Microhabitats occupied by terrestrial arthropods in the Stillwell Hills, Kemp Land, East Antarctica

Abstract

A fine-scale survey of the distribution of free-living terrestrial arthropods in the Stillwell Hills region of Kemp Land, East Antarctica, was carried out between 22 December 1996 and 27 January 1997. Three species, all Acari, were recorded: Protereunetes maudae Strandtmann, Nanorchestes triclivatus Booth and N. lalae Strandtmann. Population densities varied from 0 to 6802 ind. m⁻² with a mean of 954 ind.m⁻². The favoured microhabitat was found to be beneath stones in damp locations on north- and west-facing slopes. Sites with microalgal growth supported more microarthropods than sites with mosses, lichens and macroalgae. Arid and saline habitats, including such sites as wind-sweptridges and the seashore, were found to lack microarthropods. Thermal and humidity profiles above and below the ground surface were recorded to investigate the microenvironments of Acari. Special attention was focused upon the moderating role of snow thickness, vegetation cover, aspect and vertical depth in the soil profile. These microclimate data suggest that Acari are able to avoid the extremes of low temperature experienced at macroclimate level but that heat stress and desiccation may play important limiting roles.