Table 1.
Main characteristics of the 14 watercress beds studied in 2016–2018 in northern Haute Vienne, with indication of the number of Fasciola hepatica metacercariae.
| Type of watercress bed | Length of the macrophyte-free zone (m) | Number of beds | Length of the bed in m (area in m2) | Flow speed (cm/s)* | Number of cysts over 3 years |
|
|---|---|---|---|---|---|---|
| Total | Means (SD) | |||||
| With a slow-flow spring | 0.13–0.24 | 3 | 6.6–9.2 (2.9–4.1) | 0.5–1.7 | 89 | 29.6 (17.3) |
| 1.1–1.8 | 2 | 6.3–7.9 (2.8–3.5) | 0.9–2.1 | 81 | 40.5 (27.5) | |
| 3.1–3.5 | 2 | 7.8–9.5 (3.5–4.2) | 0.7–1.6 | 50 | 25.0 (12.5) | |
| With a faster-flow spring | 0.15–0.29 | 2 | 6.4–6.9 (2.8–3.1) | 5.2–6.7 | 93 | 46.5 (15.2) |
| 1.3–1.6 | 2 | 8.1–11.2 (3.6–5.0) | 4.3–7.2 | 51 | 25.5 (8.4) | |
| 3.0–3.2 | 3 | 9.3–12.2 (4.1–5.4) | 5.4–8.2 | 4 | 1.3 (0.4) | |
*
Two records per year and per furrow over a three-year period. The records were collected in early April with a 3-day interval between 10 a.m. and 11 a.m.