Efeitos subletais da poluição por petróleo e derivados sobre peixes da Amazônia (Amazonas, Brasil)

The present work analyzed the changes in biomarkers of exposure and effects in fishes of the Amazon, especially from Negro river, exposed to the crude oil and derivatives; and verified the responses of these biomarkers according to the physical and chemical characteristics of the water. The set of biomarkers, EROD; GST; SOD and CAT; serum SDH; LPO, erythrocytic DNA damage and HPA bile metabolites, proved to be efficient in demonstrate the Benzo[a]Pyrene (B[a]P) effects in tambaqui, and can be considered a promising set of biomarkers to evaluate the effects of the crude oil and derivatives in Amazon fishes. The chemical dispersion of the Urucu crude oil resulted in the increase of toxicity to tambaqui, as seen by the increased responses of a set of biomarkers: EROD; GST; SOD and CAT; serum SDH; LPO, erythrocytic DNA damage and HPA bile metabolites. However, the magnitude of the responses of these biomarkers was higher in specimens acclimated to natural water from the Negro river (low ion availability and high dissolved organic carbon (DOC) concentration). The accidental oil spill in the Negro river (São Raimundo harbor) caused increase in the biomarkers of exposure and effect in two resident cichlid fish species; this increase was not related with the reduction of the Policlic Aromatic Hydrocarbons (PAH) concentration in the water column. Moreover, the PAH concentration in water along with the DOC concentration were related to responses of these biomarkers, as observed through the multivariate analyzes. Thereby, it is possible to say that the set of studied biomarkers in fishes from the Negro river is of great relevance to evaluate the quality of this environment after the contamination of the Negro river with crude oil and derivatives.A presente tese teve como objetivo geral avaliar as respostas dos biomarcadores de exposição e efeito em peixes da região amazônica, mais especificamente do Rio Negro, expostos ao petróleo e derivados e, ainda, verificar a resposta desses biomarcadores em função da presença do petróleo em águas com diferentes características físico-químicas. O conjunto de biomarcadores, enzimas EROD; GST; SOD e CAT hepáticas, a enzima SDH plasmática, a concentração da LPO hepática, os danos no DNA dos eritrócitos, juntamente com a análise dos metabólitos de HPA na bile, se mostraram eficientes em indicar os efeitos do B[a]P no tambaqui, podendo ser considerado um grupo de biomarcadores promissor para se avaliar os efeitos dos HPA do petróleo em peixes da região amazônica. A dispersão química do óleo cru de Urucu-AM causou um aumento na toxicidade, observada nas respostas dos biomarcadores. No entanto, as respostas foram observadas em maior magnitude nos animais expostos ao óleo cru quimicamente dispersado em água natural do Rio Negro. O derramamento acidental do derivado de petróleo CAP no Rio Negro (porto São Raimundo) causou alterações dos biomarcadores de exposição e efeito analisados em duas espécies de ciclídeos residentes, os quais não apresentaram diminuição das respostas em função da diminuição da concentração dos HPA dissolvidos na água. Além disso, a concentração dos HPA na água juntamente com a concentração de COD foi responsável pelas respostas dos biomarcadores avaliados, como visto na análise multivariada dos dados. Dessa forma, podemos sugerir que o conjunto de biomarcadores estudados nos peixes do Rio Negro é de suma importância para avaliarmos a qualidade desse ambiente em função da contaminação por HPA do petróleo e derivados

Roundup® exposure promotes gills and liver impairments, DNA damage and inhibition of brain cholinergic activity in the Amazon teleost fish Colossoma macropomum

