Ecology of the cold-adapted species Nebria germari (Coleoptera: Carabidae): the role of supraglacial stony debris as refugium during the current interglacial period

TL;DR

This study investigates how supraglacial stony debris serves as a refugium for the cold-adapted beetle Nebria germari in the Alps, highlighting its ecology, phenology, and habitat stability amid climate change.

Contribution

It provides new insights into the ecology and phenology of Nebria germari on supraglacial debris, emphasizing its role as a refugium during current interglacial conditions.

Findings

Supraglacial debris offers stable, colder, and wetter microhabitats.

Nebria germari populations are spring breeders on debris, unlike historical autumn breeding.

Debris habitats support suitable life-cycle conditions with reduced competition.

Abstract

In the current scenario of climate change, cold-adapted insects are among the most threatened organisms in high-altitude habitats of the Alps. Upslope shifts and changes in phenology are two of the most investigated responses to climate change, but there is an increasing interest in evaluating the presence of high-altitude landforms acting as refugia. Nebria germari Heer, 1837 (Coleoptera: Carabidae) is a hygrophilic and cold-adapted species that still exhibits large populations on supraglacial debris of the Eastern Alps. This work aims at describing the ecology and phenology of the populations living on supraglacial debris. To this end, we analysed the populations from three Dolomitic glaciers whose surfaces are partially covered by stony debris. We found that supraglacial debris is characterised by more stable colder and wetter conditions than the surrounding debris slopes and by a shorter snow-free period. The populations found on supraglacial debris were spring breeders, differently from those documented in the 1980s on Dolomitic high alpine grasslands, which were reported as autumn breeders. Currently Nebria germari seems therefore to find a suitable habitat on supraglacial debris, where micrometeorological conditions are appropriate for its life-cycle and competition and predation are reduced.