The effect of clams (Tapes philippinarum) on changes in microbial community structure in tidal flat sediment mesocosms, based on quinone profiles

To elucidate the relationship between macrobiotics and microorganisms on pollutant degradation in tidal flat sediment, changes in water quality were monitored and shifts in microbial community structure were evaluated using the quinone profile method in mesocosms of tidal and subtidal flat sediment with and without clams. Dissolved organic carbon (DOC) and NH4-N concentrations in pore water of tidal sediment with clams were higher than in sediment without clams over a 24 h period. This is explained by the ability of clams to consume particulate organic matter and excrete DOC and NH4-N. Otherwise, the effect of clams was relatively low in subtidal sediments. The presence of clams and tidal conditions changed the predominant quinone species in both sediments. Ubiquinone with 10-isoprene unit (UQ-10) and menaquinone with 6-isoprene unit (MK-6) were predominant quinone species in tidal and subtidal sediment with clams, respectively. The effect of clams on changes in microbial community structure in tidal sediment was more rapid than in subtidal sediment. The differences in microbial community structure in tidal sediment with and without clams were mainly due to the profile changes in UQ-8, UQ-9, UQ-10, MK-7 (H-8) and MK-9 (H-2)-containing bacteria. (C) 2004 Elsevier B.V. All rights reserved.