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Sample records for hyalella azteca 10-day

  1. 10-Day survival of Hyalella azteca as a function of water quality parameters.

    Science.gov (United States)

    Javidmehr, Alireza; Kass, Philip H; Deanovic, Linda A; Connon, Richard E; Werner, Inge

    2015-05-01

    Estuarine systems are among the most impacted ecosystems due to anthropogenic contaminants; however, they present unique challenges to toxicity testing with regard to varying water quality parameters. The euryhaline amphipod species, Hyalella azteca, is widely used in toxicity testing and well suited for testing estuarine water samples. Nevertheless, the influence of relevant water quality parameters on test endpoints must be quantified in order to efficiently use this species for routine monitoring. Here, we studied the influence of five water quality parameters: electrical conductivity, pH, un-ionized ammonia, dissolved oxygen and temperature, on H. azteca survival in a water column toxicity test. A model was developed to quantify and predict the independent and interacting effects of water quality variables on 10-day survival. The model allows simultaneous assessment of multiple potential predictors recorded during the tests. Data used for modeling came from 1089 tests performed on ambient water samples over a period of three years (2006-2008). The final model reflects significant effects of predictors and their two-way interactions. The effect of each level of all predictors on survival probability of H. azteca was examined by comparing levels of each predictor at a time, while holding all others at their lowest (reference) level. This study showed that predictors of survival in water column tests should not be evaluated in isolation in the interpretation of H. azteca water column tests. Our model provides a useful tool to predict expected control survival based on relevant water quality parameters, and thus enables the use of H. azteca tests for toxicity monitoring in estuaries with a wide range of water quality conditions.

  2. Relative toxicity of bifenthrin to Hyalella azteca in 10 day versus 28 day exposures.

    Science.gov (United States)

    Anderson, Brian S; Phillips, Bryn M; Voorhees, Jennifer P; Petersen, Megan A; Jennings, Lydia L; Fojut, Tessa L; Vasquez, Martice E; Siegler, Catherine; Tjeerdema, Ronald S

    2015-04-01

    Many watersheds in the Central Valley region of California are listed as impaired due to pyrethroid-associated sediment toxicity. The Central Valley Regional Water Quality Control Board is developing numeric sediment quality criteria for pyrethroids, beginning with bifenthrin. Criteria are being developed using existing data, along with data from 10 d and 28 d toxicity tests with Hyalella azteca conducted as part of the current study. A single range-finder and 2 definitive tests were conducted for each test duration. Median lethal concentrations (LC50s), as well as LC20s and inhibition concentrations (IC20s) were calculated based on measured whole sediment bifenthrin concentrations and interstitial water concentrations. Sediment LC50s were also corrected for organic C content. Average LC50s were not significantly different in 10 d versus 28 d tests with H. azteca: 9.1 and 9.6 ng/g bifenthrin for 10 d and 28 d tests, respectively. Average LC20 values were also similar with concentrations at 7.1 and 7.0 for 10 d and 28 d tests, respectively. Bifenthrin inhibition concentrations (IC20s) based on amphipod growth were variable, particularly in the 28 d tests, where a clear dose-response relationship was observed in only 1 of the definitive experiments. Average amphipod growth IC20s were 3.9 and 9.0 ng/g for 10 d and 28 d tests, respectively. Amphipod growth calculated as biomass resulted in IC20s of 4.1 and 6.3 ng/g for the 10 d and 28 d tests, respectively. Lack of a clear growth effect in the longer term test may be related to the lack of food adjustment to account for amphipod mortality in whole sediment exposures. The average C-corrected LC50s were 1.03 and 1.09 μg/g OC for the 10 d and 28 d tests, respectively. Interstitial water LC50s were determined as the measured dissolved concentration of bifenthrin relative to interstitial water dissolved organic carbon. The average LC50s for dissolved interstitial water bifenthrin were

  3. Responses of phytoplankton and Hyalella azteca to agrichemical mixtures in a constructed wetland mesocosm.

    Science.gov (United States)

    Lizotte, Richard E; Testa, Sam; Locke, Martin A; Steinriede, R Wade

    2013-10-01

    We assessed the capability of a constructed wetland to mitigate toxicity of a variety of possible mixtures, such as nutrients only (NO) (nitrogen [N], phosphorus [P]), pesticides only (PO) (atrazine, S-metolachlor, permethrin), and nutrients + pesticides on phytoplankton chlorophyll-a, on 48-h aqueous Hyalella azteca survival and 10-day sediment H. azteca survival and growth. Water and sediment were collected at 10-, 20-, and 40-m distances from inflow and analyzed for nutrients, pesticides, chlorophyll-a, and H. azteca laboratory bioassays. Phytoplankton chlorophyll-a increased 4- to 10 -fold at 7 days after NO treatment. However, responses of chlorophyll-a to PO and nutrients + pesticides were more complex with associated decreases at only 20 m for pesticides only and 10 and 40 m for nutrients + pesticides treatments. H. azteca aqueous survival decreased within the first 48 h of dosing at 10- and 20-m distances during PO and nutrients + pesticides treatments in association with permethrin concentrations. H. azteca sediment survival was unaffected, whereas 10-day growth decreased within 1 day of dosing at all sites during nutrients + pesticides treatment. Constructed wetlands were shown to be an effective agricultural best-management tool for trapping pollutants and mitigating ecological impacts of run-off in agricultural watersheds.

  4. Effects of copper in flooded Florida agricultural soils on Hyalella azteca.

    Science.gov (United States)

    Hoang, Tham C; Schuler, Lance J; Rand, Gary M

    2009-04-01

    This study examined the uptake and effects of copper (Cu) from flooded agricultural soils to epibenthic amphipods (Hyalella azteca) using 10-day sediment toxicity tests. Soils were collected from 10 citrus agricultural sites in South Florida. One sediment toxicity test was conducted with one flooding of the 10 soils, and based on the results of this test a second sediment toxicity test was conducted with 4 of the soils, after four 14-day flooding and four 14-day drying intervals over 4 months. Sediment toxicity tests were conducted under flow-through conditions using U.S. EPA methodology. Effects on survival, dry weight, and whole-body Cu concentrations of H. azteca were determined. Cu concentrations in overlying water and sediment of both sediment toxicity tests exceeded regulatory criteria for aquatic organisms. Although survival of H. azteca was not consistently affected from the first to the second sediment toxicity tests, dry weight was consistently reduced and related to Cu concentrations in soil, overlying water, and pore water. Furthermore, whole-body tissue Cu concentrations were significantly higher in H. azteca in all 10 soil-water treatments in the first sediment toxicity test and in all 4 soil-water treatments in the second sediment toxicity test compared to controls. Whole-body tissue concentrations and effects on dry weight were related to Cu exposures in soil, overlying water, and pore water. In these managed soil-water systems, small fish consuming H. azteca with high concentrations of Cu may be at risk.

  5. Toxicity of a cadmium-contaminated diet to Hyalella azteca.

    Science.gov (United States)

    Ball, Angela L; Borgmann, Uwe; Dixon, D George

    2006-09-01

    Four- and 10-week chronic toxicity tests were conducted using the freshwater amphipod Hyalella azteca and Cd-contaminated Chlorella sp. as a food source. Chlorella sp. was cultured in various Cd concentrations, filtered from solution, rinsed, dried, and ground into food flakes for the H. azteca. Unlike Cd toxicity from water sources, growth was found to be a more sensitive toxicological endpoint than survival, with calculated 50 and 25% effect concentrations (EC50s and EC25s, respectively) of 5.43 and 2.82 nmol/g, respectively, for Cd measured in food. Based on the regression of Cd in Chlorella sp. against Cd in filtered culture medium, the EC50 and EC25 corresponded to dissolved Cd concentrations of 11.30 and 5.09 nmol/L, respectively. Little or no bioaccumulation of Cd was found in the tissues of H. azteca that were fed contaminated food. These results demonstrate an apparent toxicological effect (either direct or indirect) of Cd-contaminated Chlorella sp. to H. azteca that is not associated with Cd accumulation. Toxicity of Cd-contaminated Chlorella sp. differs from waterborne Cd toxicity both in terms of the most sensitive endpoint (growth vs survival) and the relationship between toxicity and bioaccumulation. Unlike Cd toxicity through water exposure, Cd bioaccumulation by H. azteca cannot, therefore, be used to infer toxicity of Cd in a diet of Chlorella sp. Although the concentration of Cd in the algal culture medium that ultimately reduced growth of H. azteca in the present study was higher than Cd in water, which caused mortality to H. azteca in water-only tests during previous studies, further research regarding the contribution of dietary Cd to overall Cd toxicity is needed to verify that water-quality guidelines and risk assessments based on water-only exposures are fully protective.

  6. Reduced recruitment in Hyalella azteca (Saussure, 1858) exposed to copper.

    Science.gov (United States)

    Othman, M Shuhaimi; Pascoe, David

    2002-09-01

    Neonates of the amphipod Hyalella azteca were exposed for a 35-day period in the laboratory to a range of copper concentrations, nominally 18 microg/l, 40 microg/l, 70 microg/l and 260 microg/l. The reproductive status of the population was assessed by recording recruitment, the number of precopulatory pairs and number of gravid females. At the end of the experiment, the body lengths of individuals were measured using image analysis. There was a significant decrease in the final population size of H. azteca with increasing copper concentration and compared with the control. Copper significantly reduced recruitment of juveniles and length composition of the final population and there was also a trend toward reduced precopula number with increasing copper concentrations.

  7. Influence of bromide on the performance of the amphipod Hyalella azteca in reconstituted waters

    Science.gov (United States)

    Ivey, Chris D.; Ingersoll, Christopher G.

    2016-01-01

    Poor performance of the amphipod Hyalella azteca has been observed in exposures using reconstituted waters. Previous studies have reported success in H. azteca water-only exposures with the addition of relatively high concentrations of bromide. The present study evaluated the influence of lower environmentally representative concentrations of bromide on the response ofH. azteca in 42-d water-only exposures. Improved performance of H. azteca was observed in reconstituted waters with >0.02 mg Br/L.

  8. NMR-based metabolomics for the environmental assessment of Kaohsiung Harbor sediments exemplified by a marine amphipod (Hyalella azteca).

    Science.gov (United States)

    Chiu, K H; Dong, C D; Chen, C F; Tsai, M L; Ju, Y R; Chen, T M; Chen, C W

    2017-03-03

    Inflow of wastewater from upstream causes a large flux of pollutants to enter Kaohsiung Harbor in Taiwan daily. To reveal the ecological risk posed by Kaohsiung Harbor sediments, an ecological metabolomic approach was employed to investigate environmental factors pertinent to the physiological regulation of the marine amphipod Hyalella azteca. The amphipods were exposed to sediments collected from different stream inlets of the Love River (LR), Canon River (CR), Jen-Gen River (JR), and Salt River (SR). Harbor entrance 1 (E1) was selected as a reference site. After 10-day exposure, metabolomic analysis of the Hyalella azteca revealed differences between two groups: {E1, LR, CR} and {JR, SR}. The metabolic pathways identified in the two groups of amphipods were significantly different. The results demonstrated that NMR-based metabolomics can be effectively used to characterize metabolic response related to sediment from polluted areas.

  9. Modifying Foods and Feeding Regimes to Optimize the Performance of Hyalella azteca during Chronic Toxicity Tests

    Science.gov (United States)

    The amphipod Hyalella azteca is commonly used to assess the toxicity of sediments and waters. However, laboratories have reported varying success in maintaining healthy cultures and in obtaining consistent growth and reproduction (where applicable), especially during tests...

  10. Modifying Foods and Feeding Regimes to Optimize the Performance of Hyalella azteca during Chronic Toxicity Tests

    Science.gov (United States)

    The amphipod Hyalella azteca is commonly used to assess the toxicity of sediments and waters. However, laboratories have reported varying success in maintaining healthy cultures and in obtaining consistent growth and reproduction (where applicable), especially during tests...

  11. REPRODUCTIVE TOXICITY OF CHLORPYRIFOS, DIELDRIN, AND METHYL MERCURY MIXTURES TO THE AMPHIPOD, HYALELLA AZTECA

    Science.gov (United States)

    Toxicological interactions were assessed on the reproduction of the amphipod Hyalella azteca throughout a chronic exposure to methyl mercury (0.9, 4.7, 23.3 nM), chlorpyrifos (0.01, 0.05, 0.24), dieldrin (0.5, 2.3, 11.4 nM) and their binary mixtures. H. azteca were exposed to the...

  12. Responses of Hyalella azteca to acute and chronic microplastic exposures.

    Science.gov (United States)

    Au, Sarah Y; Bruce, Terri F; Bridges, William C; Klaine, Stephen J

    2015-11-01

    Limited information is available on the presence of microplastics in freshwater systems, and even less is known about the toxicological implications of the exposure of aquatic organisms to plastic particles. The present study was conducted to evaluate the effects of microplastic ingestion on the freshwater amphipod, Hyalella azteca. Hyalella azteca was exposed to fluorescent polyethylene microplastic particles and polypropylene microplastic fibers in individual 250-mL chambers to determine 10-d mortality. In acute bioassays, polypropylene microplastic fibers were significantly more toxic than polyethylene microplastic particles; 10-d lethal concentration 50% values for polyethylene microplastic particles and polypropylene microplastic fibers were 4.64 × 10(4) microplastics/mL and 71.43 microplastics/mL, respectively. A 42-d chronic bioassay using polyethylene microplastic particles was conducted to quantify effects on reproduction, growth, and egestion. Chronic exposure to polyethylene microplastic particles significantly decreased growth and reproduction at the low and intermediate exposure concentrations. During acute exposures to polyethylene microplastic particles, the egestion times did not significantly differ from the egestion of normal food materials in the control; egestion times for polypropylene microplastic fibers were significantly slower than the egestion of food materials in the control. Amphipods exposed to polypropylene microplastic fibers also had significantly less growth. The greater toxicity of microplastic fibers than microplastic particles corresponded with longer residence times for the fibers in the gut. The difference in residence time might have affected the ability to process food, resulting in an energetic effect reflected in sublethal endpoints.

  13. Toxicity of manganese to Ceriodaphnia dubia and Hyalella azteca

    Science.gov (United States)

    Lasier, P.J.; Winger, P.V.; Bogenrieder, K.J.

    2000-01-01

    Manganese is a toxic element frequently overlooked when assessing toxicity of effluents, sediments and pore waters. Manganese can be present at toxic levels in anoxic solutions due to its increased solubility under chemically-reducing conditions, and it can remain at those levels for days in aerated test waters due to slow precipitation kinetics. Ceriodaphnia dubia and Hyalella azteca are freshwater organisms often used for toxicity testing and recommended for assessments of effluents and pore waters. Lethal and reproductive-inhibition concentrations of Mn were determined for C. dubia in acute 48h tests and chronic 3-brood tests using animals Manganese concentrations were measured analytically at test initiation and after 96 h for calculations of toxicity endpoints and determinations of Mn precipitation during the tests. Minimal amounts of Mn (below 3%) precipitated within 96 h. LC50s determined for H. azteca progressively increased from 3.0 to 8.6 to 13.7 mg Mn/L in soft, moderately-hard and hard waters, respectively. The tolerance of C. dubia to Mn was not significantly different between moderately-hard and hard waters, but was significantly lower in soft water. There was no significant difference in Mn sensitivity between the ages of C. dubia tested. Acute LC50 values for C. dubia averaged 6.2, 14.5 and 15.2 mg Mn/L and chronic IC50 values averaged 3.9, 8.5 and 11.5 mg Mn/L for soft, moderately-hard and hard waters, respectively. Manganese toxicity should be considered when assessing solutions with concentrations near these levels.

  14. A comparison of the sublethal and lethal toxicity of four pesticides in Hyalella azteca and Chironomus dilutus.

    Science.gov (United States)

    Hasenbein, Simone; Connon, Richard E; Lawler, Sharon P; Geist, Juergen

    2015-08-01

    Laboratory toxicity testing is the primary tool used for surface water environmental risk assessment; however, there are critical information gaps regarding the sublethal effects of pesticides. In 10-day exposures, we assessed the lethal and sublethal (motility and growth) toxicities of four commonly used pesticides, bifenthrin, permethrin, cyfluthrin, and chlorpyrifos, on two freshwater invertebrates, Chironomus dilutus and Hyalella azteca. Pyrethroids were more toxic than the organophosphate chlorpyrifos in both species. Bifenthrin was most toxic to H. azteca survival and growth. Cyfluthrin was most toxic to C. dilutus. However, cyfluthrin had the greatest effect on motility on both H. azteca and C. dilutus. The evaluated concentrations of chlorpyrifos did not affect C. dilutus motility or growth, but significantly impacted H. azteca growth. Motility served as the most sensitive endpoint in assessing sublethal effects at low concentrations for both species, while growth was a good indicator of toxicity for all four pesticides for H. azteca. The integration of sublethal endpoints in ambient water monitoring and pesticide regulation efforts could improve identification of low-level pesticide concentrations that may eventually cause negative effects on food webs and community structure in aquatic environments.

  15. Acute toxicity of pyraclostrobin and trifloxystrobin to Hyalella azteca.

    Science.gov (United States)

    Morrison, Shane A; McMurry, Scott T; Smith, Loren M; Belden, Jason B

    2013-07-01

    Fungicide application rates on row crop agriculture have increased across the United States, and subsequently, contamination of adjacent wetlands can occur through spray drift or field runoff. To investigate fungicide toxicity, Hyalella azteca amphipods were exposed to 2 fungicide formulations, Headline and Stratego, and their active strobilurin ingredients, pyraclostrobin and trifloxystrobin. Water-only exposures resulted in similar median lethal concentration (LC50; 20-25 µg/L) values for formulations and strobilurin ingredients, suggesting that toxicity is due to strobilurin ingredients. These values were below concentrations that could occur following spray drift over embedded cropland wetlands. When fungicides were added to overlying water of sediment-water microcosms, toxicity was reduced by 500% for Headline and 160% for Stratego, compared with water-only exposures, based on the total amount of fungicide added to the systems. In addition, when fungicides were added to sediment prior to the addition of water, the reduction in toxicity was even greater, with no toxicity occurring at environmentally relevant levels. Differences in toxicity among exposure groups were explained by dissipation from water as toxicity values based on measured water concentrations were within 20% between all systems. The present study reinforces previous studies that Headline and Stratego are toxic to nontarget aquatic organisms. However, the presence of sediment is likely to ameliorate some toxicity of fungicide formulations, especially if spraying occurs prior to wetland inundation.

  16. Optimizing the performance of the amphipod, Hyalella azteca, in chronic toxicity tests: Results of feeding studies with various foods and feeding regimes

    Science.gov (United States)

    The freshwater amphipod, Hyalella azteca, is a common organism used for sediment toxicity testing. Standard methods for 10-d and 42-d sediment toxicity tests with H. azteca were last revised and published by USEPA/ASTM in 2000. While Hyalella azteca methods exist for sediment tox...

  17. Optimizing the performance of the amphipod, Hyalella azteca, in chronic toxicity tests: Results of feeding studies with various foods and feeding regimes

    Science.gov (United States)

    The freshwater amphipod, Hyalella azteca, is a common organism used for sediment toxicity testing. Standard methods for 10-d and 42-d sediment toxicity tests with H. azteca were last revised and published by USEPA/ASTM in 2000. While Hyalella azteca methods exist for sediment tox...

  18. DIFFERENTIAL DISPLAY ANALYSES OF THE AMPHIPOD HYALELLA AZTECA EXPOSED TO ETHYNYLESTRADIOL AT THREE DIFFERENT TROPHIC LEVELS

    Science.gov (United States)

    A study was conducted to determine if differential display could be used to detect differences in gene expression in the amphipod, Hyalella azteca. In a study of synthetic estrogen attenuation in different aquatic media, amphipods were exposed to 20 ng/L 17 a-ethynylestradiol in...

  19. Role of vegetation in a constructed wetland on nutrient-pesticide mixture toxicity of Hyalella azteca

    Science.gov (United States)

    The toxicity of a nutrient-pesticide mixture in non-vegetated and vegetated sections of a constructed wetland (60 X 30 X 0.3 m) was assessed using Hyalella azteca 48 h aqueous whole effluent toxicity bioassays. Both sections were amended with a mixture of sodium nitrate, triple super phosphate, dia...

  20. Responses of phytoplankton and Hyalella azteca to agrichemical mixtures in a constructed wetland mesocosms

    Science.gov (United States)

    We assessed the capability of a constructed wetland to mitigate toxicity of a variety of possible mixtures such as nutrients only (N, P), pesticides only (atrazine, S-metolachlor, permethrin), and nutrients+pesticides on phytoplankton chlorophyll a, 48 h aqueous Hyalella azteca survival, and 10 d se...

  1. Hyalella azteca Responses to Coldwater River Backwater Sediments in Mississippi, USA

    Science.gov (United States)

    Sediment from three Coldwater River, Mississippi backwaters was examined using 28 d Hyalella azteca bioassays and chemical analyses for 33 pesticides, 7 metals and 7 PCBs. Hydrologic connectivity between the main river channel and backwater varied widely among the three sites. Mortality occurred i...

  2. Effect on Hyalella azteca after pulse exposure to environmentally realistic concentrations of permethrin

    DEFF Research Database (Denmark)

    Pedersen, Signe; Palmqvist, Annemette; Forbes, Valery E.

    realistic pulse exposure and concentration of a pyrethroid pesticide, permethrin, on the freshwater amphipod Hyalella azteca. Permethrin is a pyrethroid insecticide used in mosquito control and to control a wide range of insect pests on various crops and is known to be highly toxic to aquatic invertebrates...

  3. Efficiency of experimental rice (Oryza sativa L.) fields in mitigating diazinon runoff toxicity to Hyalella azteca

    Science.gov (United States)

    This study assessed the viability of using planted, mature rice fields in mitigating diazinon (an organophosphate insecticide) runoff toxicity using aqueous 48 h Hyalella azteca whole effluent toxicity bioassays. Rice fields decreased diazinon concentrations 80.1-99.9% compared with 10.8% in the unv...

  4. DIFFERENTIAL DISPLAY ANALYSES OF THE AMPHIPOD HYALELLA AZTECA EXPOSED TO ETHYNYLESTRADIOL AT THREE DIFFERENT TROPHIC LEVELS

    Science.gov (United States)

    A study was conducted to determine if differential display could be used to detect differences in gene expression in the amphipod, Hyalella azteca. In a study of synthetic estrogen attenuation in different aquatic media, amphipods were exposed to 20 ng/L 17 a-ethynylestradiol in...

  5. Toxicity and transcriptomic analysis in Hyalella azteca suggests increased exposure and susceptibility of epibenthic organisms to Zinc Oxide Nanoparticles.

    Science.gov (United States)

    Nanoparticles (NPs) are expected to make their way into the aquatic environment where sedimentation of particles will likely occur, putting benthic organisms at particular risk. Therefore, organisms such as Hyalella azteca, an epibenthic crustacean which forages at the sediment ...

  6. Toxicity and transcriptomic analysis in Hyalella azteca suggests increased exposure and susceptibility of epibenthic organisms to Zinc Oxide Nanoparticles.

    Science.gov (United States)

    Nanoparticles (NPs) are expected to make their way into the aquatic environment where sedimentation of particles will likely occur, putting benthic organisms at particular risk. Therefore, organisms such as Hyalella azteca, an epibenthic crustacean which forages at the sediment ...

  7. TOXICOKINETIC INTERACTIONS AND SURVIVAL OF HYALELLA AZTECA EXPOSED TO BINARY MIXTURES OF CHLORPYRIFOS, DIELDRIN, AND METHYL MERCURY

    Science.gov (United States)

    Chemical mixture interactions of chlorpyrifos, dieldrin, and methyl mercury were evaluated in Hyalella azteca. Survival of adult and juvenile organisms was evaluated following exposure to individual chemicals and in binary combinations. Binary interactions of the model chemicals...

  8. Influence of bromide on the performance of the amphipod Hyalella azteca in reconstituted waters.

    Science.gov (United States)

    Ivey, Chris D; Ingersoll, Chris G

    2016-10-01

    Poor performance of the amphipod Hyalella azteca has been observed in exposures using reconstituted waters. Previous studies have reported success in H. azteca water-only exposures with the addition of relatively high concentrations of bromide. The present study evaluated the influence of lower environmentally representative concentrations of bromide on the response of H. azteca in 42-d water-only exposures. Improved performance of H. azteca was observed in reconstituted waters with >0.02 mg Br/L. Environ Toxicol Chem 2016;35:2425-2429. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America.

  9. Optimizing the performance of Hyalella azteca in chronic toxicity tests: Results of feeding studies with various foods and feeding regimes

    Science.gov (United States)

    The freshwater amphipod Hyalella azteca is a common organism used for sediment toxicity testing in the United States and elsewhere. Standard methods for 10-d and 42-d toxicity tests with H. azteca were last revised and published by USEPA/ASTM in 2000. Under the methods in the man...

  10. Optimizing the performance of Hyalella azteca in chronic toxicity tests: Results of feeding studies with various foods and feeding regimes

    Science.gov (United States)

    The freshwater amphipod Hyalella azteca is a common organism used for sediment toxicity testing in the United States and elsewhere. Standard methods for 10-d and 42-d toxicity tests with H. azteca were last revised and published by USEPA/ASTM in 2000. Under the methods in the man...

  11. Effects of an atrazine, metolachlor, and fipronil mixture on Hyalella azteca (Saussure) in a modified backwater wetland

    Science.gov (United States)

    We examined the toxicity mitigation efficiency of a hydrologically modified backwater wetland amended with a mixture of three pesticides, atrazine, metolachlor, and fipronil, using 96 h survival bioassays with Hyalella azteca. Significant H. azteca 96 h mortality occurred within the first two hours...

  12. Survival and precopulatory guarding behavior of Hyalella azteca (Amphipoda) exposed to nitrate in the presence of atrazine.

    Science.gov (United States)

    Pandey, Ram B; Adams, Ginny L; Warren, Laurie W

    2011-05-01

    Nitrate is one of the most commonly detected contaminants found in aquatic systems with other pesticides such as atrazine. The current study examined potential combined effects of nitrate and atrazine on adults of the freshwater amphipod Hyalella azteca, using survival and precopulatory guarding behavior as toxic endpoints. Although significant differences in acute toxicity with nitrate alone and in binary combination with atrazine (200 µg/L) in water-only tests were not consistently observed for each time point, potential biologically relevant trends in the data were observed. Posttest growth and behavioral observations (10-day period) conducted after 96-hour exposure suggested that atrazine and nitrate at these concentrations did not result in delayed effects on H. azteca. However, when test conditions were modified from standard toxicity tests by feeding amphipods, nitrate was found to be more toxic, with a reduction in median lethal concentration (LC50) values of approximately 80%. We also demonstrated that nitrate exhibits a dose-response effect on precopulatory guarding behavior of H. azteca, suggesting that reproductive effects may occur at environmentally relevant concentrations.

  13. Evaluation of toxicity: Whole-sediment versus overlying-water exposures with amphipod Hyalella azteca

    Science.gov (United States)

    Ingersoll, C.G.; Ivey, C.D.; Brunson, E.L.; Hardesty, D.K.; Kemble, N.E.

    2000-01-01

    A laboratory study was conducted to evaluate the toxicity of whole-sediment versus overlying-water exposures to the amphipod Hyalella azteca using field-collected sediments. Severe toxic effects (5-63% survival) were observed with amphipods exposed for 10 d in direct contact with sediment. In contrast, amphipods exposed only to overlying water in these sediment exposures did not exhibit any toxic effects.

  14. Modeling chronic dietary cadmium bioaccumulation and toxicity from periphyton to Hyalella azteca.

    Science.gov (United States)

    Golding, Lisa A; Borgmann, Uwe; Dixon, D George

    2011-07-01

    A chronic (28-d) Cd saturation bioaccumulation model was developed to quantify the Cd contribution from a natural periphyton diet to Cd in the freshwater amphipod Hyalella azteca. Bioaccumulation was then linked to chronic toxic effects. Juvenile H. azteca were exposed to treatments of Cd in water (3.13-100 nmol/L nominal) and food (389-26,300 nmol/g ash-free dry mass). Cadmium bioaccumulation, survival, and growth were recorded. Dietary Cd was estimated to contribute 21 to 31, 59 to 94, and 40 to 55% to bioaccumulated Cd in H. azteca exposed to treatments of Cd primarily in water, food, and food + water, respectively. Survival as a function of Cd lethal body concentration (679 nmol/g; 95% confidence limits, 617-747) was the most robust endpoint. Body concentration integrated all exposure routes. Based on the lethal body concentration, dietary Cd was predicted to contribute markedly (26-90%) to Cd in H. azteca. Cadmium concentration and food nutritional quality (biomass, chlorophyll a, total lipid, fatty acids, total protein) had no effect on H. azteca nutritional quality (total lipid, fatty acids, total protein) but did influence H. azteca dry weight. This research highlighted the importance of including a dietary component when modeling chronic effects of Cd and when refining endpoints for use in ecological risk assessment and water quality guidelines.

  15. The amphipod Hyalella azteca as a biomonitor in field deployment studies for metal mining

    Energy Technology Data Exchange (ETDEWEB)

    Couillard, Y. [Existing Substances Division, Science and Risk Assessment Directorate, Environment Canada, Place Vincent Massey, 351 St. Joseph Boulevard, 20th floor, Gatineau, Quebec, K1A 0H3 (Canada)], E-mail: yves.couillard@ec.gc.ca; Grapentine, L.C.; Borgmann, U. [Water Science and Technology Directorate, Environment Canada, 867 Lakeshore Road, Burlington, Ontario, L7R 4A6 (Canada); Doyle, P. [Existing Substances Division, Science and Risk Assessment Directorate, Environment Canada, Place Vincent Massey, 351 St. Joseph Boulevard, 20th floor, Gatineau, Quebec, K1A 0H3 (Canada); Masson, S. [Parc Aquarium du Quebec, 1675 avenue des Hotels, Quebec, Quebec, Canada G1W 4S3 (Canada)

    2008-12-15

    Specimens of the amphipod Hyalella azteca were deployed, in June-July 2003, along metal contamination gradients in two rivers affected by metal mining in the Abitibi - James Bay region, northwestern Quebec. The amphipods were placed along with natural food items in small, acrylic cages and left in six riverine sites for 17 days. Twelve metals (As, Cu, La, Mn, Ni, Sb, Se, Tl, U, V, Zn, and CrO{sub 4}{sup 2-} modelled by WHAM VI) in transplanted H. azteca varied along metal contamination gradients in a consistent manner, i.e., as a function of metal exposure. Bioaccumulation of As, Cr, La, Ni, Sb, Se, Tl, U and V, as defined by a field BCF, was significantly correlated with their chronic toxicity potential towards the amphipod. We conclude that H. azteca may be a useful field biomonitor for metal mining. In addition, our results suggest that such biomonitoring programs should include less studied elements such as Se in mining effluents. - Hyalella azteca accumulates dissolved metals in a dose-dependent manner.

  16. Interactive effects of phosphorus and copper on Hyalella azteca via periphyton in aquatic ecosystems.

    Science.gov (United States)

    Li, Miling; Costello, David M; Burton, G Allen

    2012-09-01

    This research examined the interaction between dissolved copper and phosphorus, with respect to their effects on the freshwater amphipod Hyalella azteca feeding on periphyton. Field-collected periphyton communities were exposed to different nutrient and metal conditions in indoor recirculating streams. H. azteca were then exposed to water and periphyton from these streams. There was rapid Cu accumulation by periphyton but the total Cu concentration of periphyton was not directly related to dissolved P. In terms of H. azteca growth, an interactive effect was found between Cu and P as growth was reduced more than expected in the low Cu-high P treatment. Our data suggest that eutrophic conditions result in greater Cu toxicity to benthic macroinvertebrates at lower metal concentrations, likely due to higher assimilation efficiency of dietary Cu from periphyton incubated under eutrophic conditions. These results imply that non-additive interactions between multiple stressors may cause ecosystem effects as detected in standard laboratory bioassays conducted under controlled conditions.

  17. Testing sediment biological effects with the freshwater amphipod Hyalella azteca: the gap between laboratory and nature.

    Science.gov (United States)

    Wang, Feiyue; Goulet, Richard R; Chapman, Peter M

    2004-12-01

    The freshwater amphipod, Hyalella azteca, is widely used in laboratory sediment toxicity and bioaccumulation tests. However, its responses in the laboratory are probably very different from those in the field. A review of the literature indicates that in its natural habitat this species complex is primarily epibenthic, derives little nutrition from the sediments, and responds primarily to contaminants in the overlying water column (including water and food), not sediment or porewater. In laboratory sediment toxicity tests H. azteca is deprived of natural food sources such as algal communities on or above the sediments, and is subjected to constant light without any cover except that afforded by burial into the sediments. Under these constraining laboratory conditions, H. azteca has been reported to respond to sediment or porewater contamination. In nature, contamination of overlying water from sediment is less likely than in the laboratory because of the large, generally non-static sink of natural surface water. H. azteca does not appear to be the most appropriate test species for direct assessments of the bioavailability and toxicity of sediment contaminants, though it is probably appropriate for testing the toxicity of surface waters. Toxic and non-toxic responses will be highly conservative, though the latter are probably the most persuasive given the exposure constraints. Thus H. azteca is probably a suitable surrogate species for determining sediments that are likely not toxic to field populations; however, it is not suitable for determining sediments that are likely toxic to field populations.

  18. Uptake and speciation of vanadium in the benthic invertebrate Hyalella azteca.

    Science.gov (United States)

    Jensen-Fontaine, Madeleine; Norwood, Warren P; Brown, Mitra; Dixon, D George; Le, X Chris

    2014-01-01

    Vanadium has the potential to leach into the environment from petroleum coke, an oil sands byproduct. To determine uptake of vanadium species in the biota, we exposed the benthic invertebrate Hyalella azteca with increasing concentrations of two different vanadium species, V(IV) and V(V), for seven days. The concentrations of vanadium in the H. azteca tissue increased with the concentration of vanadium in the exposure water. Speciation analysis revealed that V(IV) in the exposure water was oxidized to V(V) between renewal periods, and therefore the animals were mostly exposed to V(V). Speciation analysis of the H. azteca tissue showed the presence of V(V), V(IV), and an unidentified vanadium species. These results indicate the uptake and metabolism of vanadium by H. azteca. Because H. azteca are widely distributed in freshwater systems and are an important food supply for many fish, determining the uptake and metabolism of vanadium allows for a better understanding of the potential environmental effects on invertebrates.

  19. Interlaboratory study of precision: Hyalella azteca and Chironomus tentans freshwater sediment toxicity assays

    Science.gov (United States)

    Burton, G.A.; Norberg-King, T. J.; Ingersoll, C.G.; Benoit, D.A.; Ankley, G.T.; Winger, P.V.; Kubitz, J.; Lazorchak, J.M.; Smith, M.E.; Greer, E.; Dwyer, F.J.; Call, D.J.; Day, K.E.; Kennedy, P.; Stinson, M.

    1996-01-01

    Standard 10-d whole-sediment toxicity test methods have recently been developed by the U.S. Environmental Protection Agency (EPA) for the amphipod Hyalella azteca and the midge Chironomus tentans. An interlaboratory evaluation of method precision was performed using a group of seven to 10 laboratories, representing government, academia, and environmental consulting firms. The test methods followed the EPA protocols for 4-d water-only reference toxicant (KCl) testing (static exposure) and for 10-d whole-sediment testing. Test sediments included control sediment, two copper-containing sediments, and a sediment contaminated primarily with polycyclic aromatic hydrocarbons. Reference toxicant tests resulted in H. azteca and C. tentans median lethal concentration (LC50) values with coefficents of variation (CVs) of 15.8 and 19.6%, respectively. Whole sediments which were moderately contaminated provided the best estimates of precision using CVs. Hyalella azteca and C. tentans tests in moderately contaminated sediments exhibited LC50 CVs of 38.9 and 13.5%, respectively. The CV for C. tentans growth was 31.9%. Only 3% (1 of 28) of samples exceeded acceptable interlaboratory precision limits for the H. azteca survival tests. No samples exceeded the intralaboratory precision limit for H. azteca or C. tentans survival tests. However, intralaboratory variability limits for C. tentans growth were exceeded by 80 and 100% of the laboratories for a moderately toxic and control sample, respectively. Interlaboratory variability limits for C. tentans survival were not exceeded by any laboratory. The results showed these test methods to have relatively low variance and acceptable levels of precision in interlaboratory comparisons.

  20. Saturation models of arsenic, cobalt, chromium and manganese bioaccumulation by Hyalella azteca

    Energy Technology Data Exchange (ETDEWEB)

    Norwood, W.P. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada) and Aquatic Ecosystems Protection Research Branch, National Water Research Institute, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada)]. E-mail: warren.norwood@ec.gc.ca; Borgmann, U. [Aquatic Ecosystems Protection Research Branch, National Water Research Institute, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada); Dixon, D.G. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada)

    2006-10-15

    Bioaccumulation of As, Co, Cr and Mn by the benthic amphipod Hyalella azteca in Burlington City tap (Lake Ontario) water was measured in 4-week tests. Bioaccumulation increased with exposure concentration and demonstrated an excellent fit to a saturation model (r {sup 2}: 0.819, 0.838, 0.895 and 0.964 for As, Co, Cr and Mn, respectively). The proportion of total body Mn eliminated during a 24-h depuration period decreased as Mn body concentration increased, apparently due to a saturation of the elimination rate. The high maximum body concentration of 116,000 nmol g{sup -1} appears to result from the saturation of the Mn excretion which is slightly greater than the maximum Mn uptake rate. Elimination rates for As, Co and Cr were not dependent on body concentration. The four elements were not physiologically regulated in Hyalella. Their body concentrations should be good indicators of bioavailability and useful for environmental assessment. - Bioaccumulation of As, Co, Cr and Mn follow a saturation model in Hyalella azteca and can be useful for environmental assessment.

  1. Effects of an atrazine, metolachlor and fipronil mixture on Hyalella azteca (Saussure) in a modified backwater wetland.

    Science.gov (United States)

    Lizotte, Richard E; Knight, Scott S; Shields, F Douglas; Bryant, Charles T

    2009-12-01

    We examined the toxicity mitigation efficiency of a hydrologically modified backwater wetland amended with a pesticide mixture of atrazine, metolachlor, and fipronil, using 96 h survival bioassays with Hyalella azteca. Significant H. azteca 96 h mortality occurred within the first 2 h of amendment at the upstream amendment site but not at any time at the downstream site. H. azteca survival varied spatially and temporally in conjunction with measured pesticide mixture concentrations. Hyalella azteca 96 h survival pesticide mixture effects concentrations ranges were 10.214–11.997, 5.822–6.658, 0.650–0.817, and 0.030–0.048 μg L−1 for atrazine, metolachlor, fipronil, and fipronil-sulfone, respectively.

  2. Saturation models of arsenic, cobalt, chromium and manganese bioaccumulation by Hyalella azteca.

    Science.gov (United States)

    Norwood, W P; Borgmann, U; Dixon, D G

    2006-10-01

    Bioaccumulation of As, Co, Cr and Mn by the benthic amphipod Hyalella azteca in Burlington City tap (Lake Ontario) water was measured in 4-week tests. Bioaccumulation increased with exposure concentration and demonstrated an excellent fit to a saturation model (r(2): 0.819, 0.838, 0.895 and 0.964 for As, Co, Cr and Mn, respectively). The proportion of total body Mn eliminated during a 24-h depuration period decreased as Mn body concentration increased, apparently due to a saturation of the elimination rate. The high maximum body concentration of 116,000 nmol g(-1) appears to result from the saturation of the Mn excretion which is slightly greater than the maximum Mn uptake rate. Elimination rates for As, Co and Cr were not dependent on body concentration. The four elements were not physiologically regulated in Hyalella. Their body concentrations should be good indicators of bioavailability and useful for environmental assessment.

  3. Sediment Zn-release during post-drought re-flooding: Assessing environmental risk to Hyalella azteca and Daphnia magna.

    Science.gov (United States)

    Nedrich, Sara M; Burton, G Allen

    2017-11-01

    Hydrologic variability exacerbated by climate change affects biogeochemical cycling in sediments through changes in pH, redox, and microbial activity. These alterations affect the lability and speciation of metals, such that toxicity may be observed in otherwise non-toxic sediments. In this study, we investigate the effects of drought and reflooding on metal bioavailability in sediments with low to moderate concentrations of Zn (18-270 mg kg(-1)). Sediments were collected from coastal wetlands in Michigan, dried (36-days) and re-inundated in lab microcosms. We investigated the relationships between key parameters, for surface/porewater (dissolved and particulate metals, dissolved oxygen, redox (Eh), reduced iron, and temperature) and sediment (simultaneously extracted metals (SEM), acid volatile sulfide (AVS), Fe/Mn-oxyhydroxide, organic carbon, water content analyses, and diffusive gradient in thin films (DGTs) metal concentrations). Porewater Zn increased with inundation of dried sediments for all sediment types, exceeding United States Environmental Protection Agency (U.S. EPA) chronic criteria for freshwater organisms, and decreased as sediments became reduced. Effects on Hyalella azteca (7-day exposure) and Daphnia magna (10-day exposure) were quantified. Results show decreased growth of H. azteca for sites with elevated Zn and increased Zn-body concentration (BCZn) in the most contaminated sediment type. Further, BCZn was negatively correlated with H. azteca growth. D. magna survival, growth, and reproduction were not affected. DGT metal concentrations were more reflective of porewater than organism bioaccumulation. Outcomes of predictive toxicology methods are compared to toxicity test results and suggestions are provided for model improvements. This study demonstrates that post-drought re-flooding of sediments affects Zn biogeochemical cycling with potentially adverse effects on benthic organisms, even in sediments with only moderately elevated

  4. Efficiency of experimental rice (Oryza sativa L.) fields in mitigating diazinon runoff toxicity to Hyalella azteca.

    Science.gov (United States)

    Moore, Matthew T; Lizotte, Richard E; Kröger, Robert

    2009-06-01

    This study assessed the viability of using planted, mature rice fields in mitigating diazinon (an organophosphate insecticide) runoff toxicity using aqueous 48 h Hyalella azteca whole effluent toxicity bioassays. Rice fields decreased diazinon concentrations 80.1%-99.9% compared with 10.8% in the unvegetated field control. H. azteca survival responses coincided with observed diazinon concentrations. Estimated LC50 effects dilutions (%) ranged from 1.15 to 1.47 for inflow samples and 1.66 (unvegetated), 6.44 (rice field A), and >100 (rice field B) outflow samples. Decreases in inflow versus outflow aqueous toxicity were 77.1%-100% in rice fields compared with 18.7% in the unvegetated field.

  5. Diclofenac-enriched artificial sediment induces oxidative stress in Hyalella azteca.

    Science.gov (United States)

    Oviedo-Gómez, Dennis Gloria Carolina; Galar-Martínez, Marcela; García-Medina, Sandra; Razo-Estrada, Celene; Gómez-Oliván, Leobardo Manuel

    2010-01-01

    Diclofenac is a nonsteroidal anti-inflammatory drug widely used in Mexico where it is sold over the counter. It enters water bodies through municipal and industrial discharges, posing a risk to water systems and aquatic organisms. Diclofenac-enriched artificial sediment was used to evaluate the toxicity of this pharmaceutical on the sentinel species Hyalella azteca, using oxidative stress biomarkers in order to determine if the set of tests used in this study is a suitable early damage biomarker. The median lethal concentration (72-h LC(50)) was determined and oxidative stress was evaluated using lipid peroxidation, protein carbonyl content to evaluate oxidized protein content, and the activity of superoxide dismutase, catalase, and glutathione peroxidase. All biomarkers were significantly altered. Diclofenac induces oxidative stress in H. azteca and the set of tests used (lipid peroxidation, protein carbonyl content, antioxidant enzyme activities) constitutes an adequate early damage biomarker for evaluating the toxicity of this pharmaceutical group in aquatic species.

  6. Hyalella azteca (Saussure) responses to Coldwater River backwater sediments in Mississippi, USA.

    Science.gov (United States)

    Knight, Scott S; Lizotte, Richard E; Shields, F Douglas

    2009-10-01

    Sediment from three Coldwater River, Mississippi backwaters was examined using 28 day Hyalella azteca bioassays and chemical analyses for 33 pesticides, seven metals and seven PCB mixtures. Hydrologic connectivity between the main river channel and backwater varied widely among the three sites. Mortality occurred in the most highly connected backwater while growth impairment occurred in the other two. Precopulatory guarding behavior was not as sensitive as growth. Fourteen contaminants (seven metals, seven pesticides) were detected in sediments. Survival was associated with the organochlorine insecticide heptachlor.

  7. Acute dysprosium toxicity to Daphnia pulex and Hyalella azteca and development of the biotic ligand approach.

    Science.gov (United States)

    Vukov, Oliver; Smith, D Scott; McGeer, James C

    2016-01-01

    The toxicological understanding of rare earth elements (REEs) in the aquatic environment is very limited but of increasing concern. The objective of this research is to compare the toxicological effect of the REE dysprosium to the freshwater invertebrates Daphnia pulex and Hyalella azteca and in the more sensitive organism, understand the toxicity modifying influence of Ca, Na, Mg, pH and dissolved organic matter (DOM). Standard methods (Environment Canada) were followed for testing and culture in media of intermediate hardness (60mg CaCO3 mg/L) at pH 7.8 with Ca at 0.5, Na 0.5, Mg 0.125 (mM) and 23°C. Acute toxicity tests were done with azteca and D. pulex revealed Hyalella to be 1.4 times more sensitive than Daphnia. Additions of Ca and Na but not Mg provided significant protection against Dy toxicity to Hyalella. Similarly, low pH was associated with reduction in toxicity. Exposures which were pH buffered with and without MOPS were significantly different and indicated that MOPS enhanced Dy toxicity. DOM also mitigated Dy toxicity. Biotic ligand based parameters (LogK values) were calculated based on free ion relationships as determined by geochemical equilibrium modeling software (WHAM ver. 7.02). The logK value for Dy(3+) toxicity to Hyalella was 7.75 while the protective influence of Ca and Na were 3.95 and 4.10, respectively. This study contributes data towards the development of site specific water quality guidelines and criteria for Dy and possibly REEs in general and offers insight into the complex bio-geochemical nature of this element.

  8. Water-sediment interactions for Hyalella azteca exposed to uranium-spiked sediment

    Energy Technology Data Exchange (ETDEWEB)

    Alves, L.C. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Aquatic Ecosystems Protection Research Division, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada)], E-mail: Lara.Alves@ec.gc.ca; Borgmann, U. [Aquatic Ecosystems Protection Research Division, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada); Dixon, D.G. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada)

    2008-05-01

    Data on the toxicity of uranium in sediments to Hyalella azteca and the effect of overlying water chemistry are limited. This study exposed H. azteca to sediments spiked with U (0-10,000 {mu}g U/g dry weight) and five different overlying waters, which varied independently in hardness and alkalinity. Water pH had a major effect on U bioavailability and uptake by H. azteca. Uranium toxicity was higher when overlying water pH was low, while desorption of U into the overlying water increased with increasing pH. There appears to be little effect of Ca on U uptake, other than its influence on U speciation. Experiments with caged animals indicate that U accumulation and toxicity occur mainly through the dissolved phase rather than the solid phase. Uranium bioaccumulation is a more reliable indicator of U toxicity than U concentration in water or sediment. Uranium bioaccumulation in the H. azteca and U adsorption to sediment can be satisfactorily explained using saturation models.

  9. Testing Local Adaptation in Five Populations of Hyalella azteca in Northern Alberta's Oil Sands Region.

    Science.gov (United States)

    Beery, Steven R; Gauthier, Patrick T; Pyle, Gregory G

    2017-02-01

    Canada's oil sands hold the third largest petroleum reserves worldwide and have experienced rapid economic growth. The oil sands region provides an ideal location for studying local adaptations through reciprocal transplant (RT) because populations within the region have been historically exposed to naturally occurring bitumen. Our objectives were to (1) determine if Hyalella azteca from habitats within the oil sands region exhibited increased tolerance to constituents associated with industrial bitumen extraction compared with H. azteca from habitats outside the region; and (2) determine if any observed tolerance was attributable to local adaptation. Five populations of H. azteca were reciprocally transplanted from reclaimed and reference wetlands: four from local wetlands plus one naïve laboratory population. Survival, toxicity, and behaviour were measured before and after the RT period. Survival varied by population and site. These results show that the differences in responses among populations are likely not attributable to local adaptation and that laboratory populations of H. azteca provide ecologically relevant results when tested in the field.

  10. Water-sediment interactions for Hyalella azteca exposed to uranium-spiked sediment.

    Science.gov (United States)

    Alves, L C; Borgmann, U; Dixon, D G

    2008-05-01

    Data on the toxicity of uranium in sediments to Hyalella azteca and the effect of overlying water chemistry are limited. This study exposed H. azteca to sediments spiked with U (0-10,000 microg U/g dry weight) and five different overlying waters, which varied independently in hardness and alkalinity. Water pH had a major effect on U bioavailability and uptake by H. azteca. Uranium toxicity was higher when overlying water pH was low, while desorption of U into the overlying water increased with increasing pH. There appears to be little effect of Ca on U uptake, other than its influence on U speciation. Experiments with caged animals indicate that U accumulation and toxicity occur mainly through the dissolved phase rather than the solid phase. Uranium bioaccumulation is a more reliable indicator of U toxicity than U concentration in water or sediment. Uranium bioaccumulation in the H. azteca and U adsorption to sediment can be satisfactorily explained using saturation models.

  11. Agricultural pesticides in Mississippi Delta oxbow lake sediments during autumn and their effects on Hyalella azteca.

    Science.gov (United States)

    Lizotte, Richard E; Knight, Scott S; Bryant, Charles T; Smith, Sammie

    2009-10-01

    Agricultural pesticide contamination of sediments from five Mississippi Delta oxbow lakes and their effects and bioavailablity to Hyalella azteca were assessed during a low-application season-autumn. Three reference oxbow lakes were located in the White River National Wildlife Refuge (WRNWR), Arkansas and two impaired lakes, according to the US Environmental Agency Sect. 303 (d) Clean Water Act, were located in Mississippi. Surface sediment (top 5 cm) was collected at three sites within each lake and analyzed for 17 current and historic-use pesticides and metabolites. Chronic 28-day H. azteca sediment bioassays and pesticide body residue analyses were completed to determine the degree of biological responses and bioavailability. The greatest number of detectable pesticides in WRNWR and 303 (d) sediment samples was 9 and 12, respectively, with historic-use pesticide metabolite, p,p'-DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] ubiquitous. No significant (p > 0.05) differences in animal survival were observed among sites. Animal growth was significantly (p azteca with current-use pesticides detected at three sites; historic-use pesticides and metabolites detected at 11 sites. Animal body residues of a historic-use pesticide (dieldrin) and metabolite (p,p'-DDE) were associated with observed growth responses. Results show limited current-use pesticide contamination of sediments and H. azteca body tissues during autumn and that historic-use pesticides and metabolites are the primary contributors to observed biological responses.

  12. Influence of chloride on the chronic toxicity of sodium nitrate to Ceriodaphnia dubia and Hyalella azteca.

    Science.gov (United States)

    Soucek, David J; Dickinson, Amy

    2016-09-01

    While it has been well established that increasing chloride concentration in water reduces the toxicity of nitrite to freshwater species, little work has been done to investigate the effect of chloride on nitrate toxicity. We conducted acute and chronic nitrate (as sodium nitrate) toxicity tests with the cladoceran Ceriodaphnia dubia and the amphipod Hyalella azteca (chronic tests only) over a range of chloride concentrations spanning natural chloride levels found in surface waters representative of watersheds of the Great Lakes Region. Chronic nitrate toxicity test results with both crustaceans were variable, with H. azteca appearing to be one of the more sensitive invertebrate species tested and C. dubia being less sensitive. While the variability in results for H. azteca were to an extent related to chloride concentration in test water that was distinctly not the case for C. dubia. We concluded that the chloride dependent toxicity of nitrate is not universal among freshwater crustaceans. An additional sodium chloride chronic toxicity test with the US Lab strain of H. azteca in the present study suggested that when present as predominantly sodium chloride and with relatively low concentrations of other ions, there is a narrow range of chloride concentrations over which this strain is most fit, and within which toxicity test data are reliable.

  13. Pairing behaviour and reproduction in Hyalella azteca as sensitive endpoints for detecting long-term consequences of pesticide pulses

    DEFF Research Database (Denmark)

    Pedersen, Signe; Palmqvist, Annemette; Thorbek, Pernille

    2013-01-01

    The aim of the present study was to examine acute and delayed effects of pulse exposure of the pyrethroid pesticide, permethrin, on precopulatory pairs of Hyalella azteca. Pairs of H. azteca were exposed to a single 1 h pulse of different nominal concentrations of permethrin: 0, 0.3, 0.9 or 2.7 μg....../L, but not 0.3 μg/L, compared to the control groups. The long-term effects of short-term exposure on reproductive behavior of pairs could potentially have consequences for the population dynamics of H. azteca. However, since individual-level responses can both overestimate and underestimate effects...

  14. Interlaboratory testing of 42-d Hyalella azteca survival, growth and reproduction method with sediment and water-only exposures

    Science.gov (United States)

    Over the past four years, USEPA-Duluth, USGS-Columbia, the Illinois Natural History Survey, and Environment Canada have conducted studies to refine the USEPA/ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with Hyalella azteca. In advanc...

  15. Evaluation of the Influence of Bromide or Iodide on the Performance the Amphipod Hyalella azteca in Reconstituted Waters

    Science.gov (United States)

    Survival, growth, or reproduction of the amphipod Hyalella azteca (HA) is reported to be poor when some reconstituted waters have been used to conduct chronic (>14-d) water-only or sediment toxicity tests, including ASTM reconstituted hard water (with no addition of Bromi...

  16. Influence of selected water quality characteristics on the toxicity of lambda-cyhalothrin and gamma-cyhalothrin to Hyalella azteca

    Science.gov (United States)

    This study was conducted to assess the influence of suspended solids, dissolved organic carbon, and phytoplankton (as chlorophyll a) water quality characteristics on lambda-cyhalothrin and gamma-cyhalothrin aqueous toxicity to Hyalella azteca using natural water from 12 ponds and lakes in Mississipp...

  17. Evaluation of the Influence of Bromide or Iodide on the Performance the Amphipod Hyalella azteca in Reconstituted Waters

    Science.gov (United States)

    Survival, growth, or reproduction of the amphipod Hyalella azteca (HA) is reported to be poor when some reconstituted waters have been used to conduct chronic (>14-d) water-only or sediment toxicity tests, including ASTM reconstituted hard water (with no addition of Bromi...

  18. Interlaboratory testing of 42-d Hyalella azteca survival, growth and reproduction method with sediment and water-only exposures

    Science.gov (United States)

    Over the past four years, USEPA-Duluth, USGS-Columbia, the Illinois Natural History Survey, and Environment Canada have conducted studies to refine the USEPA/ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with Hyalella azteca. In advanc...

  19. An assessment of Hyalella azteca burrowing activity under laboratory sediment toxicity testing conditions.

    Science.gov (United States)

    Doig, Lorne E; Liber, Karsten

    2010-09-01

    Burrowing of the freshwater amphipod Hyalella azteca was evaluated under laboratory conditions similar to those recommended for standard sediment toxicity testing in Canada (EPS 1/RM/33; Environment Canada, 1997) and the United States (EPA/600/R-99/064; US EPA, 2000). Sediment type, time of day (light versus dark), size of animal, and the presence or absence of food were varied to assess their effects on burrowing activity. Hyalella azteca were found to burrow rapidly in fine, organic-rich sediments, but were slower to burrow in a sandy sediment. There was no increase in the number of animals occupying the sediment surface of a fine, organic-rich sediment after 4h of darkness compared to the previous 4h of light. Over a 9- to 10-d duration, a higher percentage of animals occupied the surface of the sandy sediment. The addition of food promoted burrowing in sandy sediment, as did using smaller animals. Overall, longer-duration tests involving older animals and coarse sediments may require formal observation to confirm burrowing and ensure adequate sediment exposure. The addition of food during a test may promote the burrowing of larger animals in coarse sediments, but may not be necessary in field-collected sediments that are not excessively sandy.

  20. Assessment of the effect of water quality on copper toxicity in Hyalella azteca

    Energy Technology Data Exchange (ETDEWEB)

    Richards, L. [Univ. of Guelph, Guelph, Ontario (Canada); Walsh, S.; Shultz, C.; Stuart, M. [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada)

    2015-06-15

    The objective of this study was to test the hypothesis that when standard artificial media 5-salt culture water (SAM-5S) is used to test sediment toxicity of much lower ionic-strength aquatic ecosystems, the resulting toxicity estimates are lower than if the tests had been conducted in water of comparable ionic strength. Results showed that this concern was unfounded for testing of copper toxicity to Hyalella azteca (H. azteca) in Ottawa River water. Sediment testing is often conducted using a standard water that is prepared in the laboratory. However, this water may have an ionic strength that is different than local water bodies. It follows that laboratory results using the standard water may be unrepresentative. A study was undertaken to assess the copper tolerance of 2 strains of H. azteca in SAM-5S, diluted SAM-5S (similar in electrical conductivity to Ottawa River water), and Ottawa River water. Acute (96 h) copper toxicity tests were conducted with 9-16 day-old H. azteca. For a given water type, the 2 strains of H. azteca yielded comparable responses to copper. The highest copper tolerance was found in Ottawa River water (closely followed by SAM-5S), whereas the lowest copper tolerance was found in diluted SAM-5S. Our results suggest that sediment toxicity is not lowered by the higher ionic strength of SAM-5S and that sediment toxicity tests of Ottawa River sediments, conducted with SAM-5S, can be used to estimate the in situ toxicity of the sediments. (author)

  1. Chronic toxicity of the synthetic hormone 17alpha-ethinylestradiol to Chironomus tentans and Hyalella azteca.

    Science.gov (United States)

    Dussault, Eve B; Balakrishnan, Vimal K; Solomon, Keith R; Sibley, Paul K

    2008-12-01

    The chronic toxicity of the synthetic hormone 17alpha-ethinylestradiol (EE2) was investigated in two benthic invertebrates, the midge Chironomus tentans and the freshwater amphipod Hyalella azteca, in life-cycle water-only assays. In C. tentans, a 50% decrease in emergence was observed at a concentration of 1.5 mg/L; emergence was a more sensitive endpoint than survival, growth, or biomass. Reproduction was not significantly affected by EE2 exposure until a concentration of 3.1 mg/L, where emergence, and therefore reproduction, did not occur. In contrast, reproduction was the most sensitive endpoint in H. azteca (50% decrease in reproduction observed at a concentration of 0.36 mg/L). The sensitivity of the F1 generation to EE2 was also investigated with H. azteca, but was not different from the F0 generation. The data from the present study were combined with those from previous 10-d toxicity assays, to derive acute to chronic toxicity ratios (ACRs) for EE2. The ACRs calculated for EE2 were 13 for C. tentans and 16 for H. azteca, indicating that the application factors currently used in ecological risk assessment for the derivation of chronic toxicity are protective and conservative for these organisms. The results of the present study suggest that chronic toxicity was not mediated by disruption of endocrine pathways. Using a hazard quotient approach, the risk associated with sublethal exposure to EE2 was azteca and C. tentans, indicating that adverse effects are not expected, and that environmental exposure to EE2 likely poses a low risk to benthic invertebrates.

  2. Acute dysprosium toxicity to Daphnia pulex and Hyalella azteca and development of the biotic ligand approach

    Energy Technology Data Exchange (ETDEWEB)

    Vukov, Oliver, E-mail: vuko3930@mylaurier.ca [Biology Department, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5 (Canada); Smith, D. Scott [Chemistry Department, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5 (Canada); McGeer, James C. [Biology Department, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5 (Canada)

    2016-01-15

    The toxicological understanding of rare earth elements (REEs) in the aquatic environment is very limited but of increasing concern. The objective of this research is to compare the toxicological effect of the REE dysprosium to the freshwater invertebrates Daphnia pulex and Hyalella azteca and in the more sensitive organism, understand the toxicity modifying influence of Ca, Na, Mg, pH and dissolved organic matter (DOM). Standard methods (Environment Canada) were followed for testing and culture in media of intermediate hardness (60 mg CaCO{sub 3} mg/L) at pH 7.8 with Ca at 0.5, Na 0.5, Mg 0.125 (mM) and 23 °C. Acute toxicity tests were done with <24 h old neonates for 48 h in the case of D. pulex and with 2–9 days old offspring for 96 h tests with Hyalella. The potential protective effect of cationic competition was tested with Ca (0.5–2.0 mM), Na (0.5–2.0 mM) and Mg (0.125–0.5 mM). The effect of pH (6.5–8.0) and Suwannee River DOM complexation (at dissolved organic carbon (DOC) concentrations of 9 and 13 mg C/L) were evaluated. Dissolved Dy concentrations were lower than total (unfiltered) indicating precipitation, particularly at higher concentrations. Acute toxicity of Dy to H. azteca and D. pulex revealed Hyalella to be 1.4 times more sensitive than Daphnia. Additions of Ca and Na but not Mg provided significant protection against Dy toxicity to Hyalella. Similarly, low pH was associated with reduction in toxicity. Exposures which were pH buffered with and without MOPS were significantly different and indicated that MOPS enhanced Dy toxicity. DOM also mitigated Dy toxicity. Biotic ligand based parameters (Log K values) were calculated based on free ion relationships as determined by geochemical equilibrium modeling software (WHAM ver. 7.02). The log K value for Dy{sup 3+} toxicity to Hyalella was 7.75 while the protective influence of Ca and Na were 3.95 and 4.10, respectively. This study contributes data towards the development of site specific

  3. Effect of test duration and feeding on relative sensitivity of genetically distinct clades of Hyalella azteca.

    Science.gov (United States)

    Soucek, David J; Dickinson, Amy; Major, Kaley M; McEwen, Abigail R

    2013-11-01

    The amphipod Hyalella azteca is widely used in ecotoxicology laboratories for the assessment of chemical risks to aquatic environments, and it is a cryptic species complex with a number of genetically distinct strains found in wild populations. While it would be valuable to note differences in contaminant sensitivity among different strains collected from various field sites, those findings would be influenced by acclimation of the populations to local conditions. In addition, potential differences in metabolism or lipid storage among different strains may confound assessment of sensitivity in unfed acute toxicity tests. In the present study, our aim was to assess whether there are genetic differences in contaminant sensitivity among three cryptic provisional species of H. azteca. Therefore, we used organisms cultured under the same conditions, assessed their ability to survive for extended periods without food, and conducted fed and unfed acute toxicity tests with two anions (nitrate and chloride) whose toxicities are not expected to be altered by the addition of food. We found that the three genetically distinct clades of H. azteca had substantially different responses to starvation, and the presence/absence of food during acute toxicity tests had a strong role in determining the relative sensitivity of the three clades. In fed tests, where starvation was no longer a potential stressor, significant differences in sensitivity were still observed among the three clades. In light of these differences in sensitivity, we suggest that ecotoxicology laboratories consider using a provisional species in toxicity tests that is a regionally appropriate surrogate.

  4. Role of vegetation in a constructed wetland on nutrient-pesticide mixture toxicity to Hyalella azteca.

    Science.gov (United States)

    Lizotte, Richard E; Moore, Matthew T; Locke, Martin A; Kröger, Robert

    2011-02-01

    The toxicity of a nutrient-pesticide mixture in nonvegetated and vegetated sections of a constructed wetland (882 m² each) was assessed using Hyalella azteca 48-h aqueous whole-effluent toxicity bioassays. Both sections were amended with a mixture of sodium nitrate, triple superphosphate, diazinon, and permethrin simulating storm-event agricultural runoff. Aqueous samples were collected at inflow, middle, and outflow points within each section 5 h, 24 h, 72 h, 7 days, 14 days, and 21 days postamendment. Nutrients and pesticides were detected throughout both wetland sections with concentrations longitudinally decreasing more in vegetated than nonvegetated section within 24 h. Survival effluent dilution point estimates-NOECs, LOECs, and LC₅₀s-indicated greatest differences in toxicity between nonvegetated and vegetated sections at 5 h. Associations of nutrient and pesticide concentrations with NOECs indicated that earlier toxicity (5-72 h) was from permethrin and diazinon, whereas later toxicity (7-21 days) was primarily from diazinon. Nutrient-pesticide mixture concentration-response assessment using toxic unit models indicated that H. azteca toxicity was due primarily to the pesticides diazinon and permethrin. Results show that the effects of vegetation versus no vegetation on nutrient-pesticide mixture toxicity are not evident after 5 h and a 21-day retention time is necessary to improve H. azteca survival to ≥90% in constructed wetlands of this size.

  5. Time-dependent lethal body residues for the toxicity of pentachlorobenzene to Hyalella azteca

    Science.gov (United States)

    Landrum, Peter F.; Steevens, Jeffery A.; Gossiaux, Duane C.; McElroy, Michael; Robinson, Sander; Begnoche, Linda; Chernyak, Sergei; Hickey, James

    2004-01-01

    The study examined the temporal response of Hyalella azteca to pentachlorobenzene (PCBZ) in water-only exposures. Toxicity was evaluated by calculating the body residue of PCBZ associated with survival. The concentration of PCBZ in the tissues of H. azteca associated with 50% mortality decreased from 3 to 0.5 μmol/g over the temporal range of 1 to 28 d, respectively. No significant difference was observed in the body residue calculated for 50% mortality when the value was determined using live or dead organisms. Metabolism of PCBZ was not responsible for the temporal response because no detectable PCBZ biotransformation occurred over an exposure period of 10 d. A damage assessment model was used to evaluate the impact and repair of damage by PCBZ on H. azteca. The toxicokinetics were determined so that the temporal toxicity data could be fit to a damage assessment model. The half-life calculated for the elimination of PCBZ averaged approximately 49 h, while the value determined for the half-life of damage repair from the damage assessment model was 33 h.

  6. The amphipod Hyalella azteca as a biomonitor in field deployment studies for metal mining.

    Science.gov (United States)

    Couillard, Y; Grapentine, L C; Borgmann, U; Doyle, P; Masson, S

    2008-12-01

    Specimens of the amphipod Hyalella azteca were deployed, in June-July 2003, along metal contamination gradients in two rivers affected by metal mining in the Abitibi-James Bay region, northwestern Québec. The amphipods were placed along with natural food items in small, acrylic cages and left in six riverine sites for 17 days. Twelve metals (As, Cu, La, Mn, Ni, Sb, Se, Tl, U, V, Zn, and CrO4(2-) modelled by WHAM VI) in transplanted H. azteca varied along metal contamination gradients in a consistent manner, i.e., as a function of metal exposure. Bioaccumulation of As, Cr, La, Ni, Sb, Se, Tl, U and V, as defined by a field BCF, was significantly correlated with their chronic toxicity potential towards the amphipod. We conclude that H. azteca may be a useful field biomonitor for metal mining. In addition, our results suggest that such biomonitoring programs should include less studied elements such as Se in mining effluents.

  7. Response spectrum of pentachlorobenzene and fluoranthene for Chironomus tentans and Hyalella azteca.

    Science.gov (United States)

    Schuler, Lance J; Landrum, Peter F; Lydy, Michael J

    2007-06-01

    The whole-body residues of pentachlorobenzene (PCBz) and fluoranthene (FLU) in Hyalella azteca and Chironomus tentans were determined for a variety of chronic sublethal effects. The endpoints evaluated for H. azteca included 28-d growth and survival and 42-d growth, survival, and reproduction. Adverse effects to C. tentans also were determined at multiple endpoints including 10-d growth, cumulative pupation and emergence, and reproduction. The lowest-observed-effect residue (LOER) based on whole-body residues associated with growth was consistent between compounds and species tested with concentrations ranging from 0.17 to 0.33 micromol/g. For H. azteca, the most sensitive endpoints were growth at 0.23 micromol/g and reproduction at 0.11 micromol/g for PCBz and FLU, respectively. For C. tentans, the most sensitive endpoints were emergence, development and reproduction at 0.02 micromol/g, and development and reproduction at 0.15 micromol/g for PCBz and FLU, respectively. Compared to residues associated with acute lethality, the most sensitive sublethal endpoints were approximately 4 and 60 times lower for PCBz and FLU, respectively. The relative consistency of the sublethal endpoints suggests that body residues can be a valuable tool to evaluate bioaccumulation data as part of a risk assessment to predict adverse effects to biota.

  8. Kinetics of uranium uptake in soft water and the effect of body size, bioaccumulation and toxicity to Hyalella azteca

    Energy Technology Data Exchange (ETDEWEB)

    Alves, L.C. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Aquatic Ecosystems Protection Research Division, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada); Borgmann, U. [Aquatic Ecosystems Protection Research Division, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada); Dixon, D.G., E-mail: dgdixon@uwaterloo.c [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada)

    2009-08-15

    The kinetics of uptake and the effect of body size on uranium (U) bioaccumulation and toxicity to Hyalella azteca exposed to water-only U concentrations in soft water were evaluated. The effect of body size on U bioaccumulation was significant with a slope of -0.35 between log body concentration and log body mass. A saturation kinetic model was satisfactory to describe the uptake rate, elimination rate and the effect of gut-clearance on size-corrected U bioaccumulation in H. azteca. The one-week lethal water concentrations causing 50% mortality for juvenile and adult H. azteca were 1100 and 4000 nmol U/L, respectively. The one-week lethal body concentration causing 50% mortality was 140 nmol U/g for juvenile H. azteca and 220 nmol U/g for adult H. azteca. One-week bioaccumulation studies that properly account for body-size and gut-clearance times can provide valuable data on U bioavailability and toxicity in the environment. - Uranium accumulation by Hyalella azteca approaches steady state after one week but is strongly dependent on body size.

  9. Effect of diet quality on chronic toxicity of aqueous lead to the amphipod Hyalella azteca.

    Science.gov (United States)

    Besser, John M; Ivey, Chris D; Brumbaugh, William G; Ingersoll, Christopher G

    2016-07-01

    The authors investigated the chronic toxicity of aqueous Pb to the amphipod Hyalella azteca (Hyalella) in 42-d tests using 2 different diets: 1) the yeast + cereal leaf + trout pellet (YCT) diet, fed at the uniform low ration used in standard methods for sediment toxicity tests; and 2) a new diet of diatoms + TetraMin flakes (DT), fed at increasing rations over time, that has been optimized for use in Hyalella water-only tests. Test endpoints included survival, weight, biomass, fecundity, and total young. Lethal effects of Pb were similar for the DT and YCT tests (20% lethal concentration [LC20] = 13 μg/L and 15 μg/L, respectively, as filterable Pb). In contrast, weight and fecundity endpoints were not significantly affected in the DT test at Pb concentrations up to 63 µg/L, but these endpoints were significantly reduced by Pb in the YCT test-and in a 2005 test in the same laboratory with a diet of conditioned Rabbit Chow (RC-2005). The fecundity and total young endpoints from the YCT and RC-2005 tests were considered unreliable because fecundity in controls did not meet test acceptability criteria, but both of these tests still produced lower Pb effect concentrations (for weight or biomass) than the test with the DT diet. The lowest biotic ligand model-normalized effect concentrations for the 3 tests ranged from 3.7 μg/L (weight 20% effect concentration [EC20] for the RC-2005 test) to 8.2 μg/L (total young EC20 for the DT test), values that would rank Hyalella as the second or third most sensitive of 13 genera in a species sensitivity distribution for chronic Pb toxicity. These results demonstrate that toxicity tests with Hyalella fed optimal diets can meet more stringent test acceptability criteria for control performance, but suggest that results of these tests may underestimate sublethal toxic effects of Pb to Hyalella under suboptimal feeding regimes. Environ Toxicol Chem 2016;35:1825-1834. Published 2015 Wiley Periodicals Inc

  10. Effect of diet quality on chronic toxicity of aqueous lead to the amphipod Hyalella azteca

    Science.gov (United States)

    Besser, John M.; Ivey, Chris D.; Brumbaugh, William G.; Ingersoll, Christopher G.

    2016-01-01

    The authors investigated the chronic toxicity of aqueous Pb to the amphipod Hyalella azteca (Hyalella) in 42-d tests using 2 different diets: 1) the yeastþcereal leafþtrout pellet (YCT) diet, fed at the uniform low ration used in standard methods for sediment toxicity tests; and 2) a new diet of diatomsþTetraMin flakes (DT), fed at increasing rations over time, that has been optimized for use in Hyalella water-only tests. Test endpoints included survival, weight, biomass, fecundity, and total young. Lethal effects of Pb were similar for the DT and YCT tests (20% lethal concentration [LC20]¼13 mg/L and 15mg/L, respectively, as filterable Pb). In contrast, weight and fecundity endpoints were not significantly affected in the DT test at Pb concentrations up to 63 mg/L, but these endpoints were significantly reduced by Pb in the YCT test—and in a 2005 test in the same laboratory with a diet of conditioned Rabbit Chow (RC-2005). The fecundity and total young endpoints from the YCT and RC-2005 tests were considered unreliable because fecundity in controls did not meet test acceptability criteria, but both of these tests still produced lower Pb effect concentrations (for weight or biomass) than the test with the DT diet. The lowest biotic ligand model–normalized effect concentrations for the 3 tests ranged from 3.7mg/L (weight 20% effect concentration [EC20] for the RC-2005 test) to 8.2 mg/L (total young EC20 for the DT test), values that would rank Hyalella as the second or third most sensitive of 13 genera in a species sensitivity distribution for chronic Pb toxicity. These results demonstrate that toxicity tests with Hyalella fed optimal diets can meet more stringent test acceptability criteria for control performance, but suggest that results of these tests may underestimate sublethal toxic effects of Pb to Hyalella under suboptimal feeding regimes.

  11. Use of sublethal endpoints in sediment toxicity tests with the amphipod Hyalella azteca

    Science.gov (United States)

    Ingersoll, Chris G.; Brunson, Eric L.; Dwyer, F. James; Hardesty, Douglas K.; Kemble, Nile E.

    1998-01-01

    Short-term sediment toxicity tests that only measure effects on survival can be used to identify high levels of contamination but may not be able to identify marginally contaminated sediments. The objective of the present study was to develop a method for determining the potential sublethal effects of contaminants associated with sediment on the amphipod Hyalella azteca (e.g., reproduction). Exposures to sediment were started with 7- to 8-d-old amphipods. On day 28, amphipods were isolated from the sediment and placed in water-only chambers where reproduction was measured on day 35 and 42. Typically, amphipods were first in amplexus at about day 21 to 28 with release of the first brood between day 28 to 42. Endpoints measured included survival (day 28, 35, and 42), growth (as length and weight on day 28 and 42), and reproduction (number of young/female produced from day 28 to 42). This method was used to evaluate a formulated sediment and field-collected sediments with low to moderate concentrations of contaminants. Survival of amphipods in these sediments was typically >85% after the 28-d sediment exposures and the 14-d holding period in water to measure reproduction. Reproduction was more variable than growth; hence, more replicates might be needed to establish statistical differences among treatments. Previous studies have demonstrated that growth of H. azteca in sediment tests often provides unique information that can be used to discriminate toxic effects of exposure to contaminants. Either length or weight can be measured in sediment tests with H. azteca. However, additional statistical options are available if length is measured on individual amphipods, such as nested analysis of variance that can account for variance in length within replicates. Ongoing water-only studies testing select contaminants will provide additional data on the relative sensitivity and variability of sublethal endpoints in toxicity tests with H. azteca.

  12. A simple control for sediment-toxicity exposures using the amphipod, Hyalella azteca.

    Science.gov (United States)

    Lasier, Peter J; Urich, Matthew L

    2014-09-01

    Sediment-toxicity exposures comparing survival and growth of the freshwater amphipod, Hyalella azteca, are often components of aquatic-habitat assessments. Standardized exposure methods have been established and require evaluations for quality assurance. Test acceptability using performance-based criteria can be determined from exposures to control sediments, which are collected from the environment or formulated from commercially available components. Amending sand with leached alfalfa solids provided a simple formulated sediment that elicited consistently acceptable survival and growth in 28-day exposures with and without a daily feeding regime. A procedure is described for preparing the sediment along with results from comparisons among sand, amended sand, and field-collected sediments that incorporated three feeding regimes.

  13. Synergistic effect of piperonyl butoxide on acute toxicity of pyrethrins to Hyalella azteca.

    Science.gov (United States)

    Giddings, Jeffrey; Gagne, James; Sharp, Janice

    2016-08-01

    A series of acute toxicity tests with the amphipod Hyalella azteca was performed to quantify the synergistic effect of piperonyl butoxide (PBO) on pyrethrin toxicity. Concentrations of PBO <4 µg/L caused no toxicity enhancement, whereas toxicity increased with PBO concentrations between 4 µg/L and 15 µg/L. Additive toxicity calculations showed that true synergism accounted for an increase in pyrethrin toxicity (decrease in median lethal concentration) of 1.4-fold to 1.6-fold and varied only slightly between 4 µg/L and 15 µg/L PBO, whereas direct toxicity of PBO accounted for an additional increase in mixture toxicity (up to 3.2-fold) that was proportional to PBO concentration. The results can be used to assess the risk of measured or predicted co-occurring concentrations of PBO and pyrethrins in surface waters. Environ Toxicol Chem 2016;35:2111-2116. © 2016 SETAC.

