Spatiotemporal dynamics of surface sediment characteristics and benthic macrofauna compositions in a temperate high-energy River-dominated Ocean Margin

The benthic compartment of River-dominated Ocean Margins (RiOMar) is largely affected by sedimentary processes, as well natural and anthropogenic disturbances. Recent studies have confirmed the major importance riverine inputs local hydrodynamics in spatial structuration low- high-energy temperate RiOMar, respectively. Differences nature these structuring factors could also affect temporal dynamics two types systems. present study aiming at: (1) quantifying spatiotemporal changes surface sediment macrofauna within West Gironde Mud Patch (WGMP; system) over both short (2016–2018) longer (2010/2016–2018) time scales, (2) identifying main environmental explaining those changes, (3) achieving a comparison with Rhône River Prodelta (RRP; low-energy view further characterizing functioning components RiOMar. Surface characteristics (grain size, quantitative qualitative descriptors particulate organic matter) compositions were assessed based on 4 seasonal sampling 5 stations located along depth gradient WGMP. Results highlighted existence patterns for macrofauna, which are better explained hydrodynamics. Most variables presented changes. Benthic showed pluri-annual attributed to cicatrization process following disturbance caused 2013–2014 series severe winter storms, suggests role 2010/2016–2018 WGMP compositions. RRP discrepancies between systems processes (i.e., versus river hydrological regime) compositions, supports current RiOMar typologies.