Data/hora: 03/06/2024 04:30:00

Provedor de dados: | 5
País: | France
Título: | Devenir des bactéries dans les réseaux trophiques des vasières intertidales : le cas de brouage (Baie de Marennes-Oléron)
Autores: | Pascal, Pierre-yves.
Data: | 2008-01-24
Ano: | 2008
Palavras-chave: | Stable isotope; Hydrobia ulvae; Foraminifera; Copepod; Nematode; Bacteria; Mudflat; Trophic foodweb; Isotope stable; Hydrobia ulvae; Foraminifère; Copépode; Nématode; Bactérie; Vasière; Réseau trophique.
Resumo: | Bacteria are highly abundant and productive in intertidal mudflat sediments. By analogy  with pelagic system, it has been suggested that bacteria play an important role in benthic food  web. Due to technical difficulties, numbers of studies dealing with benthic bacterivory are not  numerous and give conflicting results. A method using community of 15N enriched bacteria as  tracer was developed in order to measure grazing of meiofauna and macrofauna. Since enriched  bacteria present characteristics of size, activity and diversity close to natural ones, bias due to  selective bacterial ingestion by grazers are limited. Due to tidal cycles, intertidal mudflat  constitutes highly variable environment at short time scale. Since those variations may influence  the feeding behavior of grazers, grazing experiments were performed in order to evaluate effects  of abiotic (temperature, salinity and luminosity) and biotic (bacterial and algal abundances)  factors on rates of bacterial uptake. Studied grazers were the mudsnail Hydrobia ulvae, the  foraminifera Ammonia tepida and a nematode community from Brouage mudflat (Marennes-  Oléron Bay). Except A. tepida, grazers were poorly affected by abiotic factors. This result suggests  that grazers are adapted to feed in the highly variable environment constituted by the  air/sediment interface where algal biofilm appears during diurnal ebb. Algae were ingested at a  higher rate than bacteria suggesting a lower importance of bacteria in grazer diets. In order to  measure annual variations of bacterial ingestion, regular grazing experiments were performed in  situ in Brouage mudflat. Nematode community and A. tepida presented a bacterivory negatively correlated with bacterial abundance suggesting that bacteria represent an alternative resource  that is grazed when algal abundances are low. The grazing of studied grazer never represented  more than 6% of bacterial production. As a result, grazing constitutes a limited fate of benthic  bacteria in the Brouage mudflat.
Tipo: | Text
Idioma: | Francês
Identificador: | http://archimer.ifremer.fr/doc/2008/these-4778.pdf
Editor: | Université de La Rochelle
Relação: | http://archimer.ifremer.fr/doc/00000/4778/
Formato: | application/pdf