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Mykiss
Kinds of Mykiss Terms modified by Mykiss Selected AbstractsPacific Salmon Extinctions: Quantifying Lost and Remaining DiversityCONSERVATION BIOLOGY, Issue 4 2007RICHARD G. GUSTAFSON biodiversidad; diversidad de salmones; extinción de poblaciones; historia de vida de salmones Abstract:,Widespread population extirpations and the consequent loss of ecological, genetic, and life-history diversity can lead to extinction of evolutionarily significant units (ESUs) and species. We attempted to systematically enumerate extinct Pacific salmon populations and characterize lost ecological, life history, and genetic diversity types among six species of Pacific salmon (Chinook [Oncorhynchus tshawytscha], sockeye [O. nerka], coho [O. kisutch], chum [O. keta], and pink salmon [O. gorbuscha] and steelhead trout [O. mykiss]) from the western contiguous United States. We estimated that, collectively, 29% of nearly 1400 historical populations of these six species have been lost from the Pacific Northwest and California since Euro-American contact. Across all species there was a highly significant difference in the proportion of population extinctions between coastal (0.14 extinct) and interior (0.55 extinct) regions. Sockeye salmon (which typically rely on lacustrine habitats for rearing) and stream-maturing Chinook salmon (which stay in freshwater for many months prior to spawning) had significantly higher proportional population losses than other species and maturation types. Aggregate losses of major ecological, life-history, and genetic biodiversity components across all species were estimated at 33%, 15%, and 27%, respectively. Collectively, we believe these population extirpations represent a loss of between 16% and 30% of all historical ESUs in the study area. On the other hand, over two-thirds of historical Pacific salmon populations in this area persist, and considerable diversity remains at all scales. Because over one-third of the remaining populations belong to threatened or endangered species listed under the U.S. Endangered Species Act, it is apparent that a critical juncture has been reached in efforts to preserve what remains of Pacific salmon diversity. It is also evident that persistence of existing, and evolution of future, diversity will depend on the ability of Pacific salmon to adapt to anthropogenically altered habitats. Resumen:,Las extirpaciones generalizadas de poblaciones y la consecuente pérdida de diversidad ecológica, genética y de historia natural puede llevar a la extinción de unidades evolutivamente significativas (UES) y especies. Intentamos enumerar sistemáticamente a las poblaciones extintas de salmón del Pacífico y caracterizar a los tipos de diversidad ecológica, de historia natural y genética de seis especies de salmón del Pacífico Oncorhynchus tshawytscha, O. nerka, O. kisutch, O. keta, y O. gorbuscha; y trucha O. mykiss en el occidente de Estados Unidos. Estimamos que, colectivamente, se ha perdido a 29% de casi 1400 poblaciones históricas de estas seis especies en el Pacífico Noroeste y California desde la colonización europea. En todas las especies hubo una diferencia altamente significativa en la proporción de extinción de poblaciones entre regiones costeras (0.14 extintas) e interiores (0.55 extintas). O. nerka (que típicamente cría en hábitats lacustres) y O. tshawytscha (que permanece en agua dulce por muchos meses antes del desove) tuvieron pérdidas poblacionales significativamente mayores que las otras especies y tipos de maduración. Se estimó que las pérdidas agregadas de componentes mayores de la biodiversidad ecológica, de historia natural y genética en todas las especies fueron de 33%, 15% y 27%, respectivamente. Colectivamente, consideramos que estas extirpaciones de poblaciones representan una pérdida entre 16% y 30% de todas las UES históricas en el área de estudio. Por otro lado, más de dos tercios de las poblaciones históricas de salmón del Pacífico persisten en esta área, y aun hay considerable diversidad en todas las escalas. Debido a que más de un tercio de las poblaciones restantes pertenecen a especies enlistadas como amenazadas o en peligro en el Acta de Especies en Peligro de E. U. A., es evidente que se ha llegado a una disyuntiva crítica en los esfuerzos para preservar lo que queda de la diversidad de salmón del Pacífico. También es evidente que la persistencia de la diversidad existente, y su futura evolución, dependerá de la habilidad del salmón del Pacífico para adaptarse a hábitats alterados antropogénicamente. [source] Interspecific Effects of Artifically Propagated Fish: an Additional Conservation Risk for SalmonCONSERVATION BIOLOGY, Issue 6 2002Phillip S. Levin We tested the hypothesis that hatchery-reared steelhead salmon ( Oncorhynchus mykiss) released into the Snake River Basin negatively affect the survival of wild Snake River steelhead and chinook ( O. tshawytscha) salmon. Because climatic conditions can influence salmon survival, we included an index of the El Niño,Southern Oscillation ( ENSO) as a covariate in our analyses. Based on time series of hatchery releases and rates of smolt-to-adult survival, we demonstrate that the survival of wild chinook salmon is negatively associated with hatchery releases of steelhead. The state of the ( ENSO) did not affect the strength of this relationship. We observed no relationship between survival of wild steelhead and steelhead hatchery releases. Our results suggest that industrial-scale production of hatchery fish may hinder the recovery of some threatened salmonids and that the potential interspecific impact of hatcheries must be considered as agencies begin the process of hatchery reform. Resumen: Por más de 120 años, las granjas han liberado números enormes de salmones del Pacífico para compensar las numerosas agresiones humanos a sus poblaciones, sin embargo, los impactos ecológicos de este esfuerzo masivo son poco entendidos. Evaluamos la hipótesis de que la trucha cabeza de acero ( Oncorhynchus mykiss) criada en granjas y liberada en la cuenca del Río Snake afecta negativamente la supervivencia de truchas cabeza de acero y salmones chinook ( O. tshawytscha) silvestres. Puesto que las condiciones climáticas pueden influir sobre la supervivencia del salmón, incluimos un índice de la Oscilación del Niño del Sur como covariable del análisis. En base a series de tiempo de las liberaciones de las granjas y las tasas de supervivencia hasta adulto de peces migrantes al mar, demostramos que la supervivencia del salmón chinook silvestre está negativamente correlacionada con las liberaciones de truchas cabeza de acero de las granjas. El estado de la Oscilación del Niño del Sur no afectó el grado de correlación. No