Recruitment variation during a pilot colonization study of hydrothermal vents (9°50′N, East Pacific Rise)

Colonization of basalt plates deployed by submersible was measured in a three-year pilot study at hydrothermal vents near 9°50′N on the East Pacific Rise. Most species and speciesgroups were capable of colonizing plates in both warm (diffuse vent flows of up to 25°C) and cool (no detectable temperature anomaly) zones. The discovery of numerous protoconch-stage recruits of the limpet Lepetodrilus elevatus on basalt plates in both warm and cool zones, and in two study sites separated by >1 km, indicated that a very recent, regional settlement event had taken place. Size distributions of the L. elevatus colonists suggest a previous distinct recruitment event also may have taken place during the three-year interval. Of the prominent vent taxa whose adult distributions were known, a few colonized only the zones inhabited by adults (the scallop ?Bathypecten, the polychaete Paralvinella, and vestimentiferan tubeworms), but two others colonized outside the adult ranges (the bivalve Bathymodiolus, and the polychaete Laminatubus). (Taxonomic uncertainties have been denoted by “?”.) The results suggest that both temporal variation in recruitment and post-settlement biological interactions are important in structuring communities at hydrothermal vents.