  14. Effects of depleted uranium on the health and survival of Ceriodaphnia dubia and Hyalella azteca

    Science.gov (United States)

    Kuhne, W.W.; Caldwell, C.A.; Gould, W.R.; Fresquez, P.R.; Finger, S.

    2002-01-01

    Depleted uranium (DU) has been used as a substitute for the fissionable enriched uranium component of atomic weapons tested at Los Alamos National Laboratory (LANL) (Los Alamos, NM, USA) since the early 1950s, resulting in considerable concentrations of DU in the soils within the test sites. Although the movement of DU into major aquatic systems has been shown to be minimal, there are many small-order ephemeral streams and areas of standing water in canyons throughout LANL that may be affected by inputs of DU via runoff, erosion, and leaching. Ninety-six-hour acute and 7-d chronic toxicity assays were conducted to measure the toxicity of DU on survival and reproduction of Ceriodaphnia dubia. A 14-d water-only assay was conducted to measure survival and growth of Hyalella azteca. The estimated median lethal concentration (LC50) to produce 50% mortality of the test population for the 96-h Ceriodaphnia dubia assay was 10.50 mg/L. Reproductive effects occurred at a lowest-observable-effect concentration ???3.91 mg/L with a no-observable-effect concentration of 1.97 mg/L. The estimated 14-d LC50 for the Hyalella azteca assay was 1.52 mg/L No significant relationship was detected between growth and DU concentrations. Concentrations at which toxicity effects were observed in this study for both invertebrates exceeded concentrations of total uranium observed in runoff from LANL lands. Thus, it is likely that current runoff levels of uranium do not pose a threat to these types of aquatic invertebrates.

  15. Effect of gut clearance on metal body concentrations in Hyalella azteca

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, P.T.M.; Borgmann, U.; Norwood, W. [Environment Canada, Burlington, Ontario (Canada)

    1999-05-01

    Gut content can contribute significantly to the metal body burdens in sediment-exposed Hyalella azteca even if it has no direct effect on toxicity. To determine the duration and the effect of gut clearance on total body concentrations, the authors exposed H. azteca for 1 week to a spiked sediment (lead, cadmium, zinc, and copper); a second set of amphipods was kept in cages above the sediment. Following transfer into clean water (25 C) for 96 h, lead and zinc concentrations showed a biphasic decline, with a stronger decrease in the first 4 to 6 h, when gut clearance contributes significantly to metal loss. After 6 h, metal loss was apparently due to excretion from the body. Without gut clearance, the body concentrations of lead and zinc in sediment-exposed amphipods were overestimated by 438 and 44%, respectively. Gut clearance did not have a visible effect on cadmium and copper body burdens because the body and sediment concentrations were similar. After a depuration time of 6 h, direct excretion from the body resulted in a drop of less than 10% in the total body burdens of lead, cadmium, zinc, and copper compared to the gut-corrected time-zero body burdens. After 24 h, this loss increased up to 27%. Feeding during the depuration period did not have a significant influence on gut clearance. A model that allows estimation of the influence of gut content on the total body concentration of undepurated invertebrates from the bioconcentration factor is evaluated.

  16. Genotype and toxicity relationships among Hyalella azteca: II. Acute exposure to fluoranthene-contaminated sediment

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Y.; Guttman, S.I.; Oris, J.T.; Huang, X.; Burton, G.A.

    2000-05-01

    This study examined the genotypic responses of Hyalella azteca to the toxicity of sediment contaminated by the polycyclic aromatic hydrocarbon (PAH) fluoranthene. The authors monitored the time to death for 696 H. azteca exposed to ultraviolet light and sediment spiked with fluoranthene. The survival distribution functions within the genotypes at each of these variable allozyme loci (acid phosphatase [ACP*], glucose-6-phosphate isomerase [GPI*], and phosphoglucomutase [PGM*]) were compared using a long-rank test. Results showed significant differences among SDFs at all three loci. No association of heterozygosity with time to death was observed. The homozygote ACP*-CC was associated with decreased survivorship compared with ACP*-AA, ACP*-BB, and ACP*-AB. However, GPI*-AA was associated with increased survivorship compared with GPI*-BB, GPI*-CC, and GPI*-BC. Significant differences in resistance also were observed for PGM*-BB versus either PGM*-AC or PGM*-BC. These results indicate that differential resistance to PAH phototoxicity was genetically related, producing significant alteration in the frequencies of several genotypes in the population.

  17. Decamethylcyclopentasiloxane (D5) spiked sediment: bioaccumulation and toxicity to the benthic invertebrate Hyalella azteca.

    Science.gov (United States)

    Norwood, W P; Alaee, M; Sverko, E; Wang, D; Brown, M; Galicia, M

    2013-10-01

    Chronic toxicity and bioaccumulation of decamethylcyclopentasiloxane (D5) to Hyalella azteca was examined in a series of spiked sediment exposures. Juvenile H. azteca were exposed for 28d (chronic) to a concentration series of D5 in two natural sediments of differing organic carbon content (O.C.) and particle size composition. The chronic, LC50s were 191 and 857μgD5g(-1) dry weight for Lakes Erie (0.5% O.C.) and Restoule (11% O.C.) respectively. Inhibition of growth only occurred with the L. Restoule spiked sediment with a resultant EC25 of 821μgg(-1)dw. Lethality was a more sensitive endpoint than growth inhibition. Biota sediment accumulation factors (BSAFs, 28d) were <1 indicating that D5 did not bioconcentrate based on lipid normalized tissue concentrations and organic carbon normalized sediment concentrations. Organic carbon (OC) in the sediment appeared to be protective, however normalization to OC did not normalize the toxicity. Normalization of D5 concentrations in the sediments to sand content did normalize the toxicity and LC50 values of 3180 and 3570μg D5g(-1) sand dw were determined to be statistically the same.

  18. Influence of container adsorption upon observed pyrethroid toxicity to Ceriodaphnia dubia and Hyalella azteca

    Science.gov (United States)

    Wheelock, Craig E.; Miller, Jeff L.; Miller, Mike J.; Phillips, Bryn M.; Gee, Shirley J.; Tjeerdema, Ronald S.; Hammock, Bruce D.

    2006-01-01

    Pyrethroid insecticides are known for their potential toxicity to aquatic invertebrates and many fish species. A significant problem in the study of pyrethroid toxicity is their extreme hydrophobicity. They can adsorb to test container surfaces and many studies, therefore, report pyrethroid levels as nominal water concentrations. In this study, pyrethroid adsorption to sampling and test containers was measured and several container treatments were examined for their ability to decrease pyrethroid adsorption. None of the chemical treatments were successful at preventing pyrethroid loss from aqueous samples, but vortexing of containers served to resuspend pyrethroids. The effects of the observed adsorption on Ceriodaphnia dubia and Hyalella azteca permethrin toxicity were examined. Species-specific results showed a time-dependent decrease in toxicity following pyrethroid adsorption to test containers for C. dubia, but not for H. azteca. These results demonstrate that pyrethroid adsorption to containers can significantly affect the observed outcome in toxicity-testing and serves as a caution for researchers and testing laboratories. PMID:15951033

  19. Comparative sensitivity of field and laboratory populations of Hyalella azteca to the pyrethroid insecticides bifenthrin and cypermethrin.

    Science.gov (United States)

    Clark, Stephen L; Ogle, R Scott; Gantner, Andrew; Hall, Lenwood W; Mitchell, Gary; Giddings, Jeffrey; McCoole, Matthew; Dobbs, Michael; Henry, Kevin; Valenti, Ted

    2015-10-01

    Hyalella azteca are epibenthic invertebrates that are widely used for toxicity studies. They are reported to be more sensitive to pyrethroid insecticides than most other test species, which has prompted considerable use of this species in toxicity testing of ambient surface waters where the presence of pyrethroids is suspected. However, resident H. azteca have been found in some ambient water bodies reported to contain surface water and/or sediment pyrethroid concentrations that are toxic to laboratory reared H. azteca. This observation suggests differences in the sensitivities of laboratory reared and field populations of H. azteca to pyrethroids. The goal of the present study was to determine the sensitivities of laboratory reared and field populations of H. azteca to the pyrethroids bifenthrin and cypermethrin. Specimens of H. azteca were collected from resident populations at field sites that are subject to varied land-use activities as well as from laboratory populations. These organisms were exposed to bifenthrin- or cypermethrin-spiked water in 96-h water-only toxicity tests. The resulting data demonstrated that: 1) field-collected populations in urban and agricultural settings can be >2 orders of magnitude less sensitive to the pyrethroids than laboratory reared organisms; 2) field-collected organisms varied in their sensitivity (possibly based on land-use activities), with organisms collected from undeveloped sites exhibiting sensitivities similar to laboratory reared organisms; and 3) the sensitivity of field-collected "tolerant" organisms increased in subsequent generations reared under laboratory conditions. Potential mechanisms for these differences are discussed.

  20. The common ecotoxicology laboratory strain of Hyalella azteca is genetically distinct from most wild strains sampled in eastern North America.

    Science.gov (United States)

    Major, Kaley; Soucek, David J; Giordano, Rosanna; Wetzel, Mark J; Soto-Adames, Felipe

    2013-11-01

    The amphipod Hyalella azteca is commonly used as a model for determining safe concentrations of contaminants in freshwaters. The authors sequenced the mitochondrial cytochrome c oxidase subunit I (COI) gene for representatives of 38 populations of this species complex from US and Canadian toxicology research laboratories and eastern North American field sites to determine their genetic relationships. With 1 exception, all US and Canadian laboratory cultures sampled were identified as conspecific. In 22 wild populations spanning 5 US states and 1 Canadian province, the commonly occurring laboratory species was found only in northern Florida, USA. Therefore, the diversity of the H. azteca species complex detected in the wild is not accurately represented in North American laboratories, questioning the reliability of H. azteca cultures currently in use to accurately predict the responses of wild populations in ecotoxicological assays. The authors also examined the utility of different COI nucleotide fragments presently in use to determine phylogenetic relationships in this group and concluded that saturation in DNA sequences leads to inconsistent relationships between clades. Amino acid sequences for COI were not saturated and may allow a more accurate phylogeny estimate. Hyalella azteca is crucial for developing water-quality regulations; therefore, laboratories should know and standardize the strain(s) they use to confidently compare toxicity tests across laboratories and determine whether they are an appropriate surrogate for their regions.

  1. Toxicity Tests of Whole Sediment Samples Using the Hyallella (H. azteca) Survival and Growth Tests (ASTM E 1283-93)

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — 10-day toxicity tests using Hyalella azteca were conducted with sediment samples collected by the U.S. Fish & Wildlife Service, Bloomington, Indiana facility to...

  2. Single versus combined exposure of Hyalella azteca to zinc contaminated sediment and food.

    Science.gov (United States)

    Nguyen, Lien T H; Muyssen, Brita T A; Janssen, Colin R

    2012-03-01

    The amphipod Hyalella azteca was exposed for 28 d to different combinations of Zn contaminated sediment and food. Sediment exposure (+clean food) resulted in increased Zn body burdens, increased mortality and decreased body mass when the molar concentrations of simultaneously extracted Zn were greater than the molar concentration of Acid Volatile Sulfide (SEM(Zn)-AVS>0), suggesting that dissolved Zn was a dominant route of exposure. No adverse effect was noted in the food exposure (+clean sediment), suggesting selective feeding or regulation. Combined exposure (sediment+food) significantly increased adverse effects in comparison with sediment exposure, indicating contribution of dietary Zn to toxicity and bioaccumulation. The observed enhanced toxicity also supports the assumption on the presence of an avoidance/selective feeding reaction of the amphipods in the single sediment or food exposures. During 14 d post-exposure in clean medium, the organisms from the same combined exposure history received two feeding regimes, i.e. clean food and Zn spiked food. Elevated Zn bioaccumulation and reduced reproduction were noted in amphipods that were offered Zn spiked food compared to the respective organisms that were fed clean food. This was explained by the failure of avoidance/selective feeding behavior in the absence of an alternative food source (sediment), forcing the amphipods to take up Zn while feeding. Increasing Zn body burdens rejected the assumption that Zn uptake from food was regulated by H. azteca. Our results show that the selective feeding behavior should be accounted for when assessing ecological effects of Zn or other contaminants, especially when contaminated food is a potential exposure route.

  3. A field assessment of long-term laboratory sediment toxicity tests with the amphipod Hyalella azteca

    Science.gov (United States)

    Ingersoll, Christopher G.; Wang, Ning; Hayward, Jeannie M. R.; Jones, John R.; Jones, Susan B.; Ireland, D. Scott

    2005-01-01

    Response of the amphipod Hyalella azteca exposed to contaminated sediments for 10 to 42 d in laboratory toxicity tests was compared to responses observed in controlled three-month invertebrate colonization exposures conducted in a pond. Sediments evaluated included a sediment spiked with dichlorodiphenyldichloroethane (DDD) or dilutions of a field sediment collected from the Grand Calumet River (GCR) in Indiana (USA) (contaminated with organic compounds and metals). Consistent effects were observed at the highest exposure concentrations (400 ??g DDD/goc [DDD concentrations normalized to grams of organic carbon (goc) in sedimentl or 4% GCR sediment) on survival, length, and reproduction of amphipods in the laboratory and on abundance of invertebrates colonizing sediments in the field. Effect concentrations for DDD observed for 10-d length and 42-d reproduction of amphipods (e.g., chronic value [ChV] of 66 ??g DDD/goc and 25% inhibition concentration [IC25] of 68 ??g DDD/goc for reproduction) were similar to the lowest effect concentrations for DDD measured on invertebrates colonizing sediment the field. Effect concentrations for GCR sediment on 28-d survival and length and 42-d reproduction and length of amphipods (i.e., ChVs of 0.20-0.66% GCR sediment) provided more conservative effect concentrations compared to 10-d survival or length of amphipods in the laboratory or the response of invertebrates colonizing sediment in the field (e.g., ChVs of 2.2% GCR sediment). Results of this study indicate that use of chronic laboratory toxicity tests with H. azteca and benthic colonization studies should be used to provide conservative estimates of impacts on benthic communities exposed to contaminated sediments. Bioaccumulation of DDD by oligochaetes colonizing the DDD-spiked sediment was similar to results of laboratory sediment tests previously conducted with the oligochaete Lumbriculus variegates, confirming that laboratory exposures can be used to estimate

  4. Contrasting effects of chloride on growth, reproduction, and toxicant sensitivity in two genetically distinct strains of Hyalella azteca.

    Science.gov (United States)

    Soucek, David J; Mount, David R; Dickinson, Amy; Hockett, J Russell; McEwen, Abigail R

    2015-10-01

    The strain of Hyalella azteca (Saussure: Amphipoda) commonly used for aquatic toxicity testing in the United States has been shown to perform poorly in some standardized reconstituted waters frequently used for other test species. In 10-d and 42-d experiments, the growth and reproduction of the US laboratory strain of H. azteca was shown to vary strongly with chloride concentration in the test water, with declining performance observed below 15 mg/L to 20 mg/L. In contrast to the chloride-dependent performance of the US laboratory strain of H. azteca, growth of a genetically distinct strain of H. azteca obtained from an Environment Canada laboratory in Burlington, Ontario, Canada, was not influenced by chloride concentration. In acute toxicity tests with the US laboratory strain of H. azteca, the acute toxicity of sodium nitrate increased with decreasing chloride in a pattern similar not only to that observed for control growth, but also to previous acute toxicity testing with sodium sulfate. Subsequent testing with the Burlington strain showed no significant relationship between chloride concentration and the acute toxicity of sodium nitrate or sodium sulfate. These findings suggest that the chloride-dependent toxicity shown for the US laboratory strain may be an unusual feature of that strain and perhaps not broadly representative of aquatic organisms as a whole.

  5. Bioassays with caged hyalella azteca to determine in situ toxicity downstream of two Saskatchewan, Canada, uranium operations.

    Science.gov (United States)

    Robertson, Erin L; Liber, Karsten

    2007-11-01

    The main objectives of this in situ study were to evaluate the usefulness of an in situ bioassay to determine if downstream water bodies at the Key Lake and Rabbit Lake uranium operations (Saskatchewan, Canada) were toxic to Hyalella azteca and, if toxicity was observed, to differentiate between the contribution of surface water and sediment contamination to in situ toxicity. These objectives were achieved by performing 4-d in situ bioassays with laboratory-reared H. azteca confined in specially designed, paired, surface water and sediment exposure chambers. Results from the in situ bioassays revealed significant mortality, relative to the respective reference site, at the exposure sites at both Key Lake (p azteca at both operations, although this relationship was stronger at Key Lake. At Key Lake, the primary cause of aquatic toxicity to H. azteca did not appear to be correlated with the variables measured in this study, but most likely with a pulse of organic mill-process chemicals released during the time of the in situ study-a transient event that was caused by a problem with the mill's solvent extraction process. The suspected cause of in situ toxicity to H. azteca at Rabbit Lake was high levels of uranium in surface water, sediment, and pore water.

  6. Influence of dissolved organic matter on nickel bioavailability and toxicity to Hyalella azteca in water-only exposures.

    Science.gov (United States)

    Doig, Lorne E; Liber, Karsten

    2006-03-10

    Dissolved organic matter (DOM) is known to reduce the bioavailability of metals in aquatic systems. This study evaluated the effects of DOM from various sources (e.g., Little Bear Lake sediment, Suwannee River, peat moss) and various DOM fractions (humic acids, HA; fulvic acids, FA) on the bioavailability of nickel (Ni) to Hyalella azteca, a common freshwater benthic invertebrate. In particular, this study was conducted to evaluate the effect of surficial sediment DOM on Ni bioavailability. Short-term (48 h) acute toxicity tests with H. azteca conducted in synthetic water demonstrated that the aqueous Ni concentrations required for lethality were greater than what could be significantly complexed by environmentally relevant concentrations of dissolved organic carbon (DOC: 0.6-30.4 mg/L). At Ni concentrations sublethal to H. azteca (500 microg/L), the bioavailability of Ni was significantly reduced in the presence of representative surface water DOC concentrations regardless of DOC source or fraction. DOC fraction (i.e., FA and HA) differentially affected Ni speciation, but had little or no effect on Ni accumulation by H. azteca. Tissue Ni was found to be strongly dependent upon the Ni(2+) concentration in the exposure solutions and the Ni:DOC ratio. Overall, the concentration of DOC played a greater role than either DOC source or fraction in determining Ni speciation and hence bioavailability and toxicity to H. azteca.

  7. Kinetics of uranium uptake in soft water and the effect of body size, bioaccumulation and toxicity to Hyalella azteca.

    Science.gov (United States)

    Alves, L C; Borgmann, U; Dixon, D G

    2009-01-01

    The kinetics of uptake and the effect of body size on uranium (U) bioaccumulation and toxicity to Hyalella azteca exposed to water-only U concentrations in soft water were evaluated. The effect of body size on U bioaccumulation was significant with a slope of -0.35 between log body concentration and log body mass. A saturation kinetic model was satisfactory to describe the uptake rate, elimination rate and the effect of gut-clearance on size-corrected U bioaccumulation in H. azteca. The one-week lethal water concentrations causing 50% mortality for juvenile and adult H. azteca were 1100 and 4000 nmol U/L, respectively. The one-week lethal body concentration causing 50% mortality was 140 nmol U/g for juvenile H. azteca and 220 nmol U/g for adult H. azteca. One-week bioaccumulation studies that properly account for body-size and gut-clearance times can provide valuable data on U bioavailability and toxicity in the environment.

  8. Bioavailability-based toxicity endpoints of bifenthrin for Hyalella azteca and Chironomus dilutus.

    Science.gov (United States)

    Harwood, Amanda D; Landrum, Peter F; Lydy, Michael J

    2013-01-01

    Recent studies have determined that techniques, such as solid phase microextraction (SPME) fibers and Tenax beads, can predict bioaccumulation and potentially could predict toxicity for several compounds and species. Toxicity of bifenthrin was determined using two standard sediment toxicity tests with the benthic species Hyalella azteca and Chironomus dilutus in three reference sediments with different characteristics. The objectives of the current study were to establish bioavailability-based median lethal concentrations (LC50) and median effect concentrations (EC50) of the pyrethroid insecticide bifenthrin, compare their ability to assess toxicity to the use of whole sediment concentrations, as well as to make comparisons of the concentrations derived using each method in order to make assessments of accuracy and extrapolation potential. Four metrics were compared including SPME fiber concentration, pore water concentration derived using SPMEs, 6 h Tenax extractable concentration, and 24 h Tenax extractable concentration. The variation among the LC50s and EC50s in each sediment derived using bioavailability-based methods was comparable to variation among organic carbon normalized sediment concentrations, but improved over whole sediment concentrations. There was a significant linear relationship between SPME or Tenax and organic carbon normalized sediment concentrations. Additionally, there was a significant relationship between the SPME and Tenax concentrations across sediments. The significant linear relationship between SPME and Tenax concentrations further demonstrates that these bioavailability-based endpoints are interrelated. This study derived bioavailability-based benchmarks that may prove to be more accurate than sediment-based ones in predicting toxicity across sediment types.

  9. Toxicity of four sulfonamide antibiotics to the freshwater amphipod Hyalella azteca.

    Science.gov (United States)

    Bartlett, Adrienne J; Balakrishnan, V K; Toito, J; Brown, L R

    2013-04-01

    Sulfonamides are a widely used class of antibiotics; however, there are few toxicological data available with which to conduct environmental risk assessments for these compounds. Therefore, the toxicity of four sulfonamides (sulfaguanidine, sulfathiazole, sulfamerazine, and sulfasalazine) to Hyalella azteca was assessed in chronic (four-week), water-only exposures. Survival was evaluated weekly, and growth was measured at the end of the test. Four-week lethal concentrations associated with 50% mortality (LC50s) for sulfaguanidine, sulfathiazole, and sulfamerazine were 0.90, 1.6, and 3.9 µM, respectively. Sulfaguanidine caused effects on survival more quickly and at lower concentrations than sulfathiazole or sulfamerazine. These differences were more pronounced at week 1 than week 4, when sulfaguanidine LC50s were 8 to 20 times lower and 2 to 4 times lower, respectively. Growth was affected by sulfathiazole but was a less sensitive end point than survival, with an effective concentration associated with 50% reduction in growth (EC50) of 13 µM, whereas sulfaguanidine and sulfamerazine caused negligible effects on growth. Sulfasalazine had no effect on survival or growth at any concentration tested, up to 13 µM. The effects observed in the present study occurred at concentrations exceeding those typically found in environmental waters. However, given that LC50s decreased with exposure duration (except for sulfasalazine), the present study demonstrates the importance of conducting longer-term tests to adequately assess the environmental toxicity of sulfonamides.

  10. Lac Dufault sediment core trace metal distribution, bioavailability and toxicity to Hyalella azteca

    Energy Technology Data Exchange (ETDEWEB)

    Nowierski, Monica [Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1 (Canada); Dixon, D. George [Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1 (Canada); Borgmann, Uwe [National Water Research Institute, Canada Centre for Inland Waters, 867 Lakeshore Road, PO Box 5050, Burlington, Ontario L7R 4A6 (Canada)]. E-mail: uwe.borgmann@ec.gc.ca

    2006-02-15

    To determine changes in metal distribution, bioavailability and toxicity with sediment depth, two 20-cm-long replicate cores were collected from a lake historically subjected to the influence of metal mining and smelting activity. The vertical distribution of Pb, Cd and Cu in sediment was similar for all three metals, with the surface layers showing enrichment and the deeper (pre-industrial) layers showing lower concentrations. Toxicity of each sediment core section was determined in laboratory tests with the freshwater amphipod Hyalella azteca. Bioavailable metal in each sediment slice was estimated from metal concentrations in overlying water in these toxicity tests and, for Cd, also from metal bioaccumulation. The profile for Cd in tissue was comparable to Cd in sediment and overlying water, but relative Cd bioavailability from sediment increased with sediment depth. Survival increased with increasing sediment depth, suggesting that surface sediments were probably less or non-toxic before industrialization. - Toxicity and bioaccumulation tests with sediment cores provide more information on biological effects of metals than surface sediment tests.

  11. Acute and chronic toxicity of lead in water and diet to the amphipod Hyalella azteca

    Science.gov (United States)

    Besser, J.M.; Brumbaugh, W.G.; Brunson, E.L.; Ingersoll, C.G.

    2005-01-01

    We evaluated the influence of waterborne and dietary lead (Pb) exposure on the acute and chronic toxicity of Pb to the amphipod Hyalella azteca. Test solutions were generated by a modified diluter with an extended (24-h) equilibration period. Acute (96-h) toxicity of Pb varied with water hardness in the range of 71 to 275 mg/L as CaCO3, despite similar dissolved Pb concentrations. Acute toxicity was greatest in soft test water, with less than 50% survival at the lowest dissolved Pb concentration (151 ??g/L). Survival also was significantly reduced in medium-hardness water but not in hard test water. In chronic (42-d) studies, amphipods were exposed to waterborne Pb and fed either a control diet or a diet equilibrated with waterborne Pb levels. For animals fed the control diet, the median lethal concentration (LC50) for Pb was 24 ??g/L (as dissolved Pb), and significant reductions in survival occurred at 16 ??g/L. Exposure to Pb-treated diets significantly increased toxicity across a wide range of dissolved Pb concentrations, with a LC50 of 16 ??g/L and significant reductions in growth and reproduction at 3.5 ??g/L. Significant effects on growth and reproduction occurred at dissolved Pb concentrations close to the current U.S. chronic water-quality criterion. Our results suggest that both aqueous- and dietary-exposure pathways contribute significantly to chronic Pb exposure and toxic effects in aquatic biota. ?? 2005 SETAC.

  12. Fish and land use influence Gammarus lacustris and Hyalella azteca (Amphipoda) densities in large wetlands across the upper Midwest

    Science.gov (United States)

    Anteau, Michael J.; Afton, Alan D.; Anteau, Andrea C.E.; Moser, E. Barry

    2011-01-01

    Gammarus lacustrisK/i> and Ki>Hyalella azteca (hereafter G. lacustris and H. azteca, respectively) are important components of secondary production in wetlands and shallow lakes of the upper Midwest, USA. Within the past 50 years, amphipod densities have decreased while occurrences of fish and intensity of agricultural land use have increased markedly across this landscape. We investigated influences of fish, sedimentation, and submerged aquatic vegetation (SAV) on densities of G. lacustris and H. azteca in semipermanent and permanent wetlands and shallow lakes (n = 283) throughout seven eco-physiographic regions of Iowa, Minnesota, and North Dakota during 2004–2005. G. lacustris and H. azteca densities were positively correlated with densities of SAV (P P P = 0.01 and P = 0.013, respectively) and with high densities of fathead minnows (Pimephales promelas; P P = 0.033, respectively). H. azteca densities also were negatively correlated with densities of small fish (e.g., other minnows [Cyprinidae] and sticklebacks [Gasterosteidae]; P = 0.048) and common carp (Cyprinus spp.; P = 0.022). G. lacustris densities were negatively correlated with high levels of suspended solids (an index for sedimentation; P H. azteca densities were positively correlated with the width of upland-vegetation buffers (P = 0.004). Our results indicate that sedimentation and fish reduce amphipod densities and may contribute to the current low densities of amphipods in the upper Midwest. Thus, removing/excluding fish, and providing a thick buffer of upland vegetation around wetlands may help restore amphipod densities and wetland and water quality within this landscape.

  13. Multiple origins of pyrethroid insecticide resistance across the species complex of a nontarget aquatic crustacean, Hyalella azteca.

    Science.gov (United States)

    Weston, Donald P; Poynton, Helen C; Wellborn, Gary A; Lydy, Michael J; Blalock, Bonnie J; Sepulveda, Maria S; Colbourne, John K

    2013-10-08

    Use of pesticides can have substantial nonlethal impacts on nontarget species, including driving evolutionary change, often with unknown consequences for species, ecosystems, and society. Hyalella azteca, a species complex of North American freshwater amphipods, is widely used for toxicity testing of water and sediment and has frequently shown toxicity due to pyrethroid pesticides. We demonstrate that 10 populations, 3 from laboratory cultures and 7 from California water bodies, differed by at least 550-fold in sensitivity to pyrethroids. The populations sorted into four phylogenetic groups consistent with species-level divergence. By sequencing the primary pyrethroid target site, the voltage-gated sodium channel, we show that point mutations and their spread in natural populations were responsible for differences in pyrethroid sensitivity. At least one population had both mutant and WT alleles, suggesting ongoing evolution of resistance. Although nonresistant H. azteca were susceptible to the typical neurotoxic effects of pyrethroids, gene expression analysis suggests the mode of action in resistant H. azteca was not neurotoxicity but was oxidative stress sustained only at considerably higher pyrethroid concentrations. The finding that a nontarget aquatic species has acquired resistance to pesticides used only on terrestrial pests is troubling evidence of the impact of chronic pesticide transport from land-based applications into aquatic systems. Our findings have far-reaching implications for continued uncritical use of H. azteca as a principal species for monitoring and environmental policy decisions.

  14. Oxidative stress induced in Hyalella azteca by an effluent from a NSAID-manufacturing plant in Mexico.

    Science.gov (United States)

    Novoa-Luna, Karen Adriana; Romero-Romero, Rubí; Natividad-Rangel, Reyna; Galar-Martínez, Marcela; SanJuan-Reyes, Nely; García-Medina, Sandra; Martínez-Vieyra, Catalina; Neri-Cruz, Nadia; Gómez-Oliván, Leobardo Manuel

    2016-09-01

    Production in the pharmaceutical industry has increased and along with it, the amount of wastewater of various characteristics and contaminant concentrations. The main chemicals in these effluents are solvents, detergents, disinfectants-such as sodium hypochlorite (NaClO)-and pharmaceutical products, all of which are potentially ecotoxic. Therefore, this study aimed to evaluate the oxidative stress induced in the amphipod Hyalella azteca by the effluent from a nonsteroidal anti-inflammatory drug (NSAID)-manufacturing plant. The median lethal concentration (72 h-LC50) was determined and H. azteca were exposed to the lowest observed adverse effect level (0.0732 %) for 12, 24, 48 and 72 h, and biomarkers of oxidative stress were evaluated [hydroperoxide content (HPC), lipid peroxidation (LPX), protein carbonyl content (PCC), and the activity of the superoxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)]. Statistically significant increases with respect to the control group (P azteca at all exposure times. Antioxidant enzymes activity SOD, CAT and GPx activity also increased significantly (P azteca.

  15. Toxicity of sediment-associated pesticides to Chironomus dilutus and Hyalella azteca.

    Science.gov (United States)

    Ding, Yuping; Weston, Donald P; You, Jing; Rothert, Amanda K; Lydy, Michael J

    2011-07-01

    Two hundred sediment samples were collected and their toxicity evaluated to aquatic species in a previous study in the agriculturally dominated Central Valley of California, United States. Pyrethroid insecticides were the main contributors to the observed toxicity. However, mortality in approximately one third of the toxic samples could not be explained solely by the presence of pyrethroids in the matrices. Hundreds of pesticides are currently used in the Central Valley of California, but only a few dozen are analyzed in standard environmental monitoring. A significant amount of unexplained sediment toxicity may be due to pesticides that are in widespread use that but have not been routinely monitored in the environment, and even if some of them were, the concentrations harmful to aquatic organisms are unknown. In this study, toxicity thresholds for nine sediment-associated pesticides including abamectin, diazinon, dicofol, fenpropathrin, indoxacarb, methyl parathion, oxyfluorfen, propargite, and pyraclostrobin were established for two aquatic species, the midge Chironomus dilutus and the amphipod Hyalella azteca. For midges, the median lethal concentration (LC₅₀) of the pesticides ranged from 0.18 to 964 μg/g organic carbon (OC), with abamectin being the most toxic and propargite being the least toxic pesticide. A sublethal growth endpoint using average individual ash-free dry mass was also measured for the midges. The no-observable effect concentration values for growth ranged from 0.10 to 633 μg/g OC for the nine pesticides. For the amphipods, fenpropathrin was the most toxic, with an LC₅₀ of 1-2 μg/g OC. Abamectin, diazinon, and methyl parathion were all moderately toxic (LC₅₀s 2.8-26 μg/g OC). Dicofol, indoxacarb, oxyfluorfen, propargite, and pyraclostrobin were all relatively nontoxic, with LC₅₀s greater than the highest concentrations tested. The toxicity information collected in the present study will be helpful in decreasing the

  16. Survival, growth, and body residues of Hyalella azteca (Saussure) exposed to fipronil contaminated sediments from non-vegetated and vegetated microcosms

    Science.gov (United States)

    We assessed chronic effects of fipronil and metabolite contaminated sediments from non-vegetated and Thallia dealbata vegetated wetland microcosms on Hyalella azteca during wet and dry exposures. Mean sediment concentrations (ng g-1) ranged from 0.72-1.26, 0.01-0.69, 0.07-0.23, and 0.49-7.87 for fip...

  17. Chronic TiO2 nanoparticle exposure to a benthic organism, Hyalella azteca: Impact of solar UV radiation and material surface coatings on toxicity

    Science.gov (United States)

    The present study examined the chronic toxicity of TiO2 nanoparticles (nano-TiO2) to a representative benthic species, Hyalella azteca, using an industry standard, P25, and a coated nano-TiO2 used in commercial products. There is limited information on the chronic effects of nano...

  18. Chronic TiO2 nanoparticle exposure to a benthic organism, Hyalella azteca: Impact of solar UV radiation and material surface coatings on toxicity

    Science.gov (United States)

    The present study examined the chronic toxicity of TiO2 nanoparticles (nano-TiO2) to a representative benthic species, Hyalella azteca, using an industry standard, P25, and a coated nano-TiO2 used in commercial products. There is limited information on the chronic effects of nano...

  19. Chronic toxicity of arsenic, cobalt, chromium and manganese to Hyalella azteca in relation to exposure and bioaccumulation

    Energy Technology Data Exchange (ETDEWEB)

    Norwood, W.P. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada) and Aquatic Ecosystems Protection Research Division, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada)]. E-mail: warren.norwood@ec.gc.ca; Borgmann, U. [Aquatic Ecosystems Protection Research Division, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada); Dixon, D.G. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada)

    2007-05-15

    Chronic toxicity of As, Co, Cr and Mn to Hyalella azteca can be described using a saturation-based mortality model relative to total-body or water metal concentration. LBC25s (total-body metal concentrations resulting in 25% mortality in 4 weeks) were 125, 103, 152 and 57,900 nmol g{sup -1} dry weight for As, Co, Cr and Mn respectively. LC50s (metal concentrations in water resulting in 25% mortality in 4 weeks) were 5600, 183, 731, and 197,000 nmol L{sup -1}, respectively. A hormesis growth response to As exposure was observed. Growth was a more variable endpoint than mortality for all four toxicants; however, confidence limits based on growth and mortality all overlapped, except Cr which had no effect on growth. Mn toxicity was greater in glass test containers compared to plastic. Bioaccumulation of As, Co, Cr, and Mn was strongly correlated with, and is useful for predicting, chronic mortality. - Chronic toxicity of As, Co, Cr and Mn to Hyalella azteca can be described using a saturation-based mortality model in relationship to total-body or water metal concentration.

  20. Bioaccumulation of the synthetic hormone 17alpha-ethinylestradiol in the benthic invertebrates Chironomus tentans and Hyalella azteca.

    Science.gov (United States)

    Dussault, Eve B; Balakrishnan, Vimal K; Borgmann, Uwe; Solomon, Keith R; Sibley, Paul K

    2009-09-01

    The present study investigated the bioaccumulation of the synthetic hormone 17alpha-ethinylestradiol (EE2) in the benthic invertebrates Chironomus tentans and Hyalella azteca, in water-only and spiked sediment assays. Water and sediment residue analysis was performed by LC/MS-MS, while biota extracts were analyzed using both LC/MS-MS and a recombinant yeast estrogen receptor assay. At the lowest exposure concentration, C. tentans accumulated less EE2 than H. azteca in the water-only assays (p=0.0004), but due to different slopes, this difference subsided with increasing concentrations; at the exposure concentration of 1mg/L, C. tentans had a greater body burden than H. azteca (p=0.02). In spiked sediments, C. tentans had the greatest EE2 accumulation (1.2+/-0.14 vs. 0.5+/-0.05 microg/gdw, n=4). Measurements in H. azteca indicated a negligible contribution from the sediments to the uptake of EE2 in this species. These differences were likely due to differences in the behavior and life history of the two species (epibenthic vs. endobenthic). Water-only bioaccumulation factors (BAFs) calculated at the lowest exposure concentration were significantly smaller in C. tentans than in H. azteca (31 vs. 142, respectively; pazteca (0.8 vs. 0.3; p<0.0001). Extracts of the exposed animals caused a response in a recombinant yeast estrogen receptor assay, thus confirming the estrogenic activity of the samples, presumably from EE2 and its estrogenic metabolites. The results of the present study suggest that consumption of invertebrate food items could provide an additional source of exposure to estrogenic substances in vertebrate predators.

  1. Greatly reduced bioavailability and toxicity of polycyclic aromatic hydrocarbons to Hyalella azteca in sediments from manufactured-gas plant sites.

    Science.gov (United States)

    Kreitinger, Joseph P; Neuhauser, Edward F; Doherty, Francis G; Hawthorne, Steven B

    2007-06-01

    The toxicity of polycyclic aromatic hydrocarbons (PAHs) to Hyalella azteca, was measured in 34 sediment samples collected from four manufactured-gas plant (MGP) sites ranging in total PAH16 (sum of 16 U.S. Environmental Protection Agency priority pollutant PAHs) concentrations from 4 to 5700 mg/kg, total organic carbon content from 0.6 to 11%, and soot carbon from 0.2 to 5.1%. The survival and growth of H. azteca in 28-d bioassays were unrelated to total PAH concentration, with 100% survival in one sediment having 1,730 mg/kg total PAH16, whereas no survival was observed in sediment samples with concentrations as low as 54 mg/kg total PAH16. Twenty-five of the 34 sediment samples exceeded the probable effects concentration screening value of 22.8 mg/kg total PAH13 (sum of 13 PAHs) and equilibrium partitioning sediment benchmarks for PAH mixtures (on the basis of the measurement of 18 parent PAHs and 16 groups of alkylated PAHs, [PAH34]); yet, 19 (76%) of the 25 samples predicted to be toxic were not toxic to H. azteca. However, the toxicity of PAHs to H. azteca was accurately predicted when either the rapidly released concentrations as determined by mild supercritical fluid extraction (SFE) or the pore-water concentrations were used to establish the bioavailability of PAHs. These results demonstrate that the PAHs present in many sediments collected from MGP sites have low bioavailability and that both the measurement of the rapidly released PAH concentrations with mild SFE and the dissolved pore-water concentrations of PAHs are useful tools for estimating chronic toxicity to H. azteca.

  2. The evaluation of 3 diets for rearing Hyalella azteca and the influence of diet on acute ammonia toxicity.

    Science.gov (United States)

    Kennedy, Lisa M; Watson-Leung, Trudy L; Poirier, David G

    2016-10-01

    Three Hyalella azteca cultures were reared on different diets since birth, reflecting the recommended diets of various investigators. The 3 diets consisted of fish flakes (FF), a mixture of fish flakes supplemented with the diatom Thalassiosira weissflogii (FF-D), and a mixture of fish flakes supplemented with yeast, cereal grass media, and trout chow (FF-YCT). The 3 diets were evaluated by comparing 20 wk of culturing data, along with the organism's response to standard 96-h toxicity testing with ammonium chloride over a range of pH and temperature. Hyalella azteca fed the FF-D diet had the highest overall survival rate (96.6%, standard deviation [SD] 4.3%) compared to those fed the FF diet (92.0%, SD 12.7%), or the FF-YCT diet (91.1%, SD 14.8%), although difference in survival was not statistically significant. Organisms fed the FF-D diet produced a higher number of young per week per adult (6.1, SD 2.8) than the FF diet (5.1, SD 2.2), or the FF-YCT diet (4.0, SD 1.2), although differences were not statistically significant. Of the diets evaluated, H. azteca reared on the FF-D diet were often significantly more resistant to total and un-ionized ammonia toxicity in acute 96-h testing than those reared on the other 2 diets across the 2 temperatures and 5 pHs tested, suggesting this may be the most optimal diet for this species. Environ Toxicol Chem 2016;35:2416-2424. © 2016 SETAC.

  3. Oxidized Carbo-Iron causes reduced reproduction and lower tolerance of juveniles in the amphipod Hyalella azteca.

    Science.gov (United States)

    Weil, Mirco; Meißner, Tobias; Springer, Armin; Bundschuh, Mirco; Hübler, Lydia; Schulz, Ralf; Duis, Karen

    2016-12-01

    For in situ remediation of groundwater contaminated by halogenated hydrocarbons Carbo-Iron(®), a composite of microscale activated carbon and nano Fe(0), was developed. Against the background of intended release of Carbo-Iron into the environment in concentrations in the g/L-range, potential ecotoxicological consequences were evaluated in the present study. The nano Fei(0) in Carbo-Iron acts as reducing agent and is oxidized in aqueous systems by chlorinated solvents, groundwater constituents (e.g. dissolved oxygen) and anaerobic corrosion. As Carbo-Iron is generally oxidized rapidly after application into the environment, the oxidized state is environmentally most relevant, and Carbo-Iron was used in its oxidized form in the ecotoxicological tests. The amphipod Hyalella azteca was selected as a surrogate test species for functionally important groundwater crustaceans. Effects of Carbo-Iron on H. azteca were determined in a 10-d acute test, a 7-d feeding activity test and a 42-d chronic test. Additionally, a 56-d life cycle test was performed with a modified design to further evaluate effects of Carbo-Iron on adult H. azteca and their offspring. The size of Carbo-Iron particles in stock and test suspensions was determined via dynamic light scattering. Potential uptake of particles into test organisms was investigated using transmission and scanning electron microscopy. At the termination of the feeding and acute toxicity test (i.e. after 7 and 10 d of exposure, respectively), Carbo-Iron had a significant effect on the weight, length and feeding rate of H. azteca at the highest test concentration of 100mg/L. While an uptake of Carbo-Iron into the gut was observed, no passage into the surrounding tissue was detected. In both chronic tests, the number of offspring was the most sensitive endpoint and significant effects were recorded at concentrations ≥50mg/L (42-d experiment) and ≥12.5mg/L (56-d experiment). Parental exposure to oxidized Carbo-Iron significantly

  4. Contaminants in stream sediments from seven United States metropolitan areas: part II--sediment toxicity to the amphipod Hyalella azteca and the midge Chironomus dilutus.

    Science.gov (United States)

    Kemble, Nile E; Hardesty, Douglas K; Ingersoll, Christopher G; Kunz, James L; Sibley, Paul K; Calhoun, Daniel L; Gilliom, Robert J; Kuivila, Kathryn M; Nowell, Lisa H; Moran, Patrick W

    2013-01-01

    Relationships between sediment toxicity and sediment chemistry were evaluated for 98 samples collected from seven metropolitan study areas across the United States. Sediment-toxicity tests were conducted with the amphipod Hyalella azteca (28 day exposures) and with the midge Chironomus dilutus (10 day exposures). Overall, 33 % of the samples were toxic to amphipods and 12 % of the samples were toxic to midge based on comparisons with reference conditions within each study area. Significant correlations were observed between toxicity end points and sediment concentrations of trace elements, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), or organochlorine (OC) pesticides; however, these correlations were typically weak, and contaminant concentrations were usually below sediment-toxicity thresholds. Concentrations of the pyrethroid bifenthrin exceeded an estimated threshold of 0.49 ng/g (at 1 % total organic carbon) in 14 % of the samples. Of the samples that exceeded this bifenthrin toxicity threshold, 79 % were toxic to amphipods compared with 25 % toxicity for the samples below this threshold. Application of mean probable effect concentration quotients (PECQs) based on measures of groups of contaminants (trace elements, total PAHs, total PCBs, OC pesticides, and pyrethroid pesticides [bifenthrin in particular]) improved the correct classification of samples as toxic or not toxic to amphipods compared with measures of individual groups of contaminants.

  5. Examining impacts of current-use pesticides in Southern Ontario using in situ exposures of the amphipod Hyalella azteca.

    Science.gov (United States)

    Bartlett, Adrienne J; Struger, John; Grapentine, Lee C; Palace, Vince P

    2016-05-01

    In situ exposures with Hyalella azteca were used to assess impacts of current-use pesticides in Southern Ontario, Canada. Exposures were conducted over 2 growing seasons within areas of high pesticide use: 1 site on Prudhomme Creek and 3 sites on Twenty Mile Creek. Three sites on Spencer Creek, an area of low pesticide use, were added in the second season. Surface water samples were collected every 2 wk to 3 wk and analyzed for a suite of pesticides. Hyalella were exposed in situ for 1 wk every 4 wk to 6 wk, and survival and acetylcholinesterase (AChE) activity were measured. Pesticides in surface waters reflected seasonal use patterns: lower concentrations in spring and fall and higher concentrations during summer months. Organophosphate insecticides (chlorpyrifos, azinphos methyl, diazinon) and acid herbicides (2,4-dichlorophenoxyacetic acid [2,4-D], mecoprop) were routinely detected in Prudhomme Creek, whereas neutral herbicides (atrazine, metolachlor) dominated the pesticide signature of Twenty Mile Creek. Spencer Creek contained fewer pesticides, which were measured at lower concentrations. In situ effects also followed seasonal patterns: higher survival and AChE activity in spring and fall, and lower survival and AChE activity during summer months. The highest toxicity was observed at Prudhomme Creek and was primarily associated with organophosphates. The present study demonstrated that current-use pesticides in Southern Ontario were linked to in situ effects and identified sites of concern requiring further investigation.

  6. Genotype and toxicity relationships among Hyalella azteca: I. Acute exposure to metals or low pH

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Y.; Guttman, S.I.; Oris, J.T.; Bailer, A.J.

    2000-05-01

    Comparative genotype and toxin interactions at three polymorphic enzyme loci were examined in a laboratory population of amphipods (Hyalella azteca) during acute exposure to cadmium, zinc, copper, lead, or low pH. Significant toxin-genotype interactions were observed using logistic regression to model mortality in ten of 15 analyses. Both stressor-specific and nonspecific modes of selection were observed. In general, low pH selected for different genotypes than those selected by metals, especially zinc. Different modes of selection were also observed when amphipods were exposed to different metals. These results suggest that exposure to low pH would significantly reduce the ability of H. azteca to survive subsequent contamination by metals; exposure to stressors in the reverse order would also compromise a population's chance of survival. A genetic distance analysis showed that the magnitude of genetic differentiation consistently increased among survivors compared with that of the initial populations. These increases in genetic divergence estimates suggest that acute exposure to metals or low pH may have an evolutionarily significant impact on the species. They also suggest that both genotype frequency and genetic distance measures (based on allozyme data) may be used as bioindicators for environmental monitoring programs. Validation of such bioindicators requires an understanding of the population's genetic background, genetic structure, and history.

  7. Screening differentially expressed genes in an amphipod (Hyalella azteca) exposed to fungicide vinclozolin by suppression subtractive hybridization.

    Science.gov (United States)

    Wu, Yun H; Wu, Tsung M; Hong, Chwan Y; Wang, Yei S; Yen, Jui H

    2014-01-01

    Vinclozolin, a dicarboximide fungicide, is an endocrine disrupting chemical that competes with an androgenic endocrine disruptor compound. Most research has focused on the epigenetic effect of vinclozolin in humans. In terms of ecotoxicology, understanding the effect of vinclozolin on non-target organisms is important. The expression profile of a comprehensive set of genes in the amphipod Hyalella azteca exposed to vinclozolin was examined. The expressed sequence tags in low-dose vinclozolin-treated and -untreated amphipods were isolated and identified by suppression subtractive hybridization. DNA dot blotting was used to confirm the results and establish a subtracted cDNA library for comparing all differentially expressed sequences with and without vinclozolin treatment. In total, 494 differentially expressed genes, including hemocyanin, heatshock protein, cytochrome, cytochrome oxidase and NADH dehydrogenase were detected. Hemocyanin was the most abundant gene. DNA dot blotting revealed 55 genes with significant differential expression. These genes included larval serum protein 1 alpha, E3 ubiquitin-protein ligase, mitochondrial cytochrome c oxidase, mitochondrial protein, proteasome inhibitor, hemocyanin, zinc-finger-containing protein, mitochondrial NADH-ubiquinone oxidoreductase and epididymal sperm-binding protein. Vinclozolin appears to upregulate stress-related genes and hemocyanin, related to immunity. Moreover, vinclozolin downregulated NADH dehydrogenase, related to respiration. Thus, even a non-lethal concentration of vinclozolin still has an effect at the genetic level in H. azteca and presents a potential risk, especially as it would affect non-target organism hormone metabolism.

  8. TRACKING PYRETHROID TOXICITY IN SURFACE WATER SAMPLES: EXPOSURE DYNAMICS AND TOXICITY IDENTIFICATION TOOLS FOR LABORATORY TESTS WITH HYALELLA AZTECA (AMPHIPODA).

    Science.gov (United States)

    Deanovic, Linda A; Stillway, Marie; Hammock, Bruce G; Fong, Stephanie; Werner, Inge

    2017-09-09

    Pyrethroid insecticides are commonly used in pest control and are present at toxic concentrations in surface waters of agricultural and urban areas worldwide. Monitoring is challenging due to their high hydrophobicity and low toxicity thresholds, which often fall below the detection limits of analytical methods. Standard daphnid bioassays used in surface water monitoring are not sensitive enough to protect more susceptible invertebrate species such as the amphipod, Hyalella azteca, and chemical loss during toxicity testing is of concern. In this study, we quantified toxicity loss during storage and testing, using both natural and synthetic water, and present a tool to enhance toxic signal strength for improved sensitivity of H. azteca toxicity tests. The average half-life during storage in LDPE cubitainers at 4°C of five pyrethroids (permethrin, bifenthrin, lambda-cyhalothrin, cyfluthrin, esfenvalerate) and one organophosphate (chlorpyrifos; used as reference) was 1.4 d, and piperonyl butoxide (PBO) proved an effective tool to potentiate toxicity. We conclude that toxicity tests on ambient water samples containing these hydrophobic insecticides are likely to underestimate toxicity present in the field, and mimic short pulse rather than continuous exposures. Where these chemicals are of concern, the addition of PBO during testing can yield valuable information on their presence or absence. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  9. Pairing behavior and reproduction in Hyalella azteca as sensitive endpoints for detecting long-term consequences of pesticide pulses.

    Science.gov (United States)

    Pedersen, Signe; Palmqvist, Annemette; Thorbek, Pernille; Hamer, Mick; Forbes, Valery

    2013-11-15

    The aim of the present study was to examine acute and delayed effects of pulse exposure of the pyrethroid pesticide, permethrin, on precopulatory pairs of Hyalella azteca. Pairs of H. azteca were exposed to a single 1h pulse of different nominal concentrations of permethrin: 0, 0.3, 0.9 or 2.7 μg/L. During exposure, pairing behavior was observed, and during a 56 day post-exposure period the treatments were monitored for pairing behavior, survival and reproductive output. All permethrin-exposed pairs separated within minutes during exposure and shortly thereafter became immobile; however they regained mobility after transfer to clean water. The time to re-form pairs was significantly longer in all tested concentrations compared to the control, although all surviving pairs re-formed within the 56 day test period. Nevertheless not all pairs exposed to 0.9 and 2.7 μg/L reproduced. Furthermore the numbers of juveniles produced by pairs exposed to 0.9 and 2.7 μg/L, but not 0.3 μg/L, were lower throughout the entire post-exposure period compared to the control groups, and the total numbers of juveniles produced during 56 days were significantly lower in organisms exposed to 0.9 and 2.7 μg/L, but not 0.3 μg/L, compared to the control groups. The long-term effects of short-term exposure on reproductive behavior of pairs could potentially have consequences for the population dynamics of H. azteca. However, since individual-level responses can both overestimate and underestimate effects at the population level, appropriate population models are needed to reduce the uncertainty in extrapolating between these levels of biological organization.

  10. Responses of Hyalella azteca and phytoplankton to a simulated agricultural runoff event in a managed backwater wetland.

    Science.gov (United States)

    Lizotte, Richard E; Shields, F Douglas; Murdock, Justin N; Knight, Scott S

    2012-05-01

    We assessed the aqueous toxicity mitigation capacity of a hydrologically managed floodplain wetland following a synthetic runoff event amended with a mixture of sediments, nutrients (nitrogen and phosphorus), and pesticides (atrazine, S-metolachlor, and permethrin) using 48-h Hyalella azteca survival and phytoplankton pigment, chlorophyll a. The runoff event simulated a 1h, 1.27 cm rainfall event from a 16 ha agricultural field. Water (1L) was collected every 30 min within the first 4h, every 4h until 48 h, and on days 5, 7, 14, 21, and 28 post-amendment at distances of 0, 10, 40, 300 and 500 m from the amendment point for chlorophyll a, suspended sediment, nutrient, and pesticide analyses. H. azteca 48-h laboratory survival was assessed in water collected at each site at 0, 4, 24, 48 h, 5 d and 7 d. Greatest sediment, nutrient, and pesticide concentrations occurred within 3h of amendment at 0m, 10 m, 40 m, and 300 m downstream. Sediments and nutrients showed little variation at 500 m whereas pesticides peaked within 48 h but at azteca survival significantly decreased within 48 h of amendment up to 300 m in association with permethrin concentrations. Chlorophyll a decreased within the first 24h of amendment up to 40m primarily in conjunction with herbicide concentrations. Variations in chlorophyll a at 300 and 500 m were associated with nutrients. Managed floodplain wetlands can rapidly and effectively trap and process agricultural runoff during moderate rainfall events, mitigating impacts to aquatic invertebrates and algae in receiving aquatic systems.

  11. Inter-laboratory validation of organism recovery for use in 42 day sediment toxicity tests with Hyalella azteca.

    Science.gov (United States)

    Taylor, Lisa N; Novak, Lesley

    2016-10-03

    Environment and Climate Change Canada (ECCC) has developed a 42 day sediment toxicity test that includes a reproduction endpoint with the freshwater amphipod Hyalella azteca. The new methodology conducts the entire exposure in sediment; in contrast to existing standardized methods where adults are transferred to a water-only exposure before release of their first brood at Day 28. This mid-test transfer to clean water was due to the results of a juvenile H. azteca recovery trial conducted in the 1990s which concluded that reproductive endpoints could be biased because of low recovery of young amphipods from sediment. Using a new procedure and reduced volume of sediment, an inter-laboratory recovery trial was conducted using 2 to 5 day old H. azteca added to control sediment. A total of 29 technicians from eight laboratories participated in the present study. The average recovery for all laboratories and all technicians was 76% (Coefficient of Variation (CV) = 30%). Based on an initial target recovery of at least 80%, 19 out of 29 (66%) of technicians met this criterion, with an average recovery for this group of 88% (CV = 8.3%). Factors that reduced recovery success included: not using a light table, technicians with minimal sediment testing experience and the use of imported young amphipods with limited acclimation. Excluding those results, the overall average recovery which included 17 participating technicians, increased from 76 to 88% and lowered the CV from 30 to 8.6%. Based on these results, ECCC will recommend ≥85% average recovery of young in control sediment and require ≥80% as a technician performance criterion in its new test design for the reproduction methodology. This article is protected by copyright. All rights reserved.

  12. Validation of a chronic dietary cadmium bioaccumulation and toxicity model for Hyalella azteca exposed to field-contaminated periphyton and lake water.

    Science.gov (United States)

    Golding, Lisa A; Borgmann, Uwe; Dixon, D George

    2011-11-01

    A model previously developed in the laboratory to predict chronic bioaccumulation and toxicity of cadmium to Hyalella azteca from a diet of periphyton was validated by comparing predictions with measurements of Cd in two exposure scenarios: laboratory-cultured H. azteca exposed for 28 d to field-contaminated water and periphyton, and Cd measured in field-collected H. azteca. In both exposure scenarios, model predictions of bioaccumulation were shown to be robust; however, effects on Cd bioaccumulation from complexation with dissolved organic carbon (DOC) and inhibition of Cd bioaccumulation by Ca²⁺ must be incorporated into the model to permit its wider application. The model predicted that 80 to 84% of Cd in H. azteca came from periphyton when H. azteca were chronically exposed to dissolved Cd in lake water at 2.63 to 3.01 nmol/L and periphyton at 1,880 to 2,630 nmol/g ash-free dry mass. Dietary Cd contributed markedly to the model-predicted decrease in 28-d survival to 74% at environmental Cd concentrations in food and water. In reality, survival decreased to 10%. The lower than predicted survival likely was due to the higher nutritional quality of periphyton used to develop the model in the laboratory compared with the field-collected periphyton. Overall, this research demonstrated that Cd in a periphyton diet at environmental concentrations can contribute to chronic toxicity in H. azteca.

  13. Cadmium bioavailability to Hyalella azteca from a periphyton diet compared to an artificial diet and application of a biokinetic model

    Energy Technology Data Exchange (ETDEWEB)

    Golding, Lisa A., E-mail: lisa.golding@csiro.au [Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Borgmann, Uwe [Environment Canada, 867 Lakeshore Road, Burlington, Ontario L7R 4A6 (Canada); George Dixon, D. [Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2013-01-15

    Differences between the bioavailability of cadmium in a periphyton diet and an artificial laboratory diet (TetraMin{sup Registered-Sign }) have important consequences for predicting bioaccumulation and toxicity in the freshwater amphipod Hyalella azteca. The assimilation efficiency (AE) of Cd was compared between periphyton and TetraMin{sup Registered-Sign} at low (1510 and 358 nmol/g ash-free dry mass respectively) and chronically lethal (31,200 and 2890 nmol/g ash-free dry mass respectively) Cd concentrations and in fresh and dry forms using a {sup 109}Cd radiotracer pulse-chase feeding technique. Assimilation efficiency of Cd from periphyton (AE = 3-14%) was lower than that for TetraMin{sup Registered-Sign} (AE = 44-86%) regardless of Cd concentration or food form. Ingestion rate (IR) was lower for dry than fresh forms of periphyton (0.042 and 0.16 g AFDM/g H. azteca/day respectively) and TetraMin{sup Registered-Sign} (0.19 and 0.87 AFDM/g H. azteca/day respectively) and depuration rate (k{sub e}) did not differ statistically with food type, form or Cd concentration (0.032-0.094 d{sup -1}). Biokinetic models with parameters of AE, IR and k{sub e} were used to estimate bioaccumulation from the separate food types. These estimates were compared to those from an independent chronic Cd saturation bioaccumulation model. While the model estimates did not concur, a sensitivity analysis indicated that AE and IR were the most influential biokinetic model parameters for Cd in periphyton and TetraMin{sup Registered-Sign} respectively. It was hypothesized that AE was underestimated for Cd in periphyton due to a non-adapted gut enzyme system and IR was overestimated for Cd in TetraMin{sup Registered-Sign} due to an initial rapid ingestion phase in H. azteca's feeding habits. This research demonstrated the importance of using ecologically relevant food types in laboratory experiments and verifying acute biokinetic model predictions of dietary metal contribution with

  14. Cadmium bioavailability to Hyalella azteca from a periphyton diet compared to an artificial diet and application of a biokinetic model.

    Science.gov (United States)

    Golding, Lisa A; Borgmann, Uwe; George Dixon, D

    2013-01-15

    Differences between the bioavailability of cadmium in a periphyton diet and an artificial laboratory diet (TetraMin(®)) have important consequences for predicting bioaccumulation and toxicity in the freshwater amphipod Hyalella azteca. The assimilation efficiency (AE) of Cd was compared between periphyton and TetraMin(®) at low (1510 and 358 nmol/g ash-free dry mass respectively) and chronically lethal (31,200 and 2890 nmol/g ash-free dry mass respectively) Cd concentrations and in fresh and dry forms using a (109)Cd radiotracer pulse-chase feeding technique. Assimilation efficiency of Cd from periphyton (AE=3-14%) was lower than that for TetraMin(®) (AE=44-86%) regardless of Cd concentration or food form. Ingestion rate (IR) was lower for dry than fresh forms of periphyton (0.042 and 0.16 g AFDM/g H. azteca/day respectively) and TetraMin(®) (0.19 and 0.87 AFDM/g H. azteca/day respectively) and depuration rate (k(e)) did not differ statistically with food type, form or Cd concentration (0.032-0.094 d(-1)). Biokinetic models with parameters of AE, IR and k(e) were used to estimate bioaccumulation from the separate food types. These estimates were compared to those from an independent chronic Cd saturation bioaccumulation model. While the model estimates did not concur, a sensitivity analysis indicated that AE and IR were the most influential biokinetic model parameters for Cd in periphyton and TetraMin(®) respectively. It was hypothesized that AE was underestimated for Cd in periphyton due to a non-adapted gut enzyme system and IR was overestimated for Cd in TetraMin(®) due to an initial rapid ingestion phase in H. azteca's feeding habits. This research demonstrated the importance of using ecologically relevant food types in laboratory experiments and verifying acute biokinetic model predictions of dietary metal contribution with those derived from a chronic exposure which is more representative of a field exposure scenario.

  15. Do pyrethroid-resistant Hyalella azteca have greater bioaccumulation potential compared to non-resistant populations? Implications for bioaccumulation in fish.

    Science.gov (United States)

    Muggelberg, Leslie L; Huff Hartz, Kara E; Nutile, Samuel A; Harwood, Amanda D; Heim, Jennifer R; Derby, Andrew P; Weston, Donald P; Lydy, Michael J

    2017-01-01

    The recent discovery of pyrethroid-resistant Hyalella azteca populations in California, USA suggests there has been significant exposure of aquatic organisms to these terrestrially-applied insecticides. Since resistant organisms are able to survive in relatively contaminated habitats they may experience greater pyrethroid bioaccumulation, subsequently increasing the risk of those compounds transferring to predators. These issues were evaluated in the current study following toxicity tests in water with permethrin which showed the 96-h LC50 of resistant H. azteca (1670 ng L(-1)) was 53 times higher than that of non-resistant H. azteca (31.2 ng L(-1)). Bioaccumulation was compared between resistant and non-resistant H. azteca by exposing both populations to permethrin in water and then measuring the tissue concentrations attained. Our results indicate that resistant and non-resistant H. azteca have similar potential to bioaccumulate pyrethroids at the same exposure concentration. However, significantly greater bioaccumulation occurs in resistant H. azteca at exposure concentrations non-resistant organisms cannot survive. To assess the risk of pyrethroid trophic transfer, permethrin-dosed resistant H. azteca were fed to fathead minnows (Pimephales promelas) for four days, after which bioaccumulation of permethrin and its biotransformation products in fish tissues were measured. There were detectable concentrations of permethrin in fish tissues after they consumed dosed resistant H. azteca. These results show that bioaccumulation potential is greater in organisms with pyrethroid resistance and this increases the risk of trophic transfer when consumed by a predator. The implications of this study extend to individual fitness, populations and food webs.

  16. Calculation and evaluation of sediment effect concentrations for the amphipod Hyalella azteca and the midge Chironomus riparius

    Science.gov (United States)

    Ingersoll, Christopher G.; Haverland, Pamela S.; Brunson, Eric L.; Canfield, Timothy J.; Dwyer, F. James; Henke, Chris; Kemble, Nile E.; Mount, David R.; Fox, Richard G.

    1996-01-01

    Procedures are described for calculating and evaluating sediment effect concentrations (SECs) using laboratory data on the toxicity of contaminants associated with field-collected sediment to the amphipod Hyalella azteca and the midge Chironomus riparius. SECs are defined as the concentrations of individual contaminants in sediment below which toxicity is rarely observed and above which toxicity is frequently observed. The objective of the present study was to develop SECs to classify toxicity data for Great Lake sediment samples tested with Hyalella azteca and Chironomus riparius. This SEC database included samples from additional sites across the United States in order to make the database as robust as possible. Three types of SECs were calculated from these data: (1) Effect Range Low (ERL) and Effect Range Median (ERM), (2) Threshold Effect Level (TEL) and Probable Effect Level (PEL), and (3) No Effect Concentration (NEC). We were able to calculate SECs primarily for total metals, simultaneously extracted metals, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). The ranges of concentrations in sediment were too narrow in our database to adequately evaluate SECs for butyltins, methyl mercury, polychlorinated dioxins and furans, or chlorinated pesticides. About 60 to 80% of the sediment samples in the database are correctly classified as toxic or not toxic depending on type of SEC evaluated. ERMs and ERLs are generally as reliable as paired PELs and TELs at classifying both toxic and non-toxic samples in our database. Reliability of the SECs in terms of correctly classifying sediment samples is similar between ERMs and NECs; however, ERMs minimize Type I error (false positives) relative to ERLs and minimize Type II error (false negatives) relative to NECs. Correct classification of samples can be improved by using only the most reliable individual SECs for chemicals (i.e., those with a higher percentage of correct classification). SECs

  17. An evaluation of the ability of chemical measurements to predict polycyclic aromatic hydrocarbon-contaminated sediment toxicity to Hyalella azteca.

    Science.gov (United States)

    McDonough, Kathleen M; Azzolina, Nicholas A; Hawthorne, Steven B; Nakles, David V; Neuhauser, Edward F

    2010-07-01

    The present study examined the ability of three chemical estimation methods to predict toxicity and nontoxicity of polycyclic aromatic hydrocarbon (PAH) -contaminated sediment to the freshwater benthic amphipod Hyalella azteca for 192 sediment samples from 12 field sites. The first method used bulk sediment concentrations of 34 PAH compounds (PAH34), and fraction of total organic carbon, coupled with equilibrium partitioning theory to predict pore-water concentrations (KOC method). The second method used bulk sediment PAH34 concentrations and the fraction of anthropogenic (black carbon) and natural organic carbon coupled with literature-based black carbon-water and organic carbon-water partition coefficients to estimate pore-water concentrations (KOCKBC method). The final method directly measured pore-water concentrations (pore-water method). The U.S. Environmental Protection Agency's hydrocarbon narcosis model was used to predict sediment toxicity for all three methods using the modeled or measured pore-water concentration as input. The KOC method was unable to predict nontoxicity (83% of nontoxic samples were predicted to be toxic). The KOCKBC method was not able to predict toxicity (57% of toxic samples were predicted to be nontoxic) and, therefore, was not protective of the environment. The pore-water method was able to predict toxicity (correctly predicted 100% of the toxic samples were toxic) and nontoxicity (correctly predicted 71% of the nontoxic samples were nontoxic). This analysis clearly shows that direct pore-water measurement is the most accurate chemical method currently available to estimate PAH-contaminated sediment toxicity to H. azteca.

  18. Toxicity of fluorotelomer carboxylic acids to the algae Pseudokirchneriella subcapitata and Chlorella vulgaris, and the amphipod Hyalella azteca.

    Science.gov (United States)

    Mitchell, Rebecca J; Myers, Anne L; Mabury, Scott A; Solomon, Keith R; Sibley, Paul K

    2011-11-01

    Perfluorinated acids (PFAs) have elicited significant global regulatory and scientific concern due to their persistence and global pervasiveness. A source of PFAs in the environment is through degradation of fluorotelomer carboxylic acids (FTCAs) but little is known about the toxicity of these degradation products. Previous work found that FTCAs were two to three orders of magnitude more toxic to some freshwater invertebrates than their PFA counterparts and exhibited comparable chain-length-toxicity relationships. In this study, we investigated the toxicity of the 6:2, 8:2, and 10:2 saturated (FTsCA) and unsaturated (FTuCA) fluorotelomer carboxylic acids to two species of freshwater algae, Chlorella vulgaris and Pseudokirchneriella subcapitata, and the amphipod, Hyalella azteca. C. vulgaris was generally the most sensitive species, with EC₅₀s of 26.2, 31.8, 11.1, and 4.2 mg/L for the 6:2 FTsCA, 6:2 FTuCA, 8:2 FTuCA, and 10:2 FTsCA, respectively. H. azteca was most sensitive to the 8:2 FTsCA and 10:2 FTuCA, with LC₅₀s of 5.1 and 3.7 mg/L. The toxicity of the FTCAs generally increased with increasing carbon chain length, and with saturation for most of the species tested, with the exception of P. subcapitata, which did not exhibit any trend. These observations agree with chain-length-toxicity relationships previously reported for the PFCAs and support the greater toxicity of the FTCAs compared to PFCAs. However, the toxicity values are approximately 1000-fold above those detected in the environment indicating negligible risk to aquatic invertebrates.

  19. USE OF CARBOXYLESTERASE ACTIVITY TO REMOVE PYRETHROID-ASSOCIATED TOXICITY TO CERIODAPHNIA DUBIA AND HYALELLA AZTECA IN TOXICITY IDENTIFICATION EVALUATIONS

    Science.gov (United States)

    Wheelock, Craig E.; Miller, Jeff L.; Miller, Mike J.; Phillips, Bryn M.; Huntley, Sarah A.; Gee, Shirley J.; Tjeerdema, Ronald S.; Hammock, Bruce D.

    2006-01-01

    Increases in the use and application of pyrethroid insecticides have resulted in concern regarding potential effects on aquatic ecosystems. Methods for the detection of pyrethroids in receiving waters are required to monitor environmental levels of these insecticides. One method employed for the identification of causes of toxicity in aquatic samples is the toxicity identification evaluation (TIE); however, current TIE protocols do not include specific methods for pyrethroid detection. Recent work identified carboxylesterase treatment as a useful method for removing/detecting pyrethroid-associated toxicity. The present study has extended this earlier work and examined the ability of carboxylesterase activity to remove permethrin- and bifenthrin-associated toxicity to Ceriodaphnia dubia and Hyalella azteca in a variety of matrices, including laboratory water, Sacramento River (CA, USA) water, and Salinas River (CA, USA) interstitial water. Esterase activity successfully removed 1,000 ng/L of permethrin-associated toxicity and 600 ng/L of bifenthrin-associated toxicity to C. dubia in Sacramento River water. In interstitial water, 200 ng/L of permethrin-associated toxicity and 60 ng/L of bifenthrin-associated toxicity to H. azteca were removed. The selectivity of the method was validated using heat-inactivated enzyme and bovine serum albumin, demonstrating that catalytically active esterase is required. Further studies showed that the enzyme is not significantly inhibited by metals. Matrix effects on esterase activity were examined with municipal effluent and seawater in addition to the matrices discussed above. Results confirmed that the esterase retains catalytic function in a diverse array of matrices, suggesting that this technique can be adapted to a variety of aquatic samples. These data demonstrate the utility of carboxylesterase treatment as a viable step to detect the presence of pyrethroids in receiving waters. PMID:16629136

  20. Comparing the effectiveness of chronic water column tests with the crustaceans Hyalella azteca (order: Amphipoda) and Ceriodaphnia dubia (order: Cladocera) in detecting toxicity of current-use insecticides.

    Science.gov (United States)

    Deanovic, Linda A; Markiewicz, Dan; Stillway, Marie; Fong, Stephanie; Werner, Inge

    2013-03-01

    Standard U.S. Environmental Protection Agency laboratory tests are used to monitor water column toxicity in U.S. surface waters. The water flea Ceriodaphnia dubia is among the most sensitive test species for detecting insecticide toxicity in freshwater environments.Its usefulness is limited, however, when water conductivity exceeds 2,000 µS/cm (approximately 1 ppt salinity) and test effectiveness is insufficient. Water column toxicity tests using the euryhaline amphipod Hyalella azteca could complement C. dubia tests; however, standard chronic protocols do not exist. The present study compares the effectiveness of two water column toxicity tests in detecting the toxicity of two organophosphate (OP) and two pyrethroid insecticides: the short-term chronic C. dubia test, which measures mortality and fecundity, and a 10-d H. azteca test, which measures mortality and growth. Sensitivity was evaluated by comparing effect data, and end point variability was evaluated by comparing minimum significant differences. Tests were performed in synthetic water and filtered ambient water to quantify the influence of water matrix on effect concentrations. The H. azteca test detected pyrethroid toxicity far more effectively, while the C. dubia test was more sensitive to OPs. Among endpoints, H. azteca mortality was most robust. The results demonstrate that the H. azteca test is preferable when conductivity of water samples is 2,000 to 10,000 µS/cm or if contaminants of concern include pyrethroid insecticides.

  1. Environmental fate of pyrethroids in urban and suburban stream sediments and the appropriateness of Hyalella azteca model in determining ecological risk.

    Science.gov (United States)

    Palmquist, Katherine; Fairbrother, Anne; Salatas, Johanna; Guiney, Patrick D

    2011-07-01

    According to several recent studies using standard acute Hyalella azteca sediment bioassays, increased pyrethroid use in urban and suburban regions in California has resulted in the accumulation of toxic concentrations of pyrethroids in sediments of area streams and estuaries. However, a critical review of the literature indicates that this is likely an overestimation of environmental risk. Hyalella azteca is consistently the most susceptible organism to both aqueous and sediment-associated pyrethroid exposures when compared to a suite of other aquatic taxa. In some cases, H. azteca LC50 values are less than the community HC10 values, suggesting that the amphipod is an overly conservative model for community- or ecosystem-level impacts of sediment-associated pyrethroids. Further, as a model for responses of field populations of H. azteca, the laboratory bioassays considerably overestimate exposure, because the amphipod is more appropriately characterized as an epibenthic organism, not a true sediment dweller; H. azteca preferentially inhabit aquatic macrophytes, periphyton mats, and leaf litter, which drastically reduces their exposure to contaminated sediments. Sediment-bound pyrethroids are transported via downstream washing of fine particulates resulting in longer range transport but also more efficient sequestration of the chemical. In addition, site-specific variables such as sediment organic carbon content, grain size, temperature, and microbial activity alter pyrethroid bioavailability, degradation, and toxicity on a microhabitat scale. The type and source of the carbon in particular, influences the pyrethroid sequestering ability of sediments. The resulting irregular distribution of pyrethroids in stream sediments suggests that sufficient nonimpacted habitat may exist as refugia for resident sediment-dwelling organisms for rapid recolonization to occur. Given these factors, we argue that the amphipod model provides, at best, a screening level assessment of

  2. Reduced metals concentrations of water, sediment and hyalella azteca from lakes in the vicinity of the sudbury metal smelters, Ontario, Canada.

    Science.gov (United States)

    Shuhaimi-Othman, M; Pascoe, D; Borgmann, U; Norwood, W P

    2006-06-01

    Hyalella azteca (Crustacea: Amphipoda), water and sediments from 12 circum-neutral lakes between Sudbury and North Bay in Ontario, Canada were sampled in August 1998 and analyzed for 10 metals including Cu, Zn, Cd, Ni, Pb, Co, Mo, V, Ba and Ti. Statistical analyses showed that concentrations of the metals in H. azteca, water and sediment differed significantly (ANOVA, Pazteca and Mo in water). There was a trend of declining metal concentration, especially for Cu, Ni and Co (in water, Hyalella and sediment), with distance from the smelters indicating the reduced impact of atmospheric pollution. Metal concentrations of lakes (water) in the Sudbury area were found to be lower compared to data from the 1970s and 1980s indicating an improvement in water quality. Metal concentrations in field-collected amphipods compared favorably with those measured in the laboratory in animals exposed to deep-water sediments, provided metal concentrations were not extremely low (e.g., Pb) and that water chemistry differences (e.g., pH) were taken into account for some metals (especially Cd). In general bioaccumulation of metals in H. azteca was predicted better from surface water than from sediment total metal.

  3. Single-walled carbon nanotubes toxicity to the freshwater amphipod Hyalella azteca: influence of sediment and exposure duration

    Directory of Open Access Journals (Sweden)

    Messika Revel

    2015-04-01

    Full Text Available Carbon nanomaterials are present in various industrial applications and therefore their release into the environment including freshwater ecosystem is expected to increase. The aim of the present study was to investigate the influence of several parameters on the toxicity of single-walled carbon nanotubes (SWCNT to the freshwater amphipod, Hyalella azteca. The effect of period of exposure, sediment presence and possible impurities released during SWCNT preparation on survival and/or growth of such organism was evaluated. We measured a reduction of survival at concentrations ranging from 10 to 40 mg/L after 96-h exposure, while no mortality was observed with the same concentrations and in the presence of artificial sediment after 14 days of exposure. It is possible that SWCNT are adsorbed on the organic matter from the artificial sediment leading to a decrease of SWCNT bioavailability. The survival and growth toxicity tests revealed a stronger effect at 28 days compared to the 14 days of exposure, and full mortality of organisms at 1000 mg/L for both exposure times. The presence of SWCNT in the gut of survived organisms was observed. The present study demonstrates that the interaction with sediment should be considered when carbon nanotubes toxicity through water exposure is investigated.

