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Table 1 Environmental variables across the 62 sampling sites in the wet and dry seasons. **P < 0.01 or *P < 0.05 indicate the significant difference among seasons based on Mann-Whitney U tests

From: Environmental filtering and spatial processes equally contributed to macroinvertebrate metacommunity dynamics in the highly urbanized river networks in Shenzhen, South China

  Wet season Dry season F P
Min–Max Mean Min–Max Mean
Water temperature (°C) WT ** 14.10–34.00 28.57 ± 3.58 14.30–26.8 21.50 ± 2.67 126.27 0.000
pH pH ** 6.76–8.76 7.30 ± 0.33 2.71–9.13 7.72 ± 0.77 8.01 0.005
Dissolved oxygen (mg/L) DO 0.13–9.90 5.35 ± 2.25 1.54–9.41 5.84 ± 2.06 2.19 0.142
Conductivity (s/cm) Cond 27.50–1628.00 349.99 ± 295.36 27.00–6250.00 545.22 ± 1010.27 1.48 0.226
Turbidity (NTU) Tur ** 1.14–271.00 38.03 ± 51.30 0.56–81.90 9.62 ± 12.54 37.48 0.000
River width (m) RW ** 3.00–220.00 40.15 ± 46.26 0.60–101.00 21.01 ± 19.81 9.14 0.003
Water depth (m) WD 0.02–5.00 0.73 ± 1.06 0.05–3.50 0.47 ± 0.69 2.97 0.088
Velocity (m/S) Vel 0.01–0.81 0.24 ± 0.18 0.01–0.90 0.25 ± 0.20 0.17 0.681
Div_substrate Div_substrate 0.00–0.73 0.23 ± 0.26 0.00–0.73 0.22 ± 0.27 0.04 0.852
Percentage of boulder %Boulder 0.00–100.00 9.68 ± 23.73 0.00–100.00 9.92 ± 24.97 0.00 0.952
Percentage of cobble %Cobble 0.00–90.00 11.77 ± 25.16 0.00–90.00 10.08 ± 21.93 0.05 0.825
Percentage of pebble %Pebble 0.00–85.00 8.87 ± 17.16 0.00–90.00 9.52 ± 17.94 0.01 0.935
Percentage of gravel %Gravel 0.00–95.00 9.44 ± 18.36 0.00–95.00 8.26 ± 18.25 0.39 0.531
Percentage of sand and silt %Sand and silt 0.00–100.00 59.92 ± 44.56 0.00–100.00 62.18 ± 43.82 0.12 0.736
Permanganate index (mg/L) PI 0.90–12.30 3.04 ± 2.09 0.50–5.10 2.56 ± 1.14 1.85 0.176
Chemical oxygen demand (mg/L) CODCr 6.00–69.80 13.81 ± 14.32 5.00–25.00 10.58 ± 4.99 0.65 0.422
Biochemical oxygen demand over 5 days (mg/L) BOD5 0.50–27.30 2.79 ± 4.75 0.50–5.90 2.13 ± 1.26 0.03 0.859
Ammonium nitrogen (mg/L) NH4+-N * 0.03–17.90 2.14 ± 3.93 0.03–4.10 0.79 ± 0.83 5.42 0.022
Total phosphorus (mg/L) TP * 0.00–1.72 0.27 ± 0.41 0.01–0.39 0.15 ± 0.11 4.05 0.046
Total nitrogen (mg/L) TN 0.13–18.32 4.99 ± 4.82 0.05–18.22 5.83 ± 5.04 0.87 0.353