Abundance and Population Structure of Hydromedusa tectifera Cope 1869 in a Highly Anthropogenic Environment in Argentina

Abstract

The present study characterizes a population of Hydromedusa tectifera in a humandisturbed stream in Buenos Aires province, Argentina. We analyzed the variation of abundance, sex ratio, body condition index, and size class distribution across 3 sections of the Rodriguez stream with different degrees of urbanization regarding house density (null, low, and high) along the stream margins. Fieldwork was carried out from March 2017 to January 2018. Turtles were caught manually, and the following variables were recorded: site, transect and margin, sex, straight carapace length, and weight. We found 109 H. tectifera individuals (56 males, 46 females, and 7 hatchlings) with a balanced sex ratio and body condition index that did not vary among sites. Most turtles were caught at the site with greatest urbanization degree. However, our results showed no significant differences in the number of turtles caught among stream sites. Regarding size class distributions, the population consists largely of medium-sized to large adult turtles (150– 250 mm). The present study demonstrates that the moderate urbanization degree occurring along the Rodriguez stream seems not to have negative impact on the studied population of H. tectifera. Some of the topics highlighted here constitute a first step to understanding how urbanization impacts this species. In any case, we suggest that a periodic monitoring program of the studied population is necessary in order to monitor the studied parameters and include new ones, such as habitat requirements, reproduction sites, and food quality, among others, that would probably be useful for population management to achieve better integration between the city and the turtles living there.