Determining habitat suitability for soil invertebrates in an extreme environment: the McMurdo Dry Valleys, Antarctica

We sampled soils in the McMurdo Dry Valleys to determine the habitats that were suitable or extreme for soil invertebrates. Suitability was assessed by comparing nematode species diversity and abundance, and tardigrade and rotifer abundance as related to soil properties at three spatial scales: landscape (across Taylor, Wright and Victoria valleys), at three distant locations within valleys, and within small plots (1 m(2)). Extreme environments were characterized by the lack of nematode abundance and diversity, high salinity, low soil moisture and organic carbon, and higher elevation or a geographic location less accessible for dispersing organisms. Suitable habitats were more frequent near the coast and at lower elevations. Extreme habitats could be defined based on one environmental factor, but more typically a set of interrelated soil and environmental factors appear to determine the abundance and composition of the soil community. The three Dry Valley nematode species occupied distinct regions of a multivariate biplot relating soil chemistry and moisture. Scottnema lindsayae is unusual for its ability to live in a wide range of extreme soil habitats. Our research shows that in the McMurdo Dry Valleys, life flourishes in suitable soil habitats and that extreme habitats ("no invertebrates") call be defined.