factors. The definition of habitat requirements identified stenoecious taxa with preferences for high and low values of respective variables thus identified most suitable indicators for future studies. Our work reveals manifold preferences within the dominant benthic invertebrate family, underlines their enormous potential for monitoring purposes, and is a step forward in better understanding ecosystem properties and biodiversity. Fundamental requirements for these kinds of indicative traits, essential to understand cause–effect relationships in environmental change issues, are a robust taxonomy and a comprehensive set of physical and chemical data.

Highlights

Organisms, which successfully inhabit extreme environments, are living in the ecological optimum for existence and reproduction (Begon et al, 1996)
Even in relatively remote regions, e.g., high mountain protected areas, alpine stream ecosystems experience the consequences of climatic change including glacier retreat, altered water temperature, discharge dynamics as well as the availability of allochthonous and autochthonous organic matter (Braun et al, 2000; Zah & Uehlinger, 2001; Jansson et al, 2003; Knowles et al, 2006; Zemp et al, 2006)
In this respect, understanding the spatial and temporal patterns, as well as the determinants of the structure of chironomid assemblages, which form the main components of the benthic invertebrate fauna (Fureder et al, 2001; Lods-Crozet et al, 2001a), are fundamental for the application of this ubiquitous dipteran family as indicators (Butler et al, 2012)

Summary

Introduction

Organisms, which successfully inhabit extreme environments, are living in the ecological optimum for existence and reproduction (Begon et al, 1996). They tolerate harsh physical environmental conditions, grow at low temperatures, use limited food resources, and cope with predators and competing species (Wharton, 2002). One species’ ecological niche is quantified as a multidimensional hypervolume (Blonder et al, 2014), where the individual dimensions are specific environmental conditions and resources that define the requirements of the present species to persist. The characterisation of such niches in natural multi-species ecosystems is still debated (Soberon, 2007), independent methods have been developed for different uses (Blonder et al, 2014)

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