observamos relación alguna entre la supervivencia de las truchas silvestres y las liberaciones de las granjas. Nuestros resultados sugieren que la producción a escala industrial de peces de granja puede obstaculizar la recuperación de algunos salmónidos amenazados y que el impacto interespecífico potencial de las granjas debería ser considerado en cuanto las agencias inicien el proceso de reforma de las granjas. [source] Brain distribution of myosin Va in rainbow trout Oncorhynchus mykissACTA ZOOLOGICA, Issue 1 2008Kátia Gisele Oliveira Rancura Abstract This study presents data on myosin Va localization in the central nervous system of rainbow trout. We demonstrate, via immunoblots and immunocytochemistry, the expression of myosin Va in several neuronal populations of forebrain, midbrain, hindbrain and spinal cord. The neuronal populations that express myosin Va in trout constitute a very diverse group that do not seem to have many specific similarities such as neurotransmitters used, cellular size or length of their processes. The intensity of the immunoreactivity and the number of immunoreactive cells differ from region to region. Although there is a broad distribution of myosin Va, it is not present in all neuronal populations. This result is in agreement with a previous report, which indicated that myosin Va is approximately as abundant as conventional myosin II and kinesin, and it is broadly involved in neuronal motility events such as axoplasmatic transport. Furthermore, this distribution pattern is in accordance with what was shown in rats and mice; it indicates phylogenetic maintenance of the myosin Va main functions. [source] Effects of radio-transmitter antenna length on swimming performance of juvenile rainbow troutECOLOGY OF FRESHWATER FISH, Issue 4 2004K. J. Murchie Abstract,,, Technological advances have lead to the production of micro radio-transmitters capable of being implanted in fish as small as c. 5 g. Although the actual tags are small, transmitters are equipped with long antennas that can increase drag and tangle in debris. We examined the effects of radio-transmitter antenna length on the swimming performance of juvenile rainbow trout, Oncorhynchus mykiss, (N = 156, mean mass = 34 g, mean fork length = 148 mm). Although we tested a variety of different antenna lengths up to a maximum of 300 mm, only the longest antenna significantly impaired swimming performance relative to control fish (P < 0.001). There was no difference in swimming performance between the sham (surgery, but no transmitter) and the control fish (handled, but no surgery), suggesting that the surgical procedure itself did not negatively affect the fish. Regression analysis, however, indicated that there was a significant decrease in swimming performance associated with increased antenna length (R2 = 0.11, P < 0.001). In addition, when held in laboratory tanks, fish with the three longest antennas (150, 225 and 300 mm) frequently became entangled with the standpipe. We suggest that researchers, under the guidance of the tag manufacturer, trim antennas to the shortest possible length required to detect fish in their specific study area. Antenna length is clearly an important issue for small fish, especially for species that inhabit complex habitats where antennas may become entangled, and where fish must attain speeds near limits of their swimming capacity. Resumen 1. Los avances tecnológicos han llevado a producir micro radio-trasmisores capaces de ser implantados en peces de muy pequeño tamaño (,5 g). Aunque las marcas actuales son pequeñas, los trasmisores están equipados con antenas largas que pueden llegar a enredarse en los restos de vegetación. Examinamos los efectos de la longitud de la antena sobre la rutina natatoria de juveniles de Oncorhynchus mykiss (n = 156, peso medio = 34 g, longitud furcal media = 148 mm). 2. Aunque analizamos varias longitudes de antena, hasta 300 mm, solamente las de mayor longitud alteraron la rutina natatoria en relación a los peces control (P < 0.001). No hubo diferencia en la rutina natatoria entre individuos bajo cirugía pero sin trasmisores respecto de los individuos control (manipulados pero sin cirugía) lo que sugiere que los procedimientos de cirugía no afectaron negativamente a los peces. Sin embargo, análisis de regresión indicaron un declive significativo en la rutina natatoria asociado a la longitud de la antena (R2 = 0.11, P < 0.001). Además, al ser mantenidos en tanques, los individuos con las tres antenas mas largas (150, 225, y 300 mm) frecuentemente se enredaron con las tuberías. 3. Sugerimos a los investigadores que, bajo la dirección de los productores de marcas y antenas, consideren el uso de las antenas más pequeñas que permitan detectar a los peces en sus respectivas áreas de estudio. La longitud de la antena es una cuestión importante para los pequeños peces, especialmente para especies en hábitats complejos donde las antenas pueden llegar a enredarse y donde los peces pueden alcanzar velocidades casi al limite de su capacidad natatoria. [source] Comparative study on sensitivity of higher plants and fish to heavy fuel oilENVIRONMENTAL TOXICOLOGY, Issue 4 2004N. Kazlauskien Abstract Laboratory tests were conducted on higher plants [garden cress (Lepidium sativum), great duckweed (Spirodela polyrrhiza), and Tradescantia clone BNL 02] and fish [rainbow trout (Oncorhynchus mykiss) at all stages of development: eggs, larvae and adults] to estimate their sensitivity to heavy fuel oil (HFO). A number of biological indices (survival, growth, and physiological and morphological parameters) as well as the genotoxic impact (Tradescantia) of HFO was evaluated by acute and chronic toxicity tests. Fish were found to be more sensitive to the toxic effect of HFO than were higher plants. EC50 values obtained for higher plants ranged from 8.7 g/L (L. sativum) to 19.8 g/L (Tradescantia), and maximum-acceptable-toxicant concentration (MATC) values ranged from 0.1 to 1.0 g/L of total HFO for L. sativum and Tradescantia, respectively. The 96-h LC50 values ranged from 0.33 g/L, for larvae, to 2.97 g/L, for adult fish, and the MATC value for fish was found to be equal to 0.0042 g/L of total HFO. To evaluate and predict the ecological risk of the overall effects of oil spills, studies should be performed using a set of acute and chronic bioassays that include test species of different phylogenetic levels with the most sensitive morphological, physiological, and genotoxic indices. