bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a short-term reproductive endocrine bioassay using steroid hormone and vitellogenin end points in the estuarine mummichog (Fundulus heteroclitus)
Authors: MacLatchy Deborah L. , Courtenay Simon C. , Rice Charles D. , Van Der Kraak Glen J.
Published: March 2010

We have developed a short-term gonadal recrudescence test with the estuarine mummichog (Fundulus heteroclitus) and determined endocrine end points sensitive to a strong estrogen agonist (ethynylestradiol; EE2) and an antiestrogen (ZM 189,154; ZM) at concentrations of 0 to 1,000 ng/L in three separate experiments. A protocol was developed to ensure a year-round supply of recrudescing fish. A protocol for determining steroid production (testosterone and 11-ketotestosterone [11-KT] in incubated testes tissue and testosterone and 17-estradiol [E2] in incubated prematurational follicles) was optimized. Recrudescing fish (males, gonadosomatic index = 2%; females = 10%) were exposed to graded doses of EE2 or ZM for 7 to 15 d using a static daily-renewal protocol. At high EE2 (>250 ng/L), the effect on males was depression of androgen steroidogenesis and plasma steroid levels. In females, high EE2 depressed gonadal production and circulating E2 levels; however, EE2 concentrations <100 ng/L caused increased gonadal production and plasma E2. Low ZM (<100 ng/L) had little effect on male and female fish, while higher concentrations (>250 ng/L) increased E2 and 11-KT production while decreasing plasma 11-KT and E2 (1,000 ng/L only). Male and female plasma vitellogenin responded in a concentration-dependent fashion to EE2 with no effect by ZM. The low observable effect concentrations for the endocrine parameters were 1 ng/L for EE2 and 250 ng/L for ZM. The bioassay and results encompassing the environmentally relevant exposure range (1–100 ng/L) will be useful for assessing effects of endocrine-active contaminants in estuarine environments.
Kinetics of benzene biodegradation by Pseudomonas aeruginosa: Parameter estimation
Authors: Kim Song-Bae , Park Choon-Hwa , Kim Dong-Ju , Jury William A.
Published: March 2010

This study determined the model parameters describing biodegradation of benzene by conducting kinetic microcosm batch tests in both pure solution and saturated aquifer material conditions for various initial benzene (100–700 mg/L) and microbial concentrations (107–109 colony-forming units [CFU]/ml) using Pseudomonas aeruginosa as benzene-degrading bacteria. In both tests, benzene and microbial concentrations were monitored over time in order to investigate which of two Monod kinetic equations, the Monod-with-growth or the Monod-no-growth model, was more suitable for describing benzene biodegradation and to estimate the associated model parameters. Parameter estimation was performed by fitting the numerical solution of each model obtained by the fourth-order Runge-Kutta integration to the measured data of benzene and/or microbial concentrations. For the Monod-with-growth model, the best fit of the numerical solution was significantly different than the measured benzene concentrations, especially at early times, because of the gradual increase of microbial population in the growth curve. In contrast, the solution based on the Monod-no-growth model produced reasonable agreement with the measured benzene data. The estimated parameters of maximum substrate utilization rate (kmax) and half-saturation constant (Kc) were in the range of 61 to 105 mg/L/d and about 270 mg/L, respectively, which differ significantly from values previously reported in the literature. We attribute the differences observed in our study to our experimental conditions of initial substrate and bacterial concentrations and oxygen and nutrient supply. Our results imply that an appropriate model type and reasonable values of kinetic parameters should be chosen to model the biodegradation of hydrocarbons in the subsurface environment.
Ecotoxicological responses of the mayflyBaetis tricaudatusto dietary and waterborne cadmium: Implications for toxicity testing
Authors: Irving Elaine C. , Baird Donald J. , Culp Joseph M.
Published: March 2010

Trace metals readily accumulated by stream periphyton may enter aquatic food chains through grazer ingestion. Hence, experiments were conducted to determine the ecotoxicological responses of the grazing mayfly Baetis tricaudatus to dietary cadmium. Short-term feeding experiments indicated that B. tricaudatus nymphs did not initially avoid grazing on cadmium-contaminated diatom mats. During a partial life-cycle experiment, 4 and 10 μg/g of dietary cadmium significantly inhibited grazing, whereas 10 μg/g significantly inhibited growth. Feeding inhibition was the likely mechanism that inhibited growth (i.e., through reduced energy intake). Conversely, when exposed to waterborne cadmium using lethal toxicity test procedures, B. tricaudatus nymphs were relatively tolerant (96-h median lethal concentration, 1,611 μg/L). Thus, sublethal responses to dietary exposure appeared to be more sensitive than lethal responses to waterborne exposure. Because adult mayfly fecundity is a function of nymph size at emergence, dietary cadmium exposure could increase the extinction probability within mayfly populations. The present study highlights the importance of dietary exposure routes in determining the ecotoxicological responses of an organism to a contaminant. Furthermore, the findings emphasize the advantage of evaluating a combination of ecologically relevant, lethal and sublethal endpoints in laboratory methods used to generate data for ecological risk assessment and regulation.
Toxic effects of polychlorinated biphenyl bio accumulation in sea urchins exposed to contaminated sediments
Authors: Zeng Eddy Y. , Bay Steven M. , Greenstein Darrin , Vista Cherrie , Yu Charlie , Ritter Kerry
Published: March 2010

