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Marine Ecology Progress Series

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MEPS 529:91-105 (2015)  -  DOI: https://doi.org/10.3354/meps11297

Role of pockmarks in diversity and species assemblages of coastal macrobenthic communities

Stanislas F. Dubois1,*, François Dérian1, Xavier Caisey1, Carinne Rigolet1,2, Jean-Claude Caprais3, Eric Thiébaut2,4

1Laboratoire Ecologie Benthique, Dynamiques de l’Environnement Côtier (DYNECO), Institut Francais de Recherche pour l’Exploitation de la Mer (Ifremer), Technopole Brest-Iroise, BP 70, 29280 Plouzané, France
2Sorbonne Universités, Université Pierre et Marie Curie/Université Paris 06, Unité Mixte de Recherche 7144, Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, 29680 Roscoff, France
3Département Etude des Ecosystèmes Profonds (DEEP), Institut Francais de Recherche pour l’Exploitation de la Mer (Ifremer), Technopole Brest-Iroise, BP 70, 29280 Plouzané, France
4Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche 7144, Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, Place Georges Teissier, 29680 Roscoff, France
*Corresponding author:

ABSTRACT: We used existing bathymetric data to study the macrofauna of a geophysical pockmark field restricted to a benthic habitat engineered by the tubiculous amphipod Haploops nirae in South Brittany (France). Stations inside and outside pockmarks of different morphometric characteristics (location, size, depression depth) were sampled for macrofauna and environmental parameters (sediment characteristics, organic matter, chl a, hydrogen sulfide and methane concentrations). Diversity indices showed higher species richness inside pockmarks, especially for species with medium to high abundances. Most sediment cores showed low methane but high hydrogen sulfide concentrations. We hypothesised that after eruption, the remaining residual methane from pockmark sediments is oxidised by seawater sulfate and accounts for the high sulfide concentrations found at increasing depth in our samples and the low methane concentrations. We found no relationship between sediment profiles and morphometric features of the pockmarks. Macrofauna assemblages inside vs. outside pockmarks appeared to be different. Pockmarks appear to increase connectivity among habitats and heterogeneity within habitats, thereby creating local hotspots that allow the settlement of species that cannot otherwise develop in Haploops tube mats. Multivariate analyses distinguished 4 groups of pockmarks and control stations. We assumed that deeper pockmarks were created more recently than shallow pockmarks and that each pockmark is at a different stage of evolution, hence explaining the large variability in the characteristics of pockmark groups. This explains why previous investigations have found contradictory results when comparing macrofauna species diversity and composition between areas inside and outside pockmarks. Finally, we propose and discuss a successional stage model for pockmarks.


KEY WORDS: Benthic habitat · Biodiversity · Succession · Amphipod · Haploops · South Brittany · Sulfide · Methane · Environmental factors


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Cite this article as: Dubois SF, Dérian F, Caisey X, Rigolet C, Caprais JC, Thiébaut E (2015) Role of pockmarks in diversity and species assemblages of coastal macrobenthic communities. Mar Ecol Prog Ser 529:91-105. https://doi.org/10.3354/meps11297

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