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 449,451, 2004 [source] Relationship between biotic ligand model-based water quality criteria and avoidance and olfactory responses to copper by fishENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2010Joseph S. Meyer Abstract The U.S. Environmental Protection Agency's (U.S. EPA) water quality criteria for Cu were tested to determine whether they protect fish against neurophysiological impairment. From published studies with rainbow trout (Oncorhynchus mykiss), Chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), and fathead minnows (Pimephales promelas), 20% inhibition concentrations (IC20s) were calculated for avoidance of Cu-containing water and for impairment of electroencephalogram (EEG) and electro-olfactogram (EOG) responses to natural odorants in Cu-containing water. Additionally, a Cu-olfactory biotic ligand model (BLM) that fits the coho salmon EOG data was parameterized by changing the sensitivity parameter in the ionoregulatory-based BLM. The IC20s calculated from reported Cu avoidance, EEG, and EOG data and IC20s predicted by the olfactory BLM were compared with acute and chronic Cu criteria calculated using U.S. EPA's BLM 2007 or hardness-adjustment equations. The BLM-based chronic criteria were protective in all 16 exposure water,species combinations used in avoidance and olfaction experiments. Additionally, the BLM-based acute criteria were protective in all 11 exposure water,species combinations in which comparisons could be made with olfactory BLM-predicted IC20s but not in two of the 16 exposure water,species combinations in which comparisons could be made with the reported IC20s (which were ,8% lower than but did not differ significantly from the BLM-based acute criteria; p,>,0.05). In effect, the olfactory BLM factored out the relatively high variability in the reported IC20s. It is concluded that the U.S. EPA's BLM-based water quality criteria for Cu protect against these types of neurophysiological impairment in the six species,endpoint combinations analyzed in this paper. However, the U.S. EPA's hardness-based criteria for Cu sometimes were considerably underprotective and sometimes were much less protective than the BLM-based criteria. Environ. Toxicol. Chem. 2010;29:2096,2103. © 2010 SETAC [source] Influence of deltamethrin on nonspecific cellular and humoral defense mechanisms in rainbow trout (Oncorhynchus mykiss),ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2010Andrzej K. Siwicki Abstract The influence of deltamethrin on the innate immunity in rainbow trout was examined. Fish were immersed in deltamethrin at doses of 1, 2, and 4,µg/L for 30 min. The results showed that deltamethrin at doses of 2 and 4,µg/L decreased phagocytic activity of spleen macrophages and proliferative response of pronephros lymphocytes at days 1, 2, and 5 after immersion. Deltamethrin at these doses decreased the lysozyme activity, total protein, and immunoglobulin levels in serum. The greatest immunosuppressive influence of deltamethrin at dose 4,µg/L was observed at the end of the study. Environ. Toxicol. Chem. 2010;29:489,491. © 2009 SETAC [source] Pharmaceutical industry effluent diluted 1:500 affects global gene expression, cytochrome P450 1A activity, and plasma phosphate in fish,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2009Lina Gunnarsson Abstract Patancheru, near Hyderabad, India, is a major production site for the global bulk drug market. Approximately 90 manufacturers send their wastewater to a common treatment plant in Patancheru. Extraordinary high levels of a wide range of pharmaceuticals have recently been demonstrated in the treated effluent. As little as 0.2% of this effluent can strongly reduce the growth rate of tadpoles, but the underlying mechanisms of toxicity are not known. To begin addressing how the effluent affects aquatic vertebrates, rainbow trout (Oncorhynchus mykiss) were exposed to 0.2% effluent for 5 d. Several physiological endpoints, together with effects on global hepatic gene expression patterns, were analyzed. The exposed fish showed both an induction of hepatic cytochrome P450 1A (CYP1A) gene expression, as well as enzyme activity. Clinical blood chemistry analyses revealed an increase in plasma phosphate levels, which in humans indicates impaired kidney function. Several oxidative stress-related genes were induced in the livers; however, no significant changes in antioxidant enzyme activities or in the hepatic glutathione levels were found. Furthermore, estrogen-regulated genes were slightly up-regulated following exposure, and moderate levels of estriol were detected in the effluent. The present study identifies changes in gene expression triggered by exposure to a high dilution of the effluent, supporting the hypothesis that these fish are responding to chemical exposure. The pattern of regulated genes may contribute to the identification of mechanisms of sublethal toxicity, as well as illuminate possible causative agents. [source] Dietary uptake models used for modeling the bioaccumulation of organic contaminants in fish,,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2008M. Craig Barber Abstract Numerous models have been developed to predict the bioaccumulation of organic chemicals in fish. Although chemical dietary uptake can be modeled using assimilation efficiencies, bioaccumulation models fall into two distinct groups. The first group implicitly assumes that assimilation efficiencies describe the net chemical exchanges between fish and their food. These models describe chemical elimination as a lumped process that is independent of the fish's egestion rate or as a process that does not require an explicit fecal excretion term. The second group, however, explicitly assumes that assimilation efficiencies describe only actual chemical uptake and formulates chemical fecal and gill excretion as distinct, thermodynamically driven processes. After reviewing the derivations and assumptions of the algorithms that have been used to describe chemical dietary uptake of fish, their application, as implemented in 16 published bioaccumulation models, is analyzed for largemouth bass (Micropterus salmoides), walleye (Sander vitreus = Stizostedion vitreum), and rainbow trout (Oncorhynchus mykiss) that bioaccumulate an unspecified, poorly metabolized, hydrophobic chemical possessing a log KOW of 6.5 (i.e., a chemical similar to a pentachlorobiphenyl). [source] Tracing salmon-derived nutrients and contaminants in freshwater food webs across a pronounced spawner density gradientENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2007Irene Gregory-Eaves Abstract Many have demonstrated that anadromous Pacific salmon are significant vectors of nutrients from the ocean to freshwaters. Recently, however, it has been recognized that salmon spawners also input significant quantities of contaminants. The objectives of this paper are to delineate the extent to which salmon-derived nutrients are integrated into the freshwater