Action: Artificially mist habitat to keep it damp
- One before-and-after study in Tanzania found that installing a sprinkler system to mitigate against a 90% reduction of river flow did not maintain a population of Kihansi spray toads.
Reduction in river flow due to activities such as the implementation of hydropower projects can have significant effects on wetland habitats and the amphibians they support. In cases where alternative habitat is not available, intensive management may be undertaken to recreate natural habitats in attempt to conserve particular species. For example, the wetland habitat in the study described below was the only known habitat for the Kihansi spray toad Nectophrynoides asperginis.
Supporting evidence from individual studies
A before-and-after study in 1996–2004 of a sprinkler system to mitigate against a 90% reduction of river flow caused by a hydropower project along the Lower Kihansi River, Tanzania (Krajick 2006, Conservation Breeding Specialist Group IUCN/SSC 2007) found that following a brief recovery, the Kihansi spray toad Nectophrynoides asperginis declined rapidly. Following the implementation of the sprinkler system, numbers increased to approximately 20,000 by June 2003 from 11,000 in 2000. However, the population then declined rapidly to 40 in August 2003 and five in January 2004. Authors suggest that causes for the sudden decline may have been introduction of the chytrid fungus or pesticides. The population estimate for the toads had decreased from 50,000 in 1996 to 11,000 toads in 2000 once the river flow was reduced. The hydropower project was implemented in May 2000 resulting in a reduction of water flow, but the sprinkler system was not completed until February 2001. The system comprised a several kilometre-long gravity-fed pipe system that delivered mist from hundreds of spray nozzles onto a quarter of the suitable toad habitat.