MEPS 466:93-119 (2012)  -  doi:10.3354/meps09896

Seep communities from two mud volcanoes in the deep eastern Mediterranean Sea: faunal composition, spatial patterns and environmental control

Bénédicte Ritt1,2,*, Daniel Desbruyères1, Jean-Claude Caprais1, Olivier Gauthier3, Livio Ruffine1, Roselyne Buscail4, Karine Olu-Le Roy1, Jozée Sarrazin

1Ifremer Brest, REM/EEP & REM/GM, Institut Carnot Ifremer-EDROME, BP 70, 29280 Plouzané, France
2Biology Department, Temple University, 1900 North 12th Street, Philadelphia, Pennsylvania 19122, USA
3IUEM, UBO, Technopôle Brest-Iroise, Place Nicolas Copernic, 29280 Plouzané, France
4CEFREM, CNRS, UMR 5110, Université de Perpignan, 52, avenue Paul Alduy, 66860 Perpignan, France

ABSTRACT: The Mediterranean Sea constitutes a unique environment to study cold-seep ecosystems due to the presence of different geodynamic settings, from an active margin along the Mediterranean Ridge (MR) to a passive margin in the Nile Deep-Sea Fan (NDSF). We attempted to identify the structure of benthic communities associated with the Napoli and Amsterdam mud volcanoes (MVs) located on the MR and to establish the links between faunal distribution and environmental conditions at different spatial scales. Comparison between the 2 MVs revealed that the faunal distribution seemed to be mainly controlled by the characteristics of the microhabitats. On both geological structures, the variability between the different microhabitats was higher than the variability observed between replicates of the same microhabitat, and the distribution of macrofauna was apparently linked to gradients in physico-chemical conditions. The peripheral sites from Napoli were generally more oxygenated and harboured lower species richness than the active sites. The reduced sediment microhabitat from Amsterdam presented the highest methane concentrations and was mainly colonised by symbiont-bearing vesicomyid bivalves and heterotrophic dorvilleid polychaetes. Overall, a higher taxonomic diversity was observed on Napoli. Substratum type was hypothesised to be the second factor influencing faunal distribution. The results of this study highlight the high heterogeneity of faunal communities associated with seep ecosystems within this region and the need to pursue investigations at various spatial and temporal scales.

KEY WORDS: Mediterranean Ridge · Cold seeps · Benthic fauna · Environmental conditions · Diversity indices · Microhabitats

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Cite this article as: Ritt B, Desbruyères D, Caprais JC, Gauthier O and others (2012) Seep communities from two mud volcanoes in the deep eastern Mediterranean Sea: faunal composition, spatial patterns and environmental control. Mar Ecol Prog Ser 466:93-119

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