Science Snippets: Where Frogs Flourish

Comparing frogs and habitats in KwaZulu Natal

Cherise Acker, EWT’s Threatened Amphibian Programme,

Wetlands are important ecosystems that supply essential ecological goods and services (EGS) for wildlife and people. They supply clean water and fertile soil for plants, filter water from upstream, regulate water flow to prevent flooding, store water to ease drought periods, and reduce the effects of climate change, improving ecological and social resilience. Protection and conservation of wetlands are essential to support communities through environmental disasters caused by climate change.

Wetland health and ecological goods and service quality assessments are valuable in determining the ecological state of wetlands to inform conservation management actions. The Endangered Wildlife Trust’s (EWT) Threatened Amphibian Programme (TAP) aims to show the link between amphibian diversity (i.e. healthy amphibian populations) and wetland habitat health. In other words, if wetlands are in a poor ecological state, amphibian diversity decreases and vice versa. Indirectly, better species and ecological health also support healthy human populations. To this end, we started long-term monitoring protocols in 2016 to determine habitat health and identify amphibian species diversity at four project sites in eThekwini Municipality, KwaZulu-Natal, where the threatened Pickersgill’s Reed Frog (Hyperolius pickersgilli) occurs.

These sites included Adams Mission, Mt Moreland’s Froggy Pond, Widenham, and Isipingo. Wetland health scores, EGS scores, and amphibian diversity from each site were compared to determine whether amphibian species richness increases or decreases under different habitat conditions.

Diagram illustrating the correlation between amphibian species diversity and wetland health

Figure 1: Diagram illustrating the correlation between amphibian species diversity and wetland health.

The data showed a significant positive relationship between the amphibian species diversity and Wetland Health assessment scores between the four sites (P-Value 0.04077) (Social Statistics, 2022), as illustrated in Figure 1.

Species composition for each site showed that some species were found across all sites (Figure 2). These included Hyperolius tuberlinguis, Hyperolius marmoratus, Leptopelis natalensis (Figure 3), and Hyperolius pickersgilli was also present at all four sites, but Hyperolius pickersgilli was one of the site selection criteria and as such, expected to be present at all the sites.

Figure 2: Species present according to the number of sites, i.e. Hyperolius tuberilenguis occurs in all four sites while Natalobatractus bonebergi, only occurs in one site.

Figure 4: Hyperolius tuberlinguis (top left), Hyperolius pickersgilli (top right), Leptopelis natalensis (bottom left) Hyperolius marmoratus (bottom right)

The study’s results indicate a statistically significant positive relationship between these two variables, demonstrating that amphibian species diversity will decrease as wetland health decreases and vice versa. Reinforcing the value of amphibian species diversity in indicating wetland health. Amphibians may be an effective monitoring tool for managing wetlands within the eThekwini Municipality. Furthermore, the study demonstrates that improving habitat health through restoration or rehabilitation could positively impact amphibian species diversity.