Banca de QUALIFICAÇÃO: Thaysa Costa Hurtado

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : Thaysa Costa Hurtado
DATA : 08/04/2026
HORA: 12:00
LOCAL: CELBE no formato virtual
TÍTULO:

Mercury in the Amazon: Evidence of Bioaccumulation in Aquatic Mammals

PALAVRAS-CHAVES:

Amazon, Freshwater, Bioaccumulation, Contamination, Ecotoxicology, Toxic metals

PÁGINAS: 96
GRANDE ÁREA: Ciências Biológicas
ÁREA: Ecologia
SUBÁREA: Ecologia Aplicada
RESUMO:

Mercury (Hg) contamination in Amazonian aquatic mammals is a highly relevant topic, involving ecological and physiological effects, as well as important implications for conservation. This thesis is structured in three scientific articles, which combine an approach of studies directed at key species of Amazonian fauna, providing a scientific basis for environmental monitoring and the formulation of conservation strategies. The first article presents a systematic review and meta-analysis on the bioaccumulation and effects of Hg in aquatic and semi-aquatic freshwater mammals of the orders Carnivora, Rodentia, and Cetacea. The synthesis of 19 studies revealed significant differences in total mercury (THg) concentrations among biological tissues, with the liver showing the highest averages (1.88 ± 1.26 µg/g) and muscle the lowest (0.22 ± 0.19 µg/g). Furthermore, relevant neurotoxic effects were identified in species such as Lontra canadensis. The high heterogeneity among the studies (I² = 100%) reflects methodological and ecological variations, as well as highlighting critical knowledge gaps in South America, where only two studies included Amazonian species (Inia spp. and Pteronura brasiliensis). This quantitative approach reinforces the role of meta-analysis as an essential tool for integrating dispersed data and understanding bioaccumulation patterns on a continental scale. The second article focuses on the Amazonian manatee (Trichechus inunguis), the only exclusively freshwater and herbivorous sirenian in the Amazon. Analysis of blood and skin samples from individuals kept at the National Institute for Amazonian Research (INPA) revealed higher concentrations of THg in pups (4.14 ± 0.94 µg/L in blood) and greater cutaneous accumulation in adults (1.43 ± 0.37 µg/kg), suggesting tissue redistribution processes over time. Methylmercury (MeHg), the most toxic and bioavailable fraction of Hg, represented more than 89% of the total content in both matrices, indicating chronic exposure. Although the observed concentrations are below the toxicity limits established by international agencies, the results highlight the potential risks associated with chronic contamination in a vulnerable species, reinforcing its role as a sentinel species for environmental monitoring in the Amazon. The third article addresses the concentration of THg in the giant otter (Pteronura brasiliensis), a top predator and important trophic regulator, whose high position in the food chain makes it particularly susceptible to Hg biomagnification. Its wide distribution in the Amazon, coupled with its high sensitivity to environmental disturbances, characterizes the species as a suitable ecological model for investigating the ecotoxicological effects of Hg in aquatic ecosystems. In an integrated manner, the three articles demonstrate that the bioaccumulation of Hg in manatees and giant otters reflects both the complexity of Amazonian trophic networks and the impacts of anthropogenic pressures, such as mining, deforestation, and alterations in hydrological regimes. This study contributes to the advancement of knowledge about the ecotoxicology of aquatic mammals in the Amazon, with an emphasis on Hg as a toxic metal, and highlights the need for monitoring programs capable of integrating science, conservation, and public policies, through the use of sentinel species, the integration of biological and environmental data, and the strengthening of the control of anthropogenic sources of Hg. Aligned with the Sustainable Development Goals (SDG 3 and SDG 14), this thesis provides relevant subsidies aimed at promoting the One Health of Amazonian ecosystems and associated biodiversity.

MEMBROS DA BANCA:
Presidente - 83200001 - AUREA REGINA ALVES IGNACIO
Interna - 110049004 - MARIA APARECIDA PEREIRA PIERANGELI
Interno - 118181001 - WILKINSON LOPES LAZARO
Externa à Instituição - 056.582.857-63 - DANIELE KASPER - UFMG
Externo à Instituição - JOAO HENRUQUE FERNANDES AMARAL - UR