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

Lookup NU author(s): Dr William Reid, Dr Benjamin Wigham, Professor Nick Polunin

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Abstract

The Mid-Atlantic Ridge (MAR) is a topographically complex feature in the North Atlantic Ocean with little exploration of benthic fauna except in association with hydrothermal venting, resulting in the biodiversity and ecosystem functioning of the MAR benthos away from these sites remaining largely unknown. Stable isotope analysis of carbon, nitrogen and sulphur were undertaken on fauna collected north and south of the Charlie-Gibbs Fracture Zone, in areas believed to be devoid of hydrothermal venting, to investigate the trophodynamics of the benthic assemblage. delta C-13 and delta S-34 values of the benthic and bentho-pelagic fauna indicated a dependence on photosynthetic primary production, with no influence from an unknown chemosynthetic source. A large trophic discrimination in delta C-13 between consumers and potential food sources (particulate organic matter and surficial sediments) suggested reworking of organic carbon before assimilation by benthic fauna. Interpretation of sediment delta N-15 values was difficult as these ranged between -0.74 and 23.14%, suggesting further work is required to understand nitrogen utilisation by benthic deposit feeders. Differences in trophic guilds (predators, predator-scavenger, surface deposit feeders, subsurface deposit feeders and suspension feeders) were evident for delta C-13 and delta N-15, with the main difference between the mobile predators-scavengers and the benthic deposit feeders. Dividing the assemblage based on trophic guilds into food chains dependent on phyto detritus (deposit and suspension feeders) and predation-scavenging (fishes and crustaceans) resulted in strong positive correlations between delta N-15 and delta C-13 at both stations. These reflected the 2 dominant trophic pathways organic matter passed through deposit feeders and predatory and scavenging deep-sea fishes and crustaceans.

Publication metadata

Author(s): Reid WDK, Wigham BD, McGill RAR, Polunin NVC

Publication type: Article

Publication status: Published

Journal: Marine Ecology Progress Series

Year: 2012

Volume: 463

Pages: 89-103

Print publication date: 30/08/2012

ISSN (print): 0171-8630

ISSN (electronic): 1616-1599

Publisher: Inter-Research

URL: http://dx.doi.org/10.3354/meps09863

DOI: 10.3354/meps09863

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