Studies about the hydrodynamic behavior in the lower Amazon River remain scarce, despite their relevance and complexity, and the Water Residence Time (Rt) of this Amazonian estuary remains poorly unknown. Therefore, the present study aims to numerically simulate three seasonal Rt scenarios based on a calibrated hydrodynamic numerical model (SisbaHiA) applied to a representative stretch of the lower Amazon River. The following methodological steps were performed: (a) establishing experimental water flow in natural channels; (b) statistically test numerical predictions (tidal range cycles for different hydrologic periods); and (c) simulating velocity fields and water discharge associated with Rt numerical outputs of the hydrodynamic model varied from 14 ≤ Rt ≤ 22 days among different seasonal periods. This change has shown the significant influence of hydrologic period and geomorphological features on Rt. Rt, in its turn, has shown significant spatial heterogeneity, depending on location and stretch of the channels. Comparative analyses between simulated and experimental parameters evidenced statistical correlations higher than 0.9. We conclude that the generated Rt scenarios were consistent with other similar studies in the literature. Therefore, they depicted the applicability of the hydrodynamics to the conservation of the Amazonian aquatic ecosystem, as well as its relevance for biochemical and pollutant dispersion studies, which still remain scarce in the literature.

O objetivo deste estudo foi quantificar a variabilidade espacial-temporal de 20 parâmetros físicos, químicos e microbiológicos da qualidade da água (incluindo o índice de estado trófico - IET) no Baixo Rio Jari, Amapá, típico de ecossistemas de várzea. Amostras de água foram coletadas trimestralmente em um trecho de 80 km de extensão do rio, entre setembro de 2013 e junho de 2014. Após análises, esses parâmetros foram comparados com valores estabelecidos pela Resolução CONAMA nº 357/2005 (Classe 2). Análises multivariadas (correlação, Kruskall-Wallis e cluster hierárquico) mostraram que o único parâmetro que variou espacialmente foi o oxigênio dissolvido (OD) (p<0,05), devido à forte influência da reaeração no trecho. Por outro lado, os demais parâmetros - cor, turbidez, condutividade elétrica, demanda bioquímica de oxigênio (DBO), NH₃, P, pH, SO₄, Mg, Cl^-, coliformes termotolerantes (CT), Escherichia coli e clorofila-a - apresentaram apenas variação temporal significativa (p<0,05). Conclui-se que variação do IET ocorreu entre oligotrófico, mesotrófico e ultraoligotrófico, e os parâmetros cor, CT e E. coli estavam em não conformidade com a legislação, sugerindo influência relativa, mas significativa, tanto de impactos ambientais (urbanos, indústrias e da usina hidrelétrica Santo Antônio do Jari) quanto hidrológicos. Isso explica não só a variação sazonal de CT, E. coli e cor no período mais chuvoso (p<0,05), mas também a correlação entre cor, turbidez, temperatura, OD, Cl^-, NH₃, Mg, DBO, SO₄, pH, E. coli, CT e clorofila-a ao longo do ciclo hidrológico e dinâmica sazonal (p<0,05), influenciando indiretamente o comportamento sazonal do IET (p<0,05).

Chrysomya albiceps (Wiedemann, 1819), a species of blowfly (Diptera, Calliphoridae), historically distributed throughout Southern Europe, has recently dispersed to cooler regions in Europe, which is an intriguing phenomenon. In this work, we used Maxent software to formulate climate suitability using a machine learning technique to investigate this fact. The bioclimatic variables that best explained the climate suitability were Annual Mean Temperature (67.7%) and Temperature Annual Range (21.4%). We found that C. albiceps is climatically suitable for several parts of Europe, except for high altitude areas like the Swiss Alps. In warmer countries such as Portugal, Spain and Italy, the entire coastal territory was the most suitable for the species. Future scenario models show that in these eastern countries and some northern areas, climate suitability has increased. This increase is reinforced when comparing the gains and losses in climate suitability between the present-day model and the future scenario models. These changes are most likely caused by changes in temperature, which is the main explanatory factor among the tested variables, for the climate suitability. As one of the most important species in forensic contexts and a potential myiasis agent, the expansion of C. albiceps to new locations cannot be neglected, and its expansion must be carefully monitored.

The rise in the global mean sea level (MSL) is a significant consequence of climate change, attributed to both natural and anthropogenic forces. This phenomenon directly affects the dynamic equilibrium of Earth’s oceanic and estuarine ecosystems, particularly impacting the Amazon estuary. In this study, a numerical model was employed to investigate the long-term impacts of MSL fluctuations on key hydrodynamic parameters crucial to regional environmental dynamics. Our investigation was based on scenarios derived from Representative Concentration Pathways (RCPs) and Coupled Model Intercomparison Project Phase 5 (CMIP5) projections, incorporating MSL variations ranging from 30 to 150 cm above the current mean level. Following careful calibration and validation procedures, which utilized observational and in situ data, notably from field expeditions conducted in 2019, our simulations unveiled significant impacts on certain hydrodynamic parameters. Specifically, we observed a pronounced increase in diurnal tidal amplitude (p < 0.05) within the upstream sections of the North and South channels. Additionally, discernible alterations in water renewal rates throughout the estuary were noted, persisting for approximately 2 days during the dry season (p < 0.05). These findings provide valuable insights into the vulnerability of key parameters to hydrologic instability within the Amazonian coastal region. In conclusion, this study represents a pivotal scientific endeavor aimed at enhancing the preservation of aquatic ecosystems and advancing the environmental knowledge of the Lower Amazon River, with the goal of proactively informing measures to safeguard the current and future sustainability of these vital ecosystems.

In 2013, a slope slide took place at the Santana-AP channel that links to the Lower Amazon River’s North Channel, resulting in the sudden collapse of a substantial section of the Port of Santana and its infrastructure. This area houses liquid bulk terminals and pipelines with high pollution potential. The objective of the research is to evaluate the potential environmental impacts of an eventual oil spill in the very short term using a numerical hydrodynamic simulation model coupled with that of pollutant dispersion. The SisBaHiA^® software, experimentally calibrated using acoustic methods (ADCP), was used to generate hypothetical scenarios in these areas with a substantial risk of landslides. Two hydrological scenarios stand out in the simulations: (a) November S-1 (dry) and (b) May S-2 (rainy). In S-1, the plume dispersion was higher during flood tides S-1a and S-1b, reaching 4 h urban slope areas, river mouths, tributaries (Matapi and Vila Nova), and environmental protection areas. At S-2, the plume spread was greater during the ebb tides S-2c and S-2d, affecting Macapá’s water supply system 12 h after the accident. The scenarios suggest the existence of high risks associated with the study hypotheses. The dispersion of the plume is directly proportional to the flow, indicating that local hydrodynamics is probably the most relevant dispersive factor. We conclude that the mitigation time for more severe effects is critical in the first 4 h because the coastal geographic feature tends to keep the plume in the Santana channel.