The uptake patterns and toxicity of poly chlorinated biphenyl (PCB) congeners in the white sea urchin, Lytechinus pictus, on exposure to contaminated sediments were investigated. First-order modeling of uptake of the 10 most abundant PCB congeners or domains (containing more than one coeluting congener) by L. pictus indicated that a 35-d exposure was insufficient to reach steady state. Bioaccumulation of PCBs in sea urchins exhibited substantial difference between field and amended sediments, suggesting that caution must be exercised in sample preparation. Some evidence was observed of dependence of measured biota-sediment accumulation factors (BSAFs) on Kow, indicating that equilibrium partitioning of PCBs may not always be achieved between biota lipid, sediment organic carbon, and water. Survival of L. pictus was unaffected by exposure to field and amended sediments with PCB concentrations varying more than three orders of magnitude. The growth measures (diameter, wt, and gonad wt) were significantly reduced in L. pictus exposed to San Diego Bay ([SDB]; San Diego, CA, USA) sediment, whereas they were relatively unaffected after exposure to amended sediments (with much higher PCB concentrations than SDB sediment) prepared from a New Bedford Harbor (MA, USA) sediment. The toxic effects as measured by the growth rates in L. pictus were likely attributable to polycyclic aromatic hydrocarbons (PAHs), which were elevated in SDB sediment (7.3 μg/g), rather than PCBs.
A microcosm system for the study of pollution effects in shallow, sandy, subtidal communities
Authors: Suderman Keith , Thistle David
Published: March 2010

The introduction of pollutants into the marine environment is inevitable, so an understanding of their effects is needed. Because shallow, coastal waters are at greatest risk and many of these shorelines are sandy, a test system for the shallow, sandy, subtidal environment is required. We developed a microcosm system for this purpose and tested it for three months to determine whether the benthic community remained healthy. Furthermore, because long-term effects on the environment occur primarily in the sediment, an experimental method for administering pollutants to the sediment is necessary. We administered a 1-mm layer of clean sand (simulating a technique of administering pollutants as a coating on sand) and tested the benthic community for artifactual effects of the sand itself. Fifteen metrics of community health, including the abundance of benthic microalgae, nematodes, and copepods, were measured. Most metrics were not significantly affected either by containment in the microcosms or by the addition of a 1-mm layer of clean sand. These microcosms are suitable as a test system for the shallow, sandy, subtidal environment.
Availability of metals to the nematode Caenorhabditis elegans: Toxicity based on total concentrations in soil and extracted fractions
Authors: Boyd Windy A. , Williams Phillip L.
Published: March 2010

Current regulation of metals in soils is based on total metal concentrations rather than on actual exposure concentrations. Considering the extreme variation in soil physicochemical properties, total concentrations are not reflective of the availability and resultant toxicity of metals in different soils. In this study, the availability of Cd, Cu, Ni, Pb, and Zn to the free-living soil nematode Caenorhabditis elegans was assessed after 24-h exposures in three soils using a sequential soil extraction procedure. Albany soil, sampled from southern Georgia, USA, is characterized by a high sand content, whereas Cecil soil from the Piedmont region of Georgia contains higher fractions of clay and organic matter. The final soil was an American Society for Testing and Materials (ASTM) artificial medium composed of peat, kaolin clay, sand, and calcium carbonate. Based on their composition, ASTM medium would sorb metals most strongly and Albany soil the least strongly. In fact, 24-h lethal concentrations to 50% (LC50s) of nematodes for the five metals as determined by the total metal concentration followed this trend. In addition, water-extractable metals were lowest in ASTM medium and highest in Albany soil when spiked at the same concentrations. Our data show the need to consider soil type when performing toxicological tests and establishing site-specific allowable metal concentrations in soil.
1-hydroxypyrene glucuronide as the major aqueous pyrene metabolite in tissue and gut fluid from the marine deposit-feeding polychaete Nereis diversicolor
Authors: Giessing Anders M. B. , Mayer Lawrence M. , Forbes Thomas L.
Published: March 2010

Both 1-hydroxypyrene and 1-hydroxypyrene glucuronide are identified as the primary phase I and phase II metabolites of the four-ringed polycyclic aromatic hydrocarbon (PAH) pyrene in the marine deposit-feeding polychaete Nereis diversicolor. Identification of pyrene and primary metabolites was performed using high-pressure liquid chromatography (HPLC) with diode-array detection and fluorescence detection (HPLC/DAD/F) and an ion-trap mass spectrometer for positive identification of 1-hydroxypyrene glucuronide. Besides 1-hydroxypyrene and 1-hydroxypyrene glucuronide, the HPLC/F trace of tissue samples from pyrene-exposed worms showed three additional low-intensity peaks that may be related to pyrene metabolism based on similar excitation/emission wavelengths. The peaks were all too low in intensity to be positively identified. Of the total PAH in tissue, 1-hydroxypyrene glucuronide, 1-hydroxypyrene, and pyrene constituted 73%, 2%, and 25% respectively. Gut elimination of metabolic products is supported by the identification of 1-hydroxypyrene and 1-hydroxypyrene glucuronide in both gut fluid and defecation water. Being the only phase I metabolite of pyrene, 1-hydroxypyrene becomes a useful marker for PAH exposure, and it may serve as a valuable model compound for assessing species-specific PAH metabolic capabilities.
Effect of cortisol treatment and/or sublethal copper exposure on copper uptake and heat shock protein levels in common carp,Cyprinus carpio
Authors: De Boeck Gudrun , De Wachter Bart , Vlaeminck Andrea , Blust Ronny
Published: March 2010