Roundup Original® (RD) is a glyphosate-based herbicide used to control weeds in agriculture. Contamination of Amazon waters has increased as a consequence of anthropogenic pressure, including the use of herbicides as RD. The central goal of this study was to evaluate the toxic effects of RD on juveniles of tambaqui (Colossoma macropomum). Our findings show that biomarkers in tambaqui are organ specific and dependent on RD concentration. Alterations in gills structural and respiratory epithelium were followed by changes in hematological parameters such as concentration of hemoglobin, particularly in fish exposed to the higher concentration tested (75% of RD LC50 96h). In addition, both RD concentrations affected the biotransformation process in gills of tambaqui negatively. Instead, liver responses suggest that a production of reactive oxygen species (ROS) occurred in fish exposed to RD, particularly in the animals exposed to 75% RD, as seen by imbalances in biotransformation and antioxidant systems. The increased DNA damage observed in red blood cells of tambaqui exposed to RD is in agreement with this hypothesis. Finally, both tested sub-lethal concentrations of RD markedly inhibited the cholinesterase activity in fish brain. Thus, we can suggest that RD is potentially toxic to tambaqui and possibly to other tropical fish species. © 2015 Elsevier Ltd

Influence of the natural Rio Negro water on the toxicological effects of a crude oil and its chemical dispersion to the Amazonian fish Colossoma macropomum

The increment in crude oil exploitation over the last decades has considerably increased the risk of polycyclic aromatic hydrocarbon (PAH) contamination to Amazonian aquatic environments, especially for the black water environments such as the Rio Negro. The present work was designed to evaluate the acute toxicity of the Urucu crude oil (CO), the chemically dispersed Urucu crude oil (CO + D), and the dispersant alone (D) to the Amazonian fish Colossoma macropomum. Acute toxicity tests were performed, using a more realistic approach, where fish were acclimated to both groundwater (GW), used as internal control, and natural Rio Negro water (RNW) and exposed to CO, CO + D and D. Then, biomarkers such as ethoxyresorufin-O-deethylase (EROD), superoxide dismutase (SOD), lipid peroxidation (LPO), serum sorbitol dehydrogenase (s-SDH) in liver, DNA damage in blood cells, and the presence of the benzo[a]pyrene-type, pyrene-type, and naphthalene-type metabolites in fish bile were assessed. Fish exposed to CO and CO + D, at both water types tested, presented increased biomarker responses and higher PAH-type metabolites in the bile. However, fish exposed to these treatments after the acclimation to RNW increased the levels of LPO, s-SDH (hepatotoxicity), DNA damage in blood cells (genotoxicity), and benzo[a]pyrene-type metabolites when compared to fish in GW. Our data suggests that some physicochemical properties of Rio Negro water (i.e., presence of natural organic matter (NOM)) might cause mild chemical stress responses in fish, which can make it more susceptible to oxidative stress following exposure to crude oil, particularly to those chemically dispersed. © 2016, Springer-Verlag Berlin Heidelberg

Photo-oxidation processes, properties of DOC, reactive oxygen species (ROS), and their potential impacts on native biota and carbon cycling in the Rio Negro (Amazonia, Brazil)

Given the reported degraded nature of DOC in the Rio Negro, and low oxygen, pH, and bacterial riverine levels, we hypothesized: (1) DOC would have strong humic and fulvic acid fluorescence signals with high aromaticity and large mean molecular weight; and (2) photo-oxidation rates would be slow, and reactive oxygen species (ROS) concentrations low, producing no oxidative stress in biota. We surveyed the environment and properties of DOC and explored DOC photo-oxidation and fish sensitivity to DOC products. DOC properties were investigated using absorption and fluorescence indices and parallel factor analysis (PARAFAC) of excitation–emission matrices. ROS concentrations were measured spectrophotometrically. A native fish, Hemigrammus levis, was exposed to photo-oxidizing DOC and its tissues (brain, gill, liver) assayed for changes in antioxidant and biotransformation enzymes. With respect to our hypotheses, (1) DOC was highly terrigenous, with high SAC340 values (aromaticity), high capacity to produce ROS, and high tryptophan-like fluorescence (bacterial, autochthonous signal); (2) photo-oxidation rates were appreciable, while products were related to mean UV-radiation levels (total radiation was constant). ROS levels were often higher than freshwater averages, yet fish experienced no oxidative stress. Results suggest photo-oxidation influences patterns in C-cycling, bacterial production and community dynamics between wet and dry seasons. © 2016, Springer International Publishing Switzerland

Does dissolved organic carbon from Amazon black water (Brazil) help a native species, the tambaqui Colossoma macropomum to maintain ionic homeostasis in acidic water?

