The history of perennially ice covered lakes in the McMurdo Dry Valleys (MCM), Antarctica have been extensively studied under the Long Term Ecological Research (LTER) project. The lakes are formed in endorheic basins enclosed by topographic relief or glaciers. Over the past century, the lakes have experienced an overall trend of continuous lake level rise despite decrease in solar radiation (Doran et al, 2002). Variability/increase of lake levels is caused by the sole water source; melt from nearby glaciers during austral summer months.

Palmer LTER has as its focus the marine continental shelf and marginal sea ice zone ecosystems off the west coast of the Antarctic Peninsula. It is a marine pelagic and coastal site strongly influenced by the formation, extent, duration and retreat of sea ice. Over the past several decades sea ice duration has declined by 90 days and no longer persists into the summer period in our study region. At the same time, the mean wintertime (DJF) surface air temperature has increased by 6°C.

Permafrost plays an important role in shaping the chemistry of streams by restricting subsurface flows through catchments to soils. During the summer thaw of soil, subsurface flows migrate through deeper soil horizons presumably resulting in seasonal shifts in the inputs of carbon and nitrogen to the streams. Within streams, the extent of the hyporheic zone may also shift with seasonal thaw. Hyporheic zones have high mineralization and nitrification rates; thus expansion of the hyporheic zone throughout the season has important implications for stream chemistry.