River dolphins are strongly affected by the construction of hydroelectric dams. Potential isolation in subpopulations above and below such dams and the resulting low genetic variability of these subpopulations can cause extinction at a local level. Here we aimed to estimate density and population size of South American river dolphins (boto Inia geoffrensis and tucuxi Sotalia fluviatilis), map their distribution, and estimate potential biological removal (PBR) limits in order to evaluate the effects of population fragmentation between planned dams in the Tapajós River, Amazonian basin, Brazil. Boat-based surveys were conducted following a line transect sampling protocol covering different dolphin habitats in 2 stretches of the river divided by rapids. The mark−recapture distance sampling method was applied to account for animals missed on the trackline. After the estimation of population sizes by habitat, PBR was calculated. The farthest upriver sighting of tucuxis was close to the São Luiz do Tapajós rapids, whereas the farthest upriver sighting of botos was upstream of the rapids, suggesting that botos move upstream through the rapids. Estimated abundance of tucuxis (3372 ind., CV = 0.38) was twice as high as that estimated for botos (1815 ind., CV = 0.4). The PBR ranged from 11 to 18 ind. for boto and 21 to 34 for tucuxi. Throughout this study, we identified low abundances of river dolphins compared to other Amazon rivers. Boto may not be sustainable at a population level, due primarily to population fragmentation which would result from the construction of the proposed dams. Precautionary measures are urgently needed before construction of dams begins in the Tapajós River.
Great efforts have been made to preserve manatees. Recently, a hybrid zone was described between Trichechus inunguis (TIN) and the Trichechus manatus manatus (TMM) in the Amazon estuary. Cytogenetic data on these sirenians are limited, despite being fundamental to understanding the hybridization/introgression dynamics and genomic organization in Trichechus. We analyzed the karyotype of TMM, TIN, and two hybrid specimens (“Poque” and “Vitor”) by classical and molecular cytogenetics. G-band analysis revealed that TMM (2n = 48) and TIN (2n = 56) diverge by at least six Robertsonian translocations and a pericentric inversion. Hybrids had 2n = 50, however, with Autosomal Fundamental Number (FNA) = 88 in “Poque” and FNA = 74 in “Vitor”, and chromosomal distinct pairs in heterozygous; additionally, “Vitor” exhibited heteromorphisms and chromosomes whose pairs could not be determined. The U2 snDNA and Histone H3 multi genes are distributed in small clusters along TIN and TMM chromosomes and have transposable Keno and Helitron elements (TEs) in their sequences. The different karyotypes observed among manatee hybrids may indicate that they represent different generations formed by crossing between fertile hybrids and TIN. On the other hand, it is also possible that all hybrids recorded represent F1 and the observed karyotype differences must result from mechanisms of elimination.
Behavioral training is a method used in institutions that keep captive animals to assist in husbandry and health assessment issues. It consists of training animals using positive reinforcement to perform behaviors that facilitate veterinary procedures without the use of physical restraint or drugs, thereby improving animal welfare. A female Antillean manatee (Trichechus manatus manatus), eight years old, weighing approximately 400kg and measuring 266cm, was the subject of this study. The training method used was operant conditioning with positive reinforcement, which encourages the animal to cooperate during veterinary inspections. The animal was trained that every time it performed a commanded behavior correctly, it would be rewarded with food and verbal praise. Furthermore, just prior to the moment of the reward a whistle was sounded; thus the animal associated this sound with the correct performance of the commanded behavior. To control the body position, the animal was trained by operant conditioning to touch a target. Our subject was trained in two stages, to perform necessary behaviors to collect biological samples (e.g. blood). Some of the possible factors influencing the training sessions were evaluated, such as the identity of the keeper, the impact of sounds and the number of days between training sessions. Only the identity of the keeper was found to influence training sessions. Our subject rapidly learned to express a number of commanded behavior patterns to assist its management in captivity. Therefore we consider this method to have been successful. We consider this method indispensable when managing large endangered species in captivity, as training reduces stress for the animal and reduces risk to its human caregivers. Finally, the application of this method will allow us to collect more biological data about this endangered species.RESUMO: O treinamento comportamental é um método que vem sendo utilizado em instituições mantenedoras de animais em cativeiro. Consiste no desenvolvimento de um repertório comportamental, visando facilitar o acesso veterinário sem o uso de contenção física ou química, reduzindo o comprometimento do bem-estar animal. Uma fêmea de peixe-boi marinho (Trichechus manatus manatus), com oito anos de idade no momento do experimento, cerca de 400kg de peso e medindo 266cm de comprimento total foi o animal em estudo. Utilizou-se o condicionamento operante como técnica de treinamento, onde estimula-se, de forma positiva, a cooperação do animal durante o manejo veterinário. A cada vez que o animal executava o comportamento que lhe foi solicitado, recebia recompensas, como por exemplo alimentos e frases de incentivo. Simultaneamente, um apito era acionado para estabelecer uma associação entre comportamento e recompensa. Foi utilizado um alvo para orientar o animal a posicionar-se na forma desejada. A fêmea foi treinada, durante duas fases, a exibir comportamentos necessários para a coleta de amostras biológicas (por exemplo, sangue). Foram avaliados fatores de possível influência n...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.