Anthropic influence on chelonian composition in a metropolitan region of Southern Brazil

Abstract

Knowledge about chelonians in Brazil remains limited, especially concerning basic research on these organisms. Considered one of the most threatened vertebrate group, chelonians are negatively affected by different factors such as anthropic pressure.  Therefore, this study had two main goals: to describe the freshwater turtle assemblage within the urban and periurban area of Maringá and Sarandi, Southern Brazil, as well as to compare turtle composition between areas accessed by people and inaccessible areas. Fieldwork was conducted in six sites in 2013, 2014, 2016, 2017 and 2021, employing four different methods to record turtles. A total of five species were registered, whith two native to the region (Hydromedusa tectifera, Phrynops geoffroanus) and three exotic taxa (Trachemys dorbigni, Trachemys scripta elegans, Platemys platycephala platycephala). The most abundant species was T. dorbigni (n=162), followed by P. geoffroanus (n=140) and T. scripta elegans (n=95). To analyze the anthropic influence on the turtle composition, standardized samplings were conducted in two accessed and two inaccessible areas and Principal Coordinate Analysis (PCoA) was performed. The results revealed a strong relationship between the human presence in the areas and the occurrence of exotic turtles. The two alien taxa (T. dorbigni and T. scripta elegans) represented 74.5% of all chelonians analyzed, indicating a worrying scenario for the urban ecosystem.