High waterborne Mg does not attenuate the toxic effects of Fe, Mn, and Ba on Na+ regulation of Amazonian armored catfish tamoatá (Hoplosternum litoralle).

Formation water (FoW) is a by-product from oil and gas production and usually has high concentrations of soluble salts and metals. Calcium (Ca) and magnesium (Mg) have been shown to reduce the toxicity of metals to aquatic animals, and previous study showed that high waterborne Ca exerts mild effect against disturbances on Na+ regulation in Amazonian armored catfish tamoatá (Hoplosternum littorale) acutely exposed to high Fe, Mn, and Ba levels. Here, we hypothesized that high Mg levels might also reduce the toxic effects of these metals on Na+ regulation of tamoatá. The exposure to 5% FoW promoted an increase in Na+ uptake and a rapid accumulation of Na+ in all tissues analyzed (kidney

Hematological and biochemical characteristics during the transport of dog snapper Lutjanus jocu (Perciformes: Lutjanidae)

The objective of this study was to evaluate stress responses in dog snapper (Lutjanus jocu) during transport by evaluating their hematological and biochemical responses. Twenty-five wild dog snapper specimens were used in the experiment (220 ± 68 g and 24.5 ± 2.5 cm total length). Blood samples were collected prior to transport (control), and fish were placed in two transport boxes, one with anesthetic and one without anesthetic. Immediately after transport and after 24 h, blood was collected from the fish that underwent each treatment (with anesthetic and without anesthetic). Biochemical and hematological results demonstrated the inefficiency of benzocaine as a stress reliever during handling and transport. Biochemical parameters revealed the effects of stress during transport, and after 24 h, glucose levels and hematological parameters (hemoglobin, erythrocytes, leukocytes, neutrophils and MCH) showed a tendency to return to control levels. This study is the first to report stress response measurements of hematological and biochemical indicators in dog snapper, representing an important basis for the planning of future experiments involving the transport and handling of this fish species.(AU)

O objetivo desde estudo foi avaliar as repostas de estresse em dentão (Lutjanus jocu) durante o procedimento de transporte, através de respostas hematológicas e bioquímicas. Vinte e cinco exemplares selvagens de dentão foram utilizados no experimento (220 ± 68 g e 24.5 ± 2.5 cm de comprimento total). Foram realizadas coletas de sangue previamente ao transporte (controle), e os demais peixes foram acondicionados em duas caixas de transporte, uma com anestésico e outra sem anestésico. Imediatamente após o transporte e após 24 h, houve coleta de sangue para cada tratamento (com anestésico e sem anestésico). Os resultados bioquímicos e hematológicos apontam a ineficiência da benzocaína como mitigador do estresse durante o manuseio e transporte. Os parâmetros bioquímicos foram capazes de detectar o efeito do estresse durante o transporte, e após 24 h os níveis de glicose e alguns parâmetros hematológicos (hemoglobina, eritrócitos, leucócitos, neutrófilos e MCH) demonstraram uma tendência de retorno aos níveis do controle. Este trabalho é o primeiro a informar os níveis de resposta basal e de estresse para indicadores hematológicos e bioquímicos em dentão, representando uma base importante para o planejamento de futuras experiências com transporte e manejo dessa espécie.(AU)

Temperature affects the hypoxia tolerance of neotropical Cichlid Geophagus brasiliensis

Oxygen and temperature are the most limiting factors in aquatic environments. Several species are exposed to variations of these factors in water because of physical, chemical and biological processes. The objective of this study was to evaluate the metabolic profile and the tolerance to the hypoxia of Geophagus brasiliensis exposed to changes in temperature and oxygen availability. The fish were exposed to 20 and 90% of oxygen saturation combined with different temperatures (20°, 24° and 28° C) for 8 h. Hepatic and muscular glycogen, as well as the activities of lactate dehydrogenase (LDH), malate dehydrogenase (MDH), citrate synthase (CS) and their ratios were evaluated. Both glycogen and MDH activity showed a significant difference in the liver. While CS showed increased activity only in the heart. The increase in LDH activity in the white muscle shows the importance of the anaerobic pathway as energy source in this tissue. The MDH / LDH ratio increased in all tissues, while CS / LDH increased in the liver and decreased in the heart. Based on the results of the present study it may be concluded that this species used the anaerobic metabolism as the main strategy for hypoxia tolerance.(AU)

