OMEX

Quantification of fluxes across the ocean margins is a fundamental requirement for the evaluation of the carbon budget and exchange of nutrients and associated trace elements between the continents, the coastal zone, and the open ocean.
Ocean Margin Exchange (OMEX) was designed to study the exchanges and processes occurring at the European continent/ocean margins in the North Atlantic. OMEX is a process-oriented project composed of five subprojects:
Physics, Biological Processes, Biogeochemical Cycles, Benthic Processes - including Geology, Geochemistry and Biology-, and finally Carbon Cycling & Biogases.

The objectives of OMEX may be formulated in terms of the following key questions:

1) What are the principal processes controlling fluxes of  water and particles in geomorphologically contrasting  slopes or shelf-edge systems?

2) Which part of the shelf primary production is sustained by oceanic nutrient fluxes versus river and atmospheric inputs?

3) Is shelf production exported to the open ocean and are shelf slopes depo-centres for the missing carbon?

4) What are the consequences of biologic discontinuities and of benthic-pelagic uncoupling at the shelf edge on the carbon fluxes?

5) Is the diversity in the benthic community structure and production controlled by the balance between horizontal and vertical fluxes?

6) How does the ocean margin exchange affect the behaviour of trace elements? How do the scavenging processes in shelf edge systems control the reactivity and residence time of trace metals and radionuclides?

7) What are the characteristics and types of biogases  produced on the shelf, exchanged with the atmosphere, or exported to the open ocean?

8) What is the sensibility of the processes mentioned in the above questions in response to global climatic change and sea-level rise?

The European coastal and continental margin setting provides a unique opportunity for investigating a wide diversity of ocean margin environments. During the first phase of the OMEX project, the Goban Spur area in the Celtic Sea (characterized by a broad continental shelf where the circulation is dominated by internal tides and waves) was chosen as the principal study site. The Iberian margin (characterized by a very narrow continental shelf, a very steep continental slope, and a limited river water input where upwelling of deep ocean waters onto the shelf is coupled with offshore transport of surface waters following northerly winds) has been selected as a secondary site for OMEX.