Low-Diversity Antarctic Soil Nematode Communities: Distribution and Response to Disturbance

Abstract

We are studying the distribution, biodiversity, and abundance of nematodes in the most extreme terrestrial environment on earth, the Dry Valley region of Antarctica. Here we report that the nematode community structure of 1–3 species in two functional groups may be the simplest soil food web of any terrestrial ecosystem. Nematodes were widespread and not correlated with moisture, C, or N, factors that define soil biotic complexity elsewhere. In a field experiment, treatments increasing soil water, carbon, and temperature, alone or in combination, generally decreased the abundance of the single omnivore‐predator species and increased the abundance of its microbivorous prey species. These low‐diversity nematode communities, limited to ≤3 species, apparently lack species redundancy and appear sensitive to environmental change. Our findings suggest that Antarctic soil ecosystems are sensitive to anthropogenic disturbance.

Controls on the distribution of productivity and organic resources in Antarctic Dry Valley soils

“…The last group are the most widely studied (Freckman & Virginia 1997;Treonis et al 1999;Coutright et al 2001;Doran et al 2002). All these consumers form the highest trophic layer in the terrestrial community ('McMurdo's equivalent of elephants and tigers ';Wilson 2002;Wall 2005), and their presence indicates a reliable supply of organic substrates.…”

The effects of prescribed fire on soil nematodes in an arid juniper savanna

“…They are sensitive to different kinds of ecosystem disturbances and soil conditions [1,12,[15][16][17][18].…”

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

“…Antarctic terrestrial diversity lies at the low end of the global spectrum for many, if not most organisms (Convey 2001;Clarke 2003), food webs are typically simple (Block 1984(Block , 1985(Block , 1994Burger 1985;Freckman & Virginia 1997;Wall & Virginia 1999), and life histories tend to be dominated by responses to a seasonally variable, 'stressful' environment (Lewis Smith 1984;Convey 1996a;Vernon et al 1998). Moreover, very little of the largely ice-covered Antarctic continent (0.32% icefree, British Antarctic survey 2004) is available to the terrestrial biota.…”

“…Nonetheless, the determinants of local scale occupancy and abundance have been extensively investigated across a range of sites. Water availability, temperature (which also influences water availability), protection from wind, the availability of nutrients (often nitrogen and also carbon-many continental Antarctic systems are poor in carbon), the extent of lateral water movement, and the extent of soil movement and ice formation all have a pronounced effect on the suitability of sites for colonization, growth and reproduction (Janetschek 1970;Lewis Smith 1984;Ryan & Watkins 1989;Kennedy 1993;Convey 1996a;Freckman & Virginia 1997;Convey et al 2000a;Sinclair 2001;Smith et al 2001). Of these, water availability (and the elevated temperatures that drive it) is thought to be most significant on the Antarctic continent and peninsula, while nutrient availability, soil water movement and temperature are most significant in the sub-Antarctic.…”

“…Notable exceptions are the studies by Usher & Booth (1984, 1986, which appear to have been limited only by the availability of appropriate analytical techniques. Other Antarctic studies have either examined the relationship between abundances and environmental variables directly ( Freckman & Virginia 1997;Courtright et al 2001;Sinclair & Sjursen 2001), or have sought to assess the habitat specificity and fidelity of species without explicit reference to underlying environmental variables (Mercer et al 2000;Barendse et al 2002). However, in a recent investigation of the abundance structure of several arthropod species at Cape Hallett (Northern Victoria Land; , spatially explicit analytical methods were used.…”