Federal University of Western Pará

Canine distemper (CD) is a severe infectious disease of dogs caused by the Canine Distemper Virus (CDV), a member of the genus Morbillivirus. This study aimed to investigate the circulation of CDV in dogs housed in two public kennels located in Belém in the Amazon region of Brazil. Fecal and rectal swab samples were collected between March 2019 and April, 2020. A one-step RT-PCR was initially standardized for CDV detection in fecal samples. Positive strains were partially sequenced using Sanger sequencing. A prevalence rate of 23.6% was observed, with 18.4% in healthy dogs and 46.7% in dogs with diarrhea. Phylogenetic analysis revealed that the samples were closely related to European strains and demonstrated the circulation of Brazilian strains belonging to the Europe 1/South America 1 lineage. This investigation successfully established a CDV diagnostic technique using RT-PCR in blood, feces, and urine samples. This study also verified the circulation of the virus in dogs from public kennels in an important city in the Brazilian Amazon.

Recent evidence suggests that the ecological footprints of pre-Columbian Indigenous peoples in Amazonia persist in modern forests. Ecological impacts resulting from European colonization c. 1550 CE and the Amazonian Rubber Boom c. 1850 to 1920 CE are largely unexplored but could be important additive influences on forest structure and tree species composition. Using environmental niche models, we show the highest probabilities of pre-Columbian and colonial occupation sites, and hence human-induced ecological influences, occurred in forests along rivers. In many areas, the predicted pre-Columbian and colonial distributions overlap spatially with the potential for superimposed ecological influences. Environmental gradients are known to structure Amazonian vegetation composition, but they are also strong predictors of past human influence, both spatially and temporally. Our comparisons of model outputs with relative abundances of Amazonian tree species suggest that pre-Columbian and colonial-period ecological legacies are associated with modern forest composition.

Hydroelectric reservoirs are often responsible for releasing total mercury (THg) into aquatic ecosystems. There is limited information on the influence of hydrosystem gradients and fluvial regimes on THg distribution. This study aimed to investigate the influence of vertical gradients, hydrosystem gradients, and fluvial regime on THg distribution in water and plankton in the Curuá-Una reservoir, Brazilian Amazon. Samplings were carried out in four fluvial periods: low-water, rising-water, high-water, and falling-water periods. THg levels were determined by cold vapor atomic fluorescence spectroscopy. Physicochemical conditions of the reservoir varied between lacustrine, transition, and riverine zones. Water transparency was greatest in the lacustrine zone (2.5 m), where the depth reaches 18 m. Conductivity (46.8 μS cm^-1) and dissolved oxygen (7.7 mg L^-1) were higher in the riverine zone in the falling-water period. During the rising-water period, THg was higher in the hypolimnion (8.8 ng L^-1) than in the epilimnion (6.2 ng L^-1). THg increased in the low-water period (7.9 ± 1.2 ng L^-1). The results demonstrate the influence of water stratification, hypoxia, and fluvial regime on THg dynamics. In the low-water period, the hypoxic hypolimnion favored the increase in HgT. Hg release was also found to be influenced by deforestation and human activities, with higher concentrations observed in pasture and agricultural areas, affecting local aquatic biota. THg dynamics are influenced by hydrological and hydrometric processes. Therefore, these factors should be considered in environmental studies aimed at preserving Amazonian biodiversity.