Some of these pollutants might cause changes in the physiology and morphology of affected animals, such as a reduction in metabolism or an increasing risk of malformations, leading to a reduced larval survival. Indeed, numerous studies have demonstrated the negative effects of roadside pollutants (e.g., heavy metals, salts) on amphibians, particularly during larval development. This has led to the suggestion that SWPs might act as ecological traps for such species. Despite their primary role to retain road pollutants, some species, especially amphibians, breed inside SWPs, at least in North America and Western Europe. The name “stormwater” pond refers to the design of these water reservoirs to collect all water, even in case of maximum rainfall, i.e., during a storm. These stormwater ponds (SWPs) are used to collect, store, and clean up runoff water from the roads before it is released into the environment. To mitigate the impact of such chemical pollution, roadside stormwater ponds have been constructed.

Besides the devastating consequences associated with the destruction and fragmentation of the landscape, road traffic further impacts biodiversity through the emission of pollution (e.g., chemical, light, and noise) The chemical pollution (e.g., hydrocarbons and heavy metals), washed off the road surface by rain, originates from tires, fuel residues, and the asphalt used to pave roads. From 1957 to 2012, the European road network alone increased from 146.7 million to 421.8 million kilometers. Hence, we suggest that adequate management measures are needed to limit leech penetration inside SWPs (frequent dredging/draining) to prevent these artificial structures from becoming an ecological trap for locally endangered amphibians but rather a base to help in their recovery.ĭuring the last century, the world has witnessed the construction of an enormous road network. Our study found that leeches had the strongest effect on tadpole survival and were likely responsible for the low survival rates in SWPs observed recently. Tadpoles swim speed and metabolic rate of toadlets did not differ between the ‘ control’ and ‘ SWP sediment’ group, the only conditions with surviving individuals. By contrast, leeches heavily preyed upon tadpoles, leaving no survivors in conditions 2 and 4. We found that the growth rate of tadpoles exposed to the SWP sediment (condition 3) was increased, while pollution had no effect on survival. Tadpole size and survival was monitored until metamorphosis and, individuals participated in swim tests and respirometry trials to the test potential effects of pollution on their escape capacity and metabolic rate. We tested the following conditions: (1) ‘ control’ (clean sediment + clean water) (2) ‘ leech’ (clean sediment + clean water + leeches) (3) ‘ SWP sediment’ (clean water + polluted sediment) and (4) ‘ SWP sediment + leech’ (clean water + polluted sediment + leeches). To establish the effects of sediment pollution and leech presence on tadpole growth and survival, we exposed 480 green toad tadpoles to a number of controlled conditions inside holding tanks. Recently, a study found a very low survival rate of European green toad tadpoles ( Bufotes viridis) inside SWPs, presumably because of high sediment pollution and/or the presence of a leech Helobdella stagnalis. However, the suitability of such artificial ponds as a breeding habitat for amphibians remains unclear. Declining wetland areas cause many amphibian species to breed inside stormwater ponds (SWPs), which have been constructed alongside major roads to collect and retain polluted road runoff water.

Pocket tanks free trial