The Effects of Elevated Specific Conductivity on the Chronic Toxicity of Mining Influenced Streams Using Ceriodaphnia dubia

Salinization of freshwater ecosystems as a result of human activities has markedly increased in recent years. Much attention is currently directed at evaluating the effects of increased salinity on freshwater biota. In the Central Appalachian region of the eastern United States, specific conductance from alkaline discharges associated with mountain top mining practices has been implicated in macroinvertebrate community declines in streams receiving coal mining discharges. Whole effluent toxicity testing of receiving stream water was used to test the hypothesis that mine discharges are toxic to laboratory test organisms and further, that toxicity is related to ionic concentrations as indicated by conductivity. Chronic toxicity testing using Ceriodaphnia dubia was conducted by contract laboratories at 72 sites with a total of 129 tests over a 3.5 year period. The database was evaluated to determine the ionic composition of mine effluent dominated streams and whether discharge constituents were related to toxicity in C. dubia. As expected, sulfate was found to be the dominant anion in streams receiving mining discharges with bicarbonate variable and sometimes a substantial component of the dissolved solids. Overall, the temporal variability in conductance was low at each site which would indicate fairly stable water quality conditions. Results of the toxicity tests show no relationship between conductance and survival of C. dubia in the mining influenced streams with the traditional toxicity test endpoints. However, consideration of the entire dataset revealed a significant inverse relationship between conductivity and neonate production. While conductivity explained very little of the high variability in the offspring production (r² = 0.1304), the average numbers of offspring were consistently less than 20 neonates at the highest conductivities.     

Acute toxicity of a household bleach,sodium hypochlorite,to a whirligig beetle Orectogyrus alluaudi Régimbart, 1889 (Coleoptera: Gyrinidae)

Acute response of Orectogyrus alluaudi Régimbart, 1889 to sodium hypochlorite was reported after a 48-h acute toxicity test in an imitated field condition. O. alluaudi belongs to the water beetle family Gyrinidae (whirligig beetles) which includes more than 700 species. The test organisms were exposed to various concentrations of sodium hypochlorite ranging from 10 to 160 mg/l along with the control, and median lethal concentration (LC₅₀) values at 24 and 48 h of exposure were assessed. Mortality increased with the concentration of exposure. The 24 and 48 h LC₅₀ values estimated for sodium hypochlorite were 87.30 (73.21–107.06) and 72.32 (62.24–84.53) mg/l, respectively. A significant mortality (P < 0.001) was observed at 40, 80 and 160 mg/l of sodium hypochlorite when compared with the control. Addition of sodium hypochlorite altered the alkalinity and pH of the test water. Behavioural responses such as agitation and disorientation were also observed. The finding showed that indiscriminate use of the household bleach would have serious impact on the bionomics of this species.     

Toxicity of plant essential oils to different life stages of the poultry red mite,Dermanyssus gallinae,and non‐target invertebrates

Seven essential oils with potential as acaricides for use against the poultry red mite, Dermanyssus gallinae (De Geer) (Acari: Dermanyssidae), were selected for study. These products (essential oils of manuka, cade, pennyroyal, thyme, garlic, clove bud and cinnamon bark) were deployed against different life stages of D. gallinae in laboratory tests at the (lethal concentration) LC₅₀ level for adult mites. For all essential oils tested, toxicity to D. gallinae juveniles was as high as toxicity to adults, if not higher. However, at the LC₅₀ level determined for adults, some oils were ineffective in preventing hatching of D. gallinae eggs. The essential oils were also tested under laboratory conditions at their LC₉₀ levels for D. gallinae adults on two model non‐target species, the brine shrimp, Artemia salina (L.), and the mealworm beetle, Tenebrio molitor (L.). Results showed that not all essential oils were as toxic to A. salina and T. molitor as they were to D. gallinae, suggesting that it may be possible to select certain oils for development as acaricides against D. gallinae that would have minimal impact on non‐target organisms. However, the level of toxicity to A. salina and T. molitor was not consistent across the selected essential oils.     

