Benthic impact assessment of a dredge sediment disposal in a dynamic resilient environment.

The eastern part of the Bay of Seine (English Channel) is highly impacted by harbour activities and the dumping of dredged sediment by the port authorities of Le Havre (GPMH) and Rouen (GPMR). Sediment dredged by the GPMH (2-2.5 millions of m per year) has been disposed at the subtidal Octeville site since 1947.

Effect of emersion/immersion cycles on the elemental and isotopic compositions of the organic matter from surface sediments of an intertidal mud bank (French Guiana): a preliminary study.

Rationale: In various marine environments, the combination of elemental ratios and stable isotopic compositions is usually used to trace the sources of organic matter (OM) in sediments. However, in intertidal areas, the sediments might be temporarily exposed to air during a more or less prolonged duration and the impact of this exposure on the latter parameter is unknown.

Methods: The spatial variations of atomic Total Organic Carbon (TOC) and Total Nitrogen (TN) ratios, and δ(13)C and δ(15)N values, were measured on surface sediments of French Guiana, at the beginning and the end of five consecutive days of emersion during equinoctial tides, as well as at the beginning of a new emersion phase after returning to a normal tidal cycle.