Acute metabolic responses of two marine brachyuran crabs to dilute seawater: The aerobic cost of hyper regulation.

Hepatus pudibundus ("flecked box crab") is a stenohaline osmoconfomer, and restricted to marine habitats. Callinectes danae ("swimming crab Dana") lives in coastal/estuarine waters and is a weak hyper regulator. There is no consensus on which strategy is more expensive metabolically face salinity challenges: conformation with higher dependence on cell volume regulation, or hyper regulation, alleviating the need for intense cell volume regulation. Crabs were probed for their acute response to dilute seawater through exposures to salinities 35‰, 30‰, 25‰, and 20‰ for 2, 4, and 6 h. Hemolymph osmolality, lactate, and ions (chloride, sodium, magnesium, potassium) were assayed, as well as muscle water content. Water dissolved oxygen, ammonia, and pH levels were also measured. H. pudibundus conformed for osmolality and displayed increase in muscle hydration along the decrease in salinity down to 25‰, while C. danae efficiently maintained hemolymph osmo ionic stability, consumed more oxygen, acidified more the water, and released more ammonia. In 25‰, both species spent energy: H. pudibundus putatively controlling cell volume, and C. danae regulating hemolymph concentrations. In 20‰, H. pudibundus closed itself, avoiding the contact of the interface epithelia with the external environment and producing much lactate, whereas C. danae spent more energy (aerobic) in extracellular osmo ionic stability. Under these conditions, anisosmotic extracellular regulation (together with additional cell volume regulation) is more oxygen consuming than osmoconformation with a putatively more intense challenge to cell volume. The exposure to hyposalinity limits the occupation of estuarine environments by H. pudibundus in short and middle term.

Co-exposure of carbon nanotubes with carbofuran pesticide affects metabolic rate in Palaemon pandaliformis (shrimp).

Palaemon pandalirformis (shrimp) is a species widely distributed in the Brazilian coastal region and with an important economic role. In addition, this organism is considered an indicator of environmental pollution in estuaries; however, its physiological responses to toxic environmental pollutants, including pesticides and nanomaterials, are not well known, mainly, the effects of co-exposure. Thus, the purpose of this study was to evaluate the ecotoxicological effects of co-exposure between oxidized multiwalled carbon nanotubes (HNO3-MWCNT) and carbofuran pesticide on the routine metabolism of P. pandalirformis. The shrimps were exposed to different concentrations of HNO3-MWCNT (0; 10; 100; 500; 1000 µg L-1), carbofuran (0; 0.1; 1.0; 5.0; 10 µg L-1) and to co-exposure with 100 µg L-1 of HNO3-MWCNT + carbofuran (0; 0.1; 1.0; 5.0; 10 µg L-1), to evaluate the effects on metabolic rate (O2 consumption) and excretion of ammonia (NH4+NH3). Our results showed that the shrimps exposed to HNO3-MWCNT (10 µg L-1) increased the metabolic rate by 292% and the excretion of ammonia by 275%; those exposed to carbofuran (10 µg L-1) increased their metabolic rate by 162% and the excretion of ammonia by 425%; and with the co-exposure of HNO3-MWCNT + carbofuran there was also an increase in the metabolic rate by 317% and an excretion of ammonia by 433% when compared to control. These findings provides useful information toward better understanding the physiological responses of shrimps after combined exposure to nanomaterials and pesticides in aquatic environments.

Chemical Contents of Disposed Light Sticks Affect the Physiology of Rocky Crab Pachygrapsus transversus and Gray Shrimps Litopennaeus vanammei.

