Barcelona.- An international research team has managed to hear the boto (Inia geoffrensis) or pink dolphin of river and tucuxi (Sotalia fluviatilis), two species of endangered freshwater dolphins that inhabit inaccessible parts of the Amazon.
These species are threatened by human activity derived from fishing, agriculture, mining and the construction of dams, as reported this Friday by the Polytechnic University of Catalonia (UPC) in a statement.
Tracking these dolphins by listening to their emissions echolocation, which is the sound emitted by certain animals such as cetaceans, can be used to observe the movements of the two species of freshwater dolphins in the Amazon and thus carry out conservation strategies for their natural habitats, the note indicates.
The study, carried out by scientists from the Bioacoustic Applications Laboratory of the UPC, the Institutto de Desenvolvimento Sustentável Mamirauá and the National Marine Mammal Foundation, from San Diego (United States), has been carried out in some 800 square kilometers of the Reserve of Sustainable Development of Mamirauá, in Brazil.
To do this, they have used the data obtained through five submerged hydrophones at depths of between three and five meters in the Solimoes and Japurá rivers.
The results of the study, which have been published in the journal Scientific Reports (Nature), reveal new insights into the movements of river dolphinswhich could contribute to improve the conservation of these species.
The scientists have analyzed bioacoustic data from the reserve’s river channels, bays, lakes and flooded forests, at different periods during the wet and dry seasons, between June 2019 and September 2020.
Thus, they have detected that the presence of dolphins increased from 10% to 70% in the bay and in the river, as the water levels increased between the months of November and January.
The authors of the study believe that the dolphins used these waterways to enter the floodplain of this Amazon basin and that young botos and females with their cubs spent more time there than males, either because of the rich abundance of food or to be protected from the aggressive behavior of the males.
The researchers used deep learning algorithms, known as the Convolutional Neural Network, and manually collected bioacoustic data to automatically classify echolocation sounds from dolphins, sounds from boats, and also from rain, with some accuracy levels of 95%, 92% and 98%, respectively, as stated in the note.
They also urge the use of the methodology used to better understand and protect the habitat needs of Amazon river dolphins, within the framework of the Providence project, in which exhaustive bioacoustic monitoring of aquatic and terrestrial biodiversity is carried out in one of the forests. most endangered tropics on the planet.
