Vent systems are the perfect laboratory. This means we must examine the extremes. We know little about survival strategies of extremophiles. In deep terrestrial basalt formations, microorganisms persist indefinitely without organic carbon from the surface. Physically, sea-ice varies from fine ice particles suspended in water to thick blocks of ice hundreds of meters across.
Sea ice is colonized internally by many microorganisms.
Collectively they support krill and a complex and diverse marine community. Survival strategies of the microorganisms, which are trapped below freezing in sea-ice brine during the long, dark, winter, have not yet been studied well. We hypothesize that fluid mineral content and sub-zero temperature drove evolution of novel survival strategies. This could occur on other volcanically active planetary bodies. By studying the physiological attributes and cellular strategies for survival at temperature extremes beyond those currently believed to support life, we expect to develop models and predictions of the boundaries of life in a tectonically active subsurface regime.