Observations on parasitism in deep-sea hydrothermal vent and seep limpets

Parasite burdens of shallow-water molluscs have been well documented, but little is known about parasite burdens of molluscs from deep-sea chemosynthetic environments (e.g. hydrothermal vents and seeps). Chemosynthetic habitats are characterized by high concentrations of reduced sulfur and, in the case of vents, high heavy metal concentrations. These compounds are noxious and even stress-inducing in some environments, but are part of the natural chemical milieu of vents and seeps. To examine parasite types and infection intensities in limpets from vents and seeps we documented parasite burdens in 4 limpet species from 4 hydrothermal vent fields (3 on the East Pacific Rise, 1 on the Mid-Atlantic Ridge) and 1 seep site (Florida Escarpment). Approximately 50 % of all limpets examined were infected with 1 or more types of parasites. Limpet parasites were predominantly rickettsia-like inclusions in the digestive and gill epithelia. Limpets collected from the vent field on the Mid-Atlantic Ridge were free of parasites. We detected no histopathological effects that we could attribute to parasites.