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Providing evidence to improve practice

Action: Sterilize equipment when moving between amphibian sites Amphibian Conservation

Key messages

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  • We found no evidence for the effects of sterilizing equipment when moving between amphibian sites on the spread of disease between amphibian populations or individuals.
  • Two randomized, replicated, controlled study in Switzerland and Sweden found that Virkon S disinfectant did not affect survival, mass or behaviour of common frog or common toad tadpoles or moor frog embryos or hatchlings. One of the studies found that bleach significantly reduced survival of common frog and common toad tadpoles.


Supporting evidence from individual studies


A randomized, replicated, controlled study in 30 artificial pools in Switzerland (Schmidt et al. 2009) found that Virkon S disinfectant did not affect survival, mass or behaviour of common frog Rana temporaria and common toad Bufo bufo tadpoles, but bleach did. Survival did not differ between Virkon treatments for frogs (untreated: 70–100%; low dose: 90–100%; high dose: 40–100%) or toads (untreated: 90–100%; low dose: 100%; high dose: 70–100%). All tadpoles died within 1–2 days in high dose bleach. Survival was significantly lower in low dose bleach than untreated water for frogs (20–100 vs 70–100%) and toads (40–100 vs 90–100%). Frog tadpole mass was significantly higher in low dose bleach (0.5–0.6 g) than other treatments (0.3–0.5 g). Toad tadpole mass did not differ (0.2–0.4 g). The proportion of tadpoles feeding did not differ significantly for frogs (0.4–0.9) or toads (0.6–0.9). Local leaves, phytoplankton, zooplankton and a snail were added to artificial pools (80 L). Disinfectants (bleach 2%; Virkon 10 g/L) that would be used for boots and field equipment were applied to pools once a week at high (0.04 L) or low doses (0.004 L), with 0.060 L or 0.096 L of water respectively. Water was added as the control. Treatments were replicated five times and assigned randomly to tubs. Ten frog and toad tadpoles were added to each treatment.



A randomized, replicated, controlled study in 2011 of captive moor frogs Rana arvalis at Uppsala University, Sweden (Hangartner & Laurila 2012) found that Virkon S disinfectant had no significant effects on moor frog embryos and hatchlings, but did reduce hatching success. Embryonic survival was significantly lower in the low (92%), but not high concentration of Virkon S (94%) compared to the control (99%). Abnormalities were infrequent in all treatments (low: 3%; high: 4%; control: 1%). Hatchling body length did not differ between treatments (5 mm). However, hatching success was lower with Virkon S compared to without, suggesting that it may have weak negative effects on amphibian embryos. Embryos and hatchlings were reared at 19°C in high (5 mg/L) and low (0.5 mg/L) Virkon S concentrations and in a control of water. One embryo and six hatchlings from each of six clutches were used per treatment. Survival was recorded daily until the free swimming stage and hatchling length for seven days.


Referenced papers

Please cite as:

Smith, R.K., Meredith, H. & Sutherland, W.J. (2019) Amphibian Conservation. Pages 9-65 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2019. Open Book Publishers, Cambridge, UK.