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The distribution and abundance of large marine debris were investigated on the continental slope and bathyal plain of the northwestern Mediterranean Sea during 3 oceanographic cruises undertaken in June 1994, July 1995 and April 1996. Different types of debris were enumerated, particularly pieces of plastic, plastic and glass bottles, metallic objects, glass and diverse materials including flshing gear. The results showed considerable geographical variation, with concentrations ranging from 0 to 78 pieces of debris ha-' In most stations sampled, plastic bags accounted for a very high percentage (more than 70%) of total debrls. In the Gulf of Lions, only small amounts of debris were collected on the continental shelf. Most of the debris was found in canyons descending from the continental slope and in the bathyal plain, with high amounts occurring to a depth of more than 500 m. An additional cruise was undertaken using the manned submersible Cyana (provided by IFREMER). Sixteen dives (46.07 km distance on the floor) conducted in canyons off Marseilles and Nice (France) ranging from 40 to 1448 m in depth, enabled us to locate accumulation areas. All these results are interpreted in terms of hydrological conditions.

: Acetylcholinesterase (AChE) is used as a specific biomarker of the effects of organophosphorous (OP) and carbamate (C) insecticides on the coastal marine environment. Studies of mixtures (by pairs) of five of these substances showed cumulative, synergistic inhibitory effects in all cases. The strongest synergy was observed in organophosphate-carbamate mixtures (OP-C) and the least in mixtures of substances of the same type (OP-OP, C-C). The intensity of the synergistic effect was directly related to the length of time the enzyme was incubated with the inhibitory mixtures. Among the major organic contaminants of the marine environment, DDT and lindane (organochlorines), as well as atrazine and isoproturon, are not AChE inhibitors and had no effect on the inhibitory action of the OP and C insecticides tested. Among contaminants of metallic origin, zinc chloride, cadmium chloride, tributyltin chloride and methylmercury did not inhibit AChE at the concentrations measured in the different marine compartments (water, sediment, living matter). Mercuric chloride and arsenite had a weak inhibitory action in certain organisms. Zinc chloride, cadmium chloride and arsenic enhanced the inhibitory effects of some OP and C insecticides. The dragonet (Callionymus lyra) proved to be a particularly sensitive target species for monitoring pollutant effects.

Dunng the Bremerhaven Workshop chollnesterase measurements In d a bL~m a n d a llrnanda muscle were evaluated as a monitoring tool to assess the effect of pollutants along a 360 km transect In the North Sea, and around a dnlling s~t e The baslc properties of chol~nesterases, together wlth t h e~r natural vanabihty related to sex and size, were lnvestlgated The results show the presence of at least 2 d~fferent enzymes, acetylcholinesterase and butyrylchol~nesterase w t h h~g h actlv~tles In b r a n , muscle and l~v e r No varlatlon was observed In relation to sex or slze The act~vity of both acetylcholinesterase and butyrylcholinesterase was depressed In nearshore statlons along the transect and no variation was observed around the dr~lhng slte The K,, of acetylchol~nesterase from muscle of d a b varied along the transect The results lead us to Interpret enzyme var~ation as the result of effects of neurotoxic compounds coming from the Elbe and Weser rlvers into the German B~g h t and validate cholinesterase activlty as a tool for biological monltonng at sea

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