Specific and genetic diversity at deep-sea hydrothermal vents: an overview

Hydrothermal vent communities are ancient (i.e. early Mesozoic) and characterized by high biomasses, low number of species and high levels of endemism. However, little is known about the ecology and behaviour of the vent macro-and megafauna. Data on the biology and the life-history of hydrothermal-vent organisms are scarce and lead us to hypothesize various ways in which such species disperse and colonize their habitat. Such biological and ecological patterns are important for assessing both the spatial and temporal distribution of the vent fauna and the evolution of such peculiar species with geological times and, therefore need to be reviewed. Scattered information referring to vent-site distribution, bottom currents, temporal evolution of the vent emissions and their implication on the related fauna have been accumulated over the last decade. To date, several ecological and genetic studies have attempted to analyse vent fauna structures to understand how populations and communities evolve with time in such a patchy and unstable environment. They also provide faunistic comparisons across the vent communities discovered so far on well-separated oceanic ridges. This article provides a synthetic overview on biodiversity in deep-sea hydrothermal vents, genetic diversity of hydrothermal-vent species and factors responsible for similarities or differences among the vent fauna within and between well-separated venting areas of the Atlantic and Pacific ridges.