The Impact of Location on Diet and Morphological Features of Frog (Hoplobatrachus occipitalis) in Ogun State, Nigeria O.A. Akintunde*; A.L.A. Shotuyo; T.M. Obuotor; and L.A. Ayodele Federal University of Agriculture, Abeokuta, Nigeria. E-mail: [email protected]* ABSTRACT Across the collection site, mean distribution values for H. occipitalis ranged from 4.00±0.1 to Amphibians are a very diverse group of 9.00±0.2. Morphometric parameters (cm) were vertebrates, they inhabit varied habitat with most better with H. occipitalis in Yewa North when species living within terrestrial, fossorial, arboreal compared with other locations There were or freshwater ecosystem. This study investigated significant (p<0.05) difference in the distribution, the impact of location on diet and morphological abundance and morphometric parameters of the features of amphibians especially frog species at the study sites. Feeding habit of H. (Hoplobatrachus occipitalis). occipitalis in the study area across locations showed 17 food items made up of 6 taxa; Four amphibians each were collected from Coleoptera, Plecoptera, Hemiptera, Hospital Area, Mechanic Village, Quarry Site and Ephemeroptera, Crustacean and Anura, Residential Area across four Local Government Percentage occurrences of isolated bacteria Areas in Ogun State. Morphometric features such were: Escherichia coli (38.46%), Salmonella sp. as Head Length (HL), Head Width (HW), Snout- (30.76%), Pseudomonas sp. (15.38%), Proteus Tympanum Length (STL), Mouth Angle-Snout sp. (7.69%), Bacillus sp. (7.69%). The study Length (MSL), Nostril-Snout Length (NSL), Mouth concluded that location influences the Gap (MG), Trunk Length (TL), Snout Vent Length distribution, abundance morphometric (SVL) Hind Limb Length (HLL), and Body Weight parameters of amphibians most especially frogs (BW) were determined using digital Vernier in the study area. Good environmental calipers. management practices, conservation education and domestication efforts were part of suggested Stomach contents of each sample were viewed recommendations. under stereoscopic microscope. A guide to various foods of amphibians was used to identify (Keywords: amphibian, frog, abundance, location, diet, each of the diets. Diet compositions were habitat, morphometry, habitat ecology). determined using percentage frequency of occurrence and numerical percentage of diet components. Total aerobic bacterial count (TABC) INTRODUCTION of the gut contents were determined using standard microbiological methods. Food and Habitat ecology is a way of studying relationships feeding habit were subjected to ecological between organisms and their environment that diversity indices such as Margalet index, Shannon involves characterizing and explaining statistical and Weiner index, and Pielou index. patterns of abundance, distribution and diversity. In other words, it is the study of the mechanisms Data obtained were analyzed using descriptive behind the distribution of species and the statistics, linear regression equation, Pearson’s relationship between species and their correlation co-efficient, and Analysis of Variance. environment on a large scale (Brown and Maurer Three species of amphibians from 3 families were 1989; Brown 1995). identified in the study area namely, Bufo bufo (75.0%), Hoplobatrachus occipitalis (18.9%), and Amphibians are a very diverse group of Xenopus laevis (6.1%). Mean distribution values vertebrates; however, in general their feeding is for Hoplobatrachus occipitalis ranged from opportunistic with food up to gape width being 2.00±0.2 to 9.00±0.1 across the study location. ingested. Amphibians such as frogs and toads The Pacific Journal of Science and Technology –346– http://www.akamaiuniversity.us/PJST.htm Volume 21. Number 2. November 2020 (Fall) only target moving prey and prefer elongated prey especially damaging to the skin, eyes, and eggs such as crickets or insect larvae that move across of amphibians), and diseases like their field of vision. However, many aquatic chytridiomycosis. However, many of the causes amphibians will target food by scent and will of amphibian declines are still poorly understood, consume inert food. The suitability and range of (Waddle, 2006; Hloch, 2010). live feeds are assessed in the Amphibian Population Management Guidelines (Schad, Currently, there are no established diet and 2007). morphological methods for most species of amphibians (especially frogs) and scanty Anurans are the largest group of amphibians. information is available about ecology and Approximately 5,200 species are in this group physiology of many of them in Nigeria especially (Frost 2006), and they reside on all of the major in the South- Western part of the country. Based continents except Antarctica and on