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International audienceBiogenic reefs composed of the tube-building polychaete Lanice conchilega are important from a conservationpoint of view because they noticeably increase the biodiversity in otherwise species poorenvironments. However, up to now, little or no attention has been paid to the intertidal epi- andhyperbenthic communities associated with the reefs. Therefore, this is the first study which focuses onthe effect of L. conchilega reefs on the entire bentho-pelagic community at two different locations.Environmental variables were measured and macro-, epi- and hyperbenthic communities were sampledwithin a L. conchilega reef and a control area at two locations in France: the bay of the Mont Saint-Michel(BMSM) and Boulogne-sur-Mer (Boulogne). The effect of the reef presence on the benthic communitywas studied with a 3-factor (Reef, Location and Period) Permanova. In addition, the relationship betweenthe benthic community and the environmental variables was investigated using Distance-based linearmodels (DistLM). Most collected organisms were sampled in the reef area (macrobenthos: 91%, epibenthos:81% and hyperbenthos: 78.5%) indicating that, independent of the location, the L. conchilegareefs positively affect all three associated benthic communities. However, the extent of the effect seemsto be most pronounced for the macrobenthos and less distinct in case of the hyperbenthos. The macro-,and epibenthos are mainly structured by biotic variables (L. conchilega density and macrobenthic foodavailability respectively), while the hyperbenthos is rather structured by environmental variables. Ingeneral, L. conchilega reefs do not only affect abundances and diversity but they substantially steer thestructure of the intertidal benthic sandy beach ecosystem

In 1997 the Flemish Environmental Agency (FEA) started a monitoring program "Pesticides in Rain in Flanders, Belgium". The original purpose of the monitoring program was to examine the possible occurrence of dichlorvos in rainwater and subsequent deposition. However, it was thought necessary from the beginning to monitor a wide range of pesticides. During the first year some 62 pesticides and metabolites and 9 polychlorinated biphenyls, were monitored at 4 locations. Nowadays the monitoring program has grown up to more than 100 pesticides and metabolites and 11 polychlorinated biphenyls examined at 8 different locations. Rainwater is collected continuously and samples are examined for pesticides and PCB's on a weekly basis. In agreement with other European studies pesticides are found in rainwater samples during times of application. Pesticides which are most frequently detected are [small alpha]-, [small beta]-endosulfan and endosulfan sulfate, [gamma]-HCH (lindane), dichlorvos, atrazine, diuron, DNOC, glyphosate and AMPA and isoproturon. Furthermore it was seen that most pesticides showed a deposition pattern related to local spraying operations.

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The tube-building polychaete Lanice conchilega can form dense populations, often called reefs, which promote benthic community change and constitute feeding grounds for secondary consumers. The aim of this study was to quantify the role of the L. conchilega reef of the Bay of the Mont Saint-Michel (BMSM) for feeding waders, by combining macrobenthos data, bird counts and bird diet information. Wader densities in the reef were on average 46.6 times higher than in non-reef areas. According to faecal analyses, waders in the reef mainly selected the accompanying fauna and especially crustaceans. The attractiveness of the reef to feeding birds may be largely explained by the high abundance, richness and biomass of macrobenthic species in the reef compared with the rest of the BMSM