Antarctic Dry Valley Nematode Communities: Establishment, Function and Response to Disturbance

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9624743 Freckman Nematodes, microscopic roundworms, are among the most complex animals capable of survival in the soils of the Antarctic Dry Valleys. If dispersal of nematodes to habitats is uniform and unlimited by geographical constraints, communities of nematodes could potentially establish in all soils of the Dry Valleys of Antarctica, as they do in other ecosystems studied. Nematode distribution in the Dry Valleys is patchy. It follows that dispersal rates are low, or the establishment of nematode communities is governed by the suitability of potential habitats and the ability of nematodes to survive harsh environmental conditions. Habitat suitability may be defined by such factors as carbon availability or salinity. This research project is organized around central hypotheses that move from individual to ecosystem scales in order to understand how nematodes disperse, survive, and develop functional communities in Antarctic Dry Valley soils. The hypotheses are: (1) nematode community function is more influenced by desiccation than temperature, and (2) habitat suitability, not dispersal, is the major factor determining establishment and maintenance of nematode communities in the Dry Valleys. To test these hypotheses, field work will be conducted to examine the characteristics of habitats that appear suitable for nematode community growth and establishment by sampling from a variety of sites, encompassing a wide range of salinities, moistures, and carbon contents. Stable isotope studies (C and N) will provide information on sources of C entering soil ecosystems and supporting nematodes. Dispersal will be examined with traps in the field, and molecular techniques in the laboratory to investigate the genetic variability that exists between widely distributed nematodes with similar morphological characteristics. The survival strategies of nematodes will be examined under field and laboratory conditions to better understand how these animals are able to p ersist under harsh climatic conditions. In addition, the soil food web serves as a sensitive indicator of environmental change, particularly in this ecosystem, where biodiversity is low and resource allocation is primarily invested in survival. Any knowledge about the degree of influence of such change, as well as the influence of various physical and chemical soil characteristics, can ultimately extrapolated to other environments.