How do extreme fluctuations in water level affect fish condition in Amazonian Floodplain Lakes?

The annual flood pulse is a defining feature of Amazonian floodplain lakes, creating a highly variable environment that influences resource availability, such as food and habitat. These cyclical changes necessitate a high degree of adaptability among fish species, many of which have evolved specialized strategies to cope with the fluctuating conditions. In 2023, the Amazon basin experienced a record-breaking drought event, leading to mass mortality of Amazonian fish and other wildlife.

The effect of environmental factors on transepithelial potential in a model Amazonian teleost, the tambaqui (Colossoma macropomum): Implications for sodium balance in harsh environments.

The tambaqui (Colossoma macropomum, G. Cuvier 1818) thrives both in the ion-poor waters of the Amazon and in commercial aquaculture. In both, environmental conditions can be harsh due to low ion levels, occasional high salt challenges (in aquaculture), low pH, extreme PO levels (hypoxia and hyperoxia), high PCO levels (hypercapnia), high ammonia levels (in aquaculture), and high and low temperatures.

Is the air-breathing organ a significant route for CO excretion during aquatic hypercapnia in the pirarucu, Arapaima gigas?

The pirarucu is one of the very few obligate air-breathing fish, employing a gigantic, highly vascularized air-breathing organ (ABO). Traditionally, the ABO is thought to serve mainly for O uptake (ṀO), with the gills providing the major route for excretion of CO (ṀCO) and N-waste. However, under aquatic hypercapnia, a common occurrence in its natural environment, branchial ṀCO to the water may become impaired.

Morphological changes in eggs and embryos of Aedes aegypti (Diptera: Culicidae) exposed to predicted climatic scenarios for the year 2100 in the Central Amazon.

According to the IPCC, by the year 2100, rises in global temperature could reach up to 5 °C above current averages. On a planet-wide scale, this is one of the effects of climate changes that could have repercussions on the biological cycle of Aedes aegypti, the main arbovirus vector in urban environments and a transmitter of the arboviruses that cause dengue, Zika, chikungunya and urban yellow fever. The objective of this study was to evaluate morphological changes in Ae.

Amazon tropical fishes of commercial interest show human-cell contamination but no SARS-CoV-2 in a real-life scenario.

Background: Amazonas was one of the most impacted Brazilian states by the COVID-19 pandemic. Mortality rates were high, and the health systems collapsed. It is important to identify possible intermediate reservoirs to avoid animal-to-human contamination.

Simulated climate change and atrazine contamination can synergistically impair zebrafish testicular function.

Elements that interfere with reproductive processes can have profound impacts on population and the equilibrium of ecosystems. Global warming represents the major environmental challenge of the 21st century, as it will affect all forms of life in the coming decades. Another coexisting concern is the persistent pollution by pesticides, particularly the herbicide Atrazine (ATZ), which is responsible for a significant number of contamination incidents in surface waters worldwide.

Effects of climate change and mixtures of pesticides on the Amazonian fish Colossoma macropomum.

Several studies highlighted the complexity of mixing pesticides present in Amazonian aquatic environments today. There is evidence that indicates that ongoing climate change can alter the pattern of pesticide use, increasing the concentration and frequency of pesticide applications. It is known that the combination of thermal and chemical stress can induce interactive effects in aquatic biota, which accentuates cell and molecular damage.

In vivo exposure to high temperature compromises quality of the sperm in Colossoma macropomum.

Increases in temperature can affect the reproduction of fish by decreasing the quality of gametes for fertilization. Therefore, this study aimed to evaluate the in vivo effect of temperature on the production and sperm quality of Colossoma macropomum, which is an economically relevant species for Brazil, and other countries. Broodstock were exposed for 10 days at temperatures of 29 °C (n = 4) and 35 °C (n = 4).

Important role of endogenous microbial symbionts of fish gills in the challenging but highly biodiverse Amazonian blackwaters.

