Abstract :
In this review we consider the physical processes that shape inland aquatic ecosystems and how
these affect ecosystem processes, with particular focus on the nitrogen cycle. Inland Antarctica is dominated
by microbial communities that are usually concentrated in, or adjacent to, habitats with free water. The
presence of free vs frozen water is dependent on very small changes in temperature around 0ºC, so
significant variability in the distribution of free water can be expected in response to variations in climate
over diel, decadal, to millennial time scales and a range of spatial scales. Antarctic inland waters take many
forms: snow-surface melt pockets, cryoconites, basal regions of wet-based glaciers, ponds (varying in
salinity and degree of desiccation), melt streams, perennially and seasonally ice covered lakes and even
hypersaline, ice free lakes. The important processes and transformations that characterize the nitrogen cycle
worldwide have all been identified in Antarctic inland waters and in some cases (e.g. N-uptake, N-fixation),
rates are similar to those at lower latitudes. The unique features of Antarctic ecosystems stem from the
extreme and variable physical conditions under which these processes operate rather than any unique
ecosystem processes per se.
