ACCUMULATION OF DEBRIS ON THE DEEP-SEA FLOOR OFF THE FRENCH MEDITERRANEAN COAST

The distribution and abundance of large marine debris were investigate d on the continental slope and bathyal plain of the northwestern Medit erranean Sea during 3 oceanographic cruises undertaken in June 1994, J uly 1995 and April 1996. Different types of debris were enumerated, pa rticularly pieces of plastic, plastic and glass bottles, metallic obje cts, glass and diverse materials including fishing gear. The results s howed considerable geographical variation, with concentrations ranging from 0 to 78 pieces of debris ha(-1). In most stations sampled, plast ic bags accounted for a very high percentage (more than 70%) of total debris. In the Gulf of Lions, only small amounts of debris were collec ted on the continental shelf. Most of the debris was found in canyons descending from the continental slope and in the bathyal plain, with h igh amounts occurring to a depth of more than 500 m. An additional cru ise was undertaken using the manned submersible Cyana (provided by IFR EMER). Sixteen dives (46.07 km distance on the floor) conducted in can yons off Marseilles and Nice (France) ranging from 40 to 1448 m in dep th, enabled us to locate accumulation areas. All these results are int erpreted in terms of hydrological conditions.