Light-sticks shine resulting from a chemiluminescent reaction between two components kept separate by a glass ampoule. Light-stick baits are discarded in the ocean after being used in longline fishing. The traditional Brazilian community of Costa dos Coqueiros, Brazil, uses the discarded light-sticks chemical contents found on beaches as medicine for rheumatism and mycoses. This study assessed the effects that light-sticks (chemical contents) have on Pachygrapsus transversus and Litopennaeus vanammei. Assays of metabolic changes involved rates of ammonia excretion and oxygen consumption. The EC50-60 min to juveniles and adults P. transversus were 0.0004% and 0.0046%, respectively; and L. vanammei revealed a susceptible species: EC50-60 min of 0.0006% for oxygen uptake and 0.0072% for ammonia excretion, and also was observed a hormesis effect in the ammonia excretion. Light-stick contents could promote significant metabolic changes in rocky crabs and gray shrimp. Educational actions are needed that make the population aware of and avoid the dangerous misuse of the light-sticks.

Sublethal effects of propiconazole on the metabolism of lambari Deuterodon iguape (Eigenmann 1907), a native species from Brazil.

The objective of this study was to analyze the sublethal effects of propiconazole on Deuterodon iguape, a native fish common in Brazil, which has potential for aquaculture and use as a bioindicator. The hypothesis was to test whether D. iguape has a metabolism similar to Danio rerio so that its use in bioassays may be validated. Lethal concentration (LC50) and metabolic rates were studied in fish exposed to propiconazole. Specific oxygen consumption and ammonia excretion for D. iguape and D. rerio increased by 0.01 µg L-1 and then decreased as the propiconazole concentration increased. The decrease in the averages of specific oxygen consumption at the concentration of 0.1 µg L-1 represented a reduction in the metabolic rate compared to the control of 71% for D. iguape and 40% D. rerio. For the ammonia excretion, at the same concentration, there was a reduction of 68.7% and 45.4% for D. iguape and D. rerio, respectively. When comparing ammonia excretion of the two species for each concentration of propiconazole, there was a significant difference (p < 0.05) in relation to the control and for the highest concentration (0.1 µg L-1). As for specific oxygen consumption, there was a statistically significant difference only for the concentration of 0.1 µg L-1. D. iguape proved to be a good and useful bioindicator for ichthyologists or ecologists in studies of moderate pesticide contamination in freshwater aquatic environments, as its metabolic response was similar to D. rerio.

Effect of Fluoxetine Hydrochloride on Routine Metabolism of Lambari (Deuterodon iguape, Eigenmann, 1907) and Phantom Shrimp (Palaemon pandaliformis, Stimpson, 1871)

HIGHLIGHTS Fluoxetine increases the metabolic rate and excretion of ammonia in both species. O:N ratio in fish showed higher values in the highest concentrations of fluoxetine. The LC50 - 96 hour values of Palaemon pandaliformis represented greater toxicity. Both species are a good biological model for fluoxetine exposure studies.

Abstract Fluoxetine is an emerging pollutant that acts as a selective serotonin reuptake inhibitor (SSRI) and being a hydrolytic molecule that is photolytically stable and accumulaties in biological tissues, its disposal in the aquatic environment can interfere with the physiology of fish and shrimp. Thus, the objective of this study was to analyze the effects of fluoxetine on routine metabolism (metabolic rate, specific ammonia excretion and O:N ratio) of Deuterodon iguape and Palaemon pandaliformis. For this, five groups of each species, were exposed to different concentrations of fluoxetine for 24 hours (D. iguape) and 2 hours (P. pandaliformis). The results demonstrated that in D. iguape exposure to fluoxetine significantly increased both the metabolic rate by 75%, 85%, 55% and 50% for concentrations of 0.05; 0.1; 0.5 and 1.0 mgL-1, respectively, and the specific ammonia excretion by 40%, 48% and 20% for concentrations of 0.05; 0.1 and 0.5 mgL-1, respectively, when compared with their control. The O:N ratio was statistically greater in concentrations of 0.5 and 1.0 mgL-1. Concerning P. pandaliformis, exposure to fluoxetine increased metabolic rate at concentrations 30.0 and 60.0 µgL-1, and also increased specific ammonia excretion at concentrations 10.0, 30.0 and 60.0 µgL-1, when compared with the control group. It was concluded that exposure to fluoxetine increases the routine metabolism of both species and that at the concentration 1.0 mgL-1, Deuterodon iguape required different energy substrates.

