Intraguild predation in pioneer predator communities of alpine glacier forelands

Lorna Raso,Simon Plangg,Thomas Recheis,Daniela Sint,Michael Traugott,Silvia Brunner,Rüdiger Kaufmann,Rebecca Mayer

doi:10.1111/mec.12649

Abstract

Pioneer communities establishing themselves in the barren terrain in front of glacier forelands consist principally of predator species such as carabid beetles and lycosid spiders. The fact that so many different predators can co-inhabit an area with no apparent primary production was initially explained by allochthonous material deposited in these forelands. However, whether these populations can be sustained on allochthonous material alone is questionable and recent studies point towards this assumption to be flawed. Intraguild predation (IGP) might play an important role in these pioneer predator assemblages, especially in the very early successional stages where other prey is scarce. Here, we investigated IGP between the main predator species and their consumption of Collembola, an important autochthonous alternative prey, within a glacier foreland in the Ötztal (Austrian Alps). Multiplex PCR and stable isotope analysis were used to characterize the trophic niches in an early and late pioneer stage over 2 years. Results showed that intraguild prey was consumed by all invertebrate predators, particularly the larger carabid species. Contrary to our initial hypothesis, the DNA detection frequency of IGP prey was not significantly higher in early than in late pioneer stage, which was corroborated by the stable isotope analysis. Collembola were the most frequently detected prey in all of the predators, and the overall prey DNA detection patterns were consistent between years. Our findings show that IGP appears as a constant in these pioneer predator communities and that it remains unaffected by successional changes.

Highlights

Glacier forelands are the areas exposed as glaciers retreat
Our findings show that Intraguild predation (IGP) appears as a constant in these pioneer predator communities and that it remains unaffected by successional changes
Ko€nig et al (2011) studied the food web of the glacier foreland arthropod community in the Rotmoos valley in the Austrian Alps using stable isotope analysis. They concluded that 2–34 years after deglaciation, predator diet was composed principally of decomposers whereas an increase in cannibalism or intraguild predation was suggested by their data for later stages

Summary

Introduction

Glacier forelands are the areas exposed as glaciers retreat. Most of the world glaciers have been steadily retreating for the past 150–200 years (Zemp et al 2011), exposing more and more areas in front of them. Ko€nig et al (2011) studied the food web of the glacier foreland arthropod community in the Rotmoos valley in the Austrian Alps using stable isotope analysis. They concluded that 2–34 years after deglaciation, predator diet was composed principally of decomposers (collembolans) whereas an increase in cannibalism or intraguild predation was suggested by their data for later stages. In the late pioneer stage, a higher abundance and higher diversity of alternative prey are expected due to an increased plant cover and increased availability of detritus, thereby reducing IGP between predators. We look at this aspect by comparing niche overlap in IGP and collembolan prey among carabid beetles and arachnids in both early and late pioneer stages

Materials and methods

Results

Discussion