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At least 199 records · Page 11Linked to original sources
USGS1996

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

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.

Environmental Toxicology and Chemistry↗
USGS2023

Review and development of best practices for toxicity tests with dreissenid mussels

Since their introduction to North America in the 1980s, research to develop effective control tools for invasive mussels ( Dreissena polymorpha and D. rostriformis bugensis ) has been ongoing across various research institutions using a range of testing methods. Inconsistencies in experimental methods and reporting present challenges for comparing data, repeating experiments, and applying results. The Invasive Mussel Collaborative established the Toxicity Testing Work Group (TTWG) in 2019 to identify “best practices” and guide development of a standard framework for dreissenid mussel toxicity testing protocols. We reviewed the literature related to laboratory-based dreissenid mussel toxicity tests and determined the degree to which standard guidelines have been used and their applicability to dreissenid mussel testing. We extracted detailed methodology from 99 studies from the peer-reviewed and gray literature and conducted a separate analysis for studies using presettlement and postsettlement mussels. We identified specific components of methods and approaches that could be refined or standardized for dreissenid mussels. These components included species identification, collection methods, size/age class distinction, maintenance practices, testing criteria, sample size, response measures, reporting parameters, exposure methods, and mortality criteria. We consulted experts in the field of aquatic toxicology and dreissenid mussel biology on our proposed. The final recommendations contained in the present review are based on published standard guidelines, methods reported in the published and gray literature, and the expertise of TTWG members and an external panel. In addition, our review identifies research needs for dreissenid mussel testing including improved methods for early–life stage testing, comparative data on life stages and between dreissenid mussel species, inclusion of a reference toxicant, and additional testing of nontarget species (i.e., other aquatic organisms). Environ Toxicol Chem 2023;42:1649–1666. © 2023 His Majesty the King in Right of Canada. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. Reproduced with the permission of the Minister of Environment and Climate Change Canada. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Environmental Toxicology and Chemistry↗
USGS2016

An evaluation of inorganic toxicity reference values for use in assessing hazards to American robins ( Turdus migratorius )

When performing screening-level and baseline risk assessments, assessors usually compare estimated exposures of wildlife receptor species with toxicity reference values (TRVs). We modeled the exposure of American robins ( Turdus migratorius ) to 10 elements (As, Cd, Cr, Cu, Hg, Mn, Pb, Se, Zn, and V) in spring and early summer, a time when earthworms are the preferred prey. We calculated soil benchmarks associated with possible toxic effects to these robins from 6 sets of published TRVs. Several of the resulting soil screening-level benchmarks were inconsistent with each other and less than soil background concentrations. Accordingly, we examined the derivations of the TRVs as a possible source of error. In the case of V, a particularly toxic chemical compound (ammonium vanadate) containing V, not normally present in soil, had been used to estimate a TRV. In the cases of Zn and Cu, use of uncertainty values of 10 in estimating TRVs led to implausibly low soil screening values. In the case of Pb, a TRV was calculated from studies demonstrating reductions in egg production in Japanese quail ( Coturnix coturnix japonica ) exposed to Pb concentrations well below than those causing toxic effects in other species of birds. The results on quail, which were replicated in additional trials, are probably not applicable to other, unrelated species, although we acknowledge that only a small fraction of all species of birds has been tested. These examples underscore the importance of understanding the derivation and relevance of TRVs before selecting them for use in screening or in ecological risk assessment.

Integrated Environmental Assessment and Management↗
USGS1994

Identification of tire leachate toxicants and a risk assessment of water quality effects using tire reefs in canals

Cover is an important component of aquatic habitat and fisheries management. Fisheries biologists often try to improve habitats through the addition of natural and artificial material to improve cover diversity and complexity. Habitat-improvement programs range from submerging used Christmas trees to more complex programs using sophisticated artificial habitat modules. Used automobile tires have been employed in the large scale construction of reefs and fish attractors in marine environments (D'Itri 1985) and to a lesser extent in freshwater (Johnson and Stein 1979) and have been recognized as a durable, inexpensive and long-lasting material which benefits fishery communities. Recent studies by the U.S. Bureau of Reclamation (Mueller and Liston 1991) have quantified the importance of tire reeds to enhancing freshwater canal fisheries in the southwestern United States. These studies have demonstrated that fisheries and aquatic macroinvertebrates are attracted to these structures, increasing species diversity, densities and biomass where reefs are places in canals. Potential benefits to fishermen are great in the form of recreational fishing. However, the use of tire reefs in aquatic environments which have relatively small volumes compared to marine or reservoir environments has raised water quality concerns. Effects of tires on water quality have not typically been studied in the part because of the obvious presence of fishes and other aquatic organisms that make use of tire reefs; the implication being that tires are intert and non-toxic. Little information on effects of tires on water quality is contained in the literature. Stone et al. (1975) demonstrated that tire exposure had no detrimental effects on two species of marine fish while results of Kellough's (1991) freshwater tests were inconclusive, but suggested that some factor in tire leachate was toxic to rainbow trout ( Oncorhynchus mykiss ). Nozaka et al. (1973) found no harmful substances leached from tire material soaked in fresh water. Because there are few data on toxicity associated with tires, this became the focus of our study. Toxicity Identification Evaluation (TUE) procedures developed by the EPA (1991) were used to evaluate water quality impacted by tires.

