Diversity, Distribution, and Habitat of Herpetofauna Around Gambella Zuria District, West Ethiopia

International Journal of Zoology and Applied Biosciences ISSN: 2455-9571 Volume 5, Issue 2, pp: 68-78, 2020 http://www.ijzab.com https://doi.org/10.5281/zenodo Research Article DIVERSITY, DISTRIBUTION, AND HABITAT OF HERPETOFAUNA AROUND GAMBELLA ZURIA DISTRICT, WEST ETHIOPIA Abeje Kassie1* and Afework Bekele2 1Animal Biodiversity Directorate, Ethiopian Biodiversity Institute, Addis Ababa, Ethiopia 2Department of Zoological Sciences, College of Natural Sciences, Addis Ababa University, Addis Ababa, Ethiopia Article History: Received 29th March 2020; Accepted 8th April 2020; Published 12th April 2020 ABSTRACT Herpetofauna is the least studied group of vertebrates in general in the world and in particular in Ethiopia. This study was carried out to describe the species composition, diversity, distribution and species richness of amphibians and reptiles in Gambella Zuria District, Gambella National Regional State, Western Ethiopia. The study was conducted in 2018. Pitfall traps along with drift fence and Visual encounter survey methods were used to capture the amphibians and reptiles for visual estimation. Herpetofauna was investigated in three habitat types such as wetland, agricultural land, and house and riverine forest. A total of 95 amphibian individuals categorized under nine species, belonging to six genera in six families were recorded. In addition to amphibians, a total number of 17 reptile species belonging to three orders, 11 different families, and 13 genera were recorded. Out of which, five species were snakes, 10 species of lizards, one species of Turtle and one species of Crocodile. Ptychadena nilotica was the most abundant amphibian species while Agama finchi was highest from reptile species in the study area. Tedia riverine forest (H=1.81; D=5.02) was the most amphibian species-rich and diverse among the four habitat types. Agricultural land and house had the lowest diversity index (H=0.64; D= 1.8) compared to other habitat types. Karmi riverine forest (H=2.03) was the most reptile species-rich and diverse among the four habitat types followed by Agricultural land and house (H=1.69). Jenena wetland had the lowest diversity index (H=1.09) compared to other habitat types. This study showed that Gambella Zuria District is rich in amphibian and reptile species. A further extended molecular study should be carried out to obtain detailed information on the abundance and population structure of herpetofauna for better understanding and develop conservation strategies in Gambella Zuria District riverine forests and wetland areas. Keywords: Amphibia, Reptile, Distribution, Diversity, Gambella, Herpetofauna. INTRODUCTION are notably abundant and species-rich in tropical areas where they play critical roles in food webs often linking Herpetofauna is a group of vertebrates that include terrestrial and aquatic ecosystems. Current distribution and amphibians and reptiles. Herpetofauna (herps) form an ecology of both amphibians and reptiles closely reflect important component of our ecosystem by linking rainfall and temperature patterns, which will have terrestrial with the aquatic ecosystem and the lower significant impacts on amphibian and reptilian biodiversity vertebrates with the higher vertebrates (Bickford et al., (Bickford et al., 2010). 2010). Due to their pokilothermic nature, they are more susceptible to seasonal variation than other vertebrates. Herpetofauna in Ethiopia has received little attention Seasonal changes affect three major physiological functions from the scientific community, which explains the of amphibia viz., water balance, thermo-regulation and significantly lower number of species reported for Ethiopia hormonal regulation of reproduction (Donnelly & Crump, compared to neighboring countries like Kenya. Currently, 1998). Although generally unseen or overlooked, 75 species of amphibians and 242 reptiles are recognized in ectothermic terrestrial vertebrates, amphibians, and reptiles Ethiopia (Abeje Kassie, unpublished data), although the are important components of ecosystems worldwide. They species list is not a definite one and a greater sampling *Corresponding Author: Abeje Kassie, Animal Biodiversity Directorate, Ethiopian Biodiversity Institute, Addis Ababa, Ethiopia, Email: [email protected], Mobile: +251 913205773 68 Abeje Kassie and Afework Bekele Int. J. Zool. Appl. Biosci., 5(2), 68-78, 2020 effort is still required for many regions. Although Ethiopia information obtained from the District Agricultural Office, has a wide diversity of ecosystems that may harbor a great the total population of the Gambella Zuria District is diversity of species, many ecosystems remain unexplored. 