Researchers embark on expedition in search of electric fish in Amazon

Their goal is to identify new species and preserve biodiversity

Published on 25/02/2024 - 15:00 By Camila Boehm - Agência Brasil - São Paulo

A group of researchers began an expedition this week to search the depths of the Negro River, in the state of Amazonas, in streams and other environments in the region for species belonging to the Gymnotiformes order, known as electric fish. Besides identifying new species, the researchers intend to contribute to raising awareness and preserving local biodiversity.

The expedition is part of the Diversity and Evolution of Gymnotiformes project, coordinated by Naercio Menezes, a professor at the Zoology Museum of the University of São Paulo (MZ-USP), which has been running since 2017. Over the years, one of the results was the discovery and description, in 2019, of two species of Electrophorus electricus, known in the Amazon as poraquê.

"In one of our collections, one of our researchers discovered two new species, one of which produces 650 volts through its electric organ, enough to knock a person over, so to speak. This discovery caused quite a stir," said Menezes, who reported that it was published in the New York Times.

He points out that the Zoology Museum is highly representative of freshwater fish from all over Brazil and part of South America. He also emphasizes that the work is aimed at preservation, stating, “Our intention is to showcase the existing diversity and highlight the threat posed by the disappearance of species due to the construction of hydroelectric power stations, fires, mining, and deforestation.”

One of the species the researchers will be searching for is Iracema caiana, which was collected only once in 1968 in the region of the expedition. They will also be looking for other species that could contribute to ongoing studies or even lead to the description of new species. The expedition, which is expected to last until March 2, will involve around 20 people on the boat, including crew and researchers, who will travel upriver from Manaus to Santa Isabel do Rio Negro.

Expedição para pesquisa busca espécies de peixes-elétricos na Amazônia. Foto: Acervo dos Pesquisadores
One of notable results of the expedition was the discovery and description of two species of poraquê in 2019 - Researches archive

Amazon drought

Menezes stated that the expedition's favorable conditions, including the use of a net that drags along the riverbed and a large team of researchers, make the possibility of collecting specimens very high. This is further enhanced by the specific period in which the expedition will take place.

"We're aiming to collect at an opportune time. Last year's significant drought in the Amazon basin led to increased turbidity in the waters of the Negro and Branco, our collection sites. We hope that this circumstance concentrated the fish in specific areas," he explained.

The researchers will also employ molecular studies, where tissue samples undergo DNA analysis. This method allows for more precise species identification and aids in morphological and anatomical research.

Menezes explains that electric fish use the electricity they produce for feeding and communication. The Diversity and Evolution of Gymnotiformes project also revealed that one species, the poraquês, engages in social predation, where prey is captured in groups.

"In the past, it was believed that they fed in isolation. However, they have the ability to surround the minnows (piabinhas)—small freshwater fish—and emit continuous shocks. The species then jumps out of the water and the poraquês consume their prey. This behavior was previously unknown," he explained.

Translation: Mário Nunes -  Edition: Nádia Franco

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