Abstract
AbstractThe discovery of deep-sea hydrothermal vent fauna, kilometers deep in the oceans, is a great achievement of 20th-century marine biology. The deep-sea hydrothermal food web does not directly depend on the sun energy. Vent communities rely primarily on trophic associations between chemoautotrophic bacteria and consumers. A small number of endemic taxa are adapted to this highly toxic environment distributed along ridge crests. Where they appeared and how they dispersed is among the important questions ecologists must answer. Here, by statistical analysis of the most comprehensive data base ever assembled about deep-sea hydrothermal fauna, we delineate six major hydrothermal provinces in the World Ocean, then we identify five significant dispersal flows between adjacent provinces and derive a hypothesis about the center from which that fauna has dispersed to the oceanic ridges of the world. Our data-driven conclusion can be tested by phylogenetic studies and completed by surveys of less explored fields.
Highlights
Discovered in 1977 at 2500 meter depth on the Galapagos Spreading Centre, deep-sea hydrothermal vent communities have been located and studied over different geological and dynamic environments: fast to slow-spreading mid-oceanic ridges, back-arc basins, volcanic arcs, and active seamounts
Given the considerations outlined in the Introduction, we can consider these clusters as biogeographic provinces, with the understanding that these preliminary provinces may be split in the future when more vent fields have been explored
Five arrows originated in the Northern East Pacific Rise (NEPR), pointing towards the Northeast Pacific (NE), the Northwest Pacific (NW), the Southwest Pacific (SW), the Southern East Pacific Rise (SEPR), and the Northern Mid-Atlantic Ridge (MAR)
Summary
Discovered in 1977 at 2500 meter depth on the Galapagos Spreading Centre, deep-sea hydrothermal vent communities have been located and studied over different geological and dynamic environments: fast to slow-spreading mid-oceanic ridges, back-arc basins, volcanic arcs, and active seamounts. A large majority (82% according to McArthur and Tunnicliffe, 1998) are unrecorded from other marine settings and have been described as specialized or “endemic” to these toxic, unstable and patchy environments. This endemicity at the species level has been debated since the discovery of hydrothermal vents. Recent studies suggest that the end-Cretaceous extinction event, and the earlier anoxic/dysoxic events, had no significant influence on deep-sea vent and seep taxa (Kiel and Little, 2006). Biogeographic factors (physical barriers and corridors) that contribute to the isolation of vent faunas on different ridge segments or complexes may yield different, separately evolved sets of species filling the same niches (Tunnicliffe et al, 1996; Tunnicliffe et al, 1998) and cause isolation of species groups by the process of vicariance
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