THE REAL RIVER STYX: THE KARST-CONTROLLED BIOGEOGRAPHY OF SUBSURFACE LIFE?

Earth's subsurface lithosphere has a highly complex hydrology, a rich biodiversity of microorganisms largely unknown until the past few decades, and higher life forms of unique characteristics that are understudied and poorly understood. How do all of these organisms reach the subsurface? Is there a permanent, indigenous pool of microbial forms that comprise a lithospheric biosphere? These ecological communities must somehow move and distribute themselves in Earth's subsurface. Water in all its forms provides the transport mechanisms. These range from underground streams to the monomolecular water layers around individual grains in sedimentary facies. Impermeable strata, igneous intrusions and the like perhaps may serve the same biogeographic isolation functions that mountain ranges, deserts, and oceans do in Earth's surface biosphere. The highly fractured, orthogonal topology of karst may provide "organism superhighways" that can produce surprising connections for subsurface organisms to reach new terrain. The complexities of these water-borne organism distribution patterns are virtually untouched as a research problem. Karst water studies can illuminate the distributions of subsurface organisms. In turn, organisms can serve as tracers in hydrological investigations. Together they could comprise a fruitful new blending of disciplines brought to bear on a unique topic of investigation.