Acute toxicity tests on three species of the genus Lecane (Rotifera: Monogononta)

Three rotifer species, Lecane hamata L. luna, and L. quadridentata, were submitted to acute toxicity tests to compare their susceptibility to 11 toxicants. In acute tests with 48-h exposure of neonates of less than 24 h old, copper was most toxic with LC₅₀ values in the range of 0.06–0.33 mg l^–1, while acetone was the least toxic with LC₅₀ values in the range of 5000–7000 mg l^–1. Differences in LC₅₀ value of up to 22-fold were found in the susceptibility to lead between the three species. These data indicate large differences in toxicity among members of the same genus, and point out that it is necessary to submit several species to toxicity tests in order to assess the potential effects of toxicants to rotifers. The commonly used Brachionus calyciflorus cannot be considered representative of all freshwater rotifers in this respect.     

Acute toxic impacts of three heavy metals (copper,zinc, and cadmium) on <Emphasis Type="Italic">Diaphanosoma brachyurum</Emphasis> (Cladocera: Sididae)

Diaphanosoma brachyurum (Cladocera: Sididae) is a common limnetic species in summer-temperate and tropical water bodies. Few studies have investigated the sensitivity of D. brachyurum to toxic chemicals despite this species often being dominant in natural lakes and ponds. We performed acute toxicity tests of three heavy metals, copper (Cu), zinc (Zn), and cadmium (Cd), to D. brachyurum. For D. brachyurum, the lethal concentration (LC)₅₀ values of Cu (24-h LC₅₀ = 16.4 μg/L, 48-h LC₅₀ = 10.4 μg/L) and Zn (24-h LC₅₀ = 253.4 μg/L, 48-h LC₅₀ = 174.1 μg/L) were lower than those for D. magna, one of the most used test organisms for toxic chemicals. On the other hand, for D. brachyurum the 24-h LC₅₀ of Cd (166.4 μg/L) was much greater than that for D. magna, and the 48-h LC₅₀ of Cd (69.8 μg/L) was comparable. Our results indicate that D. brachyurum may be more strongly influenced by Zn and Cu than is D. magna. It is likely that the summer plankton community in which Diaphanosoma species is dominant is more sensitive to heavy metals than a community in which Daphnia species are dominant.     

Acute Toxicity Tests with Cadmium,Lead, Sodium Dodecyl Sulfate,and Bacillus thuringiensis on a Temporary Pond Ostracod

A complete assessment of effects of pollutants in the environment requires the use of a wide assemblage of test organisms. Crustaceans have been widely used in aquatic environments, but within this group, ostracods have been overlooked, even though they are one of the commonest groups of animals in temporary waters. Within this framework, static acute toxicity bioassays were conducted with heavy metals Cd and Pb, the surfactant SDS and spores of the bacteria Bacillus thuringiensis var. israeliensis using adult parthenogenetic females of the temporary pond ostracod Heterocypris bosniaca. Experiments were run at 20 °C and in a 12 by 12 h photoperiod. The toxicity tests results are expressed as LC₅₀ and EC₅₀ at 48 h and 96 h using probit analysis. The sensitivity of H. bosniaca at 48 h decreased in the following order Cd > Pb > SDS > Bti, while Pb and SDS exchanged their positions at 96 h. Comparison of the LC₅₀ values for this species with information available in the literature reveals that it is generally more resistant than other crustaceans. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Influence of Conductivity Dissipation on Benthic Macroinvertebrates in the North Fork Holston River,Virginia Downstream of a Point Source Brine Discharge during Severe Low-Flow Conditions

