High-resolution monitoring of long term changes in physical limnology in the McMurdo Dry Valleys, Antarctica

In the McMurdo Dry Valleys of Antarctica, permanently ice-covered, closed basin lakes are the terrestrial endpoints of hydrologic flow in the watersheds, and are therefore excellent indicators of greater catchment processes. In this remote and harsh environment, most ecosystem studies have been based on limited sampling initiatives carried out during the Antarctic summer; the period of the year when the lakes receive the majority of annual solar radiation and nutrient input. However, as the sole repositories of liquid water during the Antarctic winter, it is likely that we have underestimated the ecological complexity of the Dry Valley lakes year-round. As part of the McMurdo Dry Valleys LTER, we have two overarching goals. The first is to monitor year-round temporal changes in the physical properties of the lake ice and water column in order to establish a longterm dataset to understand climatic and hydrologic variability in the Dry Valleys. Measurements include lake level, ablation, underwater radiation, and ice thickness. Currently, we are equipping all monitoring sites with telemetry to allow real-time data retrieval during the Antarctic winter. The second goal is to investigate the physical characteristics of the lakes in high- resolution spatial detail. In West Lake Bonney, this was accomplished through the deployment of ENDURANCE, an autonomous underwater vehicle that was capable of generating 3D biogeochemical datasets, high-resolution bathymetric and ice thickness maps, and imaging the underwater face of Taylor Glacier. It is hypothesized that climate warming in Antarctica will amplify water and nutrient cycling between glaciers, rivers, and lakes, and increase biodiversity and productivity throughout the ecosystem. Since 2001, we have seen evidence of enhanced connectivity, as lake levels have rapidly risen in response to greater fluvial inputs. Analyses of our long term datasets, in collaboration with researchers who monitor other watershed processes, enable us to investigate the larger processes that are controlling the rise in lake levels, changes in the ice cover, and the physical hydrology of the lakes.