02709nas a2200241 4500008004100000245010000041210006900141260001200210300001400222490000700236520190500243100001802148700002202166700002002188700001702208700002202225700001302247700002402260700002202284700002402306700002302330856011402353 2008 eng d00aEffects of Human Trampling on Populations of Soil Fauna in the McMurdo Dry Valleys, Antarctica.0 aEffects of Human Trampling on Populations of Soil Fauna in the M c12/2008 a1544-15510 v223 a

Antarctic ecosystems are often considered nearly pristine because levels of anthropogenic disturbance are extremely low there. Nevertheless, over recent decades there has been a rapid increase in the number of people, researchers and tourists, visiting Antarctica. We evaluated, over 10 years, the direct impact of foot traffic on the abundance of soil animals and soil properties in Taylor Valley within the McMurdo Dry Valleys region of Antarctica. We compared soils from minimally disturbed areas with soils from nearby paths that received intermediate and high levels of human foot traffic (i.e., up to approximately 80 passes per year). The nematodes Scottnema lindsayae and Eudorylaimus sp. were the most commonly found animal species, whereas rotifers and tardigrades were found only occasionally. On the highly trampled footpaths, abundance of S. lindsayae and Eudorylaimus sp. was up to 52 and 76% lower, respectively, than in untrampled areas. Moreover, reduction in S. lindsayae abundance was more pronounced after 10 years than 2 years and in the surface soil than in the deeper soil, presumably because of the longer period of disturbance and the greater level of physical disturbance experienced by the surface soil. The ratio of living to dead Eudorylaimus sp. also declined with increased trampling intensity, which is indicative of increased mortality or reduced fecundity. At one site there was evidence that high levels of trampling reduced soil CO2 fluxes, which is related to total biological activity in the soil. Our results show that even low levels of human traffic can significantly affect soil biota in this ecosystem and may alter ecosystem processes, such as carbon cycling. Consequently, management and conservation plans for Antarctic soils should consider the high sensitivity of soil fauna to physical disturbance as human presence in this ecosystem increases.

1 aAyres, Edward1 aNkem, Johnson, N.1 aWall, Diana, H.1 aAdams, Byron1 aBarrett, John, E.1 aBroos, E1 aParsons, Andrew, N.1 aPowers, Laura, E.1 aSimmons, Breana, L.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/effects-human-trampling-populations-soil-fauna-mcmurdo-dry-valleys-antarctica02560nas a2200205 4500008004100000245008000041210006900121300001200190490000700202520193000209653001102139100002202150700002002172700002302192700002202215700001302237700001802250700001702268856006902285 2006 eng d00aWind dispersal of soil invertebrates in the McMurdo Dry Valleys, Antarctica0 aWind dispersal of soil invertebrates in the McMurdo Dry Valleys  a346-3520 v293 a

Dispersal of soil organisms is crucial for their spatial distribution and adaptation to the prevailing conditions of the Antarctic Dry Valleys. This study investigated the possibility of wind dispersal of soil invertebrates within the dry valleys. Soil invertebrates were evaluated in (1) pockets of transported sediments to lake ice and glacier surfaces, (2) wind-transported dust particles in collection pans (Bundt pans) 100 cm above the soil surface, and (3) sediments transported closer to the surface (<50 cm) and collected in open top chambers (OTCs). Invertebrates were extracted and identified. Nematodes were identified to species and classified according to life stage and sex. Three species of nematodes were recovered and Scottnema lindsayae was the most dominant. There were more juveniles (∼71%) in the transported sediments than adults (29%). Tardigrades and rotifers were more abundant in sediments on lake and glacier surfaces while nematodes were more abundant in the dry sediment collections of Bundt pans and OTCs. The abundance of immobile (dead) nematodes in the Bundt pans and OTCs was three times greater than active (live) nematodes. Anhydrobiosis constitutes a survival mechanism that allows wind dispersal of nematodes in the McMurdo Dry Valleys. Our results show that soil invertebrates are dispersed by wind in the Dry Valleys and are viable in ice communities on lake surfaces and glaciers.

10aBiggie1 aNkem, Johnson, N.1 aWall, Diana, H.1 aVirginia, Ross, A.1 aBarrett, John, E.1 aBroos, E1 aPorazinska, D1 aAdams, Byron uhttp://link.springer.com/content/pdf/10.1007%2Fs00300-005-0061-x