  4. Bioaccumulation of metals by Hyalella azteca exposed to contaminated sediments from the upper Clark Fork River, Montana

    Science.gov (United States)

    Ingersoll, Christopher G.; Brumbaugh, William G.; Dwyer, F. James; Kemble, Nile E.

    1994-01-01

    Macroinvertebrates contaminated with metals in the Clark Fork River of Montana have been demonstrated to be a potentially toxic component in the diet of trout Because sediment was the suspected source of metals to these invertebrates, bioaccumulation of As, Cd, Cu, Pb, and Zn from sediment was evaluated by exposing the amphipod Hyalella azteca for 28 d in the laboratory to samples of sediment collected from depositional areas of the Clark Fork River Benthic invertebrates collected from riffles adjacent to the depositional areas were also analyzed for metals The pattern of metal accumulation between laboratory-exposed and field-collected animals was similar, however, the concentrations of metals in laboratory exposed amphipods were often 50 to 75% less than were the concentrations of metals in the field collected invertebrates These findings indicate that sediment is a significant source of metals to invertebrates in the Clark Fork River Additional studies should be conducted to determine threshold concentrations for effects of dietary metals on fish Long-term monitoring of the river should include sampling benthic invertebrates for metal accumulation.

  5. Assessing sediment toxicity from navigational pools of the Upper Mississippi River using a 28-day Hyalella azteca test

    Science.gov (United States)

    Kemble, N.E.; Brunson, E.L.; Canfield, T.J.; Dwyer, F.J.; Ingersoll, C.G.

    1998-01-01

    To assess the extent of sediment contamination in the Upper Mississippi River (UMR) system after the flood of 1993, sediment samples were collected from 24 of the 26 navigational pools in the river and from one site in the Saint Croix River in the summer of 1994. Whole-sediment tests were conducted with the amphipod Hyalella azteca for 28 days measuring the effects on survival, growth, and sexual maturation. Amphipod survival was significantly reduced in only one sediment (13B) relative to the control and reference sediments. Body length of amphipods was significantly reduced relative to the control and reference sediments in only one sample (26C). Sexual maturation was not significantly reduced in any treatment when compared to the control and reference sediments. No significant correlations were observed between survival, growth, and maturation to either the physical or chemical characteristics of the sediment samples from the river. When highly reliable effect range medians (ERMs) were used to evaluate sediment chemistry, 47 of 49 (96%) of the samples were correctly classified as nontoxic. These results indicate that sediment samples from the Upper Mississippi River are relatively uncontaminated compared to other areas of known contamination in the United States.

  6. Using an interlaboratory study to revise methods for conducting 10-d to 42-d water or sediment toxicity tests with Hyalella azteca.

    Science.gov (United States)

    Ivey, Chris D; Ingersoll, Chris G; Brumbaugh, William G; Hammer, Edward J; Mount, Dave R; Hockett, J Russell; Norberg-King, Teresa J; Soucek, Dave; Taylor, Lisa

    2016-10-01

    Studies have been conducted to refine US Environmental Protection Agency, ASTM International, and Environment Canada standard methods for conducting 42-d reproduction tests with Hyalella azteca in water or in sediment. Modifications to the H. azteca method include better-defined ionic composition requirements for exposure water (i.e., >15 mg/L of chloride and >0.02 mg/L of bromide) and improved survival, growth, and reproduction with alternate diets provided as increased rations over time in water-only or whole-sediment toxicity tests. A total of 24 laboratories volunteered to participate in the present interlaboratory study evaluating the performance of H. azteca in 42-d studies in control sand or control sediment using the refined methods. Improved growth and reproduction of H. azteca was observed with 2 alternate diets of 1) ramped diatoms (Thalassiosira weissflogii) + ramped Tetramin or 2) yeast-cerophyll-trout chow (YCT) + ramped Tetramin, especially when compared with results from the traditional diet of 1.8 mg YCT/d. Laboratories were able to meet proposed test acceptability criteria and in most cases had lower variation in growth or reproduction compared with previous interlaboratory studies using the traditional YCT diet. Laboratory success in conducting 42-d H. azteca exposures benefited from adherence to several key requirements of the detailed testing, culturing, and handling methods. Results from the present interlaboratory study are being used to help revise standard methods for conducting 10-d to 42-d water or sediment toxicity exposures with H. azteca. Environ Toxicol Chem 2016;35:2439-2447. © 2016 SETAC.

  7. Using an interlaboratory study to revise methods for conducting 10-d to 42-d water or sediment toxicity tests with Hyalella azteca

    Science.gov (United States)

    Ivey, Chris D.; Ingersoll, Christopher G.; Brumbaugh, William G.; Hammer, Edward J.; Mount, David R.; Hockett, J. Russell; Norberg-King, Teresa J.; Soucek, Dave; Taylor, Lisa

    2016-01-01

    Studies have been conducted to refine US Environmental Protection Agency, ASTM International, and Environment Canada standard methods for conducting 42-d reproduction tests with Hyalella azteca in water or in sediment. Modifications to the H. azteca method include better-defined ionic composition requirements for exposure water (i.e., >15 mg/L of chloride and >0.02 mg/L of bromide) and improved survival, growth, and reproduction with alternate diets provided as increased rations over time in water-only or whole-sediment toxicity tests. A total of 24 laboratories volunteered to participate in the present interlaboratory study evaluating the performance of H. azteca in 42-d studies in control sand or control sediment using the refined methods. Improved growth and reproduction of H. azteca was observed with 2 alternate diets of 1) ramped diatoms (Thalassiosira weissflogii) + ramped Tetramin or 2) yeast–cerophyll–trout chow (YCT) + ramped Tetramin, especially when compared with results from the traditional diet of 1.8 mg YCT/d. Laboratories were able to meet proposed test acceptability criteria and in most cases had lower variation in growth or reproduction compared with previous interlaboratory studies using the traditional YCT diet. Laboratory success in conducting 42-d H. azteca exposures benefited from adherence to several key requirements of the detailed testing, culturing, and handling methods. Results from the present interlaboratory study are being used to help revise standard methods for conducting 10-d to 42-d water or sediment toxicity exposures with H. azteca.

  8. Behavioural alterations from exposure to Cu, phenanthrene, and Cu-phenanthrene mixtures: linking behaviour to acute toxic mechanisms in the aquatic amphipod, Hyalella azteca.

    Science.gov (United States)

    Gauthier, Patrick T; Norwood, Warren P; Prepas, Ellie E; Pyle, Greg G

    2016-01-01

    Phenanthrene (PHE) and Cu are two contaminants commonly co-occurring in marine and freshwater environments. Mixtures of PHE and Cu have been reported to induce more-than-additive lethality in the amphipod, Hyalella azteca, a keystone aquatic invertebrate, yet little is understood regarding the interactive toxic mechanisms that mediate more-than-additive toxicity. Understanding the interactions among toxic mechanisms among Cu and PHE will allow for better predictive power in assessing the ecological risks of Cu-PHE mixtures in aquatic environments. Here we use behavioural impairment to help understand the toxic mechanisms of Cu, PHE, and Cu-PHE mixture toxicity in the aquatic amphipod crustacean, Hyalella azteca. Our principal objective was to link alterations in activity and ventilation with respiratory rates, oxidative stress, and neurotoxicity in adult H. azteca. Adult amphipods were used for all toxicity tests. Amphipods were tested at sublethal exposures of 91.8- and 195-μgL(-1) Cu and PHE, respectively, and a Cu-PHE mixture at the same concentrations for 24h. Neurotoxicity was measured as acetylcholinesterase (AChE) activity, where malathion was used as a positive control. Oxidative stress was measured as reactive oxygen species (ROS) production. Phenanthrene-exposed amphipods exhibited severe behavioural impairment, being hyperstimulated to the extent that they were incapable of coordinating muscle movements. In addition, respiration and AChE activity in PHE-exposed amphipods were increased and reduced by 51% and 23% respectively. However, ROS did not increase following exposure to phenanthrene. In contrast, Cu had no effect on amphipod behaviour, respiration or AChE activity, but did lead to an increase in ROS. However, co-exposure to Cu antagonized the PHE-induced reduction in ventilation and negated any increase in respiration. The results suggest that PHE acts like an organophosphate pesticide (e.g., malathion) in H. azteca following 24h sublethal

  9. Evaluation of ability of reference toxicity tests to identify stress in laboratory populations of the amphipod Hyalella azteca

    Science.gov (United States)

    McNulty, E.W.; Dwyer, F.J.; Ellersieck, Mark R.; Greer, E.I.; Ingersoll, C.G.; Rabeni, C.F.

    1999-01-01

    Standard methods for conducting toxicity tests imply that the condition of test organisms can be established using reference toxicity tests. However, only a limited number of studies have evaluated whether reference toxicity tests can actually be used to determine if organisms are in good condition at the start of a test. We evaluated the ability of reference toxicants to identify stress associated with starvation in laboratory populations of the amphipod Hyalella azteca using acute toxicity tests and four reference toxicants: KCl, CdCl2, sodium pentachlorophenate (NaPCP), and carbaryl. Stress associated with severe starvation was observed with exposure of amphipods to carbaryl or NaPCP but not with exposure to KCl or CdCl2 (i.e., lower LC50 with severe starvation). Although the LC50s for NaPCP and carbaryl were statistically different between starved and fed amphipods, this difference may not be biologically significant given the variability expected in acute lethality tests. Stress associated with sieving, heat shock, or cold shock of amphipods before the start of a test was not evident with exposure to carbaryl or KCl as reference toxicants. The chemicals evaluated in this study provided minimal information about the condition of the organisms used to start a toxicity test. Laboratories should periodically perform reference toxicity tests to assess the sensitivity of life stages or strains of test organisms. However, use of other test acceptability criteria required in standard methods such as minimum survival, growth, or reproduction of organisms in the control treatment at the end of a test, provides more useful information about the condition of organisms used to start a test compared to data generated from reference toxicity tests.

  10. Toxicity of sediment cores collected from the ashtabula river in northeastern Ohio, USA, to the amphipod hyalella azteca

    Science.gov (United States)

    Ingersoll, C.G.; Kemble, N.E.; Kunz, J.L.; Brumbaugh, W.G.; MacDonald, D.D.; Smorong, D.

    2009-01-01

    This study was conducted to support a Natural Resource Damage Assessment and Restoration project associated with the Ashtabula River in Ohio. The objective of the study was to evaluate the chemistry and toxicity of 50 sediment samples obtained from five cores collected from the Ashtabula River (10 samples/core, with each 10-cm-diameter core collected to a total depth of about 150 cm). Effects of chemicals of potential concern (COPCs) measured in the sediment samples were evaluated by measuring whole-sediment chemistry and whole-sediment toxicity in the sediment samples (including polycyclic aromatic hydrocarbons [PAHs], polychlorinated biphenyls [PCBs], organochlorine pesticides, and metals). Effects on the amphipod Hyalella azteca at the end of a 28-day sediment toxicity test were determined by comparing survival or length of amphipods in individual sediment samples in the cores to the range of responses of amphipods exposed to selected reference sediments that were also collected from the cores. Mean survival or length of amphipods was below the lower limit of the reference envelope in 56% of the sediment samples. Concentrations of total PCBs alone in some samples or concentrations of total PAHs alone in other samples were likely high enough to have caused the reduced survival or length of amphipods (i.e., concentrations of PAHs or PCBs exceeded mechanistically based and empirically based sediment quality guidelines). While elevated concentrations of ammonia in pore water may have contributed to the reduced length of amphipods, it is unlikely that the reduced length was caused solely by elevated ammonia (i.e., concentrations of ammonia were not significantly correlated with the concentrations of PCBs or PAHs and concentrations of ammonia were elevated both in the reference sediments and in the test sediments). Results of this study show that PAHs, PCBs, and ammonia are the primary COPCs that are likely causing or substantially contributing to the toxicity to

  11. Evaluation of ability of reference toxicity tests to identify stress in laboratory populations of the amphipod Hyalella azteca

    Energy Technology Data Exchange (ETDEWEB)

    McNulty, E.W.; Ellersieck, M.R.; Rabeni, C.F. [Univ. of Missouri, Columbia, MO (United States); Dwyer, F.J.; Greer, E.I.; Ingersoll, C.G. [Geological Survey, Columbia, MO (United States). Columbia Environmental Research Center

    1999-03-01

    Standard methods for conducting toxicity tests imply that the condition of test organisms can be established using reference toxicity tests. However, only a limited number of studies have evaluated whether reference toxicity tests can actually be used to determine if organisms are in good condition, at the start of a test. The authors evaluated the ability of reference toxicants to identify stress associated with starvation in laboratory populations of the amphipod Hyalella azteca using acute toxicity tests and four reference toxicants: KCl, CdCl{sub 2}, sodium pentachlorophenate (NaPCP), and carbaryl. Stress associated with severe starvation was observed with exposure of amphipods to carbaryl or NaPCP but not with exposure to KCl or CdCl{sub 2} (i.e., lower LC50 with severe starvation). Although the LC50s for NaPCP and carbaryl were statistically different between starved and fed amphipods, this difference may not be biologically significant given the variability expected in acute lethality tests. Stress associated with sieving, heat shock, or cold shock of amphipods before the start of a test was not evident with exposure to carbaryl or KCl as reference toxicants. The chemicals evaluated in this study provided minimal information about the condition of the organisms used to start a toxicity test. Laboratories should periodically perform reference toxicity tests to assess the sensitivity of life stages or strains of test organisms. However, use of other test acceptability criteria required in standard methods, such as minimum survival, growth, or reproduction of organisms in the control treatment at the end of a test, provides more useful information about the condition of organisms used to start a test compared to data generated from reference toxicity tests.

  12. A comparative study of different diets to optimize cultivation of Hyalella azteca in the laboratory.

    Science.gov (United States)

    Fracácio, Renata; Dias, Geisa Soares; Zagatto, Pedro Antônio; Bidinotto, Paulo Maurício; Silva, Paulo

    2011-09-01

    The aim of this study was to assess the influence of four diets on the laboratory cultivation of H. azteca, seeking to improve production of young specimens through reduced mortality and better growth and number of offspring per couple. The best diet was composed of a mixture of diluted commercial fish food, diluted yeast and primrose oil, associated with fish food flakes containing spirulina. With this diet the maximum mortality was 25 percent (at the end of 28 days), the average number of offspring/couple was 11.4 ± 2.8 (at the end of twelve days) and the peak weight and length of the males (at the end of 40 days) were 0.930 μg and 5.26 ± 1.1mm, respectively.

  13. A two-step experimental design for a sediment bioassay using growth of the amphipod Hyalella azteca for the test end point

    Science.gov (United States)

    Kubitz, Jody A.; Besser, John M.; Giesy, John P.

    1996-01-01

    We designed a sediment bioassay using 25% growth inhibition of Hyalella azteca as the end point.Hyalella azteca exhibits size-specific fecundity, so growth is a surrogate of reproductive production. We investigated density effects on growth to address whether crowding could affect test interpretation; amphipods in 14,000/m2 exposures were 16 to 20% smaller than those at 7,000/m2. Using power analysis, we found that 20 to 25 samples are required to determine significance when α = 0.10 and 1 − β = 0.90. To minimize the need for laboratory resources, we designed a two-step (screening and confirmatory) bioassay, which we tested with field-collected sediments. The screening bioassay compared 11 sediments to a reference. Three sediments were “toxic” (significant growth inhibition when 1 − β = 0.66 and n = 5), five sediments were “nontoxic” (>90% of reference), and three sediments were “possibly toxic” (growth inhibition was insignificant). In the confirmatory bioassay, three possibly toxic and two nontoxic samples were reevaluated. Two were toxic (1 − β = 0.91 and n = 20), and the remaining four samples were nontoxic. In summary, five sediments were toxic and six sediments were nontoxic. The two-step analysis used minimal laboratory resources but maximized statistical power, where needed, to discriminate growth effects.

  14. Selection of food combinations to optimize survival, growth, and reproduction of the amphipod Hyalella azteca in static-renewal, water-only laboratory exposures.

    Science.gov (United States)

    Soucek, David J; Dickinson, Amy; Major, Kaley M

    2016-10-01

    Although standardized sediment toxicity testing methods have been developed for the amphipod Hyalella azteca, no standardized chronic water-only toxicity testing methods have been established. Furthermore, optimal feeding and water quality conditions for culturing and toxicity testing with this species remained unclear. The objective of the present study was to determine the food or combination of foods that best promotes survival, growth, and reproduction of the US Lab strain of Hyalella azteca under 42-d, water-only, static-renewal testing conditions. The authors conducted 7 42-d control (no toxicant) tests with various combinations of food (including Tetramin, yeast-cereal leaves-trout chow, diatoms, wheatgrass, alfalfa, and maple leaves) and substrate types (clean "unconditioned" Nitex screens vs "conditioned" Nitex screens that were colonized by live biofilms). Over all treatments, survival ranged from 18% to 96%, dry weight per individual from 0.084 mg to 1.101 mg, and reproduction from 0 young/female to 28.4 young/female. Treatments that included Tetramin tended to result in better performance than those that did not. In particular, treatments that included Tetramin and either conditioned screens or diatoms consistently had high survival, weight, and reproduction values as well as low variability among replicates (measured as coefficient of variation). A ramped Tetramin plus diatom suspension feeding regime appears to have the greatest potential to produce consistently good performance across laboratories using static-renewal systems. Environ Toxicol Chem 2016;35:2407-2415. © 2016 SETAC.

  15. Implications of Cu and Ni toxicity in two members of the Hyalella azteca cryptic species complex: Mortality, growth, and bioaccumulation parameters.

    Science.gov (United States)

    Leung, Jessica; Witt, Jonathan D S; Norwood, Warren; Dixon, D George

    2016-11-01

    Hyalella azteca, an amphipod crustacean, is frequently used in freshwater toxicity tests. Since the mid-1980s, numerous organizations have collected and established cultures of H. azteca originating from localities across North America. However, H. azteca is actually a large cryptic species complex whose members satisfy both the biological and the phylogenetic species concepts. Genetic analysis at the mitochondrial COI gene has revealed that only 2 clades are cultured in 17 North American laboratories; however, there are 85 genetically divergent lineages within this complex in the wild. In the present study, 2 members (clades 1 and 8) of the H. azteca species complex were identified using the mitochondrial COI gene. These 2 clades were exposed to Cu or Ni for 14 d. A saturation-based mortality model and the general growth model were used to determine mortality (lethal concentration, 25% and 50% [LC25 and LC50], lethal body concentration, 25% and 50% [LBC25 and LBC50]) and growth (inhibitory concentration, 25% [IC25, IBC25]) endpoints, respectively. A modified saturation-based model was used to estimate metal bioaccumulation parameters. Clade 8 was significantly more tolerant than clade 1, with differences in LC50s. However, the effects of the metals on growth were not significantly different between clades, even though clade 1 was significantly larger than then clade 8. Differences in Cu or Ni bioaccumulation were not observed between clades 1 and 8. The differences in Cu and Ni LC50s may have implications for risk assessments, and it is recommended that toxicity experiments should only be performed with properly identified members of the H. azteca complex to maintain consistency among laboratories. Environ Toxicol Chem 2016;35:2817-2826. © 2016 SETAC.

  16. Contaminants in stream sediments from seven United States metropolitan areas: part II—sediment toxicity to the amphipod Hyalella azteca and the midge Chironomus dilutus

    Science.gov (United States)

    Kemble, Nile E.; Hardesty, Douglas K.; Ingersoll, Christopher G.; Kunz, James L.; Sibley, Paul K.; Calhoun, Daniel L.; Gilliom, Robert J.; Kuivila, Kathryn; Nowell, Lisa H.; Moran, Patrick W.

    2013-01-01

    Relationships between sediment toxicity and sediment chemistry were evaluated for 98 samples collected from seven metropolitan study areas across the United States. Sediment-toxicity tests were conducted with the amphipod Hyalella azteca (28 day exposures) and with the midge Chironomus dilutus (10 day exposures). Overall, 33 % of the samples were toxic to amphipods and 12 % of the samples were toxic to midge based on comparisons with reference conditions within each study area. Significant correlations were observed between toxicity end points and sediment concentrations of trace elements, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), or organochlorine (OC) pesticides; however, these correlations were typically weak, and contaminant concentrations were usually below sediment-toxicity thresholds. Concentrations of the pyrethroid bifenthrin exceeded an estimated threshold of 0.49 ng/g (at 1 % total organic carbon) in 14 % of the samples. Of the samples that exceeded this bifenthrin toxicity threshold, 79 % were toxic to amphipods compared with 25 % toxicity for the samples below this threshold. Application of mean probable effect concentration quotients (PECQs) based on measures of groups of contaminants (trace elements, total PAHs, total PCBs,OCpesticides, and pyrethroid pesticides [bifenthrin in particular]) improved the correct classification of samples as toxic or not toxic to amphipods compared with measures of individual groups of contaminants. Sediments are a repository for many contaminants released into surface waters. Because of this, organisms inhabiting sediments may be exposed to a wide range of contaminants (United States Environmental Protection Agency (USEPA) United States Environmental Protection Agency 2000; American Society for Testing and Materials [ASTM] American Society for Testing and Materials International 2012). Contaminants of potential concern in sediments typically include trace elements (metals

  17. The role of metabolism in the toxicity of 2,4,6-trinitrotoluene and its degradation products to the aquatic amphipod Hyalella azteca.

    Science.gov (United States)

    Sims, Jerre G; Steevens, Jeffery A

    2008-05-01

    Toxicological data on the effects of the explosive, 2,4,6-trinitrotoluene (TNT), and its degradation products suggests an unpredictable toxicological response in aquatic organisms. Several studies suggest TNT becomes more toxic as it degrades while others suggest TNT becomes less toxic. This study focused on the toxicity of TNT and several degradation products as well as the role of oxidative metabolism in the toxicity of TNT. The aquatic invertebrate Hyalella azteca was used to evaluate the toxicity of TNT and four of its degradation products. The most reduced degradation product, 2,4-diamino, 6-nitrotoluene (2,4-DANT) was the most toxic to H. azteca. However, 2,4-DANT was only a minor metabolite in H. azteca. The influence of metabolism on the toxicokinetics of TNT was assessed indirectly through the use of a CYP450 inducer and inhibitor. Treatment of organisms with beta-napthoflavone (BNF), a CYP450 inducer, increased the toxicity of TNT and increased the rate of elimination and metabolism of TNT. Similar to BNF, organisms treated with clotrimazole (CTZ), a CYP450 inhibitor, resulted in increased toxicity and TNT metabolism. It is likely the ability to metabolize or bioactivate TNT to a more reactive intermediate plays a significant role in the sensitivity of organisms to TNT.

  18. Causes of toxicity to Hyalella azteca in a stormwater management facility receiving highway runoff and snowmelt. Part I: polycyclic aromatic hydrocarbons and metals.

    Science.gov (United States)

    Bartlett, A J; Rochfort, Q; Brown, L R; Marsalek, J

    2012-01-01

    The Terraview-Willowfield Stormwater Management Facility (TWSMF) receives inputs of multiple contaminants, including metals, polycyclic aromatic hydrocarbons (PAHs), road salt, and nutrients, via highway and residential runoff. Contaminant concentrations in runoff are seasonally dependent, and are typically high in early spring, coinciding with the snowmelt. In order to investigate the seasonal fluctuations of contaminant loading and related changes in toxicity to benthic invertebrates, overlying water and sediment samples were collected in the fall and spring, reflecting low and high contaminant loading, respectively, and four-week sediment toxicity tests were conducted with Hyalella azteca. The effects of metals and PAHs are discussed here; the effects of salts, nutrients, and water quality are discussed in a companion paper. Survival and growth of Hyalella after exposure to fall samples were variable: survival was significantly reduced (64-74% of controls) at three out of four sites, but there were no significant growth effects. More dramatic effects were observed after Hyalella were exposed to spring samples: survival was significantly reduced at the two sites furthest downstream (0-75% of controls), and growth was significantly lower in four out of five sites when comparing Hyalella exposed to site sediment with overlying site water versus site sediment with overlying control water. These seasonal changes in toxicity were not related to metals or PAHs: 1. levels of bioavailable metals were below those expected to cause toxicity, and 2. levels of PAHs in sediment were lowest at sites with the greatest toxicity and highest in water and sediment at sites with no toxicity. Although not associated with toxicity, some metals and PAHs exceeded probable and severe effect levels, and could be a cause for concern if contaminant bioavailability changes. Toxicity in the TWSMF appeared to be primarily associated with water-borne contaminants. The cause(s) of these effects

  19. Predicting toxicity to Hyalella azteca in pyrogenic-impacted sediments-Do we need to analyze for all 34 PAHs?

    Science.gov (United States)

    Geiger, Stephen C; Azzolina, Nicholas A; Nakles, David V; Hawthorne, Steven B

    2016-07-01

    Polycyclic aromatic hydrocarbons (PAHs) are major drivers of risk at many urban and/or industrialized sediment sites. The US Environmental Protection Agency (USEPA) currently recommends using measurements of 18 parent + 16 groups of alkylated PAHs (PAH-34) to assess the potential for sediment-bound PAHs to impact benthic organisms at these sites. ASTM Method D7363-13 was developed to directly measure low-level sediment porewater PAH concentrations. These concentrations are then compared to ambient water criteria (final chronic values [FCVs]) to assess the potential for impact to benthic organisms. The interlaboratory validation study that was used to finalize ASTM D7363-13 was developed using 24 of the 2-, 3-, and 4-ring PAHs (PAH-24) that are included in the USEPA PAH-34 analyte list. However, it is the responsibility of the user of ASTM Method D7363 to establish a test method to quantify the remaining 10 higher molecular weight PAHs that make up PAH-34. These higher molecular weight PAHs exhibit extremely low saturation solubilities that make their detection difficult in porewater, which has proven difficult to implement in a contract laboratory setting. As a result, commercial laboratories are hesitant to conduct the method on the entire PAH-34 analyte list. This article presents a statistical comparison of the ability of the PAH-24 and PAH-34 porewater results to predict survival of the freshwater amphipod Hyalella azteca, using the original 269 sediment samples used to gain ASTM D7363 Method approval. The statistical analysis shows that the PAH-24 are statistically indistinguishable from the PAH-34 for predicting toxicity. These results indicate that the analysis of freely dissolved porewater PAH-24 is sufficient for making risk-based decisions based on benthic invertebrate toxicity (survival and growth). This reduced target analyte list should result in a cost-saving for stakeholders and broader implementation of the method at PAH-impacted sediment sites

  20. Mixture toxicity of imidacloprid and cyfluthrin to two non-target species, the fathead minnow Pimephales promelas and the amphipod Hyalella azteca.

    Science.gov (United States)

    Lanteigne, Michelle; Whiting, Sara A; Lydy, Michael J

    2015-02-01

    Two species, the fathead minnow Pimephales promelas and the amphipod Hyalella azteca, were tested to examine acute toxicity to two insecticides, cyfluthrin and imidacloprid individually and as a mixture. Cyfluthrin was acutely toxic to P. promelas and H. azteca with EC50 values and 95 % confidence intervals of 0.31 µg L(-1) (0.26-0.35 µg L(-1)) and 0.0015 µg L(-1) (0.0011-0.0018 µg L(-1)), respectively. Imidacloprid was not acutely toxic to P. promelas at water concentrations ranging from 1 to 5000 µg L(-1), whereas it was toxic to H. azteca with a EC50 value of 33.5 µg L(-1) (23.3-47.4 µg L(-1)). For the P. promelas mixture test, imidacloprid was added at a single concentration to a geometric series of cyfluthrin concentrations bracketing the EC50 value. A synergistic ratio (SR) of 1.9 was found for P. promelas, which was calculated using the cyfluthrin-only exposure and mixture-exposure data. Because cyfluthrin and imidacloprid were toxic to H. azteca, the mixture test was designed based on an equipotent toxic unit method. Results from the mixture test indicated a model deviation ratio (MDR) of 1.7 or 2.7 depending on the model. Mixture test results from the simultaneous exposure to cyfluthrin and imidacloprid with both species indicated a greater than expected toxic response because the SR or MDR values were >1. Because these two insecticides are commonly used together in the same product formulations, nontarget species could be more affected due to their greater-than-additive toxicity observed in the current study.

  1. Direct and indirect toxicity of the fungicide pyraclostrobin to Hyalella azteca and effects on leaf processing under realistic daily temperature regimes.

    Science.gov (United States)

    Willming, Morgan M; Maul, Jonathan D

    2016-04-01

    Fungicides in aquatic environments can impact non-target bacterial and fungal communities and the invertebrate detritivores responsible for the decomposition of allochthonous organic matter. Additionally, in some aquatic systems daily water temperature fluctuations may influence these processes and alter contaminant toxicity, but such temperature fluctuations are rarely examined in conjunction with contaminants. In this study, the shredding amphipod Hyalella azteca was exposed to the fungicide pyraclostrobin in three experiments. Endpoints included mortality, organism growth, and leaf processing. One experiment was conducted at a constant temperature (23 °C), a fluctuating temperature regime (18-25 °C) based on field-collected data from the S. Llano River, Texas, or an adjusted fluctuating temperature regime (20-26 °C) based on possible climate change predictions. Pyraclostrobin significantly reduced leaf shredding and increased H. azteca mortality at concentrations of 40 μg/L or greater at a constant 23 °C and decreased leaf shredding at concentrations of 15 μg/L or greater in the fluctuating temperatures. There was a significant interaction between temperature treatment and pyraclostrobin concentration on H. azteca mortality, body length, and dry mass under direct aqueous exposure conditions. In an indirect exposure scenario in which only leaf material was exposed to pyraclostrobin, H. azteca did not preferentially feed on or avoid treated leaf disks compared to controls. This study describes the influence of realistic temperature variation on fungicide toxicity to shredding invertebrates, which is important for understanding how future alterations in daily temperature regimes due to climate change may influence the assessment of ecological risk of contaminants in aquatic ecosystems.

  2. Use of GC × GC/TOF-MS and LC/TOF-MS for metabolomic analysis of Hyalella azteca chronically exposed to atrazine and its primary metabolite, desethylatrazine.

    Science.gov (United States)

    Ralston-Hooper, Kimberly J; Adamec, Jiri; Jannash, Amber; Mollenhauer, Robert; Ochoa-Acuña, Hugo; Sepúlveda, Maria S

    2011-07-01

    Atrazine is one of the most commonly detected contaminants in the U.S. Little information is available on one of atrazine's metabolites, desethylatrazine (DEA). Two-dimensional gas chromatography and liquid chromatography coupled with time of flight- mass spectrometry were used to examine metabolite profiles of Hyalella azteca chronically exposed to 30 µg/L atrazine and DEA. The majority of identified metabolites were by-products of β-oxidation of fatty acids suggesting possible disruption in energy metabolism. Eicosanoids increased in exposed females suggesting possible perturbations in neuropeptide hormonal systems. Overall, this research demonstrates the feasibility of utilizing metabolomic profiling of invertebrate species exposed to environmental contaminants as a way to determine mechanisms of toxicity.

  3. Survival, growth, and body residues of hyalella azteca (Saussure) exposed to fipronil contaminated sediments from non-vegetated and vegetated microcosms.

    Science.gov (United States)

    Kröger, Robert; Lizotte, Richard E; Moore, Matthew T

    2009-09-01

    We assessed chronic effects of fipronil and metabolite contaminated sediments from non-vegetated and Thallia dealbata vegetated wetland microcosms on Hyalella azteca during wet and dry exposures. Mean sediment concentrations (ng g(-1)) ranged from 0.72-1.26, 0.01-0.69, 0.07-0.23, and 0.49-7.87 for fipronil, fipronil-sulfide, fipronil-sulfone, and fipronil-desulfinyl, respectively. No significant differences in animal survival or growth were observed between non-vegetated and vegetated microcosms during wet or dry exposures. Mean animal body residue concentrations (ng g(-1)) ranged from 28.4-77.6, 0-30.7, and 8.3-43.8 for fipronil, fipronil-sulfide, and fipronil-sulfone. Fipronil-desulfinyl was not detected in any animal samples.

  4. Chronic TiO{sub 2} nanoparticle exposure to a benthic organism, Hyalella azteca: impact of solar UV radiation and material surface coatings on toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Wallis, Lindsay K. [Office of Research and Development, Mid-Continent Ecology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Duluth, MN, 55804 (United States); Diamond, Stephen A. [Nanosafe Inc., Blacksburg, VA, 24060 (United States); Ma, Hongbo [University of Wisconsin-Milwaukee, Zilber School of Public Health, Milwaukee, WI, 53211 (United States); Hoff, Dale J. [Office of Research and Development, Mid-Continent Ecology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Duluth, MN, 55804 (United States); Al-Abed, Souhail R. [National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, OH 45268 (United States); Li, Shibin, E-mail: lishibinepa@gmail.com [Office of Research and Development, Mid-Continent Ecology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Duluth, MN, 55804 (United States)

    2014-11-15

    There is limited information on the chronic effects of nanomaterials to benthic organisms, as well as environmental mitigating factors that might influence this toxicity. The present study aimed to fill these data gaps by examining various growth endpoints (weight gain, instantaneous growth rate, and total protein content) for up to a 21 d sediment exposure of TiO{sub 2} nanoparticles (nano-TiO{sub 2}) to a representative benthic species, Hyalella azteca. An uncoated standard, P25, and an Al(OH){sub 3} coated nano-TiO{sub 2} used in commercial products were added to sediment at 20 mg/L or 100 mg/L Under test conditions, UV exposure alone was shown to be a greater cause of toxicity than even these high levels of nano-TiO{sub 2} exposure, indicating that different hazards need to be addressed in toxicity testing scenarios. In addition, this study showed the effectiveness of a surface coating on the decreased photoactivity of the material, as the addition of an Al(OH){sub 3} coating showed a dramatic decrease in reactive oxygen species (ROS) production. However, this reduced photoactivity was found to be partially restored when the coating had been degraded, leading to the need for future toxicity tests which examine the implications of weathering events on particle surface coatings. - Highlights: • Chronic toxicity of nano-TiO{sub 2} to a benthic organism (Hyalella azteca) was examined. • Phototoxicity was investigated through exposure of solar simulated radiation (SSR). • The degradation of a surface coating resulted in an increase in photoactivity. • In this testing scenario, UV had a larger impact than chemical exposure in toxicity.

  5. Toxicity of uranium, molybdenum, nickel, and arsenic to Hyalella azteca and Chironomus dilutus in water-only and spiked-sediment toxicity tests.

    Science.gov (United States)

    Liber, Karsten; Doig, Lorne E; White-Sobey, Suzanne L

    2011-07-01

    A series of laboratory spiked-sediment toxicity tests with the amphipod Hyalella azteca and the midge Chironomus dilutus were undertaken to determine acute and chronic toxicity thresholds for uranium (U), molybdenum (Mo), nickel (Ni), and arsenic (As) based on both whole-sediment (total) and pore water exposure concentrations. Water-only toxicity data were also generated from separate experiments to determine the toxicities of these metals/metalloids under our test conditions and to help evaluate the hypothesis that pore water metal concentrations are better correlated with sediment toxicity to benthic organisms than whole-sediment metal concentrations. The relative toxicity of the four elements tested differed depending on which test species was used and whether whole-sediment or pore water metal concentrations were correlated with effects. Based on measured whole-sediment concentrations, Ni and As were the two most acutely toxic elements to H. azteca with 10-d LC50s of 521 and 532 mg/kg d.w., respectively. Measured pore water concentrations indicated that U and Ni were the two most acutely toxic elements, with 10-d LC50s to H. azteca of 2.15 and 2.05 mg/L, respectively. Based on pore water metal concentrations, the no-observed-effect concentrations (NOECs) for growth were (H. azteca and C. dilutus, respectively) 0.67 and 0.21 mg/L for U, azteca and C. dilutus, respectively) 2.99 and 0.48 mg/L for U, 0.37 and 2.33 mg/L for Ni, and 58.99 and 0.42 mg/L for As. For U and Ni, results from 96-h water-only acute toxicity tests correlated well with pore water metal concentrations in acutely toxic metal-spiked sediment. This was not true for As where metalloid concentrations in overlying water (diffusion from sediment) may have contributed to toxicity. The lowest whole-sediment LOEC reported here for As was 6.6- and 4-fold higher than the Canadian Council of Ministers of the Environment interim sediment quality guideline and the Canadian Nuclear Safety Commission (CNSC

  6. Variation in the toxicity of sediment-associated substituted phenylamine antioxidants to an epibenthic (Hyalella azteca) and endobenthic (Tubifex tubifex) invertebrate.

    Science.gov (United States)

    Prosser, R S; Bartlett, A J; Milani, D; Holman, E A M; Ikert, H; Schissler, D; Toito, J; Parrott, J L; Gillis, P L; Balakrishnan, V K

    2017-08-01

    Substituted phenylamine antioxidants (SPAs) are produced in relatively high volumes and used in a range of applications (e.g., rubber, polyurethane); however, little is known about their toxicity to aquatic biota. Therefore, current study examined the effects of chronic exposure (28 d) to four sediment-associated SPAs on epibenthic (Hyalella azteca) and endobenthic (Tubifex tubifex) organisms. In addition, acute (96-h), water-only exposures were conducted with H. azteca. Mortality, growth and biomass production were assessed in juvenile H. azteca exposed to diphenylamine (DPA), N-phenyl-1-napthylamine (PNA), N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine (DPPDA), or 4,4'-methylene-bis[N-sec-butylaniline] (MBA). Mortality of adult T. tubifex and reproduction were assessed following exposure to the four SPAs. The 96-h LC50s for juvenile H. azteca were 1443, 109, 250, and >22 μg/L and 28-d LC50s were 22, 99, 135, and >403 μg/g dry weight (dw) for DPA, PNA, DPPDA, and MBA, respectively. Reproductive endpoints for T. tubifex (EC50s for production of juveniles > 500 μm: 15, 9, 4, 3.6 μg/g dw, for DPA, PNA, DPPDA, and MBA, respectively) were an order of magnitude more sensitive than endpoints for juvenile H. azteca and mortality of adult worms. The variation in toxicity across the four SPAs was likely related to the bioavailability of the sediment-associated chemicals, which was determined by the chemical properties of the SPAs (e.g., solubility in water, Koc). The variation in the sensitivity between the two species was likely due to differences in the magnitude of exposure, which is a function of the life histories of the epibenthic amphipod and the endobenthic worm. The data generated from this study will support effect characterization for ecological risk assessment. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  7. Binary mixtures of diclofenac with paracetamol, ibuprofen, naproxen, and acetylsalicylic acid and these pharmaceuticals in isolated form induce oxidative stress on Hyalella azteca.

    Science.gov (United States)

    Gómez-Oliván, Leobardo Manuel; Neri-Cruz, Nadia; Galar-Martínez, Marcela; Islas-Flores, Hariz; García-Medina, Sandra

    2014-11-01

    Toxicity in natural ecosystems is usually not due to exposure to a single substance, but is rather the result of exposure to mixtures of toxic substances. Knowing the effects of contaminants as a mixture compared to their effects in isolated form is therefore important. This study aimed to evaluate the oxidative stress induced by binary mixtures of diclofenac with paracetamol, ibuprofen, naproxen, and acetylsalicylic acid and by these nonsteroidal anti-inflammatory drugs (NSAIDs) in isolated form, using Hyalella azteca as a bioindicator. The median lethal concentration (LC50) and the lowest observed adverse effect level (LOAEL) of each NSAID were obtained. Amphipods were exposed for 72 h to the latter value in isolated form and as binary mixtures. The following biomarkers were evaluated: lipid peroxidation (LPX), protein carbonyl content (PCC), and activity of the antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Significant increases in LPX and PCC with respect to the control group (p ≤ 0.05) were induced by NSAIDs both in isolated form and as binary mixtures. Changes in SOD, CAT, and GPx activity likewise occurred with NSAIDs in isolated form and as binary mixtures. In conclusion, NSAIDs used in this study induce oxidative stress on H. azteca both in isolated form and as binary mixtures, and the interactions occurring between these pharmaceuticals are probably antagonistic in type.

  8. History and sensitivity comparison of two standard whole-sediment toxicity tests with crustaceans: the amphipod Hyalella azteca and the ostracod Heterocypris incongruens microbiotest

    Directory of Open Access Journals (Sweden)

    De Cooman W.

    2015-01-01

    Full Text Available The review first details the development of the test procedures with Hyalella azteca which historically emerged as one of the recommended test species for whole-sediment assays and its gradual standardization and endorsement by national and international organizations. The sensitivity and precision of the H. azteca test for application on chemicals and on real world sediments is discussed. The review subsequently addresses the development of the whole sediment microbiotest with the ostracod crustacean Heterocypris incongruens with larvae of this test species hatched from dormant eggs (cysts, rendering this assay stock culture/maintenance free. The application of the 6-day ostracod microbiotest on sediments in Canada and in Belgium is discussed, as well as its endorsement by the ISO subsequent to an extensive international interlaboratory ring test. The sensitivity of the amphipod and ostracod tests is compared by data from studies in which both assays were applied in parallel. A comparison of more than 1000 ostracod/amphipod data pairs of a 12-year river sediment monitoring study in Flanders/Belgium confirmed that both whole-sediment assays have a similar sensitivity and that the 6-day ostracod microbiotest is a valuable and cost-effective alternative to the 10−14 day amphipod test for evaluation of the toxic hazard of polluted sediments.

  9. Monitoring acute and chronic water column toxicity in the Northern Sacramento-San Joaquin Estuary, California, USA, using the euryhaline amphipod, Hyalella azteca: 2006 to 2007.

    Science.gov (United States)

    Werner, Inge; Deanovic, Linda A; Markiewicz, Dan; Khamphanh, Manisay; Reece, Charles K; Stillway, Marie; Reece, Charissa

    2010-10-01

    After the significant population decline of several pelagic fish species in the Northern Sacramento-San Joaquin (SSJ) Estuary (CA, USA) in 2002, a study was performed to monitor water column toxicity using the amphipod Hyalella azteca. From January 1, 2006 to December 31, 2007, water samples were collected biweekly from 15 to 16 sites located in large delta channels and main-stem rivers, selected based on prevalent distribution patterns of fish species of concern. Ten-day laboratory tests with H. azteca survival and relative growth as toxicity endpoints were conducted. The enzyme inhibitor piperonyl butoxide ([PBO], 25 µg/L) was added to synergize or antagonize pyrethroid or organophosphate (OP) insecticide toxicity, respectively. Significant amphipod mortality was observed in 5.6% of ambient samples. Addition of PBO significantly changed survival or growth in 1.1% and 10.1% of ambient samples, respectively. Sites in the Lower Sacramento River had the largest number of acutely toxic samples, high occurrence of PBO effects on amphipod growth (along with sites in the South Delta), and the highest total ammonia/ammonium concentrations (0.28 ± 0.15 mg/L). Ammonia/ammonium, or contaminants occurring in mixture with these, likely contributed to the observed toxicity. Pyrethroid insecticides were detected at potentially toxic concentrations. Overall, results of this study identified specific areas and contaminants of concern and showed that water in the Northern SSJ Estuary was at times acutely toxic to sensitive invertebrates.

  10. ACUTE AND CHRONIC TOXICITY OF ALUMINUM TO A UNIONID MUSSEL (LAMPSILIS SILIQUOIDEA) AND AN AMPHIPOD (HYALELLA AZTECA) IN WATER-ONLY EXPOSURES.

    Science.gov (United States)

    Wang, Ning; Ivey, Chris D; Brunson, Eric L; Cleveland, Danielle; Ingersoll, Chris G; Stubblefield, William A; Cardwell, Allison S

    2017-05-05

    The US Environmental Protection Agency (USEPA) is reviewing the protectiveness of the national ambient water quality criteria (WQC) for aluminum (Al) and compiling a toxicity dataset to update the WQC. Freshwater mussels are one of the most imperiled groups of animals in the world, but little is known about the sensitivity of mussels to Al. The objective of the present study was to evaluate acute 96-h and chronic 28-d toxicity of Al to a unionid mussel (Lampsilis siliquoidea) and a commonly tested amphipod (Hyalella azteca) at a pH of 6 and water hardness of 100 mg/L as CaCO3 . Acute 50% effect concentration (EC50) for survival of both species was >6,200 µg total Al/L. The EC50 was greater than all acute values in the USEPA acute Al dataset for freshwater species at pH range of 5.0 to azteca) as the 5th most sensitive species, indicating the two species were sensitive to Al in chronic exposures. The USEPA proposed acute and chronic WQC for Al would adequately protect the mussel and amphipod tested; however, inclusion of the chronic data from the present study and recalculation of the chronic criterion would likely lower the proposed chronic criterion. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  11. Causes of toxicity to Hyalella azteca in a stormwater management facility receiving highway runoff and snowmelt. Part II: salts, nutrients, and water quality.

    Science.gov (United States)

    Bartlett, A J; Rochfort, Q; Brown, L R; Marsalek, J

    2012-01-01

    The Terraview-Willowfield Stormwater Management Facility (TWSMF) features a tandem of stormwater management ponds, which receive inputs of multiple contaminants from highway and residential runoff. Previous research determined that benthic communities in the ponds were impacted by poor habitat quality, due to elevated sediment concentrations of metals and polycyclic aromatic hydrocarbons (PAHS), and salinity in the overlying water, but did not address seasonal changes, including those caused by the influx of contaminants with the snowmelt. In order to address this issue, water and sediment samples were collected from the TWSMF during the fall and spring, and four-week sediment toxicity tests were conducted with Hyalella azteca. The effects of metals and PAHs are discussed in a companion paper; the effects of road salt, nutrients, and water quality are discussed here. After exposure to fall samples, survival of Hyalella was reduced (64-74% of controls) at three out of four sites, but growth was not negatively affected. After exposure to spring samples, survival was 0-75% of controls at the two sites furthest downstream, and growth was significantly lower in four out of five sites when comparing Hyalella exposed to site water overlying site sediment versus control water overlying site sediment. Toxicity appeared to be related to chloride concentrations: little or no toxicity occurred in fall samples (200 mg Cl(-)/L), and significant effects on survival and growth occurred in spring samples above 1550 mg Cl(-)/L and 380 mg Cl(-)/L, respectively. Sodium chloride toxicity tests showed similar results: four-week LC50s and EC25s (growth) were 1200 and 420 mg Cl(-)/L, respectively. Although water quality and nutrients were associated with effects observed in the TWSMF, chloride from road salt was the primary cause of toxicity in this study. Chloride persists during much of the year at concentrations representing a significant threat to benthic communities in the TWSMF.

  12. Acute and chronic toxicity of imidacloprid to the aquatic invertebrates Chironomus tentans and Hyalella azteca under constant- and pulse-exposure conditions.

    Science.gov (United States)

    Stoughton, Sarah J; Liber, Karsten; Culp, Joseph; Cessna, Allan

    2008-05-01

    The toxicity of imidacloprid, a nicotinic mimic insecticide, to the aquatic invertebrates Chironomus tentans and Hyalella azteca, was first evaluated in static 96-hour tests using both technical material (99.2% pure) and Admire, a commercially available formulated product (240 g a.i. L(-1)). The 96-h lethal concentration (LC)50 values for technical imidacloprid and Admire were 65.43 and 17.44 microg/L, respectively, for H. azteca, and 5.75 and 5.40 microg/L, respectively, for C. tentans. Admire was subsequently used in 28-day chronic tests with both species. Exposure scenarios consisted of a constant- and a pulse-exposure regime. The pulse exposure lasted for four days, after which time the animals were transferred to clean water for the remaining 24 days of the study. Assessments were made on both day 10 and day 28. In the C. tentans under constant exposure, larval growth on day 10 was significantly reduced at 3.57 microg/L imidacloprid, the lowest-observed-effect concentration (LOEC). The no-observed-effect concentration (NOEC) and LOEC for the 28-day exposure duration (adult survival and emergence) were 1.14 and greater than 1.14 mug/L, respectively; the associated LC50 and LC25 were 0.91 and 0.59 microg/L, respectively. The LOEC for the pulse treatment was greater than 3.47 microg/L, but the day 10 LC25 was 3.03 microg/L. In the H. azteca tests, the day 10 and 28 constant exposure, as well as the day 28 pulse exposure, LOEC (survival) values were similar at 11.95, 11.46, and 11.93 microg/L, respectively. The day 10 and 28 constant exposure effective concentration (EC)25s (dry weight) were also similar, at 6.22 and 8.72 microg/L, respectively, but were higher than the pulse-exposure day 10 LOEC and EC25 (dry weight) values of 3.53 and 2.22 microg/L, respectively. Overall, C. tentans was more sensitive to acute and chronic imidacloprid exposure, but less sensitive to a single pulse, than H. azteca. Chronic, low-level exposure to imidacloprid may therefore reduce

  13. Validation of a new standardized test method for the freshwater amphipod Hyalella azteca: Determining the chronic effects of silver in sediment.

    Science.gov (United States)

    Taylor, Lisa N; Novak, Lesley; Rendas, Martina; Antunes, Paula M C; Scroggins, Rick P

    2016-10-01

    Environment Canada has developed a new 42-d sediment toxicity test method that includes a reproduction test endpoint with the freshwater amphipod Hyalella azteca. Because of concerns that existing standard methodologies, whereby adults are transferred to a water-only exposure before release of their first brood at day 28, will lead to internal contaminant depuration and loss of sensitivity, the Environment Canada methodology conducts the entire exposure in sediment. To demonstrate applicability of the method for assessing the toxicity of chemical-spiked sediment, H. azteca were exposed for 42 d to sediment amended with silver nitrate (AgNO3 ). Mortality was significantly higher at the highest sediment concentration of Ag (2088 mg/kg dry wt); however, there was no significant reduction in biomass or reproduction as a result of Ag exposure despite significant bioaccumulation. Based on Ag measurements and speciation modeling, the principle route of Ag exposure was likely through the ingestion of complexed colloidal or particulate Ag. The techniques used to recover young amphipods from sediment were critical, and although this effort can be labor intensive (20-45 min/replicate), the technicians demonstrated 91% recovery in blind trials. For the first time, Environment Canada will require laboratories to report their recovery proficiency for the 42-d test-without this information, data will not be accepted. Overall, the reproduction test will be more applicable when only a few chemical concentrations need to be evaluated in laboratory-amended sediments or for field-collected contaminated site assessments (i.e., contaminated site vs reference site comparisons). Environ Toxicol Chem 2016;35:2430-2438. © 2016 SETAC.

  14. An analysis of lethal and sublethal interactions among type I and type II pyrethroid pesticide mixtures using standard Hyalella azteca water column toxicity tests.

    Science.gov (United States)

    Hoffmann, Krista Callinan; Deanovic, Linda; Werner, Inge; Stillway, Marie; Fong, Stephanie; Teh, Swee

    2016-10-01

    A novel 2-tiered analytical approach was used to characterize and quantify interactions between type I and type II pyrethroids in Hyalella azteca using standardized water column toxicity tests. Bifenthrin, permethrin, cyfluthrin, and lambda-cyhalothrin were tested in all possible binary combinations across 6 experiments. All mixtures were analyzed for 4-d lethality, and 2 of the 6 mixtures (permethrin-bifenthrin and permethrin-cyfluthrin) were tested for subchronic 10-d lethality and sublethal effects on swimming motility and growth. Mixtures were initially analyzed for interactions using regression analyses, and subsequently compared with the additive models of concentration addition and independent action to further characterize mixture responses. Negative interactions (antagonistic) were significant in 2 of the 6 mixtures tested, including cyfluthrin-bifenthrin and cyfluthrin-permethrin, but only on the acute 4-d lethality endpoint. In both cases mixture responses fell between the additive models of concentration addition and independent action. All other mixtures were additive across 4-d lethality, and bifenthrin-permethrin and cyfluthrin-permethrin were also additive in terms of subchronic 10-d lethality and sublethal responses. Environ Toxicol Chem 2016;35:2542-2549. © 2016 SETAC.

  15. Chronic TiO₂ nanoparticle exposure to a benthic organism, Hyalella azteca: impact of solar UV radiation and material surface coatings on toxicity.

    Science.gov (United States)

    Wallis, Lindsay K; Diamond, Stephen A; Ma, Hongbo; Hoff, Dale J; Al-Abed, Souhail R; Li, Shibin

    2014-11-15

    There is limited information on the chronic effects of nanomaterials to benthic organisms, as well as environmental mitigating factors that might influence this toxicity. The present study aimed to fill these data gaps by examining various growth endpoints (weight gain, instantaneous growth rate, and total protein content) for up to a 21 d sediment exposure of TiO2 nanoparticles (nano-TiO2) to a representative benthic species, Hyalella azteca. An uncoated standard, P25, and an Al(OH)3 coated nano-TiO2 used in commercial products were added to sediment at 20 mg/L or 100 mg/L Under test conditions, UV exposure alone was shown to be a greater cause of toxicity than even these high levels of nano-TiO2 exposure, indicating that different hazards need to be addressed in toxicity testing scenarios. In addition, this study showed the effectiveness of a surface coating on the decreased photoactivity of the material, as the addition of an Al(OH)3 coating showed a dramatic decrease in reactive oxygen species (ROS) production. However, this reduced photoactivity was found to be partially restored when the coating had been degraded, leading to the need for future toxicity tests which examine the implications of weathering events on particle surface coatings.

  16. An effects addition model based on bioaccumulation of metals from exposure to mixtures of metals can predict chronic mortality in the aquatic invertebrate Hyalella azteca.

    Science.gov (United States)

    Norwood, Warren P; Borgmann, Uwe; Dixon, D George

    2013-07-01

    Chronic toxicity tests of mixtures of 9 metals and 1 metalloid (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Tl, and Zn) at equitoxic concentrations over an increasing concentration range were conducted with the epibenthic, freshwater amphipod Hyalella azteca. The authors conducted 28-d, water-only tests. The bioaccumulation trends changed for 8 of the elements in exposures to mixtures of the metals compared with individual metal exposures. The bioaccumulation of Co and Tl were affected the most. These changes may be due to interactions between all the metals as well as interactions with waterborne ligands. A metal effects addition model (MEAM) is proposed as a more accurate method to assess the impact of mixtures of metals and to predict chronic mortality. The MEAM uses background-corrected body concentration to predict toxicity. This is important because the chemical characteristics of different waters can greatly alter the bioavailability and bioaccumulation of metals, and interactions among metals for binding at the site of action within the organism can affect body concentration. The MEAM accurately predicted toxicity in exposures to mixtures of metals, and predicted results were within a factor of 1.1 of the observed data, using 24-h depurated body concentrations. The traditional concentration addition model overestimated toxicity by a factor of 2.7.

  17. Re-evaluation of metal bioaccumulation and chronic toxicity in Hyalella azteca using saturation curves and the biotic ligand model

    Energy Technology Data Exchange (ETDEWEB)

    Borgmann, U.; Norwood, W.P.; Dixon, D.G

    2004-10-01

    Bioaccumulation by Hyalella of all metals studied so far in our laboratory was re-evaluated to determine if the data could be explained satisfactorily using saturation models. Saturation kinetics are predicted by the biotic ligand model (BLM), now widely used in modelling acute toxicity, and are a pre-requisite if the BLM is to be applied to chronic toxicity. Saturation models provided a good fit to all the data. Since these are mechanistically based, they provide additional insights into metal accumulation mechanisms not immediately apparent when using allometric models. For example, maximum Cd accumulation is dependent on the hardness of the water to which Hyalella are acclimated. The BLM may need to be modified when applied to chronic toxicity. Use of saturation models for bioaccumulation, however, also necessitates the need for using saturation models for dose-response relationships in order to produce unambiguous estimates of LC50 values based on water and body concentrations. This affects predictions of toxicity at very low metal concentrations and results in lower predicted toxicity of mixtures when many metals are present at low concentrations.

  18. No Evidence for Temporal Variation in a Cryptic Species Community of Freshwater Amphipods of the Hyalella azteca Species Complex

    Directory of Open Access Journals (Sweden)

    Christian Nozais

    2011-08-01

    Full Text Available The co-occurrence of cryptic species of Hyalella amphipods is a challenge to our traditional views of how species assemble. Since these species have similar morphologies, it is not evident that they have developed phenotypic differences that would allow them to occupy different ecological niches. We examined the structure of a community of Hyalella amphipods in the littoral zone of a boreal lake to verify if temporal variation was present in relative abundances. Morphological and molecular analyses using the mitochondrial cytochrome c oxidase I (COI gene enabled us to detect three cryptic species at the study site. No temporal variation was observed in the community, as one cryptic species was always more abundant than the two others. The relative abundances of each species in the community appeared constant at least for the open-water season, both for adult and juvenile amphipods. Niche differences are still to be found among these species, but it is suggested that migration from nearby sites may be an important factor explaining the species co-occurrence.

  19. Sediment contamination of residential streams in the metropolitan Kansas City area, USA: Part II. Whole-sediment toxicity to the amphipod Hyalella azteca.

    Science.gov (United States)

    Tao, J; Ingersoll, C G; Kemble, N E; Dias, J R; Murowchick, J B; Welker, G; Huggins, D

    2010-10-01

    This is the second part of a study that evaluates the influence of nonpoint sources on the sediment quality of five adjacent streams within the metropolitan Kansas City area, central United States. Physical, chemical, and toxicity data (Hyalella azteca 28-day whole-sediment toxicity test) for 29 samples collected in 2003 were used for this evaluation, and the potential causes for the toxic effects were explored. The sediments exhibited a low to moderate toxicity, with five samples identified as toxic to H. azteca. Metals did not likely cause the toxicity based on low concentrations of metals in the pore water and elevated concentrations of acid volatile sulfide in the sediments. Although individual polycyclic aromatic hydrocarbons (PAHs) frequently exceeded effect-based sediment quality guidelines [probable effect concentrations (PECs)], only four of the samples had a PEC quotient (PEC-Q) for total PAHs over 1.0 and only one of these four samples was identified as toxic. For the mean PEC-Q for organochlorine compounds (chlordane, dieldrin, sum DDEs), 4 of the 12 samples with a mean PEC-Q above 1.0 were toxic and 4 of the 8 samples with a mean PEC-Q above 3.0 were toxic. Additionally, four of eight samples were toxic, with a mean PEC-Q above 1.0 based on metals, PAHs, polychlorinated biphenyls (PCBs), and organochlorine pesticides. The increase in the incidence of toxicity with the increase in the mean PEC-Q based on organochlorine pesticides or based on metals, PAHs, PCBs, and organochlorine pesticides suggests that organochlorine pesticides might have contributed to the observed toxicity and that the use of a mean PEC-Q, rather than PEC-Qs for individual compounds, might be more informative in predicting toxic effects. Our study shows that stream sediments subject to predominant nonpoint sources contamination can be toxic and that many factors, including analysis of a full suite of PAHs and pesticides of both past and present urban applications and the origins of

  20. Sediment contamination of residential streams in the metropolitan kansas city area, USA: Part II. whole-sediment toxicity to the amphipod hyalella azteca

    Science.gov (United States)

    Tao, J.; Ingersoll, C.G.; Kemble, N.E.; Dias, J.R.; Murowchick, J.B.; Welker, G.; Huggins, D.

    2010-01-01

    This is the second part of a study that evaluates the influence of nonpoint sources on the sediment quality of five adjacent streams within the metropolitan Kansas City area, central United States. Physical, chemical, and toxicity data (Hyalella azteca 28-day whole-sediment toxicity test) for 29 samples collected in 2003 were used for this evaluation, and the potential causes for the toxic effects were explored. The sediments exhibited a low to moderate toxicity, with five samples identified as toxic to H. azteca. Metals did not likely cause the toxicity based on low concentrations of metals in the pore water and elevated concentrations of acid volatile sulfide in the sediments. Although individual polycyclic aromatic hydrocarbons (PAHs) frequently exceeded effect-based sediment quality guidelines [probable effect concentrations (PECs)], only four of the samples had a PEC quotient (PEC-Q) for total PAHs over 1.0 and only one of these four samples was identified as toxic. For the mean PEC-Q for organochlorine compounds (chlordane, dieldrin, sum DDEs), 4 of the 12 samples with a mean PEC-Q above 1.0 were toxic and 4 of the 8 samples with a mean PEC-Q above 3.0 were toxic. Additionally, four of eight samples were toxic, with a mean PEC-Q above 1.0 based on metals, PAHs, polychlorinated biphenyls (PCBs), and organochlorine pesticides. The increase in the incidence of toxicity with the increase in the mean PEC-Q based on organochlorine pesticides or based on metals, PAHs, PCBs, and organochlorine pesticides suggests that organochlorine pesticides might have contributed to the observed toxicity and that the use of a mean PEC-Q, rather than PEC-Qs for individual compounds, might be more informative in predicting toxic effects. Our study shows that stream sediments subject to predominant nonpoint sources contamination can be toxic and that many factors, including analysis of a full suite of PAHs and pesticides of both past and present urban applications and the origins of

  1. Does long-term fungicide exposure affect the reproductive performance of leaf-shredders? A partial life-cycle study using Hyalella azteca.

    Science.gov (United States)

    Baudy, Patrick; Zubrod, Jochen P; Konschak, Marco; Weil, Mirco; Schulz, Ralf; Bundschuh, Mirco

    2017-03-01

    Leaf-shredding amphipods play a critical role in the ecosystem function of leaf litter breakdown, a key process in many low order streams. Fungicides, however, may adversely influence shredders' behavior and the functions they provide, while there is only limited knowledge concerning effects on their reproductive performance. To assess the latter, a semi-static 56-day partial life-cycle bioassay using the model shredder Hyalella azteca (n = 30) was performed applying two environmentally relevant concentrations of a model fungicide mixture (i.e., 5 and 25 μg/L) composed of five fungicides with different modes of toxic action. Variables related to the food processing (leaf consumption and feces production), growth (body length and dry weight), energy reserves (lipid content), and reproduction (amplexus pairs, number and length of offspring) were determined to understand potential implications in the organisms' energy budget. While the fungicides did not affect leaf consumption, both fungicide treatments significantly reduced amphipods' feces production (∼20%) compared to the control. This observation suggests an increased food utilization to counteract the elevated and stress-related energy demand: although growth as well as energy reserves were unaffected, amplexus pairs were less frequently observed in both fungicide treatments (∼50-100%) suggesting a tradeoff regarding energy allocation favoring the maintenance of fundamental functions at the organism level over reproduction. As a result, the time to release of first offspring was delayed in both fungicide treatments (7 and 14 days) and the median number of offspring was significantly lower in the 25-μg/L treatment (100%), whereas offspring length remained unaffected. The results of this study thus indicate that chronic fungicide exposures can negatively impact shredders' reproductive performance. This may translate into lower abundances and thus a reduced contribution to leaf litter breakdown in

  2. 酸损害湖泊中底栖无脊椎动物(Stenacron interpunctatum,Stenonema femoratum和Hyalella azteca)的再集群现象%Recolonization of Acid-damaged Lakes by the Benthic Invertebrates Stenacron interpunctatum, Stenonema femoratum and Hyalella azteca

    Institute of Scientific and Technical Information of China (English)

    Ed Snucins

    2003-01-01

    本文描述了加拿大基拉尼公园里的酸损害湖中3种底栖无脊椎动物的再集群现象:它们是两种蜉蝣类动物(Stenonema femoratum,Stenacron interpunctatum)和一种端足类甲壳动物(Hyalella azteca)。1995-1997年间对119个湖的端足类甲壳动物以及77个湖的蜉蝣类动物进行了概要调查,同时确定Stenonema femoratum和Hyalella azteca的pH临界值是5.6。而Stenacron interpunctatum的pH临界值是5.3。从1997-2002年,通过对2个酸损害湖和2个参考湖深入研究。在能够估计出出现时间的地方,种的pH阈值达到后不到4-8年。就可以重建Stenacron interpunctatum,Stenonema femoratum和Hyalella azteca。在最小的湖(11hm2)中监测到集群现象之后3年。该湖内Stenacron interpunctatum到所有栖息地的扩散完成。可以预测,Stenacron interpunctatum在最大的湖(189hm2)内的扩散需要更长的时间。从估算的pH值恢复到湖内蜉蝣类动物重建,再到其后扩散到所有适合栖息地的时间滞后为11-22年之久或更长。虽然在恢复湖中Stenacron interpunctatum的密度增加到高于参考湖的水平。但在6年期间的监测中尚未达到稳定的终点。

  3. Redescription of the freshwater amphipod Hyalella faxoni from Costa Rica (Crustacea: Amphipoda: Hyalellidae

    Directory of Open Access Journals (Sweden)

    Exequiel R. González

    2002-06-01

    Full Text Available Hyalella faxoni Stebbing, 1903 from Costa Rica is redescribed. The species was previously in the synonymy of Hyalella azteca (Saussure, 1858. The morphological differences between these two species are discussedLa especie Hyalella faxoni Stebbing, 1903 de Costa Rica es redescrita. Esta especie estaba previamente en la sinonimia de Hyalella azteca (Saussure, 1858. Se discuten en este trabajo las diferencias morfológicas entre las dos especies

  4. Relative contribution of food and water to 27 metals and metalloids accumulated by caged Hyalella azteca in two rivers affected by metal mining

    Energy Technology Data Exchange (ETDEWEB)

    Borgmann, U. [Water Science and Technology Directorate, Environment Canada, 867 Lakeshore Road, Burlington, ON, L7R 4A6 (Canada)]. E-mail: uwe.borgmann@ec.gc.ca; Couillard, Y. [Existing Substances Division, Environment Canada, 351 Saint-Joseph Boulevard, Gatineau, QC, K1A 0H3 (Canada); Grapentine, L.C. [Water Science and Technology Directorate, Environment Canada, 867 Lakeshore Road, Burlington, ON, L7R 4A6 (Canada)

    2007-02-15

    Hyalella were caged at three sites in each of the two rivers for 17 days. Food added to the cages consisted of plant and detrital material collected from the same, or other, sites. Concentrations of some metals in Hyalella (e.g., Cd and Cu), but not others (e.g., Se), appeared to reach steady-state within 5 days in one of the rivers. Metal accumulation was minimal by day 5 in the other river, possibly due to the very low temperatures in this river for the first part of the exposure period. Both analysis of variance and analysis of covariance, using site as a categorical variable and metal in food as either a categorical or continuous variable, indicated that Cd, Cu and Se were the only metals for which concentration in food had a significant effect on concentration in Hyalella. Nevertheless, water was still a major source for these metals as well. Other metals which varied by over fivefold in food but for which concentration in food had no effect on concentration in Hyalella included Ag, As, Bi, Sb, U and Zn. Concentrations of the remaining metals varied less than fourfold in food, making it difficult to determine if these were accumulated from food. - Cadmium, copper and selenium were the only metals in food that correlated with increased body concentrations of metals in Hyalella, but even these metals were accumulated largely from water.

  5. Relative sensitivity of an amphipod Hyalella azteca, a midge Chironomus dilutus, and a unionid mussel Lampsilis siliquoidea to a toxic sediment.

    Science.gov (United States)

    Ingersoll, Chris G; Kunz, James L; Hughes, Jamie P; Wang, Ning; Ireland, D Scott; Mount, David R; Hockett, J Russell; Valenti, Theodore W

    2015-05-01

    The objective of the present study was to evaluate the relative sensitivity of test organisms in exposures to dilutions of a highly toxic sediment contaminated with metals and organic compounds. One dilution series was prepared using control sand (low total organic carbon [TOC; azteca; 10-d and 28-d exposures), a midge (Chironomus dilutus; 20-d and 48-d exposures started with azteca were more sensitive endpoints in 28-d exposures than in 10-d exposures. Weight and biomass of L. siliquoidea were sensitive endpoints in both sand and West Bearskin Lake sediment dilutions. Metals, ammonia, oil, and other organic contaminants may have contributed to the observed toxicity.

  6. SENSITIVITY DIFFERENCE AMONG VARIOUS STRAINS OF HYALLELA AZTECA

    Science.gov (United States)

    The North American amphipod Hyalella azteca is widely used in toxicity testing. H. azteca has a broad geographic distribution, and genetic evidence suggests that populations diverged from each other long ago. The importance of this genetic divergence to toxicity testing is uncle...

  7. SENSITIVITY DIFFERENCE AMONG VARIOUS STRAINS OF HYALLELA AZTECA

    Science.gov (United States)

    The North American amphipod Hyalella azteca is widely used in toxicity testing. H. azteca has a broad geographic distribution, and genetic evidence suggests that populations diverged from each other long ago. The importance of this genetic divergence to toxicity testing is uncle...

  8. Evaluation of toxicity to the amphipod, Hyalella azteca, and to the midge, Chironomus dilutus; and bioaccumulation by the oligochaete, Lumbriculus variegatus, with exposure to PCB-contaminated sediments from Anniston, Alabama

    Science.gov (United States)

    Ingersoll, Christopher G.; Steevens, Jeffery A.; MacDonald, Donald D.; Brumbaugh, William G.; Coady, Matthew R.; Farrar, J. Daniel; Lotufo, Guilherme R.; Kemble, Nile E.; Kunz, James L.; Stanley, Jacob K.; Sinclair, Jesse A.; Ingersoll, Christopher G.; Steevens, Jeffery A.; MacDonald, Donald D.

    2014-01-01

    The U.S. Environmental Protection Agency (USEPA) requested that as part of the remedial investigation for the Anniston, Alabama Polychlorinated Biphenyl (PCB) Site (Anniston PCB Site), that Pharmacia Corporation and Solutia Inc. (P/S) perform long-term reproduction toxicity tests with the amphipod, Hyalella azteca, and the midge, Chironomus dilutus, and bioaccumulation tests with the oligochaete, Lumbriculus variegatus, using sediment samples collected from reference locations and from Operable Unit 4 of the Anniston PCB Site. The sediment toxicity testing and sediment bioaccumulation results will be used by ARCADIS U.S., Inc. (ARCADIS) as part of a weight-of-evidence assessment to evaluate risks and establish sediment remediation goals for contaminants to sediment-dwelling organisms inhabiting the Anniston PCB Site. The goal of this study was to characterize relations between sediment chemistry and sediment toxicity and relations between sediment chemistry and sediment bioaccumulation in samples of sediments collected from the Anniston PCB Site. A total of 32 samples were evaluated from six test sites and one reference site to provide a wide range in concentrations of chemicals of potential concern (COPCs) including PCBs in samples of whole sediment. The goal of this study was not to determine the extent of sediment contamination across the Anniston PCB Site. Hence, the test sites or samples collected from within a test site were not selected to represent the spatial extent of sediment contamination across the Anniston PCB Site. Sediment chemistry, pore-water chemistry, and sediment toxicity data were generated for 26 sediment samples from the Anniston PCB Site. All of the samples were evaluated to determine if they qualified as reference sediment samples. Those samples that met the chemical selection criteria and biological selection criteria were identified as reference samples and used to develop the reference envelope for each toxicity test endpoint. Physical

  9. Simultaneous determination of the Cd and Zn total body burden of individual, nearly microscopic, nanoliter-volume aquatic organisms (Hyalella azteca) by rhenium-cup in-torch vaporization (ITV) sample introduction and axially viewed ICP-AES

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Andrea T.; Badiei, Hamid R.; Karanassios, Vassili [University of Waterloo, Department of Chemistry, Waterloo, ON (Canada); Evans, J. Catherine [University of Waterloo, Department of Biology, Waterloo, ON (Canada)

    2004-09-01

    The Cd and Zn total body burden of individual, up to 7-day-old aquatic organisms (Hyalella aztecabenthic amphipod) with an average volume of approximately 100 nL was determined simultaneously by using rhenium-cup (Re-cup) in-torch vaporization (ITV) sample introduction and an axially viewed inductively coupled plasma atomic emission spectrometry (ICP-AES) system. The direct elemental analysis capabilities of this system (i.e., no sample digestion) reduced sample preparation time, eliminated contamination concerns from the digestion reagent and, owing to its detection limits (e.g., in the low pg range for Cd and Zn), vit enabled simultaneous determinations of Cd and Zn in individual, neonate and young juvenile specimens barely visible to the unaided eye (e.g., nearly microscopic). As for calibration, liquid standards and the standard additions method were tested. Both methods gave comparable results, thus indicating that in this case liquid standards can be employed for calibration, and in the process making use of the standard additions method unnecessary. Overall, the ITV-ICP-AES approach by-passed the time-consuming acid digestions, eliminated the potential for contamination from the digestion reagents, improved considerably the speed of acquisition of analytical information and enabled simultaneous determinations of two elements using individual biological specimens. (orig.)

  10. Water Quality And Sediment Evaluation for Inner Harbor Navigation Canal Lock Replacement Project, New Orleans, Louisiana

    Science.gov (United States)

    2011-08-01

    118 Figure 29. Hyalella azteca 10-day freshwater solid phase toxicity tests. .......................................... 123 Figure 30. Benthic...toxicity evaluation. Mean percent survival of Hyalella azteca exposed to IHNC dredged material...121 Table 40. Hyalella azteca 10-day freshwater solid phase toxicity tests

  11. Preparation and characterization of a hetero functional system of gold nanoparticles labeled with {sup 99m}Tc and conjugated to the sequence Arg-Gly-Asp for detection in vivo of angio genesis and evaluation of their toxicity in Hyalella aztec; Preparacion y caracterizacion de un sistema heterofuncional de nanoparticulas de oro marcadas con Tecnecio-99m y conjugadas a la secuencia Arg-Gly-Asp para la deteccion in vivo de angiogenesis y la evaluacion de su toxicidad en Hyalella azteca

    Energy Technology Data Exchange (ETDEWEB)

    Morales A, E.

    2012-07-01

    spectroscopy techniques demonstrated that AuNP were functionalized with peptides. Rp was 96 {+-} 2% without post-labeling purification. {sup 99m}Tc-HYNIC-G GC-AuNP-RGD showed specific recognition for {alpha}{sub v}{beta}{sub 3} integrin s expressed in C6 cells, and 3 h after i.p. administration in mice, the tumor uptake was 8.18 {+-} 0.57% Id/g. Micro-SPECT/CT images showed evident tumor uptake. {sup 99m}Tc-HYNIC-G GC-AuNP-RGD demonstrates properties suitable for use as a new target-specific agent for molecular imaging of tumor {alpha}{sub v}{beta}{sub 3} expression. the second aim of this research was to determine the eco toxicological risk, measured by oxidative stress induction in Hyalella aztec, of the well-characterized multifunctional RGD-AuNP system (Tc-HYNIC-G GC-AuNP-c[RGDfK(C)]). In acute toxicological studies, a median lethal concentration of 1.83 cm{sup 2} per milliliter of medium was established for the Tc-HYNIC-G GC-AuNP-c[RGDfK(C)] conjugate. Tests assessing the effects of oxidative stress such as lipo peroxidation and protein carbonyl protein content suggest that this nano conjugate does not induces changes in oxidative markers because the activity of antioxidant defenses including catalase, glutathione peroxidase and superoxide dismutase do not show an increase related to oxidative stress imbalance. Due to the chain length and steric effect of the peptides attached to gold nanoparticles by Au-S bonds, the Tc-HYNIC-G GC-AuNP-C[RGDfK(C)] complex does not react with intracellular glutathione or thiol-proteins and, therefore, does not induce increases in reactive oxygen species. Therefore, Tc-HYNIC-G GC-AuNP-c[RGDfK(C)] (20 nm) is a new chemically stable diagnostic pharmaceutical that does not induce eco toxicity measured by the oxidative stress induction in Hyalella aztec after complete radionuclide decay. This study suggests that Hyalella aztec is a suitable model animal for environmental toxicology studies of nanoparticles. (Author)

  12. Release of Metal Impurities from Carbon Nanomaterials Influences Aquatic Toxicity

    Science.gov (United States)

    2009-01-01

    in commerce. A 10 day sediment toxicity test for survival and growth of the freshwater amphipod, Hyalella azteca , exposed to sediments amended with a...reporting on the prepared leachate water quality (Table S1), solid phase soot contaminants (Table S2), Hyalella azteca toxicity data (Table S3

  13. Toxicity of stormwater treatment pond sediments to Hyallela azteca (Amphipoda)

    Science.gov (United States)

    Karouna-Renier, N.K.; Sparling, D.W.

    1997-01-01

    Stormwater wetlands are created to contain runoff from human developments and are designed to retain contaminants such as heavy metals, petroleum hydrocarbons, silt, pesticides, and nutrients before the runoff enter natural waterways. Because of this design, stormwater wetlands have a potential of becoming toxic sinks to organisms utilizing the wetlands for habitat. We conducted a 10-day sediment bioassay on Hyallela azteca as part of a larger study on the possible hazards of stormwater wetlands to aquatic invertebrates. Water and sediments from 10 wetlands separated into reference, residential, commercial, and highway land uses were used. No differences in survival were observed among land use categories, possibly because the ratio of acid volatile sulfides/simultaneously extractable metals (AVS/SEM) was > 1.0 for all of the ponds tested; values > 1 in this ratio are indications that toxic metals may not be bioavailable. Survival and growth rates correlated positively with AVS.