Amazonian blackwaters are extremely biodiverse systems containing some of Earth's most naturally acidic, dissolved organic carbon -rich and ion-poor waters. Physiological adaptations of fish facing these ionoregulatory challenges are unresolved but could involve microbially-mediated processes. Here, we characterize the physiological response of 964 fish-microbe systems from four blackwater Teleost species along a natural hydrochemical gradient, using dual RNA-Seq and 16 S rRNA of gill samples.

Ammonia Increases the Stress of the Amazonian Giant in a Climate Change Scenario.

Ammonia is toxic to fish, and when associated with global warming, it can cause losses in aquaculture. In this study, we investigated the physiological and zootechnical responses of to the current scenarios and to RCP8.5, a scenario predicted by the IPCC for the year 2100 which is associated with high concentrations of environmental ammonia (HEA).

Bacterioplankton Communities in Dissolved Organic Carbon-Rich Amazonian Black Water.

The Amazon River basin sustains dramatic hydrochemical gradients defined by three water types: white, clear, and black waters. In black water, important loads of allochthonous humic dissolved organic matter (DOM) result from the bacterioplankton degradation of plant lignin. However, the bacterial taxa involved in this process remain unknown, since Amazonian bacterioplankton has been poorly studied.

Correlation between caffeine and coprostanol in contrasting Amazonian water bodies.

The evaluation of contamination by domestic sewage is relevant in the Amazon region; however, it has neither been well-developed nor accompanied by research or monitoring programs. In this study, caffeine and coprostanol as indicators of sewage were investigated in water samples from Amazonian water bodies that crisscross the city of Manaus (Amazonas state, Brazil) and cover regions with distinct main land uses such as high-density residential, low-density residential, commercial, industrial, and environmental protection areas. Thirty-one water samples were studied based on their dissolved and particulate organic matter (DOM and POM) fractions.

Vitellogenin Ab structure of the amazonian Arapaima gigas.

The vitellogenin is composed by polypeptides that are precursors of egg yolk proteins that provides embryo and larvae nutrition. The mRNA encoding for vitellogenin Ab (Vtg-Ab; 4,536 bp long and 1,512 amino acids) were obtained by RNA-Seq library sequencing of pirarucu gonads. The Vtg-Ab sequences had high homology with Vtgs of other three teleosts species of the order Osteoglossiformes.

Impact of high temperature, CO and parasitic infection on inflammation, immunodepression and programmed cell death in Colossoma macropomum at the transcriptional level.

The production of tambaqui Colossoma macropomum has recently reached a milestone, being considered the main native species produced in South American continental waters. Despite the importance of this fish, its immunity is poorly understood, and global warming could pose severe risks to its health as increasing water temperature leads to an increase in the incidence of parasitic diseases. In an experimental context based on the high-emission scenario of the 5th Intergovernmental Panel on Climate Change (IPCC) report, we evaluated the synergistic effect of exposure to the extreme climate change scenario (RCP8.

Tissue distribution of appetite regulation genes and their expression in the Amazon fish Colossoma macropomum exposed to climate change scenario.

Climate change leads to an increase in water acidification and temperature, two environmental factors that can change fish appetite and metabolism, affecting fish population in both wild and aquaculture facilities. Therefore, our study tested if climate change affects gene expression levels of two appetite-regulating peptides - Neuropeptide Y (NPY) and Cholecystokinin (CCK) - in the brain of tambaqui, Colossoma macropomum. Additionally, we show the distribution of these genes throughout the body.

Climate change affects the parasitism rate and impairs the regulation of genes related to oxidative stress and ionoregulation of Colossoma macropomum.

Global climate change represents a critical threat to the environment since it influences organismic interactions, such as the host-parasite systems, mainly in ectotherms including fishes. Rising temperature and CO are predicted to affect this interaction other and critical physiological processes in fish. Herein, we investigated the effects of different periods of exposure to climate change scenarios and to two degrees of parasitism by monogeneans in the host-parasite interaction, as well as the antioxidant and ionoregulatory responses of tambaqui (Colossoma macropomum), an important species in South American fishing and aquaculture.

