The main objectives of the present project ZODARSED are(1) to better understand the physical causes of Zostera spp. decline, (2) to unravel physicalconsequences and quantify possible synergetic effects interplaying between the seagrasses and the sediment dynamics in the bay, and (3) to investigate past and future ecosystem responses to changes of environmental conditions.Keywords : Ecosystem engineers, Feedbacks, Statistical growth model, Coupled Numerical Modeling, Arcachon Bay, Environmental Forcing, Global Change, Zostera noltei

This internship takes place at Oceanographic Institute of University of Sao Paulo. It deals with the numerical modeling of transport of suspended particulate material in the estuarine-lagoon complex of Cananéia-Iguape that presents an important anthropogenic intervention, an artificial channel, named Valo Grande. The study aims to understand the hydrodynamic of the system and to know the behavior of suspended particulate material in surface and bottom water. Some in situ sampling contributed to complete data. This report contains a description of the step used to compile Delft3D. Initially, results show how important is the tide in the circulation of water in the total region and also show the influence of the fresh water dominance in the northern part of the system in function of the outflow of Ribeira River across the Valo Grande. This work should be continued with introduction of obtained suspended materiel data to observe discharge simulation

In order to follow the evolution of Berre lagoon’s ecology, EDF asks iXSurvey to measure the physico-chemical parameters on several points of the lagoon.During the internship, I took part in the improvement of the informatic tools to control and valid temporal series of oxygen and chlorophyll. The data were logged by YSI sensors located on the surface and at the bottom in three stations in Berre Lagoon.The study of factors acting on the biogeochemistry of the pond and thus on the variability of the measurement allows to group the data in classes. For example, data such as recording dates or wind parameters allow the creation of data groups using Visual Basic. Matlab is used in order to synchronize data. Then, a statistical analysis on the groups allows one to observe a reduction of the variability.

To follow water movement within the ocean, scientists use plotters as temperature or salinity. At Roscoff Biological Station, plotter’s evolution is measured every two weeks by chemical analysis of seawater samplings (national SOMLIT project, low frequency) and by using sensors (Aaderaa, Sea Bird) in high frequency on various platforms (Astan buoy, FerryBox, Minilab). These sensors require calibrations. A calibration report contains coefficients used to convert the sensor voltage measurements in a corresponding unit value.Istudied the various steps required to create a file grouping these coefficients in a structure easy to read by a program to bring corrections on measures made by a sensor between two calibrations.

Different consequences of tidal energy extraction were observed as a free surface drop, a reduction of water velocity due to energy losses or an acceleration of water in order to solve the equations of continuity.