Program
 
General Session 3: Biological oceanography & global change
 

 
 
1525
Shifts in the community structure and activity of anaerobic ammonium oxidation bacteria along an estuarine salinity gradient
Tuesday 10th @ 1525-1545
Multi-function Hall
Yanling Zheng* , East China Normal University
Lijun Hou, East China Normal University
Min Liu, East China Normal University
Presenter Email: ylzheng@geo.ecnu.edu.cn
Anaerobic ammonium oxidation (anammox) is a major microbial pathway for nitrogen (N) removal in estuarine and coastal environments. However, understanding of anammox bacterial dynamics and associations with anammox activity remains scarce along estuarine salinity gradient. In this study, the diversity, abundance, and activity of anammox bacteria, and their potential contributions to total N2 production in the sediments along the salinity gradient (0.1-33.8) of the Yangtze estuarine and coastal zone were studied using 16S rRNA gene clone library, quantitative PCR assay, and isotope-tracing technique. Phylogenetic analysis showed a significant change in anammox bacterial community structure along the salinity gradient (P<0.01), with the dominant genus shifting from Brocadia in the freshwater region to Scalindua in the open ocean. Anammox bacterial abundance ranged from 3.67กม105 to 8.22กม107 copies 16S rRNA gene g-1 and related significantly with salinity (P<0.05). The anammox activity varied between 0.08 and 6.46 nmol N g-1 h-1 and related closely with anammox bacterial abundance (P<0.01). Contributions of anammox activity to total N loss were highly variable along the salinity gradient, ranging from 5-77%, and were significantly negatively correlated with salinity (P<0.01). Sediment organic matter was also recognized as an important factor in controlling the relative role of anammox to total N2 production in the Yangtze estuarine and coastal zone. Overall, our data demonstrated a biogeographical distribution of anammox bacterial diversity, abundance, and activity along the estuarine salinity gradient, and suggested that salinity is a major environmental control on anammox process in the estuarine and coastal ecosystems.