Work

First record of biogenic silica in the stomach contents of South American freshwater turtles

Year: 2026

Type: article

Abstract: Sponges of the phylum Porifera, especially those in the class Demospongiae, produce siliceous spicules, while plants form phytoliths, both of which are sources of biogenic silica in aquatic environments. Marine and freshwater turtles have diets that vary throughout their life stages and may consume these organisms. However, there are still few studies investigating the ingestion of biogenic silica by freshwater turtles. This study aimed to analyze the diversity of biogenic silica bodies in the stomachs of Phrynops geoffroanus. Specimens were captured in Iguaçu National Park (PNI), Paraná, a vital remnant of the Atlantic Forest. Individuals underwent biometric measurements, photographic documentation, and euthanasia using Thiopental (93 mg/kg), following strict ethical protocols. Biological material was sent to the State University of Maringá, where stomachs were extracted. Stomach contents were processed at the Laboratory of Paleoenvironmental Studies (LEPAFE) at the State University of Paraná (UNESPAR), treated with HNO₃ on a heating plate, and the resulting material was mounted on slides for analysis. Three specimens of Phrynops geoffroanus at different ontogenetic stages were examined. Stomach analysis revealed the presence of biogenic silica, including phytoliths, diatom frustules, and sponge spicules, with the highest concentration found in young individuals and the lowest in juveniles. The predominant phytolith types suggest interactions with grasses and Podostemaceae. Gemmuloscleres of Oncosclera navicella were identified in young and adult individuals, confirming predation on freshwater sponges. This study highlights the interaction between Phrynops geoffroanus and organisms that produce biogenic silica.

Source: Acta Herpetologica

DOI: 10.36253/a_h-18063

Authors: Luan Maler de Oliveira, Mauro Parolin, Carlos Eduardo Vargas Grou, Matheus Maximilian Ratz Scoarize, Evanilde Benedito

Institutions: Universidade Estadual de Maringá, Universidade Estadual do Paraná

Language: English

Topic: Turtle Biology and Conservation

Subfield: Nature and Landscape Conservation

Field: Environmental Science

Domain: Physical Sciences

SDG: Life below water

Open Access status: diamond

Funders: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Instituto Chico Mendes de Conservação da Biodiversidade