Up to 58,000 animal species die every year. The reasons are diverse: they lose their habitat, die from diseases or toxic pesticides, are displaced by immigrant species or suffer from climate change to name just a few. A Swiss research group led by ecologist Helen Moor from the Federal Research Institute for Forest, Snow and Landscape (WSL) and the Water Research Institute Eawag has shown in a study in cooperation with the coordination center for amphibian and reptile protection in Switzerland that at least endangered amphibians Can use new pools for the animals in which they can reproduce. On the one hand, the number of descendants increases, on the other hand, the populations are better networked thanks to the larger pond density in the landscape. The group published its results in the specialist magazine »PNAS«.
"Even if the negative reports on the loss of biodiversity can be overwhelming, our study shows that it is worthwhile to implement conservation measures and that populations can recover," says Helen Moor, according to a WSL statement. The data for the study come from the canton of Aargau. More than 400 new ponds and ponds have been created here within 20 years. The amphibians colonized the new waters, the populations of ten of the twelve endangered species – including the common midwife toad (Alytes obstetricans), the yellow-bellied toad (Bombina variegata) and the northern crested newt (Triturus cristatus) – increased until 2019. The population of the European tree frog (Hyla arborea) even "exploded". We were amazed at the clear result," says Moor, "especially in view of the fact that the other threats have not diminished in the meantime."
Since 1999, the amphibian stocks in the canton of Aargau have been monitored with a monitoring program along the five major river valleys. For the most part, volunteers collect the data. The researchers of the WSL enter them into a complex statistical model that, on the one hand, compensates for the errors that arise during observation, and, on the other hand, predicts the change in the occupation of the ponds. It turned out that the larger a newly created pond was, the higher the chance that it would be populated. The proximity to the forest and other ponds were also criteria that encouraged settlement.
In 77 percent of the 43 known metapopulations, newly created ponds were able to stabilize the species (14 percent) or even increase the number of individuals (63 percent). However, one species has so far not benefited from the conservation measures: the croune (Epidalea Calamita). It prefers very large, temporarily flooded surfaces in the open country with a fluctuating water level. "The species has specific demands on their habitat, which must be taken into account accordingly during pond construction," says Moor. So far, this has apparently not yet been achieved in the canton of Aargau.
The scientists around Helen Moor now hope that this method will meet with interest and application worldwide, as the construction of ponds is "simple and effective". Moor: "Sooner or later, every newly created pond will be valuable for amphibians."
