TY - JOUR TI - Multiple effects of a Gracilaria vermiculophylla invasion on estuarine mudflat functioning and diversity AU - Davoult, D. AU - Surget, G. AU - Stiger-Pouvreau, V. AU - Noisette, F. AU - Riera, P. AU - Stagnol, D. AU - Androuin, T. AU - Poupart, N. T2 - Marine Environmental Research AB - The invasive Japanese seaweed Gracilaria vermiculophylla has become established over the past several years in numerous European estuaries, from Portugal to Norway. In the Faou estuary (48.295 degrees N-4.179 degrees W, Brittany, France), it forms a dense population at the mud's surface. The effects of G. vermiculophylla on metabolism, diversity, and the food web were studied. Community gross primary production (GPP) and respiration (CR) during emersion, chlorophyll-a content, macrofaunal and meiofaunal diversity and abundance, and stable isotopes (delta C-13 and delta N-15) of representative macrofaunal species and main food sources were measured at low tide in winter, spring, summer 2014, and winter 2015. Results show significant seasonal variation in GPP and CR. Moreover, GPP was significantly higher in areas where G. vermiculophylla was present than in the control area (bare mud). However, this high GPP appeared to be linked to the increase in biomass in primary producers, with their efficiency (primary productivity, i.e. assimilation number) remaining relatively stable compared with the control area. Significant variation in abundance of meiofauna and macrofauna was also detected and new epifaunal species were collected, mainly in Gracilaria-colonized areas. Isotopic food-web Bayesian mixing models strongly suggested that G. vermiculophylla plays a major role in the diet of some dominant species. Mechanisms interacting with the functioning and diversity of the mudflat are discussed. Finally, the invasive seaweed G. vermiculophylla affected the mudflat ecosystem in three ways: as a new primary producer (increase in metabolism), as a habitat-forming species (changes in diversity and abundance of macrofauna and meiofauna), and as a new abundant food source, likely through the detrital pathway. DA - 2017/10// PY - 2017 DO - 10.1016/j.marenvres.2017.09.020 DP - Web of Science VL - 131 SP - 227 EP - 235 J2 - Mar. Environ. Res. LA - English SN - 0141-1136 UR - http://www.sciencedirect.com/science/article/pii/S0141113617304129 KW - ACL KW - Engineer species KW - Food web KW - INVASIVES_ANR-12-SEAS-0002 KW - Invasive KW - Macrofauna diversity KW - Meiofauna diversity KW - Metabolism KW - Non-indigenous species KW - Red alga KW - UBO KW - bay KW - biological invasions KW - crassostrea-gigas KW - crepidula-fornicata KW - delta-n-15 KW - ecosystem engineers KW - france KW - impacts KW - macroalgae KW - panorama KW - seaweed ER -