Fear over Arcachon Bay

A threatening seaweed

Maria and Jean-Michel Douet are standing on hot coals. In their cabin of the Cap-Ferret, the two young oyster famers are waiting for a fateful text message. « Tests performed in Arguin and in the Bassin came out positive for oyster and mussels. Everything is shut down. Courage and see you soon. » In oyster farming language this means disaster. Especially since the same scenario has been happening over and over again for the past five years and threatens 380 farms working on the 780 hectares of oyster beds yielding between 8,000 and 10,000 tons of oysters a year.

Jean-Michel and Maria Douet, young oyster farmers, are under pressure of the sanitary authorities © Philippe Henry / OCEAN71 Magazine

Dinophysis, a natural but toxic micro-alga seems to be the culprit. It releases a toxin which causes diarrhea in oyster eaters who ingest it. Oysters are water filters. They absorb and reject liters of sea water on a daily basis. They are thus the first to be contaminated. Even if this unwelcomed alga has never caused a single fatality, the European Union imposes the famous mouse biological test (see in chapter 2) in the name of the holly precaution principle, making oyster farmers hostages of the death, or survival of the little white mice…

The micro-seaweed dinophysis. If ingested the result in most cases is diarrhea. But this is enough for the French health authorities to forbid the sell of oysters © Philippe Henry / OCEAN71 Magazine

After years of research, the teams of the Institut français de recherche pour l’exploitation de la mer (Ifremer – French Institute for Exploitation of the Sea) have established a list of elements coinciding with the apparition of the dinophysis. « Spring unfortunately combines a number of events which seem to perfectly suit the alga, explains Roger Kantin, head of the Arcachon Ifremer station. Increasing daylight period, rise in water temperature (from 17°C) combined with fresh water influx carrying nitrates and phosphates from rivers which flow into the Bassin d’Arcachon. » As for the last two elements, they seem to be clearly resulting from human activity.

Other files

  • Hell in the Chagos heaven

    Ecology, Economy, Geopolitics5 chapters

    The Chagos archipelago. A name that sounds like the perfect place to spend the holidays. However, aside from the US army and a couple of privileged ones, the area is strictly forbidden. In one of the world well kept secrets, Great-Britain and the United States have conducted a large scale state scandal : 40 years ago, a small population of 2’000 people were simply forced to exile from their native land. To this day, they are still forbidden to return.

  • Nigeria’s dangerous oil

    Geopolitics1 chapter

    Pierre* is an officer in the French merchant navy as there are thousands across the world. Yet, after a six-month mission to Nigeria, he returns with a first hand account. The experience of a man who has worked in the very closed oil world in the Gulf of Guinea. Pierre was not laid off. He has simply decided to stop working in this little known hell.

  • High seas entrapment

    Sailing6 chapters

    On February 8, 2010, Alinghi and BMW-Oracle disputed the 33rd edition of the legendary America’s Cup. Behind the two sea monsters, two businessmen have been waging a merciless war for two years. An investigation on the four corners of the world, at sea and on land.