Metabolic effects in the freshwater fish Geophagus iporangensis in response to single and combined exposure to graphene oxide and trace elements.

Graphene oxide (GO) is part of a new set of nanomaterials with particular characteristics related to its nanoscale size. Due to this feature, it presents high reactivity and other contaminants present in the environment could bind to them and affect its intrinsic toxicity. The metabolic effects of such nanomaterials and their combination with two common pollutants, zinc and cadmium, on the freshwater fish Geophagus iporangensis are analyzed. Moreover, metabolic rate and ammonia excretion were used as bioindicators to measure metabolic changes. Fishes were exposed for 24 h in filtered tap water to different concentrations of GO (0.5; 1.0; 2.0 and 4.0 mg L-1), Zn (0.5; 1.0; 2.0; 4.0 and 10.0 mg L-1) and Cd (0.1; 0.5; 1.0; 2.0 and 4.0 mg L-1). Combined effects were verified using the same concentrations of trace elements added to 1.0 mg L-1 of GO. Exposure to GO and Cd resulted in a decrease of metabolic rate in G. iporangensis, by about 30% compared to control means, in the highest concentration tested (4.0 mg L-1). However, zinc exposure in the highest concentration (10 mg L-1) raised metabolic rate to around three times that of the control group. Ammonia excretion was not affected by exposure to GO and Cd. In contrast, exposure to Zn at 10 mg L-1 raised the rate to around 47%. The combined exposure of GO and Zn intensified the effects of the trace element, inducing responses in both biomarkers at lower concentrations and demonstrating that the interaction between elements increases zinc's effects. The combination Cd + GO only affects metabolic rate. Thus, this metabolic rate alone reveals that combined exposure potentiates effects of trace elements on fish metabolism.

Co-exposure of graphene oxide with trace elements: Effects on acute ecotoxicity and routine metabolism in Palaemon pandaliformis (shrimp).

Graphene oxide (GO) has been evaluated for application in environmental remediation and pollution control strategies. However, the side effects caused by the interactions of GO with classical pollutants in aquatic environments are still largely unknown. In this work, the ecotoxicological effects of GO, cadmium, zinc and the interactions between GO and these trace elements (co-exposure) were evaluated through acute toxicity tests and routine metabolism (i.e., oxygen consumption and ammonia excretion) in Palaemon pandaliformis (shrimp). After 96 h of exposure, GO did not present acute ecotoxicity at concentrations up to 5.0 mg L-1. However, the association of GO with Cd or Zn increased the toxicity of these trace elements as demonstrated by the decrease in LC50 values. The 96 h LC50 of Cd associated with GO was 1.7 times less than the 96 h LC50 of Cd alone. Similarly, the 96 h LC50 of Zn associated with GO was 1.8 times less than the 96 h LC50 of Zn alone. Additionally, the co-exposure of GO with trace elements impaired the routine metabolism of P. pandaliformis. Finally, the GO potentiated the ecotoxicological effects of Cd and Zn in the shrimp model. Future research on this emerging nanomaterial should focus on its use and disposal in aquatic ecosystems.

Decreased Metabolic Rate in the Mole Crabs, Emerita analoga, Infected with the Acanthocephalan Profilicollis altmani.

The relationship between a parasite and its host will have an energy cost for the host at some point; however, this basic hypothesis has seldom been evaluated. Using Emerita analoga as a model species, we investigated the aerobic metabolism, ammonia excretion rate, and locomotor performance patterns of crabs both uninfected and infected with the acanthocephalan Profilicollis altmani. Our results show that infected Emerita had a lower metabolic rate compared to uninfected ones. Whether or not this decrease is a result of the pathology of the parasite infection or due to manipulation of the host by the parasite is still unknown. We discuss the importance of using anaerobic and aerobic metabolism and more-complex scenarios in order to understand the effects on host fitness and not only on the immediate response of the host.

Effects of multiwalled carbon nanotubes and carbofuran on metabolism in Astyanax ribeirae, a native species.

