Subtidal hyperbenthos monitoring in function of a foreshore suppletion at the Belgian coast, period 2013-2016

What ecological effects does a foreshore suppletion, and a beach suppletion, have on the marine ecosystem in the intertidal and shallow surf zone ( This dataset contain the hyperbenthic data collected in the subtidal area. The hyperbenthos contain the biota collect in the first meter of the water column, and therefore living in close contact with the bottom and are collected by means of a hyperbenthic sledge. 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 hyperbenthic sledge (with increased weight) by dragging it over the bottom for 15 minutes (1000-1500meter). 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 hyperbenthic sledge consist of a metal frame of 100*40cm, with two nets above each other (0.5m in height each). The content of both nets were kept separately. The samples were fixed by an 8% formaldehyde-seawater solution. All biota were determined and counted to species level were possible and biomass is determined by wet weight. The biomass values from the fish species present was not determined. The density and biomass values were standardized to 1000m².