  14. Effects of calcium, magnesium, and sodium on alleviating cadmium toxicity to Hyalella azteca

    Science.gov (United States)

    Jackson, B.P.; Lasier, P.J.; Miller, W.P.; Winger, P.V.

    2000-01-01

    Toxicity of trace metal ions to aquatic organisms, arising through either anthropogenic inputs or acidification of surface waters, continues to be both a regulatory and environmental problem. It is generally accepted that the free metal ion is the major toxic species (Florence et a1.,1992) and that inorganic or organic complexation renders the metal ion non-bioavailable (Meador, 1991, Galvez and Wood, 1997). However, water chemistry parameters such as alkalinity, hardness, dissolved organic carbon and pH influence metal ion toxicity either directly by lowering free metal ion concentration or indirectly through synergistic or antagonistic effects. Alkalinity and salinity can affect the speciation of metal ions by increasing ion-pair formation, thus decreasing free metal ion concentration. For example, Cu was found to be less toxic to rainbow trout in waters of high alkalinity (Miller and Mackay, 1980), due to formation of CuCO3 ion pair, and corresponding reduction in free Cu2+ concentration. The influence of salinity on the toxicity of cadmium to various organisms has been demonstrated in a number of studies (Bervoets et al., 1995, Hall et al., 1995, Lin and Dunson, 1993, Blust et al., 1992). In all these studies the apparent toxicity of cadmium was lowered as salinity was increased due to increased formation of CdC1+ and CDCl2 aqueous complexes that are non-toxic or of much lower toxicity than the free Cd2+ ion. Changes in pH exert both a biological and chemical effect on metal ion toxicity (Campbell and Stokes, 1985). Low pH favors greater metal ion solubility, and, in the absence of complexing ions, reduced speciation of the metal ion, which tends to increase toxicity compared to higher pH. However, Iow pH also enhances competition between H+ and metal ion for cell surface binding sites, which tends to decrease metal ion toxicity.

  15. BIOAVAILABILITY OF MERCURY IN SEDIMENTS FROM A FLOOD CONTROL RESERVOIR TO HYALELLA AZTECA

    Science.gov (United States)

    In the last three years, mercury contamination in North Mississippi flood control reservoirs has become a growing concern. Previous data indicate that three flood control reservoirs have similar total mercury sediment concentrations and that fish collected from one reservoir cont...

  16. Sediment quality assessment of Beasley Lake: Bioaccumulation and effects of pesticides in Hyalella azteca

    Science.gov (United States)

    Beasley Lake is a Conservation Evaluation Assessment Program (CEAP) watershed in the intensively cultivated Mississippi Delta, USA. Lake sediment quality at three sites was evaluated in 2004 and 2008 for biological impairment and uptake (viz. body residues) from 14 pesticides and three metabolites ...

  17. BIOAVAILABILITY OF MERCURY IN SEDIMENTS FROM A FLOOD CONTROL RESERVOIR TO HYALELLA AZTECA

    Science.gov (United States)

    In the last three years, mercury contamination in North Mississippi flood control reservoirs has become a growing concern. Previous data indicate that three flood control reservoirs have similar total mercury sediment concentrations and that fish collected from one reservoir cont...

  18. Acute toxicity of fire-retardant and foam-suppressant chemicals to yalella azteca (Saussure)

    Science.gov (United States)

    McDonald, Susan F.; Hamilton, Steven J.; Buhl, Kevin J.; Heisinger, James F.

    1997-01-01

    Acute toxicity tests were conducted with Hyalella azteca Saussure (an amphipod) exposed in soft and hard waters to three fire retardants (Fire-Trol GTS-R, Fire-Trol LCG-R, and Phos-Chek D75-F) and two foam suppressants (Phos-Chek WD-881 and Silv-Ex). The chemicals were slightly to moderately toxic to amphipods. The most toxic chemical to amphipods in soft and hard water was Phos-Chek WD-881 (96-h mean lethal concentration [LC50] equal to 10 mg/L and 22 mg/L, respectively), and the least toxic chemical to amphipods in soft water was Fire-Trol GTS-R (96-h LC50 equal to 127 mg/L) and in hard water was Fire-Trol LCG-R (96-h LC50 equal to 535 mg/L). Concentrations of ammonia in tests with the three fire retardants and both water types were greater than reported LC50 values and probably were the major toxic component. Estimated un-ionized ammonia concentrations near the LC50 were frequently less than the reported LC50 ammonia concentrations for amphipods. The three fire retardants were more toxic in soft water than in hard water even though ammonia and un-ionized ammonia concentrations were higher in hard water tests than in soft water tests. The accidental entry of fire-fighting chemicals into aquatic environments could adversely affect aquatic invertebrates, thereby disrupting ecosystem function.

  19. Seamless Hourly Rainfall Ensemble Forecasts for 0 - 10 days

    Science.gov (United States)

    Cooper, Shaun; Seed, Alan

    2014-05-01

    The Australian Bureau of Meteorology uses a number of Numerical Weather Prediction (NWP) models to generate deterministic rainfall forecasts over a range of lead-times, each with a different resolution in space and time and with different forecast domains. High resolution regional NWP models are used to generate forecasts for the first three days, and are typically more accurate than lower resolution Global NWP models that produce forecasts for longer lead times. Consequently, there is a requirement for a seamless forecast system that is able to blend the various NWP forecasts into a single forecast with a uniform resolution over the entire forecast period. NWP rainfall forecasts contain errors at scales that are significant for even large river basins, and ensemble hydrological prediction systems require ensembles of the order of 100 members, which is well beyond the size that can be generated by NWP ensemble systems. The idea, therefore, is to blend the NWP models in such a way that recognises the skill of the NWP at a particular scale and lead time and to use a stochastic model of forecast errors to perturb the blended deterministic forecast to generate a large ensemble. NWP uncertainties are scale and forecast lead time dependent, especially at long forecast lead times, and are characteristic to each model. By blending the models scale by scale it is possible to recognise the increased skill of the models at larger spatial scales and shorter lead times. The stochastic model is applied at each scale, adding increasingly more variability at smaller spatial scales, while preserving the space-time structure of rain. This process allows an ensemble to be generated by blending deterministic forecasts. Two NWP models from the Bureau, ACCESS-G (Global) (~40 km by ~40 km, 3 hourly out to 10 days) and ACCESS-R (Regional) (~12 km by ~12 km, 1 hourly out to 3 days), are downscaled and blended with the stochastic model to produce an ensemble of hourly forecasts out to 10

  20. Reconstructive valve surgery within 10 days of stroke in endocarditis.

    Science.gov (United States)

    Raman, Jai; Ballal, Apoorva; Hota, Bala; Mirza, Sara; Lai, David; Bleck, Thomas; Lateef, Omar

    2016-07-01

    The optimal timing of surgical treatment for infective endocarditis complicated by cerebrovascular events is controversial, largely due to the perceived risk of perioperative intracranial bleeding. Current guidelines suggest waiting 2 weeks between the diagnosis of stroke and surgery. The aim of this study was to investigate the clinical and neurological outcomes of early surgery following a stroke. This was a single-center retrospective analysis of 12 consecutive patients requiring surgery for infective endocarditis between 2011 and 2014 at Rush University Medical Center, with either ischemic (n = 6) and/or hemorrhagic (n = 6) cerebrovascular complications. All underwent computed tomographic angiography prior to early valve reconstructive surgery to identify potentially actionable neurological findings. Early valve surgery was performed for ongoing sepsis or persistent emboli. Neurologic risk and outcome were assessed pre- and postoperatively using the National Institutes of Health Stroke Scale and the Glasgow Outcome Scale, respectively. All 12 patients underwent surgical treatment within 10 days of the diagnosis of stroke. Mortality in the immediate postoperative period was 8%. Eleven of the 12 patients exhibited good neurological recovery in the immediate postoperative period, with a Glasgow Outcome Scale score ≥ 3. There was no correlation between duration of cardiopulmonary bypass and neurological outcomes. Early cardiac surgery in patients with infective endocarditis and stroke maybe lifesaving with a low neurological risk. Comprehensive neurovascular imaging may help in identifying patient-related risk factors. © The Author(s) 2016.

  1. Normal height and weight in a series of ambulant Duchenne muscular dystrophy patients using the 10 day on/10 day off prednisone regimen.

    NARCIS (Netherlands)

    Dam, K. ten; Groot, I.J.M. de; Noordam, C.; Alfen, N. van; Hendriks, J.C.M.; Sie, L.T.L.

    2012-01-01

    Prednisone treatment delays the progressive course of Duchenne muscular dystrophy. The aim of this study was to determine the influence of the 10 day on/10 day off treatment on height and weight. We retrospectively reviewed the growth and weight charts of Duchenne patients born between 1988 and 2006

  2. Analyse de Viaje al pasado: los aztecas

    Directory of Open Access Journals (Sweden)

    Denis Lucchinacci

    2005-11-01

    Full Text Available 1. Présentation du logiciel Viaje al pasado: los aztecas (el perfecto simple y el imperfecto en la narración y la descripción a été conçu par Annie Desnoyers, linguiste à l'université de Montréal et Matilde Asencio, enseignante au Cégep du Vieux Montréal (Collège d'enseignement général et professionnel [], pour un public d'étudiants d'Espagnol Langue Étrangère (ELE. Disponible en deux versions - en ligne et sous forme de cédérom -, il s'agit d'un exerciseur destiné à la pratique du passé e...

  3. Analyse de Viaje al pasado: los aztecas

    OpenAIRE

    Denis Lucchinacci

    2005-01-01

    1. Présentation du logiciel Viaje al pasado: los aztecas (el perfecto simple y el imperfecto en la narración y la descripción) a été conçu par Annie Desnoyers, linguiste à l'université de Montréal et Matilde Asencio, enseignante au Cégep du Vieux Montréal (Collège d'enseignement général et professionnel []), pour un public d'étudiants d'Espagnol Langue Étrangère (ELE). Disponible en deux versions - en ligne et sous forme de cédérom -, il s'agit d'un exerciseur destiné à la pratique du passé e...

  4. Interlaboratory Evaluation of Hyalella Azteca and Chironomus Tentans Short-term and Long-term Sediment Toxicity Tests

    Science.gov (United States)

    This paper presents the results of interlaboratory toxicity tests on sediment toxicity methods for use in routine testing and this data has been presented in an EPA report and this is a summary of that data.

  5. The Influence of Test Conditions on the Performance of Chironomus dilutus and Hyalella azteca in Sediment Toxicity Tests

    Science.gov (United States)

    In most all sediment toxicity assessments, the performance of organisms in control sediments is a key parameter in defining sediment toxicity, whether through direct statistical comparison to control or by normalizing to control performance to compare results across sites or batc...

  6. The acute and chronic toxicity of major geochemical ions to Hyalella azteca Ion interactions and comparisons to other species

    Science.gov (United States)

    We have previously reported that the acute and chronic toxicities of major geochemical ions (Na, K, Ca, Mg, Cl, SO4, HCO3) to Ceriodaphnia dubia can involve multiple, independent mechanisms. The toxicities of K, Mg, and Ca salts were best related to the chemical activity of the c...

  7. Responses of Hyalella azteca to a Pesticide-Nutrient Mixture in Vegetated and Non-vegetated Wetland Mesocosms

    Science.gov (United States)

    Aquatic vegetation has been shown to improve water quality by trapping and processing contaminants such as pesticides, nutrients and sediments. Currently there is little information regarding effects of pesticide and nutrient mixtures on aquatic biota in these systems and the influence aquatic vege...

  8. The acute and chronic toxicity of major geochemical ions to Hyalella azteca Ion interactions and comparisons to other species

    Science.gov (United States)

    We have previously reported that the acute and chronic toxicities of major geochemical ions (Na, K, Ca, Mg, Cl, SO4, HCO3) to Ceriodaphnia dubia can involve multiple, independent mechanisms. The toxicities of K, Mg, and Ca salts were best related to the chemical activity of the c...

  9. The Influence of Test Conditions on the Performance of Chironomus dilutus and Hyalella azteca in Sediment Toxicity Tests

    Science.gov (United States)

    In most all sediment toxicity assessments, the performance of organisms in control sediments is a key parameter in defining sediment toxicity, whether through direct statistical comparison to control or by normalizing to control performance to compare results across sites or batc...

  10. Interlaboratory Evaluation of Hyalella Azteca and Chironomus Tentans Short-term and Long-term Sediment Toxicity Tests

    Science.gov (United States)

    This paper presents the results of interlaboratory toxicity tests on sediment toxicity methods for use in routine testing and this data has been presented in an EPA report and this is a summary of that data.

  11. Revernacularizing Classical Nahuatl through Danza (Dance) Azteca-Chichimeca.

    Science.gov (United States)

    Tezozomoc

    Traditional Danza Azteca-Chichimeca (an indigenous dance society) contains the elements required for the intergenerational revernacularization of an indigenous language, in this case classical Nahuatl. These requirements entail creating an intergenerational environment in which participants can gain prestige, friendship, and affection and can…

  12. 78 FR 69703 - 10-Day Notice of Proposed Information Collection: Generic Customer Satisfaction Surveys; Physical...

    Science.gov (United States)

    2013-11-20

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT 10-Day Notice of Proposed Information Collection: Generic Customer Satisfaction... Customer Satisfaction Surveys Physical Inspection Alignment Pilot Program--Expansion Announcement....

  13. A new species of Hyalella (Crustacea, Amphipoda, Dogielinotidae) from the Atlantic Forest of Misiones, Argentina

    Science.gov (United States)

    Colla, María Florencia; César, Inés Irma

    2015-01-01

    Abstract The freshwater genus Hyalella Smith, 1874 has a distribution restricted to the Western Hemisphere with most species being found in South America. In this report we describe a new species of Hyalella from the Atlantic Forest of the Misiones province, Argentina. PMID:25685030

  14. A new species of Hyalella (Crustacea, Amphipoda, Dogielinotidae) from the Atlantic Forest of Misiones, Argentina.

    Science.gov (United States)

    Colla, María Florencia; César, Inés Irma

    2015-01-01

    The freshwater genus Hyalella Smith, 1874 has a distribution restricted to the Western Hemisphere with most species being found in South America. In this report we describe a new species of Hyalella from the Atlantic Forest of the Misiones province, Argentina.

  15. Pseudacteon Parasitoids of Azteca instabilis Ants in Southern Mexico (Diptera: Phoridae; Hymenoptera: Formicidae

    Directory of Open Access Journals (Sweden)

    Brian V. Brown

    2012-01-01

    Full Text Available Three new species of the genus Pseudacteon are described, all from Chiapas, Mexico, and all of which are parasitoids of the ant Azteca instabilis. Sternite 6 of Pseudacteon dorymyrmecis Borgmeier is illustrated for the first time, and P. confusus Disney is synonymized with this species. The natural history of the Azteca-Pseudacteon interaction is described.

  16. Suspected transient pseudohypoaldosteronism in a 10-day-old quarter horse foal

    OpenAIRE

    Arroyo, Luis G.; Vengust, Modest; Dobson, Howard; Viel, Laurent

    2008-01-01

    A 10-day-old quarter horse colt was presented for signs of disorientation and inability to nurse. Hydronephrosis/hydroureters, with concomitant pyelonephritis and a severe electrolytes disturbance, were diagnosed. The clinical findings closely resembled those described for a syndrome of transient pseudohypoaldosteronism in human neonates.

  17. Suspected transient pseudohypoaldosteronism in a 10-day-old quarter horse foal.

    Science.gov (United States)

    Arroyo, Luis G; Vengust, Modest; Dobson, Howard; Viel, Laurent

    2008-05-01

    A 10-day-old quarter horse colt was presented for signs of disorientation and inability to nurse. Hydronephrosis/hydroureters, with concomitant pyelonephritis and a severe electrolytes disturbance, were diagnosed. The clinical findings closely resembled those described for a syndrome of transient pseudohypoaldosteronism in human neonates.

  18. A new species of freshwater amphipod (Dogielinotidae, Hyalella from Southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Rafaela Bastos-Pereira

    Full Text Available To the present 57 species of Hyalella were described for Americas, 15 of them found in Brazil, which is among the most diverse countries for this genus. This work aims to describe a new Hyalella species with benthic habits which is found in a water source on Southeastern Brazil. It is mainly characterized by a wide truncated process formed near the dactylus insertion on gnathopod 2, besides both coxal and sternall gills present on pereonits 2 to 7. This work improves the knowledge on biodiversity about Hyalella species.

  19. Climate Prediction Center (CPC) 6 to 10 Day Probabilistic Precipitation Outlook for the Contiguous United States and Alaska

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Climate Prediction Center (CPC) issues 6 to 10 day probabilistic precipitation outlooks for the United States. The 6-10 day Outlook gives the confidence that a...

  20. Climate Prediction Center (CPC) 6 to 10 Day Probabilistic Temperature Outlook for the Contiguous United States and Alaska

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Climate Prediction Center (CPC) issues 6 to 10 day probabilistic temperature outlooks for the United States. The 6-10 day Outlook gives the confidence that a...

  1. Effects of prostaglandin administration 10 days apart on reproductive parameters of cyclic dairy nulliparous goats

    Directory of Open Access Journals (Sweden)

    J.F. Fonseca

    2012-04-01

    Full Text Available This study reported the effects of prostaglandin (PGF2a administration 10 days apart on reproductive parameters of cyclic artificial inseminated (AI nulliparous Alpine (n=9 and Saanen (n=9 goats. Animals received two doses of 22.5mg PGF2a 10 days apart. After 1st and 2nd PGF2a administrations, estrus was monitored at 12 h intervals, with a buck teaser. Plasma progesterone concentration (ng/mL was determined from blood sampled on day 0 (1st PGF2a and the following 5, 10 (2nd PGF2a, 15, 20, 25 and 30 days. After the onset of the second estrus, females were transrectally (5 MHz probe scanned at 4 hour intervals until at least 8h after ovulation. Pregnancy was checked through transrectal ultrasound on days 20, 25, 30, 35 and 90 after insemination. All parameters studied did not differ between breeds (P>0.05. Estrous response and interval to estrus, respectively, after 1st (78.9% and 50.6±17.2h and 2nd PGF2a (88.9% and 50.0±14.8h administration did not differ (P>0.05. Overall animals ovulating (100.0%, interval to ovulation after 2nd PGF2a (64.5±19.5h and after estrous onset (18.0±9.1h, ovulation rate (1.3±0.5, diameter of ovulatory follicle (8.1±1.1mm were recorded. Embryo loss occurred before day 30 of pregnancy. Estrus can be efficiently synchronized in nulliparous Alpine and Saanen goats with two doses of prostaglandin 10 days apart.

  2. Sequential changes of body composition in patients with enterocutaneous fistula during the 10 days after admission

    Institute of Scientific and Technical Information of China (English)

    Xin-Bo Wang; Jian-An Ren; Jie-Shou Li

    2002-01-01

    AIM: To investigate the sequential changes of body composition in the metabolic response that occurred in a group of patients with enterocutaneous fistula after admission to the hospital.METHODS: Sixty-one patients with enterocutaneous fistula admitted to our hospital had measurements of body composition by multiple-frequency bioelectrical impedance analysis after admission and 5, 10 days later. Sequential measurements of plasma constitutive proteins were also made. RESULTS: The body weight, fat-free mass, body mass index, and body cell mass were initially well below the normal range, especially the body mass index and body cell mass. And all the data gradually moved up over the 10-day study period, only a highly significant difference was found in body cell mass. Once the patients Received nutrition supplement, ECW began to return to normal range slowly as well as ICW and TBW began to rise up, and ECW/TBW significantly declined to near normal level by day 10 in either male or female patients. There was a reprioritization of plasma constitutive protein synthesis that was obligatory and independent of changes in FFM.CONCLUSION: Serial measurements can quantify the disturbance of body composition in enterocutaneous fistula patients. The early nutritional intervention rapidly ameliorates the abnormal distribution of body water while the state-of-the-art surgical management prevents the further deterioration in cellular composition.

  3. Tensiones entre el esencialismo azteca y el universalismo New Age a partir del estudio de las danzas “conchero-aztecas

    OpenAIRE

    Torre, Renée de la

    2009-01-01

    El propósito del trabajo es describir y analizar comparativamente dos expresiones contemporáneas de la religiosidad mexhica que se manifiestan en los grupos de danza conocidos como concheros o aztecas. La primera es la versión mexicanista, que se opone al sincretismo con la religión católica y la cultura occidental y que plantea la esencialización de lo “auténticamente” azteca promoviendo la restauración del Anáhuac en el presente; la segunda es una versión sincrética, conocida como neomexica...

  4. WASP-117b: a 10-day-period Saturn in an eccentric and misaligned orbit

    Science.gov (United States)

    Lendl, M.; Triaud, A. H. M. J.; Anderson, D. R.; Collier Cameron, A.; Delrez, L.; Doyle, A. P.; Gillon, M.; Hellier, C.; Jehin, E.; Maxted, P. F. L.; Neveu-VanMalle, M.; Pepe, F.; Pollacco, D.; Queloz, D.; Ségransan, D.; Smalley, B.; Smith, A. M. S.; Udry, S.; Van Grootel, V.; West, R. G.

    2014-08-01

    We report the discovery of WASP-117b, the first planet with a period beyond 10 days found by the WASP survey. The planet has a mass of Mp = 0.2755 ± 0.0089 MJ, a radius of Rp= 1.021_{-0.065+0.076 Rjup} and is in an eccentric (e = 0.302 ± 0.023), 10.02165 ± 0.00055 d orbit around a main-sequence F9 star. The host star's brightness (V = 10.15 mag) makes WASP-117 a good target for follow-up observations, and with a periastron planetary equilibrium temperature of Teq= 1225_{-39+36} K and a low planetary mean density (ρp= 0.259_{-0.048+0.054 ρjup}) it is one of the best targets for transmission spectroscopy among planets with periods around 10 days. From a measurement of the Rossiter-McLaughlin effect, we infer a projected angle between the planetary orbit and stellar spin axes of β = -44 ± 11 deg, and we further derive an orbital obliquity of ψ = 69.6 +4.7-4.1 deg. Owing to the large orbital separation, tidal forces causing orbital circularization and realignment of the planetary orbit with the stellar plane are weak, having had little impact on the planetary orbit over the system lifetime. WASP-117b joins a small sample of transiting giant planets with well characterized orbits at periods above 8 days. Based on data obtained with WASP-South, CORALIE and EulerCam at the Euler-Swiss telescope, TRAPPIST, and HARPS at the ESO 3.6 m telescope (Prog. IDs 087.C-0649, 089.C-0151, 090.C-0540)Photometric and radial velocities are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/568/A81

  5. Inter-lab testing of Hyalella azteca water and sediment methods: 3 Results from 10- to 42-d tests conducted with the new water-only method

    Science.gov (United States)

    Over the past four years, USEPA-Duluth, USGS-Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  6. Inter-lab testing of Hyalella azteca water and sediment methods: 1 Summary of 10- to 42-d data from 25 laboratories

    Science.gov (United States)

    Over the past four years, USEPA Duluth, USGS Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  7. Inter-lab testing of Hyalella azteca water and sediment methods: 1 background and overview of the 42-d survival, growth and reproduction test

    Science.gov (United States)

    Over the past four years, USEPA-Duluth, USGS-Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  8. Inter-lab testing of Hyalella azteca water and sediment methods: 4 Results from 10- to 42-d tests conducted with sediment substrates

    Science.gov (United States)

    Over the past four years, USEPA Duluth, USGS Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  9. Inter-lab testing of Hyalella azteca water and sediment methods: 4 Results from 10- to 42-d tests conducted with sediment substrates

    Science.gov (United States)

    Over the past four years, USEPA Duluth, USGS Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  10. Inter-lab testing of Hyalella azteca water and sediment methods: 1 Summary of 10- to 42-d data from 25 laboratories

    Science.gov (United States)

    Over the past four years, USEPA Duluth, USGS Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  11. Inter-lab testing of Hyalella azteca water and sediment methods: 1 background and overview of the 42-d survival, growth and reproduction test

    Science.gov (United States)

    Over the past four years, USEPA-Duluth, USGS-Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  12. Inter-lab testing of Hyalella azteca water and sediment methods: 3 Results from 10- to 42-d tests conducted with the new water-only method

    Science.gov (United States)

    Over the past four years, USEPA-Duluth, USGS-Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  13. Toxicity of bed sediments from the Niagara River Area of Concern and tributaries, New York, to Chironomus dilutus and Hyalella azteca, 2014-15

    Science.gov (United States)

    George, Scott D.; Baldigo, Barry P.; Duffy, Brian T.

    2016-09-20

    The Niagara River was designated as an Area of Concern in 1987 on both the United States and Canadian sides of the international boundary line because past industrial discharges and hazardous waste sites had caused extensive degradation of aquatic habitats. The degradation of the “benthos”, or the benthic macroinvertebrate community, was identified as one of seven beneficial use impairments caused by contaminated bed sediments. The U.S. Geological Survey and the New York State Department of Environmental Conservation, in cooperation with the U.S. Environmental Protection Agency, conducted a study in 2014 and 2015 to gather more extensive data on (a) the toxicity of bed sediments and (b) the status of macroinvertebrate communities on the main stem and tributaries of the Niagara River. This report addresses the first component of that study (toxicity of bed sediments), and summarizes results from laboratory toxicity tests that compare the survival and growth of two macroinvertebrate species between bed sediments from study sites and laboratory controls. Sediment toxicity was negligible at most sites, however poor performance of one or both test species in bed sediments from several tributary sites suggests that the quality of sediments may be adversely affecting benthic macroinvertebrate communities in some tributaries to the Niagara River.

  14. Measurement and reduction of porewater ammonia in 10-day sediment toxicity tests with marine amphipods

    Energy Technology Data Exchange (ETDEWEB)

    Kohn, N.P.; Karls, R.K.; Barrows, M.E. [Battelle/Marine Sciences Lab., Sequim, WA (United States)

    1994-12-31

    Ammonia is recognized as a potential contributor to amphipod toxicity in sediment bioassays, such as those required for dredged material testing. Measurement of ammonia in sediment porewater prior to testing and monitoring of ammonia during testing have not been routinely performed. The U.S. Environmental Protection Agency (EPA) and U.S. Army Corps of Engineers (USACE) have recently provided guidance for reducing sediment porewater ammonia by aeration and by exchange of overlying water prior to introducing test animals. In this study, two amphipod species, Rhepoxynius abronius and Eohaustorius estuarius, were exposed to eight sediment treatments in 10-day solid-phase static bioassays. Ammonia in sediment porewater was measured prior to testing; treatments with > 70 mg/L total ammonia were manipulated to reduce porewater ammonia in the test chambers to {<=}30 mg/L, following procedures in a memorandum by EPA and USACE. Porewater ammonia was also measured {approximately}24 h after test set up (when animals would normally be added), each day of manipulation before animals were added, and also on Days 5 and 9 for the E. estuarius test. The treatment with the highest porewater ammonia concentration was tested with and without manipulation. Reduction of porewater ammonia required up to 2 days. Toxicity was reduced in the manipulated sediments, but was statistically significant relative to control and reference treatments.

  15. The first hypothelminorheic Crustacea (Amphipoda, Dogielinotidae, Hyalella from South America

    Directory of Open Access Journals (Sweden)

    Stella Rodrigues

    2012-11-01

    Full Text Available Most of known troglobiotic species occur in caves and subterranean environments from great depths. However, recently more attention has been given to other subterranean environments, such as the hypothelminorheic habitats. It comprises the most superficial among all subterranean habitats. This kind of environment is characterized by the constant presence of wet spots, absence of light and very particular abiotic characteristics, comprising unique species. The first hypothelminorheic Amphipoda from South America is here described, a new species of the genus Hyalella which occurs in a wetland on Southern Brazil. The new species differs from other troglobiotics of the genus by the presence of a curved seta on the inner ramus of uropod 1 and elongation of appendices, as the first pair of antennae and peraeopods 6 and 7. However, human impacts in the area where the new species occurs have changed heavily their habitat, which may have led the species to a critical level of threat or even extinction, demonstrating the fragility of this environment.a

  16. First cytogenetic characterization of a species of the arboreal ant genus Azteca Forel, 1978 (Dolichoderinae, Formicidae).

    Science.gov (United States)

    Cardoso, Danon Clemes; Cristiano, Maykon Passos; Barros, Luísa Antônia Campos; Lopes, Denilce Meneses; Pompolo, Silvia das Graças

    2012-01-01

    In this paper we present, for the first time, a detailed karyotype characterization of a species of the genus Azteca (Dolichoderinae, Formicidae). Cerebral ganglia from Azteca trigona Emery, 1893 were excised and submitted to colchicine hypotonic solution and chromosomal preparations were analyzed through conventional staining with Giemsa, C-banding, silver nitrate staining (AgNO3) and sequential base-specific fluorochromes. The analysis shows that Azteca trigona has a diploid number of 28 chromosomes. The karyotype consists of five metacentric pairs, seven acrocentric pairs and two pseudo-acrocentric pairs, which represents a karyotype formula 2K= 10M + 14A + 4A(M) and a diploid number of the arms 2AN = 38. The analysis of heterochromatin distribution revealed a positive block on distal region of the short arm of fourth metacentric pair, which was coincident with Ag-NOR band and CMA3 fluorochrome staining, meaning that rDNA sequences are interspaced by GC-rich base pairs sequences. The C-banding also marked short arms of other chromosomes, indicating centric fissions followed by heterochromatin growth. The karyotype analysis of Azteca trigona allowed the identification of cytogenetic markers that will be helpful in a difficult taxonomic group as Azteca and discussion about evolutionary aspects of the genome organization.

  17. Diversification and phylogeographic structure in widespread Azteca plant-ants from the northern Neotropics.

    Science.gov (United States)

    Pringle, Elizabeth G; Ramírez, Santiago R; Bonebrake, Timothy C; Gordon, Deborah M; Dirzo, Rodolfo

    2012-07-01

    The Neotropical myrmecophytic tree Cordia alliodora hosts symbiotic Azteca ants in most of its widespread range. The taxonomy of the genus Azteca is notoriously difficult, which has frequently obscured species identity in ecological studies. We used sequence data from one mitochondrial and four nuclear loci to infer phylogenetic relationships, patterns of geographic distribution, and timing of diversification for 182 colonies of five C. alliodora-dwelling Azteca species from Mexico to Colombia. All morphological species were recovered as monophyletic, but we identified at least five distinct genetic lineages within the most abundant and specialized species, Azteca pittieri. Mitochondrial and nuclear data were concordant at the species level, but not within species. Divergence time analyses estimated that C. alliodora-dwelling Azteca shared a common ancestor approximately 10-22million years ago, prior to the proposed arrival of the host tree in Middle America. Diversification in A. pittieri occurred in the Pleistocene and was not correlated with geographic distance, which suggests limited historical gene flow among geographically restricted populations. This contrasts with the previously reported lack of phylogeographic structure at this spatial scale in the host tree. Climatic niches, and particularly precipitation-related variables, did not overlap between the sites occupied by northern and southern lineages of A. pittieri. Together, these results suggest that restricted gene flow among ant populations may facilitate local adaptation to environmental heterogeneity. Differences in population structure between the ants and their host trees may profoundly affect the evolutionary dynamics of this widespread ant-plant mutualism.

  18. Predation and aggressiveness in host plant protection: a generalization using ants from the genus Azteca

    Science.gov (United States)

    Dejean, Alain; Grangier, Julien; Leroy, Céline; Orivel, Jerôme

    2009-01-01

    In studying the ant genus Azteca, a Neotropical group of arboreal species, we aimed to determine the extent to which the ants use predation and/or aggressiveness to protect their host plants from defoliating insects. We compared a territorially dominant, carton-nester, Azteca chartifex, and three plant-ant species. Azteca alfari and Azteca ovaticeps are associated with the myrmecophyte Cecropia (Cecropiaceae) and their colonies shelter in its hollow branches; whereas Azteca bequaerti is associated with Tococa guianensis (Melastomataceae) and its colonies shelter in leaf pouches situated at the base of the laminas. Whereas A. bequaerti workers react to the vibrations transmitted by the lamina when an alien insect lands on a leaf making it unnecessary for them to patrol their plant, the workers of the three other species rather discover prey by contact. The workers of all four species use a predatory behaviour involving spread-eagling alien insects after recruiting nestmates at short range, and, in some cases, at long range. Because A. alfari and A. ovaticeps discard part of the insects they kill, we deduced that the workers’ predatory behaviour and territorial aggressiveness combine in the biotic defence of their host tree.

  19. Evolutionary history of the Azteca-like mariner transposons and their host ants

    Science.gov (United States)

    Palomeque, Teresa; Sanllorente, Olivia; Maside, Xulio; Vela, Jesús; Mora, Pablo; Torres, María I.; Periquet, Georges; Lorite, Pedro

    2015-08-01

    Three different complete mariner elements were found in the genome of the ant Tapinoma nigerrimum. One ( Tnigmar-Mr) was interrupted by a 900-bp insertion that corresponded to an incomplete member of a fourth mariner element, called Azteca. In this work, we isolate and characterize full-length Tnigmar-Az elements in T. nigerrimum. The purpose of this study is to clarify the evolutionary history of Azteca elements and their hosts as well as the possible existence of horizontal transfer processes. For this, Azteca-like elements were also retrieved from the available sequences of various ant genomes, representing four different ant subfamilies: Dolichoderinae, Formicinae, Myrmicinae, and Ponerinae. The tree topology resulting for the Azteca-like elements bore very little resemblance to that of their respective hosts. The pervasive presence of Azteca-like elements in all ant genomes, together with the observation that extant copies are usually younger than the genomes that host them, could be explained either by lineage sorting or by recent horizontal transfer of active elements. However, the finding of closer genetic relationships between elements than between the ants that host them is consistent with the latter scenario. This is clearly observed in Sinvmar-Az, Tnigmar-Az, Acepmar-Az, and Cflomar-Az elements, suggesting the existence of horizontal transfer processes. On the contrary, some elements displayed more divergence than did the hosts harboring them. This may reflect either further horizontal transfer events or random lineage sorting.

  20. Predation and aggressiveness in host plant protection: a generalization using ants from the genus Azteca.

    Science.gov (United States)

    Dejean, Alain; Grangier, Julien; Leroy, Céline; Orivel, Jerôme

    2009-01-01

    In studying the ant genus Azteca, a Neotropical group of arboreal species, we aimed to determine the extent to which the ants use predation and/or aggressiveness to protect their host plants from defoliating insects. We compared a territorially dominant, carton-nester, Azteca chartifex, and three plant-ant species. Azteca alfari and Azteca ovaticeps are associated with the myrmecophyte Cecropia (Cecropiaceae) and their colonies shelter in its hollow branches; whereas Azteca bequaerti is associated with Tococa guianensis (Melastomataceae) and its colonies shelter in leaf pouches situated at the base of the laminas. Whereas A. bequaerti workers react to the vibrations transmitted by the lamina when an alien insect lands on a leaf making it unnecessary for them to patrol their plant, the workers of the three other species rather discover prey by contact. The workers of all four species use a predatory behaviour involving spread-eagling alien insects after recruiting nestmates at short range, and, in some cases, at long range. Because A. alfari and A. ovaticeps discard part of the insects they kill, we deduced that the workers' predatory behaviour and territorial aggressiveness combine in the biotic defence of their host tree.

  1. Cuticular Hydrocarbon Cues Are Used for Host Acceptance by Pseudacteon spp. Phorid Flies that Attack Azteca sericeasur Ants.

    Science.gov (United States)

    Mathis, Kaitlyn A; Tsutsui, Neil D

    2016-04-01

    Parasitoids often use complex cues to identify suitable hosts in their environment. Phorid fly parasitoids that develop on one or a few host species often use multiple cues, ranging from general to highly specific, to home in on an appropriate host. Here, we describe the hierarchy of cues that Pseudacteon phorid flies use to identify Azteca ant hosts. We show, through behavioral observations in the field, that phorid flies are attracted to two cryptic Azteca species, but only attack Azteca sericeasur (Hymenoptera: Formicidae: Dolichoderinae). To test whether the phorid flies use cuticular hydrocarbons (CHCs) to distinguish between the two Azteca taxa, we first documented and compared cuticular hydrocarbons of the two Azteca taxa using gas chromatography/mass spectrometry. Then, using cuticular hydrocarbon-transfer experiments with live ants, we characterized the cuticular hydrocarbons of A. sericeasur as a short-range, host location cue used by P. lasciniosus (Diptera: Phoridae) to locate the ants.

  2. Las Armas de los Conquistadores. Las Armas de los Aztecas

    Directory of Open Access Journals (Sweden)

    Bruhn de Hoffmeyer, Ada

    1986-12-01

    Full Text Available ¿Qué clase de armas utilizaron los españoles en la conquista del Nuevo Mundo? No eran las mismas o idénticos tipos de armas en todas partes. Tampoco eran los mismos tipos y categorías que se utilizaban en aquella época en la Penínula Ibérica o en Europa occidental. Aunque los españoles llegaron al Nuevo Mundo con sus propias armas, fabricadas en España, en Italia, en Flandes, en Alemania —mejor dicho, en todo el mundo europeo del emperador Carlos V—, éstas no todas eran idóneas para los conquistadores de Méjico en el reino de los aztecas, o en Perú en el reino de los incas. Por varias razones. Las armas con que los conquistadores llegaron al Mundo Nuevo americano no eran completamente uniformes por razones económicas.

  3. A 10-days heatwave around flowering superimposed on climate change conditions significantly affects production of 22 barley accessions

    DEFF Research Database (Denmark)

    Ingvordsen, Cathrine Heinz; Lyngkjær, Michael F.; Peltonen-Sainio, Pirjo;

    2015-01-01

    representing a worst case scenario (~RCP8.5, IPCC) at the end of the 21st century. A 10 day-heatwave of 33/22°C (day/night) was superimposed around the time of flowering on the basic climate treatments. The superimposed heatwave decreased overall grain yield in all combinations, however, vast variation...

  4. Bayo Azteca, primera variedad mejorada de frijol con resistencia a Apion godmani Wagner Bayo Azteca, first improved bean variety with resistance to Apion godmani Wagner

    Directory of Open Access Journals (Sweden)

    Ramón Garza-García

    2010-12-01

    Full Text Available Bayo Azteca, la primera variedad mejorada de frijol (Phaseolus vulgaris L., con resistencia a una plaga insectil, ha sido obtenida por el programa de frijol del Campo Experimental Valle de México, del Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias por cruzas múltiples, esto involucró un largo proceso de mejora genética. Bayo Azteca es la primera variedad mejorada resistente al picudo del ejote (Apion godmani Wagner, un curculiónido que ataca al frijol en las zonas templadas de los valles altos de la Mesa Central de México, causando pérdidas que varían desde 50% hasta 90%. Al igual que otras variedades es también resistente a antracnosis [Colletotrichum lindemuthianum (Sacc & Magn. Briosi & Cav.] y tizón común [Xanthomonas campestris pv phaseoli (Smith Dye]. La nueva variedad fue desarrollada para los Valles Altos de la mesa central desde 1 800 a 2 300 m de altitud. Su hábito de crecimiento es indeterminado tipo III, guías cortas y flor blanca, las vainas son de tamaño mediano a grandes con 5 a 6 granos medianos, tiene alto potencial de rendimiento y plasticidad fenológica. En los Valles Altos, es de precocidad intermedia (102 a 118 días a madurez; Bayo Azteca es además de rápida cocción y con alto contenido de proteína.Bayo Azteca, the first improved bean variety (Phaseolus vulgaris L., with resistance to an insect plague, has been obtained via multiple crossing by bean program of the Valley of Mexico Experimental Station (CEVAMEX, of the National Research Forestry, Agriculture and Livestock Institute (INIFAP, which required a long process of genetic improvement. Bayo Azteca is the first improved variety resistant to bean pod weevil (Apion godmani Wagner, which is a curculionidae that attacks beans in template zones of the Central Highlands of Mexico and causes 50-90% losses. Similar to other varieties, the Bayo Azteca is resistant to anthracnose [Colletotrichum lindemuthianum (Sacc & Magn. Briosi

  5. The Effect of Symbiotic Ant Colonies on Plant Growth: A Test Using an Azteca-Cecropia System: e0120351

    National Research Council Canada - National Science Library

    Oliveira, Karla N; Coley, Phyllis D; Kursar, Thomas A; Kaminski, Lucas A; Moreira, Marcelo Z; Campos, Ricardo I

    2015-01-01

    .... In the field, we measured the growth of Cecropia glaziovii saplings and compared individuals that were naturally colonized by Azteca muelleri ants with uncolonized plants in different seasons (wet and dry...

  6. Flash Spectroscopy: Emission Lines from the Ionized Circumstellar Material around $<10$-Day-Old Type II Supernovae

    CERN Document Server

    Khazov, D; Gal-Yam, A; Manulis, I; Rubin, A; Kulkarni, S R; Arcavi, I; Kasliwal, M M; Ofek, E O; Cao, Y; Perley, D; Sollerman, J; Horesh, A; Sullivan, M; Filippenko, A V; Nugent, P E; Howell, D A; Cenko, S B; Silverman, J M; Ebeling, H; Taddia, F; Johansson, J; Laher, R R; Surace, J; Rebbapragada, U D; Wozniak, P R; Matheson, T

    2015-01-01

    Supernovae (SNe) embedded in dense circumstellar material (CSM) may show prominent emission lines in their early-time spectra ($\\leq 10$ days after the explosion), owing to recombination of the CSM ionized by the shock-breakout flash. From such spectra ("flash spectroscopy"), we can measure various physical properties of the CSM, as well as the mass-loss rate of the progenitor during the year prior to its explosion. Searching through the Palomar Transient Factory (PTF and iPTF) SN spectroscopy databases from 2009 through 2014, we found 12 Type II SNe showing flash-ionized (FI) signatures in their first spectra. All are younger than 10 days. These events constitute 14\\% of all 84 SNe in our sample having a spectrum within 10 days from explosion, and 18\\% of SNe~II observed at ages $<5$ days, thereby setting lower limits on the fraction of FI events. We classified as "blue/featureless" (BF) those events having a first spectrum which is similar to that of a black body, without any emission or absorption signa...

  7. FLASH SPECTROSCOPY: EMISSION LINES FROM THE IONIZED CIRCUMSTELLAR MATERIAL AROUND <10-DAY-OLD TYPE II SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Khazov, D.; Yaron, O.; Gal-Yam, A.; Manulis, I.; Rubin, A.; Ofek, E. O.; Horesh, A. [Benoziyo Center for Astrophysics, Faculty of Physics, The Weizmann Institute for Science, Rehovot 76100 (Israel); Kulkarni, S. R.; Kasliwal, M. M.; Cao, Y.; Perley, D. [Astronomy Department, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125 (United States); Arcavi, I.; Howell, D. A. [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93111 (United States); Sollerman, J. [The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, SE-10691 Stockholm (Sweden); Sullivan, M. [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Filippenko, A. V.; Nugent, P. E. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Cenko, S. B. [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Silverman, J. M. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Ebeling, H. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); and others

    2016-02-10

    Supernovae (SNe) embedded in dense circumstellar material (CSM) may show prominent emission lines in their early-time spectra (≤10 days after the explosion), owing to recombination of the CSM ionized by the shock-breakout flash. From such spectra (“flash spectroscopy”), we can measure various physical properties of the CSM, as well as the mass-loss rate of the progenitor during the year prior to its explosion. Searching through the Palomar Transient Factory (PTF and iPTF) SN spectroscopy databases from 2009 through 2014, we found 12 SNe II showing flash-ionized (FI) signatures in their first spectra. All are younger than 10 days. These events constitute 14% of all 84 SNe in our sample having a spectrum within 10 days from explosion, and 18% of SNe II observed at ages <5 days, thereby setting lower limits on the fraction of FI events. We classified as “blue/featureless” (BF) those events having a first spectrum that is similar to that of a blackbody, without any emission or absorption signatures. It is possible that some BF events had FI signatures at an earlier phase than observed, or that they lack dense CSM around the progenitor. Within 2 days after explosion, 8 out of 11 SNe in our sample are either BF events or show FI signatures. Interestingly, we found that 19 out of 21 SNe brighter than an absolute magnitude M{sub R} = −18.2 belong to the FI or BF groups, and that all FI events peaked above M{sub R} = −17.6 mag, significantly brighter than average SNe II.

  8. Twenty-four hours or 10 days? A prospective randomised controlled trial in children comparing head bandages following pinnaplasty.

    Science.gov (United States)

    Ramkumar, S; Narayanan, V; Laing, J H E

    2006-01-01

    The perceived benefits of bandaging for 10 days following pinnaplasty have been questioned by previous studies. The problems arising from these dressings are many [Powell BWEM. The value of head dressings in the postoperative management of the prominent ear. Br J Plast Surg 1989;42:692-4. Bartley J. How long should ears be bandaged after otoplasty? J Laryngol Otol 1998;112:531-2. Wong MC, Sylaidis P. Head dressings for pinnaplasty: a tradition not supported by evidence. Br J Plast Surg 2001;54:81-2], including their slippage [Powell BWEM. The value of head dressings in the postoperative management of the prominent ear. Br J Plast Surg 1989;42:692-4. Bradbury ET, Hewison J, Timmons MJ. Psychological and social outcome of prominent ear correction in children. Br J Plast Surg 1992;45:97-100. Jeffery SLA. Complications following correction of prominent ears: an audit review of 122 cases. Br J Plast Surg 1999;52:588-90]. Eighty children were recruited into a prospective randomised controlled trial comparing the use of a head bandage for only 24 h with a standard practise of a 10-day head bandage. A preoperative measurement of the lateral ear projection (LEP) was made. The outcome measures recorded during the two planned postoperative visits at 10 days (visit 1) and 2 months (visit 2) were: patient satisfaction score, LEP, complications and any unscheduled hospital visits associated with the surgery. There was no significant difference in LEP and patient satisfaction between the two groups at both the scheduled postoperative visits. Differences between the groups in the number of unscheduled visits (p=0.21) did not reach statistical significance. The findings indicate that it is safe and effective to use head bandage for only 24 h following surgical correction of prominent ears. This study shows no benefit from the application of a formal head bandage for any longer than 1 day.

  9. First cytogenetic characterization of a species of the arboreal ant genus Azteca Forel, 1978 (Dolichoderinae, Formicidae

    Directory of Open Access Journals (Sweden)

    Danon Cardoso

    2012-03-01

    Full Text Available In this paper we present, for the first time, a detailed karyotype characterization of a species of the genus Azteca (Dolichoderinae, Formicidae. Cerebral ganglia from Azteca trigona Emery, 1893 were excised and submitted to colchicine hypotonic solution and chromosomal preparations were analyzed through conventional staining with Giemsa, C-banding, silver nitrate staining (AgNO3 and sequential base-specific fluorochromes. The analysis shows that A. trigona has a diploid number of 28 chromosomes. The karyotype consists of five metacentric pairs, seven acrocentric pairs and two pseudo-acrocentric pairs, which represents a karyotype formula 2K= 10M + 14A + 4AM and a diploid number of the arms 2AN = 38. The analysis of heterochromatin distribution revealed a positive block on distal region of the short arm of fourth metacentric pair, which was coincident with Ag-NOR band and CMA3 fluorochrome staining, meaning that rDNA sequences are interspaced by GC-rich base pairs sequences. The C-banding also marked short arms of other chromosomes, indicating centric fissions followed by heterochromatin growth. The karyotype analysis of A. trigona allowed the identification of cytogenetic markers that will be helpful in a difficult taxonomic group as Azteca and discussion about evolutionary aspects of the genome organization.

  10. AZTECA, a y-y diagram oriented interactive computer program for optical system design and optimization

    Science.gov (United States)

    Flores-Hernandez, Ricardo

    1995-09-01

    The Centro de Investigaciones en Optica is developing the AZTECA optical design program to exploit the full synthesis capabilities intrinsic to Delano's y-y method. Both the y- y diagram and its dual the (omega) -(omega) diagram, are manipulated in real time to introduce changes at any point or line in those diagrams. These changes result in altered new versions of the optical system by means of a specialized subroutine that incorporates the fundamental synthesis equations for those diagrams. To display results on the computer's screen as the optimization process progress, AZTECA makes wide use of the fact that the y-y and the (omega) -(omega) diagrams display graphically all the first order attributes of an optical system. This program adjoins to these features the calculation of Buchdahl's 3rd, 5th, and 7th order aberration coefficients to the output. This results in a real time display of the system's paraxial and aberrational behavior. Efficient graphic displays, the program's modular structure and an interactive mode of operation, also contribute to make the AZTECA a versatile platform. It will be further developed as a new tool for efficient optical system design.

  11. Detecting trends in 10-day rainfall amounts at five sites in the state ofSão Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Gabriel Constantino Blain

    2014-09-01

    Full Text Available The temporal distribution of the rainfall events within a crop growing season plays a crucial role on the crop yield. In this way, the main goal of this study was to evaluate the presence of climate trends in the 10-day rainfall totalsobtained from five weather stations in the State of São Paulo, Brazil (1951-2012.The autocorrelation function, the Run test and the Durbin-Watson test indicateda lack of significant serial correlation in theseseries. The wavelet analysis revealed no conclusive evidence of periodicities in the temporal variability of this variable. According to the Mann-Kendall test, most of the 10-day rainfall amounts obtained from the five weather stations shows no significant trends. However, for the locations of States Campinas, Pindorama and Ribeirão Preto, the significant decreasing trends observed during the 2nd and 3rd ten days of October suggests a possible change in the climatic patterns of these locations, which may be linked to a delay in the return of the rainy season.

  12. Variation of the cholesterol content in breast milk during 10 days collection at early stages of lactation.

    Science.gov (United States)

    Kamelska, Anna M; Pietrzak-Fiećko, Renata; Bryl, Krzysztof

    2012-01-01

    More and more research is done concerning nutritional programming. Human milk nutrients which are consumed by infants can influence their health in later life. High level of cholesterol in human milk paradoxically lowers the cholesterol concentration in blood in adults. During the course of human lactation the cholesterol concentration decreases from 31 mg/100cm(3) (colostrum) to 16 mg/100 cm(3) (mature milk). According to Scopesi et al., 2002, Clin Nutr 21: 379-384, cholesterol concentration in mature milk ranged from 6.5 to 18.4 mg/100 cm(3). The aim of the study was to assess the variations in breast milk cholesterol content during 10 day collection at early lactation. 48 samples of human milk were analyzed. Mean age of women was 31 years. Women were collecting samples during 10 days of an early lactation stage (1-3 months after delivery). An Attenuated Total Reflectance Fourier Transformed Infrared (FTIR-ATR) method for easy and rapid determination of cholesterol in human milk was elaborated. Cholesterol content assessed by the FTIR method ranged from 3.36 to 12.98 mg/100 cm(3). Results indicate that milk cholesterol concentration during 10 consecutive days of early lactation is highly variable. Cholesterol content depends on an individual. Therefore it is suggested that not only the period of lactation but also mother's diet, age, season and place of residence are important factors determining cholesterol content.

  13. Responses of primary cultured haemocytes from the marine gastropod Haliotis tuberculata under 10-day exposure to cadmium chloride

    Energy Technology Data Exchange (ETDEWEB)

    Latire, Thomas; Le Pabic, Charles; Mottin, Elmina; Mottier, Antoine; Costil, Katherine; Koueta, Noussithe; Lebel, Jean-Marc [UMR 100 IFREMER ' Physiologie et Ecophysiologie des Mollusques Marins' - IFR 146 ICORE - IBFA - Universite de Caen Basse-Normandie, Campus 1, Science C, Esplanade de la Paix, 14032 Caen cedex (France); Serpentini, Antoine, E-mail: antoine.serpentini@unicaen.fr [UMR 100 IFREMER ' Physiologie et Ecophysiologie des Mollusques Marins' - IFR 146 ICORE - IBFA - Universite de Caen Basse-Normandie, Campus 1, Science C, Esplanade de la Paix, 14032 Caen cedex (France)

    2012-03-15

    Among metals, cadmium, a non-essential element, is an important pollutant that is released into aquatic environments. Due to its persistence and bioaccumulation, this metal has been shown to exert immunological effects on organisms. The objective of the present study was to investigate the in vitro effects of cadmium chloride using a haemocyte primary culture from the European abalone, Haliotis tuberculata. Most studies have maintained viable haemocytes in vitro for periods ranging from several hours to several days during acute exposures. Few investigations have reported the effects of metals using longer in vitro exposures, which are more realistic with regard to mimicking environmental conditions. In this study, we exposed abalone haemocytes to concentrations from 0.5 to 50,000 {mu}g L{sup -1} of CdCl{sub 2} for 10 days. The effects of cadmium chloride were reflected in a significant decrease in the number of viable cells and morphological modifications in a concentration-dependent manner beginning at a concentration of 500 {mu}g L{sup -1} as well as in some physiological processes, such as phagocytotic activity and the number of lysosome-positive cells. In contrast, phenoloxidase (PO) activity and reactive oxygen species (ROS) production were increased beginning at a concentration of 5 {mu}g L{sup -1}, which is consistent with environmental concentrations in polluted sites. For PO activity and ROS production, maximally 9-fold and 130% inductions, respectively, were recorded under the highest dose. These results thus indicate that cadmium chloride alters immune parameters of abalone haemocytes and that the long-term (10 days) primary culture system used here represents a suitable, sensitive in vitro model for assessing cytotoxic responses.

  14. Toxicity of Trinitrotoluene to Sheepshead Minnows in Water Exposures

    Science.gov (United States)

    2010-02-06

    more toxic than TNT to an amphipod Hyalella azteca (2 times) and the cladoceran Ceriodaphia dubia (30 times) (Griest et al., 1998). Substantial...the aquatic amphipod Hyalella Azteca . Ecotoxicol. Environ. Saf. 70, 38–46. Smock, L.A., Stoneburner, D.L., Clark, J.R., 1976. The toxic effects of...tetranitro-1,3,5,7-tetrazocine in sediments to Chironomus tentans and Hyalella azteca : low-dose hormesis and high-dose mortality. Environ. Toxicol. Chem. 21

  15. A 10-day vacancy period after cleaning and disinfection has no effect on the bacterial load in pig nursery units.

    Science.gov (United States)

    Luyckx, K; Millet, S; Van Weyenberg, S; Herman, L; Heyndrickx, M; Dewulf, J; De Reu, K

    2016-10-19

    Biosecurity measures such as cleaning, disinfection and a vacancy period between production cycles on pig farms are essential to prevent disease outbreaks. No studies have tested the effect of a longer vacancy period on bacterial load in nursery units. The present study evaluated the effect of a 10-day vacancy period in pig nursery units on total aerobic flora, Enterococcus spp., Escherichia coli, faecal coliforms and methicillin resistant Staphylococcus aureus (MRSA). Three vacancy periods of 10 days were monitored, each time applied in 3 units. The microbiological load was measured before disinfection and at 1, 4, 7 and 10 days after disinfection. No significant decrease or increase in E. coli, faecal coliforms, MRSA and Enterococcus spp. was noticed. Total aerobic flora counts were the lowest on day 4 after disinfection (i.e. 4.07 log CFU/625 cm(2)) (P disinfection, drinking nipples were still mostly contaminated with total aerobic flora (i.e. 5.32 log CFU/625 cm(2)) and Enterococcus spp. (i.e. 95 % of the samples were positive) (P disinfection with no extra biosecurity measures has no impact on the environmental load of total aerobic flora, E. coli, faecal coliforms, MRSA and Enterococcus spp..

  16. Pharmacodynamic effects of 3-day intravenous treatment with pantoprazole or ranitidine after 10 days of oral ranitidine.

    Science.gov (United States)

    Ley, L M; Becker, A; Lühmann, R; Sander, P; Lücker, P W

    2005-01-01

    Tachyphylaxis (drug tolerance) is an undesirable condition in drug therapy with histamine-2-receptor antagonists (H2RAs). The concept of overcoming tachyphylaxsis via intravenous (i.v.) administration of proton-pump inhibitors (PPIs) or H2RAs is of significant interest to physicians. In the present study, 32 healthy Helicobacter pylori negative male volunteers were evaluated for the ability of i.v. pantoprazole or i.v. ranitidine to overcome oral ranitidine tachyphylaxis. After 10 days of oral treatment with enteric-coated 300-mg ranitidine tablets once daily in the evening, two groups of 16 volunteers each were randomized to receive either i.v. pantoprazole or i.v. ranitidine for up to 72 h. The primary variable was defined as the increase in 24-h gastric pH median after 1 day of i.v. treatment; the secondary variable was median percentage of time that 24-h gastric pH was ranitidine treatment, tachyphylaxis was present in all volunteers. Within 1 day of continuous i.v. pantoprazole or i.v. ranitidine administration, 24-h median gastric pH increased from pH 1.45 to pH 3.50 (241%) and from pH 1.50 to pH 2.35 (157%), respectively. I.v. pantoprazole was found to be significantly more effective (pranitidine in increasing the 24-h gastric pH after oral ranitidine tachyphylaxis.

  17. Final Remedial Investigation/Baseline Risk Assessment for the Ravines and Beach Area Study of the Surplus Operable Unit, Fort Sheridan, Illinois. Volume 1: RI Text and RI Appendices A-I.

    Science.gov (United States)

    2007-11-02

    conducted on the invertebrates Hyalella azteca (H. azteca ) and Lumbriculus variegatus (L. variegatus). Groundwater acute toxicity tests were...control sediment tissue sample. Whole sediment chronic toxicity tests conducted with H. azteca in Janes Ravine sediment did not demonstrate any...Illinois the control sediment tissue sample. Whole sediment chronic toxicity tests conducted with H. azteca in Hutchinson Ravine sediment did not

  18. Comparative study of 5-day cefcapene-pivoxil and 10-day amoxicillin or cefcapene-pivoxil for treatment of group A streptococcal pharyngitis in children.

    Science.gov (United States)

    Sakata, Hiroshi

    2008-06-01

    In order to compare the bacteriological and clinical efficacy and safety of cefcapene-pivoxil (CFPN-PI) for 5 days, CFPN-PI for 10 days, and amoxicillin (AMPC) for 10 days for the treatment of pharyngitis due to group A beta-hemolytic streptococcus (GAS) in children, a prospective multicenter randomized open-label comparative study was performed with 12 pediatric clinics in Asahikawa between June 2006 and February 2007. Two hundred and fifty children (age range 6 months to 12 years) with signs and symptoms of acute pharyngitis were enrolled. All had a positive throat culture for GAS and were fully evaluable. Eighty-two patients received CFPN-PI 9-10 mg/kg/day three times a day for 5 days, 88 received CFPN-PI three times a day for 10 days, and 80 received AMPC three times a day for 10 days. The CFPN-PI for 5 days regimen, the CFPN-PI for 10 days regimen, and the AMPC for 10 days regimen produced bacteriological eradication at the end of treatment in 93.8%, 96.2%, and 91.7% of the patients, respectively. The clinical cure rate observed at the end of therapy was 100% of the patients in the three groups. Relapse rates were 1.3% in CFPN-PI for 5 days, 4.0% in CFPN-PI for 10 days, and 2.9% in AMPC for 10 days. There were no significant differences in eradication rate, clinical cure rate, and relapse rate between the three treatment groups. The only adverse effects were infrequent diarrhea in all three groups, and a rash which occurred in 6 patients (8.0%) of the AMPC treatment group. Five days of treatment with CFPN-PI was as efficacious in bacteriological eradication and clinical response as 10 days of CFPN-PI or AMPC treatment.

  19. Pairing and reproductive success in two sympatric species of Hyalella (Crustacea, Amphipoda, Dogielinotidae) from southern Brazil

    Science.gov (United States)

    da Silva Castiglioni, Daniela; Bond-Buckup, Georgina

    2008-01-01

    This study aimed at characterizing pairing and reproductive success in relation to male and female sizes of the sympatric freshwater gammarideans Hyalella pleoacuta and H. castroi from southern Brazil. These amphipods exhibit precopulatory mate guarding, in which a male will carry a potential mate beneath its ventral surface, guarding the female for several days until it molts and lays its eggs. The specimens were collected monthly with nets, from November 2003 to July 2004 in two trout aquaculture ponds at Sítio Vale das Trutas locality, São José dos Ausentes County, southern Brazil. The precopulatory pairs and ovigerous females were identified and separated in the field. In the laboratory, they were measured (cephalothorax length in mm), using a micrometer eyepiece in a stereoscopic microscope. Pairing success was estimated from the proportion of mating males and females related to their respective non-pairing individuals by size classes. Reproductive success was estimated from egg production. The mean cephalothorax length of paired males was larger than that of the unpaired males. For females, however, body size not affect pairing success for either species, because mean cephalothorax length of paired females did not differ significantly from unpaired females. Paired and unpaired males of both species of Hyalella were larger than the females. Positive assortative mating by size was observed in both species; i.e., larger males tended to pair with larger females. Male pairing success increased sharply with size. In both species, reproductive success in males increased with body size; however, the females of intermediate size classes showed greater reproductive success. This result supports the hypothesis that loading constraints play a part in structuring size-assortative pairing in these species.

  20. Parasite Lost: Chemical and Visual Cues Used by Pseudacteon in Search of Azteca instabilis.

    Science.gov (United States)

    Mathis, Kaitlyn A; Philpott, Stacy M; Moreira, Rayane F

    2011-05-01

    An undescribed species of phorid fly (genus: Pseudacteon) parasitizes the ant Azteca instabilis F Smith, by first locating these ants through the use of both chemical and visual cues. Experiments were performed in Chiapas, Mexico to examine a) the anatomical source of phorid attractants, b) the specific chemicals produced that attract phorids, and c) the nature of the visual cues used by phorids to locate the ants. We determined that phorid-attracting chemicals were present within the dorsal section of the abdomen, the location of the pygidial gland. Further experiments indicate that a pygidial gland compound, 1-acetyl-2-methylcyclopentane, is at least partially responsible for attracting phorid flies to their host. Finally, although visual cues such as movement were important for host location, size and color of objects did not influence the frequency with which phorids attacked moving targets.

  1. Toxicological Effects of Military Smokes and Obscurants on Aquatic Threatened and Endangered Species

    Science.gov (United States)

    2008-11-10

    Photooxidation products of smoke generator fuel (SGF) No. 2 fog oil and toxicity to Hyalella azteca . Env Toxicol & Chem 7:753-762. Quist MC, Fay PA...Brewer-Swarz S, and Thoeny WT (1997) A reformulated, reconstituted water for testing the freshwater amphipod, Hyalella azteca . Environ Toxicol & Chem 16

  2. Comparação metodológica de testes de toxicidade com Hyalella azteca (Crustacea, Amphipoda) e avaliação da qualidade do sedimento em reservatórios do rio Tietê (SP)

    OpenAIRE

    Ana Paula Cristiano do Nascimento

    2003-01-01

    O presente trabalho fez parte do Projeto QualiSed, uma cooperação entre UFSCar, Unicamp e Cetesb, o qual realizou um levantamento das bases técnico-científicas para a derivação de critérios de qualidade de sedimentos (CQS) para proteção da fauna aquática dos ecossistemas. Nos últimos anos tem havido um grande interesse no desenvolvimento, aperfeiçoamento e aplicação de metodologias para avaliar o grau de contaminação de sedimentos. Estes, apesar de fornecerem habitat para muitos organismos aq...

  3. Efficacy, safety and tolerability of 3 day azithromycin versus 10 day co-amoxiclav in the treatment of children with acute lower respiratory tract infections

    NARCIS (Netherlands)

    A. Ferwerda (Annemarie); H.A. Moll (Henriëtte); W.C.J. Hop (Wim); J.M. Kouwenberg (Jan); C.V. Tjon Pian Gi

    2001-01-01

    textabstractTo compare the efficacy, safety and tolerability of a 3 day course of azithromycin with a 10 day course of co-amoxiclav in the treatment of children with acute lower respiratory tract infection (LRTI), 118 patients with community-acquired LRTI were included

  4. Nest structure and occurrence of three species of Azteca (Hymenoptera, Formicidae in Cecropia pachystachya (Urticaceae in non-floodable and floodable pantanal areas Arquitetura de ninho e ocorrência de três espécies de Azteca (Hymenoptera, Formicidae em Cecropia pachystachya (Urticaceae em ambiente alagável e não alagável no Pantanal

    Directory of Open Access Journals (Sweden)

    Alexsandro S. Vieira

    2010-01-01

    Full Text Available Thirty Cecropia pachystachya trees were examined in non-floodable and floodable areas to investigate the association between C. pachystachya and Azteca ants in the Pantanal of Mato Grosso do Sul, Brazil. The species Azteca ovaticeps, Azteca isthmica, and Azteca alfari were found nesting inside domatia of C. pachystachya. A. ovaticeps was the most frequent species in the trees in the floodable area, while A. isthmica and A. alfari, in the non-floodable area. A. ovaticeps and A. isthmica maintained more entrance/exit holes in comparison to A. alfari. All Azteca species maintained entrance/exit holes in the closest domatia to the apical area of the branch, due to proximity to Müllerian and pearl bodies, suggesting that these species of Azteca were influenced by their environment during evolution and became specialized. All internodal septa of each examined branch were perforated by ants, indicating the branches were inhabited by a single colony.Foram analisadas 30 plantas de Cecropia pachystachya em cada ambiente alagável e não alagável no Pantanal sul-mato-grossense, Brasil, com o objetivo de investigar a associação entre formigas Azteca e C. pachystachya. Foram encontradas as espécies Azteca ovaticeps, Azteca isthmica e Azteca alfari nidificando nas domáceas da planta. A. ovaticeps foi mais frequente em plantas de área alagável, enquanto A. isthmica e A. alfari em plantas em área não alagável. A. ovaticeps e A. isthmica apresentaram maior quantidade de orifícios de entrada/saída em relação à A. alfari e todas as espécies mantêm próximo da região apical do ramo, orifícios de entrada/saída nas domáceas, devido à proximidade com os corpúsculos müellerianos e pérola. Isto é, essas espécies de Azteca especializaram-se ao longo da evolução influenciadas pelo ambientes. Todos os septos internodais de cada ramo analisados apresentaram-se perfurados pelas formigas, sugerindo que os mesmos são habitados por uma única colônia.

  5. Revisión de la distribución de Hyalella Smith, 1874 (Crustacea, Amphipoda en la Patagonia e islas adyacentes Revision of the distribution of Hyalella Smith, 1874 (Crustacea, Amphipoda in Patagonia and adjacent islands

    Directory of Open Access Journals (Sweden)

    Patricio De los Ríos-Escalante

    2012-07-01

    Full Text Available Se realiza una revisión de las especies de anfípodos del género Hyalella en aguas continentales de la Patagonia, isla Tierra del Fuego, Reserva de la Biosfera de Cabo de Hornos e islas adyacentes (38-54°S. Esta zona austral presenta numerosos tipos de ambientes acuáticos continentales como lagos, humedales y arroyos, y las principales especies en ambientes bentónicos corresponden a anfípodos del género Hyalella. La bibliografía menciona la presencia de H. costera, H. chiloensis, H. falklandensis, H. franciscae, H. neonoma, H. patagónica, H. rionegrina y H. simplex. La distribución de estas especies concuerda con estudios biogeográficos sobre la presencia de especies endémicas y de amplia distribución en el sur de la Patagonia y zona subantárticas. A pesar de la presencia de especies depredadoras introducidas, sobre la base de la literatura, los anfípodos serían más abundantes debido a la presencia de materia orgánica particulada.This study reviews the amphipod species of the genus Hyalella in the inland waters of Patagonia, Tierra del Fuego Island, Cape Horn Biosphere Reserve, and adjacent islands (38-54°S. This southern zone has numerous kinds of continental water bodies such as lakes, wetlands, and streams, and the main species in benthic assemblages are amphipods of the genus Hyalella. The literature mentions the presence of H. costera, H. chiloensis, H. falklaidensis, H. franciscae, H. neonoma, H. patagonica, H. rionegrina, and H. simplex. The distribution of these species agrees with biogeographical studies about the presence of widespread, endemic species in southern Patagonia and the sub-Antarctic zone. In spite of the presence of introduced predatory species, the literature indicates that the amphipods are more abundant due to the presence of particulated organic matter.

  6. Simulation Modeling of Zooplankton and Benthos in Reservoirs: Documentation and Development of Model Constructs.

    Science.gov (United States)

    1980-03-01

    des conditions ecologiques. Cahiers de Biologie Marine, 17: 37-43. BOVEE, E. C. 1949. Studies on the thermal death rate of Hyallela azteca , Saussure...1965. Dynamics and production of a natural population of fresh-water amphipod, Hyalella azteca . Ecological Monographs, 35: 377-394. CORNER, E. D. S...B. T. 1970. The utilization of benthic microflora by Hyalella azteca (Amphipoda). Journal of Animal Ecology, 39: 427-437. HARGRAVE, B. T. 1971. An

  7. Rational Selection of Tailored Amendment Mixtures and Composites for In Situ Remediation of Contaminated Sediments

    Science.gov (United States)

    2008-12-01

    toxicity observed for Thiol-SAMMS was moderate at a dose of 5% by dry weight with a reduction in H. Azteca survival from 98% to 73%. Although Thiol...arenaceodentata, Chironomus dilutus, Hyalella Azteca and Leptocheirus plumulosus. Tests were conducted as described in existing chronic sediment toxicity test...illustrates the survival of three benthic organisms (Chironomus dilutus (a), Hyalella Azteca (b) and Leptocheirus plumulosus(c) in the amendment treated

  8. Plant defense, herbivory, and the growth of Cordia alliodora trees and their symbiotic Azteca ant colonies.

    Science.gov (United States)

    Pringle, Elizabeth G; Dirzo, Rodolfo; Gordon, Deborah M

    2012-11-01

    The effects of herbivory on plant fitness are integrated over a plant's lifetime, mediated by ontogenetic changes in plant defense, tolerance, and herbivore pressure. In symbiotic ant-plant mutualisms, plants provide nesting space and food for ants, and ants defend plants against herbivores. The benefit to the plant of sustaining the growth of symbiotic ant colonies depends on whether defense by the growing ant colony outpaces the plant's growth in defendable area and associated herbivore pressure. These relationships were investigated in the symbiotic mutualism between Cordia alliodora trees and Azteca pittieri ants in a Mexican tropical dry forest. As ant colonies grew, worker production remained constant relative to ant-colony size. As trees grew, leaf production increased relative to tree size. Moreover, larger trees hosted lower densities of ants, suggesting that ant-colony growth did not keep pace with tree growth. On leaves with ants experimentally excluded, herbivory per unit leaf area increased exponentially with tree size, indicating that larger trees experienced higher herbivore pressure per leaf area than smaller trees. Even with ant defense, herbivory increased with tree size. Therefore, although larger trees had larger ant colonies, ant density was lower in larger trees, and the ant colonies did not provide sufficient defense to compensate for the higher herbivore pressure in larger trees. These results suggest that in this system the tree can decrease herbivory by promoting ant-colony growth, i.e., sustaining space and food investment in ants, as long as the tree continues to grow.

  9. Mycelial carton galleries of Azteca brevis (Formicidae) as a multi-species network

    Science.gov (United States)

    Mayer, Veronika E.; Voglmayr, Hermann

    2009-01-01

    Apart from growing fungi for nutrition, as seen in the New World Attini, ants cultivate fungi for reinforcement of the walls of their nests or tunnel-shaped runway galleries. These fungi are grown on organic material such as bark, epiphylls or trichomes, and form stable ‘carton structures’. In this study, the carton of the runway galleries built by Azteca brevis (Formicidae, Dolichoderinae) on branches of Tetrathylacium macrophyllum (Flacourtiaceae) is investigated. For the first time, molecular tools are used to address the biodiversity and phylogenetic affinities of fungi involved in tropical ant carton architecture, a previously neglected ant–fungus mutualism. The A. brevis carton involves a complex association of several fungi. All the isolated fungi were unequivocally placed within the Chaetothyriales by DNA sequence data. Whereas five types of fungal hyphae were morphologically distinguishable, our DNA data showed that more species are involved, applying a phylogenetic species concept based on DNA phylogenies and hyphal morphology. In contrast to the New World Attini with their many-to-one (different ant species—one fungal cultivar) pattern, and temperate Lasius with a one-to-two (one ant species—two mutualists) or many-to-one (different ant species share the same mutualist) system, the A. brevis–fungi association is a one-to-many multi-species network. Vertical fungus transmission has not yet been found, indicating that the A. brevis–fungi interaction is rather generalized. PMID:19556257

  10. Comparative Study of 5-Day and 10-Day Cefditoren Pivoxil Treatments for Recurrent Group A β-Hemolytic Streptococcus pharyngitis in Children

    Directory of Open Access Journals (Sweden)

    Hideaki Kikuta

    2009-01-01

    Full Text Available Efficacy of short-course therapy with cephalosporins for treatment of group A β-hemolytic streptococcus (GABHS pharyngitis is still controversial. Subjects were 226 children with a history of at least one episode of GABHS pharyngitis. Recurrence within the follow-up period (3 weeks after initiation of therapy occurred in 7 of the 77 children in the 5-day treatment group and in 1 of the 149 children in the 10-day treatment group; the incidence of recurrence being significantly higher in the 5-day treatment group. Bacteriologic treatment failure (GABHS isolation without overt pharyngitis at follow-up culture was observed in 7 of the 77 children in the 5-day treatment group and 17 of the 149 children in the 10-day treatment group. There was no statistical difference between the two groups. A 5-day course of oral cephalosporins is not always recommended for treatment of GABHS pharyngitis in children who have repeated episodes of pharyngitis.

  11. Influence of a 10-Day Mimic of Our Ancient Lifestyle on Anthropometrics and Parameters of Metabolism and Inflammation: The “Study of Origin”

    Science.gov (United States)

    Ruiz-Núñez, Begoña; Raison, Charles L.; Muskiet, Frits A. J.

    2016-01-01

    Chronic low-grade inflammation and insulin resistance are intimately related entities that are common to most, if not all, chronic diseases of affluence. We hypothesized that a short-term intervention based on “ancient stress factors” may improve anthropometrics and clinical chemical indices. We executed a pilot study of whether a 10-day mimic of a hunter-gatherer lifestyle favorably affects anthropometrics and clinical chemical indices. Fifty-five apparently healthy subjects, in 5 groups, engaged in a 10-day trip through the Pyrenees. They walked 14 km/day on average, carrying an 8-kilo backpack. Raw food was provided and self-prepared and water was obtained from waterholes. They slept outside in sleeping bags and were exposed to temperatures ranging from 12 to 42°C. Anthropometric data and fasting blood samples were collected at baseline and the study end. We found important significant changes in most outcomes favoring better metabolic functioning and improved anthropometrics. Coping with “ancient mild stress factors,” including physical exercise, thirst, hunger, and climate, may influence immune status and improve anthropometrics and metabolic indices in healthy subjects and possibly patients suffering from metabolic and immunological disorders. PMID:27366752

  12. Influence of a 10-Day Mimic of Our Ancient Lifestyle on Anthropometrics and Parameters of Metabolism and Inflammation: The “Study of Origin”

    Directory of Open Access Journals (Sweden)

    Leo Pruimboom

    2016-01-01

    Full Text Available Chronic low-grade inflammation and insulin resistance are intimately related entities that are common to most, if not all, chronic diseases of affluence. We hypothesized that a short-term intervention based on “ancient stress factors” may improve anthropometrics and clinical chemical indices. We executed a pilot study of whether a 10-day mimic of a hunter-gatherer lifestyle favorably affects anthropometrics and clinical chemical indices. Fifty-five apparently healthy subjects, in 5 groups, engaged in a 10-day trip through the Pyrenees. They walked 14 km/day on average, carrying an 8-kilo backpack. Raw food was provided and self-prepared and water was obtained from waterholes. They slept outside in sleeping bags and were exposed to temperatures ranging from 12 to 42°C. Anthropometric data and fasting blood samples were collected at baseline and the study end. We found important significant changes in most outcomes favoring better metabolic functioning and improved anthropometrics. Coping with “ancient mild stress factors,” including physical exercise, thirst, hunger, and climate, may influence immune status and improve anthropometrics and metabolic indices in healthy subjects and possibly patients suffering from metabolic and immunological disorders.

