The hydrothermal vent community of a new deep-sea field, Ashadze-1, 12°58′N on the Mid-Atlantic Ridge

Abstract

The study focuses on the question, how a seamount in the oligotrophic eastern Mediterranean affects the zooplankton community, as compared to the open water. Zooplankton samples were taken with 333 mm nets at two sites, the Rhodes Basin and the Anaximenes Mountain, in December 2006. The samples were sieved into size fractions, and the composition, biomass, abundance and stable isotope signatures were analysed. In general, biomass and abundance of zooplankton were low, reflecting the oligotrophic character of the eastern Mediterranean, but zooplankton standing stocks were higher at the Rhodes Basin than at the Anaximenes Mountain. Stable isotope signatures showed, at a generally low level, enrichment in zooplankton taxa along the food chain within the different pelagic zones and from the surface to the deep-sea, but no significant differences between Rhodes Basin and the seamount were evident in the food web structure. The zooplankton community in the Anaximenes Mountain region in the northern Levantine Basin seems not to be influenced by a local seamount effect, despite the difference in standing stocks between the seamount and the Rhodes Basin. This seems to be driven by larger-scale upwelling and downwelling structures of cyclones and anticyclones, dominating the circulation in the area.

Acquisition of epibiotic bacteria along the life cycle of the hydrothermal shrimp Rimicaris exoculata

“…Bacteria within the gill chamber could have roles such as detoxication or nutrition for the host (Zbinden et al, 2004. The Ashadze and Logachev sequences clustered together (Figure 3b, clusters 3 and 6), which might be explained by the very close proximity between these two sites (Fabri et al, 2011). A recent study showed a significant correlation between genetic (16S rRNA) and geographic distances for R. exoculata epibionts along the MAR .…”

“…Surprisingly, the Ashadze fauna was dominated by species usually recovered at the periphery of hydrothermal communities (Maractis rimicarivora and Phyllochaetopterus sp. nov.) (Fabri et al, 2011). All the collected shrimps were alive and active when recovered from the slurp gun bowls, but the Ashadze specimens were less active than the other sites.…”

Elucidating trophic pathways in benthic deep-sea assemblages of the Mid-Atlantic Ridge north and south of the Charlie-Gibbs Fracture Zone

“…This ac cords with the range of δ (Erickson et al 2009). This is pertinent on MOR where vent organic matter entrained in hydrothermal plumes can be found settling 2 km away from the venting source (Roth & Dymond 1989), bathypelagic biomass in association with the hydrothermal plume can be enhanced (Burd et al 1992) and consumers at inactive chemosynthetic sites can potentially utilise organic sulphur compounds derived from sulphide of hydrothermal vent origin that has persisted within the sediment (Erickson et al 2009 S values between −9 and 10 ‰ (Erickson et al 2009, Fabri et al 2011. The MAR consumers fall within the former range, confirming these stations were dependent on photosynthetic primary production and not influenced by unknown chemosynthetic sources that were transported to or persisted within the sediment.…”

Picturing thermal niches and biomass of hydrothermal vent species

“…Kim and Hammerstrom, 2012;Lutz et al, 2008;Sen et al, 2013;Urcuyo et al, 2003), Atlantic (e.g. Copley et al, 2007Copley et al, , 1997Fabri et al, 2011;Sarrazin et al, 2015;Van Dover and Doerries, 2005), and Indian (e.g. Van Dover et al, 2001) oceans.…”