The North Fork Holston River (NFHR) was examined in fall 2005 to determine the potential impact of a brine discharge on benthic macroinvertebrates. Conductivity of the discharge ranged from 5900 to 10,930 μ S/cm with a highest measurement of 18,000 μ S/cm. During normal flow, conductivity dissipates rapidly downstream of the discharge; however, low-flow conditions in 2005 hindered dissipation. Benthic macroinvertebrate surveys determined statistically significant differences (p = .05) in all metrices between sites excluding taxa richness. Hydropsychid caddisflies were the predominant taxa at the first two sites below the brine discharge, accounting for 74.3 and 68.8% of the organisms collected. Therefore, Ephemeroptera-Plecoptera-Trichoptera (EPT) abundance minus Hydropsychidae [EPT-H] was the most predictive parameter measured. When hydropsychids were removed from statistical analyses, mean EPT abundance was highest at upstream reference sites 1 and 2 (256 and 297, respectively) and reduced at all downstream sites, ranging from 24 to 52 EPT organisms. Virginia Stream Condition Index (SCI) scores indicated impairment downstream of the discharge with scores of 46.9, 41.8, and 55.8, well below the impairment threshold of 61. These results suggest subchronic, intermittent toxicity occurs under low-flow and may contribute to altered benthic macroinvertebrate assemblages downstream of the brine discharge for approximately 26 miles.     

Acute toxicity of tributyltin to encapsulated embryos of a marine gastropod

The marine gastropod Buccinanops globulosus is known to have high imposex incidence in areas moderately polluted by tributyltin (TBT). Acute toxicity was previously studied in adults but no information is known about embryonic intracapsular development. To estimate the potential effects of organotin pollution on the progeny of B. globulosus, acute toxicity tests were conducted on encapsulated and excapsulated pre-hatching embryos. The lethal median concentration estimated for 96?h (LC₅₀ 96?h) in B. globulosus excapsulated embryos was 196.70?µg?TBTCl?L^?1, while in encapsulated embryos it was 2951.28?µg?TBTCl?L^?1. The LC₅₀ 96?h was 15-fold higher for encapsulated embryos compared to excapsulated embryos, denoting egg capsule protection against pollutants from the external environment. Our results show that TBT pollution can have significant effects in molluscs other than the chronic effect of imposex.     

The effects of salinity on acute and chronic nickel toxicity and bioaccumulation in two euryhaline crustaceans: Litopenaeus vannamei and Excirolana armata

We investigated the influence of salinity (5 ppt versus 25 ppt) on acute (96-h LC₅₀) and chronic toxicity (15–30 day LC₅₀) of Ni in two euryhaline crustaceans, the shrimp (Litopenaeus vannamei) and the isopod (Excirolana armata). 96-h LC50 values were 41 μmol L⁻¹ and 362 μmol L⁻¹ for L. vannamei and 278 μmol L⁻¹ and > 1000 μmol L⁻¹ for E. armata at 5 ppt and 25 ppt, respectively. Speciation analysis demonstrated that complexation with anions such as SO₄²⁻, HCO₃⁻ and Cl⁻ at 25 ppt had a negligible effect on reducing the free Ni²⁺ ion component in comparison to 5 ppt. The salinity-dependent differences in acute Ni toxicity could not be explained by differences in Ni bioaccumulation. Therefore, differences in physiology of the organisms at the two salinities may be the most likely factor contributing to differences in acute Ni toxicity. Chronic LC₅₀ values (2.7–23.2 μmol L⁻¹) were similar in the two species, but salinity had no significant effect, indicating that water chemistry and osmoregulatory strategy do not influence chronic toxicity. However chronic (15-day) mortality in both species could be predicted by acute (96-h) Ni bioaccumulation patterns.     

Chemical Constituents and Insecticidal Activities of Ajania fruticulosa Essential Oil

The insecticidal activity and chemical constituents of the essential oil from Ajania fruticulosa were investigated. Twelve constituents representing 91.0% of the essential oil were identified, and the main constituents were 1,8‐cineole ( 41.40% ), (+)‐camphor ( 32.10% ), and myrtenol (8.15%). The essential oil exhibited contact toxicity against Tribolium castaneum and Liposcelis bostrychophila adults with LD₅₀ values of 105.67 μg/adult and 89.85 μg/cm², respectively. The essential oil also showed fumigant toxicity against two species of insect with LC₅₀ values of 11.52 and 0.65 mg/l, respectively. 1,8‐Cineole exhibited excellent fumigant toxicity (LC₅₀ = 5.47 mg/l) against T. castaneum. (+)‐Camphor showed obvious fumigant toxicity (LC₅₀ = 0.43 mg/l) against L. bostrychophila. Myrtenol showed contact toxicity (LD₅₀ = 29.40 μg/cm²) and fumigant toxicity (LC₅₀ = 0.50 mg/l) against L. bostrychophila. 1,8‐Cineole and (+)‐camphor showed strong insecticidal activity to some important insects, and they are main constituents of A. fruticulosa essential oil. The two compounds may be related to insecticidal activity of A. fruticulosa essential oil against T. castaneum and L. bostrychophila.     