Involvement of purinergic system and electron transport chain in two species of cichlids from the Amazon basin exposed to hypoxia.

The Amazonian aquatic ecosystem undergoes seasonal variations and daily changes that directly affect the availability of oxygen. During the day the levels of oxygen can reach supersaturation, and at night can drop to zero. In this way, aquatic organisms are exposed daily to physiological challenges regarding the availability of oxygen.

Copper and cadmium impair sperm performance, fertilization and hatching of oocytes from Amazonian fish Colossoma macropomum.

The contamination of aquatic environments by transition metals can have a direct influence on the reproductive process of several organisms in the aquatic biota. This study aimed to evaluate the effect of cadmium and copper on the sperm of tambaqui (Colossoma macropomum). Male (n = 4) and female (n = 4) specimens of C.

Aerobic Metabolism Impairment in Tambaqui (Colossoma macropomum) Juveniles Exposed to Urban Wastewater in Manaus, Amazon.

The main purpose of the present study was to investigate the potential use of metabolic parameters as non-specific biomarkers of pollution. The Igarapé do Quarenta is a small urban river crossing an industrial area in the city of Manaus, Amazon, and receives the city wastewater without treatment. The fish tambaqui (Colossoma macropomum) were exposed to water collected from two different sites of that stretch for 96 h.

Understanding the Science Surrounding Environmental Consequences and Rehabilitation Actions Stemming from Brazil's Fundão Tailing Dam Rupture.

Collapse of the Fundão tailings dam in November 2015 in Minas Gerais, Brazil, resulted in the release of approximately 36 million cubic meters of primarily clay and fine sand-sized particles to the environment. The spill event extended over 600 km of the Rio Doce catchment and affected terrestrial and aquatic ecosystems and compromised socioeconomic activities throughout the watershed. Numerous monitoring programs and research investigations in the catchment since that time contribute to better understanding of the environmental consequences and plans for rehabilitation of the landscape.

Disturbance of oxidant/antioxidant status and impairment on fillet fatty acid profiles in Brycon amazonicus subjected to acute heat stress.

Amazon fish are vulnerable to climate change. Current temperature increases in Amazonian rivers are likely to continue in the coming years. Elevated temperatures impair homeostasis and subject fish to oxidative stress; nevertheless, the effects of elevated temperature on plasma and muscle oxidative stress as well as fillet fatty acid composition in matrinxã (Brycon amazonicus) remain unknown.

Fish Skin and Gut Microbiomes Show Contrasting Signatures of Host Species and Habitat.

Teleost fish represent an invaluable repertoire of host species to study the factors shaping animal-associated microbiomes. Several studies have shown that the phylogenetic structure of the fish gut microbiome is driven by species-specific (e.g.

How will farmed populations of freshwater fish deal with the extreme climate scenario in 2100? Transcriptional responses of Colossoma macropomum from two Brazilian climate regions.

Tambaqui (Colossoma macropomum Cuvier, 1818) is an endemic fish of the Amazon and Orinoco basins, and it is the most economically important native species in Brazil being raised in five climatically distinct regions. In the face of current global warming, environmental variations in farm ponds represent additional challenges that may drive new adaptive regional genetic variations among broodstocks of tambaqui. In an experimental context based on the high-emission scenario of the 5th Intergovernmental Panel on Climate Change (IPCC) report, we used two farmed tambaqui populations to test this hypothesis.

Purine levels and purinergic signaling in plasma and spleen of Brycon amazonicus exposed to acute heat thermal stress: An attempt to regulate the immune response.

Amazon fish are vulnerable to climate change. Several lines of evidence suggest that the temperature of Amazonian rivers will increase in the coming years. Elevated temperature disturbs homeostasis and subjects fish to physiological stress; however, the effects of temperature on immunity remain poorly understood, particularly those effects involving purinergic signaling.