food web using ,15N and ,13C and to assess the influence of the salmon pathway in the accumulation of contaminants in rainbow trout (Oncorhynchus mykiss). We found that the ,15N and ,13C of food web components were related positively and significantly to sockeye salmon (Oncorhynchus nerka) spawner density. Contaminant concentrations in rainbow trout also positively and significantly were related to sockeye salmon spawner density. These data suggest that the anadromous salmon nutrient and contaminant pathways are related and significantly impact the contaminant burden of resident fish. [source] Risk assessment of Magnacide® H herbicide at Río Colorado irrigation channels (Argentina). tier 3: Studies on native speciesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2007Andrés Venturino Abstract We evaluated the potential environmental risk of the herbicide Magnacide® (Baker Petrolite, TX, USA) using native species from Argentina, representing the ecosystem at the Irrigation Corporation (CORFO) channels at the Colorado River mouth, Buenos Aires, Argentina. Six species including fish, toads, snails, crustaceans, and insects were selected to perform studies on acute toxicity and repeated exposure effects. Magnacide H susceptibility ranking was Bufo arenarum (lethal concentration 50 [LC50] = 0.023 mg/L), Onchorhynchus mykiss (LC50 = 0.038 mg/L), Heleobia parchappii (LC50 = 0.21 mg/L), Hyalella curvispina (LC50 = 0.24 mg/L), Simulium spp. (LC50 = 0.60 mg/L), and Chironomus spp. (LC50 = 2.83 mg/L). The risk limit of 10th percentile (0.013 mg/L) determined by probit analysis on sensitivity distribution was similar to the one calculated from literature data. Risk assessment based on field application data suggested lethal exposures for more than 70 to 90% of the species up to 20 km downstream from the application point. Repeated exposures to Magnacide H of amphibian larvae at the lowest-observed-effect concentration caused some effects during the first exposure, but without cumulative effects. Amphipods were insensitive to repeated exposures, showing no cumulative effects. Whether short-term exposures may result in long-term sublethal effects on the organism's life history was not addressed by these laboratory tests. In conclusion, tier 3 studies indicate that Magnacide H application schedule is extremely toxic for most native species at CORFO,Río Colorado channels, representing a high potential risk in the environment. The real environmental impact must be addressed by field studies at tier 4 giving more information on population effects and communities. [source] Dynamics of 17,-Ethynylestradiol exposure in rainbow trout (Oncorhynchus mykiss): Absorption, tissue distribution, and hepatic gene expression patternENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2006Ann D. Skillman Abstract 17,-Ethynylestradiol (EE2) is a synthetic estrogen identified in sewage effluents. To understand better the absorption kinetics of EE2 and the induction of vitellogenin (VTG) and estrogen receptor , (ER,) mRNA, we subjected male rainbow trout (Onchorynchus mykiss) to continuous water exposures of 125 ng/L of EE2 for up to 61 d. Trout were either repetitively sampled for blood plasma or serially killed at selected time intervals. Vitellogenin, ER, mRNA, and EE2 were measured using enzymelinked immunosorbent assay and using quantitative polymerase chain reaction and gas chromatography,mass spectrometry, respectively. In separate experiments, trout were exposed to EE2 for 7 d, and hepatic gene expression was assessed using a low- and high-density cDNA microarray. The EE2 was rapidly absorbed by the trout, with an apparent equilibrium at 16 h in plasma and liver. The ER, mRNA levels also increased rapidly, reaching near-peak levels by 48 h. In contrast, plasma levels of VTG continuously increased for 19 d. After 61 d, tissues with the highest levels of VTG were the liver, kidney, and testes. Microarray-based gene expression studies provided unexpected results. In some cases, known estrogen-responsive genes (e.g., ER,) were unresponsive, whereas many of the genes that have no apparent link to estrogen function or EE2 toxicity were significantly altered in expression. Of the two microarray approaches tested in the present study, the high-density array appeared to be superior because of the improved quality of the hybridization signal and the robustness of the response in terms of the number of genes identified as being EE2 responsive. [source] Stimulation of reproductive growth in rainbow trout (Oncorhynchus mykiss) following exposure to treated sewage effluentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2006Birgit Hoger Abstract Rainbow trout (Oncorhynchus mykiss) were exposed to 1.5 and 15% v/v secondary treated sewage effluent for 32 weeks in flow-through mesocosms. The exposure encompassed the full period of reproductive development for rainbow trout. Trout did not show any evidence of a dose-dependent change in growth. Fish exposed to 15% effluent were the only group to show mortality (5%) over the duration of the experiment. Trout at the highest effluent concentration had significantly higher liver size than reference water fish. Both male and female trout in the 15% exposure group also exhibited significantly higher gonad weight than the reference group. In female trout, this gonad size increase could be explained by higher egg numbers. Female and male trout both displayed a significant increase in plasma 17,-estradiol levels after exposure to 15% effluent, while neither sex had dose-dependent differences in plasma testosterone. Male trout displayed elevated vitellogenin levels and reduced plasma 11-ketotestosterone concentration after exposure to 15% effluent. Chemical examination of steroidal compounds, including both estrogens and androgens, in the wastewater revealed that only estrone was detectable at a mean concentration of 4.5 ng/L. It is assumed that the effects observed in trout exposed to 15% effluent were consistent with stimulation of reproductive development due to very low levels of estrogens. Overall, long-term exposure to treated sewage effluent containing low levels of estrogen did not have significant negative implications for reproductive development in rainbow trout. [source] Use of the oligochaete, Lumbriculus variegatus, as a prey organism for toxicant exposure of fish through the dietENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2006David R. Mount Abstract The oligochaete, Lumbriculus variegatus, has several characteristics that make it desirable as a prey organism for conducting dietary exposure studies with fish. We conducted 21- and 30-d experiments with young fathead minnows (Pimephales promelas) and rainbow trout (Oncorhynchus