Biology Prof & Student Take Research Trip to the Amazon

Marajó Island is the largest fluvial island on Earth, about the size of Switzerland, spanning over 15,000 square miles. It is located in the Brazilian State of Pará at the mouth of the Amazon River and is well-known for its rich archeological history as it was once home to an advanced pre-Columbian society, the Marajoara culture. Because of this, the island has been the focus of scientific exploration since the 19^th century. However, little attention has been placed on Marajó’s diverse wildlife.

Abreu and Longoria setting traps in the Amazon Forest with landowner Dozé Azevedo The goal of the Marajó Island expedition was to fill some of that biodiversity knowledge gap. Along with colleagues from Cal Poly Humboldt, Dr. Silvia Pavan and Dr. Pedro Peloso, Abreu is working on a National Science Foundation-funded project to investigate the diversity, origin and evolution of small mammals (rodents and opossums), reptiles (lizards and snakes) and amphibians (frogs, toads and salamanders) inhabiting Marajó.

Longoria, a natural resource management major from Houston, joined Abreu and the Cal Poly scientists on a research team that also included faculty and students from three Brazilian universities. They collected and documented numerous animal species near the town of Anajás in the center of Marajó Island, including 12 species of small mammals, six marsupials and six rodents.

Abreu with a native Brazilian rodent, Neacomys marajoara - Photo by Pedro Peloso “The fieldwork was a success with over 50 specimens collected, which will now have their DNA sequenced for comparative genetic analysis,” Abreu said. “Some of the small mammals we collected were documented for the first time at Marajó, and their correct identification will require detailed genetic and morphological investigation.”

Members of the Amazon research team at Jairo Figueiredo's property - Photo by Pedro Peloso The field survey took place primarily on two private lands owned by local families. Some people living on the island still maintain a simple ancestral lifestyle, making their living from small crops of native plants, such as cassava, and from forest products, such as the açaí palm. These humble people welcomed the scientists into their homes and provided crucial assistance during the fieldwork. Jairo Figueiredo and Dozé Azevedo, who own the properties surveyed by the scientists, helped them with setting up and checking traps, as well as during nocturnal hunting.

“Getting to know these extraordinary people and learning from their inherited knowledge of the forest is something that makes me want to return to Amazonia again and again,” Abreu said.

“Throughout this expedition,” Longoria said, “my energies were equally divided between fieldwork and being constantly awestruck by the whole experience. Picking up some Portuguese, trying out new food, and hacking down saplings during an Amazonian downpour were half the fun. While in the deep night tracking down mammals in a small canoe, I looked up to see the sky dappled with foreign stars, a reminder to me that Mother Nature need not convince us of her mystery.”

This was Abreu’s second research trip to the Amazon in less than a year. In 2024, he and ASU biology student Aramide Oladiran spent a month in Brazil as part of a 14-person research team, seeking out rare and new mammal species in remote sites along the Purus River in the Amazon Forest. During that trip, the researchers collected and documented over 300 specimens representing about 65 different species.