Carbon, Nitrogen, and Phosphorus Budgets of the Surfclam Mactra veneriformis (Reeve) Based on a Field Study in the Shuangtaizi Estuary, Bohai Sea of China

ABSTRACT Estuaries are characterized by large amounts of nutrient loads, wide intertidal sand flats, and a high biomass of buried filter-feeding bivalves. A field study was designed to determine the role of the buried bivalves in the estuarine nutrient cycle. The biodeposition, respiration, and excretion rates of a dominant surf clam (Mactra veneriformis) in the Shuangtaizi estuary, Bohai Sea of China, were determined seasonally using a sediment trap and a closed respirator. The carbon (C), nitrogen (N), and phosphorus (P) budgets of M. veneriformis for 4 seasons were also modeled. The results showed an obvious seasonality in the physiological rates for the studied clam. The lowest biodeposition rates occurred in winter (0.008 g/individual/day), whereas the highest appeared in summer (0.309 g/individual/day), and were mainly attributed to the effects of water temperature and seston concentration. The maximum respiration rate occurred in summer (30.65 mg/individual/day), whereas the minimum occurred in win...