Climate-driven hydrological connectivity alters littoral and ice-covered ecosystems of Antarctic lake margins

Climate-driven glacial melt is altering polar ecosystems. Shifts in hydrological regimes have cascading effects on limno-terrestrial ecosystems. In the McMurdo Dry Valleys (Southern Victoria Land, Antarctica), year-round ice cover isolates lentic habitats, yet seasonal melt along the lake perimeter forms open-water “moats” during the short austral summer provide transient hydrological connectivity among soils, benthos, and the stratified water columns of the dry valley lakes. To investigate how connectivity influences biological communities, we tracked biodiversity, phytoplankton photosynthesis, and physicochemistry along lateral transects in two McMurdo Dry Valley lakes, Fryxell and Bonney. These lakes, shaped by distinct basin features (bathymetry, streams) and ecological legacies (nutrient status, chemistry), exhibited contrasting degrees of limno-terrestrial connectivity. Our data reveal that lake-specific hydrological linkages restructure microbial and invertebrate communities. We conclude that climate-induced hydrological changes destabilize previously stratified systems, altering ecological interactions and fundamental ecosystem processes across Antarctic limno-terrestrial ecosystems. Our findings provide critical insight into how polar freshwater ecosystems may reorganize under future climate scenarios, informing predictions of microbial community resilience in extreme environments.