The study of the toxic effect of carbofuran and multiwalled carbon nanotubes (MWCNTs) on Astyanax ribeirae metabolism is of paramount importance due to the increasing use of this pesticide in agriculture and in the production of nanotubes within the material industry. This study aimed to evaluate the effects of carbofuran, MWCNT, and the combination of these compounds on specific oxygen consumption and excretion of ammonia in A. ribeirae. Therefore, 65 fish were divided into three groups of treatments at varying concentrations: carbofuran (0.01, 0.05, 0.1, and 0.5 mg/L), MWCNT (0.1, 0.25, 0.5, and 1.0 mg/L), and 0.5 mg/L of MWCNT added to carbofuran concentrations (0.01, 0.05, 0.1, and 0.5 mg/L). The average specific oxygen consumption in the groups exposed to carbofuran, compared to the control, increased 73.49% at the 0.01 mg/L concentration and decreased 63.86% and 91.57% with treatments of 0.1 and 0.5 mg/L, respectively. For groups exposed to the MWCNT, there was an 83.91% drop with the 1.0 mg/L treatment, and the carbofuran + MWCNT groups recorded a decrease of 71.09%, 92.77%, and 93.98% at concentrations of 0.05, 0.1, and 0.5 mg/L, respectively. In relation to specific ammonia excretion, in groups exposed to carbofuran compared to the control, there was an increase of 134.37% and 200% with the 0.1 and 0.5 mg/L treatments, respectively. The group exposed to carbofuran + MWCNT experienced a decrease of 60% and 80% with treatments of 0.1 mg/L carbofuran + 0.5 mg/L MWCNT and 0.5 mg/L carbofuran + 0.5 mg/L MWCNT, respectively. Therefore, it was concluded that carbofuran + MWCNT interact, increasing the effects in Astyanax sp.

Physiological protective action of dissolved organic carbon on ion regulation and nitrogenous waste excretion of zebrafish (Danio rerio) exposed to low pH in ion-poor water.

Dissolved organic carbon (DOC) represents a heterogeneous group of naturally-occurring molecules in aquatic environments, and recent studies have evidenced that optically dark DOCs can exert some positive effects on ionoregulatory homeostasis of aquatic organisms in acidic waters. We investigated the effects of Luther Marsh DOC, a dark allochthonous DOC, on ion regulation and N-waste excretion of zebrafish acutely exposed to either neutral or low pH in ion-poor water. In the first experiment, simultaneous exposure to pH 4.0 and DOC greatly attenuated the stimulation of Na+ diffusive losses (J outNa ), and prevented the blockade of Na+ uptake (J inNa ) seen in zebrafish exposed to pH 4.0 alone, resulting in much smaller disturbances in Na+ net losses (J netNa ). DOC also attenuated the stimulation of net Cl- losses (J netCl ) and ammonia excretion (J netAmm ) during acidic challenge. In the second experiment, zebrafish acclimated to DOC displayed similar regulation of J inNa and J outNa , and, therefore, reduced J netNa at pH 4.0, effects which persisted even when DOC was no longer present. Protective effects of prior acclimation to DOC on J netCl and J netAmm at pH 4.0 also occurred, but were less marked than those on Na+ balance. Urea fluxes were unaffected by the experimental treatments. Overall, these effects were clearly beneficial to the ionoregulatory homeostasis of zebrafish at low pH, and were quite similar to those seen in a recent parallel study using darker DOC from the upper Rio Negro. This suggests that dark allochthonous DOCs share some chemical properties that render fish tolerant to ionoregulatory disturbances during acidic challenge.