  13. The Azteca Chess experience: learning how to share concepts of ecological complexity with small coffee farmers

    Directory of Open Access Journals (Sweden)

    Luís García-Barrios

    2017-06-01

    Full Text Available Small-scale coffee farmers understand certain complex ecological processes, and successfully navigate some of the challenges emerging from the ecological complexity on their farms. It is generally thought that scientific knowledge is able to complement farmers' knowledge. However, for this collaboration to be fruitful, the gap between the knowledge frameworks of both farmers and scientists will need to be closed. We report on the learning results of 14 workshops held in Chiapas, Mexico during 2015 in which 117 small-scale coffee farmers of all genders (30% women and ages who had little schooling were exposed by researchers to a natural history narrative, a multispecies network representation, a board game, and a series of graphical quizzes, all related to a nine-species complex ecological network with potential for autonomous control of the ongoing and devastating coffee rust epidemic that was affecting them. Farmers' retention and understanding of direct and indirect bilateral interactions among organisms was assessed with different methods to elucidate the effect of adding Azteca Chess gaming sessions to a detailed and very graphical lecture. Evaluation methods that were better adapted to farmers' conditions improved learning scores and showed statistically significant age effect (players older than 40 had lower retention scores and gaming effect (lower retention of interactions included in the lecture but not in the game. The combination of lecture and game sessions helped participants better understand cascades of trait-mediated interactions. Participants' debriefings confirmed qualitatively that they learned that beneficial organisms and interactions occur on their farms, and that gaming was enjoyable, motivating, and critical to grasp complex interactions. Many of the farmers concluded that the outcome of these interactions is not unique and not always in favor of rust control but is context dependent. Many concluded that there are

  14. T-condylar fracture delayed for 10 days in a 5-year-old boy: a case report and review of the literature

    Institute of Scientific and Technical Information of China (English)

    Shashidhar B Kantharajanna; Vijay Goni; Pebam Sudesh; Nirmal Raj Gopinathan

    2013-01-01

    T-condylar fracture is rare in paediatric age group,especially in skeletally immature children less than 9 years old,with very few cases reported in available literature.We present such a case in a 5 year old child that was initially managed as a supracondylar fracture at another centre before referral to us,10 days after the injury.The child was diagnosed as having a displaced T-condylar fracture on plain radiograph.Open reduction and internal fixation with K-wires was performed.At 2 years follow-up,the child had good range of motion at elbow with 5°of cubitus varus.With this background we discuss the pertinent principles of management of T-condylar fractures in skeletally immature children.

  15. T-condylar fracture delayed for 10 days in a 5-year-old boy: a case report and review of the literature

    Directory of Open Access Journals (Sweden)

    Kantharajanna Shashidhar B

    2013-02-01

    Full Text Available 【Abstract】 T-condylar fracture is rare in paediatric age group, especially in skeletally immature children less than 9 years old, with very few cases reported in available literature. We present such a case in a 5 year old child that was initially managed as a supracondylar fracture at an-other centre before referral to us, 10 days after the injury. The child was diagnosed as having a displaced T-condylar fracture on plain radiograph. Open reduction and internal fixation with K-wires was performed. At 2 years follow-up, the child had good range of motion at elbow with 5 o of cubi-tus varus. With this background we discuss the pertinent principles of management of T-condylar fractures in skele-tally immature children. Key words: Humeral fractures; Fracture fixation; Fracture healing; Child

  16. Persistent high fever for more than 10 days during acute phase is a risk factor for endothelial dysfunction in children with a history of Kawasaki disease.

    Science.gov (United States)

    Mori, Yasuhiko; Katayama, Hiroshi; Kishi, Kanta; Ozaki, Noriyasu; Shimizu, Tatsuo; Tamai, Hiroshi

    2016-07-01

    Endothelial dysfunction has previously been reported in children with a history of Kawasaki disease, but the determinants of endothelial function in Kawasaki disease patients are still unknown. In this study, we investigated endothelial function in Kawasaki disease patients and attempted to identify risk factors for persistent endothelial dysfunction. Using high-resolution ultrasound, we measured the percent flow-mediated dilatation, an arterial response to reactive hyperemia, to evaluate endothelial function in 67 patients with a history of Kawasaki disease and 28 age- and sex-matched control subjects. We divided the Kawasaki disease patients into a group with impaired endothelial function (the percent flow-mediated dilatation below -2 standard deviations of the control group) and a group with normal endothelial function (the percent flow-mediated dilatation more than -2 standard deviations of control). Logistic multiple regression analysis was performed to identify independent predictors of impaired endothelial function. In Kawasaki disease patients, the percent flow-mediated dilatation was significantly lower than in the control subjects (9.8±3.6%, compared with 13.1±3.4%, pKawasaki disease patients (3 patients with coronary artery lesions and 10 patients without coronary artery lesions), the percent flow-mediated dilatation was below -2 standard deviations of control. Logistic multiple regression analysis showed that a febrile period of longer than 10 days during the acute phase was the significant risk factor for endothelial dysfunction (odds ratio: 8.562; 95% confidence interval: 1.366-53.68). Presence of coronary artery lesions was not a determinant of endothelial dysfunction. Systemic endothelial dysfunction exists in children with a history of Kawasaki disease, and a febrile period of longer than 10 days during the acute phase is an independent predictor of endothelial dysfunction irrespective of coronary artery involvement. Copyright © 2015 Japanese

  17. Comparison of clinical efficacy between 3-day combined clavulanate/amoxicillin preparation treatment and 10-day amoxicillin treatment in children with pharyngolaryngitis or tonsillitis.

    Science.gov (United States)

    Kuroki, Haruo; Ishiwada, Naruhiko; Inoue, Nobue; Ishikawa, Nobuyasu; Suzuki, Hiroshi; Himi, Kyoko; Kurosaki, Tomomichi

    2013-02-01

    The efficacy of 3-day treatment with a combined clavulanate/amoxicillin preparation (Clavamox combination dry syrup for pediatric cases) and 10-day treatment with amoxicillin against pediatric pharyngolaryngitis and tonsillitis caused by Group A β-hemolytic Streptococcus was compared. Among the patients included in the efficacy evaluation (54 from the clavulanate/amoxicillin group and 43 from the amoxicillin group), the clinical response rate on completion of treatment was 98.1 % in the clavulanate/amoxicillin group and 92.9 % in the amoxicillin group, thus supporting the equivalent efficacy of these two therapies. The Group A β-hemolytic Streptococcus eradication rate at approximately 1-2 weeks after completion/discontinuation of treatment was 65.4 % in the clavulanate/amoxicillin group and 85.4 % in the amoxicillin group. Even in cases from which the pathogen continued to be isolated, relapse/recurrence of clinical symptoms was seldom seen. Urinalysis, conducted to assess the presence or absence of acute glomerulonephritis, revealed no abnormality in any patient. These results suggest that 3-day treatment with this clavulanate/amoxicillin preparation is expected to provide a valid means of treating pediatric pharyngolaryngitis and tonsillitis caused by Group A β-hemolytic Streptococcus.

  18. Eclipse Impact on a Remote Sensing Data Set: PAL NDVI 10-Day Composite from February 11 to 20 in 1999 for Western Australia

    Directory of Open Access Journals (Sweden)

    Chai K. Lim

    2010-08-01

    Full Text Available Pathfinder Normalized Difference Vegetation Index (NDVI derived from Channel 1 (Red and Channel 2 (near-infrared of Advanced Very High Resolution Radiometer (AVHRR onboard NOAA 14 became abnormally high for the 10-day composite from February 11 to 20 in 1999 for Western Australia. There was a solar eclipse in the satellite path on February 16 about the same time when NOAA 14 was above the eclipse location, causing the Channel 1 value to be 0 in many cells. The NDVI composite updating rule was to capture the greenest condition of each composite period. There seems to have been a possible lack of quality control during the NDVI composite generation, which could have caused the abnormally high NDVI values. However, there were some cells within the affected area that had values close to normal for NDVI as well as Channel 1 and Channel 2. The abnormal NDVI data values could have been avoided by not using the data obtained during the eclipse in the generation of the composite. Further investigation on those cells which were not affected by the eclipse is suggested for a better quality control of remote sensing data obtained during eclipse occurrences.

  19. [Incidence and mortality of common neonatal diseases in the foal during the first 10 days post natum in a veterinary hospital].

    Science.gov (United States)

    Graßl, Martin; Ulrich, Tina; Wehrend, Axel

    2017-09-13

    The aim of this study was to present the incidence and lethality of diseases in foals during the first 10 days following birth by analyzing patient data. Over a period of 6 years, patient data from 393 foals, that had been presented within the first 10 days after birth in a hospital, were evaluated. The number of diseases, the sex of the affected foals and the lethality were documented. A total of 28 diseases were diagnosed, with systemic inflammatory response syndrome (SIRS), meconium impaction and bronchopneumonia being the most frequent diagnoses. The mortality rate for SIRS was 41.8%, for meconium impaction 29.7% and for bronchopneumonia 37.9%. The mean time of death for patients with SIRS was 4.2   ±   2.9 days, for patients with meconium impaction 4.6 ± 3.2 days and for foals suffering from bronchopneumonia 5.2    ±   3.5 days post partum. Based on the data collection, the frequency and thus the importance of individual disease patterns can be deduced. The information on lethality helps to make predictions for the prognosis of the most common neonatal foal diseases based on first diagnosis.

  20. EPIC 211391664b: A 32-M$_\\oplus$ Neptune-sized planet in a 10-day orbit transiting an F8 star

    CERN Document Server

    Barragán, Oscar; Gandolfi, Davide; Fridlund, Malcolm; Endl, Michael; Deeg, Hans J; Cagigal, Manuel P; Lanza, Antonino F; Moroni, Pier G Prada; Smith, Alexis; Korth, Judith; Bedell, Megan; Cabrera, Juan; Cochran, William D; Cusano, Felice; Csizmadia, Szilard; Eigmüller, Philipp; Erikson, Anders; Guenther, Eike W; Hatzes, Artie P; Nespral, David; Pätzold, Martin; Prieto-Arranz, Jorge; Rauer, Heike

    2016-01-01

    We report the discovery of EPIC 211391664b, a transiting Neptune-sized planet monitored by the K2 mission during its campaign 5. We combine the K2 time-series data with ground-based photometric and spectroscopic follow-up observations to confirm the planetary nature of the object and derive its mass, radius, and orbital parameters. EPIC 211391664 b is a warm Neptune-like planet in a 10-day orbit around a V=12.2~mag F-type star with $M_\\star$=$ 1.074\\pm0.042 M_{\\odot} $, $R_\\star$=$ 1.311 ^{+ 0.083}_{ - 0.048} R_{\\odot}$, and age of $5.2_{-1.0}^{+1.2}$~Gyr. We derive a planetary mass and radius of $M_\\mathrm{p}$=$ 32.2 \\pm 8.1 M_{\\oplus}$ and $R_\\mathrm{p}$=$4.3^{+0.3}_{-0.2} R_{\\oplus}$. EPIC 211391664b joins the relatively small group of Neptune-sized planets whose mass and radius have been derived with a precision better than 3-$\\sigma$. We estimate that the planet will be engulfed by EPIC 211391664 in $\\sim$3~Gyr, due to the evolution of the host star towards the red giant branch.

  1. Cascading model uncertainty from medium range weather forecasts (10 days through a rainfall-runoff model to flood inundation predictions within the European Flood Forecasting System (EFFS

    Directory of Open Access Journals (Sweden)

    F. Pappenberger

    2005-01-01

    Full Text Available The political pressure on the scientific community to provide medium to long term flood forecasts has increased in the light of recent flooding events in Europe. Such demands can be met by a system consisting of three different model components (weather forecast, rainfall-runoff forecast and flood inundation forecast which are all liable to considerable uncertainty in the input, output and model parameters. Thus, an understanding of cascaded uncertainties is a necessary requirement to provide robust predictions. In this paper, 10-day ahead rainfall forecasts, consisting of one deterministic, one control and 50 ensemble forecasts, are fed into a rainfall-runoff model (LisFlood for which parameter uncertainty is represented by six different parameter sets identified through a Generalised Likelihood Uncertainty Estimation (GLUE analysis and functional hydrograph classification. The runoff of these 52 * 6 realisations form the input to a flood inundation model (LisFlood-FP which acknowledges uncertainty by utilising ten different sets of roughness coefficients identified using the same GLUE methodology. Likelihood measures for each parameter set computed on historical data are used to give uncertain predictions of flow hydrographs as well as spatial inundation extent. This analysis demonstrates that a full uncertainty analysis of such an integrated system is limited mainly by computer power as well as by how well the rainfall predictions represent potential future conditions. However, these restrictions may be overcome or lessened in the future and this paper establishes a computationally feasible methodological approach to the uncertainty cascade problem.

  2. The effect of symbiotic ant colonies on plant growth: a test using an Azteca-Cecropia system.

    Science.gov (United States)

    Oliveira, Karla N; Coley, Phyllis D; Kursar, Thomas A; Kaminski, Lucas A; Moreira, Marcelo Z; Campos, Ricardo I

    2015-01-01

    In studies of ant-plant mutualisms, the role that ants play in increasing the growth rates of their plant partners is potentially a key beneficial service. In the field, we measured the growth of Cecropia glaziovii saplings and compared individuals that were naturally colonized by Azteca muelleri ants with uncolonized plants in different seasons (wet and dry). We also measured light availability as well as attributes that could be influenced by the presence of Azteca colonies, such as herbivory, leaf nutrients (total nitrogen and δ(15)N), and investments in defense (total phenolics and leaf mass per area). We found that colonized plants grew faster than uncolonized plants and experienced a lower level of herbivory in both the wet and dry seasons. Colonized plants had higher nitrogen content than uncolonized plants, although the δ(15)N, light environment, total phenolics and leaf mass per area, did not differ between colonized and uncolonized plants. Since colonized and uncolonized plants did not differ in the direct defenses that we evaluated, yet herbivory was lower in colonized plants, we conclude that biotic defenses were the most effective protection against herbivores in our system. This result supports the hypothesis that protection provided by ants is an important factor promoting plant growth. Since C. glaziovii is widely distributed among a variety of forests and ecotones, and since we demonstrated a strong relationship with their ant partners, this system can be useful for comparative studies of ant-plant interactions in different habitats. Also, given this study was carried out near the transition to the subtropics, these results help generalize the geographic distribution of this mutualism and may shed light on the persistence of the interactions in the face of climate change.

  3. The effect of symbiotic ant colonies on plant growth: a test using an Azteca-Cecropia system.

    Directory of Open Access Journals (Sweden)

    Karla N Oliveira

    Full Text Available In studies of ant-plant mutualisms, the role that ants play in increasing the growth rates of their plant partners is potentially a key beneficial service. In the field, we measured the growth of Cecropia glaziovii saplings and compared individuals that were naturally colonized by Azteca muelleri ants with uncolonized plants in different seasons (wet and dry. We also measured light availability as well as attributes that could be influenced by the presence of Azteca colonies, such as herbivory, leaf nutrients (total nitrogen and δ(15N, and investments in defense (total phenolics and leaf mass per area. We found that colonized plants grew faster than uncolonized plants and experienced a lower level of herbivory in both the wet and dry seasons. Colonized plants had higher nitrogen content than uncolonized plants, although the δ(15N, light environment, total phenolics and leaf mass per area, did not differ between colonized and uncolonized plants. Since colonized and uncolonized plants did not differ in the direct defenses that we evaluated, yet herbivory was lower in colonized plants, we conclude that biotic defenses were the most effective protection against herbivores in our system. This result supports the hypothesis that protection provided by ants is an important factor promoting plant growth. Since C. glaziovii is widely distributed among a variety of forests and ecotones, and since we demonstrated a strong relationship with their ant partners, this system can be useful for comparative studies of ant-plant interactions in different habitats. Also, given this study was carried out near the transition to the subtropics, these results help generalize the geographic distribution of this mutualism and may shed light on the persistence of the interactions in the face of climate change.

  4. The Effect of Symbiotic Ant Colonies on Plant Growth: A Test Using an Azteca-Cecropia System

    Science.gov (United States)

    Oliveira, Karla N.; Coley, Phyllis D.; Kursar, Thomas A.; Kaminski, Lucas A.; Moreira, Marcelo Z.; Campos, Ricardo I.

    2015-01-01

    In studies of ant-plant mutualisms, the role that ants play in increasing the growth rates of their plant partners is potentially a key beneficial service. In the field, we measured the growth of Cecropia glaziovii saplings and compared individuals that were naturally colonized by Azteca muelleri ants with uncolonized plants in different seasons (wet and dry). We also measured light availability as well as attributes that could be influenced by the presence of Azteca colonies, such as herbivory, leaf nutrients (total nitrogen and δ15N), and investments in defense (total phenolics and leaf mass per area). We found that colonized plants grew faster than uncolonized plants and experienced a lower level of herbivory in both the wet and dry seasons. Colonized plants had higher nitrogen content than uncolonized plants, although the δ15N, light environment, total phenolics and leaf mass per area, did not differ between colonized and uncolonized plants. Since colonized and uncolonized plants did not differ in the direct defenses that we evaluated, yet herbivory was lower in colonized plants, we conclude that biotic defenses were the most effective protection against herbivores in our system. This result supports the hypothesis that protection provided by ants is an important factor promoting plant growth. Since C. glaziovii is widely distributed among a variety of forests and ecotones, and since we demonstrated a strong relationship with their ant partners, this system can be useful for comparative studies of ant-plant interactions in different habitats. Also, given this study was carried out near the transition to the subtropics, these results help generalize the geographic distribution of this mutualism and may shed light on the persistence of the interactions in the face of climate change. PMID:25811369

  5. Does exogenic food benefit both partners in an ant-plant mutualism? The case of Cecropia obtusa and its guest Azteca plant-ants.

    Science.gov (United States)

    Dejean, Alain; Petitclerc, Frédéric; Roux, Olivier; Orivel, Jérôme; Leroy, Céline

    2012-03-01

    In the mutualisms involving the myrmecophyte Cecropia obtusa and Azteca ovaticeps or A. alfari, both predatory, the ants defend their host trees from enemies and provide them with nutrients (myrmecotrophy). A. ovaticeps provisioned with prey and then (15)N-enriched food produced more individuals than did control colonies (not artificially provisioned). This was not true for A. alfari colonies, possibly due to differences in the degree of maturity of the colonies for the chosen range of host tree sizes (less than 3m in height). Myrmecotrophy was demonstrated for both Azteca species as provisioning the ants with (15)N-enriched food translated into higher δ(15)N values in host plant tissues, indicating that nitrogen passed from the food to the plant. Thus, the predatory activity of their guest ants benefits the Cecropia trees not only because the ants protect them from defoliators since most prey are phytophagous insects but also because the plant absorbs nutrients.

  6. First report of two species of scarab beetles (Coleoptera, Scarabaeidae inside nests of Azteca cf. chartifex Forel (Hymenoptera, Formicidae in Brazilian Amazonian Rainforest

    Directory of Open Access Journals (Sweden)

    João Rafael Alves-Oliveira

    Full Text Available ABSTRACT We report for the first time the occurrence of two species of scarab beetles, Phileurus carinatus declivis Prell, 1914 (Scarabaeidae: Dynastinae and Cyclidius elongatus (Olivier, 1789 (Cetoniinae: Cremastocheilini inside nests of Azteca cf. chartifex Forel, 1896, a neotropical arboreal ant species. This report indicates that these two beetle species are associated, at least as inquilines, to this ant species, although the nature of this relationship remains unclear.

  7. Sex-specific nutrient use and preferential allocation of resources to a sexually selected trait in Hyalella amphipods.

    Science.gov (United States)

    Goos, Jared M; Cothran, Rickey D; Jeyasingh, Punidan D

    2016-03-01

    Although sexually dimorphic traits are often well studied, we know little about sex-specific resource use strategies that should underlie such dimorphism. We measured sex-specific responses in acquisition and assimilation of two fundamental resources, carbon (C) and phosphorus (P) in juvenile and mature Hyalella amphipods given low and high supplies of inorganic phosphate, analogous to oligotrophic and eutrophic conditions, respectively. Additionally, we quantified allocation of resources to sexual traits in males. Dual radiotracer ((14)C and (33)P) assays revealed substantial age- and sex-specific differences in acquisition and assimilation. Furthermore, a phenotypic manipulation experiment revealed that amphipods fed low-P food allocated more C to all traits than those fed high-P food. Importantly, we found that amphipods preferentially allocated more C to the development of a sexually selected trait (the posterior gnathopod), compared with a serially homologous trait (the fifth pereopod) not under sexual selection. Substantial differences in how the sexes use fundamental resources, and the impact of altered nutrient supply on such differences, illuminate sexual dimorphism at the lowest level of biological organization. Such information will be important in understanding how sex- and age-specific life history demands influence nutrient processing in a biosphere characterized by rapidly changing alterations to biogeochemical cycles.

  8. Trait-based modelling of bioaccumulation by freshwater benthic invertebrates

    NARCIS (Netherlands)

    Sidney, L.A.; Diepens, N.J.; Guo, X.; Koelmans, A.A.

    2016-01-01

    Understanding the role of species traits in chemical exposure is crucial for bioaccumulation and toxicity assessment of chemicals. We measured and modelled bioaccumulation of polychlorinated biphenyls (PCBs) in Chironomus riparius, Hyalella azteca, Lumbriculus variegatus and Sphaerium corneum. We us

  9. CHRONIC EFFECTS OF THE HERBICIDE DIURON ON FRESHWATER CLADOCERANS,AMPHIPODS,MIDGES,MINNOWS,WORMS, AND SNAILS

    Science.gov (United States)

    The chronic effects of the herbicide diuron on survival and reproduction of Daphnia pulex, and survival and growth of the amphipod Hyalella azteca, the midge Chironomus tentans, juvenile and embro/larval fathead minnows, Pimephales promelas, annelid worms, Lumbriculus variegatus,...

  10. Trait-based modelling of bioaccumulation by freshwater benthic invertebrates

    NARCIS (Netherlands)

    Sidney, L.A.; Diepens, N.J.; Guo, X.; Koelmans, A.A.

    2016-01-01

    Understanding the role of species traits in chemical exposure is crucial for bioaccumulation and toxicity assessment of chemicals. We measured and modelled bioaccumulation of polychlorinated biphenyls (PCBs) in Chironomus riparius, Hyalella azteca, Lumbriculus variegatus and Sphaerium corneum. We

  11. Toxicity of major geochemical ions to freshwater species

    Science.gov (United States)

    Extensive testing regarding the toxicity of major geochemical ions to Ceriodaphnia dubia, Hyalella azteca, and Pimephales promelas will be presented. For C. dubia, tests of single salts and binary mixtures in various dilution waters demonstrated multiple mechanisms of toxicity an...

  12. Disentangling endogenous versus exogenous pattern formation in spatial ecology: a case study of the ant Azteca sericeasur in southern Mexico.

    Science.gov (United States)

    Li, Kevin; Vandermeer, John H; Perfecto, Ivette

    2016-05-01

    Spatial patterns in ecology can be described as reflective of environmental heterogeneity (exogenous), or emergent from dynamic relationships between interacting species (endogenous), but few empirical studies focus on the combination. The spatial distribution of the nests of Azteca sericeasur, a keystone tropical arboreal ant, is thought to form endogenous spatial patterns among the shade trees of a coffee plantation through self-regulating interactions with controlling agents (i.e. natural enemies). Using inhomogeneous point process models, we found evidence for both types of processes in the spatial distribution of A. sericeasur. Each year's nest distribution was determined mainly by a density-dependent relationship with the previous year's lagged nest density; but using a novel application of a Thomas cluster process to account for the effects of nest clustering, we found that nest distribution also correlated significantly with tree density in the later years of the study. This coincided with the initiation of agricultural intensification and tree felling on the coffee farm. The emergence of this significant exogenous effect, along with the changing character of the density-dependent effect of lagged nest density, provides clues to the mechanism behind a unique phenomenon observed in the plot, that of an increase in nest population despite resource limitation in nest sites. Our results have implications in coffee agroecological management, as this system provides important biocontrol ecosystem services. Further research is needed, however, to understand the effective scales at which these relationships occur.

  13. Financial effects of the corporative government and ethics in Mexico’s businesses: the case of Cemex and TV-Azteca

    OpenAIRE

    Pablo Lopez Sarabia

    2007-01-01

    Este artículo muestra que las malas prácticas de gobierno corporativo y falta de ética puede afectar el desempeño inanciero de las empresas y muy en particular su valor de mercado. Se analiza a TV-Azteca que enfrenta una demanda de fraude por una recompra de deuda violando la regulación del mercado bursátil de Estados Unidos de América en especial la Ley Sarbanes-Oxley, los resultados econométricos muestran que el valor de la empresa y el precio han disminuido a partir del inicio de investiga...

  14. In Situ Estuarine and Marine Toxicity Testing: A Review, Including Recommendations for Future Use in Ecological Risk Assessment

    Science.gov (United States)

    2009-09-01

    39 Lavoie et al. (2001) used the freshwater amphipod Hyallela azteca , as well as the cladoceran Daphnia magna, in caged exposures as part of an...54 pp., June 2003. Chappie DJ and Burton GA, Jr., 1997. Optimization of in situ bioassays with Hyalella azteca and Chironomus tentans. Environ

  15. Environmental and habitat drivers of relative abundance for a suite of azteca-attacking Pseudacteon phorid flies.

    Science.gov (United States)

    Reese, Katlynd M; Philpott, Stacy M

    2012-10-01

    Phoridae (Diptera) have widespread impacts on insect communities by limiting host ant behavior. However, phorid-ant interactions may vary with habitat or environmental conditions. Three Pseudacteon species parasitize Azteca instabilis Fr. Smith, a common ant in coffee agroecosystems, and limit A. instabilis foraging, indirectly benefiting other insects. However, little is known about how phorid abundance, behavior, and effects change with environmental conditions. In shaded coffee systems, coffee (Coffea arabica L.) grows under a range of shade conditions and management changes affect species interactions. For example, Pseudacteon spp. more strongly limit A. instabilis foraging in low-shade coffee habitats. We sampled relative abundance of three phorid species around A. instabilis nests in three coffee habitats varying in shade management during dry and wet seasons. We measured canopy cover, tree richness, tree density, leaf litter depth, and number of nearby trees with A. instabilis to determine whether these habitat factors correlate with phorid abundance. P. laciniosus Brown was the most abundant phorid in both seasons. Phorid relative abundance did not differ by habitat, but did differ by season. P. laciniosus accounted for a higher proportion of phorids in the wet season (91.4%) than in the dry season (78.9%), and P. planidorsalis Brown accounted for a larger percent in the dry season (21.1%) than in the wet season (7.3%). Phorid composition did not differ with habitat type, and none of the measured environmental variables correlated with changes in phorid composition. Thus, phorids in coffee agroecosystems respond to large seasonal differences, but not differences between coffee habitats.

  16. Hypothenemus hampei (Coleoptera: Curculionidae) and its interactions with Azteca instabilis and Pheidole synanthropica (Hymenoptera: Formicidae) in a shade coffee agroecosystem.

    Science.gov (United States)

    Jiménez-Soto, Estelí; Cruz-Rodríguez, Juan A; Vandermeer, John; Perfecto, Ivette

    2013-10-01

    The coffee berry borer is currently the most important insect pest of coffee worldwide. In shaded coffee farms such as Finca Irlanda in Chiapas, Mexico, natural enemies limit coffee berry borer and potentially prevent outbreaks. This research aimed to determine the effect of ants on coffee berry borer damage and to describe behaviors of Azteca instabilis F. Smith and Pheidole synanthropica (Longino 2009) when encountering the coffee berry borer. To these ends, an ant survey was conducted in a 2,500-m(2) plot within the farm. A 4- by 4-m coordinate system was established, and the coffee plant or shade tree closest to the coordinate point was sampled using tuna fish for a total of 168 coffee plants and 46 shade trees sampled. In addition, up to 100 berries were harvested from 138 coffee plants to measure damage and verify the presence of the coffee berry borer. Behavior was determined in the field by placing live coffee berry borer adults on berries and video recording all attacks. Results showed that plants with ants had less percentage of damaged berries and shorter coffee berry borer galleries than plants without ants. However, the length of galleries in plants with A. instabilis showed no significant differences from plants without ants. P. synanthropica was observed carrying coffee berry borer to the nest in 50% of the cases, whereas A. instabilis threw coffee berry borer off of the coffee plant in 79% of the cases. Results indicate that the presence of these species of ants reduce coffee berry borer damage and suggest that different behaviors could explain the pattern of coffee berry borer attack in this agroecosystem.

  17. Demonstration and Certification of Amphibian Ecological Risk Assessment Protocol. Cost and Performance Report (Version 2)

    Science.gov (United States)

    2009-07-01

    day benthic invertebrate toxicity tests conducted with the midge, Chironomus tentans, and the amphipod, Hyalella azteca . Actual unit costs for these...management decisions in wetlands often rely on site-specific benthic invertebrate toxicity testing using organisms such as the amphipod, H. azteca ...amphipod (H. azteca ), and the fathead minnow (Pimephales promelas). Although remediation has not yet occurred, the arsenic NOAEC from the amphibian

  18. Indirect interactions between ant-tended hemipterans, a dominant ant Azteca instabilis (Hymenoptera: Formicidae), and shade trees in a tropical agroecosystem.

    Science.gov (United States)

    Livingston, George F; White, Adam M; Kratz, Carley J

    2008-06-01

    The occurrence, intensity, and composition of mutualisms are dependent not only on the co-occurrence of mutualists, but also the broader biotic context in which they are embedded. Here, the influence of the specific nest tree identity of the ant Azteca instabilis (F. Smith) on the density of the green coffee scale (Coccus viridis Green) was studied in a coffee agroecosystem in southern Mexico. The hypothesis that an indirect competitive interaction for ant attendance occurs between a scale species (Octolecanium sp. Kondo) in the canopy of the shade tree Inga micheliana Harms and C. viridis, which inhabits coffee bushes (Coffea arabica) beneath the shade trees was tested. Coffee bushes beneath a different shade tree species (Alchornea latifolia Swartz) were used as an indication of C. viridis density in a noncompetitive environment. Results indicate that C. viridis occurs in significantly lower density adjacent to nests in Inga, supporting the hypothesis of indirect competition. Additional experimentation suggests that there is a mutualism between Azteca and Octolecanium and that this interaction may be mediated by a hierarchy in ant attendance of scale insects. Our results show the importance of considering the biotic context of ant-hemipteran mutualisms. In coffee agroecosystems, consideration of shade tree diversity and species composition may be directly applicable to the biological control of insect pests.

  19. Effects of a 10-Day Intensive Health Promotion Program Combining Diet and Physical Activity on Body Composition, Physical Fitness, and Blood Factors of Young Adults: A Randomized Pilot Study.

    Science.gov (United States)

    Lee, Kyoung Soon; Lee, Jae Koo; Yeun, Young Ran

    2017-04-11

    BACKGROUND A lifestyle characterized by poor eating habits and physical inactivity is a risk factor for multiple lifestyle diseases in young adults. This study assessed the effects of implementing an intensive 10-day health promotion program combining diet and physical activities on body composition, physical fitness, and biochemical parameters of young adults. MATERIAL AND METHODS In this randomized pilot study, 30 female undergraduate students were randomly allocated to an intervention and a control group. The health promotion program consisted of unlimited amounts of vegetarian food; aerobic, flexibility, and strength exercises (3 hours/day); lectures on health (3 hours/day); massage practice (2 hours/day); and healthy cooking practice (1 hour/day). The effects of the intervention were analyzed using the Mann-Whitney U test and the Wilcoxon signed-rank test. RESULTS The intensive 10-day health promotion program significantly reduced body weight, body mass index, triglyceride, total cholesterol, low-density lipoprotein cholesterol, blood glucose, and the homeostasis model assessment of insulin resistance. At the same time, participants demonstrated increased back muscle, leg muscle, and grip strength; waist and shoulder flexibility; balance; and cardiorespiratory endurance. CONCLUSIONS The intensive 10-day health promotion program is a viable intervention for improving body composition, physical fitness, glycemic control, and blood lipid levels in young adults.

  20. Spatial patterns of Pisidium chilense (Mollusca Bivalvia and Hyalella patagonica (Crustacea, Amphipoda in an unpolluted stream in Navarino island (54° S, Cape Horn Biosphere Reserve

    Directory of Open Access Journals (Sweden)

    Patricio De Los Ríos Escalante

    2017-01-01

    Full Text Available The southern South American inland waters have many endemic species and some of them are considered as endangered for IUCN, that inhabits in unpolluted ecosystems, one of these ecosystems are the sub-Antarctic perennial forests located in the Cape Horn Biosphere Reserve at 54° S. The aim of the present study is to analyze the spatial patterns of Pisidium chilense Ituarte, 1999 (Mollusca Bivalvia and Hyalella patagonica (Cunningham, 1871 (Crustacea, Amphipoda in an unpolluted stream. Both species had aggregated spatial distribution, both have a negative binomial distribution pattern, and both are associated. The present results would agree with similar patterns in Patagonian rivers where both species coexist.

  1. Clinical observation of 10-days sequential treatment to eradicate helicobacter pylori%10日序贯疗法根除幽门螺杆菌的临床观察

    Institute of Scientific and Technical Information of China (English)

    黄玉凯; 周进; 徐斌

    2010-01-01

    目的 比较10日序贯疗法与传统三联疗法根除幽门螺杆菌(Hp)的疗效.方法 选取14C尿素呼气试验阳性或者胃镜活组织检查Hp阳性病例90例,随机分为两组:治疗组前5 d予雷贝拉唑、阿莫西林,后5 d予雷贝拉唑、替硝唑、左氧氟沙星治疗;对照组予雷贝拉唑、阿莫西林、克拉霉素(三联疗法)治疗10 d.疗程结束1月后行14C尿素呼气试验检测.结果 治疗组Hp根除率为93.3%,对照组根除率为75.6%,两组Hp根除率差异有统计学意义(P<0.05).结论 与传统三联疗法比较,以雷贝拉唑、左氧氟沙星等组成的10日序贯疗法治疗Hp感染具有较高的根除率.%Objective To compare the efficacy of 10-days sequential treatment( including rabeprazole,amoxillin, levofloxacin and tinidazole) and traditional trigeminy therapy (including rabeprazole, amoxillin and clarithromy-cin) for the eradication of helicobacter pylori ( Hp). Methods 90 patients with Hp positive who were detected by 14C urea breath test or gastroscope Hp test were randomly divided into two groups: the therapeutic group and the control group. The therapeutic group was treated with rabeprazole,amoxillin at first 5 days,rabeprazole,levofloxacin and tinidazole at the second 5 days,while the control group was treated with rabeprazole,amoxillin and clarithromycin for 10 days. The 14C urea breath test was detected after course of treatment finished in a month. Results The eradication rate of 10 days sequential treatment was 93. 3% and that of control group was 75. 6% ,and the difference between two groups was significant(P <0.05). Conclusion Comparing with traditional trigeminy therapy,the 10-days sequential treatment comprising rabeprazole and levofloxacin could achieve a higher eradication rate of Hp.

  2. Prednisone 10 days on/10 days off in patients with Duchenne muscular dystrophy.

    NARCIS (Netherlands)

    Straathof, C.S.; Overweg-Plandsoen, W.C.; Burg, G.J. van den; Kooi, A.J. van der; Verschuuren, J.J.; Groot, I.J.M. de

    2009-01-01

    Corticosteroids are effective in improving motor function in Duchenne muscular dystrophy (DMD) patients within 6 months-2 years of treatment initiation, but there is as yet no consensus on which treatment scheme is the best. We retrospectively analyzed data of 35 DMD patients who were treated with p

  3. 励珂健喷剂对10日龄内仔猪腹泻和免疫力的影响%Effects of Likejian Spray on the Piglet Diarrhea and Immunity within 10 Days Ag

    Institute of Scientific and Technical Information of China (English)

    臧猛; 郑声陶; 谢坤

    2014-01-01

    In order to research the effects of piglet diarrhea and immunity caused by Likejian Spray(main ingredi-ents:Flos Populi extract ) within 10 days of age,18 PIC sows were divided into three groups, distilled water group、terramycin group and Likejian group, six sows each group. 1 mL distilled water each day was sprayed at 1、3、5 days of age for distilled water group, 0.2 mL and 0.5 mL 20%Long-acting terramycin injection each day was in-jected into the muscle at 3、7 days of age for terramycin group, 1 mL Likejian Spray each day was sprayed in 1、3、5 days of age for Likejian group. The results showed that the diarrhea rate and the morbidity within 10 days of age were reduced effectively by Likejian Spray,and the cure speed of the diarrhea piglets in Likejian group was faster than that of terramycin group and distilled water group. So it was proved that Likejian Spray could prevent and cure the piglet diarrhea within 10 days of age, and could strengthen immunity as well.%为研究励珂健喷剂(主要成分:杨树花提取物)对10日龄内仔猪腹泻和免疫力的影响,将18头PIC母猪随机分成3组,每组6头,分别为蒸馏水组、土霉素组和励珂健喷剂组,蒸馏水组仔猪1、3、5日龄时皮肤喷洒蒸馏水1 mL/头/d,土霉素组仔猪3、7日龄时分别肌肉注射20%长效土霉素注射液0.2 mL/头/d、0.5 mL/头/d,励珂健喷剂组仔猪1、3、5日龄时皮肤喷洒励珂健喷剂1 mL/头/d。结果表明,励珂健喷剂可有效降低10日龄内仔猪的腹泻率和发病率,且励珂健喷剂组腹泻仔猪的治愈速度快于土霉素组和蒸馏水组。由此证明:励珂健喷剂对10日龄内仔猪腹泻有防治作用,并且还可以增强仔猪的免疫力。

  4. [Antibiotic therapy against acute tonsillopharyngitis in children due to group A beta-hemolytic streptococci: comparison of clinical efficacy, the bactericidal effects, and effects on oral flora between cefditoren pivoxil for 5 days and amoxicillin for 10 days].

    Science.gov (United States)

    Tsumura, Naoki; Nagai, Kensuke; Hidaka, Hidenobu; Otsu, Yasushi; Tanaka, Yuhei; Ikezawa, Shigeru; Honma, Shinichi; Shindo, Shizuo; Ubukata, Kimiko

    2011-06-01

    We compared the clinical efficacy, the bactericidal effects, effect on the oral microbial flora, and adverse reactions between cefditoren pivoxil (CDTR-PI) for 5 days and amoxicillin (AMPC) for 10 days in children with acute group A beta-hemolytic streptococci (GAS) tonsillopharyngitis, and simultaneously examined the emm genotype and drug susceptibility of the isolated GAS. The results showed that the clinical efficacy was 100% for CDTR-PI and 97.9% for AMPC, with no difference between the two groups, and the bacterial elimination rate was 100% in both groups. No serious adverse event was noted in either group. On the other hand, concerning changes in the oral microbial flora between before and after treatment, the amount of bacteria showed no change in the CDTR-PI group (p = 0.5761) but clearly decreased in the AMPC group (p = 0.0049). This indicates that CDTR-PI does not disturb the oral microbial flora compared with AMPC. Also, the emm types determined in the 112 GAS strains isolated in this study were similar to those that have recently been isolated frequently in Japan. Concerning the drug resistance, none of the isolates showed resistance to beta-lactam antibiotics, but 45% of them were resistant to macrolides. The advantages of short-term treatment are considered to include a lower cost, improvement in drug compliance, decrease in the frequency of the occurrence of adverse reactions, decrease in the frequency of the appearance of drug-resistant strains, and alleviation of the psychological burden of patients and their parents. For these reasons, we conclude that CDTR-PI for 5 days is a useful option for the treatment of acute GAS tonsillopharyngitis in children.

  5. Interação planta-inseto: Aspectos biológicos e ecológicos do mutualismo Cecropia-Azteca

    Directory of Open Access Journals (Sweden)

    2015-08-01

    Abstract. A well-known association is the mutualism between plants is between plant species of the genus Cecropia and ants, mostly belonging to the genus Azteca. In this association, the ants nest in domatia present in the hollow trunk of this myrmecophytes and feed on food bodies provided by the plant, known as mullerian bodies. In return, the ants protect the host plant against herbivore attacks and invasion by vines, and nourish it through waste laid in the trunk. However, the effectiveness of this association may vary with several factors, such as the associated ant species and the habitat type of the myrmecophyte. About 10% of Cecropia species lost their attractive characteristics, such as species living in high altitude and inhabit islands. Aspects like associated ant richness and molecular studies show that the colonization of these plants by ants occurred several times and independently by different genera. The selection pressure exerted by some species of ants may have been one of the decisive factors for the development of attractive traits for ants in Cecropia. With the evolution of these features ants might become an effective partner of the plant, facilitating the co-evolution of specific interactions.

  6. Efectos financieros del gobierno corporativo y ética en los negocios en México: el caso de Cemex y TV-Azteca

    Directory of Open Access Journals (Sweden)

    Pablo Lopez Sarabia

    2007-12-01

    Full Text Available Este artículo muestra que las malas prácticas de gobierno corporativo y falta de ética puede afectar el desempeño inanciero de las empresas y muy en particular su valor de mercado. Se analiza a TV-Azteca que enfrenta una demanda de fraude por una recompra de deuda violando la regulación del mercado bursátil de Estados Unidos de América en especial la Ley Sarbanes-Oxley, los resultados econométricos muestran que el valor de la empresa y el precio han disminuido a partir del inicio de investigación de la Securities and Exchange Commission (SEC. Por lo que se reiere a Cementos Mexicanos (Cemex es una empresa que ha desarrollado un código de ética interno y ajustado al Código de Mejores Prácticas Corporativas, así como un impulsor entusiasta de las buenas prácticas de gobierno corporativo.

  7. Primary sources and toxicity of PAHs in Milwaukee-area streambed sediment

    Science.gov (United States)

    Baldwin, Austin K.; Corsi, Steven R.; Lutz, Michelle A.; Ingersoll, Christopher G.; Dorman, Rebecca A.; Magruder, Christopher; Magruder, Matthew

    2016-01-01

    High concentrations of polycyclic aromatic hydrocarbons (PAHs) in streams can be a significant stressor to aquatic organisms. To understand the likely sources and toxicity of PAHs in Milwaukee-area streams, streambed sediment samples from 40 sites and parking lot dust samples from 6 sites were analyzed for 38 parent PAHs and 25 alkylated PAHs. Diagnostic ratios, profile correlations, principal components analysis, source-receptor modeling, and mass fractions analysis were used to identify potential PAH sources to streambed sediment samples, and land-use analysis was used to relate streambed sediment PAH concentrations to different urban-related land uses. On the basis of this multiple lines-of-evidence approach, coal-tar pavement sealant was indicated as the primary source of PAHs in a majority of streambed sediment samples, contributing an estimated 77% of total PAHs to samples, on average. Comparison to the Probable Effect Concentrations and (or) the Equilibrium Partitioning Sediment Benchmark indicates that 78% of stream sediment samples are likely to cause adverse effects to benthic organisms. Laboratory toxicity tests on a 16-sample subset of the streambed sites using the amphipod Hyalella azteca (28-day) and the midge Chironomus dilutus (10-day) measured significant reductions in one or more biological endpoints, including survival, in 75% of samples, with H. azteca more responsive than C. dilutus.

  8. La participación de Televisa y TV Azteca en la construcción, promoción de imagen y percepción ciudadana, de candidatos y gobernantes mexicanos con financiamiento público

    OpenAIRE

    Orta Vélez, Juan Miguel

    2010-01-01

    En México, gobernantes y candidatos, han aplicado innovadoras formas de promover su imagen, la principal herramienta la constituye el duopolio: Televisa y TV Azteca. Inicialmente las campañas políticas en televisión, consistían en la compra de spots y cobertura en noticieros, es a partir del año 2000, cuando políticos y gobiernos en contubernio con las televisoras, irrumpen esta práctica mediante programas de entretenimiento, deportes, espectáculos, incluso comedia, tomando por sorpresa al te...

  9. La participación de Televisa y TV Azteca en la construcción, promoción de imagen y percepción ciudadana, de candidatos y gobernantes mexicanos con financiamiento público

    OpenAIRE

    Orta Vélez, Juan Miguel

    2010-01-01

    En México, gobernantes y candidatos, han aplicado innovadoras formas de promover su imagen, la principal herramienta la constituye el duopolio: Televisa y TV Azteca. Inicialmente las campañas políticas en televisión, consistían en la compra de spots y cobertura en noticieros, es a partir del año 2000, cuando políticos y gobiernos en contubernio con las televisoras, irrumpen esta práctica mediante programas de entretenimiento, deportes, espectáculos, incluso comedia, tomando por sorpresa al te...

  10. The Toxicity of Nitroguanidine and Photolyzed Nitroguandine to Freshwater Aquatic Organisms

    Science.gov (United States)

    1985-03-01

    teema R0.t) - 33ICY WORDfl1’CAtttewe amee~A ejolft~l ofc.. "**eef andatIA"b 5 Welt ftwaeo)•ute tox city • mannel cattish1,H allela azteca • ’Midge...of well water for transfer to the test chambers. One amphipod used ii testing was _Hyalella azteca , which was collected from Hunt’s Pvnd nedr Norwich...NY. H. azteca was keyed to species using Pennak. 12 The other amphipod tested was Gammarus minus, which was obtained from a spring in the Frederick M

  11. La psicología mesoamericana: ideas psicológicas, psicopatológicas y psicoterapéuticas en las culturas maya, purépecha y azteca

    OpenAIRE

    Pavón-Cuéllar, David

    2013-01-01

    El presente artículo ofrece una visión panorámica de las ideas psicológicas en las culturas mesoamericanas, particularmente en la época prehispánica, pero también en siglos posteriores. Se presta especial atención a las psicologías maya, purépecha y azteca. La psicología maya despliega sus clasificaciones psicopatológicas, sus técnicas terapéuticas y sus representaciones de la vinculación entre el alma y el cuerpo. Esta vinculación es profundizada en una psicología purépecha esencialmente soc...

  12. Phototoxicity of TiO2 nanoparticles to a freshwater benthic amphipod: are benthic systems at risk?

    Science.gov (United States)

    This study investigated phototoxicity of TiO2 nanoparticles (nano-TiO2) to a freshwater benthic amphipod (Hyalella azteca) using 48-h and 96-h bioassays. Thorough monitoring of particle interactions with exposure media (Lake Superior water, LSW) and the surface of organisms was p...

  13. Toxicity evaluation of a conservation effects assessment program watershed, Beasley Lake, in the Mississippi Delta, USA

    Science.gov (United States)

    Beasley Lake was assessed monthly in 2005 for biological impairment from 17 historic and current-use pesticides in water and leaf litter using Hyalella azteca (Saussure). Sixteen pesticides were detected in both water and leaf litter with peak detections in spring and summer. Detections ranged fro...

  14. 60th anniversary celebrations: events in the coming 10 days

    CERN Multimedia

    2014-01-01

    This is an eventful week. Read this summary and don’t miss these unique events!   Saturday 20 September: Particle Fever film screening and Comedy Night show: the event is sold out but the discussion that will take place between 8.45 p.m. and 9.30 p.m. will be available on webcast. Thursday 25 and Friday 26 September: Researchers' Night - POPscience. To make the Researchers' Night even more POPular, CERN will meet its public outside the Laboratory: at FNAC Rive, the Salle Centrale Madeleine (free entrance, reservation possible), and the Théâtre du Bordeau in Saint-Genis-Pouilly. A unique mix of arts, poetry, theatre, music, science and encounters. Friday 26 September: From Physics to daily life colloquium in the Main Auditorium will feature talks by several scientists and experts of the technologies that have changed our life. The webcast in English and French will be available from 9 a.m. Monday 29 ...

  15. Enhancing Resilience in Youth through a 10-Day Developmental Voyage

    Science.gov (United States)

    Hayhurst, Jill; Hunter, John A.; Kafka, Sarah; Boyes, Mike

    2015-01-01

    The present study sought to examine the potential for resilience to be enhanced in a group of youth participating in a developmental voyage, and to identify the factors that contribute to increased resilience following the voyage. Two studies are reported. Study 1 revealed that voyage participants experienced increased resilience over the course…

  16. Enhancing Resilience in Youth through a 10-Day Developmental Voyage

    Science.gov (United States)

    Hayhurst, Jill; Hunter, John A.; Kafka, Sarah; Boyes, Mike

    2015-01-01

    The present study sought to examine the potential for resilience to be enhanced in a group of youth participating in a developmental voyage, and to identify the factors that contribute to increased resilience following the voyage. Two studies are reported. Study 1 revealed that voyage participants experienced increased resilience over the course…

  17. Toxicity of fluoride to aquatic species and evaluation of toxicity modifying factors.

    Science.gov (United States)

    Pearcy, Krysta; Elphick, James; Burnett-Seidel, Charlene

    2015-07-01

    The present study was performed to investigate the toxicity of fluoride to a variety of freshwater aquatic organisms and to establish whether water quality variables contribute substantively to modifying its toxicity. Water hardness, chloride, and alkalinity were tested as possible toxicity modifying factors for fluoride using acute toxicity tests with Hyalella azteca and Oncorhynchus mykiss. Chloride appeared to be the major toxicity modifying factor for fluoride in these acute toxicity tests. The chronic toxicity of fluoride was evaluated with a variety of species, including 3 fish (Pimephales promelas, O. mykiss, and Salvelinus namaycush), 3 invertebrates (Ceriodaphnia dubia, H. azteca, and Chironomus dilutus), 1 plant (Lemna minor), and 1 alga (Pseudokirchneriella subcapitata). Hyalella azteca was the most sensitive species overall, and O. mykiss was the most sensitive species of fish. The role of chloride as a toxicity modifying factor was inconsistent between species in the chronic toxicity tests.

  18. Nidificação de Polybia rejecta (Fabricius (Hymenoptera: Vespidae Associada à Azteca chartifex Forel (Hymenoptera: Formicidae em Ecótono de Bioma Caatinga/Mata Atlântica, no Estado do Rio Grande do Norte

    Directory of Open Access Journals (Sweden)

    Francisco Virgínio

    2015-12-01

    Abstract. Some neotropical social wasps which are associated with some vertebrates and other insects like ants, and these interactions are reported for decades, but little is known about the presence of these in the Caatinga and Atlantic Forest. This study describes the first association's record between nests of Polybia rejecta (Fabricius wasp and Azteca chartifex Forel ants in the transition area of the Atlantic Forest and Caatinga in Rio Grande do Norte. The observations were in a private forest in Monte Alegre, from October 2009 to September 2014 through active search for colonies, use of ad libitum method, photography and collection of specimens with traceability. In the study area were found four active colonies and one abandoned of P. rejecta, all associated with nests of A. chartifex with approach of 20-30 cm. It was found that when the colony of P. rejecta was disturbed, they became aggressive towards the disturbance object, whereas the ants gathered in order to fend off a potential predators. These interactions appear to benefit wasps and ants, it is assumed that is possible that wasps attack ants's predators, whereas the ants attack the wasps's predators. This study corroborates the hypothesis that the association between the social wasps P. rejecta and A. chartifex ants is beneficial for both species, and probably the wasps are the most benefited, but also shows the non-exclusivity of this association for the biomes up then reported.

  19. Intra-aortic balloon pumping in myocardial infarction patients with cardiogenic shock and long-term (≧ 10 days) treatment of research%主动脉内球囊反搏术在心肌梗塞并心源性休克长期(≥10d)应用治疗方面的研究

    Institute of Scientific and Technical Information of China (English)

    余天浩; 李瑜辉; 黄丹华

    2012-01-01

    [目的]主动脉内球囊反搏术被广泛应用于治疗心肌梗塞并心源性休克,然而,使用主动脉内球囊反搏术的安全期及其长期应用可能引起的并发症目前仍未能确定,本研究主要是观察需长期(≥10 d)应用主动脉内球囊反搏术治疗的患者,并预计他们的预后.[方法]88例患者应用主动脉内球囊反搏术治疗,其中41例患者应用长期(≥10 d)主动脉内球囊反搏术治疗,对比长期(≥10 d)治疗患者和常规治疗患者的治疗效果.[结果]IABP长期治疗组(≥10 d)和常规治疗组治疗前除血氧外各项指标均不存在显著差异,治疗后6h、24 h、72 h的心率、收缩压、舒张压、呼吸、血氧均不存在显著差异(P>0.05);相对于治疗前,患者在IABP治疗后6h收缩压、血氧均明显改善(P<0.05),IABP治疗后24 h、72 h心率、呼吸、血氧、收缩压均明显改善(P<0.05);相对于治疗前,患者的平均动脉压、心脏指数、主动脉内舒张压均有提高(P< 0.01);多变量对数回归模型分析提示IABP长期(≥10 d)治疗不影响患者的死亡率;IABP治疗和呼吸支持时间与PCI治疗时间的相关分析提示,越早进行PCI治疗,则应用IABP治疗和呼吸支持时间越短.[结论]主动脉内球囊反搏术的长期(≥10d)应用不影响生存率,是可行和安全的.%[Objective]To observe long-term (≧ 10 days) application of intra-aortic balloon pump in the treatment for patients and predict their prognosis.The intra-aortic balloon pump was used to treat myocardial infarction patients and cardiogenic shock,however,the safe period of intra-aortic balloon pump operation and the complications caused by long-term application were not yet to be determined.[Methods]A total of 88 patients including 71 males,17females,were applied with intra-aortic balloon pump for treatment.Among them,41 patients in the use of long-term (≧10 days) application of intra-aortic balloon pump for treatment.All samples

  20. Biological Assessment of Upper Mississippi River Sediments.

    Science.gov (United States)

    1980-12-01

    clams Amblema plicata as solid phase test species; EL personnel added the amphipod Hyallela azteca .) It was agreed that water fleas Daphnia sp. would be...survival of freshwater amphipods H. azteca in all four of the UMR sediments was determined. Test containers were crystallizing dishes placed in a water...vidual H. azteca were placed in each test container and survival was determined after 10 days exposure. 14. Two acute toxicity experiments with water

  1. Curative effect analysis of 10 days sequential therapy and quadruple therapy in treatment of helicobacter pylori infection%10日序贯疗法与四联疗法治疗幽门螺杆菌感染疗效对比分析

    Institute of Scientific and Technical Information of China (English)

    王宏彦; 徐宝宏; 吴海波

    2013-01-01

    目的探讨10日序贯疗法与四联疗法治疗幽门螺杆菌感染疗效对比。方法随机选择对照组42例,采用四联疗法进行治疗:阿莫西林1000mg+克拉霉素500mg+奥美拉唑20mg+枸橼酸铋钾220mg,Bid,治疗10d;治疗组43例,应用10日序贯疗法治疗:前5d给予阿莫西林1000mg+奥美拉唑20mg,Bid;后5d给予甲硝唑400mg+克拉霉素500mg+奥美拉唑20mg,Bid。结果两组经10d治疗后,停PPI及抗生素满4周,经13C-UBT试验阴性者为幽门螺杆菌(H.pylori)根治成功。实验结果显示:对照组根治成功33例,根除率达78.6%(33/42);治疗组根治成功40例,根除率达93.0%(40/43)。应用统计学分析,两组比较差异具有统计学意义(P<0.05)。结论本实验结果显示,两组治疗方法对治疗幽门螺杆菌感染均有效,同比治疗组疗效更佳,具有重要的临床意义。%Objective To investigate the curative effect comparison of 10 days sequential therapy and quadruple therapy in treatment of helicobacter pylori infection. Methods 42 cases of helicobacter pylori infection were randomly selected as control group,and were given quadruple therapy:1000mg amoxicillin + 500mg clarithromycin+ 20mg omeprazole + 220mg bismuth potassium citrate, Bid, for 10 days; 43 cases of helicobacter pylori infection were randomly selected as treatment group, and were given 10 days sequential therapy:1000mg amoxicillin+20mg omeprazole for the first 5 days,Bid,and 400mg metronidazole+500mg clarithromycin+omeprazole 20 mg for the next 5 days,Bid. Results After treatment for 10 days, stop PPI and antibiotics for 4 weeks, negative 13C-UBT test means helicobacter pylori (H.p ylori) was cured successfully. Experiment results showed that 33 cases of the control group were cured successfully, eradication rate was 78.6%(33/42);40 cases of the treatment group were cured successfully, eradication rate was 93.0% (40/43). Differences of two groups was

  2. An automated overlying water-renewal system for sediment toxicity studies

    Energy Technology Data Exchange (ETDEWEB)

    Rand, G.M.; Wheat, J.V.; Carriger, J.F.; Lee, T.A

    2003-04-01

    A new system is described for sediment toxicity testing. - An automated water-renewal toxicity test system is described for exposing benthic invertebrates to whole sediments. The system will intermittently deliver laboratory or on-site water for overlying water replacement in sediment exposures. A range of cycle rates can be used to produce different volume additions of overlying water per day to exposure chambers. The system can be used with six different treatments and eight replicates per treatment producing 48 exposure chambers. Three formulated sediments with variable organic carbon (1.5%, 7.5%) and sand (14%, 63%) content were prepared to test the system exposing amphipods, Hyalella azteca and midges, Chironomus tentans in 10 day whole sediment tests. Intermittent water flow was used with a 90 min cycle time to create two volume additions of laboratory water per 24 h in exposure chambers (180 ml sediment, 320 ml water). Overlying water quality conditions, and survival and growth of both species were consistent and within acceptable limits for the testing requirements of the U.S. EPA guidelines for sediments with freshwater invertebrates.

  3. Assessing the status of sediment toxicity and macroinvertebrate communities in the Eighteenmile Creek Area of Concern, New York

    Science.gov (United States)

    George, Scott D.; Duffy, Brian T.; Baldigo, Barry P.

    2017-01-01

    In 1972, the governments of Canada and the United States committed to restoring the physical, chemical, and biological integrity of the Laurentian Great Lakes under the Great Lakes Water Quality Agreement. Through this framework, the downstream-most section of Eighteenmile Creek, a tributary to the south shore of Lake Ontario in New York, was designated as an Area of Concern (AOC) because water quality and bed sediments were contaminated by past industrial and municipal discharges, waste disposal, and pesticide usage. Five beneficial use impairments (BUIs) have been identified in the AOC including the degradation of the “benthos”, or the benthic macroinvertebrate community. This investigation used sediment toxicity testing and macroinvertebrate community assessments to determine if the toxicity of bed sediments in the AOC differed from that of an unimpacted reference stream. Results from 10-day toxicity tests indicated that survival and growth of the dipteran Chironomus dilutus and the amphipod Hyalella azteca did not differ significantly between sediments from the AOC and reference area. Analyses of benthic macroinvertebrate community integrity and structure also indicated that macroinvertebrate communities, while impacted across most sites on both streams, were generally similar between the AOC and reference area. Despite these findings, the upstream-most AOC site consistently scored poorly in all analyses, which suggests that localized sediment toxicity may exist in the AOC, even if large scale differences between the AOC and a comparable reference stream are minimal.

  4. Sediment toxicity screening with cost-effective microbiotests and conventional assays: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Vanciheluwe, M.L.; Janssen, C.R.; Persoone, G. [Univ. of Ghent (Belgium). Lab. for Biological Research in Aquatic Pollution

    1995-12-31

    A large monitoring study of freshwater sediments, using the TRIAD approach, was conducted in Flanders (Belgium). This paper reports on the results of the toxicity assessment of 80 sediment samples evaluated with a battery of microbiotests and conventional assays. Sediment pore waters, extracted by squeezing, were tested with the Microtox{reg_sign} (Vibrio fischerii) and Thamnotoxkit{trademark} F (Thamnocephalus platyurus) microbiotests and the conventional (acute) assays with algae (Selenastrum capricornutum) and daphnids (Daphnia magna). A newly developed 5 day ELS test with the catfish Clarias gariepinus was also applied to the pore waters. Solid-phase testing was performed with the Microtox Sp{reg_sign} assay and the 10 day tests with Chironomus riparius and Hyalella azteca. Uni- and multivariate statistical techniques were applied to the data matrix to select a minimal test battery from the water phase and solid phase assays and from all tests combined. The influence of sediment associated confounding factors on the validity of the test results obtained with the various assays will be discussed. Finally a comparison of the predictive power of the selected battery of signal tests and that of the complete battery will be made and the potential use of the minimal battery for the initial hazard assessment of contaminated sediments will be reviewed.

  5. Fluconazole prophylaxis for fungal infection in high risk preterm infants receiving broad-spectrum antibiotics over 10 days%氟康唑预防高危因素早产儿广谱抗生素使用后真菌感染的效果及安全性

    Institute of Scientific and Technical Information of China (English)

    陈涵强; 杨文庆; 杨长仪

    2010-01-01

    Objective To evaluate the benefits of fluconazole prophylaxis in preventing fungal infection in high risk premature infants using broad-spectrum antibiotics consecutively more than 10 days. Methods From October 2007 to September 2009, 164 preterm infants in high risk of fungal infection using broad-spectrum antibiotics consecutively more than 10 days were eligible for the study. Eighty-five infants,hospitalized from October 2008 to September 2009, were in the fluconazole group and were administered intravenously 3 mg/kg fluconazole every day for three days since the 11th day of antibiotic course. The other 79 infants, hospitalized from October 2007 to September 2008, were in the control group with no fluconazole administration. Fungal infection and colonizations and common complications were observed in the two groups. Results Fungal infection occured in six infants in the control group and none in the fluconazole group(χ2 = 4. 719,P = 0.03). There were no significant differences between the two groups in fungal colonization(χ2 =0. 175,P = 0. 675). No adverse effects of fluconazole therapy were documented. Conclusions Fluconazole prophylaxis may reduce the risk for fungal infection in high risk preterm infants.%目的 评估氟康唑对连续使用广谱抗生素10 d以上,且具有高危因素的早产儿发生侵袭性真菌感染的预防作用.方法 以2007年10月至2009年9月间入院,具有真菌感染高危因素并连续使用广谱抗生素10 d以上的164例早产儿为研究对象,将2008年10月至2009年9月入院的符合条件的85例早产儿作为预防组.予氟康唑3 mg/(kg·次)静脉滴注,每天1次,连续用3 d;将2007年10月至2008年9月入院的符合条件的79例早产儿作为对照组,不应用氟康唑预防.观察两组真菌感染和定植情况,以及常见并发症.结果 预防组无一例发生侵袭性真菌感染,对照组发生6例深部真菌感染,差异有统计学意义(χ2=4.719,P=0.03);预防组真菌定植11

  6. Laboratory culture of the freshwater benthic gastropod Bellamya aeruginosa (Reeve) and its utility as a test species for sediment toxicity.

    Science.gov (United States)

    Ma, Taowu; Gong, Shuangjiao; Zhou, Ke; Zhu, Cheng; Deng, Kaidong; Luo, Qinghua; Wang, Zijian

    2010-01-01

    This study aimed to develop original laboratory culture and sediment toxicity testing protocols for the freshwater gastropod Bellamya aeruginosa (Reeve), a new potential species for sediment toxicity testing. B. aeruginosa was successfully cultured with an effective culture system under proposed laboratory conditions. Optimal ad libitum feeding levels for larvae, juveniles, and adults were 2.0, 6.0, and 16.0 mg fish food/(snail x day), respectively. Mean survival rates of juveniles were higher than 90%. The snails could be sexed at 9 weeks of age, and their generation time is approximately 4 months. Reproduction continued all year around; the mean fecundity was 0.55 newborn/(female x day). The utility of this species for bioassays was evaluated in both 10-day and 28-day case studies with artificial sediments. The 10-day LC50 of Cu for larvae was 480 gg/g dry weight (dw), and the lowest observed effects concentration of Cu for survival and growth of larvae was 195 microg/g dw. Survival and growth are reliable indicators of acute toxicity. Larvae accumulated more Cu than adults. B. aeruginosa exhibited a higher sensitivity to Cu exposure than standard test species (Hyalella azteca and Chironomus tentans). The 28-day test of sediment toxicity with adults showed that fecundity was a robust endpoint indicator of reproductive toxicity, and the biochemical endpoints of superoxide dismutase, catalase, and glutathione could be used as sensitive biomarkers for Cu-induced oxidative damage. B. aeruginosa can be therefore recommended as a candidate for the standardization of the freshwater sediment toxicity test protocol.

  7. El amor no surge de los "ojos" sino de los "oídos": Asociaciones semánticas en lenguas yuto-aztecas (Love does not emerge from the "eyes" but from the "ears": Semantic associations in Uto-Aztecan languages

    Directory of Open Access Journals (Sweden)

    Lilián Guerrero

    2010-06-01

    Full Text Available Las asociaciones semánticas entre el vocabulario de partes del cuerpo y verbos de percepción física constituyen un patrón casi universal. Dentro del dominio de la percepción, se ha evidenciado la supremacía de los 'ojos' y la 'visión' como fuentes metafóricas no solo para otros verbos sensoriales ('ver' > 'oír', sino también de otros predicados cognitivos (Viberg, 1984; Sweetser, 1990. Los 'oídos' y la 'audición', en cambio, apenas se mencionan en estos patrones de cambio semántico (Evans y Wilkins, 2000. El presente estudio explora las extensiones semánticas de partes del cuerpo y modalidad sensorial en la familia yuto-azteca. Más que la visión, las lenguas yuto-aztecas prefieren la audición, seguida de otras sedes corporales como 'mente/corazón' y 'sangre', para desarrollar predicados de percepción física, intelectual y emocional. (The semantic associations between the lexicon of body parts and physical perception are almost universal. Within the domain of perception, it has been pointed out the supremacy of the 'eyes' and the 'visual' sense as metaphorical sources for other sensorial verbs ('see' > 'hear' as well as other cognitive domains (Viberg, 1984; Sweetser, 1990. In contrast, the 'ears' and the auditory modality are barely mentioned within these patterns of semantic changes (Evans and Wilkins, 2000. The present study explores the semantic extension of body parts and sensory verbs within the Yuto-Aztecan family. Rather than the vision, Yuto-Aztecan languages prefer the 'ears' and 'hearing', together to other vital body parts such as 'mind/heart' and 'blood', to develop physical, intellectual and emotional perception predicates.

  8. Aztecas Del Norte: The Chicanos of Aztlan.

    Science.gov (United States)

    Forbes, Jack D.

    The purpose of this book is to examine the Indian heritage of the Mexican Americans of the Southwest. It covers Mexican American history from the time of the Aztecs to the present. In the introduction, the Mexican approach to United States history is discussed. Topics covered are: the Tollecayotl and Mexicayotl heritage; the northward movement;…

  9. Aztecas Del Norte: The Chicanos of Aztlan.

    Science.gov (United States)

    Forbes, Jack D.

    The purpose of this book is to examine the Indian heritage of the Mexican Americans of the Southwest. It covers Mexican American history from the time of the Aztecs to the present. In the introduction, the Mexican approach to United States history is discussed. Topics covered are: the Tollecayotl and Mexicayotl heritage; the northward movement;…

  10. Romania in 10 days. Sensational stories – the profile of a TV channel

    Directory of Open Access Journals (Sweden)

    Nicoleta CORBU

    2008-01-01

    Full Text Available This article presents the profile of the most famous private TV channel in Romania, PROTV, in a comparative analysis with the public national television, TVR. The analysis (a corpus of 7 p.m. “PROTV News”, from 6 to 16 October 2007 will be focused on the sensational aspect of the news presented in the main News Bulletin, as preferred theme of the news presented on this private TV station, theme which defines in a way its profile, an obvious preference for the tabloidlike subjects, sensational ones, compared mainly with those of the public station which has a preference for news from political life. The comparative analysis concerns two main aspects, the theme of the news and their length, while the profile of the private station will be completed by a semantic analysis of the titles of the news, of the way of the presenters’ way of speaking etc. All these aspects will lead to general questions about the nature of information presented on the news nowadays, the way “reality” is constructed by the television etc.

  11. Behaviour of captive Ostrich chicks from 10 days to 5 months of age

    Directory of Open Access Journals (Sweden)

    Marina Freire Amado

    2011-07-01

    Full Text Available The behaviour of ostrich chicks bred in captivity was studied by using groups with 30 birds in five age groups: from 10 to 40 days of age; from 41 to 60 days of age; from 61 to 90 days of age; from 91 to 120 days of age and from 121 to 150 days of age. Six birds at each age were ringed around one of their feet and observed for four consecutive days for eight hours daily in three periods (in the morning, at noon and in the afternoon, following the "one-zero" method for sampling. The order for observation of behaviour of the six selected birds was performed randomly at every thirty minutes, totalling 16 periods or 80 minutes/bird/day. Fourteen types of behaviour were observed. There were differences among ages for behaviour like standing, walking, running, ingesting stones, ingesting feces, picking and attacking. Non-parametric-tests were used to analyse the behaviour according to age of the bird and to the periods of the day. There was a statistical difference between in the morning and at noon periods on behaviours standing, walking, eating ration and in litophagia, which were observed more frequently at the first hours of the day. When periods of the morning and afternoon were compared, the birds' age had a significant effect on behaviour sand bathing. When the periods noon/afternoon were compared, the behaviours which presented significant differences were walking, running, drinking water, eating ration, litophagia, coprophagia, dancing, sand bathing, whose occurrence was the highest during dusk. It was observed that the behaviour of young ostriches diverge according to the age and to day period.

  12. Swim Free. A 10 Day Program of Aquatic Exercises Adapted from Life in the Waterworld.

    Science.gov (United States)

    Eberhardt, Lorraine; Sanborn, Laura

    The completely waterproof book contains instructions for an alternative form of swimming exercises based on the movements of 19 water creatures. The exercises can be used by groups or individuals to enhance training programs, to serve as part of a structured synchronized swimming program, or to supplement recreational activities. The book provides…

  13. 76 FR 45645 - 10-Day Notice of Proposed Information Collection: Technology Security/Clearance Plans, Screening...

    Science.gov (United States)

    2011-07-29

    ...The Department of State has submitted the following information collection request to the Office of Management and Budget (OMB) for approval in accordance with the Paperwork Reduction Act of 1995. Title of Information Collection: Technology Security/ Clearance Plans, Screening Records, and Non-Disclosure Agreements Pursuant to 22 CFR 126.18. OMB Control Number: 1405-XXXX.......

  14. 77 FR 64759 - Rescission of 10-Day Agency Discretionary Period in Assigning Unsatisfactory Safety Ratings

    Science.gov (United States)

    2012-10-23

    ..., page 27, published July 21, 2012. Legal Basis for Rulemaking The legal basis for this final rule is... to an additional 60 days at the Agency's discretion. FMCSA has updated the terminology used for motor carriers transporting hazardous materials to be consistent with terminology used elsewhere in this part. If...

  15. Increases in Global and Domain Specific Self-Esteem Following a 10 Day Developmental Voyage

    Science.gov (United States)

    Grocott, Andrew C.; Hunter, John A.

    2009-01-01

    Although positive effects are often reported, research assessing the impact of Adventure Education and Outward Bound programmes on self-esteem is fraught with methodological weaknesses pertaining to an emphasis on scales assessing global self-esteem, a lack of follow-up measures to assess the potential long-term benefits of such programmes and…

  16. Boffins send 60 million MB around the world in 10 days

    CERN Multimedia

    Farrell, Nick

    2005-01-01

    In one of the world's biggest grid computing projects, UK boffins at Rutherford Appleton Laboratory (EAL) in Oxfordshire managed to transfer 60 million megabytes of data aroung the world in ten days (1/2 page)

  17. Evaluation of the Ration, Cold Weather during a 10-Day Cold Weather Field Training Exercise

    Science.gov (United States)

    1987-06-15

    Bars Oatmeals Strawberry Granola Bars Oatmeal Cookies Cookies, Choco Covered Kaielnut Crunch Blueberry Bars Chocolate Bars Cider Orange...Chicken a la King Oatmeal, Maple Granola Bare OatBcal Cookias Cookies, Choco Covered Raisinut Crunch Fig Bars Chocolate Bars Cider. Orange

  18. Ovarian Grafts 10 Days after Xenotransplantation: Folliculogenesis and Recovery of Viable Oocytes.

    Directory of Open Access Journals (Sweden)

    Paulo Henrique Almeida Campos-Junior

    Full Text Available Ovarian xenotransplantation is a promising alternative to preserve fertility of oncologic patients. However, several functional aspects of this procedure remained to be addressed. The aim of this study was evaluate the feasibility of xenotransplantation as a strategy to maintain bovine ovarian grafts and produce oocytes. Adult ovarian cortical pieces were xenotransplanted to the dorsal subcutaneous of female NOD-SCID mice (n = 62. Grafts were recovered ten days after xenotransplantation. Host and graft weights; folliculogenesis progression; blood perfusion, relative gene expression and number of macrophage and neutrophil of xenografts; in vitro developmental competence of graft-derived oocytes were evaluated. Folliculogenesis was supported in the grafts, as indicated by the presence of primordial, primary, secondary, antral, and atretic follicles. The xenografts showed a greater volumetric density of atretic follicles and higher hyperemia and number of host-derived macrophage and neutrophil (P<0.05, when compared to non-grafted fragments. There was a higher blood perfusion under the back skin in the transplantation sites of host animals than in control and non-grafted (P<0.01. BAX and PRDX1 genes were up-regulated, while BCL2, FSHR, IGF1R and IGF2R were down-regulated, when compared to the control (P<0.01. Twenty seven oocytes were successfully harvested from grafts, and some of these oocytes were able to give rise to blastocysts after in vitro fertilization. However, cleavage and blastocyst rates of xenograft derived oocytes were lower than in control (P<0.01. Despite showing some functional modifications, the ovarian xenografts were able to support folliculogenesis and produce functional oocytes.

  19. Fungal propagules and DNA in feces of two detritus-feeding amphipods.

    Science.gov (United States)

    Sridhar, Kandikere Ramaiah; Beaton, Margaret; Bärlocher, Felix

    2011-01-01

    Aquatic shredders (leaf-eating invertebrates) preferentially ingest and digest leaves colonized by aquatic hyphomycetes (fungi). This activity destroys leaf-associated fungal biomass and detritial resources in streams. Fungal counter-adaptations may include the ability to survive passage through the invertebrate's digestive tract. When fecal pellets of Gammarus tigrinus and Hyalella azteca were incubated with sterile leaves, spores of nine (G. tigrinus) and seven (H. azteca) aquatic hyphomycete species were subsequently released from the leaves, indicating the presence of viable fungal structures in the feces. Extraction, amplification, and sequencing of DNA from feces revealed numerous fungal phylotypes, two of which could be assigned unequivocally to an aquatic hyphomycete. The estimated contributions of major fungal groups varied depending on whether 18S or ITS sequences were amplified and cloned. We conclude that a variable proportion of fungal DNA in the feces of detritivores may originate from aquatic hyphomycetes. Amplified DNA may be associated with metabolically active, dormant, or dead fungal cells.

  20. Chronic effects of CuO Nanoparticles on Lymnaea stagnalis

    DEFF Research Database (Denmark)

    Falk, Nina; Zwicky, Julie; Rewentlow, Julie

    Due to their small size and high surface-to-volume ratio, the properties and reactivity of NPs are different from those of their bulk forms. However, these properties might cause different behaviour and effects in the environment and investigations of possible nano specific effects are thus highl...... relevant. Investigation of the long-term effects of CuO NPs on growth, mortality and precopulation of Hyalella azteca compared to CuCl2 and to further examine possible delayed effects and ability to recover from Cu exposure....

  1. Biological hazard evaluation of a pharmaceutical effluent before and after a photo-Fenton treatment.

    Science.gov (United States)

    Novoa-Luna, Karen Adriana; Mendoza-Zepeda, Arisbeht; Natividad, Reyna; Romero, Rubi; Galar-Martínez, Marcela; Gómez-Oliván, Leobardo Manuel

    2016-11-01

    The aim of this study was to evaluate the biological hazard of a pharmaceutical effluent before and after treatment. For the former, the determined 96h-LC50 value was 1.2%. The photo-Fenton treatment catalyzed with an iron-pillared clay reduced this parameter by 341.7%. Statistically significant increases with respect to the control group (Pheterogeneous photo-Fenton process decreases the presence of PCT, oxidative stress, genotoxic damage and LC50 in Hyalella azteca. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Amphipod densities and indices of wetland quality across the upper-Midwest, USA

    Science.gov (United States)

    Anteau, M.J.; Afton, A.D.

    2008-01-01

    Nutritional, behavioral, and diet data for lesser scaup (Aythya affinis [Eyton, 1838]) indicates that there has been a decrease in amphipod (Gammarus lacustris [G. O. Sars, 1863] and Hyalella azteca [Saussure, 1858]) density and wetland quality throughout the upper-Midwest, USA. Accordingly, we estimated densities of Gammarus and Hyalella in six eco-physiographic regions of Iowa, Minnesota, and North Dakota; 356 randomly selected semipermanent and permanent wetlands were sampled during springs 2004 and 2005. We also examined indices of wetland quality (e.g., turbidity, fish communities, aquatic vegetation) among regions in a random subset of these wetlands (n = 267). Gammarus and Hyalella were present in 19% and 54% of wetlands sampled, respectively. Gammarus and Hyalella densities in North Dakota were higher than those in Iowa and Minnesota. Although historical data are limited, our regional mean (1 to 12 m-3) amphipod densities (Gammarus + Hyalella) were markedly lower than any of the historical density estimates. Fish, important predators of amphipods, occurred in 31%-45% of wetlands in North Dakota, 84% of wetlands in the Red River Valley, and 74%-84% of wetlands in Iowa and Minnesota. Turbidity in wetlands of Minnesota Morainal (4.0 NTU geometric mean) and Red River Valley (6.1 NTU) regions appeared low relative to that of the rest of the upper-Midwest (13.2-17.5 NTU). We conclude that observed estimates of amphipods, fish, and turbidity are consistent with low wetland quality, which has resulted in lower food availability for various wildlife species, especially lesser scaup, which use these wetlands in the upper-Midwest. ?? 2008, The Society of Wetland Scientists.