mykiss), respectively, to determine whether a diet consisting solely of L. variegatus would support normal growth and to compare performance with standard diets (Artemia nauplii, frozen brine shrimp, or trout chow). All diets were readily accepted, and fish survived and grew well. Food conversion in both fathead minnows and rainbow trout was as high as or higher for the oligochaete diet compared with others, although this comparison is influenced by differences in ration, ingestion rate, or both. The oligochaete diet had gross nutritional analysis similar to the other diets, and meets fish nutrition guidelines for protein and essential amino acids. Methodologies and practical considerations for successfully using oligochaetes as an experimental diet are discussed. Considering their ready acceptance by fish, their apparent nutritional sufficiency, the ease of culturing large numbers, and the ease with which they can be loaded with exogenous chemicals, we believe that L. variegatus represents an excellent choice of exposure vector for exposing fish to toxicants via the diet. [source] Dietary accumulation of hexabromocyclododecane diastereoisomers in juvenile rainbow trout (Oncorhynchus mykiss) I: Bioaccumulation parameters and evidence of bioisomerizationENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2006Kerri Law Abstract Juvenile rainbow trout (Oncorhynchus mykiss) were exposed to three diastereoisomers (,, ,, ,) of hexabromocyclododecane (C12H18Br6) via their diet for 56 d followed by 112 d of untreated food to examine bioaccumulation parameters and test the hypothesis of in vivo bioisomerization. Four groups of 70 fish were used in the study. Three groups were exposed to food fortified with known concentrations of an individual diastereoisomer, while a fourth group were fed unfortified food. Bioaccumulation of the ,-diastereoisomer was linear during the uptake phase, while the ,- and ,-diastereoisomers were found to increase exponentially with respective doubling times of 8.2 and 17.1 d. Both the ,- and the ,-diastereoisomers followed a first-order depuration kinetics with calculated half-lives of 157 ± 71 and 144 ± 60 d (±1 × standard error), respectively. The biomagnification factor (BMF) for the ,-diastereoisomer (BMF = 9.2) was two times greater than the ,-diastereoisomer (BMF = 4.3); the large BMF for the ,-diastereoisomer is consistent with this diastereoisomer dominating higher-trophic-level organisms. Although the BMF of the ,-diastereoisomer suggests that it will biomagnify, it is rarely detected in environmental samples because it is present in small quantities in commercial mixtures. Results from these studies also provide evidence of bioisomerization of the ,- and ,-diastereoisomers. Most importantly, the ,-diastereoisomer that was recalcitrant to bioisomerization by juvenile rainbow trout in this study and known to be the dominant diastereosiomer in fish was bioformed from both the ,- and the ,-diastereoisomers. To our knowledge, this is the first report of bioisomerization of a halogenated organic pollutant in biota. [source] Development of a solvent-free, solid-phase in vitro bioassay using vertebrate cellsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2006Stephanie K. Bopp Abstract Miniaturized bioassays offer many advantages in exploring the toxic potential of chemicals, including small sample volumes and compatibility with high-throughput screening. One problem common to miniaturized systems, however, is the loss of test chemicals because of sorption. The idea of the current study was to use the sorption phenomenon in a positive way. It was found that contaminants sorbed to the growth surface in wells of tissue-culture plates or to the surface of selected sorbent bead materials are available to vertebrate cells growing in direct contact with the contaminant-coated surface. The use of beads provided more flexibility with regard to surface area, materials, and assay format. Biosilon, a bead cell-culture carrier made of polystyrene, was found to be most suitable. It supported cell adherence and allowed the detection of reproducible dose-response curves of an increase in cytochrome CYP1A enzyme activity by sorbed polycyclic aromatic hydrocarbons in the rainbow trout (Oncorhynchus mykiss) liver cell line, RTL-W1. The resulting bead assay provides a miniaturized, solvent-free exposure system. Potential future applications include the coupling to environmental sampling, in which the bead material is used as solid receiving phase before serving as a surface for vertebrate cells to attach and respond. [source] Gene expression in caged fish as a first-tier indicator of contaminant exposure in streamsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2005Aaron P. Roberts Abstract The development of sensitive, biologically based indicators of contaminant exposure (i.e., biomarkers) is an ongoing topic of research. These indicators have been proposed as a first-tier method of identifying contaminant exposure. The primary objective of this research was to implement a biomarker-based method of exposure assessment using caged fish and real-time reverse-transcriptase polymerase chain reaction (rtRT-PCR) measurements of gene expression. Primers were developed for the CYPIA, metallothionein, and vitellogenin genes in rainbow trout (Oncorhynchyus mykiss), cutbow trout (Oncorhynchyus clarkii × mykiss), and Atlantic salmon (Salmo salar). Each of these genes has been shown to respond specifically to planar aromatic compounds, heavy metals, and environmental estrogens, respectively. Juvenile fish were placed in cages and exposed in situ at reference and contaminated sites on the Cache la Poudre River (CO, USA), the Arkansas River (CO, USA), the St. John River (NB, Canada), and two urban creeks near Dayton (OH, USA). Quantitative gene expression was determined using rtRT-PCR. Biomarker expression profiles were obtained that demonstrated differences in CYP1A, metallothionein, and vitellogenin mRNA production unique to each site, indicating that specific types of compounds were bioavailable and present in sufficient concentrations to elicit transcriptional responses in the organism. These findings support the use of a biomarker-based approach to exposure identification and assessment. [source] Developmental effects of bioaccumulated selenium in eggs and larvae of two salmonid speciesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2005Jodi Holm Abstract Elevated concentrations of Se have been detected in cold, flowing water habitats near uranium and coal mines in Canada. Fish from these systems have concentrations of Se in their tissues that exceed toxic effect thresholds that have been established for warm-water fishes. However, the applicability of toxic effect