Spatial differences in Southern Ocean hydrothermal vent food webs: influences of chemistry, microbiology and predation on trophodynamics.

The hydrothermal vents on the East Scotia Ridge (ESR) are the first to be explored in the Antarctic and are dominated by large peltospiroid gastropods, stalked barnacles (Vulcanolepas sp.) and yeti crabs (Kiwa sp.). Samples were collected at two vent fields (E2, E9) with contrasting vent fluid chemistries to describe trophic interactions and identify potential carbon fixation pathways using stable isotopes. δ13C of dissolved inorganic carbon from vent fluids ranged from -4.6‰ to -2.4‰ at E2 and from -4.4‰ to 0.7‰ at E9. The lightest δ13C in vent macroconsumers were in peltospiroid gastropods (E2 = -30.1‰, E9 = -31.2‰) and indicated carbon fixation via the Calvin-Benson-Bassham (CBB) cycle by a single species of gamma-Proteobacteria housed within the gills. The heaviest δ13C were in Kiwa sp. (E2 = -19.2‰, E9 = -10.6‰), which mirrored that of the epibionts on the ventral setae. Large differences in Kiwa sp. δ13C were potentially the result of site differences in epibiont community (E2 epibionts = mix of gamma- and epsilon-Proteobacteria, E9 epibionts = epsilon-Proteobacteria) and in turn the relative contribution of carbon fixed via the reductive tricarboxylic acid (rTCA) and CBB cycles assimilated by Kiwa sp. Site differences in carbon fixation pathways were traced into higher trophic levels e.g. a stichasterid asteroid that predates on Kiwa sp. Sponges and anemones at the periphery of E2 assimilated a proportion of photosynthetic primary production but this was not observed in vent fauna from E9. The differences in δ13C and δ34S values of vent fauna at E2 and E9 sites suggest possible differences in the relative contribution of photosynthetic primary production and chemoautotrophic carbon fixation via CBB and rTCA cycles to the hydrothermal vent food webs.

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First Name: 
William D K
Last Name: 
Reid
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00441912225607
Affiliation: 
School of Marine Science & Technology, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
First Name: 
Christopher J
Last Name: 
Sweeting
Affiliation: 
School of Marine Science & Technology, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
First Name: 
Ben D
Last Name: 
Wigham
Affiliation: 
School of Marine Science & Technology, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
First Name: 
Katrin
Last Name: 
Zwirglmaier
Affiliation: 
Technische Universitaet Muenchen, Wissenschaftszentrum Weihenstephan, Limnologische Station Iffeldorf, Hofmark 1-3, 82393 Iffeldorf
First Name: 
Jeff A
Last Name: 
Hawkes
Affiliation: 
Ocean & Earth Science, University of Southampton, National Oceanography Centre Southampton, Southampton, SO14 3ZH, UK
First Name: 
Nicholas V C
Last Name: 
Polunin
Affiliation: 
School of Marine Science & Technology, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
Choose keywords that are most applicable to your abstract. (Three maximum.): 
Trophic relations (including symbiosis)
Ecological Interactions
Abstract ID: 
CBE5-129