Bulletin of Environmental Contamination and Toxico↗
USGS1996

Toxicity of seleno-l-methionine, seleno-dl-methionine, high selenium wheat, and selenized yeast to mallard ducklings

The toxicity of four chemical forms of selenium (seleno-L-methionine, seleno-DL-methionine, selenized yeast, and high selenium wheat) was compared in day-old mallard ducklings ( Anas platyrhynchos ). In the first experiment, in which the basal diet was 75% wheat, survival after 2 weeks was lower for ducklings fed 30 μg/g selenium as seleno-L-methionine (36%) than for ducklings fed 30 μg/g selenium as seleno-DL-methionine (100%) or 30 μg/g selenium from high selenium yeast (88%). The concentration of selenium at 2 weeks in the livers of survivors was similar for ducklings fed 15 μg/g selenium as seleno-DL-methionine (12 μg/g, wet weight), seleno-L-methionine (11 μg/g), and high selenium wheat (11 μg/g), but was lower when the selenium came from selenized yeast (6.2 μg/g). When fed 30 μg/g selenium from the various sources, the selenium concentrations in liver were 20 μg/g for seleno-DL-methionine, 19 μg/g for seleno-L-methionine, and 9.9 μg/g for selenized yeast. In a second experiment, in which the basal diet was a commercial duck feed, survival after 2 weeks was 100% in ducklings fed 30 μg/g selenium as seleno-DL-methionine, seleno-L-methionine, or selenized yeast. Selenium concentrations in liver were similar for ducklings fed the 30-μg/g selenium diets as the DL or L forms of selenomethionine (27 and 25 μg/g), but lower for ducklings fed selenized yeast (13 μg/g). The greater toxicity of the L form of selenomethionine was probably related to the palatability or nutritional nature of the wheat-based diet used in experiment 1, but the exact reason for the difference between the DL and L forms is unknown. Biologically incorporated selenium, derived from high selenium wheat, was no more toxic than selenium derived from the two purified forms of selenomethionine, and the selenium in selenized yeast was not as toxic as that in the two forms of selenomethionine.

Archives of Environmental Contamination and Toxico↗
USGS1995

Sediment toxicity in Savannah Harbor

Savannah Harbor, located near the mouth of the Savannah River, Georgia and South Carolina, is impacted by industrial and municipal effluents. Potential release of contaminants stored in harbor sediments through dredging and shipping operations requires that contaminated areas be identified for proper management of the system and protection of wildlife resources. During 1991, Hyalella azteca were exposed in 10-d static-renewal toxicity tests to pore-water and solid-phase sediment samples collected from 26 sites within Savannah Harbor. Pore-water toxicity was more pronounced than that for solidphase sediment. Toxicity and reduced leaf consumption demonstrated impaired sediment quality at specific sites within Savannah Harbor and Back River. Factors responsible for the decreased sediment quality were ammonia, alkalinity, and metal concentrations (cadmium, chromium, lead, molybdenum, and nickel). Elevated concentrations of metals and toxicities in Back River sediments indicated impacts from adjacent dredge-spoil areas.

Georgia↗
USGS1985

Acute oral toxicity and repellency of 933 chemicals to house and deer mice

Five individual bioassay repellency or toxicity variables were estimated or determined for deer mice ( Peromyscus maniculatus ) and house mice ( Mus musculus ) under laboratory conditions. ALD's (Approximate Lethal Doses) or LD 50 's of 230 chemicals to deer mice are presented, as are food reduction (FR) values (3-day feeding test as a 2.0% treatment rate) for white wheat seeds ( Triticum aestivum ) for 696 chemicals and Douglas fir seeds ( Pseudotsuga menziesii ) for 81 chemicals. A similar repellency evaluation (REP) using a 5-day test with white wheat seeds at a 2.0% treatment rate was conducted with house mice and the results for 347 chemicals are presented. These toxicity and repellency data should be useful to those desiring to predict the potential for acute toxicity in wild mammals following exposure to a wide variety of chemicals. A calculation of the daily chemical dose ingested in mg/kg/day during the wheat test on deer mice and its resultant effects on mortality are also presented for most of the 696 chemicals. This calculated value, when used along with the ALD or LD 50 , should permit a rough estimate of the potential subacute toxicity of any tested chemical on wild mammals for which both types of data are available.

