Espace presseThema

The Ocean's Surface as Seen from the Top Microscopic Layer

Micro-Organisms and Organic Matter at the Sea/Air Interface

Taking samples of the surface micro-layer using metal screens. The water is collected in extremely clean glass bottles.

Philippe Lebaron of the Laboratory of Biological Oceanography1, located on France's Mediterranean coast at the Banyuls Observatory, is project coordinator for AIRWIN2, a study of organisms living at the air/sea interface and their interactions with organic matter of both natural and human origins.

How did the idea of the AIRWIN project originate?
Philippe Lebaron: A seminar organised in Paris in 1999 by the International Commission for the Scientific Exploration of the Mediterranean (CIESM) included a workshop about the biofilm which is found at the surface of the ocean. This film constitutes a marine ecosystem by itself, and a surprising one; although environmental conditions are far from being favorable to life, the film is characterised by an intense biological activity and diversity of organisms. Deposits of airborne pollutants, organic matter rising from the water column, and high doses of solar radiation including ultraviolet make the ocean's biofilm a particular and important barrier between atmosphere and oceans but also a poorly understood biotope.
Along with other European scientists we wanted to further characterise this surface layer, and therefore we developed a collaboration involving research teams from the CNRS, the University Pierre-et-Marie-Curie (University of Paris VI), The Oceanographic Institute (NIOZ, Texel, The Netherlands), the University of Barcelona, the International Atomic Energy Agency (IAEA, Monaco) and the French skin care and cosmetics company Pierre-Fabre.  The goal of the project is to study the structure and role of the biological communities involved in transporting and transforming organic matter at the sea/air interface. Data were gathered at two sites: a relatively protected zone off Banyuls-sur-Mer and a site exposed to much more human activity off Barcelona.


© CNRS. Laboratoire d'océanographie biologique de Banyuls

Atmospheric particles are collected using specially designed sampling devices, containing a series of filters.

What has already been accomplished?
P. L. The first task was to establish efficient sampling methods. This represented quite a challenge since each sample needed to be several liters of water taken from a layer only a few hundred microns deep! The first field trials in the summer of 2001 were an opportunity to compare methods. Then in 2002, two sampling programmes took place, in Barcelona and Banyuls, each involving 15 persons during one week. Now in the laboratory we are working to identify microorganisms (especially bacteria, but also viruses and phytoplankton) as well as the various chemical components of the film. We are interested in the role each of these plays in decontamination or, inversely, in transferring pollutants into the marine food chain. We are also looking at the ways they adapt to live in an environment highly exposed to ultraviolet radiation. Some of these organisms likely have developed mechanisms to protect against oxidative stress and UV exposure which would be of interest to industrial firms like Pierre Fabre.

What program for the future?
P. L. In January 2003 the Pierre Fabre Laboratories hosted a workshop in Toulouse to close the second year of the AIRWIN project. Results were examined together with outside specialists, and the objectives for the third and final year of the project were defined with input from everyone. In July 2003 a sampling expedition was carried out in the Mediterranean on board the CNRS vessel Thétys.




Philippe Lebaron
Laboratoire d'océanographie
biologique de Banyuls

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