The trophic interactions between primary consumers and the organic matter sources in a man-made intertidal ecosystem were investigated. The most representative invertebrates that occupied the different habitat types tend to use similar food sources, namely benthic diatoms and suspended particulate or sedimentary organic matter, although they do so in different proportions. Fucus vesiculosus was abundant on the rocky substrate but this macroalga nor its epiphytes contributed importantly to the diet of the primary consumers inhabiting these assemblages. In contrast, benthic diatoms from the nearby mudflat were directly used as a food source because of their re-suspension in the water and transport by the tide to the artificial rocky shore. The results suggested that the trophic pathways in this intertidal environment were relatively simple.