Implementation of a multiple biomonitoring approach to evaluate the potential for impact from an industrial discharge

Over a 2-year period, an industrial discharger implemented a program to determine if there was a potential for in-stream impact from its discharge, and, if necessary, to eliminate that potential. Six basic study designs were used. These included: (1) ambient toxicity tests using indicator organisms; (2) in-stream waste concentration (IWC) chronic testing using indicator organisms; (3) on-site flow-through toxicity testing using indicator and resident species with receiving stream water as the diluent; (4) in situ acute toxicity studies using indicator and resident species; (5) biological surveys of the receiving stream; and (6) artificial stream studies. The outcome of the studies resulted in conclusive data on which to base the design of a diffuser to dilute the effluent 1:20. This concentration was well below the lowest acute no-observed-effect concentration (10% effluent) determined using sensitive resident test species. In this manner, impact from the effluent on the James River had been reduced so that even the most sensitive resident species were protected. As a result of the study, the facility's permit was modified so that toxicity tests were made only on effluent diluted with receiving stream water to represent dilution at 1Q10 rather than 100 percent effluent. Follow-up studies have concentrated on a series of toxicity tests which were designed to identify the toxicants in the final effluent.     

Relative Sensitivity Distribution of Freshwater Planktonic Crustaceans to Trace Metals

Cladocerans and copepods are common inhabitants of ponds and lakes, but assessments of the toxic effects of chemicals on aquatic organisms are often based mainly on toxicity data for cladocerans of the genus Daphnia. The paucity of toxicity data for copepods and other species of cladocerans raised the question whether toxicity data derived primarily from daphniids can be extrapolated to protect other planktonic organisms. In this study, we address this question by systematically comparing between the sensitivities of cladocerans and copepods to the metals Cd, Cu, Pb, Ni, and Zn using the species sensitivity distributions. Our results indicate that cladocerans are consistently more sensitive than copepods to Cd and Cu. Most importantly, sensitivities of D. magna, D. pulex, and Ceriodaphnia dubia, the three most commonly tested cladocerans, to these metals are higher than those of most copepod species and fall within the range of those exhibited by other cladocerans. C. dubia, a cladoceran with relatively small body size, is more sensitive to all metals than most other cladoceran species. Our results imply that water quality criteria of trace metals derived from datasets dominated by Daphnia are likely also protective to copepods and most other cladocerans.     

Cultivation of the heart urchin Echinocardium cordatum and validation of its use in marine toxicity testing for environmental risk assessment

To study environmental risk assessment, echinoderms provide a useful model for ecotoxicological testing. However, limited knowledge of the life history of field collected heart urchins is a problem and the use of cultured urchins has been investigated here. The present study describes a culture method for the heart urchin Echinocardium cordatum under controlled laboratory conditions, providing organisms with a low biological variation. Based on our optimized growth protocol both larvae and juveniles have a growth rate comparable to E. cordatum in the wild. The toxicological response of cultured and field-collected E. cordatum was compared in standard saltwater toxicity bioassays. Using ammonium chloride as a water-soluble reference toxicant, mean 96 h LC₅₀ values for cultured heart urchins versus field collected animals were 37.4 ± 7.6 mg NH₄+/l (n = 5) versus 22.5 ± 4.9 mg NH₄+/l (n = 19), respectively. Additional toxicity experiments with tributyl tin (TBT) spiked sediments revealed 14d LC₅₀ values of 1,242 (95% confidence interval 986–1,564) and 964 (95% confidence interval 843–1,102) µg Sn/kg dw respectively in cultured and field collected E. cordatum. From this it was concluded that cultured heart urchins are less sensitive to TBT than field collected E. cordatum. Furthermore in whole sediment toxicity tests, survival of cultured sea urchins was higher or at least similar to that of field collected E. cordatum. The increased sensitivity of field urchins compared to cultured urchins in various toxicity tests may be due to multiple environmental stressors reducing their overall performance. Overall it was demonstrated that the use of cultured E. cordatum provides a significant advance for urchin-based bioassays for marine environmental toxicity testing, resulting in a more homogeneous, vital population with experimental data displaying reduced variability.     