This study compared the effects of increased endogenous cortisol levels and/or sublethal Cu exposure on Cu accumulation and stress protein levels (HSP70) in the freshwater common carp, Cyprinus carpio. Fish were exposed to either increased levels of endogenous cortisol (200 ng/ml) or sublethal Cu concentrations (1.9 μM, ∼20% of the acute 96-h median lethal concentration [LC50]) alone or were pretreated by elevating plasma cortisol levels prior to Cu exposure to evaluate whether interactions between both treatments occurred. Cortisol resulted in decreased Cu levels and a decreased Cu accumulation on a short-term basis (4 h). After 96 h of Cu exposure, cortisol pretreatment resulted in augmented Cu accumulation. Exposure to Cu increased HSP70 levels in gills, erythrocytes, and liver and decreased levels in brain and kidney. No clear relationship to Cu tissue levels was observed. Increased cortisol levels or treatment with cortisol before Cu exposure decreased the HSP70 response. We can conclude that cortisol elevation results in a lower HSP70 response and thus reduces the protection against cellular stress during metal accumulation. After an initial decrease in Cu accumulation, cortisol elevation eventually stimulates metal accumulation.
Effects of agricultural pesticides on the immune system of Rana pipiens and on its resistance to parasitic infection
Authors: Christin Marie-Soleil , Gendron Andrée D. , Brousseau Pauline , Ménard Lucie , Marcogliese David J. , Cyr Daniel , Ruby Sylvia , Fournier Michel
Published: March 2010

In the past 30 years, many amphibian species have suffered population declines throughout the world. Mass mortality have been frequently reported, and in several instances, infectious diseases appear to be the cause of death. The role that contaminants could play in these die-offs through immunotoxic effects has been poorly investigated. In this study, juvenile leopard frogs (Rana pipiens) were exposed for 21 d to a mixture of six pesticides (atrazine, metribuzin, aldicarb, endosulfane, lindane, and dieldrin) and subsequently challenged with a parasitic nematode, Rhabdias ranae. Exposure to the mixture at environmentally realistic concentrations significantly reduced lymphocyte proliferation. Three weeks after the end of the exposure, lymphocyte proliferation had recovered and was stimulated in frogs challenged with parasites with the exception of those previously exposed to the highest concentration. No pesticide effects on phagocytosis and splenocyte numbers were detectable at the end of the exposure period, but these two parameters were diminished 21 d after the infection challenge in frogs previously exposed to the highest levels of pesticides. In these animals, the prevalence of lung infection by R. ranae also tended to be higher. These results suggest that agricultural pesticides can alter the immune response of frogs and affect their ability to deal with parasitic infection.
Exposure of small mammals, in particular the wood mouse Apodemus sylvaticus, to pesticide seed treatments
Authors: Barber Ian , Tarrant Kenneth A. , Thompson Helen M.
Published: March 2010

Field exposure of small mammals to fungicide-treated wheat seed was investigated over three weeks following drilling on fields near York, United Kingdom. Seed consumption by small mammals trapped on and immediately adjacent to the drilled fields was quantified by measuring the amount of seed in the stomach. In addition, exposure to one seed-treatment, fluquinconazole, was quantified by measuring residues of the fungicide in the stomach, liver, and intestine. The wood mouse, Apodemus sylvaticus, was the dominant species caught on the fields and the only species found to have consumed measurable quantities of seed. Voles, Microtus agrestis and Clethrionomys glareolus, were caught in small numbers, almost exclusively in the field hedge, and showed no evidence of having consumed seed. Stomach-contents analysis revealed that more than 80% of animals trapped in the hedge adjacent to the field had consumed no wheat seed, whereas 98% had consumed less than 10% (by stomach volume). Ninety percent of animals trapped on the field had consumed seed, although 90% of these animals had less than 20% seed in the stomach. Residues of the fungicide in the stomach, intestine, and liver were lower than would be expected for the amount of seed consumed, possibly because of dehusking of the seeds by mice. The relevance of these findings when assessing exposure (and risk) posed by seed treatments to wild mammals is discussed.
Bioavailability of uranium and nickel to vegetation in a contaminated riparian ecosystem
Authors: Punshon Tracy , Gaines Karen F. , Bertsch Paul M. , Burger Joanna
Published: March 2010

The lower portion of Tims Branch (TB), a second-order stream system on the Savannah River site (SC, USA), receives influx of mixed waste-contaminated sediments from Steed Pond, a former settling basin for target processing wastes for over three decades. The magnitude and distribution of U, Ni, and other metals and the potential for trophic movement were studied to facilitate risk assessment and determine potential remedial action. Total and sequential extraction of TB soils demonstrated contaminant heterogeneity both spatially and between operationally defined fractions. Metal concentrations were elevated within riparian zone soils in contrast to stream sediments, suggesting off-site transport. Leaf tissue from TB contained an order of magnitude more Ni than tissue from reference sites. Leaves from streamside trees contained no U but elevated Ni up to 75.4 (±25) mg/kg dry weight (dry wt). Understory flora (Discanthelium sp. and Andropogon sp.) contained high concentrations of U associated with leaves up to 518 (±7.5) mg/kg dry weight U. The contrast in contaminant content and ratio of streamside and understory vegetation may result from resuspension of particulate U and Ni onto leaf surfaces and represents a potential pathway for trophic movement. The findings of this study have important ramifications for remediation of the ecosystem, suggesting that a strategy based on contaminant immobilization may be the most appropriate.
Accumulation of cadmium by durum wheat roots: Bases for citrate-mediated exceptions to the free ion model
Authors: Berkelaar Edward , Hale Beverley A.
Published: March 2010

