Goals Shipwrecks provide increased habitat complexity, and hence attract and harbour many more species than the relatively homogenous soft substrates in their vicinity. Hard substrates offer an opportunity for sessile epifauna to settle and a refugium from predators for mobile epifauna and nekton. Several wrecks are candidates for the designation of Marine Protected Areas in Belgium. They can be used as a model for other hard substrates, like the foundations of windmills that will be built in the Belgian part of the North Sea in the near future. Wrecks form an impediment to fishing, and provide a model for non-fishing areas. One of the objectives of this study is to compare the soft-bottom fauna of the open areas with the less-intensely trawled bottoms adjacent to the wrecks. Methods Five wrecks located in Belgian waters will be sampled for biotic and abiotic data at different periods of the year. The meiofauna, macrofauna and epifauna of the wrecks will be studied by direct observations, photographs and sampling by divers. Macrofauna in the soft substrates around the wreck will be sampled in situ by S.C.U. B.A. using suction dredger and cores. Slow moving sessile fauna will be sampled by scraping selected quadrats. Small swimming and/or nocturnal fauna will be caught by means of baited traps. Large swimming epifauna will be sampled visually in situ. Density, biomass, and species composition of the benthic communities of the different wrecks will be described, and biodiversity will be estimated. Within each wreck, studies will be conducted in order to compare different factors affecting biodiversity: period of the year (i.e. seasonal effect), orientation of the sampled station (i.e. horizontal and vertical surfaces), depths of the station and other abiotic factors around the wrecks such as water temperature, conductivity, irradiance, currents, turbidity. Historical data sets and mathematical models will also be used. By means of multivariate statistical techniques, the ecological communities of the wrecks will be compared to each other and to those of the surrounding sediments. The species assemblages will also be compared with those of natural and artificial hard substrates in Belgium, northern France and eastern England (both intertidal and subtidal structures: literature survey and input from end-user committee).