Browsing by Autor "Mariana Paschoalini Frias"

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Bolivian River Dolphin trends: A long-term analysis in the Mamore basin
(Public Library of Science, 2024) Luis A. Guizada Duran; Enzo Aliaga‐Rossel; Mariana Paschoalini Frias; Alexandre N. Zerbini
South American river dolphins face significant threats from intense human activities, resulting in habitat loss, fragmentation of their natural connectivity, overfishing, pollution, and incidental and intentional catches for use as bait for fisheries. From 1998 to 2022, 12 surveys were conducted in a river system in the Mamore River (Ibare-Tijamuchi-Mamore) basin, one of the primary distribution areas of the Bolivian river dolphin (BRD - Inia geoffrensis boliviensis). Generalized linear models (GLMs) were used to assess population trends. The most supported model does not definitively indicate a decline in population. The estimated mean annual rate of population change for BRDs over the 24-year monitoring period was -0.0115 per year. The average count of BRDs in the Ibare River is lower (mean = 20, n = 4) compared to the mean of Tijamuchi (mean = 260, n = 4), and the same pattern is observed with the Mamore River (mean = 76, n = 4). There is tentative visual evidence of negative trend for the count of BRD based on the GLM curves, but the statistics are still inconclusive to the sub-basin of the Mamore River. This study highlights the importance of continue with monitoring efforts on river dolphin populations. Similar population dynamics are observed in other river dolphin species in the Amazon region, requiring immediate actions to reduce mortality and reverse the concerning decreasing trend exhibited by these populations.
Breaking down silos: Conservation areas for Amazonian flagship terrestrial and freshwater species
(Society for Conservation Biology, 2025) Natalie Shahbol; Melissa Arias; Valeria Boron; Helga Correa Wiederhecker; Bernardo Caldas; Fabiola La Rosa; Robin Naidoo; M Oliveira-da-Costa; Jessica Pacheco; Mariana Paschoalini Frias
Abstract Research into the threats affecting flagship terrestrial and freshwater species in the Amazon has operated within disciplinary and ecological silos, neglecting the interconnectedness between these species and ecosystems. In this study, we aimed to bridge these divides by identifying Amazon areas harboring high jaguar densities and high richness of migratory freshwater species, highlighting the potential co‐benefits of integrated terrestrial and freshwater conservation approaches. We also assessed the risks posed to these areas by habitat and connectivity loss due to impending dam construction, deforestation, and the lack of coverage by area‐based conservation schemes. We found that 17% of the Amazon River Basin is covered by areas of high jaguar density and freshwater migratory species richness, 83% of which are found in Brazil and Peru. A third of these areas are located outside of formal protected areas or Indigenous territories, with Bolivia representing the largest gap in formal protection. The proposed construction of 54 hydroelectric dams and the expansion of deforestation poses an immediate threat to the habitats and connectivity of these areas. Given the risk of an Amazon ecological tipping point, our study underscores the need for integrated terrestrial and freshwater conservation approaches that set in motion international collaboration to secure transboundary flagship and umbrella species.
What do we know about the population trend of the Bolivian River Dolphin: A Population Analysis with long-term data
(Research Square (United States), 2023) Luis Alfredo Guizada-Duran; Enzo Aliaga‐Rossel; Mariana Paschoalini Frias; Alexandre N. Zerbini
Abstract South American river dolphins face significant threats from intense human activities, resulting in habitat loss, fragmentation of their natural connectivity, overfishing, pollution, and incidental and intentional catches (e.g., for use as bait for fisheries). From 1998 to 2022, twelve surveys were conducted in a river system in the Mamore River (Ibare-Tijamuchi-Mamore) basin, one of the primary distribution areas of the Bolivian river dolphin (BRD - Inia geoffrensis boliviensis ). Generalized linear models (GLMs) were used to assess population trends. The most supported model does not definitively indicate a decline in population. The estimated mean annual rate of population change for BRDs over the 24-year monitoring period was − 0.0115 per year. The mean count of BRDs in the Ibare River is approximately 21.2% of the mean count in Tijamuchi, while in the Mamore River, it is 41.1%. However, there is still no evident decline in the populations in the sub-basin of the Mamore River. This study highlights the importance of still monitoring river dolphin populations. Similar population dynamics are observed in other river dolphin species in the Amazon region, necessitating immediate actions to mitigate or reduce mortality and reverse the concerning trend exhibited by these populations.