The accumulation of Cd in durum wheat (Triticum turgidum) roots from hydroponic solutions, with the proportion of total Cd (8.9–445 nM Cd) as Cd2+ varied by the addition of citrate, was determined to test the free-ion model (FIM) of metal bioavailability for higher plants. Calcium, Mg, and K were also varied. Citrate enhanced root-Cd accumulation at higher Cd2+ concentrations but not lower relative to the same Cd2+ concentrations in solutions containing 0 mM citrate. Elevating Ca2+ and Mg2+ concentrations in the citrate solution to the same as those in control solutions alleviated some of the citrate-mediated enhancement but not all. Solutions containing 66% less Ca or Mg than control but the same Cd2+ concentration and no citrate also resulted in increased root Cd. Elevated K+ did not influence Cd accumulation. Regression relationships between root-Cd accumulation and total Cd in solution were similar for the control and pooled amended solutions, whereas they were different for root-Cd accumulation and solution Cd2+. These results contribute to the growing body of evidence that the FIM alone is likely insufficient to predict plant accumulation of metals from soils, although it may be a useful probe for the mechanistic bases of metal bioavailability.
Using a freshwater amphipod in situ bioassay as a sensitive tool to detect pesticide effects in the field
Authors: Schulz Ralf
Published: March 2010

In situ testing represents an alternative to conventional laboratory toxicity testing of field samples. Juvenile Paramelita nigroculus (Crustacea: Amphipoda) were exposed in situ in two rivers downstream of fruit orchard areas in the Western Cape, South Africa. Exposure took place during six time intervals (3–7 d), of which three represented the first rainfall-induced edge-of-field runoff events of the wet season, which was about two months after the last pesticide application. Survival rates were significantly reduced (35–70%) during runoff events 1 and 2 at both sites. No difference was observed from the respective no-runoff survival rate (>90%) during event 3. Peak levels of total insecticides (azinphosmethyl, chlorpyrifos, endosulfan, and prothiofos) in samples taken with water level-triggered samplers during the runoff events were between 0.03 and 0.26 μg/L in filtered water and between 305 and 870 μg/kg in suspended particles during runoff events 1 and 2 and only up to 0.01 μg/L and 101 μg/kg during event 3. Total suspended solids (TSS) varied between 400 and 700 mg/L during all three runoff events but never exceeded 65 mg/L during no-runoff time intervals. A laboratory experiment revealed that uncontaminated TSS levels of 1,500 mg/L during a 7-d exposure caused insignificant mortality (<2.5%) in P. nigroculus. No acute toxicity was observed in standard 48-h toxicity tests with juvenile Daphnia pulex using the filtered water samples taken during runoff and no-runoff conditions. It is concluded that the observed mortalities were caused by particle-associated pesticides and that the present amphipod in situ bioassay represents a sound and sensitive tool to detect runoff-related insecticide effects under field conditions.
Influence of desorption and contact time on sediment-water distribution of spiked polychlorinated biphenyls and polycyclic aromatic hydrocarbons: Relation with in situ distribution
Authors: ten Hulscher Theodora , Vrind Bea , van den Heuvel Henny , van Noort Paul , Govers Harrie
Published: March 2010

The long-term sediment—water distribution of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs), spiked to Lake Ketelmeer (The Netherlands) sediment, was studied using a gas-purge technique. Contact times varied from 2 to 1,461 d for the PCBs and from 5 to 100 d for the PAHs. Purge-induced desorption experiments lasted 300 to <4,000 h. The initial distribution coefficients that were observed during the first part of the experiment were close to literature values for distribution after short contact times. The distribution coefficients increased during the purge-induced desorption experiments. The final distribution coefficients that were observed during the last part of the experiment were one to two orders of magnitude higher than the initial values and were close to distribution coefficients reported earlier for in situ PCBs and PAHs present in a field-contaminated sediment for years to decades. The change in distribution coefficients during a gas-purge experiment may resemble the long-term change in a field sediment. Final distribution coefficients seem to be a more relevant measure for the distribution coefficients of hydrophobic organic chemicals in aged field sediments than values obtained after short contact times.
Air—water gas exchange of toxaphene in Lake Superior
Authors: Jantunen Liisa M. , Bidleman Terry F.
Published: March 2010

Parallel air and water samples were collected in Lake Superior during August 1996 and May 1997, to determine the levels and air—water exchange direction of toxaphene. Concentration of toxaphene in water did not vary across Lake Superior or between seasons (averaging 918 ± 218 pg/L) but atmospheric levels were lower in May (12 ± 4.6 pg/m3) than in August (28 ± 10 pg/m3). Two recalcitrant congeners, Parlar 26 and 50, also were determined. These congeners were enriched in the air samples, compared to a standard of technical toxaphene, but not in the water. Water—air fugacity ratios varied from 1.4 to 2.6 in August and 1.3 to 4.7 in May, implying volatilization of toxaphene from the lake. Estimated net fluxes ranged from 5.4 to 13 and 1.8 to 6.4 ng/m2d, respectively. The temperature dependence of toxaphene partial pressure (P) in air was log P/Pa = −3,291/Ta + 1.67, where Ta is air temperature. By using this relationship, the atmospheric levels of toxaphene, fugacity ratios, and net fluxes were estimated for the entire year. Fugacity ratios were highest in the winter and lowest in the summer; thus toxaphene was predicted to undergo net volatilization from the lake during all months. A net removal of approximately 220 kg/year by gas exchange was estimated.
Incomplete degradation of polycyclic aromatic hydrocarbons in soil inoculated with wood-rotting fungi and their effect on the indigenous soil bacteria
Authors: Andersson B. Erik , Lundstedt Staffan , Tornberg Karin , Schnürer Ylva , Öberg Lars G. , Mattiasson Bo
Published: March 2010

