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.

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.

Acute CO tolerance in fishes is associated with air breathing but not the Root effect, red cell βNHE, or habitat.

High CO (hypercapnia) can impose significant physiological challenges associated with acid-base regulation in fishes, impairing whole animal performance and survival. Unlike other environmental conditions such as temperature and O, the acute CO tolerance thresholds of fishes are not understood. While some fish species are highly tolerant, the extent of acute CO tolerance and the associated physiological and ecological traits remain largely unknown.

Investigating the mechanisms of dissolved organic matter protection against copper toxicity in fish of Amazon's black waters.

We investigated how natural dissolved organic matter (DOM) of the Rio Negro (Amazon) affects acute copper (Cu) toxicity to local fish: the cardinal tetra (Paracheirodon axelrodi) and the dwarf cichlid (Apistogramma agassizii). It is established that Cu complexation with DOM decreases Cu bioavailability (and thus toxicity) to aquatic organisms, as conceptualized by the Biotic Ligand Model (BLM). However, we also know that Rio Negro's DOM can interact with fish gills and have a beneficial effect on Na homeostasis, the main target of acute Cu toxicity in freshwater animals.

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.

Take time to look at the fish: Behavioral response to acute thermal challenge in two Amazonian cichlids.

Critical thermal maximum (CT ) is often used as an index of upper thermal tolerance in fishes; however, recent studies have shown that some fishes exhibit agitation or avoidance behavior well before the CT is reached. In this study, we quantified behavioral changes during CT trials in two Amazonian cichlids, Apistogramma agassizii and Mesonauta insignis. The thermal agitation temperature (T ) was recorded as the temperature at which fish left cover and began swimming in an agitated manner, and four behaviors (duration of sheltering, digging, activity, and aquatic surface respiration [ASR]) were compared before and after T .

Colossoma macropomum-A tropical fish model for biology and aquaculture.

Tambaqui, a species native to the Amazon and Orinoco Basins and their tributaries, has a history marked by biological resilience that makes this species a model for studies focused on ecology, physiology, and fish farming. In addition, it is of economic interest, due to its favorable characteristics for production in farms and its unique flavor. As the tambaqui responds in a unique way to several environmental disturbances of natural origin, the species is often used in environmental studies.

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.

Extreme climate scenario and parasitism affect the Amazonian fish Colossoma macropomum.

Global warming caused by greenhouse gases accumulation, in particular carbon dioxide, is the major current environmental challenge, as it will affect all life forms over the next decades. Aquaculture, a fast growing food production sector, is already facing the effects of global warming. The fish immune system is expected to be especially affected by increased temperature and carbon dioxide, mainly when associated to infectious diseases outbreaks.

Preferential intracellular pH regulation is a common trait amongst fishes exposed to high environmental CO.

Acute (<96 h) exposure to elevated environmental CO (hypercarbia) induces a pH disturbance in fishes that is often compensated by concurrent recovery of intracellular and extracellular pH (pH and pH, respectively; coupled pH regulation). However, coupled pH regulation may be limited at CO partial pressure ( ) tensions far below levels that some fishes naturally encounter. Previously, four hypercarbia-tolerant fishes had been shown to completely and rapidly regulate heart, brain, liver and white muscle pH during acute exposure to >4 kPa  (preferential pH regulation) before pH compensation was observed.

The Effects of Natural Suspended Solids on Copper Toxicity to the Cardinal Tetra in Amazonian River Waters.

The aim of the present study was to characterize the effects of particles on metal aquatic toxicity in a tropical system. To this end, we investigated the effects of natural suspended solids on copper (Cu) geochemistry and acute toxicity to the cardinal tetra (Paracheirodon axelrodi), in 2 Amazonian rivers with different total suspended solids (TSS) levels: the Rio Negro (low TSS ~ 8 mg L ) and the Rio Solimões (high TSS ~ 70 mg L ). The effect of particles on Cu aqueous geochemistry was assessed by measuring total, dissolved, and free ionic Cu concentrations in filtered (<0.

Sewage contamination of Amazon streams crossing Manaus (Brazil) by sterol biomarkers.

Sewage pollution is a principal factor of decreasing water quality, although it has not been considered a real impact in Amazonia that is still considered a pristine environment around the world. Thus, this study aimed to assess the levels of sewage contamination in sediments from three streams crossing Manaus - a Brazilian city of 2,403,796 inhabitants in the heart of the Amazon rain forest. Cholesterol, cholestanol, brassicasterol, ergosterol, stigmasterol, β-sitosterol, campesterol, stigmastanol, coprostanol, and epicoprostanol levels were determined by liquid chromatography tandem mass spectrometry (LC-MS/MS).

The physiology of the Tambaqui (Colossoma macropomum) at pH 8.0.

The Tambaqui is a model neotropical teleost which is of great economic and cultural importance in artisanal fisheries and commercial aquaculture. It thrives in ion-poor, often acidic Amazonian waters and exhibits excellent regulation of physiology down to water pH 4.0.