Impacts of thawing permafrost on nematode populations and soil habitat characteristics in an Antarctic polar desert ecosystem

• Main Author: Smith, Tracy
• Format: Thesis
• Language: English
• Published: Colorado State University 2011
• Subjects: Ecology; Antarctic; McMurdo Dry Valleys; Antarc*; Antarctica; Ice; permafrost; polar desert
• Online Access: http://pqdtopen.proquest.com/#viewpdf?dispub=1499743

Global climatic changes are altering ecosystem dynamics at unprecedented rates and degrees. Given this, studying the controls on species distribution and functioning within ecosystems, as well as how they are impacted by such changes, is timely. Polar deserts such as those in the McMurdo Dry Valleys, Antarctica (MDV) have been exposed to long-term cooling over the last two decades as well as increased frequency of seasonal warming events, and may also be exposed to a warming trend within the next several decades. Each of these changes can lead to substantial shifts in ecosystem characteristics, affecting habitat conditions for biota. I examined these issues with a specific focus on how nematode communities, the dominant fauna in the extremely cold and arid environment of the MDV, responded to a warming event that led to inundation of moisture from thawing permafrost. I took samples to the depth of the ice-cemented soil layer in seeps of permafrost thaw and compared nematode community structure to dry soils not affected by thaw. I also assessed potential alterations to soil properties that determine suitability of nematode habitats, measuring soil pH, salinity, and texture. I observed a gradient in impacts on each of these soil properties, which were consistent with the pattern of the degree of moisture increase. I additionally observed a response by nematode populations that similarly followed these patterns. My results suggest that warming and the resulting moisture increases from thawing permafrost can have profound negative effects on nematode abundance and distribution.