Soil artificially contaminated with fluorene, phenanthrene, pyrene, and benz[a]anthracene was inoculated with the wood-rotting fungi Pleurotus ostreatus and Antrodia vaillantii. During 12 weeks of incubation, polycyclic aromatic hydrocarbon (PAH) degradation and the formation of persistent degradation products were monitored by chemical analysis. In addition, the effect on the indigenous soil bacteria was studied by plate count techniques and by measuring the concentration of bacteria-specific phospholipid fatty acids (PLFAs). In both soils inoculated with fungi, the PAH degradation was enhanced compared to the control soil without fungi. The white-rot fungus P. ostreatus accelerated the degradation rate radically the first weeks, while the effect of the brown-rot fungus was more pronounced at later stages during the 12-week study. In a soil with no amendments, the final degradation result was similar to that in the soil with added fungi, although the degradation pattern for the individual PAHs was different. Furthermore, the degradation by P. ostreatus was accompanied by an accumulation of PAH metabolites, that is, 9-fluorenone, benz[a]anthracene-7,12-dione, and two compounds identified as 4-hydroxy-9-fluorenone and 4-oxapyrene-5-one, that was not seen in the other soils. The inoculation with the white-rot fungus also had a large negative effect on the indigenous soil bacteria. This could be an important drawback of using the white-rot fungus P. ostreatus in soil bioremediation since a sequential fungal—bacterial degradation probably is needed for a complete degradation of PAHs in soil. In the soil inoculated with A. vaillantii, on the other hand, no metabolites accumulated, and no negative effects were observed on the indigenous microorganisms.
Methyl parathion toxicity in vegetated and nonvegetated wetland mesocosms
Authors: Schulz Ralf , Moore Matt T. , Bennett Erin R. , Farris Jerry L. , Smith Sammie , Cooper Charles M.
Published: March 2010

Methyl parathion (MeP) was introduced into constructed wetlands for the purpose of assessing the influence of emergent vegetation on transport and toxicity of the pesticide. Two vegetated (90% cover, mainly Juncus effusus) and two nonvegetated wetland cells (each with a water body of 50 × 5.5 × 0.2 m) were each dosed with 6.5 m3 of water containing active ingredient of MeP at 6.6 mg/L associated with suspended soil at 400 mg/L to simulate a storm runoff event. Acute toxicity was assessed by sampling benthic macroinvertebrates at 5, 10, 20, and 40 m from the inlet before and 96 h after contamination and by in situ exposure of Chironomus tentans (Diptera) up to 24 h after contamination. Methyl parathion was detected throughout the nonvegetated wetland cells (70 μg/L at 20 m, 8 μg/L at 40 m), whereas the pesticide was not transported through the vegetated wetland cells (20 μg/L at 20 m, <0.1 μg/L at 40 m). A three-way analysis of variance using contamination (repeated measure variable), location, and vegetation indicated significant negative effects of contamination on various insect taxa, such as mayfly nymphs and caddisfly larvae. Seven out of the total of 15 species revealed a significant contamination × vegetation effect, with individuals in the vegetated wetlands being less affected. Four species showed a significant contamination × location effect, confirming a higher toxicity in the inlet area of the wetlands. A significant three-way interaction of contamination × vegetation × location was detected in Chironomus sp., which was most strongly affected at the inlet area of the nonvegetated wetland cells. The in situ bioassay employing C. tentans confirmed the positive effect of wetland vegetation on MeP toxicity. These results demonstrate the importance of vegetation for pesticide mitigation in constructed wetlands.
Life-history characteristics of Daphnia exposed to dissolved microcystin-LR and to the cyanobacterium Microcystis aeruginosa with and without microcystins
Authors: Lürling Miquel , van der Grinten Esther
Published: March 2010

In the current study, the role of microcystin(MC)-LR in inhibiting Daphnia growth was examined. Somatic growth, time to first reproduction, number of newborns, mortality, and population growth were measured in Daphnia fed mixtures of the cyanobacterium Microcystis aeruginosa (with and without microcystin) with a high quality green algal food (Scenedesmus obliquus) to avoid nutritional deficiency. Microcystin-LR-containing cells caused a dramatic reduction in growth and resulted in death of the animals, but the addition of purified toxin (microcystin-LR) had no effect on Daphnia growth. In contrast with the nutritional inadequacy hypothesis, growth on a mixture of Scenedesmus and the microcystin-free food was significantly reduced. This observation could not be explained from morphological characteristics of the strains that were uni- and bicellular. Clearance rates of Daphnia fed mixtures of Microcystis and Scenedesmus were significantly lower than rates of animals fed solely Scenedesmus. The results of an additional life-history experiment with different quantities of Scenedesmus could not reject the hypothesis that reduced feeding may be the causal factor in explaining reduced Daphnia growth on the food mixture with microcystin-free Microcystis. Thus, feeding inhibition should be considered in explaining the food quality of Microcystis and other cyanobacteria, as it could affect the total food intake and consequently Daphnia growth.
Toxicity of heavy metals using sperm cell and embryo toxicity bioassays withParacentrotus lividus(Echinodermata: Echinoidea): Comparisons with exposure concentrations in the Lagoon of Venice, Italy
Authors: Novelli Alessandra Arizzi , Losso Chiara , Ghetti Pier Francesco , Ghirardini Annamaria Volpi
Published: March 2010

