Biodeposition,respiration, and excretion rates of an introduced clam <Emphasis Type="Italic">Mercenaria mercenaria</Emphasis> in ponds with implications for potential competition with the native clam <Emphasis Type="Italic">Meretrix meretrix</Emphasis> in Shuangtaizi estuary,China

This study aimed to evaluate the potential impacts of an introduced clam Mercenaria mercenaria on estuarine ecosystem, and implications for the niche competition with a native clam Meretrix meretrix. The biodeposition, respiration, and excretion rates of M. mercenaria were determined seasonally using a sediment trap and a closed respirator in field. The biodeposition rates of M. mercenaria were 0.06–0.37 g/ (ind.·d), and the respiration rates were 0.31–14.66 mg/(ind.·d). The ammonia and phosphate excretion rates were 0.18–36.70 and 1.44–14.87 μg/(ind.·d), respectively. The hard clam M. mercenaria may discharge dry deposits up to 2.1×10⁵ t, contribute 18.3 t ammonia and 9.0 t phosphate to culture ponds, and consume 7.9×10³ t O₂ from ponds annually. It suggested that the hard clam M. mercenaria might play an important role in pelagic-benthic coupling in pond ecosystem through biodeposition and excretion. A comparison of the key physiological parameters of the introduced clam M. mercenaria and the native clam Meretrix meretrix suggested that M. mercenaria had a niche similar to that of Meretrix meretrix in Shuangtaizi estuary and might have a potential competition with Meretrix meretrix for habitat and food if M. mercenaria species escaped from the culture pond or artificially released in estuarine ecosystem.