Abstract The food chain dynamics of the edible mussel Mytilus edulis L., the American oyster Crassostrea virginica (Gmelin) and the hard clam Mercenaria mercenaria (L.) were investigated in large experimental tanks with flowing, filtered sea water and controlled addition of phytoplankton. The feeding rate of the mussel (5.36 μg carbon removed/l/g C animal was higher than that of the oyster (3.92) and clam (3.03) but the ecological efficiencies (net production/ingested food) × 100 of the clam (23.69 %) and the oyster (18.38 %) were higher than that of the mussel (10.01 %). The food chain efficiencies (net production/available food) were lower than the ecological efficiencies, suggesting under-exploitation of the available food. The clam, although having a lower feeding rate, was more efficient in utilizing the food it filtered and so showed the highest net production. The rates (μg-at/l/g C animal) of regeneration of nutrients, especially total inorganic nitrogen (mussel, 2.1723 × 10 −3; oyster, 7.4270 × 10 −3; and clam, 8.1750 × 10 −3) along with reported high biodeposition rates of bivalves suggest that multi-species aquaculture systems would be more efficient and productive than one-species systems.