Species diversity and random distribution of microfauna in extremely isolated habitable patches on Antarctic nunataks
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Populations of metazoan microfauna (nematodes, rotifers and tardigrades) are patchily distributed on mountain outcrops penetrating the ice sheet (nunataks) in continental Antarctica. The abundance and fauna composition of microscopic animals vary greatly also among samples from similar types of habitats. Occurrence of similar seemingly habitable sites without microfauna and sites with various combinations of animal taxa indicates that stochastic colonization processes as well as local environmental factors and historical factors influence faunal composition in a specific habitable patch. The abundance of nematodes, rotifers and tardigrades in various combinations of co-occurrence was analyzed. One objective was to investigate if biotic interactions structuring these simple communities could be observed. The 368 samples analysed originate from three kinds of habitats, viz. mosses, ornithogenic soils and fellfield soils, obtained from 14 nunataks in Dronning Maud Land, East Antarctica. It is suggested that high population densities of any of the three animal groups, when they were found alone and lower densities, when they coexisted with other taxa could indicate the presence of competition or predation. However, the great variability in microfauna densities for similar habitable patches made it difficult to find significant differences among population densities in samples with varying complexity.
KeywordsAntarctic nunataks Competition Fellfield Moss Nematodes Ornithogenic soil Predation Rotifers Tardigrades
We are grateful to the Swedish Polar Research Secretariat for providing transport and facilities for K. Ingemar Jönsson, who conducted the field sampling in Antarctica in 2001/02; for Cecilia Eriksson, who made the sampling in 1993/94 and 1996/97 and for Göran Thor, who made the sampling in 1991/92. Kent Larsson is thanked for providing the map. Ingegerd Sohlenius is thanked for technical assistance. Helpful comments on the manuscript were given by two anonymous referees.
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