O oxigênio e a temperatura são os fatores mais limitantes em ambientes aquáticos. Várias espécies são expostas a variações destes fatores na água como resultado de processos físicos, químicos e biológicos. O estudo objetivou avaliar o perfil metabólico e a tolerância à hipóxia de Geophagus brasiliensis expostos a alterações na temperatura e disponibilidade de oxigênio. Os peixes foram expostos a 20% e 90% de saturação de oxigênio combinadas com diferentes temperaturas (20 ° C, 24 ° C e 28 ° C) durante 8h. Foram avaliados o glicogénio hepático e muscular, assim como as atividades das enzimas lactato desidrogenase (LDH), malato desidrogenase (MDH), citrato sintase (CS) e suas razões. Tanto o glicogênio quanto a atividade da MDH apresentaram diferença significativa no fígado. Enquanto a CS apresentou aumento de sua atividade apenas no coração. O aumento da atividade LDH no músculo branco mostra a importância da via anaeróbia como fonte de energia neste tecido. A razão MDH/LDH aumentou em todos os tecidos, enquanto CS/LDH apresentou aumento no fígado e diminuição no coração. Os resultados obtidos permitem concluir que esta espécie utilizou o metabolismo anaeróbio como principal estratégia de tolerância à hipóxia.(AU)

Acute copper toxicity in juvenile fat snook Centropomus parallelus (Teleostei: Centropomidae) in sea water

Three experiments were designed to assess the accumulation and acute toxicity of copper (Cu) in juvenile fat snook Centropomus parallelus. The first experiment was performed to determine the 96-h lethal concentration (LC50) of Cu. The second experiment was designed to assess the effects of sublethal concentrations of Cu (0.47 and 0.94 mg/L), while the third one allowed us to test the recovery capacity of fish exposed to the sublethal concentrations Cu and kept in sea water without Cu addition. The LC50 value for Cu was found to be 1.88 mg/L Cu. Fish exposed to the sublethal concentrations of Cu showed a significant accumulation of Cu in gills at 96 h respect to the control ones (0.43 µg/g Cu). No significant difference was observed in the accumulation of Cu in gills between fish exposed to 0.47 mg/L (1.09 µg/g Cu) and 0.94 mg/L (1.26 µg/g Cu). Exposure (24 and 96 h) to the sublethal concentrations of Cu tested induced DNA damage in the erythrocytes. The results show that acute exposure to sublethal concentrations induces Cu accumulation and DNA damage in fish, these effects being recovered after 240 h in sea water without Cu addition.

Três experimentos foram realizados para avaliar o acúmulo e toxicidade aguda do cobre (Cu) em juvenis de robalo-peva Centropomus parallelus. O primeiro experimento foi realizado para determinar a concentração letal (96h-CL50) de Cu. O segundo experimento foi realizado para avaliar os efeitos de concentrações subletais de Cu (0,47 e 0,94 mg/L), enquanto o terceiro permitiu testar a capacidade de recuperação dos peixes expostos a concentrações subletais do Cu e posteriormente mantidos em água do mar sem acréscimo de Cu. O valor de LC50 encontrado para o Cu foi de 1,88 mg/L. Os peixes expostos as concentrações subletais de Cu mostraram um acúmulo significativo nas brânquias em relação ao controle em 96 h de exposição (0,43 µg/g Cu). Nenhuma diferença significativa foi observada entre os peixes expostos a 0,47 mg/L de Cu (1,09 µg/g) e 0,94 mg/L de Cu (1,26 µg/g). A exposição (24 e 96 h) para as concentrações subletais de Cu induziram danos no DNA. Os resultados mostram que a exposição aguda a concentrações subletais induz o acúmulo de Cu e danos ao DNA nas brânquias dos peixes, onde estes efeitos são recuperados após 240 h em água do mar sem adição de Cu.

Effect of beta 1, 3 glucan in stress responses of the pencilfish (Nannostomus trifasciatus) during transport within the rio Negro basin

We investigated the use of beta 1,3 glucan as an imunostimulant during a transport experiment to determine the effects upon the stress response of the pencilfish (Nannostomus trifasciatus). Pencilfish were fed for seven days with different concentrations of beta 1,3 glucan: 0.0% (control); 0.01%; 0.1% and 0.5% of beta 1,3 glucan per kg of feed-1. Fish were then transported for 24 hours by boat from Barcelos to Manaus. The highest dose of beta 1,3 glucan in the food increased Na+ influx after 12 hours of transport and 0.1 and 0.5% beta 1,3 glucan maintained the flux of both ions close to zero at 24 hours. All doses of beta 1,3 glucan reduced K+ loss significantly in the beginning of the transport, but after 12 to 24 hours did not. No significant differences in whole body cortisol or survival were observed. Our results indicate that pencilfish had ionic alterations during transport from Barcelos to Manaus. The lack of significant differences in whole body cortisol and survival rate in addition to the maintenance of Na+ and K+ balance during transport reinforce the positive effects of beta 1,3 glucan immunostimulant on fish homeostasis. Therefore, we recommend its addition to food prior to transport...

