WOOD FALLS, COLD SEEPS, AND IMMIGRATION INTO TRANSIENT DEEP-SEA HABITATS

Sunken drift wood, whale carcasses, hydrocarbon seeps, and hydrothermal vents in the deep-sea are transient oases of food on the otherwise barren seafloor. They harbor unique and largely endemic faunal communities, and the origin of these faunas has been under debate since they were discovered in the 1970's and 80's. The fossil record shows that most of the taxa living at vents and seeps today arrived there during the last 150 Million years. Quantitative and qualitative analyses of the fossil record indicate continuous immigration into these extreme environments, however, it also shows periods of increased rates of immigration and quiet times of little immigration. The Albian and the Late Eocene-Oligocene might represent periods of increased immigration, and very few new taxa appeared after the Oligocene. These patterns are compared to global events including climate changes, sea level fluctuations, and anoxia. Contrary to previous suggestions, oceanic anoxic events seem to have had little effect on the evolutionary history of vent and seep faunas; only the Aptian/Albian boundary event might have caused minor extinctions. New data especially on fossil wood-fall communities are used to assess the role of these habitats as possible stepping stone for vent and seep taxa.