Archives of Environmental Contamination and Toxico↗
USGS1983

The acute oral toxicity, repellency, and hazard potential of 998 chemicals to one or more species of wild and domestic birds

The acute oral toxicity, repellency, and hazard potential of 998 chemicals to one or more of 68 species of wild and domestic birds was determined by standardized testing procedures. Red winged blackbirds were the most sensitive of the bird species tested on a large number of chemicals, and an index based on redwing toxicity and repellency may provide an appropriate indication of the probability of acute avian poisoning episodes. Avian repellency and toxicity were not positively correlated ( i.e. toxicity varied independently with repellency).

Archives of Environmental Contamination and Toxico↗
USGS1978

Short-tailed shrews: Toxicity and residue relationships of DDT, dieldrin, and endrin

Experiments involving dietary toxicity and residue relationships of DDT, dieldrin, and endrin were conducted with short-tailed shrews. Dietary concentrations of DDT dissolved in vegetable oils were usually more toxic than diets containing comparable amounts of powdered DDT. Younger shrews, particularly females, were more tolerant of powdered DDT than older animals; yet, there were no conspicuous age differences in toxicity of DDT dissolved in oils. In comparison to other mammals, short-tailed shrews are not unusually sensitive to DDT, dieldrin, or endrin on the basis of two-week feeding tests. The influence of age and sex on toxicity of DDT, endrin, and dieldrin was sometimes more important than body weight. Of those shrews of the same age and sex that were fed the same dietary dosage, heavier shrews were more tolerant than lighter individuals; and, heavier shrews tended to lose a greater percentage of body weight before death. There was a range of 15 to 105 DDT equivalents in brains of shrews dying on dietary dosages of DDT. Six shrews fed a high level of DDT seemed to have unusual metabolite capabilities and died with apparent lethal levels of DDD in their brains. Levels of dieldrin in brains of shrews that died on a dietary dosage of dieldrin ranged from 3.7 to 12.6 ppm. In the rates of gain and loss experiments where shrews were given diets containing 400 ppm DDT or 50 ppm dieldrin up to 17 days, high residues were noted in tissues of shrews after two weeks on a contaminated diet and a few died at that time. After shrews were placed on clean food, it was determined that >50% of the dieldrin residues in carcass and brain were lost in <2 weeks. Males and females fed DDT for 17 days lost >50% of residues of DDT and metabolites in brains after 2 weeks on clean food; males lost nearly 50% of residues in carcasses after two weeks on clean food compared with a loss of only 11% in females.

Archives of Environmental Contamination and Toxico↗
USGS2005

Acute toxicity of six freshwater mussel species (Glochidia) to six chemicals: Implications for daphnids and Utterbackia imbecillis as surrogates for protection of freshwater mussels (Unionidae)

Acute (24-h) toxicity tests were used in this study to compare lethality responses in early life stages (glochidia) of six freshwater mussel species, Leptodea fragilis, U. imbecillis, Lampsilis cardium, Lampsilis siliquoidea, Megalonaias nervosa, and Ligumia subrostrata, and two standard test organisms, Ceriodaphnia dubia and Daphnia magna. Concentrations of carbaryl, copper, 4-nonylphenol, pentachlorophenol, permethrin, and 2,4-D were used in acute exposures to represent different chemical classes and modes of action. The relative sensitivities of species were evaluated by ranking their LC 50 values for each chemical. We used these ranks to determine the extent to which U. imbecillis (one of the most commonly used unionids in toxicity tests) was representative of the tolerances of other mussels. We also calculated geometric mean LC50s for the families Unionidae and Daphnidae. Rankings of these data were used to assess the extent to which Daphnidae can be used as surrogates for freshwater mussels relative to chemical sensitivity. While no single chemical elicited consistently high or low toxicity estimates, carbaryl and 2,4-D were generally the least toxic to all species tested. No species was always the most sensitive, and Daphnidae were generally protective of Unionidae. Utterbackia imbecillis, while often proposed as a standard unionid mussel test species, did not always qualify as a sufficient surrogate (i.e., a substitute organism that often elicits similar sensitivity responses to the same contaminant exposure) for other species of mussels, since it was usually one of the more tolerant species in our rankings. U. imbecillis should be used as a surrogate species only with this caution on its relative insensitivity. ?? 2005 Springer Science+Business Media, Inc.

