FN Archimer Export Format PT J TI Impact of the oyster Crassostrea gigas on a microbial community in Atlantic coastal ponds near La Rochelle BT AF DUPUY, Christine PASTOUREAUD, Annie RYCKAERT, Mireille SAURIAU, Pierre-Guy MONTANIE, Hélène AS 1:;2:;3:;4:;5:; FF 1:;2:PDG-DEL-ST;3:PDG-DEL-LR;4:;5:; C1 Ctr Rech Ecol Marine & Aquaculture, UMR 10, IFREMER, CNRS, F-17137 Lhoumeau, France. Univ La Rochelle, Lab Biol & Environm Marine, F-17042 La Rochelle, France. C2 CTR RECH ECOL MARINE & AQUACULTURE, FRANCE UNIV LA ROCHELLE, FRANCE SI LA ROCHELLE SETE SE PDG-DRV-RA-CREMA PDG-DEL-ST PDG-DEL-LR IN WOS Ifremer jusqu'en 2018 copubli-univ-france IF 2.19 TC 16 UR https://archimer.ifremer.fr/doc/2000/publication-822.pdf LA English DT Article DE ;Trophic link;Bacteria;Protists;Microbial food web;Coastal pond;Food source;Oysters;Bivalve AB To assess the in situ impact of oysters Crassostrea gigas on planktonic protist and bacteria communities and the potential contribution of protozoa to their food resource intake, the abundance and the diversity of protists and bacteria were followed in 2 Atlantic coastal ponds, with and without oysters. The protist biomass in such ponds was high, with a maximum in spring of 982 mug C l(-1) and a minimum in winter of 179 pg C l(-1). Whatever the season, the presence of oysters (20 m(-2) corresponding to an average of 23 mg dry weight m(-2)) induced a significant decrease in >5 pm protist abundance. On the contrary, planktonic organisms <5 pm, such as Chlorophyta flagellates and bacteria, developed similarly in both ponds. It can be assumed that such depletion in micro-sized protists was especially related to the grazing activity of C. gigas, which efficiently retains >5 pm particles. In spring, oyster grazing triggered dramatic changes in the protist community by lowering the taxonomic diversity. In autumn and winter, the presence of oysters deeply influenced the taxonomic structure of the protist communities: > Fun protists could only develop in the control pond, whereas they were removed by filtration in the oyster pond; on the contrary, >5 Fun protists that were not retained were favoured in the oyster pond. The results showed that hetero/mixotrophic protists represent an important potential resource in coastal ponds: flagellates >5 pm were the main protist resource for C. gigas; ciliates represented the second resource, with a substantial contribution in autumn; diatoms and dinoflagellates, though efficiently removed, represented a weak carbon resource. Our study supports the hypothesis that oysters may access the strong bacterioplanktonic production through hetero/mixotrophic protists, which would thus allow the transfer of carbon from the microbial loop towards C. gigas. PY 2000 PD OCT SO Aquatic Microbial Ecology SN 0948-3055 PU Inter-Research VL 22 IS 3 UT 000165351700002 BP 227 EP 242 DI 10.3354/ame022227 ID 822 ER EF