g. Herrmann et al. 1999, Humphreys et

al. 1999, Schwarzer 2010). Mining of the sea bed affects the environment in a number of ways. The type and scope of changes selleck screening library in the marine environment, mainly on the sea bottom, is determined by the method of clastic (gravel and sand) material extraction. Stationary extraction, either by bucket or suction dredgers, results in extensive depressions/pits in the sea bottom of diameters exceeding 100 m and depths of over 10 m. Trailer suction hopper dredging leaves a trace in the form of 1 or 2 parallel furrows 0.2 to 0.5 m deep and 2 to 3 m wide. By this method only a thin surface layer of deposits is removed from a large surface of the bottom. Both types of extraction disturb the marine environment in that they: – remove a layer of deposits which constitutes a habitat for benthic organisms, resulting in a reduction of biomass, In many countries the effect of the exploitation of clastic resources on the marine

check details environment is extensively investigated, and special attention is given to the rate of resettlement of benthic organisms in the dredged pits (e.g. ICES 2001, Boyd et al. 2004, Cooper et al. 2005) and the rate of physical seabed regeneration (Kubicki et al. 2007, Manso et al. 2010). In Poland investigations of the effect of excavating gravel from the seabed were carried out on the Slupsk Bank in 1988–1989 (Gajewski & Uścinowicz 1993). In spite of the increasing amounts of sand and gravel extracted, however, no further scientific investigations were carried out. The growing scale of offshore dredging has triggered an international exchange of experience and information on the impact of these activities, the minimising of their negative effects, and the development of monitoring methodology. These were the objectives of the COST 638 Action ‘Investigating and managing Astemizole the impacts of marine

sand and gravel extraction and use’. The research project ‘Impact of sand extraction from the bottom of the southern Baltic Sea on seabed structure and meio- and macrobenthos communities’, financed by the Ministry of Science and Higher Education (grant No. 305/N-COST/2008/0), was connected with the objectives of the above-mentioned COST Action. This paper presents the results of investigations of the geological structure and the physical effects of sand extraction in the study area, concerning especially: – the origin and age of the extracted sand and its immediate substratum, The investigations were carried out in the south-eastern part of the Baltic Sea, in the shallow water area north of Władysławowo (Figure 1). It was known that medium and coarse sand is present on the seabed surface (Pikies & Jurowska 1992). More detailed investigations of the area were ordered in 1992 by the Maritime Office in Gdynia.