Biodiversity and Conservation of Amphibians in the Okavango Delta

The aims of this project are to assess and document amphibian species diversity in the Okavango Delta and Linyanti regions of Botswana, evaluate possible threats to amphibians, and develop a conservation action plan to help manage threatened species in the area. 

Researcher: Marleen Le Roux

Background
The uniqueness of the Okavango ecosystem is well known and well documented. However, despite the fact that Northern Botswana has the distinction of being known as an amphibian hotspot, the amphibians of this area are in fact relatively poorly known.

In addition, a primary conservation issue of recent times is the global decline in amphibian populations - both because the causes of the decline are unclear and because amphibians frequently have complex life histories and occupy multiple niches, so that the loss of species can have wide-ranging consequences.

Project Details
The project aims to conduct a species diversity study of two regions in Northern Botswana. This will entail a detailed population and habitat survey which will provide baseline data for amphibian species currently present in the region. Intense field sampling sessions of five days per month for the duration of the rainy season will be undertaken in both the Xigera and Linyanti concessions where the majority of frogs will be caught by hand following chorus cues and tadpoles will be collected with dipnets. Terrestrial and leaf litter species will be collected with the aid of pitfall traps, while baited funnel traps will be used to collect aquatic species. Volunteers will be invited to participate in the collection. A photo database of each species per study area will be kept for future reference and a voucher collection of amphibians of Northern Botswana will be created. 

Species lists will be supplemented with detailed ecological data information on habitat preference, life histories and breeding behaviour through the use of GPS coordinates and observational notes at the capture sites.  

Recent research has uncovered a fungal pathogen of amphibians (Batrachochytrium dendrobatidis, or amphibian chytrid) that is apparently responsible for numerous amphibian declines and extinctions worldwide, indicating that global declines may have a common proximate cause. Compelling evidence to date suggests that the geographic source of amphibian chytrid is Southern Africa and that the spread of the disease has been greatly facilitated by the global trade in amphibians. The prevalence of the amphibian chytrid fungus among the various amphibian species in the region will therefore be assessed and its threat status determined. Frogs collected will be checked for symptoms associated with the disease and swabbed; the swabs will be sent to the National Zoological Gardens of South Africa (NZG) in Pretoria for detection of chytrid fungus through real time PCR. Tadpoles will also be screened for chytrid fungal infection.

Data from the Global Amphibian Assessment, Southern African Frog Atlas and Red Data Book and any other recent literature will be compiled to determine any perceived threats to amphibians of the region. The impacts of each threat will be evaluated and a priority list of threats in need of mitigation will be compiled.

The final objective is to create public awareness of amphibians in the region by increasing knowledge about amphibians as well as the importance of their conservation to local stakeholders via publications, talks and interactive tools.

This study is a timely one, undertaken to ensure that the unique amphibian diversity of the Okavango ecosystem be managed in such a way that future generations will still be able to enjoy and appreciate this system with its unique biodiversity.