MEPS 501:11-23 (2014)  -  DOI:

Benthic metabolism in shallow coastal ecosystems of the Banc d’Arguin, Mauritania

Jacques Clavier1,*, Laurent Chauvaud1, Erwan Amice1, Pascal Lazure2, Matthijs van der Geest3, Pierre Labrosse4, Ahmed Diagne4, Antoine Carlier5, Sylvain Chauvaud6

1IUEM, Laboratoire des Sciences de l’Environnement Marin, UMR CNRS 6539, Institut Universitaire Européen de la Mer, Technopôle Brest-Iroise, Place Nicolas Copernic, 29280 Plouzané, France
2IFREMER, Laboratoire de Physique Hydrodynamique et Sédimentaire, Centre de Bretagne, ZI de la pointe du Diable, CS 10070, 29280 Plouzané, France
3NIOZ, Royal Netherlands Institute for Sea Research, Department of Marine Ecology, PO Box 59, 1790 AB, Den Burg, Texel, The Netherlands
4Institut Mauretanien de Recherches Océanographiques et des Pêches (IMROP), BP 22, Nouadhibou, Mauritania
5IFREMER, Laboratoire d’Écologie Benthique, Centre de Bretagne, ZI de la pointe du Diable, CS 10070, 29280 Plouzané, France
6Télédétection et Biologie Marine (TBM), 6 rue Castel, 56400 Auray, France
*Corresponding author:

ABSTRACT: Benthic primary production and respiration were investigated at 4 sites representative of the major coastal communities bordering the Sahara Desert in the Banc d’Arguin, Mauritania, Western Africa. These sites correspond to intertidal Zostera noltii beds (270 km2), intertidal bare sediments (88 km2), subtidal Cymodocea nodosa beds (374 km2), and subtidal bare sediments (311 km2). At each site, production–irradiance relationships were established in situ in November 2008 and January 2010, and used to calculate daily carbon fluxes for these communities. In intertidal areas, compared to emersion, the gross maximal photosynthetic rates for Z. noltii bed and bare sediment communities were on average 8- and 7-fold higher during immersion, respectively; community respiration rates were 3- and 18-fold higher during immersion, respectively. The Z. noltii bed was autotrophic during the 2 study periods, with a mean (±95% probability limit) daily net community production of 71.3 ± 58.6 mmol C m-2 d-1. Conversely, net community production was always negative in intertidal regions and subtidal bare sediments (average -7.3 ± 46.7 mmol C m-2 d-1 and -47.0 ± 38.9 mmol C m-2 d-1, respectively); the C. nodosa bed was negative in November (-96.2 ± 85.1 mmol C m-2 d-1) and positive in January (33.4 ± 82.6 mmol C m-2 d-1). Community respiration was highest in subtidal communities, indicating active mineralization of organic matter and demonstrating that Z. noltii beds are likely to increase the biological richness of the Banc d’Arguin by exporting energy. Our results confirm the ecological importance of seagrass beds in the net coastal carbon fluxes and justify their protection.

KEY WORDS: Seagrass · Carbon metabolism · Intertidal · Subtidal · Respiration · Primary production · Western Africa

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Cite this article as: Clavier J, Chauvaud L, Amice E, Lazure P and others (2014) Benthic metabolism in shallow coastal ecosystems of the Banc d’Arguin, Mauritania. Mar Ecol Prog Ser 501:11-23.

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