Using the variation of anammox bacteria community structures as a bio-indicator for anthropogenic/terrestrial nitrogen inputs in the Pearl River Delta (PRD).

The variation of anammox bacteria community composition was evaluated in sediments collected from the Pearl River Delta area with an anthropogenic/terrestrial input gradient. Results indicated that the community composition of anammox bacteria shifted from estuarine environment to the South China Sea deep ocean along with the anthropogenic/terrestrial input gradient, where Scalindua genus of anammox bacteria predominated in the area with less anthropogenic/terrestrial influences, such as in the open oceanic area, while genera of Kuenenia/Brocadia anammox bacteria have higher proportions in the area with higher anthropogenic/terrestrial impacts. The canonical correspondence analysis demonstrated that salinity, organic matter contents, and ratio of NH4 (+) to (NO2 (-)+NO3 (-)) strongly affected the shifting of anammox bacterial community compositions within the same gradients. The results obtained in this study, together with the similar variation of anammox bacteria community structures in other several estuaries in the world, indicated that anammox bacteria might have a habitat-specific distribution pattern according to their living habits, and their community composition could be served as a bio-indicator to monitor the anthropogenic/terrestrial N inputs in coastal environments.