The Abundance of D. muelleri, E. ovalis, P. albonatatus

1. The Abundance of D. muelleri, E. ovalis, P. albonatatus and P. fuscomaculata in Comparison to Rainfall in the Southern Pantanal (2005-2006) Hannah Doerrier1, Vanda Lucia Ferreira2, and Janet Buckner1 1State University of New York at Oswego, Federal University of Mato Grosso du Sul2 Introduction Objectives Methods For our research we used the database from nine different expeditions to Fazenda Nhumirim (18º59´00”S/56º39´00” W) in Mato Grosso do Sul, Brazil, from February 2005 to May 2006. The collections were carried out using pitfall traps, which are very common in collecting small animals, including insects and amphibians. The buckets were approximately 100 liters and installed in environments of forest, field (native and Brachiaria), Savannah, both in areas with and without the presence of cattle The database was organized by species abundance and age group (adults, sub-adults and youth) using the rostro-anal length (snout-cloaca) (CRA) that varied by species (Table 1) -To use a database of previously collected/identified reptiles and amphibians from pitfall traps located in the southern Pantanal at Fazenda Nuhmirim in Mato Grosso do Sul, Brazil in order to visualize species abundance by age group. -Look at the abundance patterns of four different Anurans species, D. muelleri (Figure 1), E.ovalis (Figure 2), P. albonatatus (Figure 3) and P. fuscomaculata. -Finally we wanted to compare the abundance by sex to the amount of rainfall experienced in the area of collection (data courtesy of Embrapa Pantanal). The Pantanal is one of the most ecologically diverse places on the earth and the largest flood plain on the planet with an area of 140,000 km^2 (Uetanaboro et al. 2008). Due to its distinct seasons of wet and dry periods it makes the Pantanal a great place to study amphibian ecology. Frogs are highly dependent on water for reproduction and they have adapted different strategies in using these periods of wet/dry (Duellman & Trueb 1994) The abundance of species was compared with the database of rainfall from October 2004 to May 2006 from Embrapa-Pantanal.This was used to find a pattern of abundance of species by age and the volume of rain that preceeded the period of collection. The species were grouped by biological reproduction associated with rain. D. Muelleri and E.ovalis are fossorial and require a greater volume of rain to start the reproductive activity. P.albonatatus and P.fuscomaculatus do not need much rain as they are cryptozoic. Using the data compiled about daily rainfall and abundance of juvenilles we looked for the period that probably led to the laying of eggs of these individuals. Physalaemus albonatatus and pleurodema fuscomaculata (Leiuperidae) have prolonged reproduction pattern and build foam nests as a shelter for egg development (Prado, Uetanabaro, Haddad 2005). Dermatonotus muelleri and Elachistocleis ovalis (Microhylidae) have explosive reproduction patterns and tend to be opportunists, reproducing during/directly after periods of heay rain. They do this by laying eggs in or on top of ponds (Prado, Uetanabaro, Haddad 2005). All these species have development in the larval stage and the period of metamorphosis is still unknown for the natural environment. Figure 1 Dermatonotas muelleri photograph courtesy of 2003 Micro Sole Table 1 Figure 2 Elachistocleis ovalis Photograph courtesy of 2006 Sebastian Lotzkat Figure 3 Physalameus albonatatus Photo courtesy of Wikipedia.com Results Conclusions All four species of frogs are showing a direct realtionship to the amount of rainfall at Fazenda Nhumirim. Generally, during/directly after months of consistent rainfall there was an increase in the abundance of frogs in these áreas. During the months of March 2005 to September 2005 there was little to no rainfall (Figure 4) and in turn little to no frogs found during this period for any of the species (Figures 5-8). For all species more juvenilles were captured than adults (Figures 5-8). D.muelleri is a terrestrial/fossorial frog, which helps to explain why in Figure 5 little to no adults were collected (Uetanaboro et al 2005).Their juvenille abundance pattern seems most similar to that of E.ovalis, both showing the most amount of juveniles in February 2005 after a long period of substantial rainfall from October 2004 to February 2005 (Figures 4,5,6). E.ovalis had more adults visible throughout the collection (Figure 6). P. albonatatus and P. fuscomaculata both showed similiar patterns of abundance. January 2006 was when the most amount of adults were present for both species (Figures 7 and 8). P. albonatatus may have a shorter metomorphosis time, as the most juveniles were seen in March 2006 (Figure 7). P. fuscomaculata showed the most juveniles in May 2006, which is four months after the most adults (Figure 8). Our graphs are showing a strong correlation between the amount of rainfall and the amount of frogs captured. These species are dependent on this water and thrive when excess rainfall accures. In order to strenghten this study it would be beneficial to make collections every month of the year and compare each months abundance to the amount of rainfall. Figure 5 is showing few adults except for Oct ‘05 and the most amount of juveniles (615) in Feb ‘05. Figure 6 is showing the most amount of adult and juveniles were collected during Feb ‘05 (244/490) and Mar ‘06 (280/345). It is also showing a period between June ’05- Oct ‘05 were little/no frogs were found Figure 4 is showing the daily rainfall experienced at the farm in which this collection took place. The data was provided by Embrapa. There seems to be a large amount of rainfall experienced from Oct ’04- Feb’05 with 19 days with >20mm of rain. Between Mar ‘05- Sept ‘05 there is little rainfall experienced and less than 5 days with substantial rainfall (>20mm). From Oct ’05-May ‘06 there is almost daily rainfall, with many days of substantial rain. Figure 8 is showing the largest amount of adults collected in Jan ‘06 (358) and juveniles in Mar ‘06. Fig. 5 is showing the most adults in Jan ’06 (268) and the most juveniles in May ‘06 (658). Figure 7 is showing the most amount of adult and juveniles were collected during Feb ‘05 (244/490) and Mar ‘06 (280/345). It is also showing a period between June ’05- Oct ‘05 were little/no frogs were found. References Duellman, W., Trueb, L. (1994): Biology of Amphibians . Baltimore, The Johns Hopkins University Press. Prado, C.P.A, Haddad, C.F.B. 2005. Size-fecundity relationships and reproductive investment in female frogs in the pantanal, south-western Brazil. Herpetological Journal 15: 181-189. Prado, C.P.A., Uetanabaro, M., Haddad, C.F.B. (2005): Breeding activity patterns, reproductive modes, and habitat use by anurans(Amphibia) in a seasonal environment in the Pantanal, Brazil. Amphibia-Reptilia 26: 211-221. Thome, M.T.C, Brasileiro, C.A. 2007. Dimorfismo sexual, uuso do ambiente e abundancia sazonal de Elachistocleis cf. ovalis (Anura: Microhylidae) em um remanescente de Cerrado no estado de Sao Paulo, sudeste do Brasil. Biota Neotropica 7: 27-33. Uetanabaro, M., Prado, C.P.A., Rodrigues, D.J., Gordo, M., Campos, Z. (2008): Field Guide to the Anurans of the Pantanal and Surrounding Cerrados. UFMS and UFMT. Acknowledgements Vanda L. Ferreira, PhD.Janet Buckner