Coupled climate and earth-system models predict increased temperatures and altered precipitation patterns in vast regions of Maritime and coastal Continental Antarctica, which will likely result in more extensive glacial melt and the expansion of ice-free areas, increasing connectivity between regions, and changes in their hydrology. Terrestrial and lacustrine biota in the Antarctic are more globally distinct and biogeographically structured than previously believed. These observations come from recent evidence of high levels of endemism and narrow distributional ranges due to the long-term survival and diversification of taxa in isolated glacial refugia. The effects of these projected environmental changes on terrestrial and aquatic biodiversity are thus likely to cause biotic homogenization between regions, the extinction of certain taxa, and the spread of invasive species.

HabitAnt aims at studying past, present and future habitability of lakes and their catchments in coastal East Antarctica. This will be based on the elucidation of key processes that contributed to their present-day community structure, including long-term persistence of biota in glacial refugia, and extinction, colonization, diversification and biological succession in response to environmental changes during the past 130,000 years. More specifically, we aim to (1) identify the presence of local glacial refugia including those situated below present-day sea level, (2) infer the recent evolutionary history of selected key lacustrine and terrestrial Antarctic biota in different functional and taxonomic groups, (3) assess species assembly and biological succession in newly formed lakes after deglaciation and their response to climate warming, and (4) use this paleoecological information, in combination with existing inventories of recent distribution data, to predict the response of these communities to future climate changes.

Our studies will be based on well-dated lake sediment cores from three regions in Continental Antarctica with a contrasting deglaciation history. We will analyse ancient DNA (aDNA), microfossils and a suite of sedimentological and biogeochemical proxies, including a quantitative paleotemperature proxy based on glycerol dialkyl glycerol tetraether (GDGT) membrane lipids and fossil photosynthetic pigments. We will focus our paleoecological analyses on three time windows, namely the Eemian interglacial, the last glacial period, and the Holocene. The aDNA and microfossil data will be dovetailed with extensive, recently developed datasets of present-day lacustrine communities in the Antarctic biogeographic realm. This will allow us to study the potential colonisation of taxa currently thriving in the sub-Antarctic and Maritime Antarctica into the Continental Antarctic ice-free oases during warm periods. Extinctions and survival of taxa during the last glacial period will be studied in sediments spanning the Eemian to Holocene interglacials. In combination with studying submarine basins containing Late Pleistocene and Early Holocene terrestrial and paleolake sediments, this will enable us to identify the presence of local (hidden) glacial refugia. Phylogenetic molecular clock analyses of selected cyanobacteria, protists and invertebrates will be used to infer their evolutionary dynamics and histories. Combined, these datasets will allow us to model the optimum and tolerance of key taxa for temperature and other relevant environmental conditions in Antarctic lakes. These data will be useful to design conservation strategies for Antarctic biodiversity.