Development and characterization of 12 microsatellite markers from the deep-sea hydrothermal vent siboglinid Riftia pachyptila.

Ecological processes at deep-sea hydrothermal vents on fast-spreading mid-ocean ridges are punctuated by frequent physical disturbance, often accompanied by a high occurrence of population turnover. To persist through local extinction events, sessile invertebrate species living in these geologically and chemically dynamic habitats depend on larval dispersal. We characterized 12 polymorphic microsatellite loci from one such species, the siboglinid tubeworm Riftia pachyptila. All loci conformed to Hardy-Weinberg expectations without linkage (mean H(E)  = 0.9405, mean N(A)  = 20.25). These microsatellites are being employed in the investigation of spatial and temporal population genetic structure in the eastern Pacific Ocean.

Vestimentiferan on a whale fall.

Discovery of chemosynthetic communities associated with whale bones led to the hypothesis that whale falls may serve as stepping-stones for faunal dispersal between disjunct hydrothermal vents and cold seeps on the ocean floor (1). The initial observation was followed by a faunal inventory that revealed a diverse assemblage of microbes and invertebrates, supported by chemoautotrophic production, living in close proximity to whale remains (2, 3). To date, the conspicuous absence from whale falls of vestimentiferan tubeworms (a predominant constituent of eastern Pacific vent and seep habitats) has been a major objection to the stepping-stone hypothesis (4-5). We report the first evidence of a vestimentiferan tubeworm associated with a whale fall (Fig. 1). The tubeworm, Escarpia spicata, was identified by morphological criteria and DNA sequence data from a portion of the mitochondrial cytochrome oxidase C subunit I (COI) gene. Additionally, the bacterial endosymbiont in the tubeworm possessed a 16S rRNA gene that was similar to that of endosymbionts from vestimentiferans in sedimented cold-seep environments.