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Keywords = Sotalia fluviatilis

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17 pages, 1467 KiB  
Article
Density and Abundance Estimation of Amazonian River Dolphins: Understanding Population Size Variability
by Mariana Paschoalini, Fernando Trujillo, Miriam Marmontel, Federico Mosquera-Guerra, Renan Lopes Paitach, Heloise Pavanato Julião, Gabriel Melo Alves dos Santos, Paul André Van Damme, André Giovanni de Almeida Coelho, Mariana Escobar Wilson White and Alexandre Novaes Zerbini
J. Mar. Sci. Eng. 2021, 9(11), 1184; https://doi.org/10.3390/jmse9111184 - 27 Oct 2021
Cited by 9 | Viewed by 4361
Abstract
The dolphins Inia geoffrensis—boto and Sotalia fluviatilis—tucuxi are threatened cetaceans inhabiting river ecosystems in South America; population numbers are still lacking for many areas. This paper provides density and abundance estimations of boto and tucuxi in 15 rivers sampled during the [...] Read more.
The dolphins Inia geoffrensis—boto and Sotalia fluviatilis—tucuxi are threatened cetaceans inhabiting river ecosystems in South America; population numbers are still lacking for many areas. This paper provides density and abundance estimations of boto and tucuxi in 15 rivers sampled during the past nine years as part of a multinational research alliance. Visual boat-survey data collection protocols and analyses have been developed since 2012 (based on Distance Sampling methods) and recently reviewed (2019) to improve robustness and comparability. Differences across the sampled rivers and the analyzed river basins (Amazon and Orinoco) pointed to a density/population size gradient with lower densities and abundances observed in the Orinoco basin (0.9–1.5 ind./km²), passing through the eastern Amazon basin (2–5 ind./km²), and the largest numbers found at the central Brazilian Amazon (lower Purus River—2012 (14.5 boto/km², N = 7672; 17.1 tucuxi/km², N = 9238)). However, in other parts of the central Amazon, the density of dolphins was smaller than expected for high productive whitewater rivers (1–1.7 ind./km² in the Japurá and Solimões rivers). We attributed these differences to specific features of the basin (e.g., hydro-geomorphology) as well as to the cumulative effects of anthropogenic activities. Full article
(This article belongs to the Special Issue Cetaceans Ecology: Diversity, Abundance and Distribution)
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21 pages, 940 KiB  
Article
Molecular Identification and Historic Demography of the Marine Tucuxi (Sotalia guianensis) at the Amazon River’s Mouth by Means of Mitochondrial Control Region Gene Sequences and Implications for Conservation
by Manuel Ruiz-García, David Mejia, Pablo Escobar-Armel, Daniela Tejada-Martínez and Joseph Mark Shostell
Diversity 2013, 5(4), 703-723; https://doi.org/10.3390/d5040703 - 25 Sep 2013
Cited by 2 | Viewed by 8415
Abstract
In 2005, three fishermen, with artisan fishing vessels and drift gillnets, accidentally captured around 200 dolphins between Vigia and Salinópolis in the Amazon River estuary. The dolphins died and they then prepared their vaginas and penises in order to sell them in the [...] Read more.
In 2005, three fishermen, with artisan fishing vessels and drift gillnets, accidentally captured around 200 dolphins between Vigia and Salinópolis in the Amazon River estuary. The dolphins died and they then prepared their vaginas and penises in order to sell them in the Ver-ao-Peso market in the city of Belem within the Brazilian state of Pará. We randomly sampled a minimal quantity of tissue of these sexual organs from 78 of these 200 dolphins and we determined the following results after sequencing 689 base pairs (bp) from the mitochondrial control region gene: (1) 96.15% (75/78) of these dolphins belonged to the species Sotalia guianensis. The other species detected were Steno brenadensis, Stenella coeruleoalba and Tursiops truncatus; (2) The levels of gene diversity found in this sample of S. guianensis were high (33 haplotypes, haplotype diversity of 0.917 and nucleotide diversity of 0.0045) compared to gene diversities found in other Brazilian S. guianensis locations; (3) All the population genetics methods employed indicated a clear population expansion in this population. This population expansion could have begun 400,000 years ago; (4) The haplotype divergence within this population could have begun around 2.1 millions of years ago (MYA), with posterior splits around 2.0–1.8 MYA, 1.7–1.8 MYA, 1–1.5 MYA, 0.6–0.8 MYA, 0.4–0.2 MYA and 0.16–0.02 MYA, all during the Pleistocene. Full article
(This article belongs to the Special Issue Molecular Systematic and Genetic Diversity)
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