What Works in Conservation 2021
| , , ,1. Amphibian conservation
1.8 Threat: Invasive and other problematic species
Texte intégral
1.8.1 Reduce predation by other species
Beneficial
Remove or control fish by drying out ponds
1One before-and-after study in the USA found that draining ponds to eliminate fish increased numbers of amphibian species. Four studies, including one review, in Estonia, the UK and USA found that pond drying to eliminate fish, along with other management activities, increased amphibian abundance, numbers of species and breeding success. Assessment: beneficial (eflectiveness 80 %; certainty 66 %; harms 3 %).
http://www.conservationevidence.com/actions/826
Likely to be beneficial
Remove or control fish population by catching
2Four of six studies, including two replicated, controlled studies, in Sweden, the USA and UK found that removing fish by catching them increased amphibian abundance, survival and recruitment. Two found no significant effect on newt populations or toad breeding success. Assessment: likely to be beneficial (eflectiveness 50 %; certainty 52 %; harms 0 %).
http://www.conservationevidence.com/actions/827
Remove or control invasive bullfrogs
3Two studies, including one replicated, before-and-after study, in the USA and Mexico found that removing American bullfrogs increased the size and range of frog populations. One replicated, before-and-after study in the USA found that following bullfrog removal, frogs were found out in the open more. Assessment: likely to be beneficial (eflectiveness 79 %; certainty 60 %; harms 0 %).
http://www.conservationevidence.com/actions/825
Remove or control invasive viperine snake
4One before-and-after study in Mallorca found that numbers of Mallorcan midwife toad larvae increased after intensive, but not less intensive, removal of viperine snakes. Assessment: likely to be beneficial (eflectiveness 50 %; certainty 40 %; harms 0 %).
http://www.conservationevidence.com/actions/830
Remove or control mammals
5One controlled study in New Zealand found that controlling rats had no significant effect on numbers of Hochstetter’s frog. Two studies, one of which was controlled, in New Zealand found that predator-proof enclosures enabled or increased survival of frog species. Assessment: likely to be beneficial (eflectiveness 50 %; certainty 40 %; harms 0 %).
http://www.conservationevidence.com/actions/839
Trade-off between benefit and harms
Remove or control fish using Rotenone
6Three studies, including one replicated study, in Sweden, the UK and USA found that eliminating fish using rotenone increased numbers of amphibians, amphibian species and recruitment. One review in Australia, the UK and USA found that fish control that included using rotenone increased breeding success. Two replicated studies in Pakistan and the UK found that rotenone use resulted in frog deaths and negative effects on newts. Assessment: trade-ofls between benefits and harms (eflectiveness 65 %; certainty 60 %; harms 52 %).
http://www.conservationevidence.com/actions/828
Unknown effectiveness (limited evidence)
Exclude fish with barriers
7One controlled study in Mexico found that excluding fish using a barrier increased weight gain of axolotls. Assessment: unknown eflectiveness — limited evidence (eflectiveness 30 %; certainty 20 %; harms 0 %).
http://www.conservationevidence.com/actions/829
No evidence found (no assessment)
8We have captured no evidence for the following interventions:
- Encourage aquatic plant growth as refuge against fish predation
- Remove or control non-native crayfish.
1.8.2 Reduce competition with other species
Unknown effectiveness (limited evidence)
Reduce competition from native amphibians
9One replicated, site comparison study in the UK found that common toad control did not increase natterjack toad populations. Assessment: unknown eflectiveness — limited evidence (eflectiveness 10 %; certainty 23 %; harms 0 %).
http://www.conservationevidence.com/actions/821
Remove or control invasive Cuban tree frogs
10One before-and-after study in the USA found that removal of invasive Cuban tree frogs increased numbers of native frogs. Assessment: unknown eflectiveness — limited evidence (eflectiveness 65 %; certainty 30 %; harms 0 %).
http://www.conservationevidence.com/actions/822
No evidence found (no assessment)
11We have captured no evidence for the following interventions:
12• Remove or control invasive cane toads.
1.8.3 Reduce adverse habitat alteration by other species
Likely to be beneficial
Control invasive plants
13One before-and-after study in the UK found that habitat and species management that included controlling swamp stonecrop, increased a population of natterjack toads. One replicated, controlled study in the USA found that more Oregon spotted frogs laid eggs in areas where invasive reed canarygrass was mown. Assessment: likely to be beneficial (eflectiveness 60 %; certainty 47 %; harms 0 %).
http://www.conservationevidence.com/actions/823
No evidence found (no assessment)
14We have captured no evidence for the following intervention:
15• Prevent heavy usage/exclude wildfowl from aquatic habitat.
