A new approach to monitoring tadpoles of the Table Mountain Ghost Frog
A BETTER METHOD TO MONITOR THE CRITICALLY ENDANGERED TABLE MOUNTAIN GHOST FROG WILL LINK TADPOLE ABUNDANCE TO HABITAT REQUIREMENTS
The Table Mountain ghost frog is listed as Critically Endangered by the IUCN Red List because of its small and restricted natural range (less than 9 km²) and perceived threats from habitat modification, which includes habitat loss through construction of dams, water abstraction, alien vegetation and high visitor numbers to the Table Mountain National Park (Photo: Josh Weeber).
The Table Mountain ghost frog (Heleophryne rosei) is elusive. It hides in rock crevices just millimetres wide. If you search the streams of Table Mountain, you are likely to only find tadpoles of this critically endangered amphibian. CapeNature monitored H. rosei from 2003 to 2020 by conducting 30-minute tadpole searches at seven sites on six streams during autumn’s low flows. Tadpole presence and results may indicate fluctuations in recruitment from year to year. However, no environmental parameters were measured at the time of the counts, and the exact date for each autumn count is unknown. Therefore, fluctuations in this annually repeated count could not be attributed to variation in environmental parameters, such as stream flow, water quality and the presence of alien species.
Development of a monitoring methodology that links tadpole presence to habitat health to better understand
environmental drivers of tadpole numbers, and thus ghost frog population health, is important. Thus, in 2019/2020, the Endangered Wildlife Trust employed PhD candidate Josh Webber to develop and publish a method to measure the relationship between tadpole detectability and habitat health, using the Index of Habitat Integrity of Kleynhans.
The index quantifies in-stream and riverbank habitat quality and includes evaluation of stream flow, water quality, bank erosion, presence of exotic aquatic fauna and macrophytes. SANParks participated in fieldwork in the autumn of 2022/23, further testing the new method which incorporates environmental variables, to help gauge the importance of these for tadpole abundance.
Tadpole of the critically endangered Table Mountain ghost frog, a new method will link tadpole abundance with tadpole habitat and climate requirements (Josh Weeber).
Adult Table Mountain ghost frogs are hard to count as they hide in very small crevices and other small spaces, therefore tadpoles are typically used as an indicator of population health (Photo: Jeremy Shelton).
This article was originally published in the 2022/2023 Research Report.