  3. Thallium contamination of water in Canada

    Energy Technology Data Exchange (ETDEWEB)

    Cheam, V. [National Water Research Institute Branch, Burlington, ON (Canada). Aquatic Ecosystems Protection Research Branch

    2001-07-01

    A highly sensitive instrument, a Laser-Excited Atomic Fluorescence Spectrometer, has been developed to study thallium contamination in some important Canadian ecosystems from the Arctic (containing very low thallium concentration) to coal-related industries across Canada and even to the study of thallium toxicity in an invertebrate, Hyalella azteca. Overall, the data indicate that the coal power plants and mines contain higher thallium concentrations than the other ecosystems studied, and the eastern region has the highest Tl concentrations compared to other regions. The range of thallium concentration in ng/L for the Arctic snow and ice was between not detected and 8.4, for the Great Lakes waters 0.9 to 48, for pore waters 0.1 to 213, for western coal power plants and mines 0.1 to 1326, for central coal power plants 1.2 to 175, for eastern coal power plants and mines 0.2 to 23605, and for miscellaneous sites across Canada not detected to 4390 ng/L. Some of these high concentrations and those high ones reported in industrial wastewaters exceeded the chronic toxicity endpoints for Hyalella azteca mortality, growth and reproduction, and thus can cause serious distress to the environment. All data were integrated into a map of thallium distribution, the first one in Canada. Natural background level of thallium for the Arctic was estimated to be 0.02 to 0.03 pg/g.

  4. Una principessa azteca: Tecuichpotzin Ichcaxochitzin – Isabel de Moctezuma

    Directory of Open Access Journals (Sweden)

    Rosa Maria Grillo

    2016-12-01

    Full Text Available In the framework of the ‘gender studies’ dedicated to forgotten women in history, a prominent place is occupied by Tecuichpotzin Ichcaxochitzin (“Cotton flower, the revered daughter of the lord”   daughter of Moctezuma II, was probably born at the end of the first decade of the sixteenth century. Baptized as Isabel de Moctezuma, she lived a life straddling two worlds and two eras: daughter and wife of kings, repudiated by Cortés, she is sometimes described as the anti Malinche, loyal to her people but perfectly integrated in the colonial system. This paper will compare different sources – historical chronicles of that time and subsequent periods, historical fiction   in order to provide a credible profile and to correctly interpret such contradictory comments and opinions.

  5. El Calendario Azteca - para Colorear. (The Aztec Calendar - for Coloring.)

    Science.gov (United States)

    1977

    The Aztec calendar had a different god representing each month of the year. This color-by-number book illustrates each god and gives its name and the month it represents in Spanish. Each part of the god is numbered from 1 to 20 with a color corresponding to each number. (NQ)

  6. El Calendario Azteca - para Colorear. (The Aztec Calendar - for Coloring.)

    Science.gov (United States)

    1977

    The Aztec calendar had a different god representing each month of the year. This color-by-number book illustrates each god and gives its name and the month it represents in Spanish. Each part of the god is numbered from 1 to 20 with a color corresponding to each number. (NQ)

  7. Pulmonary lesions and clinical disease response to Mannheimia haemolytica challenge 10 days following administration of tildipirosin or tulathromycin.

    Science.gov (United States)

    Amrine, D E; White, B J; Larson, R L; Mosier, D A

    2014-01-01

    This clinical trial evaluated the impact of metaphylactic antimicrobial administration 10 d before experimental inoculation with Mannheimia haemolytica (MH) to mitigate pulmonary lesions. Thirty-three crossbreed heifers were procured as a single group and were randomly allocated to 1 of 3 blocks and to treatment, tildipirosin (ZUP; 4 mg/kg) or tulathromycin (DRX; 2.5 mg/kg) or saline (SAL; 1 mL/45.5 kg), within block on arrival at Kansas State University. All trial procedures were staggered by 7-d intervals for each block, resulting in all animals within a block receiving treatment, challenge, and necropsy on the same dates. Heifers within each block received an endoscopic MH challenge 10 d following treatment administration (d 0) and were housed in individual indoor stalls for 3 d postchallenge. Clinical illness scores (CIS), respiration quality scores, appetite scores, and injection site reactions were recorded on all animals from d 0 through d 13. Rectal temperatures were measured once daily on all animals from d 8 through d 13. Heifers were necropsied, and lung lesions were evaluated on d 13. Lung lesion data were evaluated using nonparametric methods (Kruskall-Wallis), and standard least squares models were used to evaluate the remaining variables. The pulmonary lesion scores (percentage of affected lung) ranged from 3.3% to 39.8% for all heifers with 92% (11/12) of ZUP-treated heifers having <10% lesions. Tildipirosin-treated heifers had lower (P < 0.05) lung lesion scores when compared with DRX- and SAL-treated heifers. Lung weight expressed as a percentage of BW was lower (P < 0.05) in ZUP heifers compared to DRX- and SAL-treated heifers. The probability of receiving abnormal CIS, appetite scores, and respiratory scores was lower (P < 0.05) in ZUP-treated heifers compared to DRX- and SAL-treated animals. This study showed that heifers treated with tildipirosin 10 d before MH challenge have less pulmonary damage and fewer clinical signs of illness compared to heifers treated with DRX or SAL.

  8. Needle in a haystack-parathyroid gland in a 10-day old infant: a case report and literature review.

    Science.gov (United States)

    Ismail, Adel; Abbas, Tariq O; Al-Khalaf, Fawziya

    2011-01-01

    Neonatal severe primary hyperparathyroidism (NSPHT) is a rare autosomal recessive disorder of calcium homeostasis. It presents shortly after birth and is characterized by striking hyperparathyroidism, marked hypercalcemia, and hyperparathyroid bone disease. It is caused by mutations of the calcium-sensing receptor (CASR), the ionized calcium sensor for the parathyroid cells, the parafollicular thyroid C cells, and the kidney epithelium, as well as cells in bone and intestine. Without early intervention, which frequently requires surgical removal of the hyperplastic parathyroids, the patients often succumb to complications of hypercalcemia and respiratory failure. Finding the parathyroid gland in small neonates is not an easy task. Here we report on a patient with neonatal hyperparathyroidism who was treated by total parathyroidectomy and discuss the various ways of helping to find the parathyroid glands during surgery at this young age.

  9. Endothelial function after 10 days of bed rest in individuals at risk for type 2 diabetes and cardiovascular disease

    DEFF Research Database (Denmark)

    Sonne, Mette Paulii; Højbjerre, Lise; Alibegovic, Amra C;

    2011-01-01

    Aims: Physical inactivity is considered to be deleterious to vascular health, and in particular first degree relatives to patients with type 2 diabetes (FDR) and persons born with low birth weight (LBW) who may later in life develop cardiovascular disease. A period of imposed physical inactivity...... rest impaired insulin-mediated vasodilatation in CON and LBW and increased endothelial activation markers in FDR and LBW but not in CON. Vasodilator responses were very low in FDR even prior to, and did not decrease further, during bed rest. Conclusion: Physical inactivity does not impair endothelial...

  10. A 10-day heatwave at flowering superimposed on climate change conditions strongly affects production of 22 barley accessions

    DEFF Research Database (Denmark)

    Ingvordsen, Cathrine Heinz; Lyngkjær, Michael F.; Peltonen-Sainio, Pirjo

    Extreme climate events are projected to be among the future most challenging constraints to plant development. Heatwaves as well as floods and droughts cause acute changes in the growth environment determining our primary production (Collins et al., 2013). Europe experienced extreme heatwaves...... and incorporate them in breeding programs....

  11. CoRoT-22 b: a validated 4.9 RE exoplanet in 10-day orbit

    CERN Document Server

    Moutou, C; Diaz, R F; Alonso, R; Deleuil, M; Guenther, E; Pasternacki, T; Aigrain, S; Baglin, A; Barge, P; Bonomo, A; Borde, P; Bouchy, F; Cabrera, J; Carpano, S; Cochran, W; Csizmadia, Sz; Deeg, H; Dvorak, R; Endl, M; Erikson, A; Ferraz-Mello, S; Gandolfi, D; Guillot, T; Artzes, A; Hebrard, G; Lovis, C; Lammer, H; McQueen, P; Mazeh, T; Ofir, A; Ollivier, M; Paetzold, M; Rauer, H; Rouan, D; Santerne, A; Schneider, J; Tingley, B; Wuchterl, G

    2014-01-01

    The CoRoT satellite has provided high-precision photometric light curves for more than 163,000 stars and found several hundreds of transiting systems compatible with a planetary scenario. If ground-based velocimetric observations are the best way to identify the actual planets among many possible configurations of eclipsing binary systems, recent transit surveys have shown that it is not always within reach of the radial-velocity detection limits. In this paper, we present a transiting exoplanet candidate discovered by CoRoT whose nature cannot be established from ground-based observations, and where extensive analyses are used to validate the planet scenario. They are based on observing constraints from radial-velocity spectroscopy, adaptive optics imaging and the CoRoT transit shape, as well as from priors on stellar populations, planet and multiple stellar systems frequency. We use the fully Bayesian approach developed in the PASTIS analysis software, and conclude that the planet scenario is at least 1400 ...

  12. Speciation and bioavailability of zinc in amended sediments

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Aaron G.B.; Scheckel, Kirk G.; McDermott, Gregory; Gratson, David; Neptune, Dean; Ryan, James A.

    2011-12-09

    The speciation and bioavailability of zinc (Zn) in smelter-contaminated sediments were investigated as a function of phosphate (apatite) and organic amendment loading rate. Zinc species identified in preamendment sediment were zinc hydroxide-like phases, sphalerite, and zinc sorbed to an iron oxide via X-ray adsorption near edge structure (XANES) spectroscopy. Four months after adding the amendments to the contaminated sediment, hopeite, a Zn phosphate mineral, was identified indicating phosphate was binding and sequestering available Zn and Zn pore water concentrations were decreased at levels of 90% or more. Laboratory experiments indicate organic amendments exhibit a limited effect and may hinder sequestration of pore water Zn when mixed with apatite. The acute toxicity of the sediment Zn was evaluated with Hyalella azteca, and bioaccumulation of Zn with Lumbriculus variegates. The survivability of H. azteca increased as a function of phosphate (apatite) loading rate. In contaminated sediment without apatite, no specimens of H. azteca survived. The bioaccumulation of Zn in L. variegates also followed a trend of decreased bioaccumulation with increased phosphate loading in the contaminated sediment. The research supports an association between Zn speciation and bioavailability.

  13. Trait-based modelling of bioaccumulation by freshwater benthic invertebrates.

    Science.gov (United States)

    Sidney, Livia Alvarenga; Diepens, Noël J; Guo, Xiaoying; Koelmans, Albert A

    2016-07-01

    Understanding the role of species traits in chemical exposure is crucial for bioaccumulation and toxicity assessment of chemicals. We measured and modelled bioaccumulation of polychlorinated biphenyls (PCBs) in Chironomus riparius, Hyalella azteca, Lumbriculus variegatus and Sphaerium corneum. We used a battery test procedure with multiple enclosures in one aquarium, which maximized uniformity of exposure for the different species, such that the remaining variability was due mostly to species traits. The relative importance of uptake from either pore water or sediment ingestion was manipulated by using 28 d aged standard OECD sediment with low (1%) and medium (5%) OM content and 13 months aged sediment with medium OM (5%) content. Survival was ≥76% and wet weight increased for all species. Reproduction of H. azteca and weight gain of H. azteca and S. corneum were significantly higher in the medium OM aged sediments than in other sediments, perhaps due to a more developed microbial community (i.e., increase in food resources). Biota-sediment accumulation factors (BSAF) ranged from 3 to 114, depending on species and PCB congener, with C. riparius (3-10)bioaccumulation model with species-specific bioaccumulation parameters fitted well to the experimental data and showed that bioaccumulation parameters were depended on species traits. Enclosure-based battery tests and mechanistic BSAF models are expected to improve the quality of the exposure assessment in whole sediment toxicity tests.

  14. Mercury-contaminated sediments affect amphipod feeding.

    Science.gov (United States)

    Bundschuh, Mirco; Zubrod, Jochen P; Seitz, Frank; Newman, Michael C; Schulz, Ralf

    2011-04-01

    A 125-mile reach of the South River, Virginia, was contaminated with mercury during the first half of the 20th century. As increased concentrations of mercury have persisted, researchers have carefully studied its distribution in the river biota and estimated associated risks. The present study evaluated the influence of mercury on feeding rate and uptake by the amphipod Hyalella azteca. The test organisms were exposed for 7 days with leaf discs to reference and contaminated field sediment during the preliminary experiment and additionally to Sedimite (a commercial mercury-sequestering agent) amended sediments during the final experiment. The preliminary experiment demonstrated a decreased feeding rate (approximately 35%) of H. azteca in sediment from a contaminated site relative to sediment from a reference site. The test design of the final experiment took advantage of the knowledge gained in the preliminary experiment by increasing the number of replicates, which decreased the type II error rate. First, the results of the final experiment confirmed the results of the preliminary experiment by again demonstrating differences in the feeding rate of approximately 35% between reference and contaminated sediment. Second, the results indicated a lower feeding rate in reference sediment in the presence of Sedimite. Third, an opposite tendency, although not significant, was apparent for Sedimite-amended contaminated sediment. Thus, Sedimite appears to decrease sediment quality, whereas this conclusion is based on the feeding rate of H. azteca. However, Sedimite and its value as a mercury-sequestering agent requires further evaluation.

  15. Evaluation of the effect of water type on the toxicity of nitrate to aquatic organisms.

    Science.gov (United States)

    Baker, Josh A; Gilron, Guy; Chalmers, Ben A; Elphick, James R

    2017-02-01

    A suite of acute and chronic toxicity tests were conducted to evaluate the sensitivity of freshwater organisms to nitrate (as sodium nitrate). Acute exposures with rainbow trout (Onchorhynchus mykiss) and amphipods (Hyalella azteca), as well as chronic exposures with H. azteca (14-d survival and growth), midges (Chironomus dilutus; 10-d survival and growth), daphnids (Ceriodaphnia dubia; 7-d survival and reproduction), and fathead minnows (Pimephales promelas; 7-d survival and growth) were used to determine sublethal and lethal effect concentrations. Modification of nitrate toxicity was investigated across a range of ionic strengths, created through the use of very soft water, and standard preparations of synthetic soft, moderately-hard and hard dilution waters. The most sensitive species tested were C. dubia and H. azteca, in soft water, with reproduction and growth IC25 values of 13.8 and 12.2 mg/L NO3-N, respectively. All of the organisms exposed to nitrate demonstrated significantly reduced effects with increasing ionic strength associated with changes in water type. Possible mechanisms responsible for the modifying effect of increasing major ion concentrations on nitrate toxicity are discussed.

  16. Proteomics in aquatic amphipods: can it be used to determine mechanisms of toxicity and interspecies responses after exposure to atrazine?

    Science.gov (United States)

    Ralston-Hooper, Kimberly J; Sanchez, Brian C; Adamec, Jiri; Sepúlveda, María S

    2011-05-01

    Proteomics has gained popularity in the field of ecotoxicology as a holistic tool for unraveling novel mechanisms of toxicity and elucidating subtle effects of contaminant exposure. The holoarctic amphipod Diporeia spp. is declining at precipitous rates in the Great Lakes, and we are evaluating the use of the well-studied amphipod model Hyalella azteca as a surrogate for Diporeia spp. This article presents proteomics data from both amphipod species exposed to atrazine (ATZ) and one of its metabolites, desethylatrazine (DEA; 3 and 30 µg/L for 21 and 42 d). We used a proteomics approach to determine whether these two species of amphipods responded similarly to the same chemicals and to understand better the mechanisms of toxicity of ATZ and DEA in aquatic invertebrates. We observed disruption in energy production and mitochondrial function as well as hormesis in exposed organisms. In addition, we identified a two proteins (GAPDH and HSP 90 kDa) that have been linked to hormonal disruptions, suggesting potential endocrine disruption. Finally, we found that H. azteca and Diporeia spp. responded with similar proteomic profiles after ATZ and DEA exposure, suggesting that H. azteca may be used as a surrogate model organism for Diporeia spp.

  17. Subcatchment deltas and upland features influence multiscale aquatic ecosystem recovery in damaged landscapes.

    Science.gov (United States)

    Kielstra, Brian W; Arnott, Shelley E; Gunn, John M

    2017-08-07

    Assessing biological recovery in damaged aquatic environments requires the consideration of multiple spatial and temporal scales. Past research has focused on assessing lake recovery from atmospheric or catchment disturbance at regional or catchment levels. Studies have also rarely considered the influences of adjacent terrestrial characteristics on within-lake habitats, such as subcatchment delta confluences. We used Hyalella azteca, a ubiquitous freshwater amphipod, as a sensitive indicator to assess the importance of local subcatchment scale factors in the context of multiscale lake recovery within the metal mining region of Sudbury, Canada following a period of major reductions in atmospheric pollution. At the regional scale, data from repeated surveys of 40 lakes showed higher probabilities of H. azteca occurrence with higher lake water conductivity, alkalinity, and pH and lower metal concentrations. The importance of metals decreased through time and the importance of higher conductivity, alkalinity, and pH increased. At the subcatchment scale, a subset of six lakes sampled across a colonization gradient revealed higher H. azteca abundances at subcatchment delta sites than non-delta sites in early colonization stages, and that abundance at delta sites was correlated with both within-lake habitat and terrestrial subcatchment characteristics. For example, wetland cover reduced the strength of positive associations between H. azteca abundance and macrophyte density. A single lake from this subset also revealed higher abundances at delta sites associated with higher concentrations of terrestrial organic matter and larger subcatchments. Our results demonstrate that factors affecting recovery can change with the scale of study, and that managing terrestrial-aquatic linkages is important for facilitating recovery processes within damaged lake ecosystems. © 2017 by the Ecological Society of America.

  18. Phototoxicity of TiO{sub 2} nanoparticles to a freshwater benthic amphipod: Are benthic systems at risk?

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shibin, E-mail: li.shibin@epa.gov [U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Duluth, MN (United States); Wallis, Lindsay K.; Ma, Hongbo [U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Duluth, MN (United States); Diamond, Stephen A. [Nanosafe Inc., Blacksburg, VA (United States)

    2014-01-01

    This study investigated phototoxicity of TiO{sub 2} nanoparticles (nano-TiO{sub 2}) to a freshwater benthic amphipod (Hyalella azteca) using 48-h and 96-h bioassays. Thorough monitoring of particle interactions with exposure media (Lake Superior water, LSW) and the surface of organisms was performed using dynamic light scattering, UV/Vis spectroscopy, and Scanning Electron Microscopy. Large agglomeration and sedimentation (> 77%) in LSW was observed after 0.5 h. A simulated solar radiation (SSR)-favored surface attachment of nanoparticles was observed, indicating enhanced phototoxicity with the increased attachment. A 96-h median lethal concentration (LC50) of 29.9 mg/L in H. azteca was calculated, with a daily 4-h UV exposure of 2.2 W/m{sup 2}. Phototoxicity of nano-TiO{sub 2} under SSR had a 21-fold increase as compared to that under ambient laboratory light. This phototoxicity was also dependent on UV dose, with calculated LC50s around 22.9 (95% CI, 20.5–23.3) Wh/m{sup 2} when exposed to 20 mg/L nano-TiO{sub 2}. Also, H. azteca exhibited negative phototaxis in the presence of shelters, indicating that other factors might play a role in environmental systems. Finally, the environmental implications of nano-TiO{sub 2} to benthic organisms were illustrated, emphasizing the importance of various environmental factors in the ultimate phototoxicity. This increased phototoxicity and its complex interactions with various environmental factors suggest further investigations are needed for future risk assessment of photoactive nanomaterials to benthic organisms. - Graphical abstract: Display Omitted - Highlights: •Large aggregation of TiO{sub 2} nanoparticles in Lake Superior water was observed. •Phototoxicity was dependent on the dose of both solar radiation and nanoparticle. •A solar radiation favored surface attachment of nanoparticles was observed. •Hyalella azteca exhibited negative phototaxis in the presence of shelters. •Factors influencing

  19. Invasive alien species water hyacinth Eichhornia crassipes as abode for macroinvertebrates in hypertrophic Ramsar Site, Lake Xochimilco, Mexico.

    Science.gov (United States)

    Rocha-Ramirez, A; Robles-Valderrama, E; Ramirez-Flores, E

    2014-11-01

    This paper presents information on the density, diversity and functional feeding groups of macroinvertebrate assemblages associated with water hyacinth in Antiguo Canal Cuemanco, part of Lake Xochimilco in Mexico City. Rare (low frequency and density) and dominant (high frequency and density) taxa prevailed in the assemblages, with the most predominant being Hyalella azteca, Chironomus plumosus and Ischnura denticollis. Nonmetric Multidimensional Scaling confirmed two climatic seasons: warm-rainy and cold-dry; the former with the highest diversity and density of taxa. Canonical Correspondence Analysis showed that conductivity, nitrates and turbidity explained the density variations of taxa. Antiguo Canal Cuemanco waters are spatially homogeneous with the characteristics of hypertrophic shallow lakes, inhabited by scrapers and gathering-collectors. The species found were tolerant to organic pollution.

  20. Contaminants, water quality, and wildlife mortality on oil production sites in western South Dakota. Interim report

    Energy Technology Data Exchange (ETDEWEB)

    Henry, C.J.; Ruelle, R.

    1993-04-01

    The objectives of the study were to evaluate oil pits and other hazards at oil production sites to (1) document the magnitude of wildlife mortality due to exposure to oil and other chemicals, (2) determine the physical and toxic effects of oil pit contents on wildlife, and (3) identify methods to prevent sublethal and lethal impacts to wildlife. Pits at oil production sites in Fall River and Harding Counties of western South Dakota were surveyed for wildlife carcasses by searching the shorelines and raking underwater around the pit edges in April, July, and October 1992. In July, composite water and sediment samples were collected from 26 pits, and analyzed for oil and grease. Bioassays were conducted with two life stages of Hyalella azteca and Daphnia magna to determine pit water toxicity. Seed germination tests were conducted using radish seeds exposed to pit water. Oil and poor water quality appeared to be the primary causes of pit liquid toxicity.

  1. Improving sediment-quality guidelines for nickel: development and application of predictive bioavailability models to assess chronic toxicity of nickel in freshwater sediments

    Science.gov (United States)

    Vangheluwe, Marnix L. U.; Verdonck, Frederik A. M.; Besser, John M.; Brumbaugh, William G.; Ingersoll, Christopher G.; Schlekat, Christan E.; Rogevich Garman, Emily

    2013-01-01

    Within the framework of European Union chemical legislations an extensive data set on the chronic toxicity of sediment nickel has been generated. In the initial phase of testing, tests were conducted with 8 taxa of benthic invertebrates in 2 nickel-spiked sediments, including 1 reasonable worst-case sediment with low concentrations of acid-volatile sulfide (AVS) and total organic carbon. The following species were tested: amphipods (Hyalella azteca, Gammarus pseudolimnaeus), mayflies (Hexagenia sp.), oligochaetes (Tubifex tubifex, Lumbriculus variegatus), mussels (Lampsilis siliquoidea), and midges (Chironomus dilutus, Chironomus riparius). In the second phase, tests were conducted with the most sensitive species in 6 additional spiked sediments, thus generating chronic toxicity data for a total of 8 nickel-spiked sediments. A species sensitivity distribution was elaborated based on 10% effective concentrations yielding a threshold value of 94 mg Ni/kg dry weight under reasonable worst-case conditions. Data from all sediments were used to model predictive bioavailability relationships between chronic toxicity thresholds (20% effective concentrations) and AVS and Fe, and these models were used to derive site-specific sediment-quality criteria. Normalization of toxicity values reduced the intersediment variability in toxicity values significantly for the amphipod species Hyalella azteca and G. pseudolimnaeus, but these relationships were less clearly defined for the mayfly Hexagenia sp. Application of the models to prevailing local conditions resulted in threshold values ranging from 126 mg to 281 mg Ni/kg dry weight, based on the AVS model, and 143 mg to 265 mg Ni/kg dry weight, based on the Fe model

  2. Identifying cause in sediment assessments : bioavailability and the sediment quality triad

    Energy Technology Data Exchange (ETDEWEB)

    Borgmann, U.; Norwood, W.P.; Reynoldson, T.B.; Rosa, F. [Environment Canada, Burlington, ON (Canada). National Water Research Inst.

    2001-05-01

    A study was conducted to examine the biological impacts of metals in sediments found in the Sudbury area lakes. This study included the analysis of the standard Sediment Quality Triad components from a 1996 study. Metal bioavailability or bioaccumulation in Hyalella azteca was also measured under laboratory conditions with fresh sediments collected in 1998 to determine the adequacy of the Sediment Quality Triad. The objective of the study was to determine first of all if contaminants are getting into the system, and if so, whether they are bioavailable. The second objective was to see if there is a measurable response and to determine what is causing the response. The application of the Sediment Quality Triad approach to non-pH-stressed area lakes showed increased levels of cadmium, cobalt, copper and nickel, with decreased amounts of benthic invertebrates and significant sediment toxicity to amphipods and mayflies. The cause of sediment toxicity was determined by comparing metal bioaccumulation with critical body concentrations previously shown to cause toxicity. Nickel was the only metal that was clearly identified as contributing to toxicity in chronic tests with Hyalella exposed to Sudbury area sediments. 31 refs., 3 tabs., 6 figs.

  3. Preliminary assessment of metal toxicity in the middle Tisza river (Hungary) flood plain

    Energy Technology Data Exchange (ETDEWEB)

    Black, M.C.; Williams, P.L. [Dept. of Environmental Health Science, Univ. of Georgia, Athens, GA (United States)

    2001-07-01

    Cyanide and heavy metals were accidentally released from a mine waste lagoon in Romania into tributaries ultimately draining into the Tisza River. Within two months of the cyanide accident two subsequent heavy metal waste spills further contaminated the Tisza River, followed by severe spring flooding, which potentially spread the contamination to soils adjacent to the river. Flood plain soils and shoreline sediments were sampled from two locations on the middle Tisza River and a reference site to conduct a preliminary assessment of metal content and toxicity. Ten-day sediment toxicity tests were conducted with the amphipod, Hyalella azteca and 24 h soil toxicity tests were conducted with the nematode (Caenorhabditis elegans). High concentrations of cadmium, copper, zinc, lead and arsenic were detected in soil and sediment samples. However, no mortality was observed in Hyalella exposed to Tisza River sediments and only up to 27% mortality of C. elegans was observed in flood plain soils. Low mortalities are attributed to reduced metal bioavailability caused by high soil cation exchange capacities and possible interactions with sediment organic matter or sulfides. Future studies should focus on factors that alter metal bioavailability and their relationship to potential toxicity of organisms exposed to Tisza River sediments and flood plain soils. (orig.)

  4. Methylmercury bioaccumulation in stream food webs declines with increasing primary production

    Science.gov (United States)

    Walters, David; D.F. Raikow,; C.R. Hammerschmidt,; M.G. Mehling,; A. Kovach,; J.T. Oris,

    2015-01-01

    Opposing hypotheses posit that increasing primary productivity should result in either greater or lesser contaminant accumulation in stream food webs. We conducted an experiment to evaluate primary productivity effects on MeHg accumulation in stream consumers. We varied light for 16 artificial streams creating a productivity gradient (oxygen production =0.048–0.71 mg O2 L–1 d–1) among streams. Two-level food webs were established consisting of phytoplankton/filter feeding clam, periphyton/grazing snail, and leaves/shredding amphipod (Hyalella azteca). Phytoplankton and periphyton biomass, along with MeHg removal from the water column, increased significantly with productivity, but MeHg concentrations in these primary producers declined. Methylmercury concentrations in clams and snails also declined with productivity, and consumer concentrations were strongly correlated with MeHg concentrations in primary producers. Heterotroph biomass on leaves, MeHg in leaves, and MeHg in Hyalella were unrelated to stream productivity. Our results support the hypothesis that contaminant bioaccumulation declines with stream primary production via the mechanism of bloom dilution (MeHg burden per cell decreases in algal blooms), extending patterns of contaminant accumulation documented in lakes to lotic systems.

  5. Lead Speciation and Bioavailability in Apatite-Amended Sediments

    Directory of Open Access Journals (Sweden)

    Kirk G. Scheckel

    2011-01-01

    Full Text Available The in situ sequestration of lead (Pb in sediment with a phosphate amendment was investigated by Pb speciation and bioavailability. Sediment Pb in preamendment samples was identified as galena (PbS with trace amounts of absorbed Pb. Sediment exposed to atmospheric conditions underwent conversion to hydrocerussite and anglesite. Sediments mixed with apatite exhibited limited conversion to pyromorphite, the hypothesized end product. Conversion of PbS to pyromorphite is inhibited under reducing conditions, and pyromorphite formation appears limited to reaction with pore water Pb and PbS oxidation products. Porewater Pb values were decreased by 94% or more when sediment was amended with apatite. The acute toxicity of the sediment Pb was evaluated with Hyalella azteca and bioaccumulation of Pb with Lumbriculus variegatus. The growth of H. azteca may be mildly inhibited in contaminated sediment, with apatite-amended sediments exhibiting on average a higher growth weight by approximately 20%. The bioaccumulation of Pb in L. variegatus tissue decreased with increased phosphate loading in contaminated sediment. The study indicates limited effectiveness of apatite in sequestering Pb if present as PbS under reducing conditions, but sequestration of porewater Pb and stabilization of near-surface sediment may be a feasible and alternative approach to decreasing potential toxicity of Pb.

  6. Identifying primary stressors impacting macroinvertebrates in the Salinas River (California, USA): Relative effects of pesticides and suspended particles

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, B.S. [Department of Environmental Toxicology, University of California, Davis, CA 95616 (United States)]. E-mail: anderson@ucdavis.edu; Phillips, B.M. [Department of Environmental Toxicology, University of California, Davis, CA 95616 (United States); Hunt, J.W. [Department of Environmental Toxicology, University of California, Davis, CA 95616 (United States); Connor, V. [Division of Water Quality, State Water Resources Control Board, 1001 I. Street, Sacramento, CA 95814 (United States); Richard, N. [Division of Water Quality, State Water Resources Control Board, 1001 I. Street, Sacramento, CA 95814 (United States); Tjeerdema, R.S. [Department of Environmental Toxicology, University of California, Davis, CA 95616 (United States)

    2006-06-15

    Laboratory dose-response experiments with organophosphate and pyrethroid pesticides, and dose-response experiments with increasing particle loads were used to determine which of these stressors were likely responsible for the toxicity and macroinvertebrate impacts previously observed in the Salinas River. Experiments were conducted with the amphipod Hyalella azteca, the baetid mayfly Procloeon sp., and the midge Chironomus dilutus (Shobanov, formerly Chironomus tentans). The results indicate the primary stressor impacting H. azteca was pesticides, including chlorpyrifos and permethrin. The mayfly Procloeon sp. was sensitive to chlorpyrifos and permethrin within the range of concentrations of these pesticides measured in the river. Chironomus dilutus were sensitive to chlorpyrifos within the ranges of concentrations measured in the river. None of the species tested were affected by turbidity as high as 1000 NTUs. The current study shows that pesticides are more important acute stressors of macroinvertebrates than suspended sediments in the Salinas River. - Pesticides are the primary stressor impacting macroinvertebrates in sections of the lower Salinas River.

  7. Occurrence and potential toxicity of pyrethroids and other insecticides in bed sediments of urban streams in central Texas

    Energy Technology Data Exchange (ETDEWEB)

    Hintzen, Emily P. [Department of Environmental Studies, Baylor University, Waco, TX 76798 (United States); Lydy, Michael J. [Fisheries and Illinois Aquaculture Center, and Department of Zoology, Southern Illinois University, Carbondale, IL 62091 (United States); Belden, Jason B. [Department of Zoology, Oklahoma State University, 430 Life Science West, Stillwater, OK 74078 (United States)], E-mail: jbelden@okstate.edu

    2009-01-15

    Despite heavy insecticide usage in urban areas, only a few studies have investigated the impact of current-use insecticides on benthic invertebrates in urban streams. The objective of this study was to measure the presence and concentration of current-use pesticides in sediments of residential streams in central Texas. Additionally, toxicity of these sediments to Hyalella azteca was evaluated. Sediment samples were collected from several sites in urban streams over the course of a year, of which, 66% had greater than one toxic unit (TU) of insecticide. Bifenthrin was the greatest contributor accounting for 65% of the TUs, and sediment toxicity to H. azteca correlated with the magnitude of total insecticides and bifenthrin TUs. The results of this study further raise concerns over the environmental consequences posed by many current-use insecticides, especially pyrethroids, in urban settings. - This study examined the presence of insecticides in Texas stream sediments as a model for evaluating the potential impact of urban insecticide use in the Southern United States.

  8. Effect of zeolite on toxicity of ammonia in freshwater sediments: Implications for toxicity identification evaluation procedures

    Energy Technology Data Exchange (ETDEWEB)

    Besser, J.M.; Ingersoll, C.G. [Geological Survey, Columbia, MO (United States); Leonard, E.N.; Mount, D.R. [Environmental Protection Agency, Duluth, MN (United States). Mid-Continent Ecology Div.

    1998-11-01

    Techniques for reducing ammonia toxicity in freshwater sediments were investigated as part of a project to develop toxicity identification and evaluation (TIE) procedures for whole sediments. Although ammonia is a natural constituent of freshwater sediments, pollution can lead to ammonia concentrations that are toxic to benthic invertebrates, and ammonia can also contribute to the toxicity of sediments that contain more persistent contaminants. The authors investigated the use of amendments of a natural zeolite mineral, clinoptilolite, to reduce concentrations of ammonia in sediment pore water. Zeolites have been widely used for removal of ammonia in water treatment and in aqueous TIE procedures. The addition of granulated zeolite to ammonia-spiked sediments reduced pore-water ammonia concentrations and reduced ammonia toxicity to invertebrates. Amendments of 20% zeolite (v/v) reduced ammonia concentrations in pore water by {ge}70% in spiked sediments with ammonia concentrations typical of contaminated freshwater sediments. Zeolite amendments reduced toxicity of ammonia-spiked sediments to three taxa of benthic invertebrates (Hyalella azteca, Lumbriculus variegatus, and Chironomus tentans), despite their widely differing sensitivity to ammonia toxicity. In contrast, zeolite amendments did not reduce acute toxicity of sediments containing high concentrations of cadmium or copper or reduce concentrations of these metals in pore waters. These studies suggest that zeolite amendments, used in conjunction with toxicity tests with sensitive taxa such as H. azteca, may be an effective technique for selective reduction of ammonia toxicity in freshwater sediments.

  9. Assessing sediment contamination using six toxicity assays

    Directory of Open Access Journals (Sweden)

    Allen G. BURTON Jr.

    2001-08-01

    Full Text Available An evaluation of sediment toxicity at Lake Orta, Italy was conducted to compare a toxicity test battery of 6 assays and to evaluate the extent of sediment contamination at various sediment depths. Lake Orta received excessive loadings of copper and ammonia during the 1900’s until a large remediation effort was conducted in 1989-90 using lime addition. Since that time, the lake has shown signs of a steady recovery of biological communities. The study results showed acute toxicity still exists in sediments at a depth of 5 cm and greater. Assays that detected the highest levels of toxicity were two whole sediment exposures (7 d using Hyalella azteca and Ceriodaphnia dubia. The MicrotoxR assay using pore water was the third most sensitive assay. The Thamnotox, Rototox, Microtox solid phase, and Seed Germination-Root Elongation (pore and solid phase assays showed occasional to no toxicity. Based on similarity of responses and assay sensitivity, the two most useful assays were the C. dubia (or H. azteca and Microtox pore water. These assays were effective at describing sediment toxicity in a weight-of-evidence approach.

  10. Effect of zeolite on toxicity of ammonia in freshwater sediments: Implications for toxicity identification evaluation procedures

    Science.gov (United States)

    Besser, J.M.; Ingersoll, C.G.; Leonard, E.N.; Mount, D.R.

    1998-01-01

    Techniques for reducing ammonia toxicity in freshwater sediments were investigated as part of a project to develop toxicity identification and evaluation (TIE) procedures for whole sediments. Although ammonia is a natural constituent of freshwater sediments, pollution can lead to ammonia concentrations that are toxic to benthic invertebrates, and ammonia can also contribute to the toxicity of sediments that contain more persistent contaminants. We investigated the use of amendments of a natural zeolite mineral, clinoptilolite, to reduce concentrations of ammonia in sediment pore water. Zeolites have been widely used for removal of ammonia in water treatment and in aqueous TIE procedures. The addition of granulated zeolite to ammonia-spiked sediments reduced pore-water ammonia concentrations and reduced ammonia toxicity to invertebrates. Amendments of 20% zeolite (v/v) reduced ammonia concentrations in pore water by ???70% in spiked sediments with ammonia concentrations typical of contaminated freshwater sediments. Zeolite amendments reduced toxicity of ammonia-spiked sediments to three taxa of benthic invertebrates (Hyalella azteca, Lumbriculus variegatus, and Chironomus tentans), despite their widely differing sensitivity to ammonia toxicity. In contrast, zeolite amendments did not reduce acute toxicity of sediments containing high concentrations of cadmium or copper or reduce concentrations of these metals in pore waters. These studies suggest that zeolite amendments, used in conjunction with toxicity tests with sensitive taxa such as H. azteca, may be an effective technique for selective reduction of ammonia toxicity in freshwater sediments.

  11. Ecological bioavailability of permethrin and p,p'-DDT: toxicity depends on type of organic matter resource.

    Science.gov (United States)

    de Perre, Chloé; Trimble, Andrew J; Maul, Jonathan D; Lydy, Michael J

    2014-02-01

    Hydrophobic organic contaminants readily partition from aqueous to organic phases in aquatic systems with past research largely focusing on sediment. However, within many aquatic systems, matrices such as leaf material and detritus are abundant and ecologically important, as they may represent a primary exposure route for aquatic invertebrates. The objectives of the present study were to examine partitioning and toxicity to Hyalella azteca among permethrin and p,p'-DDT contaminated sediment, leaf, and a sediment-leaf mixture. Log organic carbon-water partitioning coefficients ranged from 4.21 to 5.82 for both insecticides, and were greatest within sediment and lowest in coarse leaf material. H. azteca lethal concentrations for 50% of the population (LC50s) ranged from 0.5 to 111μgg(-1) organic carbon, and were dependent on the matrix composition. The variation in sorption and toxicity among matrices common within stream ecosystems suggests that the ecological niche of aquatic organisms may be important for estimating risk of hydrophobic pesticides.

  12. An assessment of the toxicity of phthalate esters to freshwater benthos. 1. Aqueous exposures.

    Science.gov (United States)

    Call, D J; Markee, T P; Geiger, D L; Brooke, L T; VandeVenter, F A; Cox, D A; Genisot, K I; Robillard, K A; Gorsuch, J W; Parkerton, T F; Reiley, M C; Ankley, G T; Mount, D R

    2001-08-01

    Tests were performed with the freshwater invertebrates Hyalella azteca, Chironomus tentans, and Lumbriculus variegatus to determine the acute toxicity of six phthalate esters, including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butylbenzyl phthalate (BBP), di-n-hexyl phthalate (DHP), and di-2-ethylhexyl phthalate (DEHP). It was possible to derive 10-d LC50 (lethal concentration for 50% of the population) values only for the four lower molecular weight esters (DMP, DEP, DBP, and BBP), for which toxicity increased with increasing octanol-water partition coefficient (Kow) and decreasing water solubility. The LC50 values for DMP, DEP, DBP, and BBP were 28.1, 4.21, 0.63, and 0.46 mg/L for H. azteca; 68.2, 31.0, 2.64, and > 1.76 mg/L for C. tentans; and 246, 102, 2.48, and 1.23 mg/L for L. variegatus, respectively. No significant survival reductions were observed when the three species were exposed to either DHP or DEHP at concentrations approximating their water solubilities.

  13. Ensamble de crustáceos bentónicos en un lago salino tropical Benthic crustaceans assemblage in a tropical, saline lake

    Directory of Open Access Journals (Sweden)

    Ma. del Carmen Hernández

    2010-10-01

    Full Text Available El presente trabajo reconoce la composición, estructura y distribución espacial del ensamble de crustáceos bentónicos de Alchichica, un lago salino tropical ubicado en el extremo oriental del altiplano mexicano. El lago presenta una riqueza taxonómica de crustáceos bentónicos compuesta por 1 anfípodo (Hyalella azteca, 1 isópodo (Caecidotea williamsi y 2 ostrácodos (Limnocythere inopinata y Candona sp.. Comparada con otros lagos tropicales, la riqueza de especies es reducida. A pesar de lo anterior, es importante mencionar el grado elevado de endemismo representado por C. williamsi, recientemente descrita para el lago Alchichica; adicionalmente, es factible que tanto Candona como H. azteca sean especies nuevas y endémicas del lago. Los crustáceos bentónicos se distribuyen desde la zona litoral hasta la zona más profunda del lago (62 m con abundancias y riqueza taxonómica variables. Los ostrácodos fueron los crustáceos que con mayor frecuencia se recolectaron en el lago, en la zona litoral, en el talud, y en la zona profunda de la que son habitantes exclusivos. Los anfípodos constituyeron el segundo grupo en abundancia de la zona litoral y talud y estuvieron ausentes en la zona profunda. Los isópodos sólo se encuentran asociados a los depósitos de tufa, hábitat característico del lago que se extiende a lo largo del talud, por lo que con las técnicas de muestreo tradicional empleadas en el presente estudio no fueron capturados. En este ensamble de crustáceos predominan las especies de desarrollo directo y con posiciones tróficas que incluyen componentes herbívoros (H. azteca, omnívoros (C. williamsi y bacterívoros (L. inopinata y Candona sp..This work acknowledges the composition, structure and spatial distribution of the benthic crustaceans assemblage of Alchichica, a tropical saline lake located in the easternmost portion of the Mexican highlands. The benthic crustaceans' assemblage was comprised by 1 amphipod

  14. Tolerance of freshwater test organisms to formulated sediments for use as control materials in whole-sediment toxicity tests

    Energy Technology Data Exchange (ETDEWEB)

    Kemble, N.E.; Dwyer, F.J.; Ingersoll, C.G. [Geological Survey, Columbia, MO (United States). Environmental and Contaminants Research Center; Dawson, T.D. [Integrated Laboratory Systems, Duluth, MN (United States); Norberg-King, T.J. [Environmental Protection Agency, Duluth, MN (United States). Mid-Continent Ecological Div.

    1999-02-01

    A method is described for preparing formulated sediments for use in toxicity testing. Ingredients used to prepare formulated sediments included commercially available silt, clay, sand, humic acid, dolomite, and {alpha}-cellulose (as a source of organic carbon). {alpha}-Cellulose was selected as the source of organic carbon because it is commercially available, consistent from batch to batch, and low in contaminant concentrations. The tolerance of freshwater test organisms to formulated sediments for use as control materials in whole-sediment toxicity testing was evaluated. Sediment exposures were conducted for 10 d with the amphipod Hyalella azteca, the midges Chironomus riparius and C. tentans, and the oligochaete Lumbriculus variegatus and for 28 d with H. azteca. Responses of organisms in formulated sediments was compared with a field-collected control sediment that has routinely been used to determine test acceptability. Tolerance of organisms to formulated sediments was evaluated by determining responses to varying levels of {alpha}-cellulose, to varying levels of grain size, to evaluation of different food types, or to evaluation of different sources of overlying water. In the 10-d exposures, survival of organisms exposed to the formulated sediments routinely met or exceeded the responses of test organisms exposed to the control sediment and routinely met test acceptability criteria required in standard methods. Growth of amphipods and oligochaetes in 10-d exposures with formulated sediment was often less than growth of organisms in the field-collected control sediment. Additional research is needed, using the method employed to prepare formulated sediment, to determine if conditioning formulated sediments before starting 10-d tests would improve the growth of amphipods. In the 28-d exposures, survival of H. azteca was low when reconstituted water was used as the source of overlying water. However, when well water was used as the source of overlying water in

  15. Specifically Designed Constructed Wetlands: A Novel Treatment Approach for Scrubber Wastewater

    Energy Technology Data Exchange (ETDEWEB)

    John H. Rodgers Jr; James W. Castle; Chris Arrington: Derek Eggert; Meg Iannacone

    2005-09-01

    A pilot-scale wetland treatment system was specifically designed and constructed at Clemson University to evaluate removal of mercury, selenium, and other constituents from flue gas desulfurization (FGD) wastewater. Specific objectives of this research were: (1) to measure performance of a pilot-scale constructed wetland treatment system in terms of decreases in targeted constituents (Hg, Se and As) in the FGD wastewater from inflow to outflow; (2) to determine how the observed performance is achieved (both reactions and rates); and (3) to measure performance in terms of decreased bioavailability of these elements (i.e. toxicity of sediments in constructed wetlands and toxicity of outflow waters from the treatment system). Performance of the pilot-scale constructed wetland treatment systems was assessed using two criteria: anticipated NPDES permit levels and toxicity evaluations using two sentinel toxicity-testing organisms (Ceriodaphnia dubia and Pimephales promelas). These systems performed efficiently with varied inflow simulations of FGD wastewaters removing As, Hg, and Se concentrations below NPDES permit levels and reducing the toxicity of simulated FGD wastewater after treatment with the constructed wetland treatment systems. Sequential extraction procedures indicated that these elements (As, Hg, and Se) were bound to residual phases within sediments of these systems, which should limit their bioavailability to aquatic biota. Sediments collected from constructed wetland treatment systems were tested to observe toxicity to Hyalella azteca or Chironomus tetans. Complete survival (100%) was observed for H. azteca in all cells of the constructed wetland treatment system and C. tentans had an average of 91% survival over the three treatment cells containing sediments. Survival and growth of H. azteca and C. tentans did not differ significantly between sediments from the constructed wetland treatment system and controls. Since the sediments of the constructed

  16. Cascading model uncertainty from medium range weather forecasts (10 days) through a rainfall-runoff model to flood inundation predictions within the European Flood Forecasting System (EFFS)

    OpenAIRE

    Pappenberger, F.; K. J. Beven; N. M. Hunter; Bates, P. D.; B. T. Gouweleeuw; Thielen, J.; A. P. J. De De Roo

    2005-01-01

    International audience; The political pressure on the scientific community to provide medium to long term flood forecasts has increased in the light of recent flooding events in Europe. Such demands can be met by a system consisting of three different model components (weather forecast, rainfall-runoff forecast and flood inundation forecast) which are all liable to considerable uncertainty in the input, output and model parameters. Thus, an understanding of cascaded uncertainties is a necessa...

  17. A 10-Day Developmental Voyage: Converging Evidence from Three Studies Showing that Self-Esteem May Be Elevated and Maintained without Negative Outcomes

    Science.gov (United States)

    Kafka, S.; Hunter, J. A.; Hayhurst, J.; Boyes, M.; Thomson, R. L.; Clarke, H.; Grocott, A. M.; Stringer, M.; O'Brien, K. S.

    2012-01-01

    Empirical evidence shows that educational experiences in the context of the outdoors lead to elevated self-esteem. Although elevated self-esteem is widely assumed to promote beneficial outcomes, recent evidence suggests that elevated self-esteem may also facilitate a variety of negative outcomes (i.e., increased prejudice, aggression, drug and…

  18. A 10-Day Developmental Voyage: Converging Evidence from Three Studies Showing that Self-Esteem May Be Elevated and Maintained without Negative Outcomes

    Science.gov (United States)

    Kafka, S.; Hunter, J. A.; Hayhurst, J.; Boyes, M.; Thomson, R. L.; Clarke, H.; Grocott, A. M.; Stringer, M.; O'Brien, K. S.

    2012-01-01

    Empirical evidence shows that educational experiences in the context of the outdoors lead to elevated self-esteem. Although elevated self-esteem is widely assumed to promote beneficial outcomes, recent evidence suggests that elevated self-esteem may also facilitate a variety of negative outcomes (i.e., increased prejudice, aggression, drug and…

  19. Influence of a 10-Day Mimic of Our Ancient Lifestyle on Anthropometrics and Parameters of Metabolism and Inflammation : The "Study of Origin"

    NARCIS (Netherlands)

    Pruimboom, Leo; Ruiz-Nunez, Begona; Raison, Charles L.; Muskiet, Frits A. J.

    2016-01-01

    Chronic low-grade inflammation and insulin resistance are intimately related entities that are common to most, if not all, chronic diseases of affluence. We hypothesized that a short-term intervention based on "ancient stress factors" may improve anthropometrics and clinical chemical indices. We exe

  20. [THE EFFECTIVENESS OF A 10-DAY DRUG THERAPY IN CHILDREN WITH CHRONIC GASTRODUODENAL PATHOLOGY ASSOCIATED WITH CAGA-POSITIVE STRAINS OF HELICOBACTER PYLORI].

    Science.gov (United States)

    Dudnyk, V M; Rudenko, G M

    2015-01-01

    The results of triple Helicobacter-therapy (omeprazole, amoxicillin, nifuratel) in the treatment of chronic gastroduodenal pathology in children depending on the duration of it's use. The effectiveness of drug therapy was evaluated in terms of eradication of Helicobacter pylori and dynamics of pain, dyspeptic syndrome and astenovegetative syndrome.

  1. Influence of a 10-Day Mimic of Our Ancient Lifestyle on Anthropometrics and Parameters of Metabolism and Inflammation : The "Study of Origin"

    NARCIS (Netherlands)

    Pruimboom, Leo; Ruiz-Nunez, Begona; Raison, Charles L.; Muskiet, Frits A. J.

    2016-01-01

    Chronic low-grade inflammation and insulin resistance are intimately related entities that are common to most, if not all, chronic diseases of affluence. We hypothesized that a short-term intervention based on "ancient stress factors" may improve anthropometrics and clinical chemical indices. We

  2. Laboratory toxicity and benthic invertebrate field colonization of Upper Columbia River sediments: Finding adverse effects using multiple lines of evidence

    Science.gov (United States)

    Fairchild, J.F.; Kemble, N.E.; Allert, A.L.; Brumbaugh, W.G.; Ingersoll, C.G.; Dowling, B.; Gruenenfelder, C.; Roland, J.L.

    2012-01-01

    From 1930 to 1995, the Upper Columbia River (UCR) of northeast Washington State received approximately 12 million metric tons of smelter slag and associated effluents from a large smelter facility located in Trail, British Columbia, approximately 10 km north of the United States–Canadian border. Studies conducted during the past two decades have demonstrated the presence of toxic concentrations of heavy metals in slag-based sandy sediments, including cadmium, copper, zinc, and lead in the UCR area as well as the downstream reservoir portion of Lake Roosevelt. We conducted standardized whole-sediment toxicity tests with the amphipod Hyalella azteca (28-day) and the midge Chironomus dilutus (10-day) on 11 samples, including both UCR and study-specific reference sediments. Metal concentrations in sediments were modeled for potential toxicity using three approaches: (1) probable effects quotients (PEQs) based on total recoverable metals (TRMs) and simultaneously extracted metals (SEMs); (2) SEMs corrected for acid-volatile sulfides (AVS; i.e., ΣSEM - AVS); and (3) ΣSEM - AVS normalized to the fractional organic carbon (foc) (i.e., ΣSEM - AVS/foc). The most highly metal-contaminated sample (ΣPEQTRM = 132; ΣPEQSEM = 54; ΣSEM - AVS = 323; and ΣSEM - AVS/foc = 64,600 umol/g) from the UCR was dominated by weathered slag sediment particles and resulted in 80% mortality and 94% decrease in biomass of amphipods; in addition, this sample significantly decreased growth of midge by 10%. The traditional ΣAVS - SEM, uncorrected for organic carbon, was the most accurate approach for estimating the effects of metals in the UCR. Treatment of the toxic slag sediment with 20% Resinex SIR-300 metal-chelating resin significantly decreased the toxicity of the sample. Samples ΣSEM - AVS > 244 was not toxic to amphipods or midge in laboratory testing, indicating that this value may be an approximate threshold for effects in the UCR. In situ benthic invertebrate colonization

  3. Lista de crustáceos distribuidos en troncos hundidos en el humedal tropical Pantanos de Centla, al sur del golfo de México List of crustaceans distributed in submerged woody debris in the tropical wetlands of Pantanos de Centla, southern Gulf of Mexico

    Directory of Open Access Journals (Sweden)

    Hugo Montalvo-Urgel

    2010-10-01

    Full Text Available En las comunidades acuáticas, la complejidad del hábitat modifica la dinámica y la estructura, ya que la diversidad y abundancia aumentan conforme se incrementan las estructuras físicas emergentes del sustrato, como los troncos hundidos, que son sitios de refugio, alimentación y reproducción de la fauna asociada a esos hábitats. En 18 lagunas de Pantanos de Centla, Tabasco, donde se encontraron troncos hundidos, se realizaron 2 muestros manuales en la temporada de máxima inundación y 1 en la de mínima inundación. Se capturaron 1 228 crustáceos que pertenecen a 4 órdenes, 11 familias, 11 géneros y 13 especies, de los cuales los malacostracos predominaron con 12 especies. Las 13 especies de crustáceos registradas en este trabajo representaron el 17% de la carcinofauna capturada en los ecosistemas limnéticos del estado de Tabasco. El anfípodo Hyalella azteca fue numéricamente la especie dominante. La distribución de Balanus improvisus, Uhlorchestia ulheri, Platychirograpsus spectabilis, Armases cinereum y Goniopsis cruentata estuvo restringida principalmente a la zona de influencia marina. Balanus improvisus y Sphaeroma terebrans fueron las únicas especies sésiles y taladradoras recolectadas. Para las restantes 11 especies de crustáceos, los troncos hundidos también son un hábitat alternativo.The dynamics and structure of aquatic communities are affected by the habitat complexity as diversity and abundance increase with the availability of structured habitats such as coarse woody debris that provides sites used for refuge, feeding and reproduction. Manual sampling of the fauna associated with this habitat was carried out twice during the season of maximum floods and once during minimum flooding, in 18 lagoons of Pantanos de Centla with coarse woody debris. The 1 228 crustaceans collected belong to 4 orders, 11 families, 11 genera and 13 species, among which malacostracans dominated with 12 species. The 13 species of

  4. OMEGAHAB-XP a bioregenerative aquatic life support system designed to be used in Bion-M1 long term space flight

    Science.gov (United States)

    Hilbig, Reinhard; Lebert, Michael

    The OmegaHab XP Experiment will be based on the OmegaHab system successfully flown in the context of the FOTON M3 mission. OmegaHab XP -a refurbished OmegaHab for a long term mission -is in general assembled from four parts: an algae compartment, a nutrition com-partment for higher plants and crustaceens, a fish compartment and a filter compartment with biodegradant bacterias. The algae compartment (Euglena gracilis; unicellular, photosynthetic flagellate) will be illuminated with photosynthetic active radiation and will produce oxygen. The photosynthetic process also consumes carbon dioxide and if available ammonia. In addi-tion, nitrate will be taken up by the algae and by this means removed from the system. Via a gas-permeable membrane (gas/ion exchanger) the produced oxygen will be transported in a separate fish compartment. The metabolism of the fish will produce carbon dioxide and nitro-genic components. These components as well as the carbon dioxide will be transported back in the algae compartment and subsequently used by the algae. The transport of the components is enhanced by a counter flow inside the gas/ion exchanger driven by a pump. In addition, a filter system is installed which removes debris as well as ammonia by means of ammonia metabolizing bacteria. The nutrition compartment with higher plants and the crustaceans (e.g. Hyalella azteca; flown successfully aboard shuttles) builds the basis of this multi-trophic sys-tem. Hyalella azteca can reproduce in an adequate amount to replace external fish nutrition for Oreochromis mossambicus in large parts. The fish compartment is divided into two chambers: a hatchery chamber for larval fishes and an chamber for subadult Oreochromis mossambicus. The system is fully automatic and measures and stores all house-keeping data internally. These house-keeping data include light, temperature, acceleration and oxygen as well as many system related parameters. By means of Peltier-elements the system can be

  5. Ecotoxicological assessment of the pharmaceutical fluoxetine hydrochloride and the surfactant dodecyl sodium sulfate after their submission to ionizing radiation treatment; Avaliacao ecotoxicologica do farmaco cloridrato de fluoxetina e do surfactante dodecil sulfato de sodio quando submetidos a tratamento por radiacao ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Dymes Rafael Alves dos

    2011-07-01

    The use of pharmaceuticals and personal care products and the consequent and continuous input of this substances in the environment generates an increasing need to investigate the presence, behavior and the effects on aquatic biota, as well as new ways to treat effluents containing such substances. Fluoxetine hydrochloride is an active ingredient used in the treatment of depressive disorders and anxiety. As the surfactant sodium dodecyl sulfate is present in many cleaning and personal care products. The present study aimed on assessing the acute toxicity of fluoxetine hydrochloride, sodium dodecyl sulfate and the mixture of both to the aquatic organisms Hyalella azteca, Daphnia similis and Vibrio ficheri. Reducing the toxicity of fluoxetine and the mixture after treatment with ionizing radiation from industrial electron beam accelerator has also been the focus of this study. For Daphnia similis the average values of CE50-4{sub 8h} found for the non-irradiated drug, surfactant and mixture were 14.4 %, 9.62 % and 13.8 %, respectively. After irradiation of the substances, the dose 5 kGy proved itself to be the most effective dose for the treatment of the drug and the mixture as it was obtained the mean values for CE50{sub 48h} 84.60 % and > 90 %, respectively. For Hyalella azteca the acute toxicity tests were performed for water column with duration of 96 hours, the mean values for CE50{sub 96h} found for the drug, the surfactant and the mixture non-irradiated were 5.63 %, 19.29 %, 6.27 %, respectively. For the drug fluoxetine and the mixture irradiated with 5 kGy, it was obtained 69.57 % and 77.7 %, respectively. For Vibrio ficheri the acute toxicity tests for the untreated drug and the drug irradiated with 5 kGy it was obtained CE50{sub 15min} of 6.9 % and 32.88 % respectively. These results presented a reduction of the acute toxicity of the test-substances after irradiation. (author)

  6. Chronic toxicity of azoxystrobin to freshwater amphipods, midges, cladocerans, and mussels in water-only exposures

    Science.gov (United States)

    Kunz, James L.; Ingersoll, Christopher G.; Smalling, Kelly; Elskus, Adria; Kuivila, Kathryn

    2017-01-01

    Understanding the effects of fungicides on nontarget organisms at realistic concentrations and exposure durations is vital for determining potential impacts on aquatic ecosystems. Environmental concentrations of the fungicide azoxystrobin have been reported up to 4.6 μg/L in the United States and 30 μg/L in Europe. The objective of the present study was to evaluate the chronic toxicity of azoxystrobin in water-only exposures with an amphipod (Hyalella azteca; 42-d exposure), a midge (Chironomus dilutus; 50-d exposure), a cladoceran (Ceriodaphnia dubia; 7-d exposure), and a unionid mussel (Lampsilis siliquoidea; 28-d exposure) at environmentally relevant concentrations. The potential photo-enhanced toxicity of azoxystrobin accumulated by C. dubiaand L. siliquoidea following chronic exposures to azoxystrobin was also evaluated. The 20% effect concentrations (EC20s) based on the most sensitive endpoint were 4.2 μg/L for H. aztecareproduction, 12 μg/L for C. dubia reproduction and C. dilutus emergence, and >28 μg/L for L. siliquoidea. Hyalella azteca was more sensitive to azoxystrobin compared with the other 3 species in the chronic exposures. No photo-enhanced toxicity was observed for either C. dubia or L. siliquoidea exposed to ultraviolet light in control water following azoxystrobin tests. The results of the present study indicate chronic effects of azoxystrobin on 3 of 4 invertebrates tested at environmentally relevant concentrations. The changes noted in biomass and reproduction have the potential to alter the rate of ecological processes driven by aquatic invertebrates. Environ Toxicol Chem 2017;9999:1–8. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

  7. Chronic toxicity of nickel-spiked freshwater sediments: variation in toxicity among eight invertebrate taxa and eight sediments

    Science.gov (United States)

    Besser, John M.; Brumbaugh, William G.; Ingersoll, Christopher G.; Ivey, Chris D.; Kunz, James L.; Kemble, Nile E.; Schlekat, Christian E.; Garman, Emily R.

    2013-01-01

    This study evaluated the chronic toxicity of Ni-spiked freshwater sediments to benthic invertebrates. A 2-step spiking procedure (spiking and sediment dilution) and a 2-stage equilibration period (10 wk anaerobic and 1 wk aerobic) were used to spike 8 freshwater sediments with wide ranges of acid-volatile sulfide (AVS; 0.94–38 µmol/g) and total organic carbon (TOC; 0.42–10%). Chronic sediment toxicity tests were conducted with 8 invertebrates (Hyalella azteca, Gammarus pseudolimnaeus, Chironomus riparius, Chironomus dilutus, Hexagenia sp., Lumbriculus variegatus, Tubifex tubifex, and Lampsilis siliquoidea) in 2 spiked sediments. Nickel toxicity thresholds estimated from species-sensitivity distributions were 97 µg/g and 752 µg/g (total recoverable Ni; dry wt basis) for sediments with low and high concentrations of AVS and TOC, respectively. Sensitive species were tested with 6 additional sediments. The 20% effect concentrations (EC20s) for Hyalella and Gammarus, but not Hexagenia, were consistent with US Environmental Protection Agency benchmarks based on Ni in porewater and in simultaneously extracted metals (SEM) normalized to AVS and TOC. For Hexagenia, sediment EC20s increased at less than an equimolar basis with increased AVS, and toxicity occurred in several sediments with Ni concentrations in SEM less than AVS. The authors hypothesize that circulation of oxygenated water by Hexagenia led to oxidation of AVS in burrows, creating microenvironments with high Ni exposure. Despite these unexpected results, a strong relationship between Hexagenia EC20s and AVS could provide a basis for conservative site-specific sediment quality guidelines for Ni.

  8. Integrated assessment of the impacts of agricultural drainwater in the Salinas River (California, USA)

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, B.S.; Hunt, J.W.; Phillips, B.M.; Nicely, P.A.; Vlaming, V. de; Connor, V.; Richard, N.; Tjeerdema, R.S

    2003-08-01

    Invertebrate mortality was correlated with levels of water and sediment contaminatioin in the Salinas River. - The Salinas River is the largest of the three rivers that drain into the Monterey Bay National Marine Sanctuary in central California. Large areas of this watershed are cultivated year-round in row crops and previous laboratory studies have demonstrated that acute toxicity of agricultural drainwater to Ceriodaphnia dubia is caused by the organophosphate (OP) pesticides chlorpyrifos and diazinon. In the current study, we used a combination of ecotoxicologic tools to investigate incidence of chemical contamination and toxicity in waters and sediments in the river downstream of a previously uncharacterized agricultural drainage creek system. Water column toxicity was investigated using a cladoceran C. dubia while sediment toxicity was investigated using an amphipod Hyalella azteca. Ecological impacts of drainwater were investigated using bioassessments of macroinvertebrate community structure. The results indicated that Salinas River water downstream of the agricultural drain is acutely toxic to Ceriodaphnia, and toxicity to this species was highly correlated with combined toxic units (TUs) of chlorpyrifos and diazinon. Laboratory tests were used to demonstrate that sediments in this system were acutely toxic to H. azteca, which is a resident genus. Macroinvertebrate community structure was moderately impacted downstream of the agricultural drain input. While the lowest macroinvertebrate abundances were measured at the station demonstrating the greatest water column and sediment toxicity and the highest concentrations of pesticides, macroinvertebrate metrics were more significantly correlated with bank vegetation cover than any other variable. Results of this study suggest that pesticide pollution is the likely cause of laboratory-measured toxicity in the Salinas River samples and that this factor may interact with other factors to impact the

  9. A site-specific ecological risk assessment for corn-associated insecticides.

    Science.gov (United States)

    Whiting, Sara A; Lydy, Michael J

    2015-07-01

    A site-specific ecological risk assessment (ERA) was conducted to examine the simultaneous use of genetically modified corn (Bt corn) with a neonicotinoid seed coating, clothianidin, and use of a granular insecticide, tefluthrin, to protect crops from pest damage. A field study was conducted on site, and exposure data from the literature were summarized to determine the matrices and exposure concentrations that nontarget species could typically experience within an agricultural ecosystem. To determine ecological effects on nontarget species, acute toxicity bioassays were conducted on earthworms (Eisenia fetida), amphipods (Hyalella azteca), and Elmid riffle beetle larvae (Ancyronyx spp.) in which the test species were exposed to single insecticides as well as the mixture of the 3 insecticides. In the risk characterization section of the ERA, stressor-response profiles for each species tested were compared with field distributions of the insecticides, and a margin of safety at the 10th percentile (MOS10) was calculated to estimate risk. No acute toxicity was observed in any of the 3 nontarget species after exposure to senescent Bt corn leaf tissue. Large MOS10 values were calculated for clothianidin to the nontarget species. When bioassays were compared with tefluthrin field distributions, very low MOS10 values were calculated for earthworms (0.06) and H. azteca (0.08) because the environmental concentrations often exceeded the stressor-response profile. No increased toxicity was observed when nontarget species were exposed to a mixture of the 3 insecticides. In summary, the genetically modified corn insecticidal proteins and clothianidin were not found at environmental concentrations exceeding benchmark values for ecological effects, but tefluthrin was consistently detected in the environment at levels that could be causing toxicity to nontarget species, especially if this pyrethroid is able to travel off site. © 2015 SETAC.

  10. Pyrethroid insecticides in urban salmon streams of the Pacific Northwest

    Energy Technology Data Exchange (ETDEWEB)

    Weston, D.P., E-mail: dweston@berkeley.edu [Department of Integrative Biology, University of California, 3060 Valley Life Sciences Bldg., Berkeley, CA 94720-3140 (United States); Asbell, A.M., E-mail: aasbell@berkeley.edu [Department of Integrative Biology, University of California, 3060 Valley Life Sciences Bldg., Berkeley, CA 94720-3140 (United States); Hecht, S.A., E-mail: scott.hecht@noaa.gov [NOAA Fisheries, Office of Protected Resources, 510 Desmond Drive S.E., Lacey, WA 98503 (United States); Scholz, N.L., E-mail: nathaniel.scholz@noaa.gov [NOAA Fisheries, Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112 (United States); Lydy, M.J., E-mail: mlydy@siu.edu [Fisheries and Illinois Aquaculture Center and Department of Zoology, Southern Illinois University, 171 Life Sciences II, Carbondale, IL 62901 (United States)

    2011-10-15

    Urban streams of the Pacific Northwest provide spawning and rearing habitat for a variety of salmon species, and food availability for developing salmon could be adversely affected by pesticide residues in these waterbodies. Sediments from Oregon and Washington streams were sampled to determine if current-use pyrethroid insecticides from residential neighborhoods were reaching aquatic habitats, and if they were at concentrations acutely toxic to sensitive invertebrates. Approximately one-third of the 35 sediment samples contained measurable pyrethroids. Bifenthrin was the pyrethroid of greatest concern with regards to aquatic life toxicity, consistent with prior studies elsewhere. Toxicity to Hyalella azteca and/or Chironomus dilutus was found in two sediment samples at standard testing temperature (23 deg. C), and in one additional sample at a more environmentally realistic temperature (13 deg. C). Given the temperature dependency of pyrethroid toxicity, low temperatures typical of northwest streams can increase the potential for toxicity above that indicated by standard testing protocols. - Highlights: > Salmon-bearing creeks can be adversely impacted by insecticides from urban runoff. > Pyrethroid insecticides were found in one-third of the creeks in Washington and Oregon. > Two creeks contained concentrations acutely lethal to sensitive invertebrates. > Bifenthrin was of greatest concern, though less than in prior studies. > Standard toxicity testing underestimates the ecological risk of pyrethroids. - Pyrethroid insecticides are present in sediments of urban creeks of Oregon and Washington, though less commonly than in studies elsewhere in the U.S.

  11. Assessment of nonpoint-source runoff in a stream using in situ and laboratory approaches

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, K.A.; Burton, G.A. Jr.

    1999-12-01

    Anthropogenic activities that change a watershed can cause adverse impacts to receiving water. Agricultural and urban runoff are the two leading causes of surface-water impairment in the US. When assessing pollutant sources and their effects on aquatic ecosystems, and prior to implementing source controls, it is necessary to define the systems stressors and receptors of exposure. Toxicity assays are a key component to integrative assessments that include habitat (physical), chemical, and indigenous community characterization. Traditional toxicity assay methods and the use of water-quality criteria are often inappropriate because of exposure design and effect assumptions. Hyalella azteca and Chironomus tentans were exposed in situ for varying time periods during both low- and high-flow conditions to determine the effect of urban and agricultural runoff. Short-term chronic and acute toxicity of urban and agricultural runoff was then measured in the laboratory and related to in situ test results. Nonpoint-source (NPS) runoff from urban areas was often more acutely toxic to organisms in the laboratory as compared to in situ results. Conversely, toxicity to the organisms was greater at the agricultural site during in situ exposures when compared to laboratory. In situ assays were an essential and integral component of NPS runoff assessments. They provided unique information that complemented laboratory toxicity, habitat, benthic community, and physicochemical characterizations.

  12. Local impacts of coal mines and power plants across Canada. II. Metals, organics and toxicity in sediments

    Energy Technology Data Exchange (ETDEWEB)

    Cheam, V.; Reynoldson, T.; Garbai, G.; Rajkumar, J.; Milani, D. [Environment of Canada, Burlington, ON (Canada). National Water Research Institute

    2000-07-01

    A Canada-wide survey was undertaken to study local impacts of coal mines and coal-fired electrical generating stations. The first part dealt with thallium in waters and sediments. This, Part II, deals with metals and organics in sediments as well as sediment toxicity to four different organisms. Several elevated metal and PAH concentrations as well as high toxicity (based on biological sediment guidelines) were observed compared to uncontaminated sites. Based on Ontario's sediment guidelines, most of the studied sediments fell in the 'marginally to significantly polluted' category of sediment quality, although two belonged to the 'grossly polluted' class due to the extremely high concentrations of some metals. The observed diversity of PAHs and near-unity carbon preference indices indicate non-biological origins of the studied sediments. In this initial study, four different organisms, Chironomus riparius, Hyalella azteca, Hexagenia spp. (Hexagenia limbata) and Tubifex tubifex were used to determine sediment toxicity, which showed 50% of the tested sites were highly stressed.

  13. Use of toxicity identification evaluations to determine the pesticide mitigation effectiveness of on-farm vegetated treatment systems

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, John [Department of Environmental Toxicology, University of California, Davis, CA (United States); Department of Environmental Studies, University of California, Santa Cruz, CA (United States); Marine Pollution Studies Laboratory, Granite Canyon, 34500 Highway 1, Monterey, CA 93940 (United States)], E-mail: jwhunt@ucdavis.edu; Anderson, Brian [Department of Environmental Toxicology, University of California, Davis, CA (United States); Marine Pollution Studies Laboratory, Granite Canyon, 34500 Highway 1, Monterey, CA 93940 (United States)], E-mail: anderson@ucdavis.edu; Phillips, Bryn [Department of Environmental Toxicology, University of California, Davis, CA (United States); Marine Pollution Studies Laboratory, Granite Canyon, 34500 Highway 1, Monterey, CA 93940 (United States)], E-mail: bmphillips@ucdavis.edu; Tjeerdema, Ron [Department of Environmental Toxicology, University of California, Davis, CA (United States); Marine Pollution Studies Laboratory, Granite Canyon, 34500 Highway 1, Monterey, CA 93940 (United States)], E-mail: rstjeerdema@ucdavis.edu; Largay, Bryan [Largay Hydrologic Sciences, LLC, 160 Farmer Street Felton, CA 95018-9416 (United States)], E-mail: bryan.largay@sbcglobal.net; Beretti, Melanie [Resources Conservation District of Monterey County, 744-A La Guardia Street, Salinas, CA 93905 (United States)], E-mail: beretti.melanie@rcdmonterey.org; Bern, Amanda [California Regional Water Quality Control Board, Central Coast Region, 895 Aerovista Place, Suite 101, San Luis Obispo, CA 93401 (United States)], E-mail: abern@waterboards.ca.gov

    2008-11-15

    Evidence of ecological impacts from pesticide runoff has prompted installation of vegetated treatment systems (VTS) along the central coast of California, USA. During five surveys of two on-farm VTS ponds, 88% of inlet and outlet water samples were toxic to Ceriodaphnia dubia. Toxicity identification evaluations (TIEs) indicated water toxicity was caused by diazinon at VTS-1, and chlorpyrifos at VTS-2. Diazinon levels in VTS-1 were variable, but high pulse inflow concentrations were reduced through dilution. At VTS-2, chlorpyrifos concentrations averaged 52% lower at the VTS outlet than at the inlet. Water concentrations of most other pesticides averaged 20-90% lower at VTS outlets. All VTS sediment samples were toxic to amphipods (Hyalella azteca). Sediment TIEs indicated toxicity was caused by cypermethrin and lambda-cyhalothrin at VTS-1, and chlorpyrifos and permethrin at VTS-2. As with water, sediment concentrations were lower at VTS outlets, indicating substantial reductions in farm runoff pesticide concentrations. - Toxicity identification evaluations identified key pesticides in agricultural runoff, and their concentrations were reduced by farmer-installed vegetated treatment systems.

  14. Evidence of lead biomagnification in invertebrate predators from laboratory and field experiments

    Energy Technology Data Exchange (ETDEWEB)

    Rubio-Franchini, Isidoro [Departamento de Quimica, Centro de Ciencias Basicas, Universidad Autonoma de Aguascalientes, Avenida Universidad 940, CP 20131 Aguascalientes (Mexico); Rico-Martinez, Roberto, E-mail: rrico@correo.uaa.mx [Departamento de Quimica, Centro de Ciencias Basicas, Universidad Autonoma de Aguascalientes, Avenida Universidad 940, CP 20131 Aguascalientes (Mexico)

    2011-07-15

    This report includes atomic absorption data from water column, elutriates and zooplankton that demonstrate that lead biomagnifies at El Niagara reservoir, Mexico. Results include field data (bioaccumulation factors) (BAFs) and laboratory data (bioconcentration factors) (BCFs). Two findings: high BAFs for invertebrate predator like Acanthocyclops robustus, Asplanchna brightwellii, Culex sp. larvae, and Hyalella azteca, compared to grazer species Moina micrura and Simocephalus vetulus; low BCF's found for some predators, suggested that lead biomagnifications were taking place. The presence of Moina micrura in the gut of Asplanchna allowed us to design experiments where A. brightwellii was fed lead-exposed M. micrura neonates. The BAF of Asplanchna was 123,684, BCF was 490. Asplanchna individuals fed exposed Moina had 13.31 times more lead than Asplanchna individuals just exposed 48-h to lead, confirming that lead biomagnification occurs. Results of two fish species showed no lead biomagnification, suggesting that lead biomagnification might be restricted to invertebrate predators. - Highlights: > Study shows lead biomagnification evidence in reservoirs where top predators are invertebrates. > Study discusses why in previous studies lead biomagnifications were not detected. > Evidence of biomagnification comes from field and laboratory studies. - This study shows evidence (from field and laboratory experiments) of lead biomagnification in a freshwater reservoir where the main predators are invertebrates.

  15. Environmental modeling and exposure assessment of sediment-associated pyrethroids in an agricultural watershed.

    Directory of Open Access Journals (Sweden)

    Yuzhou Luo

    Full Text Available Synthetic pyrethroid insecticides have generated public concerns due to their increasing use and potential effects on aquatic ecosystems. A modeling system was developed in this study for simulating the transport processes and associated sediment toxicity of pyrethroids at coupled field/watershed scales. The model was tested in the Orestimba Creek watershed, an agriculturally intensive area in California' Central Valley. Model predictions were satisfactory when compared with measured suspended solid concentration (R(2 = 0.536, pyrethroid toxic unit (0.576, and cumulative mortality of Hyalella azteca (0.570. The results indicated that sediment toxicity in the study area was strongly related to the concentration of pyrethroids in bed sediment. Bifenthrin was identified as the dominant contributor to the sediment toxicity in recent years, accounting for 50-85% of predicted toxicity units. In addition, more than 90% of the variation on the annual maximum toxic unit of pyrethroids was attributed to precipitation and prior application of bifenthrin in the late irrigation season. As one of the first studies simulating the dynamics and spatial variability of pyrethroids in fields and instreams, the modeling results provided useful information on new policies to be considered with respect to pyrethroid regulation. This study suggested two potential measures to efficiently reduce sediment toxicity by pyrethroids in the study area: [1] limiting bifenthrin use immediately before rainfall season; and [2] implementing conservation practices to retain soil on cropland.