Sperm cell and embryo toxicity tests using the Mediterranean sea urchin Paracentrotus lividus Lmk were performed to assess the toxicity of As3+, Cd2+, Cr3+, Ni2+, Pb2+, Cu2+, Zn2+, and Hg2+. The aim of this study was to improve information about the comparative sensitivity of sea urchin bioassays to the heavy metals, which are an important cause of contamination in the ecosystem of the Lagoon of Venice. Considering the data in mM/L, the order of toxicity is Hg2+ > Cu2+ > Zn2+ > As3+ ≥ Cr3+ ≥ Cd2+ ≥ Pb2+ ≥ Ni2+ for the sperm cell test and Hg2+ ≥ Pb2+ > Cu2+ > Zn2+ > Cd2+ > Ni2+ > As3+ ≥ Cr3+ for the embryo test. New toxicity data for metals expressed as median effective concentration (EC50) and no-observed-effect concentration (NOEC) are reported for the Mediterranean species. Accurate observations of embryotoxic effects at increasing metal concentrations were done, detecting some different behaviors in metal toxicity. Toxicity data compared with water column and pore-water concentrations recorded in the Lagoon of Venice (Italy) demonstrate the potential ability of bioassays using sea urchin to detect important contaminants in this ecosystem.
The relationships of biochemical endpoints to histopathology and population metrics in feral flatfish species collected near the municipal wastewater outfall of Orange County, California, USA
Authors: Roy Luke A. , Armstrong Jeffrey L. , Sakamoto Ken , Steinert Scott , Perkins Edwin , Lomax Daniel P. , Johnson Lyndal L. , Schlenk Daniel
Published: March 2010

In July 2000, 330 individuals of three flatfish species were collected from reference locations and nine sites surrounding the outfall of the Orange County (CA, USA) Sanitation District (OCSD) municipal wastewater discharge. Species included hornyhead turbot (Pleuronichthys verticalis), English sole (Pleuronectes vetulus), and bigmouth sole (Hippoglossina stomata). Livers of sampled animals were examined for the expression of vitellogenin (in males), cytochrome P450 1A (CYP1A), and DNA damage (comet assay). Biliary fluorescent aromatic compounds (FACs) were also measured. Comparisons with tissue and sediment contaminant residues, liver histopathology, and population estimates were assessed to determine whether relationships exist between levels of biological organization. The CYP1A results indicated exposure to planar aromatic hydrocarbons at one nearshore site. Regression analysis of all English sole CYP1A to total sediment polychlorinated biphenyls (PCBs) (r2 = 0.97; p < 0.05) indicated a significant correlation. Widespread exposure to estrogens was observed at all sites without correlation to the abundance of the three species examined. Fluorescent aromatic compounds demonstrated no correlation to CYP1A expression. Overall, histopathology and biochemical endpoints did not indicate significant adverse effects in fish at the OCSD outfall.
Variation, replication, and power analysis ofMyriophyllumspp. microcosm toxicity data
Authors: Hanson Mark L. , Sanderson Hans , Solomon Keith R.
Published: March 2010

Myriophyllum spp. have been proposed as a new standard laboratory aquatic macrophyte test species for the registration of pesticides. The main objectives of this investigation were to determine the power of Myriophyllum sibiricum and Myriophyllum spicatum toxicity data derived from an outdoor microcosm bioassay, to evaluate the variation of 10 different aquatic plant endpoints and to calculate the minimum detectable difference for these endpoints, to determine the replication required to detect ecologically significant changes from control for these endpoints, and to make recommendations for future field studies with Myriophyllum spp. Control data from four different studies that characterized haloacetic acid toxicity with Myriophyllum spp. for durations of three to six weeks during the summer of 1999 with five treatment levels (n = 3), including control, were examined. Endpoint coefficient of variation ranged, on average, from 6 to 28%. Node number and plant length endpoints were consistently the most statistically powerful for both plant species. It was possible to detect −30% change from control in both endpoints with high statistical power (β = 0.2, α = 0.05, n = 3). The range of minimum detectable differences was 40 to 60% for the other endpoints. Replication to detect a ≥25% change from control would require an n of 2 to 21, depending on the endpoint. Myriophyllum sibiricum had slightly lower coefficients of variation and thus required fewer replicates than M. spicatum to be statistically significantly different from control values. Variation within microcosm studies was not significantly different from that of controlled laboratory studies, implying that most of the variation observed in the field is inherent in the plants. Based on statistical sensitivity, ecological relevance, and toxicological sensitivity, we recommend using plant length and root endpoints as indicators of toxicity under field conditions.
Pyrethroid stimulation of ion transport across frog skin
Authors: Cassano Giuseppe , Bellantuono Vito , Ardizzone Concetta , Lippe Claudio
Published: March 2010

