Spatiotemporal changes in surface sediment characteristics and benthic macrofauna composition off the Rhône River in relation to its hydrological regime

• Published in: Estuarine, coastal and shelf science Vol. 151; pp. 196 - 209
• Main Authors: Bonifácio, Paulo, Bourgeois, Solveig, Labrune, Céline, Amouroux, Jean Michel, Escoubeyrou, Karine, Buscail, Roselyne, Romero-Ramirez, Alicia, Lantoine, François, Vétion, Gilles, Bichon, Sabrina, Desmalades, Martin, Rivière, Béatrice, Deflandre, Bruno, Grémare, Antoine
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 05-12-2014; Elsevier
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Brackish; Brackish water ecosystems; Deltas; Drying; Earth Sciences; Floods; Freshwater; Fundamental and applied biological sciences. Psychology; Hydrology; Mediterranean Sea; particulate organic matter; Rhône River; Rivers; Sciences of the Universe; Sea water ecosystems; Sediments; Stations; Synecology; Temporal logic; temporal variations; zoobenthos; France; Saone-Rhone Basin; Mediterranean Sea; Europe; European rivers; MED, France, Provence-Cote d'Azur, Rhone R; floods; particulate organic matter; temporal variations; Mediterranean Sea; Rhône River; zoobenthos; Brackish water environment; Composition; Fauna; Zoobenthos; Particulate organic matter; Sediments; River basins; Time variation; Marine environment; Flood; Macrofauna; Benthic zone
• ISSN: 0272-7714; 1096-0015
• DOI: 10.1016/j.ecss.2014.10.011

The consequences of changes in the water flow of the Rhône River on surface sediment characteristics and benthic macrofauna composition were assessed within 3 distinct areas: (1) the delta front, (2) the prodelta, and (3) the distal zone. Five stations were sampled during or closely after: (1) an oceanic flood (April 2007), (2) a generalized flood (May 2008), (3) a Cevenol flood (December 2008), and (4) a dry period (July 2011). Measurements of sediment characteristics included granulometry (D0.5), bulk descriptors of sedimentary organics (OC, TN and THAA), descriptors of labile components of sedimentary organics (chloropigments, EHAA), and both descriptors of origin (Chl-b/Chl-a, C/N) and lability (Chl-a/(Chl-a+Phaeo-a), EHAA/THAA) of sedimentary organics. Sediment Profile Images were collected during April 2007, May 2008 and July 2011. Temporal changes in both sedimentary organics and benthic macrofauna were more important in the delta front and the prodelta than in the distal zone. Bulk characteristics of sedimentary organics presented decreasing inshore/offshore gradients during both April 2007 and July 2011 but not during May and December 2008. There were significant temporal changes in EHAA/THAA at all stations. Changes in benthic macrofauna composition differed between: (1) the delta front and the prodelta, and (2) the distal zone. In the former area, the dry period was associated with establishing a mature community characterized by high abundances and species richness. The best description of spatiotemporal changes in benthic macrofauna composition by surface sediment characteristics was obtained using D0.5, Chl-b/Chl-a, Chl-a/(Chl-a+Phaeo-a) and EHAA, which supports the role of the quality of sedimentary organics in controlling benthic macrofauna composition.
•Four contrasted situations in terms of Rhône River flows are studied.•Important spatiotemporal changes in surface sediment characteristics are observed.•Changes in benthic macrofauna composition reflect directly the inputs of sediments.•Temporal changes in sediment characteristics and in benthic macrofauna are linked.