<p>Supporting information</p><p>Table S1 The number of total and effective sequences in each sample obtained by</p><p>Illumina-based 16S rRNA gene sequencing</p><p>Table S2 Correlation analyses of environmental factors and anammox bacterial diversity, abundance and activity measured in the examined drainage ditch sediments</p><p>Fig. S1 The standard curve of qPCR data which was generated from serial 10-fold dilutions of plasmid DNA carrying anammox bacterial 16S rRNA gene fragments.</p><p>Fig. S2 Rarefaction curves of bacterial OTUs (at a 3% similarity cutoff) in sediment samples.</p><p>Fig. S3 The relative abundance of the sequences affiliated with different bacterial phyla to the total number of sequences from the sediment samples at the phylum level. Sequences not classified to any known phylum are included as unassigned. Table S1 The number of total and effective sequences in each sample obtained by</p><p>Illumina-based 16S rRNA gene sequencing</p><p>Sediment Number of total Number of effective Effective sequences samples sequences sequences rate DA 70,795 66,589 93.82% DB 39,697 37,413 94.25% DC 52,684 49,016 93.04% DD 46,409 40,198 86.25% DE 50,909 49,080 96.41% DF 64,785 58,890 91.06%</p><p>Table S2 Correlation analyses of environmental factors and anammox bacterial diversity, abundance and activity measured in the examined drainage ditch sediments </p><p>Environmental Pearson correlation coefficient No. of OTUs Shannon index Chao1 estimator Abundance Activity factors pHa 0.195 0.012 -0.136 0.258 -0.090</p><p>+ a NH4 -N 0.513 0.466 0.514 -0.250 0.130</p><p>- a NO3 -N -0.244 -0.235 -0.250 -0.192 -0.135</p><p>Organic Ca 0.182 0.109 0.516 -0.212 0.071</p><p>+ b NH4 -N -0.063 -0.180 0.300 0.370 0.686</p><p>- b NO3 -N -0.192 -0.185 0.033 -0.050 -0.225 aParameters of the sediments; bparameters of the sediment porewater. Boldface denotes a p value of <0.05, which is typically regarded as significant, as determined by SPSS version 15.0 program (SPSS, Chicago, Illinois, USA). Fig. S1</p><p>7000 DA 6000 DB DC 5000 DD DE 4000 DF s U T O</p><p>3000 f o</p><p>. o</p><p>N 2000</p><p>1000</p><p>0</p><p>0 5000 10000 15000 20000 25000 30000 35000 40000 No. of sequences</p><p>Fig. S2 DA DB DC DD DE DF Ditches</p><p>Fig. S3 </p>