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Contributed Poster

Session: Soil

PS 47-208 - The warmest March: soil biota response to an extreme warm weather event in the McMurdo Dry Valleys, Antarctica

Wednesday, August 9, 2023
5:00 PM – 6:30 PM PDT
Location: ESA Exhibit Hall
Abstract: As climate change influences the distribution and activity of organisms worldwide, it is important to monitor the life history of populations in harsh environments that are highly sensitive to extreme weather events. The McMurdo Dry Valleys (MDV) of Antarctica are an environment where the cold and arid conditions limit soil communities to a few taxa of invertebrates, including 3 genera of nematodes: Scottnema; Eudorylaimus; and Plectus. These taxa are adapted to survive freezing temperatures and extreme desiccation of soil, but vary in their distribution across the landscape relative to soil geochemistry and moisture availability. For example, the endemic species Scottnema lindsayae prefer saltier, drier soils whereas Plectus murrayi are typically found in wetter soils along the aquatic margins of streams and lakes. In 2022, the MDVs experienced the warmest March temperatures on record with a high of 6.74°C on March 18th. This occurred when soils and sediments were already frozen, and organisms were in cryo-preserved states in anticipation of the Austral Winter. Based on changes in surface liquid water content captured by remote sensing on 14 March, 2022 and 20 March, 2022; this temperature increase created a significant thaw event within the Canada Stream Antarctic Specially Protected Area of Taylor Valley. The goal of this study was to determine the impacts of this extreme weather event on soil biota abundance, diversity, and life history. To accomplish this, sampling coordinates were selected from remotely sensed data to include locations with little to no evidence of change in liquid surface water content and sites with a significant change in liquid surface water content. We found that soil moisture positively correlated with Simpson’s Diversity Index (1/D) across all samples (R2=0.50) and that the driest sites supported the lowest abundance and diversity of soil invertebrates. Wetted soils had a higher mortality of Scottnema, Eudorylaimus, and Plectus spp. than dry sites, and Scottnema and Plectus demonstrated higher fecundity in wetted soils than dry soils, suggesting that the thaw event influenced the activity and life history of these soil communities. This study contributes to our knowledge of invertebrate species distribution and community changes within the MDV and how they might be shifting due to global change, such as increasing moisture levels after warm weather events.