many oceanic on these and other ecological relevancies islands (Pough, et al. 2004; Zug, et al. 2001). engendered this research with a view to assess Compared with other tetrapods, anurans have impacts of location on abundance, distribution, short trunks (only 5-9 presacral vertebrae), broad, morphological features and diets of amphibians flat heads with extensive reduction of bone, and especially frog (Hoplobatrachus occipitalis) in hind limbs that are substantially longer than the Ogun State, Nigeria forelimbs in most species. With a few exceptions, adult amphibians are predators, feeding on virtually anything that moves that they can METHODOLOGY swallow. Their diet mostly consists of small preys that do not move too fast such as beetles, Study Area caterpillars, earthworms, and spiders. The sirens (Siren spp.) often ingest aquatic plant material Ogun State was created in 1976 from the former with the invertebrates on which they feed Western State. The State is located in the South (Gabbard, 2000). Amphibians usually swallow Western part of Nigeria. It covers a total of food whole but may chew it lightly first to subdue 1,640,076 square kilometers of land mass where it. They typically have small hinged pedicellate over 60 percent are cultivable arable land, with teeth, a feature unique to amphibians. an estimated population of about 3.391 million. According to the International Union for the The State is heterogeneous comprising the Egba, Conservation of Nature (IUCN), amphibians may Yewa, Egun, Awori, and Ijebu ethnic groups who be the only major group currently at risk globally. speak different languages. The study area lies IUCN assesses the status of species on a global within Latitudes 6 41'N - 7 9'N and Longitudes 3 scale and maintains a database of species that 16'E - 3 41'E covering an aerial extent of about face a high risk of global extinction: the IUCN Red 915 km (Figure 1). The area has elevation List of Threatened Species. The IUCN Red List, ranging from 40 m in the South to 154 m in the recent detailed worldwide assessment and North (Salami and Olorunfemi, 2014). Ogun State subsequent updates show that nearly one-third of occurs within the humid tropical rain forest region species (32.4%) are either globally extinct or of Nigeria characterized by two climatic seasons: threatened with extinction (Critically Endangered, the rainy season of about eight months (March to Endangered and Vulnerable), representing 2,030 October) and the dry season of about four species (IUCN, 2011). months (November to February). Populations of many species of frogs have declined dramatically in relatively undisturbed Amphibian Collection habitats at high altitudes and anthropized areas throughout the world (Blaustein and Wake, 1990, Samples were collected at different locations (i.e. 1995; Collins and Storfer 2003; Pounds, et al., Hospital areas, Mechanic villages, Quarry sites 2006; Reading, 2007). A number of causes are and Residential areas) and within the following believed to be involved, including habitat Local Government Areas (Abeokuta North, destruction and modification, over-exploitation, Abeokuta South, Yewa North and Ijebu North) of pollution, introduced species, climate change, Ogun State. Different species of amphibian were endocrine disrupting pollutants, destruction of the targeted using dip net method. ozone layer (ultraviolet radiation has shown to be The Pacific Journal of Science and Technology –347– http://www.akamaiuniversity.us/PJST.htm Volume 21. Number 2. November 2020 (Fall) Figure 1: Map of Ogun State Showing the Study Area. Four samples were collected from each sampling Diet Composition site making a total of 64 samples in 16 sampling sites for morphometric assessment. The contents of each stomach were preserved in a labelling specimen bottle containing the morphological information using 10% formalin. Morphometric Assessment Drops of the samples were placed on slide and viewed under stereoscopic microscope at X40 Morphometric characters such as Head Length magnifying lens. A guide to various foods of (HL), Head Width (HW), Snout-Tympanum Length amphibians were used in identifying each of the (STL), Mouth Angle-Snout Length (MSL), Nostril- diets seen through the microscope. Analyses Snout Length (NSL), Mouth Gap (MG), Trunk were carried out using frequency of occurrence Length (TL), Snout Vent Length (SVL) Hind Limb and numerical methods as described by Hyslop "Length (HLL), and Body Weight (BW) were (1980). determined according to (Islam, et al., 2008). Percentage frequency of occurrence is given as: Head lengths were measure from back of mandible to tip of snout. Head widths were taken Ni 100% from left side back of mandible to right side back Fi = (1) of mandible. Snout-tympanum lengths