A review of predators and predation at deep-sea hydrothermal vents

The very few predators at deep-sea hydrothermal vents have been hypothesize d to allow extremely vulnerable, relic taxa to survive in these habitats. I f vents are viewed as ephemeral habitats in which disturbance is so frequen t that few endemic predators can survive, their scarcity, rather than being an anomaly, is seen as a logical consequence of habitat transience. Toxins , however, may minimize exploitation of the habitat by most opportunistic p redators. Rates of lethal predation remain undetermined, but vent limpets and vestime ntiferans, including those from areas with high sulphide levels, show frequ ent evidence of non-lethal predation. Characterizing vent habitats as unchanged over geological time and as home to "relic" taxa of ancient groups ignores historic anoxic episodes and the increasing fossil history of vent assemblages. Although trophic relations o f vent predators remain poorly known, deep-sea predators are more diverse b oth taxonomically and in their foraging habits than had been expected; the reportedly vulnerable vent fauna may show unsuspected defenses. Variation in Carbon and Nitrogen isotopes among chemosynthetic taxa and bac teria complicates isotope analyses which are most powerful when supplemente d by direct observations and specimen-based documentation of prey. Technolo gical advances offer new promise for these analyses.