Titanium dioxide nanoparticles alter routine metabolism and cause histopathological alterations in Oreochromis niloticus / Efeito de nanopartículas de dióxido de titânio sobre Oreochromis niloticus: metabolismo de rotina e alteração histológica

Titanium Dioxide Nanoparticles (TiO2NPs) could cause alterations in exposed aquatic species, in terms of oxygen consumption, ammonia excretion and tissues functionality therefore, the aim of the present study is to evaluate the effects of acute exposure to different concentrations of TiO2NPs (0.1, 0.5, 1.0 and 2.5 mgL-1) on routine metabolism (oxygen consumption and ammonia excretion) and histological parameters (branchial and hepatic) in Oreochromis niloticus. After 24 hours, we observed an increase in oxygen consumption of 2.36 and 3.23 times in groups exposed to 1.0 and 2.5 mgL-1 of TiO2 NPs respectively, as well as an increase in ammonia excretion of 3.54, 4.0 and 4.82 times higher in groups exposed to 0.5, 1.0 and 2.5 mgL-1 of TiO2 NPs respectively, compared to the control group. Histological analysis showed, after 72 hours, moderate to severe alterations in both gills and liver of TiO2 exposed fish at concentrations 1.0 and 2.5 mgL-1, the severity and occurrence of the alteration observed was grade 3 (severe and extensive pathological alterations). We concluded that waterborne exposure of Nile tilapia to TiO2 NPs caused alteration in routine metabolism and histological parameters in a dose-dependent manner.(AU)

Nanoparticulas de Dióxido de Titânio (TiO2NPs) podem causar alterações nas espécies aquáticas expostas, em termos de consumo de oxigênio, excreção de amônia e funcionalidade de tecidos, portanto, o objetivo do presente estudo é avaliar os efeitos da exposição aguda a diferentes concentrações de TiO2NPs (0,1, 0,5, 1,0 e 2,5 mgL-1) sobre o metabolismo de rotina (consumo de oxigênio e excreção de amônia) e parâmetros histológicos (branquiais e hepáticos) em Oreochromis niloticus. Após 24 horas, observamos um aumento no consumo de oxigênio de 2,36 e 3,23 vezes em grupos expostos a 1,0 e 2,5 mgL-1 de TiO2NPs respectivamente, bem como um aumento na excreção de amônia de 3,54, 4,0 e 4,82 vezes maior nos grupos expostos a 0,5, 1,0 e 2,5 mgL-1 de TiO2NPs respectivamente, em comparação com o grupo controle. A análise histológica mostrou, após 72 horas, alterações moderadas a severas tanto nas brânquias quanto no fígado de peixes expostos a TiO2NPs em concentrações de 1,0 e 2,5 mgL-1, a gravidade e a ocorrência da alteração observada foram de grau 3 (alterações patológicas graves e extensas). Concluímos que a exposição à TiO2NPs da tilápia do Nilo causaram alteração no metabolismo de rotina e nos parâmetros histológicos de uma maneira dose-dependente.(AU)

Titanium dioxide nanoparticles alter routine metabolism and cause histopathological alterations in Oreochromis niloticus / Efeito de nanopartículas de dióxido de titânio sobre Oreochromis niloticus: metabolismo de rotina e alteração histológica

Titanium Dioxide Nanoparticles (TiO2NPs) could cause alterations in exposed aquatic species, in terms of oxygen consumption, ammonia excretion and tissues functionality therefore, the aim of the present study is to evaluate the effects of acute exposure to different concentrations of TiO2NPs (0.1, 0.5, 1.0 and 2.5 mgL-1) on routine metabolism (oxygen consumption and ammonia excretion) and histological parameters (branchial and hepatic) in Oreochromis niloticus. After 24 hours, we observed an increase in oxygen consumption of 2.36 and 3.23 times in groups exposed to 1.0 and 2.5 mgL-1 of TiO2 NPs respectively, as well as an increase in ammonia excretion of 3.54, 4.0 and 4.82 times higher in groups exposed to 0.5, 1.0 and 2.5 mgL-1 of TiO2 NPs respectively, compared to the control group. Histological analysis showed, after 72 hours, moderate to severe alterations in both gills and liver of TiO2 exposed fish at concentrations 1.0 and 2.5 mgL-1, the severity and occurrence of the alteration observed was grade 3 (severe and extensive pathological alterations). We concluded that waterborne exposure of Nile tilapia to TiO2 NPs caused alteration in routine metabolism and histological parameters in a dose-dependent manner.

