Characterization of the habitats colonized by the alien ground beetle Merizodus soledadinus at the Kerguelen Islands

Abstract

In the present work, we conducted a field-based study to identify the type of habitats colonized by the alien ground beetle Merizodus soledadinus at the Kerguelen Islands, southern Indian Ocean, and to delineate the spatial dynamics of this species. We used periodic trapping at several coastal habitats on Ile Haute (one of the islands from the Kerguelen archipelago), together with opportunistic active searches at other locations on this subantarctic archipelago. A total of 1081 sites were visited. Our data showed that adult M. soledadinus were mostly found near the tide drift line (372/ 540 obs., i. e., 69 %) in various habitats, including (1) in the foreshore under timber, (2) beneath stones in coastal areas near penguin colonies, and (3) in herbfields and meadows. It was previously assumed that the habitat distribution of this species was restricted to the herbfields of coastal areas, with our inland observations showing that M. soledadinus (265/ 541 obs., i. e. 49 %) occupied areas (1) in the vicinity of cushion-carpets, (2) along rivers and ponds beneath stones or mammal carrion, and (3) in fell-fields that contained plant patches (Azorella selago, Colobanthus kerguelensis, or Lycopodium magellanicum and/or bryophytes). Our study is expected to facilitate the implementation of biosecurity measures to mitigate accidental introduction of M. soledadinus to pristine areas that it has not yet colonized.