Pyrethroids are grouped into two classes (types I and II) because of the absence or presence of an α-cyano substituent and the production of a different intoxication syndrome in rodents. In this study, we investigated the effect of pyrethroids on the ion transport across frog skin (Rana esculenta). The short-circuit current value (estimate of ion transport) was increased by each of the eight pyrethroids tested, with the following order of potency: lambda-cyhalothrin > deltamethrin > alpha-cypermethrin = beta-cyfluthrin > bioallethrin > permethrin > bioresmethrin > phenothrin. The first four compounds are type II pyrethroids. Therefore, ion transport is stimulated more by type II pyrethroids than by type I. Experiments performed in the presence of amiloride support the conclusion that pyrethroids mainly increase Na+ absorption and to a lesser extent Cl− secretion. In these experiments, no systematic difference between type I and II pyrethroids was found. Finally, the stimulation by pyrethroids was inhibited by indomethacin and W7 (inhibitors of cyclooxygenases and the Ca2+/calmodulin system, respectively). These observations suggest that pyrethroids do not directly affect the epithelial Na+ channel (ENaC) but indirectly influence an intracellular event involved in ENaC modulation and linked to the Ca2+ signaling cascade.
Effects of the androgenic growth promoter 17-β-trenbolone on fecundity and reproductive endocrinology of the fathead minnow
Authors: Ankley Gerald T. , Jensen Kathleen M. , Makynen Elizabeth A. , Kahl Michael D. , Korte Joseph J. , Hornung Michael W. , Henry Tala R. , Denny Jeffrey S. , Leino Richard L. , Wilson Vickie S. , Cardon Mary C. , Hartig Phillip C. , Gray L. Earl
Published: March 2010

Trenbolone acetate is a synthetic steroid that is extensively used in the United States as a growth promoter in beef cattle. The acetate is administered to livestock via slow-release implants; some is converted by the animal to 17-β-trenbolone, a relatively potent androgen receptor agonist in mammalian systems. Recent studies indicate that excreted 17-β-trenbolone is comparatively stable in animal waste, suggesting the potential for exposure to aquatic animals via direct discharge, runoff, or both. However, little is known concerning the toxicity of trenbolone to fish. Our goal was to assess the effects of 17-β-trenbolone on reproductive endocrinology of the fathead minnow (Pimephales promelas). An in vitro competitive binding study with the fathead minnow androgen receptor demonstrated that 17-β-trenbolone had a higher affinity for the receptor than that of the endogenous ligand, testosterone. Male and female fish were exposed for 21 d to nominal (target) concentrations of 17-β-trenbolone ranging from 0.005 to 50 μg/L. Fecundity of the fish was significantly reduced by exposure to measured test concentrations ≥ 0.027 μg/ L. The 17-β-trenbolone was clearly androgenic in vivo at these concentrations, as evidenced by the de novo production in females of dorsal (nuptial) tubercles, structures normally present only on the heads of mature males. Plasma steroid (testosterone and β-estradiol) and vitellogenin concentrations in the females all were significantly reduced by exposure to 17-β-trenbolone. The 17-β-trenbolone also altered reproductive physiology of male fathead minnows, albeit at concentrations much higher than those producing effects in females. Males exposed to 17-β-trenbolone at 41 μg/L (measured) exhibited decreased plasma concentrations of 11-ketotestosterone and increased concentrations of β-estradiol and vitellogenin. Overall, our studies indicate that 17-β-trenbolone is a potent androgen and reproductive toxicant in fish. Given the widespread use of trenbolone acetate as a growth promoter, and relative stability of its metabolites in animal wastes, further studies are warranted to assess potential ecological risk.
Predicting the bioavailability of copper and zinc in soils: Modeling the partitioning of potentially bioavailable copper and zinc from soil solid to soil solution
Authors: Impellitteri Christopher A. , Saxe Jennifer K. , Cochran Melissa , Janssen Gijs M. C. M. , Allen Herbert E.
Published: March 2010

This research produced statistically based, semimechanistic models describing partitioning of Cu and Zn in 40 soils from the United States, Canada, the United Kingdom (UK), The Netherlands, and Chile with widely varying characteristics. Two different types of models were constructed, partitioning models and competitive adsorption models. Multiple linear regression (MLR) was employed to prioritize over 30 different soil characteristics. Multiple linear regression yielded equations predicting the partitioning of Cu and Zn. Equations were also created that estimated the potentially bioavailable fraction of Cu and/or Zn. Data from plant uptake studies (which are reported separately) governed the choice of a suitable chemical soil extraction that estimated bioavailable Cu (0.01 M HCl) and bioavailable Zn (0.01 M CaCl2). Soil pH (1:1 soil:deionized water [DI H2O]) and percent organic matter accounted for approximately 70% of the variability in Cu partitioning and 80% of the variability in bioavailable Cu in the 40 soils studied. For Zn, soil pH alone accounted for roughly 75% of the partitioning variability and 80% of the variability for the estimated bioavailable portion. The results presented here were used in conjunction with results from the plant uptake studies for the creation of models to assess the potential bioavailable metal associated with any given soil from a wide variety of locations.
Toxicity and pathogenicity of Metarhizium anisopliae var. acridum (Deuteromycotina, Hyphomycetes) and fipronil to the fringe-toed lizard Acanthodactylus dumerili (Squamata: Lacertidae)
Authors: Peveling Ralf , Demba Sy Amadou
Published: March 2010