Nanoparticulas de Dióxido de Titânio (TiO2NPs) podem causar alterações nas espécies aquáticas expostas, em termos de consumo de oxigênio, excreção de amônia e funcionalidade de tecidos, portanto, o objetivo do presente estudo é avaliar os efeitos da exposição aguda a diferentes concentrações de TiO2NPs (0,1, 0,5, 1,0 e 2,5 mgL-1) sobre o metabolismo de rotina (consumo de oxigênio e excreção de amônia) e parâmetros histológicos (branquiais e hepáticos) em Oreochromis niloticus. Após 24 horas, observamos um aumento no consumo de oxigênio de 2,36 e 3,23 vezes em grupos expostos a 1,0 e 2,5 mgL-1 de TiO2NPs respectivamente, bem como um aumento na excreção de amônia de 3,54, 4,0 e 4,82 vezes maior nos grupos expostos a 0,5, 1,0 e 2,5 mgL-1 de TiO2NPs respectivamente, em comparação com o grupo controle. A análise histológica mostrou, após 72 horas, alterações moderadas a severas tanto nas brânquias quanto no fígado de peixes expostos a TiO2NPs em concentrações de 1,0 e 2,5 mgL-1, a gravidade e a ocorrência da alteração observada foram de grau 3 (alterações patológicas graves e extensas). Concluímos que a exposição à TiO2NPs da tilápia do Nilo causaram alteração no metabolismo de rotina e nos parâmetros histológicos de uma maneira dose-dependente.

Assessment of acute toxicity of carbofuran in Macrobrachium olfersii (Wiegmann, 1836) at different temperature levels.

Carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate; C12H15NO3) is one of the most toxic carbamate pesticides. For acute toxicity of carbofuran, juveniles of Macrobrachium olfersii were exposed to different concentrations of carbofuran using the static renewal method at different temperature levels (15, 20 and 25°C) at pH 7.0. The main purpose of the present study was to detect the acute toxicity of carbofuran to M. olfersii and investigate its effects on oxygen consumption and ammonium excretion; these tests have not been carried out in this species before. First, the acute toxicity - median lethal concentration - of carbofuran to M. olfersii for 24, 48, 72 and 96 h was examined, which resulted in the following values: 1.64, 1.22, 0.86 and 0.42 mg L(-1), respectively. Furthermore, we also found that carbofuran caused an inhibition in oxygen consumption of 60.6, 65.3 and 66.2% with respect to the control. In addition, after separate exposures to carbofuran, elevations in ammonium excretion were more than 500% with respect to the control.

Ammonia excretion and expression of transport proteins in the gills and skin of the intertidal fish Lipophrys pholis.

Intertidal pools are intensely challenging environments, due to rapid and extreme fluctuations in water conditions during the tidal cycle. Emersion is another challenge intertidal fishes may face. Mechanisms of ammonia excretion and ion regulation were studied in the resident amphibious blennid Lipophrys pholis. The ammonia transporters Rhcg1 and Rhcg2 were cloned and characterized. Fish were challenged for 24h to 1) emersion, 2) fresh water (FW), and 3) high environmental ammonia (HEA; 1mM NH4Cl), or 4) ammonia loading (1.5µmol/g NH4HCO3). When air exposed, L. pholis maintained aquatic ammonia excretion rates (JAmm) while branchial Na(+)/K(+)-ATPase (NKA) activity increased, but no changes at the protein or mRNA levels of transporters were noted. In FW, JAmm decreased and osmotic problems were encountered. Skin NKA activity decreased, branchial Rhcg2, and skin Rhcg1 and Rhcg2 increased. Exposure to HEA only increased branchial Rhcg2 levels. Although internal ammonia loading only led to a modest non-significant increase in JAmm, skin NKA (activity and α-subunit), carbonic anhydrase protein levels, and branchial Rhcg1 levels increased. In summary, variable responses were observed involving both gill and skin but given the instability of its habitat, the constitutive expression of transporters is likely also of importance.