Online Appendix s1

1 Online Appendix 2 Online Appendix Table 1. Twelve study locations, with connected sites (natural floodplain 3 wetlands hydrologically connected to the river) and isolated sites (isolated from the river by 4 levees), in the Wusuli River watershed, Northeastern China, and associated physical and 5 chemical variables (errors around values (SE)). 6 Online Appendix Table 2 The average hydrological and vegetation characterization of the 7 Wusuli River during May to August from year of 1956 to 2005.

8 Online Appendix Fig 3. Redundancy analysis (RDA) concerns snail species and 9 environmental variables. Depth: water depth of wetlands; DO: dissolved oxygen, TN: total 10 nitrogen, TP: total phosphorus. Species : 1.Acroloxus lacustris (Linnaeus), 2.Bithynia 11 ussuriensis Büttner & Ehrmann, 3.Parafossarulus striatulus (Benson), 4.Galba pervia 12 (Martens), 5.Radix auricularia (Linnaeus), 6.Radix balthica (Linnaeus), 7.Radix lagotis 13 (Schrank), 8.Radix latispira Yen, 9.Radix peregra (Müller), 10.Radix plicatula (Benson), 14 11.Semisulcospira amurensis (Gerstfeldt), 12.Semisulcospira libertina (Gould), 13.Aplexa 15 hypnorum (Linnaeus), 14.Physa acuta Draparnaud, 15.Physa fontinalis (Linnaeus), 16 16.Gyraulus albus (Müller), 17.Gyraulus centrifugus (Westerlund), 18.Gyraulus gredleri 17 (Bielz) Gredler, 19.Helicorbis cantori (Benson), 20.Planorbis corneus (Linnaeus), 18 21.Segmentina hemisphaerula (Benson), 22.Segmentina nitida (Müller), 23.Pupilla sp., 19 24.Succinea sp., 25.Vallonia sp., 26.Valvata cristata Müller, 27.Valvata piscinalis (Müller), 20 28.Valvata sibirica Middendorff, 29.Cipangopaludina ussuriensis (Gerstfeldt).

1 1 Online Appendix Table 1. Twelve study locations, with connected sites (natural floodplain wetlands hydrologically connected to the river) and isolated

2 sites (isolated from the river by levees), in the Wusuli River watershed, Northeastern China, and associated physical and chemical variables (errors

3 around values (SE)).

No. Wetland Name Coordinates River section pH DO (mg/L) Depth(cm) Cl-(mg/L) -N(mg/L) -N(mg/L) TN(mg/L) TP(mg/L)

0.21 0.243 0.403 0.356 8.84(0.25 0.21(0.04) 0.24(0.01) 0.40(0.04) 0.36(0.03) Site1 Donghe (C) N 48°07´41.06", 11.30(0.16) 25(1.73) 15.74(4.22) Downstream ) Donghe (I) E 134°34´32.75" 9.89(0.10) 10(1.15) 18.61(7.66) 0.23(0.03) 0.19(0.02) 0.57(0.03) 0.20(0.04) 8.60(0.27) 8.71(0.05 0.14(0.06) 0.20(0.01) 0.47(0.03) 0.22(0.03) Site2 Dongsheng (C) N 48°07´02.69", 8.70(0.32) 30(2.89) 69.94(1.39) Downstream ) 0.11(0.02) 0.29(0.03) 0.49(0.03) 0.38(0.04) Dongsheng (I) E 134°32´42.59" 10.55(0.10) 40(2.89) 80.78(20.49) 8.48(0.08) 8.01(0.29 6.09(1.24) 0.28(0.06) 0.24(0.01) 0.53(0.05) 0.28(0.02) Site3 Bagai (C) N 48°09´38.30", 9.39(0.07) 40(2.31) 45.18(3.98) Downstream ) 0.08(0.04) 0.24(0.02) 0.49(0.05) 0.27(0.02) Bagai (I) E 134°37´31.27" 15.21(0.61) 25(0.58) 9.33(0.36) 7.64(0.16 0.09(0.04) 0.22(0.01) 0.56(0.05) 0.31(0.04) Site4 Yaoliangzi (C) N 48°12´42.34", 10.20(0.11) 20(5.29) 1.90(0.24) Downstream ) 0.16(0.04) 0.20(0.04) 0.41(0.05) 0.25(0.05) Yaoliangzi (I) E 134°38´56.49" 8.32(0.07) 30(3.46) 3.19(0.39) 7.69(0.07) 8.91(0.08 0.13(0.03) 0.25(0.02) 0.41(0.09) 0.31(0.02) Site5 Raohe1 (C) N 46°46´59.73", 9.70(0.10) 25(1.73) 12.64(0.41) Mid-reach ) 0.16(0.03) 0.21(0.01) 1.77(0.34) 0.26(0.03) Raohe1 (I) E 134°01´19.74" 19.02(0.33) 10(1.0) 33.70(1.55) 9.95(0.10) 9.02(0.07 0.12(0.04) 0.36(0.02) 0.61(0.13) 0.26(0.02) Site6 Raohe2 (C) N 46°46´10.62", 10.87(0.02) 16.7(1.6) 13.51(1.35) Mid-reach ) 0.05(0.01) 0.20(0.02) 0.48(0.08) 0.28(0.04) Raohe2 (I) E 134°01´06.99" 11.82(0.08) 20(2.0) 11.94(0.99) 9.08(0.03) 25(3.61) 0.01(0.04) 0.29(0.01) 0.33(0.07) 0.32(0.03) Site7 Raohe3 (C) N 46°43´39.92", 9.11(0.04) 9.69(0.20) 11.57(0.36) Mid-reach 30(1.73) Raohe3 (I) E 134°00´47.72" 8.89(0.14) 8.83(0.29) 6.11(1.35) 0.05(0.03) 0.23(0.01) 0.26(0.46) 0.27(0.03) 8.47(0.14 0.11(0.01) 0.29(0.03) 0.18(0.12) 0.24(0.02) Site8 Raohe4 (C) N 46°43´28.09", 9.43(0.32) 40(2.89) 4.82 (0.68) Mid-reach ) 0.07(0.03) 0.25(0.02) 0.59(0.41) 0.17 (0.03) Raohe4 (I) E 134°00´42.35" 10.44(0.42) 25(2.89) 3.33(0.52) 7.72(0.24) Site9 Songacha1 (C) N 45°15´26.79", Headwater 8.12(0.12 6.03(0.04) 15(2.89) 10.39(1.54) 0.08(0.06) 0.21(0.06) 0.48(0.09) 0.27(0.02) Songacha1 (I) 15(1.15) 26.07(3.32) E 133°05´13.93" ) 8.54(0.14)

