EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Vertical distribution and aerobic degradation at the sediment-water interface in two urbans estuaries in Normandy, France

Amonda El Houssainy1,2, Isabelle Poirier1,2, Martine Bertrand1,2, Laure Verdier3, and Florian Cesbron1,2
Amonda El Houssainy et al.
  • 1Conservatoire National des Arts et Métiers, Institut National des Sciences et Techniques de la Mer, EPN8, Boulevard Collignon, Tourlaville, 50110, Cherbourg en Cotentin, France (;; martine.bertrand@lec
  • 2LUSAC - Laboratoire Universitaire des Sciences Appliquées de Cherbourg, 60 rue Max-Pol Fouchet, CS 20082, 50130 Cherbourg-en-Cotentin, France
  • 3Cité de la mer, gare Maritime Transmanche, 50100 Cherbourg en Cotentin, France (

In the current context of climate change, the coastal area is exposed to an increasing pressure from hydrodynamic agents such as tide, flood and storm (Parry et al., 2007) and to enormous anthropogenic activities due to urbanization and industrialization of the coastline, which weakens the coastal ecosystem. In France, the Manche department presents more than a half of the Normandy coastline (330 km) and a great diversity of its shores. It is a key player in the preservation of the coastal environment. Among its conservation areas, two estuaries in Saint-Vaast-La-Hougue interested us: the Saire Estuary and Cul-de-Loup Bay, which both subjects to the impact of human activities (agriculture, shellfish farming, tourism, modification of the coastline, etc.). In order to quantify the chemical and biological exchanges in the mudflat of these two sites, we performed dissolved oxygen profiles in the sediment using a benthic microprofiler system (Unisense®). Moreover, sediment cores were collected and sliced under inert atmosphere, in order to measure diagenetic tracers (NH4+, PO43-, Fe2+ and ΣHS-) and trace metals levels, and to identify bacterial communities. The results of sediment cores and oxygen microprofiles taken from each of the mudflat indicate a greater dynamic degradation of organic matter in the superficial sediments of Saire estuary and in deep sediment of Cul-de-Loup Bay. The benthic microprofiler results show that oxygen penetration depth is around 1 mm and 1.4 mm respectively in Saire estuary (n=3) and Cul-de-Loup bay (n=5). This difference is marked by (i) an intense reduction of Fe (oxy)hydroxides at 4 cm of sediment depth in the Saire estuary, (ii) the appearance of ΣHS- from ~ 12 cm of sediment depth against 5 cm of sediment depth in the Cul-de-Loup Bay and (iii) a slight Fe(oxy)hydroxide zone at 3 cm of sediment depth. Metagenomics analysis confirm major differences between the two study sites.

How to cite: El Houssainy, A., Poirier, I., Bertrand, M., Verdier, L., and Cesbron, F.: Vertical distribution and aerobic degradation at the sediment-water interface in two urbans estuaries in Normandy, France, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12143,, 2022.