Macroinvertebrate assemblages of natural springs along an altitudinal gradient in the Bernese Alps, Switzerland

Abstract

-Alpine springs are sensitive ecotones which are inhabited by highly adapted organisms. Studies on how the species assemblages change vertically have not been conducted previously. We investigated 35 natural springs along an altitudinal gradient of about 2000 m in a valley in the Bernese Alps over 2 years. The aim of this study was to investigate the changes of the macroinvertebrate assemblages of natural springs along this gradient and to find out which environmental factors determine the distribution of the species along the altitudinal gradient. The spring fauna was quantitatively sampled three times and a wide range of environmental parameters were measured. The species richness significantly decreased with increasing altitude and the composition of the species assemblages changed distinctively along the altitudinal gradient. The low-elevation springs were dominated by crenobiont species, whereas high-altitude springs were mostly inhabited by taxa typical for Alpine headwaters in general. The mid-altitudinal range was a transition zone where crenobiont and alpine species co-existed. The water temperature was an important factor determining the species richness and the composition of macroinvertebrate assemblages of the springs at different altitudes. Moss, stones and the degree of forestation also had a significant influence on the composition of the macroinvertebrate assemblages. This study helps to understand the distribution of the spring fauna along altitudinal gradients. Knowing the current distribution ranges is an important prerequisite to predict potential changes of the species distribution, caused by global change, in the future.

Limno-ecological characteristics and distribution patterns of spring habitats and invertebrates from the Lowlands to the Alps

“…The investigation of natural springs in the Bernese Alps has just commenced (Wigger and von Fumetti 2013;Wigger et al 2015). First results of the research, focused on possible consequences of ongoing climatic and land-use changes, suggest that invertebrate assemblages will react differently at different altitudes (Wigger et al 2015).…”

“…First results of the research, focused on possible consequences of ongoing climatic and land-use changes, suggest that invertebrate assemblages will react differently at different altitudes (Wigger et al 2015). It became evident that springs at higher altitudes are characterized not only by a lower annual mean temperature, but also by a lower thermal amplitude and a lower percentage of crenobionts (Wigger et al 2015). Since wide parts of the medium-altitude range are used as Alpine meadows, most springs below 1500 m.a.s.l.…”

Temperature variability and its influence on macroinvertebrate assemblages of alpine springs

“…The mean and median water temperatures of the investigated springs decreased significantly with altitude, as has been found for other alpine springs (Cantonati, 1998;Küry et al, 2017;Wigger et al, 2015). Spring water temperature is meant to reflect the mean annual air temperature of the region, no matter if at low or high altitude (Ward, 1994).…”

“…The influence of substrate composition on the macroinvertebrate assemblages was thoroughly investigated by Wigger et al (2015) and…”

“…This sampling time frame is in concordance with recommendations of Lubini-Ferlin, Stucki, Vicentini, and Küry (2014). At each sampling time, four samples were taken in each spring in the first 5 m after the outflow (Von Fumetti et al, 2007;Wigger et al, 2015). Samples were taken proportionally to the main substrate types mapped with the evaluation sheet of Hotzy and Römheld (2008).…”