On abnormalities recorded in an urban population of Rhinella arenarum from central Argentina

Abstract

Urbanization is currently responsible for widespread declines of amphibian populations worldwide, through the loss and modification of aquatic habitat quality (Knutson et al., 1999; Riley et al., 2005; Hamer and Parris, 2011). Generally, aquatic systems in urban landscapes receive contaminants from different sources such as drainage of sewage, waste disposal, or agricultural runoff. It is well known that modification of natural habitat by humans negatively affects amphibian species at landscape level, and may result in local extinction of populations (McKinney, 2002; Löfvenhaft, Runborga and Sjögren-Gulveb, 2004). However, some amphibian species are relatively resilient to urbanization as a result of habitat generalism, or have specific life history traits that render them less vulnerable to habitat modification in urbanized areas (Rubbo and Kiesecker, 2005; Hamer and McDonnell, 2008; 2010). In this context, a considerable increase in research attention has been given to amphibian malformations related to anthropogenic activities, with emphasis on those related to agriculture and urbanization (Taylor et al., 2005; Piha, Pekkonen and Merilä, 2006; Lannoo, 2008; Peltzer et al., 2011). A low baseline rate of 0-5% of morphological abnormalities can be found in many amphibian populations, above this value, the abnormality frequency is considered high (Piha, Pekkonen and Merilä, 2006; Johnson and Bowerman, 2010).