thresholds and guidelines to cold water, lotic habitats is a matter of contention in the literature since most cases of Se toxicosis have been documented in standing, warm-water systems. To examine the possibility of impaired reproduction in wild rainbow trout (Oncorhynchus mykiss) and brook trout (Salvelinus fontinalis) near coal mining activity in the northeastern slopes region of Alberta, Canada, spawn from both species were collected from exposure and reference sites. Gametes were fertilized in the laboratory, reared to the swim-up stage, and examined for deformities. A significant relationship was observed for rainbow trout between the amount of Se in eggs and the incidence of developmental abnormalities, specifically craniofacial defects, skeletal deformities, and edema. These associations approximate exponential functions with probabilities that 15% of the population would be affected occurring between 8.8 and 10.5 ,g Se per gram of wet egg weight, based on probit analysis. These relationships are similar to those described for centrarchids inhabiting a seleniferous warm-water lake. No such relationships were established for brook trout. [source] Reduced growth of rainbow trout (Oncorhynchus mykiss) fed a live invertebrate diet pre-exposed to metal-contaminated sedimentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2004James A. Hansen Abstract Juvenile rainbow trout (Oncorhynchus mykiss) were fed live diets of Lumbriculus variegatus cultured in metal-contaminated sediments from the Clark Fork River Basin (MT, USA), an uncontaminated reference sediment, or an uncontaminated culture medium. Fish were tested in individual chambers; individual growth as well as the nutritional quality and caloric value of each trout's consumed diet were determined. Growth was measured following 14, 28, 42, 56, and 67 d of exposure. A subset of fish was sampled at 35 d for whole-body metals. Metals (whole body, digestive tract, and liver) and histology were measured at the end of the test. We observed significant growth inhibition in trout fed the contaminated diets; growth inhibition was associated with reductions in conversion of food energy to biomass rather than with reduced food intake. Growth inhibition was negatively correlated with As in trout tissue residues. Histological changes in contaminated treatments included hepatic necrosis and degenerative alterations in gallbladder. The present study provides evidence that metal-contaminated sediments can pose a hazard to trout health through a dietary exposure pathway. [source] Toxicity and chemistry of aspen wood leachate to aquatic life: Field studyENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2003Barry R. Taylor Abstract A dark, toxic leachate has been observed around woodpiles of trembling aspen (Populus tremuloides Michx.) cut in winter for pulp or structural lumber. We measured production of leachate from 18 m3 of harvestable aspen logs stacked in an open field near Dawson Creek, British Columbia, Canada. The logpile began producing leachate during the first winter thaw and continued to do so for the duration of the two-year study (mean, 250 L/collection). Aspen leachate was characterized by dark color, acidic pH (5.0-6.5), elevated conductivity (200-500 ,S/cm), high to very high biochemical oxygen demand (500-5,000 mg/L) and total organic carbon concentrations (500-2,000 mg/L), variable levels of phenolic compounds (2-27 mg/L), and low dissolved oxygen tensions (<2 mg/L). In tests with rainbow trout (Oncorhynchus mykiss), Daphnia magna, and luminescent bacteria, the leachate varied from weakly toxic (median lethal concentration, >10%) to very toxic (median lethal concentration, <1%). The volume of leachate generated by the logpile was correlated with total precipitation (rain or snow) since the last collection. Loads of chemical constituents or toxicity (lethal concentration × volume) in the leachate did not decline over the duration of the study. Less than 10% of the total mass of leachable material in the aspen logs was removed during two years of exposure. [source] Dietary accumulation of perfluorinated acids in juvenile rainbow trout (Oncorhynchus mykiss)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2003Jonathan W. Martin Abstract Perfluorinated acids (PFAs) recently have emerged as persistent global contaminants after their detection in wildlife and humans from various geographic locations. The highest concentrations of perfluorooctane sulfonate are characteristically observed in high trophic level organisms, indicating that PFAs may have a significant bioaccumulation potential. To examine this phenomenon quantitatively, we exposed juvenile rainbow trout (Oncorhynchus mykiss) simultaneously to a homologous series of perfluoroalkyl carboxylates and sulfonates for 34 d in the diet, followed by a 41-d depuration period. Carcass and liver concentrations were determined by using liquid chromatography-tandem mass spectrometry, and kinetic rates were calculated to determine compound-specific bioaccumulation parameters. Depuration rate constants ranged from 0.02 to 0.23/d, and decreased as the length of the fluorinated chain increased. Assimilation efficiency was greater than 50% for all test compounds, indicating efficient absorption from food. Bioaccumulation factors (BAFs) ranged from 0.038 to 1.0 and increased with length of the perfluorinated chain; however, BAFs were not statistically greater than 1 for any PFA. Sulfonates bioaccumulated to a greater extent than carboxylates of equivalent perfluoroalkyl chain length, indicating that hydrophobicity is not the sole determinant of PFA accumulation potential and that the acid function must be considered. Dietary exposure will not result in biomagnification of PFAs in juvenile trout, but extrapolation of these bioaccumulation parameters to larger fish and homeothermic organisms should not be performed. [source] Altering cytochrome P4501A activity affects polycyclic aromatic hydrocarbon metabolism and toxicity in rainbow trout (Oncorhynchus mykiss)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2002Stephanie A. Hawkins Abstract The polycyclic aromatic hydrocarbons (PAHs) phenanthrene and retene (7-isopropyl-1-methyl phenanthrene) are lethal to rainbow trout (Oncorhynchus mykiss) larvae during chronic exposures. Phenanthrene is a low-toxicity, non-cytochrome P4501A (CYP1A),inducing compound that accumulates in fish tissues during exposure to lethal concentrations in water. Retene is a higher toxicity CYP1A-inducing compound that is not detectable in tissue at lethal exposure concentrations. The metabolism, excretion, and toxicity of retene and phenanthrene were examined in juvenile and larval rainbow trout during coexposure to the model CYP1A inducer ,-naphthoflavone (,NF), or to the inducer-inhibitor piperonyl butoxide to determine if modulating CYP1A activity affected PAH metabolism and toxicity. Phenanthrene metabolism, excretion rate, and toxicity increased with coexposure to ,NF. Piperonyl butoxide inhibited phenanthrene metabolism and reduced the excretion of all phenanthrene metabolites. As a consequence, embryo mortality rates increased but rates of sublethal effects did not. Coexposure of trout to retene and ,NF caused no change in retene metabolism and excretion, but retene toxicity increased, perhaps due to additivity. Piperonyl butoxide inhibited retene metabolism, decreased the excretion of some retene metabolites while increasing the excretion of others, and increased the toxicity of retene. These results support the role of CYP1A activity in PAH metabolism and excretion, and the role of the CYP1A-generated metabolites of PAHs in chronic toxicity to larval fish. [source] Development of a fish reporter gene system for the assessment of estrogenic compounds and sewage treatment plant effluentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2002Gabriele E. Ackermann Abstract This study reports on the development and application of a fish-specific estrogen-responsive reporter gene assay. The assay is based on the rainbow trout (Oncorhynchus mykiss) gonad cell line RTG-2 in which an acute estrogenic response is created by cotransfecting cultures with an expression vector containing rainbow trout estrogen receptor a complementary DNA (rtER, cDNA) in the presence of an estrogen-dependent reporter plasmid and an estrogen receptor (ER) agonist. In a further approach, RTG-2 cells were stably transfected with the rtER, cDNA expression vector, and clones responsive to 17,-estradiol (E2) were selected. The estrogenic activity of E2, 17,-ethinylestradiol, 4-nonylphenol, nonylphenoxy acetic acid, 4- tert -octylphenol, bisphenol A, o,p,-DDT, p,p,-DDT, o,p,-2,2-bis(chlorophenyl)-1,1-dichloroethylene (o,p,-DDE), p,p,-DDE, o,p,-2,2-bis(chlorophenyl)-1,1-di-chloroethane (o,p,-DDD), p,p,-DDD, and p,p,-2,2-bis(chlorophenyl)acetic acid (p,p,-DDA) was assessed at increasing concentrations. All compounds except o,p,-DDT, p,p,-DDE, and p,p,-DDA showed logistic dose-response curves, which allowed the calculation of lowest-observed-effect concentrations and the concentrations at which half-maximal reporter gene activities were reached. To check whether estrogen-responsive RTG-2 cells may be used to detect the estrogenic activity of environmental samples, an extract from a sewage treatment plant (STP) effluent was assessed and found to have estrogenic activity corresponding to the transcriptional activity elicited by 0.05 nM of E2. Dose-response curves of nonylphenol, octylphenol, bisphenol A, and o,p,-DDD revealed that the RTG-2 reporter gene assay is more sensitive for these compounds when compared to transfection systems recombinant for mammalian ERs. These differences may have an effect on the calculation of E2 equivalents when estrogenic mixtures of known constitution, or environmental samples, such as STP effluents, are assessed. [source] The further development of ionoregulatory measures as biomarkers of sensitivity and effect in fish speciesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2002S. J. Croke Abstract Extensive season-by-season sampling was used to establish the normal range of whole-body Na+ and Cl, and Na+ uptake in healthy populations of two fish species, rainbow trout, Oncorhynchus mykiss, and fathead minnow, Pimephales promelas, of known differences in sensitivity to ionoregulatory toxicants (low pH, trace metals). These data together with responses of both species to six different ionoregulatory challenge tests of increasing severity (mild handling, exposure to low Ca2+ water, epinephrine injection, net-confinement stress, exposure to copper, and osmotic shock) were evaluated for their potential as biomarkers of sensitivity and of effect of ionoregulatory toxicants. There were no obvious biomarkers of sensitivity in the ion measures themselves, but four of the six challenges (exposure to low Ca2+ water, epinephrine injection, exposure to copper, and osmotic shock) produced a significantly greater effect in the more sensitive of the two species, fathead minnow. Based on the responses of both species, this article makes a number of recommendations for the application of ion measures alone and in combination with challenge tests to the assessment of chronic effects in populations experiencing sublethal ionoregulatory stress. [source] Aquatic toxicity of triclosanENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2002David R. Orvos Abstract The aquatic toxicity of triclosan (TCS), a chlorinated biphenyl ether used as an antimicrobial in consumer products, was studied with activated-sludge microorganisms, algae, invertebrates, and fish. Triclosan, a compound used for inhibiting microbial growth, was not toxic to wastewater microorganisms at concentrations less than aqueous solubility. The 48-h Daphnia magna median effective concentration (EC50) was 390 ,g/L and the 96-h median lethal concentration values for Pimephales promelas and Lepomis macrochirus were 260 and 370 ,g/L, respectively. A no-observed-effect concentration (NOEC) and lowest-observed-effect concentration of 34.1 ,g/L and 71.3 ,g/L, respectively, were determined with an early life-stage toxicity test with Onco-rhynchus mykiss. During a 96-h Scenedesmus study, the 96-h biomass EC50 was 1.4 ,g/L and the 96-h NOEC was 0.69 ,g/L. Other algae and Lemna also were investigated. Bioconcentration was assessed with Danio rerio. The average TCS accumulation factor over the five-week test period was 4,157 at 3 ,g/L and 2,532 at 30 ,g/L. Algae were determined to be the most susceptible organisms. Toxicity of a TCS-containing wastewater secondary effluent to P. promelas and Ceriodaphnia was evaluated and no observed differences in toxicity between control and TCS-treated laboratory units were detected. The neutral form of TCS was determined to be associated with toxic effects. Ionization and sorption will mitigate those effects in the aquatic compartment. [source] Effects of handling on heat shock protein expression in rainbow trout (Oncorhynchus mykiss)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2002Barbara Shayne Washburn Abstract As part of an effort to validate the use of heat shock proteins (HSPs) as biomarkers of exposure to and effects of contaminants, we evaluated the effect of two handling regimens on the induction of HSP 60 and 70 in rainbow trout (Oncorhynchus mykiss). Fish were acclimated to laboratory conditions for several weeks before the beginning of the experiment. Fish were then captured by net, placed in a cooler