Development of a bioassay reagent usingPhotobacterium phosphoreum as a test for the detection of aquatic toxicants

Lyophilized cells ofPhotobacterium phosphoreum, rehydrated in 2% (w/v) NaCl in 0.022M KH₂PO₄ at pH 7.0, were used for developing an assay to test the acute toxicity of organic and inorganic compounds. The standardized assay gave good reproducibility of results with 11 organic and four inorganic compounds. Results were compared with reported data obtained with other test organisms and are within their sensitivity ranges. Environmental screening of wastes from oil and petrochemical industries is discussed.     

Influences of water chemistry on the acute toxicity of lead to Pimephales promelas and Ceriodaphnia dubia

The acute toxicity of lead (Pb) was examined for fathead minnows (Pimephales promelas; 96-h) and daphnids (Ceriodaphnia dubia; 48-h) in waters modified for hardness (as CaSO₄), dissolved organic carbon (DOC; as Aldrich humic acid) and alkalinity (as NaHCO₃) for parameterization of an acute freshwater biotic ligand model (BLM). Additionally, acute (96-h) and chronic (30-d) bioassays were performed for P. promelas to more clearly define the influence of pH (5.5–8.3) on Pb toxicity as modified by addition of HCl or NaOH using an automated titration system. Results indicate that Ca²⁺ is protective against acute Pb toxicity to P. promelas but not C. dubia. Strong protection was afforded by DOC and NaHCO₃ against acute Pb toxicity to P. promelas, whereas milder protection was observed for C. dubia with both parameters. Dissolved Pb LC50s from the P. promelas pH bioassays revealed a complex effect of pH on Pb toxicity, likely explained in part by Pb speciation and the competitive interaction of H⁺ with ionic Pb²⁺. Chronic pH bioassays also demonstrated that 30-d growth is not impaired in fathead minnows at relevant Pb concentrations. The findings reported herein suggest that development of separate BLMs for P. promelas and C. dubia should be considered.     

Acute toxicity and adverse effects of aqueous and ethanol extracts of Parkia biglobosa pods on biochemical parameters of Clarias gariepinus

The acute toxicity of the aqueous and ethanol extracts of Parkia biglobosa pods against Clarias gariepinus was investigated under laboratory conditions. Agitated behaviours and respiratory distress were also observed during the exposure period. The adverse effects on biochemical parameters were assessed using semi-static bioassays for 28 days. The ethanol extract of P. biglobosa pods was found to be more acutely toxic with a 96 h LC₅₀ value of 13.96 mg l^?1 than the aqueous extracts, with a 96 h LC₅₀ value of 19.95 mg l^?1 against C. gariepinus. Both extracts induced agitated behaviours and respiratory distress in exposed organisms. The activities of superoxide dismutase (SOD), catalase (CAT) and the concentration of malondialdehyde (MDA) were significantly lower (p < 0.05) in groups of organisms exposed to extracts of P. biglobosa when compared with the control group after 14 days. The activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were also significantly (p < 0.05) lower compared with activities of the enzymes in the control group after 28 days. The current study has shown that the introduction of P. biglobosa pods into aquatic ecosystems is acutely toxic to fish and would possibly be to other non-target aquatic organisms especially invertebrates.     

