SPECIFIC AND GENETIC DIVERSITY AT DEEP-SEA HYDROTHERMAL VENTS - AN OVERVIEW

Hydrothermal vent communities are ancient (i.e. early Mesozoic) and ch aracterized by high biomasses, low number of species and high levels o f endemism. However, little is known about the ecology and behaviour o f the vent macro- and megafauna. Data on the biology and the life-hist ory of hydrothermal-vent organisms are scarce and lead us to hypothesi ze various ways in which such species disperse and colonize their habi tat. Such biological and ecological patterns are important for assessi ng both the spatial and temporal distribution of the vent fauna and th e evolution of such peculiar species with geological times and, theref ore need to be reviewed. Scattered information referring to vent-site distribution, bottom currents, temporal evolution of the vent emission s and their implication on the related fauna have been accumulated ove r the last decade. To date, several ecological and genetic studies hav e attempted to analyse vent fauna structures to understand how populat ions and communities evolve with time in such a patchy and unstable en vironment. They also provide faunistic comparisons across the vent com munities discovered so far on well-separated oceanic ridges. This arti cle provides a synthetic overview on biodiversity in deep-sea hydrothe rmal vents, genetic diversity of hydrothermal-vent species and factors responsible for similarities or differences among the vent fauna with in and between well-separated venting areas of the Atlantic and Pacifi c ridges.