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In 2013, the second year of the “Slak-in-Du” (Snails-in-Dunes) project, the Eastern part of the Belgian coast (UTM 10 x 10 km2 squares ES18, ES28 and ES29, and mainly the UTM square ES28), has been further investigated. Apart from this also two other locations, named Schuddebeurze (at Middelkerke, in the central part of the Belgian coast, UTM square DS86) and Calmeynbos (at De Panne, West Coast, UTM square DS76) were investigated. The already quite interesting list of species observed at each of these two locations, will undoubtedly be further extended when they will be investigated in more detail in the coming years. At present a total of 81 different species of molluscs have already been observed within the project. The results obtained for the Belgian East Coast, which has been investigated quite intensively in 2012 and 2013, are very positive. A total of 80 different species of molluscs were observed, 40 of which were added in 2013. Noteworthy are the terrestrial snails Truncatellina cylindrica, Vertigo antivertigo and Vertigo pusilla, as well as the freshwater snail Aplexa hypnorum. Further, two very important species of brackish water molluscs have been observed, i.e. Auriculinella bidentata (in “Zwin Noord”) and Cerastoderma lamarcki (in the “Dievegat”). The observation of the brackish water cockle Cerastoderma lamarcki in the Dievegat, one of the very few locations where this in Belgium very threatened species still occurs, is of great importance. This certainly adds to the arguments against the planned disappearance of the Dievegat, a unique brackish water biotope and very important piece of nature. We therefore strongly suggest the Dievegat be maintained in its present state when the nature reserve “Het Zwin” will be extended in the coming years. The efficiency of the second year of the “Slak-in-Du” project was significantly higher than in 2012. This is due to the larger number of field trips and participants, the increased experience of the participants (training effect), de greater attention that was paid to slugs and freshwater molluscs, and the fact that this year soil samples were taken at all visited locations thereby assuring that the smallest species were not overlooked anymore. Even after two years of field work and study, seven species of land snails that have not been reported anymore at the Belgian East Coast since 1950, have also in this second year of the project not yet been observed. These are: Abida secale, Cecilioides acicula, Balea perversa, Monacha cartusiana, Helix itala itala, Candidula unifasciata and Arianta arbustorum. Further, Cernuella aginnica, a species that has frequently not been observed at the Belgian coast during the last about twenty years and may become endangered, has not been observed in 2013 (although in 2012 a single empty shell was found). All this requires for further detailed investigations. Finally, also the slugs, which have received already significantly more attention in 2013 in comparison to the previous year, still deserve to be searched for more actively during the field work. Nevertheless, after two years the “Slak-in-Du” project has been very successful and expectations have been entirely met already for the Belgian East Coast which has been the focus of the project till now. Indeed, in 2012 en 2013 a total of 32 species have been reported for the first time for one or more of the three UTM squares at the East Coast, nine of which are even reported for the very time for the entire East Coast. In addition, another 10 species have been reported for the first time since 1950. In 2014 and 2015 the project will concentrate mainly on the central part of the Belgian coast line.

The Slak-in-Du (Snails in the Dunes) project aims at establishing, over a period of about six years, a new inventory of the molluscan fauna in the Belgian coastal dunes area. In the first year of the project the eastern part of the Belgian coast was investigated, i.e. the region east of the harbor of Zeebrugge. About 20 persons have contributed in one way or another. The results are very satisfactorily: A total of 30 species of land snails (among which 5 species of slugs), but also 6 species of freshwater molluscs and 5 species preferring brackish waters were observed. More than half of the species of land snails observed are reported for the first time since 1950 or even for the first time ever for the UTM (Universal Transverse Mercator) 10 x 10 km squares that were investigated, i.e. ES18, ES28 en ES29. The most important of these is undoubtedly Vertigo angustior, a protected species which was found for the first time in more than 50 years at the eastern part of the Belgian coast and for the first time ever in the nature reserve “Het Zwin”. Four other species are reported for the first time in the region that was investigated, i.e. Zonitoides nitidus, Cochlicella acuta, Cernuella cisalpina (= C. jonica) and Alinda biplicata biplicata. The latter had, moreover, never been observed before in the Belgian coastal area. Five species were found rather frequently, i.e. Monacha cantiana, Candidula intersecta, Cernuella virgata, Theba pisana and Cepaea nemoralis. The data that were collected further clearly show that Cochlicella acuta and Theba pisana pisana have by now spread along the entire Belgian coast. On the other hand, several species that are thought to be in decline at the Belgian coast, i.e. Monacha cartusiana, Helicella itala itala, Candidula gigaxii, and Candidula unifasciata unifasciata, have not been observed at all. As only one specimen of Cernuella aginnica was found, also this species is probably in decline. Since only few freshwater habitats occurred in the areas that were investigated in 2012 only a limited number of freshwater species is reported here. Finally, as to brackish water snails, the very rare species Limapontia depressa and Assiminea grayana were found in the “Bay of Heist”, while one specimen of Ecrobia ventrosa was observed alive in the nature reserve “Het Zwin”.

The distribution of Ensis directus in the north of France was studied. After the first reports of Ensis directus on the beach of Bray-Dunes in January and February 1988 (KERCKHOF & DUMOULIN, 1988a), it bas moved very fast to the south. At present the species is very common between the Belgian-French border and Calais. It seems to be absent however between Sangatte and Bou1ogne-sur-Mer, as apparently also the other Ensis species as well as Solen marginatus ! It is not yet clear why Ensis directus would not live in the sandy environment of the beaches of Wissant and Wimereux. Collections on beaches south of Boulogne-sur-Mer show no evidence that the conclusion of an earlier report (SEVERIJNS & GILLES, 1993), namely that Berck-Plage is very probably the most southern European location where Ensis directus lives at this moment, does not have to be changed. Finally, the dataset seems to suggest that Ensis directus moves southward much faster when the coastline is directed north-south than when it is directed east-west. The reason for this is not yet clear .It might e.g. be related to the directions of the ocean currents. It is further probably that the rocky region around the Cap Griz-Nez has slowed down the spreading of Ensis directus to the south as well.