Chemical Characterization and Insecticidal Properties of Essential Oils from Different Wild Populations of Mentha suaveolens subsp. timija (Briq.) Harley from Morocco

The present study is the first investigation of the volatile‐oil variability and insecticidal properties of the endemic Moroccan mint Mentha suaveolens subsp. timija (mint timija). The yield of essential oils (EOs) obtained from different wild mint timija populations ranged from 0.20±0.02 to 1.17±0.25% (v/w). GC/MS Analysis revealed the presence of 44 oil constituents, comprising 97.3–99.9% of the total oil compositions. The main constituents were found to be menthone (1.2–62.6%), pulegone (0.8–26.6%), cis‐piperitone epoxide (2.9–25.5%), piperitone (0.3–35.5%), trans‐piperitone epoxide (8.1–15.7%), piperitenone (0.2–9.6%), piperitenone oxide (0.5–28.6%), (E)‐caryophyllene (1.5–11.0%), germacrene D (1.0–15.7%), isomenthone (0.3–7.7%), and borneol (0.2–7.3%). Hierarchical‐cluster analysis allowed the classification of the EOs of the different mint timija populations into four main groups according to the contents of their major components. This variability within the species showed to be linked to the altitude variation of the mint timija growing sites. The results of the insecticidal tests showed that all samples exhibited interesting activity against adults of Tribolium castaneum, but with different degrees. The highest toxicity was observed for the EOs belonging to Group IV, which were rich in menthone and pulegone, with LC₅₀ and LC₉₀ values of 19.0–23.4 and 54.9–58.0 μl/l air in the fumigation assay and LC₅₀ and LC₉₀ values of 0.17–0.18 and 0.40–0.52 μl/cm² in the contact assay.     

Neck organ ofArtemia salina nauplii

Summary The ability of brine shrimp nauplii (Artemia salina L.) to exist in a wide range of salinities results from an active excretion of sodium ions from the body into the external environment. Localization of NaCl in the neck organ suggests that this is the site of salt secretion. Ultrastructural studies support this view, the structure of the neck organ being characteristic of salt glands in the adult brine shrimp and other organisms.This is the first article in a series; the second article appeared already in Vol. 79 (Hootmanet al.).This work was supported by NSF grant 30-262-1547 and AEC grant RLO 2227-T13-1. The authors wish to express their gratitude to Prof. D. Eugene Copeland for use of the photograph of the adultArtemia with AgNO₃-stained branchial metepipodites (Fig. 2A).     

Toxicity of Acaricides to the Bulb Mite Rhizoglyphus Echinopus (Acari: Acaridae)

Using a continuous exposure technique, the toxicity of 35 compounds to the bulb mite, Rhizoglyphus echinopus (Fumouze and Robin) was examined after 48 h. Sixteen acaricides yielded an LC₅₀ of <1.0 mg cm². The highest toxicity was exhibited by cyclodiene GABA antagonists (dieldrin, endrin and aldrin), some organophosphate (chlorpyrifos, diazinon and azinphosethyl) and carbamate (carbofuran) anticholinesterases and a thiazolidine flubenzimine. Oxythioquinox, fenazaflor, fenazaquin and amitraz were less toxic than the cyclodienes, organophosphates and carbamates. The sodium channel agonists (DDT and pyrethroids) and several specific acaricides with other modes of action were inactive (LC₅₀ >11.0 mg cm^-2).     

Sublethal Toxicity Testing of Canadian Metal Mining Effluents: National Trends and Site-Specific Uses

As part of the Canadian Environmental Effects Monitoring program under the National Metal Mining Effluent Regulation, there is a requirement to conduct sublethal toxicity tests twice per year for the first three years. These first three years (2003 to 2005) were considered a period of initial monitoring and resulted in test endpoints for each of the required standardized methods on a fish, an aquatic plant, an invertebrate, and an algal species. On a national level (based on 1648 valid results), the test from most to least sensitive was: the inhibition of reproduction with Ceriodaphnia dubia, the growth inhibition (frond number) with Lemna minor, the inhibition of cell yield with Pseudokirchneriella subcapitata, the growth inhibition (dry weight) with Lemna minor, the growth inhibition of fathead minnows, and the effect on embryo viability with rainbow trout. This sensitivity ranking changed when tests were further evaluated on a geographical region and mine-type basis (e.g., base metal, precious metal, uranium, iron ore). Site-specific examples show how sublethal toxicity data are being used to track changes in effluent quality, choosing a final discharge point, monitoring multiple discharges to the same watercourse, and to identify study design weaknesses by comparing laboratory results to field survey conclusions.