The investigation of the benthic food web took place in the Nationalpark Niedersächsisches Wattenmeer (Dorumer) and in Königshafen (Sylt).Experiments were made to test the influence of macrofauna on the microbial benthic community. Natural sediment was placed into cellwells and incubated under controlled conditions for 30 minutes to 24 hours with and without macrograzers. The snail Hydrobia ulvae, the crustacean Corophium volvutator and a mixture of different polychaete species were used as macrograzer. The number of bacteria, cyanobacteria, flagellates (heterotrophic and autotrophic) and diatoms were enumerated after the incubation. Additionally, FLBs (fluorescently labelled bacteria) were added to the experimental samples described above to estimate bacterivory.The results showed no detectable influence of the macrograzers on the abundance of bacteria, cyanobacteria, flagellates and diatoms. The FLB experiment revealed that about 50 to 60% of the bacteria standing stock were consumed each day. There was no difference between the FLB loses in the treatments with and without macrograzers, therefore the consumption of bacteria was mainly due micro- and meiobenthic organisms like flagellates, ciliates, nematodes and copepods.