2 0.10(0.02) 0.28(0.02) 0.30(0.08) 0.31(0.01) 8.30(0.08)

7.99(0.05 0.05(0.02) 0.23(0.01) 0.33(0.15) 0.24(0.03) Site10 Songacha2 (C) N 45°15´49.44", 6.98(0.29) 15(2) 9.10(0.24) Headwater ) 0.07(0.03) 0.34(0.03) 0.59(0.14) 0.30(0.02) Songacha2 (I) E 133°05´22.10" 8.24(0.22) 13.3(1.6) 35.97(0.28) 8.47(0.02) Site11 N 47°31´56.97", 0.22(0.07) 0.39(0.09) 0.54(0.07) 0.25(0.01) Bielahong (C) Tributary 8.41(0.17) 12.55(0.66) 20(1.15) 2.52(0.51) E 133°53´04.37"

Site12 N 47°16´04.12", 0.04(0.04) 0.27(0.04) 0.42(0.08) 0.32(0.03) Naoli (C) Tributary 8.91(0.24) 9.70(0.10) 20(1.73) 8.64(0.96) E 133°45´50.90" 1

9 Online Appendix Table 2 The average hydrological and vegetation characterization of the Wusuli River during May to August from year of 1956 to 2005.

Hydrological Station Site Coordinates River Section Water level (m) Runoff (m3/s) Catchment area Dominant vegetation composition

3 (104km2)

Hutou N 45°59′, Headwate 54.03 501.0 6.60 Calamagrostis angustifolia Kom., Glyceria E 133°39′ r spiculosa (Schmidt.) Roshev, Phragmites australis (Cav.) Trin. ex Steud.

Carex appendiculata (Trautv.) Kuekenth., Carex Raohe N 46°48′, Mid-reach 46.68 735.7 10.0 lasiocarpa Ehrh., Carex meyerina Kunth, E 134°01′ Phragmites australis (Cav.) Trin. ex Steud.

Downstre Carex appendiculata (Trautv.) Kuekenth., Carex Haiqing N 47°53′, 37.66 1315.9 18.0 am lasiocarpa Ehrh., Carex meyeriana Kunth E 134°39′

N 47°55´, Carex lasiocarpa Ehrh., Carex pseudocuraica F. Bielahongr Tributary 37.17 8.42 0.43 Schmidt, Typha angustifolia L. E 134°28´

Calamagrostis angustifolia Kom., Carex N 46°13´, lasiocarpa Ehrh., Carex pseudocuraica F. Naoli Tributary 40.15 62.79 2.40 Schmidt, Phragmites australis (Cav.) Trin. ex E 133°20´ Steud.

4 0.8 pH

TN DO S24 TP S8 S21 S13 S7 S12 - S22 Cl S25 S3 S23 S4 S20 S16 S5 S1 S15 S14 S27 + S17 𝐍𝐎− − 𝐍 𝐍𝐇𝟒 − 𝐍 S11 𝟑 S29 S9 S28

S6 S10

S26 S19 S18 S2 Depth

-0.8 1.0

1 2 Online Appendix Fig 3. Redundancy analysis (RDA) concerns snail species and 3 environmental variables. Depth: water depth of wetlands; DO: dissolved oxygen, TN: total 4 nitrogen, TP: total phosphorus. Species :1.Acroloxus lacustris (Linnaeus), 2.Bithynia 5 ussuriensis Büttner & Ehrmann, 3.Parafossarulus striatulus (Benson), 4.Galba pervia 6 (Martens), 5.Radix auricularia (Linnaeus), 6.Radix balthica (Linnaeus), 7.Radix lagotis 7 (Schrank), 8.Radix latispira Yen, 9.Radix peregra (Müller), 10.Radix plicatula (Benson), 8 11.Semisulcospira amurensis (Gerstfeldt), 12.Semisulcospira libertina (Gould), 13.Aplexa 9 hypnorum (Linnaeus), 14.Physa acuta Draparnaud, 15.Physa fontinalis (Linnaeus), 10 16.Gyraulus albus (Müller), 17.Gyraulus centrifugus (Westerlund), 18. Gyraulus gredleri 11 (Bielz) Gredler, 19.Helicorbis cantori (Benson), 20.Planorbis corneus (Linnaeus), 12 21.Segmentina hemisphaerula (Benson), 22.Segmentina nitida (Müller), 23.Pupilla sp., 13 24.Succinea sp., 25.Vallonia sp., 26.Valvata cristata Müller, 27.Valvata piscinalis (Müller), 14 28.Valvata sibirica Middendorff, 29.Cipangopaludina ussuriensis (Gerstfeldt).