  16. Catchment liming creates recolonization opportunity for sensitive invertebrates in a smelter impacted landscape

    Directory of Open Access Journals (Sweden)

    John M. Gunn

    2016-04-01

    Full Text Available The response of a sensitive indicator species to the effects of catchment liming was assessed in a lake severely impacted by atmospheric emissions from a metal smelter in Sudbury, Canada. The lake chemistry recovered following the closure of the local smelter and major reductions (approximately 95% in acid and metal emissions from other area smelters, leading to recolonization of the lake with fish and other biota. However, the littoral macrobenthos community remain severely impoverished. The catchment liming sustained improved stream water quality for 20 years after the initial aerial treatment and created a littoral zone hot spot for the recolonization of Hyalella azteca. Colonization at delta sites of untreated catchment drainage areas, in the same lake, were low and highly variable, and these sites appeared to be impacted from soil erosion and episodic release of acid and metals. This study demonstrated the need to both reduce air pollutants and to conduct land reclamation in severely damaged watersheds, before lake ecosystems themselves can be fully recovered.

  17. Toxicity of carbon nanotubes to freshwater aquatic invertebrates

    Science.gov (United States)

    Mwangi, Joseph N.; Wang, Ning; Ingersoll, Christopher G.; Hardesty, Doug K.; Brunson, Eric L.; Li, Hao; Deng, Baolin

    2012-01-01

    Carbon nanotubes (CNTs) are hydrophobic in nature and thus tend to accumulate in sediments if released into aquatic environments. As part of our overall effort to examine the toxicity of carbon-based nanomaterials to sediment-dwelling invertebrates, we have evaluated the toxicity of different types of CNTs in 14-d water-only exposures to an amphipod (Hyalella azteca), a midge (Chironomus dilutus), an oligochaete (Lumbriculus variegatus), and a mussel (Villosa iris) in advance of conducting whole-sediment toxicity tests with CNTs. The results of these toxicity tests conducted with CNTs added to water showed that 1.00g/L (dry wt) of commercial sources of CNTs significantly reduced the survival or growth of the invertebrates. Toxicity was influenced by the type and source of the CNTs, by whether the materials were precleaned by acid, by whether sonication was used to disperse the materials, and by species of the test organisms. Light and electron microscope imaging of the surviving test organisms showed the presence of CNTs in the gut as well as on the outer surface of the test organisms, although no evidence was observed to show penetration of CNTs through cell membranes. The present study demonstrated that both the metals solubilized from CNTs such as nickel and the "metal-free" CNTs contributed to the toxicity.

  18. Using a triad approach in the assessment of hazardous waste site leaching from a Superfund site to an adjacent stream

    Energy Technology Data Exchange (ETDEWEB)

    Leppanen, C.J. [Univ. of Maine, Orono, ME (United States). Dept. of Biochemistry, Microbiology, and Molecular Biology; Blanner, P.M.; Allan, R.S.; Maier, K.J. [Univ. of Memphis, TN (United States); Benson, W.H. [Univ. of Mississippi, University, MS (United States)

    1998-10-01

    A triad approach was used in the evaluation of sediment in the Wolf River adjacent to the North Hollywood Dump, a federally listed Superfund site. Chemical analyses were done for 18 organochlorine pesticides, 21 polychlorinated biphenyl (PCB) congeners, and 10 metals. Sediment toxicity was evaluated with freshwater invertebrates. Chironomus tentans and Hyalella azteca. Benthic macroinvertebrate diversity and abundance were assessed with a family-level biotic index. Mean Al, Ba, Cd, Cu, Fe, Ni, Pb, and Zn concentrations were significantly higher in sediments collected in the spring. Both spring and fall sediments exhibited toxicity downstream from, adjacent to, and upstream from the dump, with toxicity significantly higher in fall sediments; however, a consistent trend was not observed. Toxicity was typically greater in the fall, and metal concentrations were typically higher in spring sediments, suggesting that metals were not responsible for the toxicity. Sediment-associated organochlorine pesticide and PCB congener concentrations were all below detectable limits, suggesting that these potential contaminants are not contributing to the observed toxicity. No differences were found in benthic macroinvertebrate community structure, which was composed of predominantly pollution-tolerant families, among seasons or river reaches, which appear to be limited by the physical characteristics of the river. Sediments in urban reaches of the Wolf River appear to be degraded; the North Hollywood Dump cannot be isolated as a source of toxicity in this study. In situ testing, sediment toxicity identification and evaluation testing, acid-volatile sulfide analyses, or artificial substrate work would be appropriate to follow.

  19. Toxicity of sediments from lead-zinc mining areas to juvenile freshwater mussels (Lampsilis siliquoidea) compared to standard test organisms.

    Science.gov (United States)

    Besser, John M; Ingersoll, Christopher G; Brumbaugh, William G; Kemble, Nile E; May, Thomas W; Wang, Ning; MacDonald, Donald D; Roberts, Andrew D

    2015-03-01

    Sediment toxicity tests compared chronic effects on survival, growth, and biomass of juvenile freshwater mussels (28-d exposures with Lampsilis siliquoidea) to the responses of standard test organisms-amphipods (28-d exposures with Hyalella azteca) and midges (10-d exposures with Chironomus dilutus)-in sediments from 2 lead-zinc mining areas: the Tri-State Mining District and Southeast Missouri Mining District. Mussel tests were conducted in sediments sieved to toxic responses (reduced 10% or more relative to reference sites) in Tri-State sediments was greatest for amphipod survival (25% of samples), midge biomass (20%), and mussel survival (14%). In southeast Missouri sediments, the frequency of highly toxic samples was greatest for mussel biomass (25%) and amphipod biomass (13%). Thresholds for metal toxicity to mussels, expressed as hazard quotients based on probable effect concentrations, were lower for southeast Missouri sediments than for Tri-State sediments. Southeast Missouri sites with toxic sediments had 2 or fewer live mussel taxa in a concurrent mussel population survey, compared with 7 to 26 taxa at reference sites. These results demonstrate that sediment toxicity tests with juvenile mussels can be conducted reliably by modifying existing standard methods; that the sensitivity of mussels to metals can be similar to or greater than standard test organisms; and that responses of mussels in laboratory toxicity tests are consistent with effects on wild mussel populations.

  20. Ecological impacts of lead mining on Ozark streams: toxicity of sediment and pore water.

    Science.gov (United States)

    Besser, John M; Brumbaugh, William G; Allert, Ann L; Poulton, Barry C; Schmitt, Christopher J; Ingersoll, Christopher G

    2009-02-01

    We studied the toxicity of sediments downstream of lead-zinc mining areas in southeast Missouri, using chronic sediment toxicity tests with the amphipod, Hyalella azteca, and pore-water toxicity tests with the daphnid, Ceriodaphnia dubia. Tests conducted in 2002 documented reduced survival of amphipods in stream sediments collected near mining areas and reduced survival and reproduction of daphnids in most pore waters tested. Additional amphipod tests conducted in 2004 documented significant toxic effects of sediments from three streams downstream of mining areas: Strother Creek, West Fork Black River, and Bee Fork. Greatest toxicity occurred in sediments from a 6-km reach of upper Strother Creek, but significant toxic effects occurred in sediments collected at least 14 km downstream of mining in all three watersheds. Toxic effects were significantly correlated with metal concentrations (nickel, zinc, cadmium, and lead) in sediments and pore waters and were generally consistent with predictions of metal toxicity risks based on sediment quality guidelines, although ammonia and manganese may also have contributed to toxicity at a few sites. Responses of amphipods in sediment toxicity tests were significantly correlated with characteristics of benthic invertebrate communities in study streams. These results indicate that toxicity of metals associated with sediments contributes to adverse ecological effects in streams draining the Viburnum Trend mining district.

  1. Manganese toxicity to tropical freshwater species in low hardness water.

    Science.gov (United States)

    Harford, Andrew J; Mooney, Thomas J; Trenfield, Melanie A; van Dam, Rick A

    2015-12-01

    Elevated manganese (Mn) is a common contaminant issue for mine water discharges, and previous studies have reported that its toxicity is ameliorated by H(+), Ca(2+), and Mg(2+) ions. In the present study, the toxicity of Mn was assessed in a high risk scenario, that is, the slightly acidic, soft waters of Magela Creek, Kakadu National Park, Northern Territory, Australia. Toxicity estimates were derived for 6 tropical freshwater species (Chlorella sp., Lemna aequinoctialis, Amerianna cumingi, Moinodaphnia macleayi, Hydra viridissima, and Mogurnda mogurnda). Low effect chronic inhibition concentration (IC10) and acute lethal concentration (LC05) values ranged between 140 μg L(-1) and 80,000 μg L(-1), with 3 of the species tested (M. macleayi, A. cumingi, and H. viridissima) being more sensitive to Mn than all but 1 species in the international literature (Hyalella azteca). A loss of Mn was observed on the final day for 2 of the H. viridissima toxicity tests, which may be a result of the complex speciation of Mn and biological oxidation. International data from toxicity tests conducted in natural water with a similar physicochemistry to Magela Creek water were combined with the present study's data to increase the sample size to produce a more reliable species sensitivity distribution. A 99% protection guideline value of 73 μg L(-1) (33-466 μg L(-1)) was derived; the low value of this guideline value reflects the higher toxicity of Mn in slightly acidic soft waters.

  2. Depletion of florfenicol amine in tilapia (Oreochromis sp.) maintained in a recirculating aquaculture system following Aquaflor(R)-medicated feed therapy (20 mg/kg BW/d for 10 days)

    Science.gov (United States)

    Gaikowski, Mark P.; Whitsel, Melissa K.; Charles, Shawn; Schleis, Susan M.; Crouch, Louis S.; Endris, Richard G.

    2013-01-01

    Aquaflor® [50% w w−1 florfenicol (FFC)], is approved for use in freshwater-reared warmwater finfish which include tilapia Oreochromis spp. in the United States to control mortality from Streptococcus iniae. The depletion of florfenicol amine (FFA), the marker residue of FFC, was evaluated after feeding FFC-medicated feed to deliver a nominal 20 mg FFC kg−1 BW d−1 dose (1.33× the label use of 15 mg FFC kg−1 BW d−1) to Nile tilapia O. niloticus and hybrid tilapia O. niloticus × O. aureus held in a recirculating aquaculture system (RAS) at production-scale holding densities. Florfenicol amine concentrations were determined in fillets taken from 10 fish before dosing and from 20 fish at nine time points after dosing (from 1 to 240 h post-dosing). Water samples were assayed for FFC before, during and after the dosing period. Parameters monitored included daily feed consumption and biofilter function (levels of ammonia, nitrite and nitrate). Mean fillet FFA concentration decreased from 13.77 μg g−1 at 1-h post dosing to 0.39 μg g−1 at 240-h post dosing. Water FFC concentration decreased from a maximum of 1400 ng mL−1 at 1 day post-dosing to 847 ng mL−1 at 240 h post-dosing. There were no adverse effects noted on fish, feed consumption or biofilter function associated with FFC-medicated feed administration to tilapia.

  3. Effects of sediment-spiked lufenuron on benthic macroinvertebrates in outdoor microcosms and single-species toxicity tests

    Energy Technology Data Exchange (ETDEWEB)

    Brock, T.C.M., E-mail: theo.brock@wur.nl [Alterra, Wageningen University and Research Centre, P.O. Box 47, 6700 AA Wageningen (Netherlands); Bas, D.A. [Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam (Netherlands); Belgers, J.D.M. [Alterra, Wageningen University and Research Centre, P.O. Box 47, 6700 AA Wageningen (Netherlands); Bibbe, L. [Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam (Netherlands); Boerwinkel, M-C.; Crum, S.J.H. [Alterra, Wageningen University and Research Centre, P.O. Box 47, 6700 AA Wageningen (Netherlands); Diepens, N.J. [Department of Aquatic Ecology and Water Quality Management, Wageningen University, P.O. Box 47, 6700 AA Wageningen (Netherlands); Kraak, M.H.S.; Vonk, J.A. [Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam (Netherlands); Roessink, I. [Alterra, Wageningen University and Research Centre, P.O. Box 47, 6700 AA Wageningen (Netherlands)

    2016-08-15

    Highlights: • In outdoor microcosms constructed with lufenuron-spiked sediment we observed that this insecticide persistent in the sediment compartment. • Sediment exposure to lufenuron caused population-level declines (insects and crustaceans) and increases (mainly oligochaete worms) of benthic invertebrates. • The direct and indirect effects observed in the microcosms were supported by results of sediment-spiked single species tests with Chironomus riparius, Hyalella azteca and Lumbriculus variegatus. • The tier-1 effect assessment procedure for sediment organisms recommended by the European Food Safety Authority is protective for the treatment-related responses observed in the microcosm test. - Abstract: Sediment ecotoxicity studies were conducted with lufenuron to (i) complement the results of a water-spiked mesocosm experiment with this lipophilic benzoylurea insecticide, (ii) to explore the predictive value of laboratory single-species tests for population and community-level responses of benthic macroinvertebrates, and (iii) to calibrate the tier-1 effect assessment procedure for sediment organisms. For this purpose the concentration-response relationships for macroinvertebrates between sediment-spiked microcosms and those of 28-d sediment-spiked single-species toxicity tests with Chironomus riparius, Hyalella azteca and Lumbriculus variegatus were compared. Lufenuron persisted in the sediment of the microcosms. On average, 87.7% of the initial lufenuron concentration could still be detected in the sediment after 12 weeks. Overall, benthic insects and crustaceans showed treatment-related declines and oligochaetes treatment-related increases. The lowest population-level NOEC in the microcosms was 0.79 μg lufenuron/g organic carbon in dry sediment (μg a.s./g OC) for Tanytarsini, Chironomini and Dero sp. Multivariate analysis of the responses of benthic macroinvertebrates revealed a community-level NOEC of 0.79 μg a.s./g OC. The treatment

  4. Los artistas españoles del éxodo y el llanto bajo el techo azteca

    Directory of Open Access Journals (Sweden)

    Cabañas Bravo, Miguel

    2009-02-01

    Full Text Available This article explains the characteristics that surrounded and singled out the Spanish artist exiled in Mexico after the Civil War, especially those referred to the number, the professional actitivy, the installation and integration, the association, the professional means and the influences. Therefore, the analysis is channelled into illustrating the whole of the path and collective action, standing out the links of this Spanish 20th century art branch with the social, political and cultural factors.El presente artículo trata de las características que rodearon y singularizaron al artista español exiliado en México tras la guerra civil, especialmente las referidas a número, actividad profesional, instalación e integración, agrupaciones, medios profesionales e influencias. Por tanto, el análisis se dirige a ilustrar el conjunto de su trayectoria y acción colectiva, resaltando las vinculaciones de esta extensión del arte español del siglo XX con los aspectos y condicionantes socio-políticos y culturales de inscripción.

  5. La educación higiénica y médica en los aztecas

    Directory of Open Access Journals (Sweden)

    Saúl GARCÍA BLANCO

    2009-11-01

    Full Text Available El deporte moderno, siendo un fenómeno genuino de nuestra época, hunde sus raíces en las manifestaciones culturales de las sociedades más antiguas. Las actividades físicas practicadas por los jóvenes de las distintas civilizaciones habidas, dieron lugar a lo que Ortega definió como «el origen deportivo del Estado». Sin embargo la actividad física, el juego y los deportes han sido considerados generalmente, y hasta tiempos recientes, como unas actividades triviales, casi carentes de valor. No obstante, si se desea comprender las distintas culturas habidas en el mundo, resulta indispensable el estudio de este tipo de actividades excepcionales del comportamiento humano.

  6. Los artistas españoles del éxodo y el llanto bajo el techo azteca

    OpenAIRE

    Cabañas Bravo, Miguel

    2009-01-01

    This article explains the characteristics that surrounded and singled out the Spanish artist exiled in Mexico after the Civil War, especially those referred to the number, the professional actitivy, the installation and integration, the association, the professional means and the influences. Therefore, the analysis is channelled into illustrating the whole of the path and collective action, standing out the links of this Spanish 20th century art branch with the social, political and cultural ...

  7. La educación higiénica y médica en los aztecas

    OpenAIRE

    García Blanco, Saúl

    2009-01-01

    El deporte moderno, siendo un fenómeno genuino de nuestra época, hunde sus raíces en las manifestaciones culturales de las sociedades más antiguas. Las actividades físicas practicadas por los jóvenes de las distintas civilizaciones habidas, dieron lugar a lo que Ortega definió como «el origen deportivo del Estado». Sin embargo la actividad física, el juego y los deportes han sido considerados generalmente, y hasta tiempos recientes, como unas actividades triviales, casi carentes de valor. No ...

  8. El Imperio azteca y su genio en la ingeniería en Mesoamérica (1325-1521)

    OpenAIRE

    Saidi, Mehdi

    2016-01-01

    En el siglo XV, los españoles descubrieron América, la llamaron el Nuevo Mundo, pero aunque esas tierras habían sido hasta entonces desconocidas para Europa, no eran nuevas, y tenían una larga y prestigiosa historia. Los pueblos indígenas que vivían en esas tierras no habían tenido contacto con el mundo exterior, pero aprendieron a construir y levantaron pueblos y ciudades. Se organizaron en sociedades, inventaron formas de gobierno, desarrollaron conceptos sobre el universo y ...

  9. Evaluation of the toxicity of sediments from the Anniston PCB Site to the mussel Lampsilis siliquoidea

    Science.gov (United States)

    Schein, Allison; Sinclair, Jesse A.; MacDonald, Donald D.; Ingersoll, Christopher G.; Kemble, Nile E.; Kunz, James L.

    2015-01-01

    concentrations of PCBs were associated with the highest concentrations of PAHs, PCDDs/PCDFs, and organochlorine pesticides. Specifically, sediments 08, 18, and 19 exceeded probable effect concentration quotients (PEC-Qs) of 1.0 for all organic classes of contaminants. These three sediment samples also had high concentrations of mercury and lead, which were the only metals found at elevated concentrations (i.e., above the probable effect concentration [PEC]) in the samples collected. Many sediment samples were highly contaminated with mercury, based on comparisons to samples collected from reference locations. The whole-sediment laboratory toxicity tests conducted with L. siliquoidea met the test acceptability criteria (e.g., control survival was greater than or equal to 80%). Survival of mussels was high in most samples, with 4 of 23 samples (17%) classified as toxic based on the survival endpoint. Biomass and weight were more sensitive endpoints for the L. siliquoidea toxicity tests, with both endpoints classifying 52% of the samples as toxic. Samples 19 and 30 were most toxic to L. siliquoidea, as they were classified as toxic according to all four endpoints (survival, biomass, weight, and length). Mussels were less sensitive in toxicity tests conducted with sediments from the Anniston PCB Site than Hyalella azteca and Chironomus dilutus. Biomass of L. siliquoidea was less sensitive compared to biomass of H. azteca or biomass of larval C. dilutus. Based on the most sensitive endpoint for each species, 52% of the samples were toxic to L. siliquoidea, whereas 67% of sediments were toxic to H. azteca (based on reproduction) and 65% were toxic to C. dilutus (based on adult biomass). The low-risk toxicity threshold (TTLR) was higher for L. siliquoidea biomass (e.g., 20,400 µg/kg dry weight [DW]) compared to that for H. azteca reproduction (e.g., 499 µg/kg DW) or C. dilutus adult biomass (e.g., 1,140 µg/kg DW; MacDonald et al. 2014). While mussels such as L. sili

  10. An assessment of the toxicity of phthalate esters to freshwater benthos. 2. Sediment exposures.

    Science.gov (United States)

    Call, D J; Cox, D A; Geiger, D L; Genisot, K I; Markee, T P; Brooke, L T; Polkinghorne, C N; VandeVenter, F A; Gorsuch, J W; Robillard, K A; Parkerton, T F; Reiley, M C; Ankley, G T; Mount, D R

    2001-08-01

    Seven phthalate esters were evaluated for their 10-d toxicity to the freshwater invertebrates Hyalella azteca and Chironomus tentans in sediment. The esters were diethyl phthalate (DEP), di-n-butyl phthalate (DBP), di-n-hexyl phthalate (DHP), di-(2-ethylhexyl) phthalate (DEHP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), and a commercial mixture of C7, C9, and C11 isophthalate esters (711P). All seven esters were tested in a sediment containing 4.80% total organic carbon (TOC), and DBP alone was tested in two additional sediments with 2.45 and 14.1% TOC. Sediment spiking concentrations for DEP and DBP were based on LC50 (lethal concentration for 50% of the population) values from water-only toxicity tests, sediment organic carbon concentration, and equilibrium partitioning (EqP) theory. The five higher molecular weight phthalate esters (DHP, DEHP, DINP, DIDP, 711P), two of which were tested and found to be nontoxic in water-only tests (i.e., DHP and DEHP), were tested at single concentrations between 2,100 and 3,200 mg/kg dry weight. Preliminary spiking studies were performed to assess phthalate ester stability under test conditions. The five higher molecular weight phthalate esters in sediment had no effect on survival or growth of either C. tentans or H. azteca, consistent with predictions based on water-only tests and EqP theory. The 10-d LC50 values for DBP and H. azteca were >17,400, >29,500, and >71,900 mg/kg dry weight for the low, medium, and high TOC sediments, respectively. These values are more than 30x greater than predicted by EqP theory and may reflect the fact that H. azteca is an epibenthic species and not an obligative burrower. The 10-d LC50 values for DBP and C. tentans were 826, 1,664, and 4.730 mg/kg dry weight for the low, medium, and high TOC sediments, respectively. These values are within a factor of two of the values predicted by EqP theory. Pore-water 10-d LC50 values for DBP (dissolved fraction) and C. tentans in the three

  11. Effects of contaminants in dredge material from the Lower Savannah River

    Science.gov (United States)

    Winger, P.V.; Lasier, P.J.; White, D.H.; Seginak, J.T.

    2000-01-01

    Contaminants entering aquatic systems from agricultural, industrial, and municipal activities are generally sequestered in bottom sediments. The environmental significance of contaminants associated with sediments dredged from Savannah Harbor, Georgia, USA, are unknown. To evaluate potential effects of contaminants in river sediments and sediments dredged and stored in upland disposal areas on fish and wildlife species, solid-phase sediment and sediment pore water from Front River, Back River, an unnamed Tidal Creek on Back River, and Middle River of the distributary system of the lower Savannah River were tested for toxicity using the freshwater amphipod Hyalella azteca. In addition, bioaccumulation of metals from sediments collected from two dredge-disposal areas was determined using the freshwater oligochaete Lumbriculus variegatus. Livers from green-winged teals (Anas crecca) and lesser yellowlegs (Tringa flavipes) foraging in the dredge-spoil areas and raccoons (Procyon lotor) from the dredge-disposal/river area and an upland site were collected for metal analyses. Survival of H. azteca was not reduced in solid-phase sediment exposures, but was reduced in pore water from several locations receiving drainage from dredge-disposal areas. Basic water chemistry (ammonia, alkalinity, salinity) was responsible for the reduced survival at several sites, but PAHs, metals, and other unidentified factors were responsible at other sites. Metal residues in sediments from the Tidal Creek and Middle River reflected drainage or seepage from adjacent dredge-disposal areas, which could potentially reduce habitat quality in these areas. Trace metals increased in L. variegatus exposed in the laboratory to dredge-disposal sediments; As, Cu, Hg, Se, and Zn bioaccumulated to concentrations higher than those in the sediments. Certain metals (Cd, Hg, Mo, Se) were higher in livers of birds and raccoons than those in dredge-spoil sediments suggesting bioavailability. Cadmium, Ct, Hg, Pb

  12. Comparison of macroinvertebrate-derived stream quality metrics between snag and riffle habitats

    Science.gov (United States)

    Stepenuck, K.F.; Crunkilton, R.L.; Bozek, Michael A.; Wang, L.

    2008-01-01

    We compared benthic macroinvertebrate assemblage structure at snag and riffle habitats in 43 Wisconsin streams across a range of watershed urbanization using a variety of stream quality metrics. Discriminant analysis indicated that dominant taxa at riffles and snags differed; Hydropsychid caddisflies (Hydropsyche betteni and Cheumatopsyche spp.) and elmid beetles (Optioservus spp. and Stenemlis spp.) typified riffles, whereas isopods (Asellus intermedius) and amphipods (Hyalella azteca and Gammarus pseudolimnaeus) predominated in snags. Analysis of covariance indicated that samples from snag and riffle habitats differed significantly in their response to the urbanization gradient for the Hilsenhoff biotic index (BI), Shannon's diversity index, and percent of filterers, shredders, and pollution intolerant Ephemeroptera, Plecoptera, and Trichoptera (EPT) at each stream site (p ??? 0.10). These differences suggest that although macroinvertebrate assemblages present in either habitat type are sensitive to detecting the effects of urbanization, metrics derived from different habitats should not be intermixed when assessing stream quality through biomonitoring. This can be a limitation to resource managers who wish to compare water quality among streams where the same habitat type is not available at all stream locations, or where a specific habitat type (i.e., a riffle) is required to determine a metric value (i.e., BI). To account for differences in stream quality at sites lacking riffle habitat, snag-derived metric values can be adjusted based on those obtained from riffles that have been exposed to the same level of urbanization. Comparison of nonlinear regression equations that related stream quality metric values from the two habitat types to percent watershed urbanization indicated that snag habitats had on average 30.2 fewer percent EPT individuals, a lower diversity index value than riffles, and a BI value of 0.29 greater than riffles. ?? 2008 American Water

  13. Toxicity of metal-contaminated sediments from Keswick Reservoir, California, USA

    Energy Technology Data Exchange (ETDEWEB)

    Finlayson, B.; Fujimura, R.; Huang, Z.Z.

    2000-02-01

    Keswick Reservoir, California, USA, receives metal-laden acid-mine drainage (AMD) from the abandoned Iron Mountain Mine. Mixing of the AMD with reservoir water causes precipitation and deposition of metal-rich sludge in the reservoir. Hydroelectric generation activities can scour the sediments and mobilize trace metals cadmium, copper, and zinc into the water column, thus creating potentially toxic conditions to fish and aquatic invertebrates. Sediment samples collected from Keswick Reservoir in 1993 and 1994 were analyzed for acid-volatile sulfides and for simultaneously extractable metals (SEM), and whole sediments and sediment elutriates were tested for toxicity to rainbow trout (Oncorhynchus mykiss), amphipods (Hyalella azteca), and cladocerans (Ceriodaphnia dubia). Acid-volatile sulfide concentrations in the sediments were low (<10 {micro}mol/g H{sub 2}S), indicating that dissolved metals in the sediment pore water were not limited by sulfide. The SEM concentrations were generally high (up to 11 {micro}g/g Cd, 4,800 {micro}g/g Cu, and 1,600 {micro}g/g Zn, dry weight) in the sediments. Whole sediments and 20% w/w sediment elutriates from 16 sites were tested for toxicity. Low survival (as low as 0{degree}) in whole sediments was generally associated with copper and zinc, and to a lesser extent cadmium, concentrations that exceeded probable effect level values for freshwater sediments; survival also may have been influenced by low pH and alkalinity conditions. Low survival (as low as 0%) in sediment elutriates was also generally associated with higher concentrations of dissolved zinc. Further study is required to formulate sediment cleanup levels that are protective of fish and wildlife. Source control in the Iron Mountain Mine drainage will eventually significantly lessen the production of sediments.

  14. Assessing the potential toxicity of resuspended sediment

    Energy Technology Data Exchange (ETDEWEB)

    Bonnet, C.; Babut, M.; Ferard, J.F.; Martel, L.; Garric, J.

    2000-05-01

    Two moderately contaminated freshwater sediments (Sorel Harbour, St. Lawrence River, Canada) were subjected to a suspension event. The objective was to assess the environmental impact of the disposal of dredged material in water, in particular, the short-term effects of dumping on the water column and the long-term effects of dredged sediment deposits. In a series of microcosms, the sediments were left to stand for 25 d under flow-through conditions. In a second series of microcosms, sediments were vigorously suspended for 15 min before being left to settle and were submitted to the same treatment as reference sediments during the following 25 d. Physicochemical and biological parameters (Daphnia magna and Hydra attenuata survival) were measured in overlying water throughout the experiment. Sediment toxicity was assessed with Chironomus tentans and Hyalella azteca exposed to sediments collected at both the beginning and end of the 25-d period. Pore-water toxicity was evaluated with D. magna. During the suspension process, in the Sorel Harbour mixed sediment overlying water, the authors observed effects on H. attenuata survival and ammonia and metals (chromium, copper, and zinc) releases. Meanwhile, in reference (nonmixed) and mixed sediments as well as in associated pore waters, there were no significant chemical modifications no biological effects after the 25-d experiments. The developed approach, which attempts to simulate a dumping process, aims at allowing the assessment of the short- and long-term hazards resulting from a resuspension process in overlying water and in resettled sediments using both chemical and biological measurements.

  15. Evaluation of the impact of farming activity in the water quality in surface catchment areas in hydrographic basin from Mogi-Guacu and Pardo Rivers, Sao Paulo; Avaliacao do impacto da atividade agropecuaria na qualidade da agua em areas de captacao superficial nas bacias hidrograficas dos Rios Mogi-Guacu e Pardo, Sao Paulo

    Energy Technology Data Exchange (ETDEWEB)

    Katsuoka, Lidia

    2001-07-01

    This study was performed in 10 small basins located in the Mogi-Guacu and Pardo Rivers, in the Northeastern area of Sao Paulo State. The land belonging of these basins is used to grow row crops of potato, coffee and pasture areas. This study aimed to characterize small basins, to evaluate water and sediment quality and to correlate basic aspects of climatology, hydrology, toxicology and land uses to the physical, chemical and toxicological characteristics of the water in the streams. Geographic Information System (GIS) was used as a tool of evaluation of land uses and risk assessment was performed for a final evaluation. The samplings were carried out from June/1999 to June/2000 in the 13 collecting points. It was verified that water quality is dependent upon the rainy and dry periods and the harvest periods. In the beginning of rainy periods were found large concentrations of metals and traces of herbicides leachate from soil and, in the dry period the same event was verified, caused by concentration of the water. In August, September and October phosphorus concentrations were very low getting an improvement in the water quality. Al, Fe and Mn are majority elements of chemical compositions of rocks of the study area, and exceed the Brazilian Guidelines. The stream waters were classified as 44% oligotrophic, 42% mesotrophic and 14% eutrophic. Jaguari-Mirim River presented the largest values of Trophic Index (TI). Sediment analyses showed a great variety of organic compounds coming from anthropogenic activities (industrial and farming activity). Toxicity tests with hyalella azteca in the sediments presented toxicity for sediments from Sao Joao da Boa Vista and Divinolandia. A methodology was developed for organochlorinated pesticides by gas chromatography coupled to mass spectrometry (GCMS). The presence of organochlorinated pesticides was not verified. (author)

  16. Characterization of selected bed-sediment-bound organic and inorganic contaminants and toxicity, Barnegat Bay and major tributaries, New Jersey, 2012

    Science.gov (United States)

    Romanok, Kristin M.; Reilly, Timothy J.; Lopez, Anthony R.; Trainor, John J.; Hladik, Michelle L.; Stanley, Jacob K.; Farrar, Daniel

    2014-01-01

    A study of bed-sediment toxicity and organic and inorganic contaminants was conducted by the U.S. Geological Survey (USGS) in cooperation with the New Jersey Department of Environmental Protection (NJDEP). Bed-sediment samples were collected once from 22 sites in Barnegat Bay and selected major tributaries during August–September 2012 and analyzed for toxicity and a suite of organic and inorganic contaminants by the USGS and the U.S. Army Corps of Engineers. Sampling sites were selected to coincide with an existing water-quality monitoring network used by the NJDEP and others in order to evaluate water-quality conditions in Barnegat Bay and the surrounding watershed. Two of the 22 sites are reference sites and are within or adjacent to the study area; bed-sediment samples from reference sites allow for comparisons of results for the Barnegat Bay watershed to results from less affected settings within the region. Toxicity testing was conducted by exposing the estuarine amphipod Leptocheirus plumulosus and the freshwater amphipod Hyalella azteca to sediments for 28 days, and the percent survival, difference in biomass, and individual dry weights were measured. Reproductive effects also were evaluated for estuarine samples. Bed-sediment samples from four sites within Barnegat Bay were subjected to a toxicity identification evaluation to determine probable causes of toxicity. Samples were analyzed for a suite of 94 currently-used pesticides, 21 legacy pesticides, 24 trace elements, 40 polycyclic aromatic hydrocarbons, 7 polychlorinated biphenyls (PCBs) as Arochlor mixtures, and 145 individual PCB congeners. Concentrations of detected compounds were compared to sediment-quality guidelines, where appropriate.

  17. Factors influencing the partitioning and toxicity of nanotubes in the aquatic environment.

    Science.gov (United States)

    Kennedy, Alan J; Hull, Matthew S; Steevens, Jeffery A; Dontsova, Katerina M; Chappell, Mark A; Gunter, Jonas C; Weiss, Charles A

    2008-09-01

    Carbon nanotubes (NTs) may be among the most useful engineered nanomaterials for structural applications but could be difficult to study in ecotoxicological evaluations using existing tools relative to nanomaterials with a lower aspect ratio. Whereas the hydrophobicity and van der Waals interactions of NTs may suggest aggregation and sedimentation in aquatic systems, consideration regarding how engineered surface modifications influence their environmental fate and toxicology is needed. Surface modifications (e.g., functional groups and coatings) are intended to create conditions to make NTs dispersible in aqueous suspension, as required for some applications. In the present study, column stability and settling experiments indicated that raw, multiwalled NTs (MWNTs) settled more rapidly than carbon black and activated carbon particles, suggesting sediment as the ultimate repository. The presence of functional groups, however, slowed the settling of MWNTs (increasing order of stability: hydroxyl > carboxyl > raw), especially in combination with natural organic matter (NOM). Stabilized MWNTs in high concentrations of NOM provided relevance for water transport and toxicity studies. Aqueous exposures to raw MWNTs decreased Ceriodaphnia dubia viability, but such effects were not observed during exposure to functionalized MWNTs (> 80 mg/L). Sediment exposures of the amphipods Leptocheirus plumulosus and Hyalella azteca to different sizes of sediment-borne carbon particles at high concentration indicated mortality increased as particle size decreased, although raw MWNTs induced lower mortality (median lethal concentration [LC50], 50 to >264 g/kg) than carbon black (LC50, 18-40 g/kg) and activated carbon (LC50, 12-29 g/kg). Our findings stress that it may be inappropriate to classify all NTs into one category in terms of their environmental regulation.

  18. Toxicity and Geochemistry of Missouri Cave Stream Sediments

    Science.gov (United States)

    Lawler, C. A.; Besser, J.; Wicks, C. M.

    2005-05-01

    Water and sediment quality are among the most important variables affecting the survival of stygobites. In Tumbling Creek Cave, Taney County Missouri the population of the endangered cave snail, Antrobia culveri, has declined significantly over the past decade. The cause of the population decline is unknown but could be related to the quality of streambed sediment in which the cave snail lives. The objective of this study was to determine the toxicity and concentrations of heavy metals in the sediment of Tumbling Creek Cave and five other caves in Missouri. These sediments were analyzed to assess possible point sources from within the recharge areas of the caves and to provide baseline geochemical data to which Tumbling Creek Cave sediments could be compared. Standard sediment toxicity tests and ICP-MS analysis for heavy metals were conducted. Survival and reproduction of the amphipod, Hyalella azteca, did not differ significantly between cave sediments and a control sediment. However the growth of amphipods differed significantly among sites and was significantly reduced in sediments from Tumbling Creek Cave relative to controls. Concentrations of several metals in sediments differed substantially among locations, with elevated levels of zinc and copper occurring in Tumbling Creek Cave. However, none of the measured metal concentrations exceeded sediment quality guidelines derived to predict probable effects on benthic organisms and correlations between sediment metal concentrations and toxicity endpoints were generally weak. While elevated metal levels may play a part in the cave snail's decline, other factors may be of equal or greater importance. Ongoing analyses of persistent organic contaminants and total organic carbon in cave sediments, along with continued water quality monitoring, may provide data that will allow us to better understand this complicated problem.

  19. Fraunhofer Institut fuer Molekularbiologie und Angewandte Oekologie (IME). Annual report 2012/2013; Fraunhofer Institut fuer Molekularbiologie und Angewandte Oekologie (IME). Jahresbericht 2012/2013

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-03-15

    The Annual report 2012/2013 of the Fraunhofer Institute for molecular biology and applied ecology includes the following contributions: (A) Molecular Biology: A technology platform for human monoclonal antibodies against malaria antigens. Reducing the cold sweetening of potatoes during cold storage. BY2 cell - free lysate: an alternative eucaryotic in vitro translation system. Automated animal cell culture. Improvement of resource-use efficiency and productivity in crop plants. Optimizing transient protein expression in tobacco using predictive models. Microbial master-cell banks for biopharmaceutical production. Development and implementation of a plant-produced vaccine against yellow fever. Insect antennae as in situ biosensors. Communal and individual immunity - their relationship in Tribolium castaneum. A Drosophila model for aging. Analysis of insect transcriptomes, Biofuels: Hexanol production with Clostridia. Application of Targeted Proteomics for Metabolic Engineering of Clostridia. The Fraunhofer Future Foundation Malaria Project. Characterization and validation of predictive human experimental pain models. FCR Center for Systems Biotechnology business areas progress report. (B) Applied Ecology: Transformation/dissolution testing of silver nanoparticles. Effect of silver nanoparticles in the context of sewage sludge used in agriculture. Feasibility of biotic ligand models for routine monitoring. Estimating reasonable application dates related to BBCH crop development stages. Bioconcentration studies with the freshwater amphipod Hyalella azteca. Fish life cycle tests: Static vs. flow-through exposure. Vulnerable fish species for risk assessment of pesticides in Europe. Ecotoxicological testing of armor stones in mesocosms. The effect of wild yeast in traditional wines. Lifestock metabolism studies at Fraunhofer IME. Column generated concentrations of highly-lipophilic test substances.

  20. Identification of the first neuropeptides from the Amphipoda (Arthropoda, Crustacea).

    Science.gov (United States)

    Christie, Andrew E

    2014-09-15

    Despite being used as models in the field of ecotoxicology, including use in studies of endocrine disruption, little is known about the hormonal systems of amphipods, particularly their peptidergic signaling systems. Here, transcriptome shotgun assembly (TSA) sequences were used to predict the structures of the first neuropeptides from members of this crustacean order. Using a well-established workflow, BLAST searches of the extant amphipod TSA data were conducted for putative peptide-encoding transcripts. The pre/preprohormones deduced from the identified TSA sequences were then used to predict the mature structures of amphipod neuropeptides. In total, 43 putative peptide-encoding transcripts were identified from three amphipods, Echinogammarus veneris, Hyalella azteca and Melita plumulosa. Collectively, 139 distinct mature peptides (110 from E. veneris alone) were predicted from these TSA sequences. The identified peptides included members of the adipokinetic hormone/red pigment concentrating hormone, allatostatin A, allatostatin B, allatostatin C, bursicon α, bursicon β, crustacean hyperglycemic hormone, diuretic hormone 31, FLRFamide, molt-inhibiting hormone, myosuppressin, neuroparsin, neuropeptide F, orcokinin, pigment dispersing hormone (PDH), proctolin, RYamide, SIFamide, sulfakinin and tachykinin-related peptide families. Of particular note were the identifications of orcokinins possessing SFDEIDR- rather than the typical NFDEIDR- amino-termini, e.g. SFDEINRSNFGFN, a carboxyl-terminally amidated orcokinin, i.e. SFDEINRSNFGFSamide, PDHs longer than the stereotypical 18 amino acids, e.g. NSELLNTLLGSKSLAALRAAamide, and a 13 rather than 12 amino acid long SIFamide, i.e. GPYRKPPFNGSIFamide. These data not only provide the first descriptions of native amphipod neuropeptides, but also represent a new resource for initiating investigations of peptidergic signaling in the Amphipoda.

  1. Neonicotinoids in the Canadian aquatic environment: a literature review on current use products with a focus on fate, exposure, and biological effects.

    Science.gov (United States)

    Anderson, J C; Dubetz, C; Palace, V P

    2015-02-01

    Developed to replace organophosphate and carbamate insecticides, neonicotinoids are structurally similar to nicotine. The three main neonicotinoid insecticides, imidacloprid, clothianidin, and thiamethoxam, are being re-evaluated by Health Canada's Pest Management Regulatory Agency (PMRA). An important aspect of the re-evaluation is the potential for effects in non-target organisms, including aquatic organisms. Leaching into surface waters is one of the major concerns surrounding extensive use of neonicotinoids, especially in close proximity to water bodies. The PMRA has classified IMI as 'persistent' with a 'high' leaching potential. Globally, neonicotinoids have been detected in a variety of water bodies, typically at concentrations in the low μg/L range. While IMI has been included in some monitoring exercises, there are currently very few published data for the presence of CLO and THM in Canadian water bodies. The majority of neonicotinoid toxicity studies have been conducted with IMI due to its longer presence on the market and high prevalence of use. Aquatic insects are particularly vulnerable to neonicotinoids and chronic toxicity has been observed at concentrations of IMI below 1 μg/L. Acute toxicity has been reported at concentrations below 20 μg/L for the most sensitive species, including Hyalella azteca, ostracods, and Chironomus riparius. Fish, algae, amphibians, and molluscs are relatively insensitive to IMI. However, the biological effects of THM and CLO have not been as well explored. The Canadian interim water quality guideline for IMI is 0.23 μg/L, but there is currently insufficient use, fate, and toxicological information available to establish guidelines for CLO and THM. Based on concentrations of neonicotinoids reported in surface waters in Canada and globally, there is potential for aquatic invertebrates to be negatively impacted by neonicotinoids. Therefore, it is necessary to address knowledge gaps to inform decisions around guidelines

  2. Development and application of freshwater sediment-toxicity benchmarks for currently used pesticides.

    Science.gov (United States)

    Nowell, Lisa H; Norman, Julia E; Ingersoll, Christopher G; Moran, Patrick W

    2016-04-15

    Sediment-toxicity benchmarks are needed to interpret the biological significance of currently used pesticides detected in whole sediments. Two types of freshwater sediment benchmarks for pesticides were developed using spiked-sediment bioassay (SSB) data from the literature. These benchmarks can be used to interpret sediment-toxicity data or to assess the potential toxicity of pesticides in whole sediment. The Likely Effect Benchmark (LEB) defines a pesticide concentration in whole sediment above which there is a high probability of adverse effects on benthic invertebrates, and the Threshold Effect Benchmark (TEB) defines a concentration below which adverse effects are unlikely. For compounds without available SSBs, benchmarks were estimated using equilibrium partitioning (EqP). When a sediment sample contains a pesticide mixture, benchmark quotients can be summed for all detected pesticides to produce an indicator of potential toxicity for that mixture. Benchmarks were developed for 48 pesticide compounds using SSB data and 81 compounds using the EqP approach. In an example application, data for pesticides measured in sediment from 197 streams across the United States were evaluated using these benchmarks, and compared to measured toxicity from whole-sediment toxicity tests conducted with the amphipod Hyalella azteca (28-d exposures) and the midge Chironomus dilutus (10-d exposures). Amphipod survival, weight, and biomass were significantly and inversely related to summed benchmark quotients, whereas midge survival, weight, and biomass showed no relationship to benchmarks. Samples with LEB exceedances were rare (n=3), but all were toxic to amphipods (i.e., significantly different from control). Significant toxicity to amphipods was observed for 72% of samples exceeding one or more TEBs, compared to 18% of samples below all TEBs. Factors affecting toxicity below TEBs may include the presence of contaminants other than pesticides, physical/chemical characteristics

  3. Toxicity of Cúspide 480SL® spray mixture formulation of glyphosate to aquatic organisms.

    Science.gov (United States)

    Currie, Zachary; Prosser, Ryan S; Rodriguez-Gil, Jose Luis; Mahon, Kim; Poirier, Dave; Solomon, Keith R

    2015-05-01

    In 2011, an alternative formulation of glyphosate (Cúspide 480SL®) was chosen to replace Roundup-SL®, Fuete-SL®, and Gly-41® for the control of Erythroxylum coca, the source of cocaine, in Colombia. Cúspide 480SL contains the active ingredient glyphosate isopropylamine (IPA) salt, which is the same active ingredient used in previous formulations. However, Cúspide 480SL contains an alkyl polyglycoside surfactant rather than the polyethoxylated tallow amine (POEA) surfactant used in other formulations and known to be more toxic to nonprimary producing aquatic organisms than glyphosate itself. An adjuvant, Cosmo-Flux F411, and water also are added to the spray mixture before application. Aquatic ecosystems adjacent to the target coca fields might be exposed to the spray mix, placing aquatic organisms at risk. Because no toxicity data were available for spray mixture on aquatic organisms, acute toxicity tests were conducted on aquatic plants, invertebrates, and fish, by using the Cúspide 480SL spray mix as described on the label. Based on the median effective concentration (EC50) values for similar organisms, the spray mixture was less toxic to aquatic organisms than formulations previously used for the control of coca (i.e., Roundup-SL, Fuete-SL, and Gly-41). A physical effect induced by Cosmo-Flux F411 was observed in Daphnia magna, Ceriodaphnia dubia, and Hyalella azteca, causing the invertebrates to be trapped in an oily film that was present at the surface of the water. However, a hazard assessment for the Cúspide 480SL spray mix, using estimated worst-case exposure scenario concentrations and EC50 values from the toxicity tests, indicated de minimis hazard for the tested aquatic animals, with hazard quotients all <1.

  4. Treated wastewater effluent as a source of pyrethroids and fipronil at Todos Santos Bay, Mexico: Its impact on sediments and organisms.

    Science.gov (United States)

    Hernández-Guzmán, Félix Augusto; Macías-Zamora, José Vinicio; Ramírez-Álvarez, Nancy; Alvarez-Aguilar, Arturo; Quezada-Hernández, Cristina; Fonseca, Ana Paula

    2017-06-03

    Pyrethroids are insecticides widely used to control pests and disease vectors in residential areas and agricultural lands. Pyrethroids are emerging pollutants, and their use is a growing concern because of their toxicity potential to aquatic organisms. Todos Santos Bay and the Punta Banda estuary, 2 coastal bodies located to the south of the Southern California Bight, were studied to establish a baseline of the current conditions of pollution by pyrethroids and fipronil. Eight pyrethroids, along with fipronil and its 2 metabolites, were determined in effluents from wastewater-treatment plants (n = 3), surface sediments (n = 32), and 3 locations with mussels (Mytilus californianus, n = 9). Bifenthrin, permethrin, and cypermethrin were the most common pyrethroids found in the study areas and were widespread in sediments, mussels, and wastewater-treated effluents. Fipronil and its metabolites were detected in mussels and wastewater-treated effluents only. Total pyrethroid concentrations in sediments ranged from 0.04 to 1.95 ng/g dry weight in the Punta Banda estuary (n = 13) and from 0.07 to 6.62 ng/g dry weight in Todos Santos Bay (n = 19). Moreover, total pyrethroids in mussels ranged from 1.19 to 6.15 ng/g wet weight. Based on the toxic unit data calculated for pyrethroids and fipronil for Eohaustorius estuarius and Hyalella azteca, little to no impact is expected to the benthic population structure. Environ Toxicol Chem 2017;9999:1-8. © 2017 SETAC. © 2017 SETAC.

  5. Impact of environmentally based chemical hardness on uranium speciation and toxicity in six aquatic species.

    Science.gov (United States)

    Goulet, Richard R; Thompson, Patsy A; Serben, Kerrie C; Eickhoff, Curtis V

    2015-03-01

    Treated effluent discharge from uranium (U) mines and mills elevates the concentrations of U, calcium (Ca), magnesium (Mg), and sulfate (SO4 (2-) ) above natural levels in receiving waters. Many investigations on the effect of hardness on U toxicity have been experiments on the combined effects of changes in hardness, pH, and alkalinity, which do not represent water chemistry downstream of U mines and mills. Therefore, more toxicity studies with water chemistry encountered downstream of U mines and mills are necessary to support predictive assessments of impacts of U discharge to the environment. Acute and chronic U toxicity laboratory bioassays were realized with 6 freshwater species in waters of low alkalinity, circumneutral pH, and a range of chemical hardness as found in field samples collected downstream of U mines and mills. In laboratory-tested waters, speciation calculations suggested that free uranyl ion concentrations remained constant despite increasing chemical hardness. When hardness increased while pH remained circumneutral and alkalinity low, U toxicity decreased only to Hyalella azteca and Pseudokirchneriella subcapitata. Also, Ca and Mg did not compete with U for the same uptake sites. The present study confirms that the majority of studies concluding that hardness affected U toxicity were in fact studies in which alkalinity and pH were the stronger influence. The results thus confirm that studies predicting impacts of U downstream of mines and mills should not consider chemical hardness. Environ Toxicol Chem 2015;34:562-574. © 2014 The Authors. Published by Wiley Periodicals, Inc. on behalf of SETAC.

  6. Toxicological evaluation of sediment samples from Burns Harbor, Porter County, Indiana

    Energy Technology Data Exchange (ETDEWEB)

    Ward, J.A.; Pinza, M.R.; Barrows, M.E.; Karls, R.K.; Word, J.Q. [Battelle/Marine Sciences Lab., Sequim, WA (United States)

    1994-05-01

    The US Army Corps of Engineers (USACE) Chicago District is authorized to maintain the water depths in Burns Harbor at navigable levels. In order to maintain these levels, sediments must be dredged and disposed of at approved disposal sites. To make a 404 (b) 1 open-water disposal evaluation, the dredged sediment may be evaluated through a series of toxicological tests to assess its potential for causing an adverse environmental effect. Battelle/Marine Sciences Laboratory (MSL) was contracted by USACE to perform these freshwater toxicity tests. The tests were designed to simulate conditions that organisms living within an aquatic dredged material disposal site might experience during disposal operations, and included both bedded-sediment (solid-phase) and suspended-sediment (elutriate) tests. Test samples were collected by USACE personnel and composited into three test treatments representing potential dredging areas (Management Units {number_sign}1, {number_sign}2, and {number_sign}3). Four toxicological tests were conducted in support of this program. The solid-phase tests included the amphipod, Hyalella azteca, and the midge, Chironomus tentans. The elutriate tests included the fathead minnow, Pimephales promelas, and the daphnid, Daphnia magna. Testing was conducted following standard procedures provided by USACE which are consistent with ASTM protocols and the Evaluation of Dredged Material Proposed for Discharge in Inland and Near Coastal Waters -- Testing Manual (Draft) Inland Testing Manual (EPA/USACE 1993), known as the ``Draft Inland Testing Manual.`` The suitability of sediment representing the management units for open-water disposal was evaluated following the guidelines contained in the Draft Inland Testing Manual.

  7. Biological and chemical characterization of metal bioavailability in sediments from Lake Roosevelt, Columbia River, Washington, USA

    Science.gov (United States)

    Besser, J.M.; Brumbaugh, W.G.; Ivey, C.D.; Ingersoll, C.G.; Moran, P.W.

    2008-01-01

    We studied the bioavailability and toxicity of copper, zinc, arsenic, cadmium, and lead in sediments from Lake Roosevelt (LR), a reservoir on the Columbia River in Washington, USA that receives inputs of metals from an upstream smelter facility. We characterized chronic sediment toxicity, metal bioaccumulation, and metal concentrations in sediment and pore water from eight study sites: one site upstream in the Columbia River, six sites in the reservoir, and a reference site in an uncontaminated tributary. Total recoverable metal concentrations in LR sediments generally decreased from upstream to downstream in the study area, but sediments from two sites in the reservoir had metal concentrations much lower than adjacent reservoir sites and similar to the reference site, apparently due to erosion of uncontaminated bank soils. Concentrations of acid-volatile sulfide in LR sediments were too low to provide strong controls on metal bioavailability, and selective sediment extractions indicated that metals in most LR sediments were primarily associated with iron and manganese oxides. Oligochaetes (Lumbriculus variegatus) accumulated greatest concentrations of copper from the river sediment, and greatest concentrations of arsenic, cadmium, and lead from reservoir sediments. Chronic toxic effects on amphipods (Hyalella azteca; reduced survival) and midge larvae (Chironomus dilutus; reduced growth) in whole-sediment exposures were generally consistent with predictions of metal toxicity based on empirical and equilibrium partitioning-based sediment quality guidelines. Elevated metal concentrations in pore waters of some LR sediments suggested that metals released from iron and manganese oxides under anoxic conditions contributed to metal bioaccumulation and toxicity. Results of both chemical and biological assays indicate that metals in sediments from both riverine and reservoir habitats of Lake Roosevelt are available to benthic invertebrates. These findings will be used as

  8. Toxicity of silicon carbide nanowires to sediment-dwelling invertebrates in water or sediment exposures

    Science.gov (United States)

    Mwangi, Joseph N.; Wang, Ning; Ritts, Andrew; Kunz, James L.; Ingersoll, Christopher G.; Li, Hao; Deng, Baolin

    2011-01-01

    Silicon carbide nanowires (SiCNW) are insoluble in water. When released into an aquatic environment, SiCNW would likely accumulate in sediment. The objective of this study was to assess the toxicity of SiCNW to four freshwater sediment-dwelling organisms: amphipods (Hyalella azteca), midges (Chironomus dilutus), oligochaetes (Lumbriculus variegatus), and mussels (Lampsilis siliquoidea). Amphipods were exposed to either sonicated or nonsonicated SiCNW in water (1.0 g/L) for 48 h. Midges, mussels, and oligochaetes were exposed only to sonicated SiCNW in water for 96 h. In addition, amphipods were exposed to sonicated SiCNW in whole sediment for 10 d (44% SiCNW on dry wt basis). Mean 48-h survival of amphipods exposed to nonsonicated SiCNW in water was not significantly different from the control, whereas mean survival of amphipods exposed to sonicated SiCNW in two 48-h exposures (0 or 15% survival) was significantly different from the control (90 or 98% survival). In contrast, no effect of sonicated SiCNW was observed on survival of midges, mussels, or oligochaetes. Survival of amphipods was not significantly reduced in 10-d exposures to sonicated SiCNW either mixed in the sediment or layered on the sediment surface. However, significant reduction in amphipod biomass was observed with the SiCNW either mixed in sediment or layered on the sediment surface, and the reduction was more pronounced for SiCNW layered on the sediment. These results indicated that, under the experimental conditions, nonsonicated SiCNW in water were not acutely toxic to amphipods, sonicated SiCNW in water were acutely toxic to the amphipods, but not to other organisms tested, and sonicated SiCNW in sediment affected the growth but not the survival of amphipods.

  9. Fraunhofer Institut fuer Molekularbiologie und Angewandte Oekologie (IME). Annual report 2014/2015; Fraunhofer Institut fuer Molekularbiologie und Angewandte Oekologie (IME). Jahresbericht 2014/2015

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2015-07-01

    The Annual report 2014/2015 of the Fraunhofer Institute for molecular biology and applied ecology includes the following contributions: (A) Molecular Biology: TheraSECOURE - Novel immunotherapeutics for targeted cancer therapy; ''MultiNaBel ''- Automated diagnosis of leukemia; Breeding potato for optimized specialty starches; NGS-based zygosity detection in transgenic maize; High-throughput screen ing system for cellulases based on microfluidic devices; Filter aids reduce production costs for plant-derived biopharmaceuticals; Transient expression of recombinant proteins in packed plant cells; ERA-NET Biodiversa EXOTIC project on the invasive harlequin ladybird; AIM-Biotech supported by the Fraunhofer-Max Planck Cooperation program; Metabolic control analysis of the MEP pathway; Metabolic engineering of Clostridium spp. by genomic integration; The Fraunhofer Future Foundation malaria project; Autoantibodies to type 11 collagen as biomarkers of rheumatoid arthritis; Development of a new drug for the treatment of sepsis; Databionic drug research; Structure-based drug design; Neu{sup 2}: competence consortium for multiple sclerosis drug development; Natural compounds from marine fungi for the treatment of cancer; FCR Center for Systems Biotechnology (CSB): Two selected projects; Development and implementation of a plant-derived vaccine against yellow fever. (B) Applied Ecology: Comparison and improvement of laboratory water/sediment test systems; Inter-laboratory comparison of Hyalella Azteca exposure tests lasting 10-42 days; Substance- and matrix-related environmental monitoring of biocides; GERDA-geobased runoff, erosion and drainage risk assessment; The minimum detectable difference and reliability of mesocosm studies; Mechanistic effect models for the ecological risk assessment of pesticides; Molecular biology test for the online analysis of spontaneously-fermented wines; Coupling two test systems to determine the effect of wastewater

  10. Development and application of freshwater sediment-toxicity benchmarks for currently used pesticides

    Science.gov (United States)

    Nowell, Lisa H.; Norman, Julia E.; Ingersoll, Christopher G.; Moran, Patrick W.

    2016-01-01

    Sediment-toxicity benchmarks are needed to interpret the biological significance of currently used pesticides detected in whole sediments. Two types of freshwater sediment benchmarks for pesticides were developed using spiked-sediment bioassay (SSB) data from the literature. These benchmarks can be used to interpret sediment-toxicity data or to assess the potential toxicity of pesticides in whole sediment. The Likely Effect Benchmark (LEB) defines a pesticide concentration in whole sediment above which there is a high probability of adverse effects on benthic invertebrates, and the Threshold Effect Benchmark (TEB) defines a concentration below which adverse effects are unlikely. For compounds without available SSBs, benchmarks were estimated using equilibrium partitioning (EqP). When a sediment sample contains a pesticide mixture, benchmark quotients can be summed for all detected pesticides to produce an indicator of potential toxicity for that mixture. Benchmarks were developed for 48 pesticide compounds using SSB data and 81 compounds using the EqP approach. In an example application, data for pesticides measured in sediment from 197 streams across the United States were evaluated using these benchmarks, and compared to measured toxicity from whole-sediment toxicity tests conducted with the amphipod Hyalella azteca (28-d exposures) and the midge Chironomus dilutus (10-d exposures). Amphipod survival, weight, and biomass were significantly and inversely related to summed benchmark quotients, whereas midge survival, weight, and biomass showed no relationship to benchmarks. Samples with LEB exceedances were rare (n = 3), but all were toxic to amphipods (i.e., significantly different from control). Significant toxicity to amphipods was observed for 72% of samples exceeding one or more TEBs, compared to 18% of samples below all TEBs. Factors affecting toxicity below TEBs may include the presence of contaminants other than pesticides, physical

  11. Contamination and toxicity evaluation of pyrethroids in sediments of the Pearl River Estuary%珠江河口沉积物中拟除虫菊酯类农药污染及毒性评价

    Institute of Scientific and Technical Information of China (English)

    赵李娜; 赖子尼; 李秀丽; 王超; 帅方敏; 曾艳艺; 杨婉玲

    2013-01-01

    finally enter the aquatic environment and accumulate in the food chain and may cause serious ecological and health problems. The Pearl River Estuary is a unique ecological environment, yet little research has been conducted on pyrethroids in this area. This study aimed to determine if pyrethroids were detectable and widespread in the Pearl River Estuary and if concentrations were high enough to cause associated aquatic toxicity. Samples of surface sediments were collected in the Pearl River Estuary in May 2012 for analysis of pyrethroid residues using gas chromatograph-electron capture (GC-ECD), with Hyalella azteca used to evaluate the potential toxicity of sediment. Results showed that total mass fraction of the pyrethroids in the surface sediments ranged from ND to 6.59μg·kg-1, with an average of 0.75μg·kg-1, and exhibited a positive correlation with organic carbon. The highest content of pyrethroids was found at the Pearl River Bridge. The proportions of permethrin were highest in the Pearl River Estuary, accounting for 57.63% of total pyrethroids, with detections in 61.90%sediment samples, followed by fenvalerate, accounting for 16.39%of total pyrethroids, with detections in 28.57%sediment samples. Permethrin was the most abundant pyrethroid due to its wide-spread use in the Pearl River Delta and its degradation. The Pearl River Bridge site showed a pyrethroid sediment concentration of 6.59 μg·kg-1, which was probably due to it close proximity to Guangzhou, one of the most densely populated and economically developed cities in China. Toxic units (TUs) based on the LC50 of Hyalella azteca were calculated to estimate toxicity risk. The TUs in the Pearl River Estuary was in the range of 0-0.09, suggesting there were no obvious toxic effects of pyrethroids on Hyalella azteca, and no ecological risk of pyrethroids in the Pearl River Estuary. Results from this study will provide a basis for controlling organic pollution and managing the aquatic environment in local

  12. El peregrinar simbólico a través de la mitología azteca en Terra Nostra de Carlos Fuentes

    OpenAIRE

    Lergo, Inmaculada

    2011-01-01

    En Terra Nostra Carlos Fuentes exorciza la historia para ofrecerle una nueva oportunidad, para que las múltiples posibilidades de realización que quedaron latentes en su discurrir tengan su lugar, pues considera que sólo la ficción, la palabra escrita, puede viabilizar tiempos y espacios múltiples y simultáneos, y que sólo éstos pueden devolvernos la “memoria”, concepto clave que desentraña el complejo universo de la novela. Para ello, el mejor camino es el de lo mitológico, lo mágico, lo oní...

  13. Historia del arte e Imperio Azteca: la evidencia de las esculturas1/Art History and the Aztec Empire: the Evidence of Sculptures

    National Research Council Canada - National Science Library

    Emily Umberger

    2007-01-01

    .... In the following essay the possible contributions of art history are explored through the analysis of sculptures from Aztec colony areas in the nearby Toluca Valley and in more distant North Veracruz...

  14. Predigested Tank Model and Its Application in 10-days Averaged Inflow Forecast of the Longyangxia Reservoir during Raining Seasons%概化的Tank模型及其在龙羊峡水库汛期 旬平均入库流量预报中的应用

    Institute of Scientific and Technical Information of China (English)

    胡兴林

    2001-01-01

    The Longyangxia Reservoir is the biggest reservoir in the upper reaches of the Yellow River. It is located the eastern Tibetan Plateau. After the reservoir being completed a long-period drought occurs in the Tibetan Plateau. Less inflow comes into the reservoir. According to the flood control program, however, it is necessary to drain much water in the flood season for the reservoir security. In one aspect, managers must assure enough water after flood season to produce electricity. And in another aspect, they must assure the reservoir security. As the future rainfall and water income is unknown, the reservoir should not store much water in the flood control stage. Therefore a very high accuracy of long-and-middle inflow forecast is urgent. Tank model is a certainty mathematics model, which is used to forecast runoff in a basin. In this model only consider the input and output process, ignoring the physical process of basin water transformation. So for a very large basin with a complicated hydrologic and climate situation, this model can be well applied for flood control. The Tangnag Gauging Station is located in the upper reaches of the Yellow River, gauging the main inflow to the Longyangxia Reservoir. According to the underlying surface condition and runoff yield characteristics of the working basin, three independent runoff yield areas can be divided from the working basin. Each runoff yield area is predigested to be a single openinglinear water tank, of which the input is precipitation and the output is runoff. According to the water balance theory in flood period a model of calculating the runoff in flood period is worked out. Combining the three runoff yield areas, the runoff averaged over a flooperiod can be yielded. Thus, a medium-term runoff forecast model was put forward. Optimum seeking method is applied, and forecast parameter is determined by regression analysis. This model can be used to predict the mean inflow to the Longyangxia Reservoir for a period of ten days. Through fitting history data and testing the forecast it is found that the model is of a satisfying precision. The model calibration accuracy reaches to 95% or more. An actual forecast applied in July~September 1999 showed that in this model the maximum prediction error was 15. 2%, and the minimum one was 3.7%. The error is lower than the allowance, 20%, of the Standard 《 Hydrologic Information Forecast Code》.%Tank模型(又称为水箱模型),是一种用于流域径流预报的确定性水文模型.根据龙羊峡水库入库主要产流区——黄河上游唐乃亥水文站以上流域下垫面条件与产汇流特性,将其概化为以降雨量为输入、径流量为输出的单孔出流的线性水箱.并用于该水库汛期旬平均入库流量的预报.经对历史资料进行拟合和试验预报的结果表明,该模型具有较高的预报精度,现已应用于黄河上游龙羊峡水库汛期旬平均入库来水量的中期预报中,取得了十分显著的经济效益.

  15. Prospective, randomized trails of 10 days versus 30 days of antimicrobial treatment, including a short-term course of parenteral therapy, for childhood septic arthritis%儿童化脓性关节炎抗菌药物治疗疗程的前瞻性研究

    Institute of Scientific and Technical Information of China (English)

    秦晓华

    2010-01-01

    @@ 目前,儿童化脓性关节炎(septic arthritis, SA)的标准治疗方案为数星期的抗菌药物治疗(起始阶段静脉给药,后可改为口服),和关节切开术(特别是累及髋关节或肩关节时).但无充分证据证明该治疗方案的必要性,而抗菌药物治疗的疗程,目前尚无统一意见.这项芬兰的大型前瞻性随机对照研究为缩短SA抗菌药物治疗疗程,避免不必要的外科干预,从而简化治疗,为节约医疗成本提供有力依据.

  16. Changes of Thermoregulatory Responses and HSP70 in 10-day Heat Acclimation of Middle-Long-Distance Runners%中长跑运动员10天热适应过程中机体热调节反应及HSP70变化

    Institute of Scientific and Technical Information of China (English)

    吴卫兵; 王人卫; 许弟群

    2013-01-01

    目的:观察10天热适应过程中机体热调节反应及HSP70变化,探讨运动员运动训练和比赛实践中热适应的有效建立.方法:以8名中长跑男性运动员为受试对象,在温度为33℃、湿度为80%RH环境条件下,进行连续10天60 min、40%VO2 max强度的热适应运动,观察第2天、6天和10天机体热调节反应及HSP70变化.结果:中长跑运动员10天热适应过程中的体核温度、心率、主观感觉疲劳程度、出汗量、出汗率、汗液电解质离子和HSP70出现一些明显的变化,主要表现为热适应过程中运动后体核温度、心率逐渐下降,运动排汗能力增强,汗液电解质离子浓度显著下降(P<0.01),运动后HSP70水平显著升高(P<0.01).结论:热适应过程中机体出现体核温度下降、心率下降、排汗能力增强和HSP70水平升高等热适应性变化,提示中长跑运动员经过10天热适应运动后,机体已经有效地建立了热适应.

  17. Efecto de sedimentos naturales enriquecidos con zinc, en modelos aislados y en microcosmos, sobre tres especies de invertebrados bentónicos

    Directory of Open Access Journals (Sweden)

    Marcela Galar Martínez

    2006-06-01

    Full Text Available En los cuerpos acuáticos la disponibilidad de los tóxicos es limitada por las características fisicoquímicas de los sedimentos y agua, así como por las interacciones entre los diversos xenobióticos y entre las especies que los habitan. Por lo anterior, el objetivo del presente trabajo fue relacionar el efecto producido por el zinc (Zn sembrado en sedimentos del embalse Ignacio Ramírez (PIR, en modelos aislados y en microcosmos, sobre el ATP de tres organismos bentónicos con la biodisponibilidad del metal. Las especies seleccionadas fueron: Hyalella azteca, Limnodrilus hoffmeisteri y Stagnicola attenuata, dado que se encuentran en altas proporciones en el embalse y ocupan espacios diferentes en el bentos. Las muestras de sedimentos y organismos se colectaron en la estación de sequía (febrero de 1999. A los primeros se les determinó el pH, textura, tamaño de partícula, nitrógeno total, materia orgánica y concentración de metales (Zn, Fe, Cu y Ni. Posteriormente se realizó un estudio de toxicidad subletal utilizando dos tipos de sistemas estáticos (organismos aislados y en microcosmos. Ambos modelos contenían sedimentos de la PIR enriquecidos con Zn (concentración nominal de 0.8129 mg/kg y agua sintética en una proporción de 1:4. Los organismos de prueba fueron adicionados una vez alcanzado el equilibrio (2 hr considerando la cantidad de biomasa con respecto al volumen (1.0 g de organismo por cada 100 ml de agua:sedimento. Después de 0, 12, 24, 36, 48 y 72 hr de exposición se tomaron muestras del sedimento y de los hidrobiontes, a los cuales se les cuantificó el contenido de Zn por absorción atómica. A los organismos también se les determinó la concentración de ATP. Los resultados obtenidos muestran que el efecto producido por los sedimentos naturales enriquecidos se ve potenciado por la presencia de más de una especie en el sistema (microcosmos. Con respecto a los niveles de Zn, dos de los organismos (L. hoffmeisteri

  18. Acute sensitivity of the vernal pool fairy shrimp, Branchinecta lynchi (Anostraca; Branchinectidae), and surrogate species to 10 chemicals.

    Science.gov (United States)

    Ivey, Chris D; Besser, John M; Ingersoll, Chris G; Wang, Ning; Rogers, D Christopher; Raimondo, Sandy; Bauer, Candice R; Hammer, Edward J

    2017-03-01

    Vernal pool fairy shrimp, Branchinecta lynchi, (Branchiopoda; Anostraca) and other fairy shrimp species have been listed as threatened or endangered under the US Endangered Species Act. Because few data exist about the sensitivity of Branchinecta spp. to toxic effects of contaminants, it is difficult to determine whether they are adequately protected by water quality criteria. A series of acute (24-h) lethality/immobilization tests was conducted with 3 species of fairy shrimp (B. lynchi, Branchinecta lindahli, and Thamnocephalus platyurus) and 10 chemicals with varying modes of toxic action: ammonia, potassium, chloride, sulfate, chromium(VI), copper, nickel, zinc, alachlor, and metolachlor. The same chemicals were tested in 48-h tests with other branchiopods (the cladocerans Daphnia magna and Ceriodaphnia dubia) and an amphipod (Hyalella azteca), and in 96-h tests with snails (Physa gyrina and Lymnaea stagnalis). Median effect concentrations (EC50s) for B. lynchi were strongly correlated (r(2 ) = 0.975) with EC50s for the commercially available fairy shrimp species T. platyurus for most chemicals tested. Comparison of EC50s for fairy shrimp and EC50s for invertebrate taxa tested concurrently and with other published toxicity data indicated that fairy shrimp were relatively sensitive to potassium and several trace metals compared with other invertebrate taxa, although cladocerans, amphipods, and mussels had similar broad toxicant sensitivity. Interspecies correlation estimation models for predicting toxicity to fairy shrimp from surrogate species indicated that models with cladocerans and freshwater mussels as surrogates produced the best predictions of the sensitivity of fairy shrimp to contaminants. The results of these studies indicate that fairy shrimp are relatively sensitive to a range of toxicants, but Endangered Species Act-listed fairy shrimp of the genus Branchinecta were not consistently more sensitive than other fairy shrimp taxa. Environ Toxicol

  19. Acute sensitivity of the vernal pool fairy shrimp, Branchinecta lynchi (Anostraca; Branchinectidae), and surrogate species to 10 chemicals

    Science.gov (United States)

    Ivey, Chris D.; Besser, John M.; Ingersoll, Christopher G.; Wang, Ning; Rogers, Christopher; Raimondo, Sandy; Bauer, Candice R.; Hammer, Edward J.

    2017-01-01

    Vernal pool fairy shrimp, Branchinecta lynchi, (Branchiopoda; Anostraca) and other fairy shrimp species have been listed as threatened or endangered under the US Endangered Species Act. Because few data exist about the sensitivity of Branchinecta spp. to toxic effects of contaminants, it is difficult to determine whether they are adequately protected by water quality criteria. A series of acute (24-h) lethality/immobilization tests was conducted with 3 species of fairy shrimp (B. lynchi, Branchinecta lindahli, and Thamnocephalus platyurus) and 10 chemicals with varying modes of toxic action: ammonia, potassium, chloride, sulfate, chromium(VI), copper, nickel, zinc, alachlor, and metolachlor. The same chemicals were tested in 48-h tests with other branchiopods (the cladocerans Daphnia magna and Ceriodaphnia dubia) and an amphipod (Hyalella azteca), and in 96-h tests with snails (Physa gyrina and Lymnaea stagnalis). Median effect concentrations (EC50s) for B. lynchi were strongly correlated (r2 = 0.975) with EC50s for the commercially available fairy shrimp species T. platyurus for most chemicals tested. Comparison of EC50s for fairy shrimp and EC50s for invertebrate taxa tested concurrently and with other published toxicity data indicated that fairy shrimp were relatively sensitive to potassium and several trace metals compared with other invertebrate taxa, although cladocerans, amphipods, and mussels had similar broad toxicant sensitivity. Interspecies correlation estimation models for predicting toxicity to fairy shrimp from surrogate species indicated that models with cladocerans and freshwater mussels as surrogates produced the best predictions of the sensitivity of fairy shrimp to contaminants. The results of these studies indicate that fairy shrimp are relatively sensitive to a range of toxicants, but Endangered Species Act-listed fairy shrimp of the genus Branchinecta were not consistently more sensitive than other fairy shrimp taxa. Environ Toxicol Chem

  20. Development and application of freshwater sediment-toxicity benchmarks for currently used pesticides

    Energy Technology Data Exchange (ETDEWEB)

    Nowell, Lisa H., E-mail: lhnowell@usgs.gov [U.S. Geological Survey, California Water Science Center, Placer Hall, 6000 J Street, Sacramento, CA 95819 (United States); Norman, Julia E., E-mail: jnorman@usgs.gov [U.S. Geological Survey, Oregon Water Science Center, 2130 SW 5" t" h Avenue, Portland, OR 97201 (United States); Ingersoll, Christopher G., E-mail: cingersoll@usgs.gov [U.S. Geological Survey, Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO 65021 (United States); Moran, Patrick W., E-mail: pwmoran@usgs.gov [U.S. Geological Survey, Washington Water Science Center, 934 Broadway, Suite 300, Tacoma, WA 98402 (United States)

    2016-04-15

    Sediment-toxicity benchmarks are needed to interpret the biological significance of currently used pesticides detected in whole sediments. Two types of freshwater sediment benchmarks for pesticides were developed using spiked-sediment bioassay (SSB) data from the literature. These benchmarks can be used to interpret sediment-toxicity data or to assess the potential toxicity of pesticides in whole sediment. The Likely Effect Benchmark (LEB) defines a pesticide concentration in whole sediment above which there is a high probability of adverse effects on benthic invertebrates, and the Threshold Effect Benchmark (TEB) defines a concentration below which adverse effects are unlikely. For compounds without available SSBs, benchmarks were estimated using equilibrium partitioning (EqP). When a sediment sample contains a pesticide mixture, benchmark quotients can be summed for all detected pesticides to produce an indicator of potential toxicity for that mixture. Benchmarks were developed for 48 pesticide compounds using SSB data and 81 compounds using the EqP approach. In an example application, data for pesticides measured in sediment from 197 streams across the United States were evaluated using these benchmarks, and compared to measured toxicity from whole-sediment toxicity tests conducted with the amphipod Hyalella azteca (28-d exposures) and the midge Chironomus dilutus (10-d exposures). Amphipod survival, weight, and biomass were significantly and inversely related to summed benchmark quotients, whereas midge survival, weight, and biomass showed no relationship to benchmarks. Samples with LEB exceedances were rare (n = 3), but all were toxic to amphipods (i.e., significantly different from control). Significant toxicity to amphipods was observed for 72% of samples exceeding one or more TEBs, compared to 18% of samples below all TEBs. Factors affecting toxicity below TEBs may include the presence of contaminants other than pesticides, physical/chemical characteristics

  1. Sediment quality assessment using survival and embryo malformation tests in amphipod crustaceans: The Gulf of Riga, Baltic Sea AS case study

    Science.gov (United States)

    Strode, Evita; Jansons, Mintauts; Purina, Ingrida; Balode, Maija; Berezina, Nadezhda A.

    2017-08-01

    The aim of this study was to assess the toxicity of bottom sediment and to estimate the potential effects of contaminated sediment on health of benthic organisms in the Gulf of Riga (eastern Baltic Sea). Two endpoints were used: survival rate (acute toxicity test) of five crustacean amphipod species and frequency of embryo malformation (samples were collected from the field) in the two species. Toxic resistance of living animals to sediment quality was measured as survival rate (%) at 25 study sites from 2010-2012. Significant differences in the toxic resistance between species were found: 80-100% for Monoporeia affinis, 70-95% for Corophium volutator, 38-88% for Pontogammarus robustoides, 38-100% for Bathyporeia pilosa and 60-100% for Hyalella azteca. Reproductive disorders, measured as percentage (%) of malformed embryos per female, varied in the ranges of 0.0-9.5% in deep water species M. affinis and 0.3-7.5% in littoral species P. robustoides. Both the acute toxicity test and embryo malformation test (only M. affinis was used) indicated moderate and poor sediment quality at 20% and 12% accordingly in the study sites, low toxicity of sediment was estimated in 64% of cases, and no toxicity was recorded in the rest of the cases (4%). Additionally, sediment toxicity test using aquatic organisms was combined with sediment chemical analysis (trace metals) and the Benthic Quality Index (macrozoobenthos) was based on data collected from 13 sites in the Gulf of Riga in 2010 and used for triad sediment quality assessment. According to this combined approach, 23% of the bottom sediments were classified as likely impacted and 23% as possibly impacted (central and southern part of the Gulf). However, the remaining 54% was identified as likely un-impacted. The sediment quality assessment with single survival test or chemical analyses showed better sediment quality in the Gulf than the triad method. The embryo malformation test appeared to be more sensitive to pollution than

  2. Spatiotemporal patterns in community structure of macroinvertebrates inhabiting calcareous periphyton mats

    Science.gov (United States)

    Liston, S.E.; Trexler, J.C.

