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Marine Ecology Progress Series

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MEPS 516:127-138 (2014)  -  DOI:

Trophic role of large benthic sulfur bacteria in mangrove sediment

Pierre-Yves Pascal1,*, Stanislas Dubois2, Henricus T. S. Boschker3, Olivier Gros1

1Département de Biologie, Université des Antilles et de la Guyane, UMR 7138 UPMC-CNRS-MNHN-IRD, Equipe ‘biologie de la mangrove’, UFR des Sciences Exactes et Naturelles, BP 592, 97159 Pointe-à-Pitre, Guadeloupe, France
2IFREMER, DYNECO Laboratoire d’Ecologie Benthique,29280 Plouzané, France
3Royal Netherlands Institute of Sea Research (NIOZ), PO Box 140, 4400 AC Yerseke, The Netherlands
*Corresponding author:

ABSTRACT: Large filamentous sulfur-oxidizing bacteria belonging to the Beggiatoacae family can cover large portions of shallow marine sediments surrounding mangroves in Guadeloupe (French West Indies). In order to assess the importance of Beggiatoa mats as an infaunal food source, observations were conducted of the area within mats and at increasing distances from mats. We used natural isotopic compositions and a 13C enrichment study. Both revealed an ingestion of bacterial mats by associated meiofauna, dominated by rotifers and to a smaller extent by small polychaetes and nematodes. Compared to adjacent sites, sediment covered by bacterial mats presented a higher abundance of diatoms, whereas the total biomass of bacteria did not vary. This constant bacterial abundance suggests that the proportion of organic matter represented by sulfur bacteria is limited compared to the fraction of total bacteria. There was no significant difference in infaunal abundance in mats, suggesting that the availability of this chemosynthetic food resource had a limited local effect. Grazers presented a δ13C value increasing with distance from the mat. However, isotopic composition of phospholipid-derived fatty acids specific for diatoms and bacteria revealed that this change is related to modifications of δ13C dietary components rather than to changes in diet composition. These complementary methods revealed that the occurrence of sulfur-oxidizing bacterial mats does not necessarily affect grazer abundance and importance of bacteria in their diet. Despite its wide occurrence, Beggiatoa mats would consequently have a minor influence on the structure of the mangrove food web.

KEY WORDS: Beggiatoa · Mangrove · Benthic food web · Sulfur bacteria · Meiofauna · Nematode · Rotifers · Stable isotope

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Cite this article as: Pascal PY, Dubois S, Boschker HTS, Gros O (2014) Trophic role of large benthic sulfur bacteria in mangrove sediment. Mar Ecol Prog Ser 516:127-138.

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