Interim profile, incomplete information
Details of this species in Sth. Georgia Is. (sub-Antarctic)
Occurrence: Established and expanding
Source: Australian Antarctic Data Centre Undated
Arrival Date: early 1980s
Introduction: Unintentional (accidentally)
Species Notes for this Location:
Trechisibus antarcticus is described as an "invasive alien" in South Georgia by the Australian Antarctic Data Centre (Australian Antarctic Data Centre Undated).
It was reported on South Georgia for the first time in 1982 (Vogel 1985, in Ernsting et al. 1999). From the presumed site of introduction the beetle is invading the coastal lowland area and building up local high densities in the tussock-forming grass Parodiochloa flabellata. Abundance, varying from 2 to 25 individuals per litre of litter, and rate of dispersal show that T. antarcticus is thriving in the coastal lowland areas on South Georgia (Ernsting et al. 1999). Bergstrom & Chown (1999) report that the rapid dispersal of T. antarcticus from its original location in the immediate vicinity of Husvik Harbour into the the Stromness Bay region may have occurred during the warming phase that took place in the sub-Antarctic in the 1980s and 1990s.
Both T. antarcticus and Oopterus soledadinus are common on the Falkland Islands (Roux and Voisin 1982; Robinson 1984), the location from which the whaling stations on South Georgia were mostly provisioned during the period of operation (1910 to 1964) (Headland 1984, in Brandjes Block & Ernsting 1999).
Management Notes for this Location:
Decreases in glacial coverage and increases in temperature associated with climate change are predicted to cause an increase in abundance of Trechisibus antarcticus on South Georgia and resulting changes in the abundance and life-history of native invertebrates (Frenot et al. 2005). Brandjes Block & Ernsting (1999) speculate that further expansion will be limited by geographical features such as glaciers or rocky cliffs without any coastal vegetation (easterly towards Hansen Point) or high and unvegetated mountains (north from Leith and southwest from Husdal towards Gulbrandsen Lake). Suitable habitat available over an extended area in the direction of Carlita Bay may facilitate T. antarcticus to colonise the northern coast of Cumberland West Bay in the future.
Reduction in native biodiversity: In the same coastal areas where T. antarcticus has colonised lives an endemic detritivorous beetle known as Hydromedion sparsutum (Perimylopidae). It is common especially in and beneath the tussock grass. The first three larval instars (stages) of H. sparsutum are easily taken prey by the carabid T. antarcticus. In sites colonised by the carabid, total abundances of larval and adult H. sparsutum are far lower (Ernsting et al. 1999). Preys on the smaller larvae of H. sparsutum has caused decline in abundance and increase in body size of this native beetle (Convey et al. 2006b).
Biotic resistance of the native insect community against the invasion of the carabid is probably weak because of an abundance of prey (such as mites, springtails and small H. sparsutum larvae), and limited inter-specific competition for these resources (Ernsting et al. 1999).
Last Modified: 30/04/2009 11:49:37 a.m.