They begin knowing about it more about the impact of pollutions on aquatic life. After eight years of inquiry into the ground and in laboratory, an American team concludes in the guilt of the men in the curiosity of a fish of the estuary of San Fransisco (California). She publishes her jobs in the edition of November 24th of the Annals of the American academy of sciences.

The abundance of the striped bar, Morone saxatilis, roughly fell in are the seventies. In spite of measures of protection, its population continued declining. Until now, several hypotheses were envisaged: the excessive pumping of the water of the river of Sacramento for irrigation, lack of food, climatic warming and pollution. At the same time, studies had shown in laboratory the influence of some pollutants on the development of the larvas of the striped bar. This time, the researchers are definite. They are many chloric molecules and bromées who are the culprits.

Samples conduit in situ notably show high contents of PCB and PBDE (1) in eggs of striped bar. Products which have the capacity to pile up in grease. Result of this pollution, the larvas develop more slowly than normal. Their cerebral system also.

If eggs are contaminated, it is although the females are him. Impregnated with PCB and PBDE, 21 specimen studied therefore laid of eggs with high content of pollutants known to corrupt development. PCB and PBDE, but also applied pesticides or which are not any more used for a long time, as DDT. Sign that the dispersion of phytosanitary products pollutes environment during decades.

While to make. For PCB, there is alas a little to be, otherwise to wait. As their usage strongly diminished — it is forbidden it is a relic which will pollute the sludge, the fish which draw their food, and the predators who are at the end of food chain. On the other hand, the role of PBDE is more worrying. Because these products are still widely used as retarding of flame in plastics, fabrics for furnishing, painting, moquettes, etc. The authors of study remind that they find that this family of molecules in the milk of the women who nurse, in the region of San Fransisco, in contents hundred higher times than elsewhere. Alone a restriction or even a ban of their usage could improve situation. It is found to in the fish of the Arctic, good far from the zones of pollution.

In France, a strong pollution in PCB raised in the fish of the Rhône in 2007 had led authorities to forbid their peach and their consumption. A pollution which also touches some Alpine lakes.

(1) PCB: polychloro-biphenyl. PBDE: polybromo diphenyl aether.

Picture: A larva of striped bar, a day after hatching © David Ostrach