The biology, life cycle and ecophysiology of the Antarctic miteAlaskozetes antarcticus

Abstract

The cryptostigmatid mite Alaskozetes antarcticus (Michael) is a dominant member of many terrestrial communities in the maritime Antarctic, where it survives extreme temperatures, short cold summers, numerous freeze-thaw cycles, desiccating conditions and a limited season for growth and reproduction. However, examination of features of its biology, from morphology, through life-history strategy to physiology, indicate very little specialization to the Antarctic environment. Alaskozetes antarcticus is a herbivore/detritivore, typical of the Cryptostigmata in general, with low feeding and growth rates, long life span and low reproductive output. Physiological specializations exist in the form of low enzyme activation energies and elevated metabolic rates at low temperatures when compared with temperate species, and associated low optimum temperatures for activity, feeding and growth. Growth rates comparable with temperate species are achieved in the field, with an extended life cycle of five years or more as a result of the short growing season, and the ability of all life stages to overwinter equally successfully. Overwintering survival, involving supercooling enhanced by the use of antifreezes such as glycerol, although initially described in Antarctic species, is now known to be characteristic of many temperate relatives, so it is not a specific adaptation to the polar environment. The obvious success of A . antarcticus in maritime Antarctic terrestrial environments must be attributed to a combination of several features characteristic of the Cryptostigmata in general, rather than to specific polar adaptations.

Food choice of Antarctic soil arthropods clarified by stable isotope signatures

“…In the absence of autoecological knowledge, such an increase might be used to suggest that Alaskozetes would be a predatory species, or at least forms part of a higher trophic level (Schneider et al 2004). However, existing literature gives no support to the proposal that Alaskozetes would be a predator species (Block 1985;Block and Convey 1995;Worland and Lukesova 2000). Alaskozetes can however, be abundant on and near animal carcasses (Goddard 1982), and feeding on such food sources and excreta may lead to a higher d 15 N signature.…”

“…As there are no large herbivores, almost all this carbon is transferred to the soil (Davis 1981). It has previously been suggested that most of the carbon and nutrients will flow directly into the decomposition pathway without passing through a consumer level (Block 1985). However, the contribution of the dominant groups of soil arthropods, springtails and mites, within these nutrient flows is not well understood.…”

“…Previous studies based on analyses of gut contents have suggested that Cryptopygus feeds on algae, dead organic material, and fungi and thus is an unselective feeder (Tilbrook 1970;Broady 1979;Burn 1984;Block 1985;Cannon 1986). Our results in part support these earlier suggestions, with the caveat that only a limited range of potential sources within each class of food was included in our feeding experiments.…”

Spatial and temporal variability across life's hierarchies in the terrestrial Antarctic

“…Likewise, quantitative ecological work was, until relatively recently, restricted largely to several maritime and sub-Antarctic Islands (see Block 1984;Lewis Smith 1984;Hänel & Chown 1999 for access to this literature), although early work had commenced, but has not been systematically continued, elsewhere (Janetschek 1967). In a similar vein, although more than 27 springtail and 60 mite species have been recorded from the Antarctic continent, comprehensive investigations of the autecology, life histories and environmental responses of these groups have, until recently, been restricted to just a few species, most notably the springtail Cryptopygus antarcticus and the mite Alaskozetes antarcticus (Block 1984;Block & Convey 1995;Convey 1996a).…”

Composición Y Abundancia De La Artropodofauna Terrestre en La Península Fildes

“…La mayor proporción encontrada se explica por la asociación de estos arácnidos con los pingüinos que residen en esta zona protegida (Gressitt et al, 1963). Hasta el momento, Alaskozetes antarcticus intermedius es la especie reportada para el sitio y asociada a las colonias de pingüinos (Block & Convey, 1995). Estudios futuros buscarán determinar los ejemplares para confirmar si se trata de la especie mencionada anteriormente.…”