O objetivo deste trabalho foi verificar se o imunoestimulante beta 1,3 glicano, adicionado à ração fornecida dias antes do transporte, pode minimizar algumas respostas de estresse do peixe lápis (Nannostomus trifasciatus) capturado na natureza. Estes peixes foram alimentados por sete dias com diferentes concentrações de beta 1,3 glicano: 0,0% (controle); 0,01 %; 0,1% e 0,5 % de beta 1,3 glicano.kg de ração-1. Após este período, as caçapas foram transportadas via barco de Barcelos para Manaus, com duração de 24 horas. Nos peixes alimentados com a maior concentração de beta 1,3 glicano na ração foi verificado aumento no influxo de Na+ após 12 horas de transporte e nos peixes alimentados com 0,1 e 0,5% de beta 1,3 glicano, o fluxo destes íons foi mantido próximo de zero no final de 24 horas de transporte. Todas as doses de beta 1,3 glicano reduziram significativamente a perda de K+ no início do transporte, mas, após 12 horas até o final do transporte houve efeito significativo no efluxo de K+. Não foram verificadas diferenças significativas entre tratamentos ou tempos de amostragem para os níveis de cortisol corpóreo. A taxa de sobrevivência não diferiu ao final do experimento. Nossos resultados indicam que o transporte entre Barcelos e Manaus promoveu alterações iônicas no peixe-lápis e a ausência de diferenças significativas no cortisol corpóreo e na taxa de sobrevivência aliada, à manutenção do equilíbrio de sódio e potássio durante o transporte, reforça o efeito positivo do imunoestimulante beta 1,3 glicano na homeostase dos peixes e sua adição à ração é recomendada...

Effect of dietary cadmium on fitness, growth, genotoxicity and accumulation in the Yellow-spotted River Turtle, Podocnemis unifilis.

The aim of this study was to expose the Yellow-spotted River Turtle, Podocnemis unifilis, to dietary cadmium (Cd) contamination. The P. unifilis were fed with a Cd contaminated diet (590 µgg(-1)) or a control diet for 30 and 60 days. After the Cd feeding period, the locomotor performance and specific growth rate were assessed. Blood samples were drawn for micronuclei analysis and tissues were collected to analyze the Cd concentration. Dietary Cd influenced the fitness of turtles at 30 days (righting time 752s), but not after 60 days (righting time 43.67s). Micronuclei in erythrocytes (12 ± 5‰) were significantly greater in contaminated turtle at 60 days. Cd accumulation is found in gut, intestine, kidney, fat, liver and blood of animals from contaminated diet group and the Cd concentration of almost all the tissues had increased following the 30-60-day feeding period. Cd does not impair animal the fitness after sixty days of dietary treatment, but it does can cause an accumulation on P. unifilis.

Sodium fluxes in tamoatá, Hoplosternum litoralle, exposed to formation water from Urucu Reserve (Amazon, Brazil).

Formation water (produce water or oil field brine) from oil and gas production usually has high concentrations of soluble salts and metals. The objective of this study was to examine the effect of formation water from Urucu Reserve, Amazon, on whole-body uptake and internal distribution of newly accumulated Na+ in juvenile tamoatá, Hoplosternum litoralle. Groups of fish were submitted to nine treatments for 3 h in 400-ml chambers: control (well water), 5% formation water, and well water with respective concentrations of 5% formation water of Ca2+, Fe, Mn, Ba2+, Fe+Ca2+, Mn+Ca2+, and Ba+Ca2+ added. Specimens of tamoatá exposed to 5% formation water presented a very high Na+ influx, probably due to the high Na+ levels in this water. Waterborne Fe and Mn stimulated Na+ influx, but Fe increased Na+ efflux, causing Na+ loss. Waterborne Mn, on the other hand, decreased Na+ efflux, reducing Na+ loss by this species. Waterborne Ca2+ also affected Na+ influx but had no significant effect on net Na+ fluxes. These results demonstrated that spilling of formation water in ion-poor Amazon rivers would dramatically disrupt osmoregulatory balance of tamoatá and probably other Amazon fish species, impairing their survival and reduce biodiversity.

Net ion fluxes in the facultative air-breather Hoplosternum littorale (tamoata) and the obligate air-breather Arapaima gigas (pirarucu) exposed to different Amazonian waters.

Fishes that live in the Amazon environment may be exposed to several kinds of water: black water (BW), acidic black water (pH 3.5) (ABW) and white water (WW), among others. The aim of the present study was to analyze net ion fluxes in the facultative air-breather Hoplosternum littorale (tamoata) and the obligate air-breather Arapaima gigas (pirarucu) exposed to different types of water. Fishes were acclimated in well water and later placed in individual chambers containing one type of water for ion flux measurements. After 4 h, the water in the chambers was replaced by a different type of water. The transfer of both species to ABW (independent of previous water exposure) increased net ion loss. Tamoatas transferred from ABW to BW or WW presented a net ion influx, but pirarucus showed only small changes on net ion efflux. These results allow us to conclude that tamoatas and pirarucus present differences in terms of ion regulation but that the general aspects of the ion flux are similar: (1) exposure to ABW led to net ion loss; (2) transfer from BW to WW or vice-versa induced only minor changes on net ion fluxes. These observations demonstrate that any osmoregulatory difficulties encountered by either species during changes between these latter two waters can be easily overcome.