During the 2010/2011 Exploration vessel Nautilus expedition to the Mediterranean Sea, samples of Lamellibrachia (Siboglinidae, Annelida) were imaged in situ and collected from hydrothermal vent and methane "cold seeps." An analysis of these Lamellibrachia and their endosymbiotic thioautotrophic gammaproteobacteria reveals two distinct endosymbiont phylotypes. Phylotype 1 was present in Lamellibrachia specimens from 947 m at the Eratosthenes seamount seep (a seep off Cyprus in the Eastern Mediterranean), and Phylotype 2 was found in siboglinids from 618 m at a hydrothermal vent within Palinuro volcanic complex in Tyrrhenian Sea. Both phylotypes coexist in siboglinids at 1,036 m from the Palmachim disturbance, a cold seep in the Eastern Mediterranean's Levantine basin. Our results, combined with existing knowledge of siboglinid host and endosymbiotic bacteria biogeography, reveal that two major groups of endosymbionts coexist within lamellibranchids and escarpids. The phylogenetic clustering of these bacteria is primarily influenced by geographic location, rather than selection by the siboglinid host.
Bibliographical noteFunding Information:
Acknowledgments We thank the european Commission FP7 research infrastructure initiative program, “assemble 227799,” for partial support of this project. This research used samples and data provided by the e/V Nautilus exploration Program—expeditions na008, na009, na015 and na019. The authors would like to thank all individuals who helped during the expedition, including onboard technical and scientific personnel, and the captain and crew of the e/V Nautilus.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science