1.8.4 Reduce parasitism and disease – chytridiomycosis
Likely to be beneficial
Use temperature treatment to reduce infection
16Four of five studies, including four replicated, controlled studies, in Australia, Switzerland and the USA found that increasing enclosure or water temperature to 30–37°C for over 16 hours cured amphibians of chytridiomycosis. One found that treatment did not cure frogs. Assessment: likely to be beneficial (eflectiveness 60 %; certainty 70 %; harms 10 %).
http://www.conservationevidence.com/actions/770
Trade-off between benefit and harms
Use antifungal treatment to reduce infection
17Twelve of 16 studies, including four randomized, replicated, controlled studies, in Europe, Australia, Tasmania, Japan and the USA found that antifungal treatment cured or increased survival of amphibians with chytridiomycosis. Four studies found that treatments did not cure chytridiomycosis, but did reduce infection levels or had mixed results. Six of the eight studies testing treatment with itraconazole found that it was effective at curing chytridiomycosis. One found that it reduced infection levels and one found mixed effects. Six studies found that specific fungicides caused death or other negative side effects in amphibians. Assessment: trade-ofls between benefits and harms (eflectiveness 71 %; certainty 70 %; harms 50 %).
http://www.conservationevidence.com/actions/882
Unknown effectiveness (limited evidence)
Add salt to ponds
18One study in Australia found that following addition of salt to a pond containing the chytrid fungus, a population of green and golden bell frogs remained free of chytridiomycosis for over six months. Assessment: unknown eflectiveness — limited evidence (eflectiveness 41 %; certainty 25 %; harms 50 %).
http://www.conservationevidence.com/actions/762
Immunize amphibians against infection
19One randomized, replicated, controlled study in the USA found that vaccinating mountain yellow-legged frogs with formalin-killed chytrid fungus did not significantly reduce chytridiomycosis infection rate or mortality. Assessment: unknown eflectiveness — limited evidence (eflectiveness 0 %; certainty 25 %; harms 0 %).
http://www.conservationevidence.com/actions/765
Remove the chytrid fungus from ponds
20One before-and-after study in Mallorca found that drying out a pond and treating resident midwife toads with fungicide reduced levels of infection but did not eradicate chytridiomycosis. Assessment: unknown eflectiveness — limited evidence (eflectiveness 25 %; certainty 25 %; harms 0 %).
http://www.conservationevidence.com/actions/766
Sterilize equipment when moving between amphibian sites
21We 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 eggs, tadpoles or hatchlings. However, one of the studies found that bleach significantly reduced tadpole survival. Assessment: unknown eflectiveness — limited evidence (eflectiveness 10 %; certainty 30 %; harms 40 %).
http://www.conservationevidence.com/actions/768
Treating amphibians in the wild or pre-release
22One before-and-after study in Mallorca found that treating wild toads with fungicide and drying out the pond reduced infection levels but did not eradicate chytridiomycosis. Assessment: unknown eflectiveness — limited evidence (eflectiveness 27 %; certainty 30 %; harms 0 %).
http://www.conservationevidence.com/actions/767
Use gloves to handle amphibians
23We found no evidence for the effects of using gloves on the spread of disease between amphibian populations or individuals. A review for Canada and the USA found that there were no adverse effects of handling 22 amphibian species using disposable gloves. However, three replicated studies in Australia and Austria found that deaths of tadpoles were caused by latex, vinyl and nitrile gloves for 60–100 % of species tested. Assessment: unknown eflectiveness — limited evidence (eflectiveness 9 %; certainty 35 %; harms 65 %).
http://www.conservationevidence.com/actions/769
Unlikely to be beneficial
Use antibacterial treatment to reduce infection
24Two studies, including one randomized, replicated, controlled study, in New Zealand and Australia found that treatment with chloramphenicol antibiotic, with other interventions in some cases, cured frogs of chytridiomycosis. One replicated, controlled study found that treatment with trimethoprim-sulfadiazine increased survival time but did not cure infected frogs. Assessment: unlikely to be beneficial (eflectiveness 38 %; certainty 45 %; harms 10 %).
http://www.conservationevidence.com/actions/763
Use antifungal skin bacteria or peptides to reduce infection
25Three of four randomized, replicated, controlled studies in the USA found that introducing antifungal bacteria to the skin of chytrid infected amphibians did not reduce infection rate or deaths. One found that it prevented infection and death. One randomized, replicated, controlled study in the USA found that adding antifungal skin bacteria to soil significantly reduced chytridiomycosis infection rate in salamanders. One randomized, replicated, controlled study in Switzerland found that treatment with antimicrobial skin peptides before or after infection with chytridiomycosis did not increase toad survival. Assessment: unlikely to be beneficial (eflectiveness 29 %; certainty 50 %; harms 10 %).
http://www.conservationevidence.com/actions/764
No evidence found (no assessment)
26We have captured no evidence for the following intervention:
- Use zooplankton to remove zoospores
1.8.5 Reduce parasitism and disease – ranaviruses
No evidence found (no assessment)
27We have captured no evidence for the following intervention:
28• Sterilize equipment to prevent ranaviruses.
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