Table 1.
Total numbers of the six snail species sampled in the five Ruhr lakes in 2012 and 2013, with the number of examined snails, infected snails, overall prevalence of trematode infections (% of infected snails in the pooled samples), and number of samples used in the component community analyses.
| Lake | Baldeneysee | Hengsteysee | Sorpetalsperre | Hennetalsperre | Versetalsperre | Total | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Year | 2012 | 2013 | Total | 2012 | 2013 | Total | 2012 | 2013 | Total | 2012 | 2013 | Total | 2012 | 2013 | Total | ||
| Lymnaeidae | |||||||||||||||||
| Radix auricularia | No. examined | 275 | 91 | 366 | 596 | 353 | 949 | 248 | 90 | 338 | 220 | 36 | 256 | — | — | — | 1909 |
| No. infected | 46 | 15 | 61 | 178 | 132 | 310 | 99 | 56 | 155 | 70 | 10 | 80 | — | — | — | 606 | |
| Prevalence | 16.7 | 16.5 | 16.7 | 29.9 | 37.4 | 32.7 | 39.9 | 62.2 | 45.9 | 31.8 | 27.8 | 31.3 | — | — | — | 31.7 | |
| No. of samplesa | 10 (8) | 3 (3) | 13 (11) | 12 (11) | 11 (9) | 23 (20) | 9 (9) | 3 (3) | 12 (12) | 5 (5) | 0 | 5 (5) | — | — | — | 53 (48) | |
| Radix peregra | No. examined | — | — | — | — | — | — | — | — | — | 16 | 20 | 36 | 294 | 19 | 313 | 349 |
| No. infected | — | — | — | — | — | — | — | — | — | 12 | 7 | 19 | 7 | 1 | 8 | 27 | |
| Prevalence | — | — | — | — | — | — | — | — | — | 75.0 | 35.0 | 52.8 | 2.4 | 5.5 | 2.6 | 7.7 | |
| No. of samplesa | — | — | — | — | — | — | — | — | — | 1 (1) | 0 | 1 (1) | 4 (3) | 0 | 4 (3) | 5 (4) | |
| Lymnaea stagnalis | No. examined | 28 | 8 | 36 | 100 | 108 | 208 | — | 1 | 1 | — | — | — | — | — | — | 245 |
| No. infected | 5 | 2 | 7 | 12 | 21 | 33 | — | 0 | 0 | — | — | — | — | — | — | 40 | |
| Prevalence | 17.9 | 25.0b | 19.4 | 12.0 | 19.4 | 15.9 | — | 0 | 0 | — | — | — | — | — | — | 16.3 | |
| No. of samplesa | 0 | 0 | 0 | 2 (2) | 4 (4) | 6 (6) | — | 0 | 0 | — | — | — | — | — | — | 6 (6) | |
| Stagnicola palustris | No. examined | 29 | 6 | 35 | 530 | 85 | 615 | 15 | 3 | 18 | — | — | — | — | — | — | 668 |
| No. infected | 3 | 3 | 6 | 75 | 6 | 81 | 1 | 1 | 2 | — | — | — | — | — | — | 89 | |
| Prevalence | 10.3 | 50.0b | 17.1 | 14.5 | 7.1 | 13.2 | 6.7 | 33.3b | 11.1 | — | — | — | — | — | — | 13.3 | |
| No. of samplesa | 0 | 0 | 0 | 7 (6) | 2 (1) | 9 (7) | 0 | 0 | 0 | — | — | — | — | — | — | 9 (7) | |
| Planorbidae | |||||||||||||||||
| Gyraulus albus | No. examined | 5 | 14 | 19 | 2 | 26 | 28 | — | — | — | 1,098 | 830 | 1928 | 1 | 5 | 6 | 1981 |
| No. infected | 0 | 8 | 8 | 0 | 2 | 2 | — | — | — | 157 | 114 | 271 | 1 | 0 | 1 | 282 | |
| Prevalence | 0 | 57.1 | 42.1 | 0 | 7.7 | 7.1 | — | — | — | 14.3 | 13.7 | 14.1 | 100.0b | 0 | 16.7b | 14.2 | |
| No. of samplesa | 0 | 0 | 0 | 0 | 1 (0) | 1 (0) | — | — | — | 6 (6) | 5 (4) | 11 (10) | 0 | 0 | 0 | 12 (11) | |
| Segmentina nitida | No. examined | 15 | — | 15 | — | — | — | — | — | — | 127 | 53 | 180 | — | — | — | 195 |
| No. infected | 0 | — | 0 | — | — | — | — | — | — | 2 | 3 | 5 | — | — | — | 5 | |
| Prevalence | 0 | — | 0 | — | — | — | — | — | — | 1.6 | 5.7 | 2.8 | — | — | — | 2.6 | |
| No. of samplesa | 0 | — | 0 | — | — | — | — | — | — | 4 (1) | 1 (1) | 5 (2) | — | — | — | 5 (2) | |
aOnly samples consisting of n ≥ 14 snails were used in component community analyses; numbers in parentheses show samples with trematode infections. bSample size small (n < 14), excluded from component community analyses.