The strongest earthquake of 2011 hit eastern Japan and triggered the Tohoku tsunami that severely affected the northeastern coast of Japan. The coastal soil ecology and seabird colonies were significantly changed by the tsunami. We investigated the physicochemical dynamics of ornithogenic nitrogen derived from the uric acid in seabird feces in soil splashed or flooded by the tsunami. The analyses suggested that soil leaching in areas flooded by the tsunami led to a change in ornithogenic nitrogen, particularly suppression of nitrification. In the present study, we performed next-generation sequencing (NGS) and statistical analyses to compare the bacterial community structures of ornithogenic soil in areas splashed or flooded by the tsunami, and identified how the suppression of nitrification affected the microbes in ornithogenic soils. The statistical analyses based on NGS revealed that the dynamics of NO3−-N in the splashed soils was affected by the structure of the microbial community involved in denitrification and/or dissimilatory nitrate reduction to ammonium, and that the dynamics of NH4+-N in the flooded soils was not affected by nitrifying bacteria. The results of the statistical analysis also indicated that the differences in microbial community composition detected between splashed and flooded soils affected their nitrogen cycling. Our results provide insights into the microbial effect of nitrogen cycling in soil environments affected by the tsunami.
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