Export of deep-sea hydrothermal particles, indigenous thermophilic microorganisms and larvae to the surrounding Ocean

Abstract : To assess the production and the export of particulate and biological material in deep-sea hydrothermal vents, four moorings with sediment traps and current meters were deployed for 24 days in the Azores Triple Junction (ATJ) region. They were deployed along an axis starting at the base of a hydrothermal vent chimney and ending 1000 m away. The particles sampled at the base of the chimney were characterized by high concentrations in total sulfur (16%) and iron (4%). The particle composition changed drastically with distance from the vent: the sulfur concentration decreased with an increase in clay components. Thermophilic microorganisms were successfully enriched from all the particle samples. Cultured strains were closely related to hydrothermal species, suggesting that viable hydrothermal vent microorganisms can be exported easily from one hydrothermal field to the open ocean. Fauna collected in the trap at the base of the chimney also included the hydrothermal mytilid species Bathymodiolus azoricus (prejuvenile prodissoconch late stage), larval or juvenile polychaetes and two vent gastropod species (Shinkailepas sp. and Phymorhynchus sp.). These organisms were not sampled by the others sediment traps. The most common taxa found in the traps off the vent were polychaetes, euphausiaceans and copepods (harpacticoids, nauplii and calanoids).