In the water-sediment interface above the Mulinia sp. and Venus antiqua banks at the tidal flat of Yaldad Bay, rich bacterial populations were found throughout the year, whilst highest microalgae densities were found during spring-summer season. Harpacticoid copepods at both sites, were restricted to the upper centimeter sediment layer. Research on this community was conducted from March 1990 to January 1992, having found that harpacticoid copepod species with constant food source throughout the year, also presented constant populational densities and reproductive activity (e. g. Amphiascopsis cinctus, bacterial feeder), whilst those species with strong fluctuating food, presented strong oscillations of numerical density and reproductive activity (e. g. Laophonte parvula, species feeding on microalgae). Furthermore the low density of harpacticoid copepods found at Yaldad, does not suggest them to be a major food resource for the epibenthic and pelagic macrofauna.