Initial Colonization of New Terrain in an Alpine Glacier Foreland by Carabid Beetles (Carabidae, Coleoptera)

Abstract

The melting of glaciers in the European Alps has exposed new terrain in the last decades. Ground beetles (Carabidae, Coleoptera) are among the first colonizers of this new alpine land. Since 1999, we have studied the ground beetle assemblages of the recently deglaciated areas in the Hornkees glacier foreland (Zillertal Alps, Austria). Data were collected in July 1999, 2001, 2007, and 2009. Two species of Carabidae, Nebria jockischii and Nebria germari, were dominant in the areas immediately below the glacier in all sampling periods. The occurrence of Nebria jockischii larvae very close to the edge of the glacier strongly suggests that reproduction occurred in the area which had been ice-free for only one year. Comparison of the carabid beetle assemblages from the recently deglaciated areas with those from neighboring and longer exposed areas indicates that the first colonizers continuously expanded their range following the path of the glacial retreat. We hypothesize that Nebria jockischii populated the new alpine terrain by initial migration from the banks of the glacial stream, whereas Nebria germari probably colonized the recently deglaciated area by migration from the lateral moraines. These carabid beetles represent the first predatory insects in the initial phase of colonization of the Hornkees foreland.