In the late 1960-ties work on the productivity of intertidal benthos at Balgzand was started at NIOZ and this has resulted of a continuous series of benthos density and biomass data on a number of transects in late winter and late summer until present. In order to study the variability in impact of epibenthic predators on especially newly-settled bivalves, in 1983 a series of observations of densities of juvenile epibenthic predators (shrimps and shore crabs) was started on 3 locations, in 1998 extended to 5 locations at Balgzand and still running. As a result of the first inventory a bi-annual sampling programme (late winter/late summer) at three transects was started in 1989 in the Marsdiep tidal basin in the framework of the RWS BIOMON monitoring and carried out by NIOZ until recently.