Influence of oyster culture on biogeochemistry and bacterial community structure at the sediment–water interface

• Published in: FEMS microbiology ecology 2012-10, Vol.82 (1), p.102-117
• Main Authors: Azandégbé, Afi, Poly, Franck, Andrieux-Loyer, Françoise, Kérouel, Roger, Philippon, Xavier, Nicolas, Jean-Louis
• Format: Article
• Language: English
• Subjects: Ammonia; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Aquaculture; Bacteria; Bacteria - classification; Bacteria - growth & development; Bacteria - isolation & purification; bacterial structure; biogeochemical parameters; Biogeochemistry; Biological and medical sciences; Community structure; Crassostrea gigas; Denaturing Gradient Gel Electrophoresis; DNA, Bacterial - genetics; Ecology; Environmental factors; Environmental Sciences; Estuaries; fluxes; France; Fundamental and applied biological sciences. Psychology; General aspects; Geologic Sediments - chemistry; Geologic Sediments - microbiology; Hypoxia; Marine; Microbial ecology; Microbiology; Organic matter; Ostreidae - growth & development; Oysters; Phylogeny; Seasons; Seawater; Seawater - chemistry; Seawater - microbiology; sediment; Sediment-water interface; Sediments; Shellfish farming; Sulfides; Synecology; Temperature; Various environments (extraatmospheric space, air, water); Vibrio; Vibrio - growth & development; Vibrio - isolation & purification
• ISSN: 0168-6496; 1574-6941
• DOI: 10.1111/j.1574-6941.2012.01410.x

Abstract Bacterial community structure and some biogeochemical parameters were studied in the sediment of two Pacific oyster farming sites, Aber Benoît (AB) and Rivière d'Auray (RA) in Brittany (France), to examine the ecological impact of oysters and to evaluate the emission of sulfide and ammonia from sediment. At AB, the organic matter accumulated in the sediment beneath the oyster tables was rapidly mineralized, with strong fluxes of ammonia and sulfide that reached 1014 and 215 μmol m−2 h−1, respectively, in June 2007. At RA, the fluxes were about half as strong on average and better distributed through the year. The ammonia and sulfide concentrations in the overlying water never reached levels that would be toxic to oysters in either site, nor did hypoxia occur. Total culturable bacteria (TCB) varied greatly according to the temperature: from 1.6 × 104 to 9.4 × 107 cell g−1 sediment. Inversely, the bacterial community structure remained surprising stable through the seasons, marginally influenced by the presence of oysters and by temperature. Bacterial communities appeared to be characteristic of the sites, with only one common phylotype, Vibrio aestuarianus, a potential oyster pathogen. These data refine the hypothesis of seawater toxicity to oysters because of ammonia and sulfide fluxes and show that the measured environmental factors had only a weak influence on bacterial community structure.