Protected Marine Areas at Risk from Dredging Muds

15 Nov 2010

Conferences, symposiums, chitchat and roundtables So far, Protected Marine Areas are large spaces in which everyone wants to protect what they hold most dearly, aka, their own interests, even when those are as murky as dredging muds. The road to bringing reason to the active minorities, who are often polluting the most, is still long.

La Rochelle is, in this regard, quite edifying. As part of the extension and deepening of the pleasure-boating port of Minimes – for the benefit of trimarans, catamarans and monohulls, 1 million m3 of radioactive sludge and other pollutants must be extracted from the access channel to the old port by October 2011, and these extractions will be scattered at sea around the Pertuis Charentais Natura 2000 site. This 456,000 hectare area is described as one of the most productive marine ecosystems within the French waters, and several endangered species such as sturgeon, shad, and porpoises reside there. It is also an important economic resource for the professional fishermen, who, thanks to diversified techniques, supply auction and regional markets. Oyster ponds on the islands of Ré and Marennes-Oléron are labeled as part of the Pertuis Charentais.

The impact study of the La Rochelle harbor extension was performed in 2005. It does not incorporate neither the lessons learned from Xynthia nor the claims that the introduction of two new sea walls in La Rochelle Bay will not change the increase of flooding risks in the event of strong ocean storms. The chemical and physicochemical analysis made before 2005 do not take into account the redistribution of contaminants in the Bay sediments after Xynthia. However, the study warns of the potential toxicity of the sludge created by the harbor extension process. The incoming flow would be about 40 tons of lead, 1 ton of Polycyclic Aromatic Hydrocarbons, 360 kg of cadmium and 120 kg of mercury. The nitrogen and phosphorus flows released into the sea would be respectively of 1,500 and 700 tons. The bacteriological quality is either bad or very bad, depending on the five samples taken and analyzed before 2005. Suspending the activity of the treatment plant in Port Neuf for several weeks after Xynthia has undoubtedly exacerbated the situation. These poisons will be released onto the Antioche site – between Ré and Oléron islands – which is far from being abyssal, for it is only 20-25 meters deep. At Robin des Bois’ request, additional radiological analyses were conducted between 2009 and 2010. The average thorium level in marine sediments on the French coast is 8 mg / kg. Three sediment cores in the area to be dredged had levels at or above 40 mg / kg, in inheritance of the Rhodia factory, formerly known as the Rhône Poulenc. No studies on the radiological impact on marine biodiversity have been performed.

In conclusion, dumping dredging sludge in the Pertuis Charentais Natura 2000 site does not take into account the sanitary protection of marine biodiversity and fishing resources, nor does it with the shellfish health and public safety. It mocks the plan to fight green algae and sacrifices the ecological and economic balance of a vast mosaic of ecosystems in the sole interest of the nautical sector.

Robin des Bois believes this textbook case should be subject to new choices guided by the commitments of the Grenelle de la Mer and the teachings of Xynthia.




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