Reptiles in arid and semiarid zones are frequently exposed to insecticides sprayed to control locusts and grasshoppers. We evaluated the toxicity and pathogenicity of new biological and chemical control agents to the fringe-toed lizard Acanthodactylus dumerili in Mauritania, West Africa. A mycoinsecticide based on spores of the entomopathogenic fungus Metarhizium anisopliae var. acridum (isolate IMI 330189, Green Muscle®) was tested at high challenge concentrations, using three exposure routes. Thirty-minute inhalation exposure to 3.9 × 108 viable conidia/L had no adverse effect. Locomotor activity, feeding activity, food consumption, body weight, and liver-to-body weight ratio were similar among treatments. Gross necropsy revealed no pulmonary lesions, hyphal mats, clumps of spores, or other abnormalities associated with fungal infections. Oral exposure to an oil-miscible flowable concentrate administered at approximately 107 viable conidia/g body weight had no effect on locomotor activity, food consumption, and body weight of survivors. However, two of the treated lizards died within one week of exposure. Feeding activity (sexes pooled) and relative liver mass of female survivors were significantly reduced. This was also observed in lizards treated with deactivated (nonviable) conidia, indicating an inherent toxicity of the formulation. Limited necropsy examination at four weeks posttreatment revealed that one lizard treated with viable spores had developed a pulmonary mycetoma that contained a clump of viable spores and fungal mycelium. The toxicity of mycotoxins was tested by feeding mycosed nymphs of desert locust Schistocerca gregaria to lizards. An average consumption of 231 mg (females) or 260 mg (males) nymphs/g body weight showed no adverse effect for any of the endpoints. No risk due to the pathogen is anticipated at recommended field application rates. The second agent tested was fipronil (Adonis®), a phenylpyrazole insecticide. A single dose of 30 μg fipronil/g body weight was administered via contaminated prey or stomach instillation. The percentage of dead or moribund lizards at four weeks posttreatment was 62.5% in animals fed contaminated prey and 42.0% in gavaged animals. In both tests, survivors showed significantly reduced feeding activity, food consumption, body weight, and organ-to-body-weight ratios (liver and/or fat body). The high toxicity of fipronil to lizards was not previously known, suggesting that follow-up studies (e.g., subacute dietary tests) are needed to provide adequate data for risk assessment.
Fish full life-cycle testing for the weak estrogen 4-tert-pentylphenol on medaka (Oryzias latipes)
Authors: Seki Masanori , Yokota Hirofumi , Matsubara Haruki , Maeda Masanobu , Tadokoro Hiroshi , Kobayashi Kunio
Published: March 2010

We studied the chronic effects of 4-tert-pentylphenol (4-PP) on reproductive status of medaka (Oryzias latipes) over two generations under continuous exposure, with the goal of verifying the applicability of the fish full life-cycle test (FFLC) for this weak estrogen with this species. The exposure of parental (F0) medaka to 4-PP was begun on embryos within 12 h after fertilization and continued for up to 101 d, with monitoring of embryological development, hatching, posthatch survival, growth, sexual differentiation, reproduction, and hepatic vitellogenin (VTG) levels under flow-through exposure to 4-PP at mean measured concentrations of 51.1, 100, 224, 402, and 931 μg/L. Eggs (F1) spawned from the F0 fish at 99, 100, and 101 d after hatch also were examined for hatchability, survival after hatching, growth, sexual differentiation, and hepatic VTG levels, until 61 d after hatch. In the FFLC with the F0 medaka, the lowest-observed-effect concentration (LOEC) of 4-PP for lethal and sublethal toxicity (as shown by growth inhibition) was 931 μg/L. The LOECs for estrogenic effects (as shown by abnormal sexual differentiation and VTG induction) were 224 and ≤51.1 μg/L, respectively, and the LOEC for reproductive impairment was 224 μg/L. Therefore, the effective concentrations of 4-PP for abnormal sexual differentiation and reproductive impairment were about four times lower than those for lethal and sublethal toxicity. In the F1 medaka, the LOECs for sublethal toxicity and estrogenic effects were 224 and ≤51.1 μg/L, respectively. This finding suggests that the continuous exposure to 4-PP over two generations induced these adverse effects at lower concentrations in the F1 generation than those in the F0 generation. Thus, 4-PP has estrogenic effects that reduce the reproductive potential of medaka. The results indicate that the FFLC with medaka is applicable to the evaluation of weak estrogens.
Reproductive and morphological effects of halogenated dimethyl bipyrroles on captive American kestrels (Falco sparverius)
Authors: Tittlemier Sheryl A. , Duffe Jason A. , Dallaire André D. , Bird David M. , Norstrom Ross J.
Published: March 2010

Sixty-four adult captive American kestrels (Falco sparverius) were exposed to a dietary source of halogenated dimethyl bipyrroles (HDBPs), a group of organohalogens proposed to have a natural origin. Adult kestrels were assigned to four treatment groups that were administered a different dose of HDBPs [high, 140 μg/(bird · d); medium, 4.3 μg/(bird · d); low, 0.13 μg/(bird · d); control, 0 μg/(bird · d)]. Exposure began prior to pairing and continued during breeding until approximately 28 d after hatching of the final eggs. Juvenile and adult kestrels accumulated HDBPs in carcass tissue, plasma, and liver. In addition, HDBPs were transferred to yolks during egg development. Low dietary absorption efficiencies (0.011–0.029) indicated that HDBPs were effectively cleared from kestrels either from increased elimination, metabolism, or a combination of the two processes. Reproductive and morphological endpoints examined for HDBP-induced changes included egg volume, egg mass, eggshell thickness, egg fertility, clutch size, liver and whole body mass, antebrachium, central retrice, tarsus, ninth primary, and wing cord lengths. Few statistically significant dose-dependent effects were observed. Hepatic tissue samples from selected individuals underwent histomorphological evaluation. Although the hepatic function was not evaluated specifically in these birds, no clinical signs suggestive of liver disease or gross hepatic anomalies were observed. Only minor histomorphological changes were detected in the hepatic tissue. The lack of serious effects suggests that HDBPs are not an acute reproductive threat to avian populations.