    2005-01-01

    Calcareous floating periphyton mats in the southern Everglades provide habitat for a diverse macroinvertebrate community that has not been well characterized. Our study described this community in an oligotrophic marsh, compared it with the macroinvertebrate community associated with adjacent epiphytic algae attached to macrophytes in the water column, and detected spatial patterns in density and community structure. The floating periphyton mat (floating mat) and epiphytic algae in the water column (submerged epiphyton) were sampled at 4 sites (???1 km apart) in northern Shark River Slough, Everglades National Park (ENP), in the early (July) and late (November) wet season. Two perpendicular 90-m transects were established at each site and ???100 samples were taken in a nested design. Sites were located in wet-prairie spikerush-dominated sloughs with similar water depths and emergent macrophyte communities. Floating mats were sampled by taking cores (6-cm diameter) that were sorted under magnification to enumerate infauna retained on a 250-??m-mesh sieve and with a maximum dimension >1 mm. Our results showed that floating mats provide habitat for a macroinvertebrate community with higher densities (no. animals/g ash-free dry mass) of Hyalella azteca, Dasyhelea spp., and Cladocera, and lower densities of Chironomidae and Planorbella spp. than communities associated with submerged epiphyton. Densities of the most common taxa increased 3x to 15x from early to late wet season, and community differences between the 2 habitat types became more pronounced. Floating-mat coverage and estimated floating-mat biomass increased 20 to 30%, and 30 to 110%, respectively, at most sites in the late wet season. Some intersite variation was observed in individual taxa, but no consistent spatial pattern in any taxon was detected at any scale (from 0.2 m to 3 km). Floating mats and their resident macroinvertebrate communities are important components in the Everglades food web. This

  3. Toxicity of sediments potentially contaminated by coal mining and natural gas extraction to unionid mussels and commonly tested benthic invertebrates.

    Science.gov (United States)

    Wang, Ning; Ingersoll, Christopher G; Kunz, James L; Brumbaugh, William G; Kane, Cindy M; Evans, R Brian; Alexander, Steven; Walker, Craig; Bakaletz, Steve

    2013-01-01

    Sediment toxicity tests were conducted to assess potential effects of contaminants associated with coal mining or natural gas extraction activities in the upper Tennessee River basin and eastern Cumberland River basin in the United States. Test species included two unionid mussels (rainbow mussel, Villosa iris, and wavy-rayed lampmussel, Lampsilis fasciola, 28-d exposures), and the commonly tested amphipod, Hyalella azteca (28-d exposure) and midge, Chironomus dilutus (10-d exposure). Sediments were collected from seven test sites with mussel communities classified as impacted and in proximity to coal mining or gas extraction activities, and from five reference sites with mussel communities classified as not impacted and no or limited coal mining or gas extraction activities. Additional samples were collected from six test sites potentially with high concentrations of polycyclic aromatic hydrocarbons (PAHs) and from a test site contaminated by a coal ash spill. Mean survival, length, or biomass of one or more test species was reduced in 10 of 14 test samples (71%) from impacted areas relative to the response of organisms in the five reference samples. A higher proportion of samples was classified as toxic to mussels (63% for rainbow mussels, 50% for wavy-rayed lampmussels) compared with amphipods (38%) or midge (38%). Concentrations of total recoverable metals and total PAHs in sediments did not exceed effects-based probable effect concentrations (PECs). However, the survival, length, or biomasses of the mussels were reduced significantly with increasing PEC quotients for metals and for total PAHs, or with increasing sum equilibrium-partitioning sediment benchmark toxic units for PAHs. The growth of the rainbow mussel also significantly decreased with increasing concentrations of a major anion (chloride) and major cations (calcium and magnesium) in sediment pore water. Results of the present study indicated that (1) the findings from laboratory tests were generally

  4. Toxicity of sediments potentially contaminated by coal mining and natural gas extraction to unionid mussels and commonly tested benthic invertebrates

    Science.gov (United States)

    Wang, Ning; Ingersoll, Christopher G.; Kunz, James L.; Brumbaugh, William G.; Kane, Cindy M.; Evans, R. Brian; Alexander, Steven; Walker, Craig; Bakaletz, Steve

    2013-01-01

    Sediment toxicity tests were conducted to assess potential effects of contaminants associated with coal mining or natural gas extraction activities in the upper Tennessee River basin and eastern Cumberland River basin in the United States. Test species included two unionid mussels (rainbow mussel, Villosa iris, and wavy-rayed lampmussel, Lampsilis fasciola, 28-d exposures), and the commonly tested amphipod, Hyalella azteca (28-d exposure) and midge, Chironomus dilutus (10-d exposure). Sediments were collected from seven test sites with mussel communities classified as impacted and in proximity to coal mining or gas extraction activities, and from five reference sites with mussel communities classified as not impacted and no or limited coal mining or gas extraction activities. Additional samples were collected from six test sites potentially with high concentrations of polycyclic aromatic hydrocarbons (PAHs) and from a test site contaminated by a coal ash spill. Mean survival, length, or biomass of one or more test species was reduced in 10 of 14 test samples (71%) from impacted areas relative to the response of organisms in the five reference samples. A higher proportion of samples was classified as toxic to mussels (63% for rainbow mussels, 50% for wavy-rayed lampmussels) compared with amphipods (38%) or midge (38%). Concentrations of total recoverable metals and total PAHs in sediments did not exceed effects-based probable effect concentrations (PECs). However, the survival, length, or biomasses of the mussels were reduced significantly with increasing PEC quotients for metals and for total PAHs, or with increasing sum equilibrium-partitioning sediment benchmark toxic units for PAHs. The growth of the rainbow mussel also significantly decreased with increasing concentrations of a major anion (chloride) and major cations (calcium and magnesium) in sediment pore water. Results of the present study indicated that (1) the findings from laboratory tests were generally

  5. Ecotoxicological assessment of sediments from Tiete river between Salesopolis and Suzano, SP (Brazil); Avaliacao ecotoxicologica de sedimentos do rio Tiete, entre os municipios de Salesopolis e Suzano, SP

    Energy Technology Data Exchange (ETDEWEB)

    Alegre, Gabriel Fonseca

    2009-07-01

    Once introduced into the aquatic environment, many substances can bind or be adsorbed by organic particles in suspension. Depending on the river morphology and hydrological conditions, these particles in suspension containing the contaminants can be deposited along its course, becoming part of the bottom sediments, making them actual sinks and often a source of contamination for the water column and benthic organisms. In the assessment of water, sediment has been one of the most important indicators of the contamination levels in aquatic ecosystems, representing the deposition of contaminants in the environment that occurred over the years and even decades. The Tiete River cross the Sao Paulo state, however, in the metropolitan region of Sao Paulo, the river shows the most severe degradation. In the region of Salesopolis, the waters of the Tiete River are used for public supply, but across the city of Mogi das Cruzes the water quality decreases significantly. Considering the importance of the Tiete river and the sediment for the aquatic biota, this study aimed to evaluate the toxicity of the sediment at five points along the Tiete river, between the cities of Salesopolis and Suzano, Sao Paulo. Four sampling were carried out: two in the summer (rainy season) and two in winter (dry season). The whole sediment was assessed by acute and chronic toxicity tests with Hyalella azteca and Ceriodaphnia dubia, respectively, the elutriate was assessed by chronic toxicity test using C. dubia, while the porewater was evaluated by acute toxicity test with Vibrio fischeri. Samples of river water were also evaluated for chronic toxicity tests with C. dubia. The quantification of metals and hydrocarbons in sediment samples was also carried out in order to correlate the biological effects with the chemical contamination. The obtained results with the whole sediment test indicate Mogi das Cruzes and Suzano cities as the most toxic sites and also as the sites with the highest

  6. Defeating the Narco-Insurgency within the United States

    Science.gov (United States)

    2010-05-01

    as the Mexican Federation Drug Cartel, the Gulf Drug Cartel, Mara Salvatrucha Thirteen (MS-13)4, and the Barrio Azteca transnational gang...U.S. crackdown on the Barrio Azteca transnational gang.7 U.S. law enforcement is predicting that transnational criminals in the Mexican narcotics...the Barrio Azteca gang--are now targeting U.S. law enforcement personnel for assassination in retaliation for a recent crackdown on members of the

  7. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... injection drug use and HIV. Television Networks: MunDos Azteca America Univision Telemundo Galavision Telefutura CW BET NBC ... Programs Latino Commission on AIDS Metro Teen Aids Azteca America Foundation/Vive Sin Drogras AdCouncil DC Department ...

  8. Operational Design Applied: Reframing Counterdrug Support to Law Enforcement in Texas

    Science.gov (United States)

    2012-06-08

    migrants, according to law enforcement reporting. For example, Bario Azteca –the Texas prison gang centered in El Paso–has worked with a Mexican TCO to...sales. Lastly, the Texas-based prison gang Barrio Azteca represents an example of a U.S. criminal gang that has been subsumed within a Mexican-based TCO

  9. U.S. Southwest Border Security: An Operational Approach

    Science.gov (United States)

    2012-06-08

    are well positioned to profit from illicit trafficking, according to law enforcement reporting. For example, Barrio Azteca – the Texas prison gang...prison gang Barrio Azteca represents an example of a U.S. criminal gang that has been subsumed within a Mexico-based TCO. This criminal gang now serves...

  10. Aquatic assessment of the Pike Hill Copper Mine Superfund site, Corinth, Vermont

    Science.gov (United States)

    Piatak, Nadine M.; Argue, Denise M.; Seal, Robert R.; Kiah, Richard G.; Besser, John M.; Coles, James F.; Hammarstrom, Jane M.; Levitan, Denise M.; Deacon, Jeffrey R.; Ingersoll, Christopher G.

    2013-01-01

    -based criteria are commonly lower values than the hardness-based criteria and thus suggest a greater degree or magnitude of impairment at the sampling locations. The riffle-habitat benthic invertebrate richness and abundance data correlate strongly with the extent of impact based on water quality for both brooks. Similarly, the fish community assessments document degraded conditions throughout most of Pike Hill Brook, whereas the data for the tributary to Cookville Brook suggest less degradation to this brook. The sediment environment shows similar extents of impairment to the surface-water environment, with most sampling locations in Pike Hill Brook, including the wetland areas, and the tributary to Cookville Brook affected. Sediment impairment is caused by elevated copper concentrations, although localized degradation due to elevated cadmium and zinc concentrations was documented on the basis of exceedances of probable effects concentrations (PECs). In contrast to impairment determined by exceedances of PECs, equilibrium-partitioning sediment benchmarks (based on simultaneously extracted metals, acid volatile sulfides, and total organic carbon) predict no toxic effects in sediments at the background locations and uncertain toxic effects throughout Pike Hill Brook and the tributary to Cookville Brook, with the exception of the most downstream Cookville Brook location, which indicated no toxic effects. Acute laboratory toxicity testing using the amphipod Hyalella azteca and the midge Chironomus dilutus on pore waters extracted from sediment in situ indicate impairment (based on tests with H. azteca) at only one location in Pike Hill Brook and no impairment in the tributary to Cookville Brook. Chronic laboratory sediment toxicity testing using H. azteca and C. dilutus indicated toxicity in Pike Hill Brook at several locations in the lower reach and two locations in the tributary to Cookville Brook. Toxicity was not indicated for either species in sediment from the most acidic

  11. A temporary social parasite of tropical plant-ants improves the fitness of a myrmecophyte

    Science.gov (United States)

    Dejean, Alain; Leroy, Céline; Corbara, Bruno; Céréghino, Régis; Roux, Olivier; Hérault, Bruno; Rossi, Vivien; Guerrero, Roberto J.; Delabie, Jacques H. C.; Orivel, Jérôme; Boulay, Raphaël

    2010-10-01

    Myrmecophytes offer plant-ants a nesting place in exchange for protection from their enemies, particularly defoliators. These obligate ant-plant mutualisms are common model systems for studying factors that allow horizontally transmitted mutualisms to persist since parasites of ant-myrmecophyte mutualisms exploit the rewards provided by host plants whilst providing no protection in return. In pioneer formations in French Guiana, Azteca alfari and Azteca ovaticeps are known to be mutualists of myrmecophytic Cecropia ( Cecropia ants). Here, we show that Azteca andreae, whose colonies build carton nests on myrmecophytic Cecropia, is not a parasite of Azteca- Cecropia mutualisms nor is it a temporary social parasite of A. alfari; it is, however, a temporary social parasite of A. ovaticeps. Contrarily to the two mutualistic Azteca species that are only occasional predators feeding mostly on hemipteran honeydew and food bodies provided by the host trees, A. andreae workers, which also attend hemipterans, do not exploit the food bodies. Rather, they employ an effective hunting technique where the leaf margins are fringed with ambushing workers, waiting for insects to alight. As a result, the host trees’ fitness is not affected as A. andreae colonies protect their foliage better than do mutualistic Azteca species resulting in greater fruit production. Yet, contrarily to mutualistic Azteca, when host tree development does not keep pace with colony growth, A. andreae workers forage on surrounding plants; the colonies can even move to a non- Cecropia tree.

  12. Toxicopathological Effects of the Sunscreen UV Filter, Oxybenzone (Benzophenone-3), on Coral Planulae and Cultured Primary Cells and Its Environmental Contamination in Hawaii and the U.S. Virgin Islands.

    Science.gov (United States)

    Downs, C A; Kramarsky-Winter, Esti; Segal, Roee; Fauth, John; Knutson, Sean; Bronstein, Omri; Ciner, Frederic R; Jeger, Rina; Lichtenfeld, Yona; Woodley, Cheryl M; Pennington, Paul; Cadenas, Kelli; Kushmaro, Ariel; Loya, Yossi

    2016-02-01

    Toxicity persistence to the nontarget amphipod Hyalella curvispina in runoff events following chlorpyrifos applications to soy experimental plots was compared in conventional and no-till management. Two application scenarios were compared: an early-season application with the soil almost bare and a late-season application after the foliage had attained complete soil cover. H. curvispina was exposed to chlorpyrifos using two different test systems: a short-term (48 h) runoff water exposure and a long-term (10 days) soil exposure. Both commonly used crop management practices for soybean production resulted in runoff toxicity following pesticide applications and represent a toxicity risk for adjacent inland waters. Toxicity persistence was longer after the earlier than the late season application, likely because of higher volatilization and photodecomposition losses from the soy canopy than from the soil. For the early-season application, toxicity persisted longer in the no-till plots than in the conventional tillage plots. Suspended matter was higher in the conventional treatment. Chlorpyrifos sorption to suspended matter likely contributed to the shorter persistence. For the late-season application, toxicity persisted longer in the conventional treatment. The causes remain conjectural. The soil organic carbon content was higher in the no-till treatment. Sorption to organic matter might have contributed to the shorter chlorpyrifos toxicity persistence in no-till management. Late applications are more frequent and prevail longer throughout the soy growing season. Overall, the no-till management practice seems preferably because shorter toxicity persistence in runoff represents a lower environmental risk for the adjacent inland waters.

  13. Non-target trials with Pseudomonas fluorescens strain CL145A, a lethal control agent of dreissenid mussels (Bivalvia: Dreissenidae

    Directory of Open Access Journals (Sweden)

    Daniel P. Molloy

    2013-01-01

    Full Text Available In an effort to develop an efficacious and environmentally safe method for managing zebra mussels (Dreissena polymorpha and quaggamussels (Dreissena rostriformis bugensis, we initiated a research project investigating the potential use of bacteria and their naturalmetabolic products as biocontrol agents. This project resulted in the discovery of an environmental isolate lethal to dreissenid mussels,Pseudomonas fluorescens strain CL145A (Pf-CL145A. In previous published reports we have demonstrated that: 1 Pf-CL145A’s mode ofaction is intoxication (not infection; 2 natural product within ingested bacterial cells lyse digestive tract epithelial cells leading to dreisseniddeath; and 3 high dreissenid kill rates (>90% are achievable following treatment with Pf-CL145A cells, irrespective of whether thebacterial cells are dead or alive. Investigating the environmental safety of Pf-CL145A was also a key element in our research efforts, andherein, we report the results of non-target trials demonstrating Pf-CL145A’s high specificity to dreissenids. These acute toxicity trials weretypically single-dose, short-term (24-72 h exposures to Pf-CL145A cells under aerated conditions at concentrations highly lethal todreissenids (100 or 200 mg/L. These trials produced no evidence of mortality among the ciliate Colpidium colpoda, the cladoceran Daphniamagna, three fish species (Pimephales promelas, Salmo trutta, and Lepomis macrochirus, and seven bivalve species (Mytilus edulis,Pyganodon grandis, Pyganodon cataracta, Lasmigona compressa, Strophitus undulatus, Lampsilis radiata, and Elliptio complanata. Lowmortality (3-27% was recorded in the amphipod Hyalella azteca, but additional trials suggested that most, if not all, of the mortality couldbe attributed to some other unidentified factor (e.g., possibly particle load or a water quality issue rather than Pf-CL145A’s dreissenidkillingnatural product. In terms of potential environmental safety, the results of

  14. Characterization of the hydrology, water chemistry, and aquatic communities of selected springs in the St. Johns River Water Management District, Florida, 2004

    Science.gov (United States)

    Phelps, G.G.; Walsh, Stephen J.; Gerwig, Robert M.; Tate, William B.

    2006-01-01

    from the Silver Springs group and in both boils at Gemini Springs. No pesticides were detected in water samples from De Leon Spring and Green Spring. Evidence of denitrification was indicated by the presence of excess nitrogen gas in water samples from most of the springs. Aquatic communities varied among the springs. Large floating mats of cyanobacteria (blue-green algae), identified as Lyngbya wollei, were observed in De Leon Spring during all sampling events in 2004. At Gemini Springs, the dominant periphyton was Rhizoclonium sp. Of the three springs sampled for benthic invertebrates, De Leon Spring had the highest overall species richness and most disturbance intolerant species (Florida Index = 4). Green Spring had the lowest species richness of the springs sampled. Based on qualitative comparisons, overall macroinvertebrate species richness seemed to be negatively related to magnesium, potassium, sodium, and specific conductance. Invertebrate abundance was greatest when dissolved oxygen and nitrate were high but phosphorus and potassium concentrations were low. Dipteran abundance seemed to be positively associated with specific conductance and total organic carbon but negatively associated with nitrate-N. Amphipods were the numerically dominant group collected in most (six of nine) collections. Shifts in amphipod abundance of the two species collected (Gammarus sp. and Hyalella azteca) varied by season among the three springs, but there were no trends evident in the variation. Fish populations were relatively species-rich at the Silver Springs group, De Leon Spring, and Gemini Springs, but not at Green Spring. Nonindigenous fish species were observed at all springs except Green Spring.

  15. Evaluation of Metal Toxicity in Streams Affected by Abandoned Mine Lands, Upper Animas River Watershed, Colorado

    Science.gov (United States)

    Besser, John M.; Allert, Ann L.; Hardesty, Douglas K.; Ingersoll, Christopher G.; May, Thomas W.; Wang, Ning; Leib, Kenneth J.

    2001-01-01

    water; (3) to develop site-specific thresholds for toxicity of Zn and Cu in stream water; and (4) to develop models of the contributions of Cu and Zn to toxicity of stream water, which may be used to characterize toxicity before and after planned remediation efforts. We evaluated the toxicity of metal-contaminated sediments by conducting sediment toxicity tests with two species of benthic invertebrates, the midge, Chironomus tentans. and the amphipod, Hyalella azteca. Laboratory toxicity tests with both taxa, exposed to fine stream-bed sediments collected in September 1997, showed some evidence of sediment toxicity, as survival of midge larvae in sediments from Cement Creek (C48) and lower Mineral Creek (M34), and growth of amphipods in sediments from these sites and three Animas River sites (A68, Animas at Silverton; A72, Animas below Silverton, and A73, Animas at Elk Park) were significantly reduced compared to a reference site, South Mineral Creek (SMC) . Amphipods were also exposed to site water and fine stream-bed sediment, separately and in combination, during the late summer low flow period (August-September) of 1998. In these studies, stream water, with no sediment present, from all five sites tested (same sites as above, except C48) caused 90% to 100% mortality of amphipods. In contrast, significant reductions in survival of amphipods occurred at two sites (A72 and SMC) in exposures with field-collected sediment plus stream water, and at only one site (A72) in exposures with sediments and clean overlying water. Concentrations of Zn, Pb, Cu, and Cd were high in both sediment and pore water (interstitial water) from most sites tested, but greatest sediment toxicity was apparently associated with greater concentrations of Fe and/or Al in sediments. These results suggest that fine stream-bed sediments of the more contaminated stream reaches of the upper Animas River watershed are toxic to benthic invertebrates, but that these impacts are less serious than tox

  16. Modul.LES: a multi-compartment, multi-organism aquatic life support system as experimental platform for research in ∆g

    Science.gov (United States)

    Hilbig, Reinhard; Anken, Ralf; Grimm, Dennis

    nitrogene-cycle (concentration of ammonium, nitrite and nitrate) as well as conductivity will be measured. For this long term mission an external food supply as has been used with OmegaHab is not sufficient and, therefore, in OmegaHab-XP a nutrition compartment has been added. OmegaHab-XP is a multi-trophic system, designed as a basic concept and test-bed for future multi-modular platform Modul.LES. OmegaHab-XP comprises four different trophic lev-els. The algae experimental container is used as CO2 / O2 exchanger and serves as oxygen source for all heterotrophic organisms. The fish compartment is divided into two areas -namely a hatchery (larval cichlid fish Oreochromis mossambicus) and a fish tank (subadult cichlids). Once the yolk sack is resorbed (stage 19) the juvenile fish are capable to leave the hatchery via escapements into the fish compartment. In order to enable the development of fish from larval yolk sack stages to subadult fish a nutrition compartment is enclosed: In this nutrition compartment the crustacean Hyalella azteca will reproduce and build up a stable population by feeding on the Rigid Hornwort (Ceratophyllum demersum). Younger crustaceans can cross the barrier to the fish tank and can serve as nutrition for fully developed subadult fish. Waste products of all organisms will be assimilated by the water snail Biomphalaria glabrata. The scientific concept of Modul.LES is to establish a multidisciplinary framework of scientists and areas of scientific research (biophysics, molecular-organismic biology, biochemistry etc.) to analyze impacts of g on plants and animals.

  17. Toxicity of chromium (VI) to two mussels and an amphipod in water-only exposures with or without a co-stressor of elevated temperature, zinc, or nitrate

    Science.gov (United States)

    Wang, Ning; Kunz, James L.; Ivey, Chris D.; Ingersoll, Christopher G.; Barnhart, M. Christopher; Glidewell, Elizabeth A.

    2017-01-01

    The objectives of the present study were to develop methods for propagating western pearlshell (Margaritifera falcata) for laboratory toxicity testing and evaluate acute and chronic toxicity of chromium VI [Cr(VI)] to the pearlshell and a commonly tested mussel (fatmucket, Lampsilis siliquoidea at 20 °C or in association with a co-stressor of elevated temperature (27 °C), zinc (50 µg Zn/L), or nitrate (35 mg NO3/L). A commonly tested invertebrate (amphipod, Hyalella azteca) also was tested in chronic exposures. Newly transformed pearlshell (~1 week old) were successfully cultured and tested in acute 96 h Cr exposures (control survival 100%). However, the grow-out of juveniles in culture for chronic toxicity testing was less successful and chronic 28-day Cr toxicity tests started with 4 month-old pearlshell failed due to low control survival (39–68%). Acute median effect concentration (EC50) for the pearlshell (919 µg Cr/L) and fatmucket (456 µg Cr/L) tested at 20 °C without a co-stressor decreased by a factor of > 2 at elevated temperature but did not decrease at elevated Zn or elevated NO3. Chronic 28-day Cr tests were completed successfully with the fatmucket and amphipod (control survival 83–98%). Chronic maximum acceptable toxicant concentration (MATC) for fatmucket at 20 °C (26 µg Cr/L) decreased by a factor of 2 at elevated temperature or NO3 but did not decrease at elevated Zn. However, chronic MATC for amphipod at 20 °C (13 µg Cr/L) did not decrease at elevated temperature, Zn, or NO3. Acute EC50s for both mussels tested with or without a co-stressor were above the final acute value used to derive United States Environmental Protection Agency acute water quality criterion (WQC) for Cr(VI); however, chronic MATCs for fatmucket at elevated temperature or NO3 and chronic MATCs for the amphipod at 20 °C with or without elevated Zn or NO3 were about equal to the chronic WQC. The results indicate that (1) the elevated temperature

  18. Derivation and Application of Sediment Quality Criteria of Cd and Hg for the Xiangjiang River%湘江沉积物镉和汞质量基准的建立及其应用

    Institute of Scientific and Technical Information of China (English)

    蒋博峰; 桑磊鑫; 孙卫玲; 郝伟; 李丽; 邓宝山

    2013-01-01

    沉积物质量基准是保护底栖生物免受污染物危害的保护性临界水平,可用来评估与沉积物结合的污染物的影响,并为底栖生物保护和沉积物的科学管理提供依据.分析了湘江43个采样点沉积物、上覆水、间隙水和植物中Cd和Hg含量,选取钩虾做沉积物毒理实验,利用相平衡分配法、加标毒理实验法和背景值法确定湘江沉积物Cd和Hg质量基准低值(SQC-L)分别为1.89 mg·kg-1和0.13 mg·kg-1,基准高值(SQC-H)分别为28.32 mg·kg-1和0.79 mg· kg-1.经与国内外基准值比较,并与底栖生物监测数据和植物监测数据对比分析,表明确定的基准值合理-应用该基准值评价湘江沉积物质量现状发现,湘江沉积物Cd和Hg含量低于SQC-L和高于SQC-H的采样点所占比例较低,74.4%和76.7%的采样点沉积物Cd和Hg含量在SQC-L和SQC-H之间.%Sediment quality criterion (SQC) is the concentrations of sediment-associated contaminants that are unlikely to be associated with sediment toxicity or other adverse effects on benthic invertebrates. Thus, the derivation of SQC is crucial to protect benthic invertebrates, and can serve as the tool for scientific sediment management. Sediment, interstitial water, and plant samples were collected at 43 sampling sites from the Xiangjiang River, and metal concentrations were determined. Based on equilibrium partitioning approach, spiked sediment toxicity approach using Hyalella azteca, and background value approach, SQC for Cd and Hg in the Xiangjiang River was derived. Results showed that, SQC-L for Cd and Hg in the Xiangjiang River were 1. 89 mg·kg-1 and 0. 13 mg·kg-1 respectively, and SQC-H were 28.32 mg·kg-1 and 0.79 mg·kg-1 respectively. SQC were comparable to those in previous studies. Also, the reasonability of SQC was demonstrated by the heavy metal concentrations in plants, matching sediment chemistry and toxicity data for benthic invertebrates in the Xiangjiang River. To assess the

  19. Review of the Ecotoxicological Properties of the Methylenedianiline Substances.

    Science.gov (United States)

    Schupp, T; Allmendinger, H; Bossuyt, B T A; Hidding, B; Tury, B; West, R J

    Concerning chronic toxicity, D. magna is the most sensitive species tested against MDA aquatic exposures, with a 21 days-NOEC of 0.00525 mg/L. Exposure of daphnids takes place via the aquatic phase. Other species of the same phylum (Arthropoda) appear to be less sensitive albeit with exposures via soil or sediment, with a 28 days-NOEC of 562 mg/kg d. w. soil (F. candida) and 41.3 mg/kg d. w. sediment (Hyalella azteca), for reproductive and survival endpoints, respectively. Also for acute toxicity, D. magna is more sensitive than the other species, with an 48 h-EC50 that spreads over two orders of magnitude, ranging from 0.019 to 2.7 mg/L. Fish show a more uniform reaction to MDA, with 96 h-LC50 ranging from about 20 to 60 mg/L; chronic data for fish are not available. Acute toxicity data for algae and cyanobacteria are in the range of 1-10 mg/L; based on growth rate, the 72 h-NOECr or ErC10 of MDA to algae is 0.3-9.3 mg/L.For sediment organisms, the black worm L. variegatus shows the highest sensitivity against MDA with a NOEC between ≤3.75 mg/kg and 30 mg/kg d. w., followed by the amphipod H. azteca. The lower sensitivity of L. variegatus in the second study compared to the first study is obviously attributable to the different feeding regimes (semi-continuous feeding against pre-spiked sediment). One argument might be that semi-continuous feeding allows the organisms to avoid the contaminated food. However, a change from semi-continuous feeding to sediment pre-spiked with nettle powder (Urtica sp.) results in an earlier and much stronger increase in ammonia concentration in the system. This became apparent after both studies on the blackworm were finalized. The ammonia 96 h-EC50 for the blackworm is 0.69 mg/L at pH = 8.2, and the 96 h-EC10 at pH = 8.2 is 0.33 mg/L (Hickey and Vickers, Arch Environ Contam Toxicol 26:292-298, 1994). As a result, the lower NOEC and LOEC in the second study with L. variegatus are probably attributable to

  20. Actitudes homofóbicas entre los indígenas del Nuevo Mundo: los casos azteca, inca y mapuche en fuentes de los siglos XVI y XVII/Homophobic Attitudes Among Indigenous People in the New World: Aztecs, Incas and Mapuches Through 16th and 17th Century Sources

    National Research Council Canada - National Science Library

    Mauricio González Arenas; César Gamboa

    2015-01-01

    ... toward homosexual behavior. It argues, analyzing Aztec, Inca and Mapuche attitudes from sixteenth-century and seventeenth-century sources, that America was not at all the gay paradise that many have wanted to see and publicize...

  1. Revision of the new world genus Crassomicrodus Ashmead (Hymenoptera, Braconidae, Agathidinae, with an identification key to species

    Directory of Open Access Journals (Sweden)

    José Figueroa

    2011-10-01

    Full Text Available A key to species and descriptions are presented for 14 species of the New World genus Crassomicrodus Ashmead. Seven new species, C. azteca, C. clypealis, C. costaricensis, C. jalisciensis, C. mariae, C. oaxaquensis, and C. olgae are described. C. fenestratus (Viereck is synonymized with C. nigriceps (Cresson. C. melanopleurus (Ashmead is recognized as a valid species.

  2. Revision of the new world genus Crassomicrodus Ashmead (Hymenoptera, Braconidae, Agathidinae), with an identification key to species

    Science.gov (United States)

    Figueroa, José Isaac; Sharkey, Michael Joseph; Nápoles, Jesus Romero; García, José Antonio Sánchez; Martínez, Ana Mabel; López-Martínez, Victor; Pineda, Samuel

    2011-01-01

    Abstract A key to species and descriptions are presented for 14 species of the New World genus Crassomicrodus Ashmead. Seven new species, Crassomicrodus azteca, Crassomicrodus clypealis, Crassomicrodus costaricensis, Crassomicrodus jalisciensis, Crassomicrodus mariae, Crassomicrodus oaxaquensis,and Crassomicrodus olgae are described. Crassomicrodus fenestratus (Viereck) is synonymized with Crassomicrodus nigriceps (Cresson). Crassomicrodus melanopleurus (Ashmead) is recognized as a valid species. PMID:22144862

  3. Latin America Report No. 2721.

    Science.gov (United States)

    2007-11-02

    such products are taxed. 3k Tax Table for Individuals Compleaento <<*) Impuesto Q. de rente - (I) Kenta Imponible imponible Impuesto sobre...shipyards, in which 10 vessels of the Azteca type and tunny boats have already been built. hk According to the admiral, nine ships of the Aguila type

  4. Pest repellent properties of ant pheromones

    DEFF Research Database (Denmark)

    Offenberg, Joachim

    2012-01-01

    ant species (iii) Azteca instabilis and (iv) Camponotus textor reduce herbivory by flea beetles (Margaridisa sp.), whereas (v) deposits from Solenopsis geminata, did not lead to reduced herbivory. Further evidence for the impact of ant pheromones comes from studies showing that non-herbivorous ant...

  5. Genus Parichoronyssus (Acari: Macronyssidae) and a description of a new species from Mexico.

    Science.gov (United States)

    Morales-Malacara, J B

    1996-01-01

    The genus Parichoronyssus Radovsky (1966), is redefined, and Parichoronyssus lopezi Morales-Malacara is described as a new species from specimens collected from a bat, Dermanura azteca, taken in Tlaxcala, Mexico. A key to the 6 species of Parichoronyssus is provided.

  6. Análisis de elementos gráficos de contenido occidental en los glifos de los códices coloniales del centro de México: el caso de los antropónimos castellanos

    National Research Council Canada - National Science Library

    Juan José Batalla Rosado

    2015-01-01

    ... culturales occidentales. Palabras clave: Códices mesoamericanos, escritura jeroglífica náhuatl, cultura azteca. Analysis of Western Graphics Elements in the Glyphs of Colonial Central Mexican Codices: The Case of Spanish Anthroponyms ABSTRACT In this text, we present the study of Spanish anthroponyms containing «Western» elements. We analyze the «l...

  7. Population Regulation of Mansonia Mosquitoes on Water Lettuce (Pistia stratiotes L.).

    Science.gov (United States)

    1986-07-01

    azteca Naucoridae Decac~daPelocoris ap. Family unknown Belostomatidae Belostoma op. Insecta Lethocerus 3p. Diptera Culicidae Coleoptera Mansonia dyarl...Technical Information Center (FJTIC) ATTN: DT IC -DDAC a Cameron Station Alexandria, VA 22304-6145 1 copy Dea- School of Medicine Uniformed Services

  8. Assessing the cause of impacts on benthic organisms near Rouyn-Noranda, Quebec

    Energy Technology Data Exchange (ETDEWEB)

    Borgmann, U.; Nowierski, M.; Grapentine, L.C.; Dixon, D.G

    2004-05-01

    Sediments from lakes near Rouyn-Noranda, Quebec, contain elevated concentrations of several metals, including Cd, Cu, Pb and Zn. Amphipods, fingernail clams, mayflies and tanytarsid midges were absent, and sediment toxicity was observed in chronic tests with Hyalella in sediments from Lac Dufault, the lake closest to Rouyn-Noranda. Bioaccumulation by Hyalella demonstrated elevated bioavailability of Cd, Co, Cr, Pb and Tl, but only Cd was accumulated to levels close to the toxic threshold. Copper, which is regulated by Hyalella, was not elevated in these amphipods, but it was elevated in overlying water in the toxicity tests. Toxic effects in Lac Dufault sediments are probably caused primarily by Cd, at least in amphipods, with a possible minor contribution from Cu. An integrated assessment, including sediment chemistry, benthic community composition, sediment toxicity, metal bioaccumulation in benthos, and comparison of bioaccumulation and/or overlying water concentrations with threshold effect concentrations, provides the best indication of effects and their cause. - Metal bioaccumulation and metals in overlying water during toxicity tests help identify the cause of sediment toxicity and reduced benthic biodiversity.

  9. New records of spider wasps (Hymenoptera, Pompilidae from Colombia

    Directory of Open Access Journals (Sweden)

    Ana Castro Huertas

    2014-09-01

    Full Text Available New records of genera and species of spider wasps (Hymenoptera: Pompilidae from Colombia are provided. Agenioideus, Cryptocheilus, Evagetes, Mystacagenia, and Xerochares are newly recorded genera from Colombia. Nineteen species are first recorded from Colombia: Aimatocare vitrea (Fox; Ageniella azteca (Cameron; Ageniella curtipinus (Cameron; Ageniella fallax (Arlé; Ageniella hirsuta Banks; Ageniella pilifrons (Cameron; Ageniella pretiosa Banks; Ageniella sanguinolenta (Smith; Ageniella zeteki (Banks; Agenioideus birkmanni (Banks; Aporus (Aporus cuzco Evans; Aporus (Cosmiaporus diverticulus (Fox; Aporus (Notoplaniceps canescens Smith; Euplaniceps exilis (Banks; Euplaniceps herbertii (Fox; Irenangelus clarus Evans; Mystacagenia bellula Evans; Phanochilus nobilitatus (Smith and Xerochares expulsus Schulz. The following species and genera have their occurence ranges expanded for South America: Ageniella azteca (Cameron; Ageniella zeteki (Banks; Agenioideus birkmanni (Banks; and Xerochares expulsus Schulz; Cryptocheilus Panzer; and Xerochares Evans.

  10. Two myrmecophilous scale insects, Cryptostigma urichi (Cockerell (Hemiptera, Coccidae and Farinococcus multispinosus Morrison (Hemiptera, Pseudococcidae, cohabiting inside branches of Anadenanthera falcata (Benth. Speg. (Fabales, Fabaceae in the Cerrado area of São Paulo State, Brazil Duas cochonilhas mirmecófilas, Cryptostigma urichi (Cockerell (Hemiptera, Coccidae e Farinococcus multispinosus Morrison (Hemiptera, Pseudococcidae, coabitando no interior de ramos de Anadenanthera falcata (Benth. Speg. (Fabales, Fabaceae em área de Cerrado do Estado de São Paulo, Brasil

    Directory of Open Access Journals (Sweden)

    André R. Nascimento

    2012-12-01

    Full Text Available The soft scale Cryptostigma urichi (Cockerell, 1894 and the mealybug Farinococcus multispinosus Morrison, 1922 are reported cohabiting inside branches of Anadenanthera falcata (Benth. Speg. (Angico-preto, both tended by the ant Azteca oecocordia Longino, 2007 (Hymenoptera, Formicidae. This interaction was observed in the Cerrado region sensu stricto, at the Federal University of São Carlos, UFSCar, Brazil. A. oecocordia is recorded for the first time in Brazil.O coccídeo Cryptostigma urichi (Cockerell, 1894 e o pseudococcídeo Farinococcus multispinosus Morrison, 1922 são registrados coabitando no interior de galhos de Anadenanthera falcata (Benth. Speg. (Angico-preto, ambos atendidos pela formiga Azteca oecocordia Longino, 2007 (Hymenoptera, Formicidae. Essa interação foi observada em uma região de Cerrado sensu stricto, na Universidade Federal de São Carlos, UFSCar, Brasil. A. oecocordia é registrada pela primeira vez para o Brasil.

  11. Los Cuícatl de Acomiztli Netzahualcóyotl: entre el ritual y la estética del pueblo Nahual

    OpenAIRE

    Carlos Daniel Ortiz Caraballo

    2016-01-01

    Este artículo muestra el aspecto literario de uno de las culturas más desarrolladas del México antiguo: el pueblo azteca - náhuatl. Para este caso, se consideran los Cuícatl de Acomiztli (1402-1469). Su objetivo es develar los temas que sustentan la lírica de este príncipe de la cultura azteca - náhuatl. Para ello, se ha considerado una interpretación de los escritos desde la antropología literaria, que entiende el texto como fragmento de una cultura, por lo que el centro del análisis lo cons...

  12. Milho verde: avaliação da resistência à lagarta da espiga, da espessura do pericarpo e outras características agronômicas Green corn: evaluation of earworm resistance, pericarp thickness and other agronomic characters

    Directory of Open Access Journals (Sweden)

    Eduardo Sawazaki

    1990-01-01

    Full Text Available Em Pariquera-Açu, SP, em maio de 1987, foi plantado um ensaio com o objetivo de avaliar as variedades IAC Azteca Centenário, IAC Maya Latente, IAC-1 e IAC-VD 2 e dois híbridos comerciais de milho verde, Agroceres 162 e Cargill 742, quanto à resistência à lagarta da espiga, espessura do pericarpo do grão e outros caracteres de importância agronômica. O ataque da lagarta foi avaliado utilizando-se a escala modificada por Widstrom e a contagem do furo de saída da lagarta. A espessura do pericarpo, medida através de um relógio comparador, foi retirada de duas posições de grãos embebidos em solução de glicerol e de uma posição em grãos secos. Outros caracteres agronômicos estudados foram: germinação e vigor das sementes usadas; estande final; altura da planta e da espiga; porcentagem de palha na espiga; número, rendimento, peso total e peso médio das espigas comerciáveis; peso de grãos e resistência a Exserohilum turticum (Pass. Leonard e Suggs. As variedades, com exceção da IAC-VD 2, apresentaram produção inferior aos híbridos. Quanto ao ataque do E. turcicum, o Cargill 742, IAC-VD 2 e IAC Maya Latente foram resistentes, e 'Agroceres 162', intermediário, 'IAC-1' e IAC Azteca Centenário', suscetíveis. Os resultados obtidos pelos métodos de avaliação do ataque da lagarta da espiga - a escala de Widstrom e a contagem do furo de saída - foram equivalentes na discriminação dos genótipos. A 'IAC Azteca Centenária foi a mais resistente e a IAC Maya Latente, a mais suscetível. A espessura do pericarpo variou entre os genótipos, sendo maior no 'Agroceres 162' e IAC Azteca Centenário'.The varieties IAC Azteca Centenário, IAC Maya Latente, IAC-1 and IAC-VD 2 and the hybrid Cargill 742 and Agroceres 162 were evaluated for resistance to corn earworm, pericarp thickness and other agronomic characters, in a trial planted at May 1987 in the Pariquera-Açu Experimental Station, State of São Paulo, Brazil. The earworm

  13. A new name for the Neotropical genus Aniarella Enderlein (Diptera, Sciaridae

    Directory of Open Access Journals (Sweden)

    Hüseyin Özdikmen

    2011-03-01

    Full Text Available A new name for the Neotropical genus Aniarella Enderlein (Diptera, Sciaridae. A junior homonym was detected among neotropical sciarid flies genera and the following replacement name is proposed: Novaniarella nom. nov. for Aniarella Enderlein, 1911 (nec Bolivar, 1906. Accordingly, new combinations are herein proposed for the species currently included in this genus: Novaniarella azteca (Lane, 1959 comb. nov., Novaniarella brevis (Rubsaamen, 1894 comb. nov. and Novaniarella pelluscens (Enderlein, 1911 comb. nov.

  14. Two myrmecophilous scale insects, Cryptostigma urichi (Cockerell (Hemiptera, Coccidae and Farinococcus multispinosus Morrison (Hemiptera, Pseudococcidae, cohabiting inside branches of Anadenanthera falcata (Benth. Speg. (Fabales, Fabaceae in the Cerrado area of São Paulo State, Brazil

    Directory of Open Access Journals (Sweden)

    André R. Nascimento

    2012-12-01

    Full Text Available The soft scale Cryptostigma urichi (Cockerell, 1894 and the mealybug Farinococcus multispinosus Morrison, 1922 are reported cohabiting inside branches of Anadenanthera falcata (Benth. Speg. (Angico-preto, both tended by the ant Azteca oecocordia Longino, 2007 (Hymenoptera, Formicidae. This interaction was observed in the Cerrado region sensu stricto, at the Federal University of São Carlos, UFSCar, Brazil. A. oecocordia is recorded for the first time in Brazil.

  15. El exilio artístico español en México

    OpenAIRE

    Cabañas Bravo, Miguel

    2009-01-01

    Estas páginas analizan la configuración y peculiaridades del exilio artístico español en México a raíz del desenlace de la guerra civil española y caracterizan y contextualizan el asiento e inscripción en el país azteca de los artistas españoles y su acción colectiva.

  16. Las creencias, los conflictos y las coyunturas que han estado impidiendo la representatividad y la gobernabilidad sostenible en M??xico

    OpenAIRE

    Garc??a Lirios, Cruz

    2008-01-01

    Durante los siglos XVI al XXI de la historia de M??xico se han estado desarrollando ocho creencias que activaron conflictos y formaron coyunturas. Las creencias m??sticas prehisp??nicas (indicadas por la desesperanza azteca), las creencias religiosas coloniales (indicadas por la evangelizaci??n ind??gena), las creencias avasalladoras coloniales (indicadas por la explotaci??n ??tnica), las creencias nacionalistas independentistas (indicadas por la identidad mestiza), las creencias liberales po...

  17. High diversity and low specificity of chaetothyrialean fungi in carton galleries in a neotropical ant-plant association.

    Directory of Open Access Journals (Sweden)

    Maximilian Nepel

    Full Text Available New associations have recently been discovered between arboreal ants that live on myrmecophytic plants, and different groups of fungi. Most of the - usually undescribed - fungi cultured by the ants belong to the order Chaetothyriales (Ascomycetes. Chaetothyriales occur in the nesting spaces provided by the host plant, and form a major part of the cardboard-like material produced by the ants for constructing nests and runway galleries. Until now, the fungi have been considered specific to each ant species. We focus on the three-way association between the plant Tetrathylacium macrophyllum (Salicaceae, the ant Azteca brevis (Formicidae: Dolichoderinae and various chaetothyrialean fungi. Azteca brevis builds extensive runway galleries along branches of T. macrophyllum. The carton of the gallery walls consists of masticated plant material densely pervaded by chaetothyrialean hyphae. In order to characterise the specificity of the ant-fungus association, fungi from the runway galleries of 19 ant colonies were grown as pure cultures and analyzed using partial SSU, complete ITS, 5.8S and partial LSU rDNA sequences. This gave 128 different fungal genotypes, 78% of which were clustered into three monophyletic groups. The most common fungus (either genotype or approximate species-level OTU was found in the runway galleries of 63% of the investigated ant colonies. This indicates that there can be a dominant fungus but, in general, a wider guild of chaetothyrialean fungi share the same ant mutualist in Azteca brevis.

  18. Differential host use in two highly specialized ant-plant associations: evidence from stable isotopes.

    Science.gov (United States)

    Trimble, S T; Sagers, C L

    2004-01-01

    Carbon and nitrogen stable isotopes were used to examine variation in ant use of plant resources in the Cecropia obtusifolia / Azteca spp. association in Costa Rica. Tissue of ants, host plants and symbiotic pseudococcids were collected along three elevation transects on the Pacific slope of Costa Rica's Cordillera Central, and were analyzed for carbon and nitrogen isotopic composition. Worker carbon and nitrogen signatures were found to vary with elevation and ant colony size, and between Azteca species groups. Ants in the A. constructor species group appear to be opportunistic foragers at low elevations, but rely more heavily on their host plants at high elevations, whereas ants in the A. alfari species group consume a more consistent diet across their distribution. Further, isotope values indicate that both ant species groups acquire more nitrogen from higher trophic levels at low elevation and when ant colonies are small. Provisioning by the host is a substantial ecological cost to the interaction, and it may vary, even in a highly specialized association. Nonetheless, not all specialized interactions are equivalent; where interaction with one ant species group appears conditional upon the environment, the other is not. Differential host use within the Cecropia-Azteca association suggests that the ecological and evolutionary benefits and costs of association may vary among species pairs.

  19. Ant species confer different partner benefits on two neotropical myrmecophytes.

    Science.gov (United States)

    Frederickson, Megan E

    2005-04-01

    The dynamics of mutualistic interactions involving more than a single pair of species depend on the relative costs and benefits of interaction among alternative partners. The neotropical myrmecophytes Cordia nodosa and Duroia hirsuta associate with several species of obligately symbiotic ants. I compared the ant partners of Cordia and Duroia with respect to two benefits known to be important in ant-myrmecophyte interactions: protection against herbivores provided by ants, and protection against encroaching vegetation provided by ants. Azteca spp., Myrmelachista schumanni, and Allomerus octoarticulatus demerarae ants all provide the leaves of Cordia and Duroia some protection against herbivores. However, Azteca and Allomerus provide more protection than does Myrmelachista to the leaves of their host plants. Although Allomerus protects the leaves of its hosts, plants occupied by Allomerus suffer more attacks by herbivores to their stems than do plants occupied by other ants. Relative to Azteca or Allomerus, Myrmelachista ants provide better protection against encroaching vegetation, increasing canopy openness over their host plants. These differences in benefits among the ant partners of Cordia and Duroia are reflected in the effect of each ant species on host plant size, growth rate, and reproduction. The results of this study show how mutualistic ant partners can differ with respect to both the magnitude and type of benefits they provide to the same species of myrmecophytic host.

  20. Los Cuícatl de Acomiztli Netzahualcóyotl: entre el ritual y la estética del pueblo Nahual

    Directory of Open Access Journals (Sweden)

    Carlos Daniel Ortiz Caraballo

    2016-01-01

    Full Text Available Este artículo muestra el aspecto literario de uno de las culturas más desarrolladas del México antiguo: el pueblo azteca - náhuatl. Para este caso, se consideran los Cuícatl de Acomiztli (1402-1469. Su objetivo es develar los temas que sustentan la lírica de este príncipe de la cultura azteca - náhuatl. Para ello, se ha considerado una interpretación de los escritos desde la antropología literaria, que entiende el texto como fragmento de una cultura, por lo que el centro del análisis lo constituye el sujeto creador y su interacción con el entorno. De esa forma, se parte de conceptos, tales como: cultura náhuatl, cuícatl y visión de mundo religiosa, entre otros. Con ello, se busca exteriorizar, tanto el mensaje de libertad y esperanza que plasmó el cuicapicqui (forjador de cantos prehispánico en sus Cuícatl, como la contribución del pueblo azteca náhuatl a las letras latinoamericanas.

  1. Ocorrência de moluscos límnicos e crustáceo em macroaglomerados do mexilhão dourado, Limnoperna fortunei (Dunker, 1857 sobre sarandi no lago Guaíba (RS, Brasil

    Directory of Open Access Journals (Sweden)

    Maria Cristina Dreher Mansur

    2008-01-01

    amostras; Potamolithus jacuhyensis Pilsbry, 1899 (35,71%, como espécie acessória e o crustáceo Hyalella curvispina Shoemaker, 1942 (26%, como espécie acessória. Os demais táxons foram acidentais (<25%: Ampullariidae (indivíduos jovens; Heleobia davisi (Silva & Thomé, 1985; Chilina parva (Martens, 1868 e Corbicula fluminea (Müller, 1774. As relações interespecíficas destes táxons são até o momento pouco conhecidas.

  2. Dos libros

    Directory of Open Access Journals (Sweden)

    Ernesto Camargo Martínez

    1961-09-01

    Full Text Available El documento presenta las reseñas de los títulos: -OCTAVIO AMORTEGUI. Nubes de Antaño. (1946-1960. México. 1961. Editado en la Impresora Azteca. -El problema religioso en la moderna novela española. Por la Madre María Luis Negueruela Escribano A. C. l. (Tesis de grado presentada para optar el título de doctor en Filosofía y Letras en la Pontificia Universidad Católica Javeriana de Bogotá. 1960.

  3. Inventario de la fauna de hormigas de San Andrés Isla (Colombia

    Directory of Open Access Journals (Sweden)

    Fernández Fernando

    2006-06-01

    Full Text Available En este documento se registra por primera vez información parcial del inventario de las hormigas de San Andrés Isla. Se presenta a continuación un listado de los géneros y se proponen claves ilustradas para subfamilias, tribus y géneros. En total se encontraron 24 géneros: Azteca, Linepithema y Tapinoma de la subfamilia Dolichoderinae; Camponotus, Brachymyrmex y Paratrechina de Formicinae; Pseudomyrmex de Pseudomyrmecinae; Hypoponera, Leptogenys, Odontomachus, Pachycondyla y Platythyrea de Ponerinae; Ectatomma de Ectatomminae y de Myrmicinae: Cyphomyrmex, Wasmannia, Crematogaster, Pyramica, Strumigenys, Cardiocondyla, Pheidole, Monomorium, Solenopsis, Rogeria y Tetramorium.

  4. Estudio de un cemento de las ruinas de Teotihuacan

    Directory of Open Access Journals (Sweden)

    Goldschimdt, A.

    1981-06-01

    Full Text Available Not available

    Se estudió un mortero de cemento portland de aproximadamente 30 años expuesto a la intemperie y otro mortero de las ruinas de Teotihuacan, mediante Microsonda (EM y Microscopía Electrónica de Barrido (SEM. Mostrándose la diferencia entre ambos morteros y evidenciando la semejanza, del de Teotihuacan -cuya edad es anterior a la conquista del Imperio Azteca- con el mortero puzolánico Romano.

  5. Espectros de la ciudad de México

    OpenAIRE

    2009-01-01

    "Espectros del DF" aborda el tema del discurso urbano bajo la perspectiva del simulacro. Una de las ciudades más grandes del mundo, México, DF, difícil de abarcar como entorno físico, se define cotidianamente por las representaciones que de ella hacen sus habitantes. Esto se remonta a la imagen fundadora que persiguieron los aztecas (el águila devorando una serpiente) y llega hasta los posibles contactos con extraterrestres. Las imágenes de la ciudad la traducen en otra, que responde a una ló...

  6. EL QUEHACER DE LAS INSTITUCIONES DE EDUCACIÓN SUPERIOR ANTE EL PANORAMA MUNDIAL DEL CONSUMO DE DROGAS

    Directory of Open Access Journals (Sweden)

    Xóchitl De San Jorge

    2016-07-01

    Full Text Available Existen evidencias que documentan el uso ritual, religioso, médico y hedonista de distintas drogas desde los tiempos más remotos. Asimismo, sabemos que en la antigüedad existía una percepción de riesgo del libre consumo de drogas que derivó en la prohibición o restricción -para cierto sector de la población y para determinadas ocasiones- como en el caso del alcohol en el imperio azteca o del tabaco en la Europa del siglo XVI.

  7. El papel de la vestimenta en los rituales mexicas de “personificación”

    OpenAIRE

    Dehouve, Danièle

    2016-01-01

    Los mexicas o aztecas del centro de México utilizaban en sus ceremonias ciertas prendas de vestir tejidas de algodón o de fibras vegetales, o simplemente hechas de papel de amate, y cubiertas de diseños. El presente artículo procura explicar la variedad de dicha indumentaria ritual con la ayuda del concepto nativo de “personificación” (ixiptla, en náhuatl), en función del cual se cubría un soporte (el “personificador”) con una indumentaria y varios adornos pertenecientes a un dios (el “person...

  8. El cuento en Colombia

    Directory of Open Access Journals (Sweden)

    Eduardo Pachón Padilla

    1965-02-01

    Full Text Available Se ha dicho que el origen del cuento americano debe buscarse en los antiguos relatos de los aborígenes, que después del Descubrimiento, algunos cronistas españoles de los siglos XVI y XVII, transcribieron en lengua romance. Posiblemente también los chibchas, como los mayas, los aztecas y los incas, se entretuvieron en relatos de esparcimiento narrando sucesos de carácter mítico, hazañas de guerreros, prodigios mágicos, etcétera, pero ellos todavía permanecen casi ignorados.

  9. El antiguo festival céltico pagano de Samain y su continuación en la fiesta laica de Halloween, el día de los difuntos cristiano y el día de muertos en México

    Directory of Open Access Journals (Sweden)

    Manuel Alberro

    2004-01-01

    Full Text Available En el artículo se analiza la festividad mexicana del Día de Muertos, sus raícesparciales en la Festividad de los Muertos de los antiguos aztecas, y la forma en quese desarrolló a partir del Día de los Difuntos cristiano, cuyo origen se retrotrae a suvez a la antigua festividad céltica pagana de Samain. Se estudia también la recienteintroducción en México de la actual fiesta laica de Halloween, derivada asimismo deSamain, y la forma en la que los mexicanos reaccionan ante este acontecimiento.

  10. El Gueguense primer personaje del teatro latinoamericano

    OpenAIRE

    Galich, Manuel

    2012-01-01

    El centro geográfico de la vigorosa cultura náhuatl fue, como lo dice la palabra, el Anáhuac, es decir el Valle de México, y a su esplendor contribuyeron, sucesiva y no exclusivamente, teotihuacanos, toltecas y aztecas. Otras naciones, como la tlaxcalteca y la tezcocana, también enriquecieron aquella cultura, además de lejanas influencias de orígenes diversos. Por ejemplo, la olmeca. A su vez, dicha cultura irradio en un ámbito amplísimo, que comprendió toda la costa sudoccidental del Istmo d...

  11. La industria de la telenovela mexicana: procesos de comunicación, documentación y comercialización

    OpenAIRE

    Barron Domínguez, Leticia

    2009-01-01

    En México, la telenovela constituye uno de los productos audiovisuales que mayores ingresos ha generado a la industria audiovisual del sector, tanto por sus ventas nacionales como por sus exportaciones. Actualmente en el país existen dos productoras de este género televisivo, con cadenas de televisión abierta, que tienen cobertura de transmisión a nivel nacional: Televisa y TV Azteca. Ambas operan con capital mexicano. Este género audiovisual, heredero del melodrama del siglo XVIII, ha manten...

  12. Las Ideas Psicológicas en Colombia

    OpenAIRE

    1999-01-01

    El interés en los problemas que hoy llamamos psicológicos se encuentra en todas las grandes civilizaciones. En América existieron importantes ideas psicológicas en los Mayas, Aztecas, Incas y en los pobladores de la actual Colombia. La psicología en su conceptualización moderna comienza en 1879 con la fundación del primer Laboratorio de Psicología Experimental en la Universidad de Leipzig por obra de W. Wundt. Hoy la psicología como disciplina es tanto una ciencia como una profesión, y tanto ...

  13. La enfermedad y la medicina en las culturas precolombinas de América: la cosmovisión nahua

    OpenAIRE

    Sergio Javier Villaseñor Bayardo; Carlos Rojas Malpica; Carlos E. Berganza Champagnac

    2002-01-01

    Los autores de este trabajo presentan algunos datos históricos relativos a la enfermedad y a la medicina en las culturas precolombinas de América. Se explican algunas teorías sobre el poblamiento original de América: Arias Montano, Florentino Ameghino, Ales Hrdlicka, Paul Rivet. Se abordan algunos aspectos de las culturas precolombinas del continente: la cultura chibcha, la incaica, los caribes y arahuacos, la azteca y la maya. Se explican las principales características de la medicina nahua ...

  14. El antiguo festival céltico pagano de Samain y su continuación en la fiesta laica de Halloween, el día de los difuntos cristiano y el día de muertos en México

    OpenAIRE

    Manuel Alberro

    2004-01-01

    En el artículo se analiza la festividad mexicana del Día de Muertos, sus raícesparciales en la Festividad de los Muertos de los antiguos aztecas, y la forma en quese desarrolló a partir del Día de los Difuntos cristiano, cuyo origen se retrotrae a suvez a la antigua festividad céltica pagana de Samain. Se estudia también la recienteintroducción en México de la actual fiesta laica de Halloween, derivada asimismo deSamain, y la forma en la que los mexicanos reaccionan ante este acontecimiento....

  15. 这个人能讨工人喜欢吗?

    Institute of Scientific and Technical Information of China (English)

    ElisabethMalkin; 朱洪; 叶曲

    1998-01-01

    理卡多·萨利纳斯·裴雷戈周身上下一副墨西哥超级富豪的派头。他出入乘坐自己的直升机,在科罗拉多州的威尔滑雪,在击墨西哥城中他的阿斯特卡电视台(TV Azteca)办公室上班途中身边有10名保镖侍卫左右以防不测。

  16. La cartografía como relato : Intervenir los mapas, narrar las ciudades

    OpenAIRE

    López Parada, Esperanza

    2014-01-01

    El misterio que rodea el mapa de la primera ciudad imperial azteca, publicado en la traducción latina de la Segunda Carta de Relación de Hernán Cortés –su origen, su orientación, su autoría, su sentido–, se ve acompañado por los cambios que, con un claro sesgo ideológico, introducen las reproducciones posteriores en las imprentas de toda Europa. Si no resultan menos enigmáticos los rasgos que, en cambio, permanecen inalterados, tampoco arrojan luz sus nuevos empleos, independizándose ya de la...

  17. Seasonal trophic activity of the aquatic morphotype of Atelognathus patagonicus (Anura, Neobatrachia and prey availability in the littoral benthos of a permanent pond in Argentinean Patagonia

    Directory of Open Access Journals (Sweden)

    María Elena Cuello

    2009-12-01

    Full Text Available The diet of the aquatic morphotype of Atelognathus patagonicus was studied in frogs collected from the Laguna Verde pond (Laguna Blanca National Park, Neuquén, Argentina. The content of 35 gastrointestinal tracts of post-metamorphic specimens from November 2003 to April 2006 was related to the composition of the benthos in their microhabitat. Number, size, occurrence and relative importance of preys, diversity of the diet, trophic niche breadth and electivitywere estimated for each season of the year. The diet consisted of aquatic arthropods. The composition of both the benthos and the food (number and occurrence of organisms in the diet were dominated by the amphipod Hyalella sp. The relative importance (IRI of Hyalella sp. in the diet was over 99% in summer and autumn, and 100% in winter and spring. Diptera and Copepoda in summer, and Dytiscidae and Ostracoda in autumn, had seasonal IRI values ≤ 0.2%. Trophic niche breadth was very low in summer and autumn, and null (= 0 in winter and spring. The mean number of preys per individual was highest in spring (19 preys/frog and lowest in winter (4 preys/frog. Frogs continued with their trophic activity in winter, even when the surface of the pond was frozen. There is a correspondence between the frogs’ main food item and its presence in the benthos.

  18. Basal temperature and thermal sum in phenological phases of nectarine and peach cultivars

    Directory of Open Access Journals (Sweden)

    Adilson Pacheco de Souza

    2011-12-01

    Full Text Available The objective of this work was to evaluate basal temperature, thermal sum at different phenological stages, phenological phase duration, yield and seasonality of one nectarine and 14 peach cultivars, between 2006 and 2009. The considered phenological phases were: pruning-sprouting; sprouting-flowering, from swollen bud to open flower; flowering-fruiting, from petal fall to medium-sized fruit; and ripening. Minimum basal temperatures (Tb obtained were: pruning-sprouting, 8°C, irrespective of the cultivars; sprouting-flowering, 10°C, except for 'Cascata 968', which required 8°C Tb; flowering-fruiting, 12°C, except for 'Oro Azteca', which required 14°C Tb; ripening, 14°C, except for 'Sunblaze', 'Diamante Mejorado' and 'Precocinho' with 12°C Tb. For most cultivars, the maximum basal temperatures were 30, 34, 34 and 28ºC for phases pruning-sprouting, sprouting-flowering, flowering-fruiting and ripening, respectively. 'Turmalina', 'Marli' and 'Tropic Beauty' showed average yields of 3,945.0, 3,969.3 and 3,954.0 kg ha-1, respectively, in 2009, while the nectarine 'Sunblaze' showed around 3,900 kg ha-1 in 2008 and 2009. The cultivars differed for their total cycle and for the accumulated thermal sums which varied, respectively, from 245 days and 1,881.4 degree-days for 'Oro Azteca', to144 days and 1,455.7 degree-days for 'Precocinho'.

  19. Data for comparative proteomics of ovaries from five non-model, crustacean amphipods

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    Judith Trapp

    2015-12-01

    Full Text Available Ovaries were taken from five sexually mature amphipods: Gammarus fossarum, Gammarus pulex, Gammarus roeseli, Hyallela azteca and Parhyale hawaiensis. The soluble proteome extracted from individual pair of ovaries from five biological replicates was trypsin digested and the resulting peptides were analyzed by high resolution tandem mass spectrometry. The spectra were assigned with four protein sequence databases with different specificities: a RNAseq-derived G. fossarum database; a RNAseq-derived P. hawaiensis database; both originating from ovaries transcriptome; the Daphnia pulex database derived from whole-genome sequencing and the NCBInr database. The best interpretation was obtained for most animals with the specific RNA-seq protein database previously established by means of RNAseq carried out on G. fossarum. Proteins identified in the five amphipod species allow defining the core-proteome of female reproductive tissues of the Senticaudata suborder. The data accompanying the manuscript describing the database searches and comparative analysis Trapp et al., 2015 [1] have been deposited to the ProteomeXchange with identifiers PXD002253 (G. fossarum, PXD002254 (G. pulex, PXD002255 (G. roeseli, PXD002256 (H. Azteca, and PXD002257 (P. hawaiensis.

  20. Spider diversity in coffee agroecosystems: the influence of agricultural intensification and aggressive ants.

    Science.gov (United States)

    Marín, Linda; Perfecto, Ivette

    2013-04-01

    Spiders are a very diverse group of invertebrate predators found in agroecosystems and natural systems. However, spider distribution, abundance, and eventually their ecological function in ecosystems can be influenced by abiotic and biotic factors such as agricultural intensification and dominant ants. Here we explore the influence of both agricultural intensification and the dominant arboreal ant Azteca instabilis on the spider community in coffee agroecosystems in southern Mexico. To measure the influence of the arboreal ant Azteca instabilis (F. Smith) on the spider community inhabiting the coffee layer of coffee agroecosystems, spiders were collected from coffee plants that were and were not patrolled by the ant in sites differing in agricultural intensification. For 2008, generalized linear mixed models showed that spider diversity was affected positively by agricultural intensification but not by the ant. However, results suggested that some spider species were associated with A. instabilis. Therefore, in 2009 we concentrated our research on the effect of A. instabilis on spider diversity and composition. For 2009, generalized linear mixed models show that spider richness and abundance per plant were significantly higher in the presence of A. instabilis. In addition, analyses of visual counts of insects and sticky traps data show that more resources were present in plants patrolled by the ant. The positive effect of A. instabilis on spiders seems to be caused by at least two mechanisms: high abundance of insects and protection against predators.

  1. Breaking Barriers: An Asian-American Curriculum Unit.

    Science.gov (United States)

    Brombach, Catherine; Tice, Natasha Florey

    A 10-day curriculum is presented for upper elementary grades to explore who is in power on the local, state, and federal levels; and to investigate why so few Asian Americans are in power; and to confront personal prejudices and break stereotypes about Asian Americans. The 10 days are devoted to the following: (1) distinguishing between prejudice…

  2. Determining the long-term effect of antibiotic administration on the human normal intestinal microbiota using culture and pyrosequencing methods

    NARCIS (Netherlands)

    Rashid, M.U.; Zaura, E.; Buijs, M.J.; Keijser, B.J.F.; Crielaard, W.; Nord, C.E.; Weintraub, A.

    2015-01-01

    The purpose of the study was to assess the effect of ciprofloxacin (500 mg twice daily for 10 days) or clindamycin (150 mg 4 times daily for 10 days) on the fecal microbiota of healthy humans for a period of 1 year as compared to placebo. Two different methods, culture and microbiome analysis, were

  3. Classical Conditioning and Retention of the Infant's Eyelid Response: Effects of Age and Interstimulus Interval.

    Science.gov (United States)

    Little, Arlene H.; And Others

    1984-01-01

    Reports that lengthy interstimulus interval facilitates classical conditioning in very young infants. Infants trained in a single session at 20 days of age exhibited reliable retention of the conditioned eyelid reflex 10 days later, but infants 10 days of age did not. (Author)

  4. Glucocorticoids for Duchenne Muscular Dystrophy

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2013-07-01

    Full Text Available Investigators at the Dubowitz Neuromuscular Centre, Great Ormond Street Hospital, and other centers in the UK, conducted a prospective longitudinal study across 17 neuromuscular centers in the UK of 360 boys aged 3-15 years with Duchenne muscular dystrophy who were treated with daily or intermittent (10 days on/10 days off prednisolone for a mean duration of 4 years.

  5. Experiment list: SRX109457 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available musculus; ChIP-Seq source_name=EB cells cultured with a hematopietic cytokine cocktail for 10 days || cell ...type=EB cells cultured with a hematopietic cytokine cocktail for 10 days || chip antibody=anti-HoxB4 || chip

  6. Experiment list: SRX109458 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available s musculus; ChIP-Seq source_name=EB cells cultured with a hematopietic cytokine cocktail for 10 days || cell... type=EB cells cultured with a hematopietic cytokine cocktail for 10 days || chip antibody=none || chip anti

  7. Determining the long-term effect of antibiotic administration on the human normal intestinal microbiota using culture and pyrosequencing methods

    NARCIS (Netherlands)

    Rashid, M.U.; Zaura, E.; Buijs, M.J.; Keijser, B.J.F.; Crielaard, W.; Nord, C.E.; Weintraub, A.

    2015-01-01

    The purpose of the study was to assess the effect of ciprofloxacin (500 mg twice daily for 10 days) or clindamycin (150 mg 4 times daily for 10 days) on the fecal microbiota of healthy humans for a period of 1 year as compared to placebo. Two different methods, culture and microbiome analysis, were

  8. El Centro Histórico de la Ciudad de México al Inicio del Siglo XXI

    Directory of Open Access Journals (Sweden)

    Alejandro Suárez Pareyón

    2004-01-01

    Full Text Available La Ciudad de México tiene un centro cuyo origen se remonta a la ciudad azteca fundada hace siete siglos y los conquistadores españoles refundaron la ciudad conservando la esencia del principio ordenador prehispánico, la riqueza acumulada a lo largo de la historia se manifiesta en la gran concentración de sitios y edificios que le han significado el reconocimiento internacional de Patrimonio de la Humanidad. El Centro Histórico es un reflejo de toda la heterogeneidad social, económica y cultural que representa una de las más grandes metrópolis del mundo, es un espacio urbano lleno de contrastes en donde el gobierno de la ciudad ha emprendido un proceso de planificación urbana para la regeneración integral de las funciones que le han sido representativas a lo largo de la historia.

  9. Loyolanthidium gen. n. e três espécies novas neotropicais (Hymenoptera, Megachilidae Loyolanthidium gen. n. and three new neotropical species (Hymenoptera, Megachilidae

    Directory of Open Access Journals (Sweden)

    Danúncia Urban

    2001-03-01

    Full Text Available Loyolanthidium gen. n. (type species: Anthidium apicale Cresson, 1878 is proposed to accommodate the western hemisphere species hitherto placed by the authors in Anthidiellum Cockerell, 1904. Three new species are described: Loyolanthidium bolivianum sp. n. (from Bolívia, Loyolanthidium azteca sp. n. and Loyolanthidium xilitlense sp. n. (both from México. The following nomenclatural changes are introduced: Loyolanthidium apicale (Cresson, 1878 comb. n. = Anthidium albopilosum Friese, 1910 syn. n. = Anthidium auricolle Friese, 1921 syn. n.; Loyolanthidium ehrhorni (Cockerell, 1900 comb, n.; Loyolanthidium gilense (Cockerell, 1897 comb, n.; Loyolanthidium notatum (Latreille, 1809 comb, n.; Loyolanthidium perplexum (Smith, 1854 comb, n.; Loyolanthidium robertsoni (Cockerell, 1904 comb. n. and Loyolanthidium toltecum (Cresson, 1878 comb. n.

  10. Spatial pattern and ecological process in the coffee agroforestry system.

    Science.gov (United States)

    Perfecto, Ivette; Vandermeer, John

    2008-04-01

    The coffee agroforestry system provides an ideal platform for the study of spatial ecology. The uniform pattern of the coffee plants and shade trees allows for the study of pattern generation through intrinsic biological forces rather than extrinsic habitat patchiness. Detailed studies, focusing on a key mutualism between an ant (Azteca instabilis) and a scale insect (Coccus viridis), conducted in a 45-ha plot in a coffee agroforestry system have provided insights into (1) the quantitative evaluation of spatial pattern of the scale insect Coccus viridis on coffee bushes, (2) the mechanisms for the generation of patterns through the combination of local satellite ant nest formation and regional control from natural enemies, and (3) the consequences of the spatial pattern for the stability of predator-prey (host-parasitoid) systems, for a key coccinelid beetle preying on the scale insects and a phorid fly parasitoid parasitizing the ant.

  11. Inkarrí y el mesianismo andino

    OpenAIRE

    Ossio, Juan M.

    2013-01-01

    Note portant sur l’auteur La región vertebrada por la cordillera de los Andes en contraste con Mesoamérica fue el escenario de uno de los intentos de dominación y unificación política más exitosos de toda la América precolombina. Se trata de lo que hoy se conoce como “imperio de los incas”. A diferencia de los logros alcanzados por algunas culturas mesoamericanas que le fueron contemporáneas, como los aztecas o los mayas, el último Estado que se desarrolló en los Andes antes de la presencia e...

  12. Vida y obra de Don Juan Suárez de Peralta : cronista y protoalbéytar de América : el hombre de las dos España (1541-1613)

    OpenAIRE

    Miguel A Márquez

    2016-01-01

    Don Juan Suárez de Peralta nació en la ciudad de México-Tenochtitlán en 1541, habiendo sido sus padres Don Juan Suárez Marcayda y Doña Magdalena de Peralta; el padre también conocido como Juan Suárez de Ávila, o como Juan Suárez “El Viejo”, hizo la campaña militar de la conquista del Imperio Azteca como compañero de armas de Don Hernán Cortés. Suárez de Peralta escribió tres grandes obras: “Tractado de Alveiteria” hacia 1575, “Tractado de Cavallería de la Gineta y Brida” en ...

  13. Diversity and effective population size of four horse breeds from microsatellite DNA markers in South-Central Mexico

    Directory of Open Access Journals (Sweden)

    J. F. Vázquez-Armijo

    2017-06-01

    Full Text Available The South-Central region of Mexico has experienced a sizeable introduction of purebred horses for recreational aims. A study was designed to assess effective population sizes and genetic diversity and to verify the genetic integrity of four horse breeds. Using a 12-microsatellite panel, Quarter Horse, Azteca, Thoroughbred and Creole (CRL horses were sampled and analysed for diversity and genetic structure. Genetic diversity parameters showed high numbers of heterozygous horses but small effective population sizes in all breeds. Population structure results suggested some degree of admixture of CRL with the other reference breeds. The highly informative microsatellite panel allowed the verification of diversity in introduced horse populations and the confirmation of small effective population sizes, which suggests a risk for future breed integrity.

  14. Monumento funerario

    Directory of Open Access Journals (Sweden)

    Artigas, Francisco

    1959-12-01

    Full Text Available He aquí una bella muestra de arquitectura aplicada al tema del "Monumento Conmemorativo". Pero, además, al difícil monumento funerario, que tan desastrosos ejemplos de mal gusto ofrece a la vista de cualquier visitante de panteones en el mundo y, muy especialmente, en el mundo latino. La vanidad humana, llevada más allá de la muerte, se plasma en pequeños templos barrocos, neoclásicos y hasta aztecas, negación de todo sentido de proporción arquitectónica y un motivo más para amar la vida y temer la muerte.

  15. COMO OS NATIVOS AMERICANOS TERIAM UTILIZADO SEUS ESPELHOS?

    OpenAIRE

    Lunazzi,José Joaquín

    2015-01-01

    Dois mil anos antes da chegada dos europeus, civilizações americanas contavam com espelhos capazes de fornecer boa qualidade de imagem. Notadamente, a Olmeca em Centroamérica, mas também a Cupisnique na América do Sul. Essa tecnologia óptica pode ter influenciado nos Maias e até nos Aztecas, embora saibamos que sua aplicação e difusão aparece como muito restrita. Porém ligada a relações de poder e representada em divindades. Por achados, pode-se ter uma ideia da técnica de sua realização mas,...

  16. Adán, el Edén y Abel o la estructura narrativa simbólica de las Cartas de relación de Hernán Cortés

    OpenAIRE

    Robles Mohs, Ivonne

    2015-01-01

    Diferentes trabajos sobre la narrativa colonial y en la cultura de símbolos se sistematizaron para determinar la especificidad de la estructura narrativa en Cartas de Relación. En particular, el autor ilustra cómo Cartas de Relación, como simbólico, la práctica significativa, se indicará el blanco frente. Disyunción india en virtud de la acción pacificadora y de la población que, en nombre de la Cruz, Cortés emprende en el espacio cultural azteca y en particular en Tenochtitlán. También se il...

  17. Adán, el Edén y Abel o la estructura narrativa simbólica de las Cartas de relación de Hernán Cortés

    OpenAIRE

    Robles Mohs, Ivonne

    2015-01-01

    Diferentes trabajos sobre la narrativa colonial y en la cultura de símbolos se sistematizaron para determinar la especificidad de la estructura narrativa en Cartas de Relación. En particular, el autor ilustra cómo Cartas de Relación, como simbólico, la práctica significativa, se indicará el blanco frente. Disyunción india en virtud de la acción pacificadora y de la población que, en nombre de la Cruz, Cortés emprende en el espacio cultural azteca y en particular en Tenochtitlán. También se il...

  18. 阿尔卡特朗讯联手哥伦比亚Azteca部署国家宽带网络

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    日前,阿尔卡特朗讯宣布联手哥伦比亚领先的通信业务供应商Azteca(Azteca Comunicaciones Colombia)共同建设国家宽带网络工程。阿尔卡特朗讯将作为该项目的主要供应商,帮助Azteca在全国753个市部署宽带网络,向数百万企业和个人用户,推出高清电视、视频、语音、高速数据传输等高品质业务。

  19. When attempts at robbing prey turn fatal.

    Science.gov