To assess how the quality and properties of the natural dissolved organic carbon (DOC) could drive different effects on gill physiology, we analysed the ionoregulatory responses of a native Amazonian fish species, the tambaqui Colossoma macropomum, to the presence of dissolved organic carbon (DOC; 10 mg l −1 ) at both pH 7.0 and pH 4.0 in ion-poor water. The DOC was isolated from black water from São Gabriel da Cachoeira (SGC) in the upper Rio Negro of the Amazon (Brazil) that earlier been shown to protect a non-native species, zebrafish Danio rerio against low pH under similar conditions. Transepithelial potential (TEP), net flux rates of Na + , Cl − and ammonia and their concentrations in plasma and Na + , K + ATPase; v-type H + ATPase and carbonic anhydrase activities in gills were measured. The presence of DOC had negligible effects at pH 7.0 apart from lowering the TEP, but it prevented the depolarization of TEP that occurred at pH 4.0 in the absence of DOC. However, contrary to our initial hypothesis, SGC DOC was not protective against the effects of low pH. Colossoma macropomum exposed to SGC DOC at pH 4.0 experienced greater net Na + and Cl − losses, decreases of Na + and Cl − concentrations in plasma and elevated plasma ammonia levels and excretion rates, relative to those exposed in the absence of DOC. Species-specific differences and changes in DOC properties during storage are discussed as possible factors influencing the effectiveness of SGC DOC in ameliorating the effects of the acid exposure. © 2019 The Fisheries Society of the British Isle

The transition from water-breathing to air-breathing is associated with a shift in ion uptake from gills to gut: a study of two closely related erythrinid teleosts, Hoplerythrinus unitaeniatus and Hoplias malabaricus

The evolutionary transition from water-breathing to air-breathing involved not only a change in function of the organs of respiratory gas exchange and N-waste excretion, but also in the organs of ion uptake from the environment. A combination of in vivo and in vitro techniques was used to look at the relative importance of the gills versus the gut in Na+, Cl−, and K+ balance in two closely related erythrinid species: a facultative air-breather, the jeju (Hoplerythrinus unitaeniatus) and an obligate water-breather, the traira (Hopliasmalabaricus). The jeju has a well-vascularized physostomous swimbladder, while that in the traira is poorly vascularized, but the gills are much larger. Both species are native to the Amazon and are common in the ion-poor, acidic blackwaters of the Rio Negro. Under fasting conditions, the traira was able to maintain positive net Na+ and Cl− balance in this water, and only slightly negative net K+ balance. However, the jeju was in negative net balance for all three ions and had lower plasma Na+ and Cl− concentrations, despite exhibiting higher branchial Na+,K+ATPase and v-type H+ATPase activities. In the intestine, activities of these same enzymes were also higher in the jeju, and in vitro measurements of net area-specific rates of Na+, Cl−, and K+ absorption, as well as the overall intestinal absorption capacities for these three ions, were far greater than in the traira. When acutely exposed to disturbances in water O2 levels (severe hypoxia ~15 % or hyperoxia ~420 % saturation), gill ionoregulation was greatly perturbed in the traira but less affected in the jeju, which could “escape” the stressor by voluntarily air-breathing. We suggest that a shift of ionoregulatory capacity from the gills to the gut may have occurred in the evolutionary transition to air-breathing in jeju, and in consequence branchial ionoregulation, while less powerful, is also less impacted by variations in water O2 levels. © 2016, Springer-Verlag Berlin Heidelberg