Archives of Environmental Contamination and Toxico↗
USGS2005

Assessing contaminant sensitivity of endangered and threatened aquatic species: Part III. Effluent toxicity tests

Toxicity tests using standard effluent test procedures described by the U.S. Environmental Protection Agency were conducted with Ceriodaphnia dubia, fathead minnows (Pimephales promelas), and seven threatened and endangered (listed) fish species from four families: (1) Acipenseridae: shortnose sturgeon (Acipenser brevirostrum); (2) Catostomidae; razorback sucker (Xyrauchen texanus); (3) Cyprinidae: bonytail chub (Gila elegans), Cape Fear shiner (Notropis mekistocholas) Colorado pikeminnow (Ptychocheilus lucius), and spotfin chub (Cyprinella monacha); and (4) Poecillidae: Gila topminnow (Poeciliopsis occidentalis). We conducted 7-day survival and growth studies with embryo-larval fathead minnows and analogous exposures using the listed species. Survival and reproduction were also determined with C. dubia. Tests were conducted with carbaryl, ammonia-or a simulated effluent complex mixture of carbaryl, copper, 4-nonylphenol, pentachlorophenol and permethrin at equitoxic proportions. In addition, Cape Fear shiners and spotfin chub were tested using diazinon, copper, and chlorine. Toxicity tests were also conducted with field-collected effluents from domestic or industrial facilities. Bonytail chub and razorback suckers were tested with effluents collected in Arizona whereas effluent samples collected from North Carolina were tested with Cape Fear shiner, spotfin chub, and shortnose sturgeon. The fathead minnow 7-day effluent test was often a reliable estimator of toxic effects to the listed fishes. However, in 21 % of the tests, a listed species was more sensitive than fathead minnows. More sensitive species results varied by test so that usually no species was always more or less sensitive than fathead minnows. Only the Gila topminnow was consistently less sensitive than the fathead minnow. Listed fish species were protected 96% of the time when results for both fathead minnows and C. dubia were considered, thus reinforcing the value of standard whole-effluent toxicity tests using those two species. If the responses of specific listed species are important for management decisions, our study supports the value in developing culture and testing procedures for those species. ?? 2005 Springer Science+Business Media, Inc.

Archives of Environmental Contamination and Toxico↗
USGS2005

Factors affecting the toxicity of methylmercury injected into eggs

We developed a standardized protocol for comparing the sensitivities of the embryos of different bird species to methylmercury when methylmercury was injected into their eggs. During the course of developing this protocol, we investigated the effects of various factors on the toxicity of the injected methylmercury. Most of our experiments were done with chicken ( Gallus domesticus ), mallard ( Anas platyrhynchos ), and ring-necked pheasant ( Phasianus colchicus ) eggs, all of which were purchased in large numbers from game farms. A smaller amount of work was done with double-crested cormorant ( Phalacrocorax auritus ) eggs collected from the wild. Several solvents were tested, and corn oil at a rate of 1 μl/g egg contents was selected for the final standardized protocol because it had minimal toxicity to embryos and because methylmercury dissolved in corn oil yielded a dose–response curve in a range of egg concentrations that was similar to the range that causes reproductive impairment when the mother deposits methylmercury into her own eggs. The embryonic stage at which eggs were injected with corn oil altered mercury toxicity; at early stages, the corn oil itself was toxic. Therefore, in the final protocol we standardized the time of injection to occur when each species reached the morphologic equivalent of a 3-day-old chicken embryo. Although solvents can be injected directly into the albumen of an egg, high embryo mortality can occur in the solvent controls because of the formation of air bubbles in the albumen. Our final protocol used corn oil injections into the air cell, which are easier and safer than albumen injections. Most of the methylmercury, when dissolved in corn oil, injected into the air cell passes through the inner shell membrane and into the egg albumen. Most commercial incubators incubate eggs in trays with the air cell end of the egg pointing upward, but we discovered that mercury-induced mortality was too great when eggs were held in this orientation. In addition, some species of bird eggs require incubation on their sides with the eggs being rolled 180° for them to develop normally. Therefore, we adopted a procedure of incubating the eggs of all species on their sides and rolling them 180° every hour. Little has been published about the conditions of temperature, humidity, and the movements to which eggs of wild birds need to be subjected for them to hatch optimally under artificial incubation. Not unexpectedly, hatching success in an artificial incubator is generally less than what natural incubation by the parents can achieve. However, the survival of control embryos of most wild bird species was good (generally ≥ 80%) up to within 1 or 2 days of hatching when we incubated the eggs at 37.5°C (or 37.6°C for gallinaceous species) at a relative humidity that resulted in an approximate 15% to 16% loss in egg weight by the end of incubation and by incubating the eggs on their sides and rolling them 180°/h. To improve statistical comparisons, we used survival through 90% of incubation as our measurement to compare survival of controls with survival of eggs injected with graded concentrations of mercury.

