Freshwater turtle biodiversity is exceptionally high in the Amazon basin; however, population-level studies remain scarce across much of the region. Important advances can come from research on populations inhabiting urban waterbodies. Freshwater turtles are notably adaptable and can persist even in highly disturbed environments, such as those found in cities.

A study recently published in Acta Herpetologica investigated the detectability and abundance of Phrynops geoffroanus and Mesoclemmys vanderhaegei in urban populations in Campo Grande (Mato Grosso do Sul, midwestern Brazil).

Four urban freshwater bodies were monitored between 2014 and 2017. Researchers identified, sexed, measured, and marked 94 turtles belonging to three species: two native (Phrynops geoffroanus and Mesoclemmys vanderhaegei) and one introduced (Trachemys dorbigni). Monthly precipitation and temperature data were obtained from the Brazilian National Institute of Meteorology to assess the influence of climatic conditions.

Detection probability varied among species and was strongly influenced by climate. In particular, detection probability of P. geoffroanus was clearly associated with environmental temperature, whereas both temperature and precipitation influenced detectability of M. vanderhaegei.

Phrynops geoffroanus was more abundant overall and more easily detected during the rainy season (November–March). In contrast, M. vanderhaegei showed a peak in abundance in December and remained relatively rare throughout the rest of the year. A broader pattern of syntopy emerged: each species tended to be more abundant in ponds where the other species was less common. This variation in habitat use may reflect differences in behavior, resource use, or morphology between the two turtles.

Overall, the study indicates that P. geoffroanus is the dominant species in these urban systems, likely due to its greater ecological adaptability. Although the introduced Trachemys dorbigni was recorded at low abundance, its presence warrants management attention, particularly given the potential impact on the less abundant and potentially more vulnerable M. vanderhaegei.

Read the full paper to learn more

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