Bioacoustic assessment of anuran diversity in the Rugeramigozi wetland of Muhanga district, Rwanda

Abstract

Anuran (frogs and toads) are currently being studied for their ecological significance and spatial distribution influenced by both environmental changes and biotic processes. Anthropogenic alteration of ecological systems such as wetlands may be indicated by the presence or absence of anuran species as this group are considered biological indicators for wetland quality. In Rwanda, anuran diversity changes from one wetland to another and the use of this information in the management of wetlands are still inadequate. The present study informs about the diversity of the anuran community in Rugeramigozi wetland, a cultivated wetland of Rwanda. I estimated the abundance and richness of anuran species in the wetland and determined the variation in the calling activity of anuran species. Eight distinct microhabitats types were chosen for sampling in the Rugeramigozi wetland to assess the diversity of anuran species using eight bioacoustic night surveys coupled with visual detection. Sampling occurred on one night in October, three in November and four in December 2018. Results indicate a total of 13 anuran species Hyperolius viridiflavus, H. rwandae, H. kivuensis, Afrixalus quadrivittatus, Kassina senegalensis, Amietia nutti, Sclerophrys regularis, Ptychadena anchietae, P. nilotica, P. porosissima, Phrynobatrachus natalensis, Phrynobatrachus kakamikro and Xenopus victorianus detected in the wetland. Identified species presented significant variation in their calling patterns, dependent on the time of day and type of microhabitats. The detected anuran species are good representatives of an altered wetland following heavy human disturbance which confirms the current status of Rugeramigozi wetland in Muhanga district. The local α–diversity index presented a high species diversity at microhabitats with high vegetation and high water available and low diversity at microhabitats with poor or shallow vegetation despite presence of water. The β- Diversity index showed a high similarity of anuran species among microhabitats with similar characteristics. The presence of Ptychadena spp (P. anchietae, P. porosissima and P. nilotica) indicates a heavy disturbance of the Rugeramigozi wetland as Ptychadena ssp are distributed in wetlands with high human disturbances. Our study results show that the surveyed anurans are representative of heavily altered wetlands.