for 1 h while being transported in a truck, returned to their original tanks, then sacrificed 6 to 8 h later. Tricaine methane sulfonate (MS-222) was used during different phases of handling to reduce handling stress. Heat-stressed fish were included in the experiment as a positive control. Muscle, liver, gills, and heart were analyzed for HSP 60 and 70 by immunoblotting. We found no effect of any handling regimen on the induction of HSPs. These findings suggest that the capture and transport of fish for environmental monitoring purposes should not interfere with the use of stress proteins as biomarkers. [source] Relative sensitivity of bull trout (Salvelinus confluentus) and rainbow trout (Oncorhynchus mykiss) to acute copper toxicityENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2002James A. Hansen Abstract Bull trout (Salvelinus confluentus) were recently listed as threatened in the United States under the federal Endangered Species Act. Past and present habitat for this species includes waterways contaminated with heavy metals released from mining activities. Because the sensitivity of this species to copper was previously unknown, we conducted acute copper toxicity tests with bull and rainbow trout (Oncorhynchus mykiss) in side-by-side comparison tests. Bioassays were conducted using water at two temperatures (8°C and 16°C) and two hardness levels (100 and 220 mg/L as CaCO3). At a water hardness of 100 mg/L, both species were less sensitive to copper when tested at 16°C compared to 8°C. The two species had similar sensitivity to copper in 100-mg/L hardness water, but bull trout were 2.5 to 4 times less sensitive than rainbow trout in 220-mg/L hardness water. However, when our results were viewed in the context of the broader literature on rainbow trout sensitivity to copper, the sensitivities of the two species appeared similar. This suggests that adoption of toxicity thresholds that are protective of rainbow trout would be protective of bull trout; however, an additional safety factor may be warranted because of the additional level of protection necessary for this federally threatened species. [source] Adding magnesium to the silver-gill binding model for rainbow trout (Oncorhynchus mykiss)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2001Melissa L. Schwartz Abstract Rainbow trout (Oncorhynchus mykiss; 2,17 g) were exposed to approximately 0.1 ,M silver as AgNO3 for 3 to 4 h in synthetic, ion-poor water (20 ,M Ca, 100 ,M Na, 150 ,M Cl, pH 7) to which was added Mg, Ca, or thiosulfate (S2O3). Gills were extracted and assayed for Ag using graphite furnace atomic absorption spectrophotometry. Up to 210 mM Mg (four fold the concentration of Mg in seawater) did not reduce accumulation of Ag by trout gills. The conditional equilibrium stability constant (K) for Mg at silver-binding sites on the gills was calculated to be log KMg-gillAg = 3.0, or approximately half-as-strong binding as for Ca at these sites. The inclusion of the Mg-gill stability constant into the original Ag-gill binding model increases the flexibility of the model, although the competitive effects of Mg are only important in sodium-poor systems. [source] Chronic effects of silver exposure on ion levels, survival, and silver distribution within developing rainbow trout (Oncorhynchus mykiss) embryosENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2001Christine M. Guadagnolo Abstract Rainbow trout embryos were chronically exposed to silver (as AgNO3) in moderately hard water (120 mg CaCO3/L, 0.70 mM Cl,, 1.3 mg/L dissolved organic matter, 12.3 ± 0.1 °C) at nominal concentrations of 0.1, 1, and 10 ,g/L (measured = 0.117 ± 0.008, 1.22 ± 0.16, and 13.51 ± 1.58 ,g/L, respectively) to investigate the effects on mortality, ionoregulation, and silver uptake and distribution of the embryo. Mortalities in the low concentrations (0.1 and 1.2 ,g/L) were not significantly different from controls throughout embryonic development (days 1,32 postfertilization). Mortalities of embryos in the 13.5-,g/L treatment reached 56% by day 32 postfertilization (33% when accounting for control mortality), by which time more than 50% of surviving embryos had hatched. Accumulation of silver in whole embryos of 1.2- and 13.5-,g/L treatments reached the highest concentrations of 0.13 and 0.24 ,g/g total silver, respectively, by day 32, but whole embryo silver burden was not correlated with mortality. Silver concentrations in different compartments of the whole embryo (chorion, dissected embryo, and yolk) were greatest just before hatch and were higher in the chorion for all experimental treatments. Up to 85% of total whole embryo silver content was bound to the chorion, which acts as a protective barrier during silver exposure. Whole embryo Na+ concentration in the 13.5-,g/L treatment was significantly reduced relative to controls from days 23 to 32 postfertilization, and levels in the embryo were reduced by 40% at day 32 postfertilization, indicating that silver toxicity in the whole embryo is associated with an ion regulatory disturbance that is similar to the acute effect of AgNO3 in juvenile and adult trout. [source] Polycyclic aromatic hydrocarbons as inducers of cytochrome P4501A enzyme activity in the rainbow trout liver cell line, RTL-W1, and in primary cultures of rainbow trout hepatocytesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2001Anja Behrens Abstract In order to investigate cell-specific differences in the response of in vitro models to environmental toxicants, we compared the capacity of nine polycyclic aromatic hydrocarbons (PAHs) to induce cytochrome P4501A (CYP1A) in primary rainbow trout (Oncorhynchus mykiss) hepatocytes and a rainbow trout liver cell line, RTL-W1. Induction of CYP1A was estimated from the catalytic activity of 7-ethoxyresorufin- O -deethylase (EROD) and compared by median effective concentration (EC50) values, induction spans, and benzo[a]pyrene induction equivalency factors for inducing PAHs. The influence of culture conditions was investigated with respect to the presence or absence of serum and varying exposure times. Both in vitro systems lead to an identical classification of the PAHs in noninducing (anthracene, fluoranthene, phenanthrene, and pyrene) and inducing compounds with a similar ranking of inducing PAHs. Mean EC50 values in RTL-W1 cells were, respectively, 343 and 266 nM for benzo[a]anthracene, 57 and 92 nM for BaP, 134 and 283 nM for benzo[b]fluoranthene, 455 and 270 nM for chrysene, and 98 and 116 nM for 3-methylcholanthrene. Compared to primary hepatocytes, the RTL-W1 cell line was more sensitive in its EROD response to the presence or absence of serum and to the increase in exposure time, which led to higher EC50 values. [source] | ||||||||||||||||