14,599 (male 7,591, female 7,008). The annual temperature At the same time, most areas are facing a sustained loss of of the District ranges from 27oC to 40oC, with an elevation habitat and degradation through forest fragmentation, an in the range of 450 to 1,000 meters above sea level. The increase of the agricultural frontier, and pollution. average annual rainfall ranges from 1,000 mm to 2,000 Gambella region is a poorly explored area that is facing mm, and Baro is the main river. The area is lowland and it anthropogenic pressures like deforestation, agricultural has many rivers and riverine forests. The area also harbors investment, and other habitat fragmentation. Although large areas of wetlands. The study area is stratified into forest loss has occurred in the area, there are still reserves three habitats from three Kebeles (Figure1). These are that could potentially serve as refugia for several Tidia Riverine Forest (found in Abol Kebele), Karmi organisms. This is of great importance especially for Riverine Forest (found in Karmi Kebele) and Jenina amphibians and reptiles, which are facing population wetland (found in the Gambella town Kebele 04). declines worldwide. Therefore, the aim of this study is to analyze the herpetofauna species composition found at the Sampling Design Gambella Zuria District. The study area was stratified into three habitats: riverine forest, wetlands/swamps, and agricultural land. Six MATERIALS AND METHODS sampling sites (two sites for each habitat) were purposively chosen and established in selected study habitats for data Study site collection. The study area was Gambella Zuria District, part of the Data Collection Methods Anuak Zone, Gambella National Regional State. It is bounded by Abobo in the south, Itang in the west, and Data collection methods followed the standard methods Oromia Region in the north and east. The administrative proposed by Heyer et al., (2014) and (Howell, 2002). The center of the District is Abol. The total surface area methods included drift fence pitfall trap, active search, and coverage of the District is 2,586 km2. According to the visual survey. Figure 1. Map of the study area. 69 Abeje Kassie and Afework Bekele Int. J. Zool. Appl. Biosci., 5(2), 68-78, 2020 Drift Fence and Pitfall Trap traps. Each transect line had ten buckets sunk into the ground with the rim level of the ground at 5 m interval (Howell, 2002)was employed using a drift fence and pitfall along the drift fence. Three transect lines with drift and trap (Figure 2) with 10 liters of the bucket (Howell, 2002) pitfall traps were constructed in eight data collection sites. to collect amphibian and reptile species. The drift fence The distance between the transect line was determined by consisted of plastic sheeting, 60 cm in height and 55 m in the suitability of the area to herpetofauna. The drift fence length. This was constructed to intercept and redirect and pitfall traps were checked twice a day early in the amphibians and reptiles moving on the ground into pitfall morning and late evening before sunset. Figure 2. Sketch of the Drift Fence and Pitfall Trap Layout (Davies et al., 2002; Howell, 2004). Active Searching and Visual Encounter Survey Largen and Spawls, 2010; Spawls et al., 2018). After taking records, caught individuals were released 50 m away An active search was undertaken randomly in sites away from the capture area to avoid recapture (Pickersgill et al., from the transect lines involving turning over logs, leaf 2017). Nonetheless, individuals that could not be identified litter, tree holes, rocks, and other potential hideout at the data collection sites were collected as voucher searching areas for amphibians and reptiles. Active search specimens and preserved in 97% ethanol. The voucher and visual surveys were undertaken day and night. Each specimens were deposited at EBI Zoology Museum for site was searched in a group during the time interval permanent preservation. between 6:00 and 7:00 a.m. for day time and 7:00 to 8:00 p.m. for night time. We had collected data for each Data Analysis individual of a species encountered during fieldwork. The locality, date, time, weather condition, habitat, Data collected from the field through traps and an active microhabitat, the gender of each individual (when possible) search was used for statistical analysis of amphibians and was recorded in a field datasheet. We had also taken reptiles. taxonomic note of individuals captured during the fieldwork and morphometric data of the individual Species Diversity gathered. Geographic coordinates for each survey site was Shannon – Wiener Index of Diversity, (H′) was used to determined in the field with a Garmin GPS 72 receiver. calculate diversity of species in various habitats Coordinates were recorded as latitude and longitude in decimal degrees. During day time, we searched for

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