This dataset contains the epibenthos and demersal fish data collected in the subtidal area. The epibenthic and demersal fish fauna are the biota living on the sea bottom and which are catched with a bottom trawl in this study. The sampling design for the monitoring is following the BACI-design (Before After Control Impact), with a control area with similar habitat characteristics outside the influence of the suppletion activity. There is sampled before the suppletion and in the following two years after suppletion. In this BACI-monitoring, the seasonal aspect is taken into account, by taking samples in spring (March) and autumn (September). In the subtidal area, three depth strata were determined to investigated the influence of the suppletion outside the suppletion area. Stratum a (between low water line and -2m TAW) is the area were the foreshore suppletion is executed. Stratum b and c are taken respectively the depth zones -3m to -4m and -5m to -6m TAW. The amount of sampling locations was determined by the client and contains six tracks for each sampling moment. In each stratum two tracks were taken and the sampling start at the moment of high tide, starting at stratum a. The samples were taken with a 3m beam trawl (22mm mesh size) and a light chain at the bottom of the net. The beam was dragged over the bottom for 15 minutes (1000-1500m). This was done with a constant speed and in line with the currents. The exact distance of the track was determined by calculating the distance between the start- and stop coordinate. The content of the net was worked out immediately by determining and counting the species. The entire catch was handled for determining and counting the fish species, whereas the epifauna was mostly handled by sub-sampling (minimum volume of 2 L). The length of the fish species were measured and the biomass of the epibenthos was based on wet weight measurements. The density and biomass values were standardized to 1000m².

What ecological effects does a foreshore suppletion, and a beach suppletion, have on the marine ecosystem in the intertidal and shallow surf zone (6 m depth)? The foreshore suppletion (400.000m³) was by means of an experimental set-up in the shallow coastal zone (-1 to -2m TAW) of Mariakerke. Beside it, a beach nourishment was conducted at Mariakerke (681243m³) and Middelkerke (968754m³). For the Mariakerke area, we collect biological and sedimentological samples in the impact area and in a control area (Bredene), before as after the suppletion, whereas for Middelkerke only the data after suppletion was part of the study. We monitor the marine ecosystem with a focus on the fauna within the sediment (macrofauna) and on the sediment (hyperbenthos, epi- and demersal fish fauna) in the intertidal zone and subtidal zone.