Population structure and reproductive allometry of Podocnemis expansa (Testudines, Podocnemididae) around the Parque Nacional do Araguaia, Tocantins

Author(s)

Thiago Costa Gonçalves Portelinha

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2010-05-14

Examining board members

Jaime Aparecido Bertoluci; Adriana Malvasio; Carlos Ignacio Piña

• Advisor: Jaime Aparecido Bertoluci

Abstract

Among the reptiles found in the Amazon, the turtles stand out because of its diversity and economic importance. Podocnemis expansa, popularly known as Amazon river turtle, is considered the largest freshwater turtle in South America and has been heavily exploited for centuries by many indigenous and riverine communities. This study aimed to expand the knowledge about the population ecology and the reproductive biology of P. expansa in the Javaés River, Tocantins State, around the Parque Nacional do Araguaia (Iha do Bananal). In the first chapter of this dissertation some aspects of population ecology were investigated. Fieldwork was carried out between 2004 and 2009, and the animals were captured by diving and trawling net. The age structure (based on carapace length) of the animals showed a unimodal pattern for males and not a standard defined for females. The population consisted mainly of young females and adult males, with a sex ratio of 1:1.4 (:), biased to females. The relative abundance varied between 0.4 and 8.6 animals per hour depending on the method of capture employed, and most animals (73.7%) was concentrated in a single specific point of the river. In the second chapter, the allometric relationships between female body size, their tracks, the clutch variables and nest form in natural environment were investigated. Fieldwork was carried out on a nest beach of the study area, between September and December 2008. Results indicated that P. expansa female body size can be estimated based on her track. Larger females leave larger foot tracks in the sand and produce more eggs (clutch size) with greater mass (clutch mass) than smaller females. Female carapace width and female body mass can be regarded as reliable to establish relationships in studies of allometry with P. expansa. (AU)

• FAPESP's process: 07/05040-0 - Population ecology of Podocnemis expansa (Testudines, Podocnemididae) in the Parque Nacional do Araguaia, river Javaés, Tocantins.
• Grantee: Thiago Costa Gonçalves Portelinha
• Support Opportunities: Scholarships in Brazil - Master