In-situ Measurement of the Removal Flux of Particulate Organic Matter by the two Dominant Clams (Ruditapes philippinarum and Mactra veneriformis) in Korean Tidal Flats

초록

A manila clam Ruditapes philippinarum and a mactrid bivalve Mactra veneriformis are suspension feeders inhabited densely in many Korean tidal flats. Their feeding activity is performed by pumping and filtering large volume of water through the gills and therefore, enhances a flux of particulate organic matter from the water column to the benthic system. The extent of the water purification function can be inferred through measuring the clearance rate or filtration rate of the bivalves. To measure the flux of POM under the harsh physical conditions in the hypertidal flat (average tidal rage >6m, tidal current >1m/s), an in situ benthic cylindrical chamber designed for bare tidal flat and long term incubation was used. Net clearance rate of the bivalve R. philippinarum (shell length ca. 4) was measured as 0.45 l/h/g meat dry wt. Therefore the daily removal rate of POM was calculated as 5,374 POC and 340 PON in Seonjae manila clam habitat with an area of 4. It can be converted in yearly rate as 327 ton POC/ and 21 ton PON/. Net clearance rate of the bivalve Mactra veneriformis (shell length ca. 4) was measured as 0.51 l/h/g meat dry wt. Then, the daily removal rate of POM was calculated as 12,154 POC and 1,237 PON in Songdo tidal flat with an area of 10. It can be converted in yearly rate as 444 ton POC/ and 45 ton PON/.