2023-07-27 14:55:56
He vote (Inia geoffrensis) or pink river dolphin and the tucuxi (Sotalia fluviatilis) are two species of endangered freshwater dolphins that inhabit inaccessible parts of the Amazonas. These species are threatened by human activity derived from the fishingthe agriculturethe mining and the construction of dams.
During the wettest period of the year, between the months of April and August, both species of dolphins move to the rivers of the areas of rain forests of the Amazon (floodplains) in search of freshwater fish. However, the floodplain and vegetation make it extremely difficult to observe dolphins with boats or drones.
The researchers have used data obtained from five submerged hydrophones at depths of between three and five meters in the Solimões and Japurá rivers.
the researcher Florence Erbs and other scientists from Bioacoustic Applications Laboratory from the Polytechnic University of Catalonia (UPC) have studied some 800 square kilometers from reserva of sustainable development of Mamiraua, in Brazil. For this, they have used the data obtained through five hydrophones submerged in depths between three and five meters in the Solimões and Japurá rivers.
The results of the study, which have been published this week in the journal Scientific Reportsreveal new knowledge about the movements of river dolphins, which could contribute to improve the conservation of these species. The work has been carried out together with scientists from the Instituto de Desarrollo Sustentável Mamirauá (IDSM) and the National Marine Mammal Foundation, in San Diego, USA.
A specimen in the Mamirauá sustainable development reserve (Amazon)./ Marina Gaona , IDSM.
In the article are analyzed bioacoustic data from the fluvial channels, bays, lakes and flooded forests of this reserve. These were recorded in different periods, during the wet and dry seasons, between June 2019 and September 2020.
Young botos and females with pups of these dolphin species spent more time in the floodplains than males.
The experts used deep learning algorithms—what is known as Convolutional Neural Network o red neuronal convolucional— and manually collected bioacoustic data to automatically classify echolocation sounds from dolphins, ship noises and also from rain, with accuracy levels of 95%, 92% and 98%, respectively.
Thus, they detected that the presence of dolphins increased from 10% to 70% in the bay and the river, as the the water levels rose, between November and January.
Another behavior that the researchers highlight is that the dolphins were using these waterways to enter the floodplain of this Amazon basin. Young botos and females with pups of these dolphin species spent more time in the floodplains than males, either because of the rich abundance of prey or as a safeguard against aggressive behavior of males.
The study authors encourage other scientists to use the methodology they have employed to better understand y protect preferences and habitat needs of the Amazon river dolphins. In particular, they recommend these techniques to be used within the framework of the project Providencewhich carries out exhaustive bioacoustic monitoring of aquatic and terrestrial biodiversity in one of the most threatened tropical forests on the planet.
Reference:
André, M. et al. “Towards automated long-term acoustic monitoring of endangered river dolphins: a case study in the Brazilian Amazon floodplains”. Scientific Reports (2023)
Rights: Creative Commons.
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