Archives of Environmental Contamination and Toxico↗
USGS2009

Toxicity of sediment cores collected from the Ashtabula River in northeastern Ohio, USA, to the amphipod Hyalella azteca

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 sediment-dwelling organisms. ?? 2009 US Government.

Archives of Environmental Contamination and Toxico↗
USGS2000

Developmental toxicity of lead-contaminated sediment to mallard ducklings

Sediment ingestion has been identified as an important exposure route for toxicants in waterfowl. The toxicity of lead-contaminated sediment from the Coeur d'Alene River Basin (CDARB) in Idaho was examined on posthatching development of mallard ( Anas platyrhynchos ) ducklings for 6 weeks. Day-old ducklings received either untreated control diet, clean sediment (24%) supplemented control diet, CDARB sediment (3,449 μg/g lead) supplemented diets at 12% or 24%, or a positive control diet containing lead acetate equivalent to that found in 24% CDARB. The 12% CDARB diet resulted in a geometric mean blood lead concentration of 1.41 ppm (WW) with over 90% depression of red blood cell ALAD activity and over threefold elevation of free erythrocyte protoporphyrin concentration. The 24% CDARB diet resulted in blood lead of 2.56 ppm with over sixfold elevation of protoporphyrin and lower brain weight. In this group the liver lead concentration was 7.92 ppm (WW), and there was a 40% increase in hepatic reduced glutathione concentration. The kidney lead concentration in this group was 7.97 ppm, and acid-fast inclusion bodies were present in the kidneys of four of nine ducklings. The lead acetate positive control group was more adversely affected in most respects than the 24% CDARB group. With a less optimal diet (mixture of two thirds corn and one third standard diet), CDARB sediment was more toxic; blood lead levels were higher, body growth and liver biochemistry (TBARS) were more affected, and prevalence of acid-fast inclusion bodies increased. Lead from CDARB sediment accumulated more readily in duckling blood and liver than reported in goslings, but at given concentrations was generally less toxic to ducklings. Many of these effects are similar to ones reported in wild mallards and geese within the CDARB.

Idaho↗
USGS2024

Toxicity of a management bait for grass carp (Ctenopharyngodon idella) incorporated with Antimycin A

No current technology can specifically target grass carp ( Ctenopharyngodon idella ) for control within aquatic ecosystems. Rotenone and Carbon Dioxide-Carp are currently the only available registered pesticides for grass carp; they are nonselective and typically applied throughout the water, equally exposing target and native species. A more selective control tool or pesticide application could be used by resource managers to support mitigation efforts. Development of delivery systems that exploit carp feeding strategies could increase selectivity of pesticides and minimize effects on native fishes. A pesticide with selective delivery could be less labor intensive and used within an integrative pest management strategy. The present study examined Antimycin A toxicity in juvenile and sub-adult grass carp and rainbow trout ( Oncorhynchus mykiss ) across two routes of exposure. Water-based toxicity studies were used to calculate the concentration to cause lethality in 50% of treated fish (LC 50 ) at 24-h, while oral gavage toxicity studies were used to calculate the dose to cause lethality in 50% of treated grass carp and rainbow trout (LD 50 ) 24- to 96-h. Although rainbow trout were more sensitive than grass carp to Antimycin A through water-based exposure, oral toxicity was similar between species, even with inherent gastrointestinal morphological differences. Successful delivery of a lethal dose of Antimycin A to grass carp was achieved through an oral route of exposure using the rapeseed bait and shows promise for registration as a control tool and eventual use in pest management plans. Although a lethal dose of Antimycin A could be incorporated into a single bait pellet, more bait was required to achieve desired mortality when fed to fish under laboratory conditions.

Ecotoxicology↗
USGS2026

Tissue metal concentrations and toxicity in wild turkeys following chronic exposure to mining-contaminated soils in southeast Missouri, USA

The Big River watershed in southeast Missouri (SEMO) is a Superfund site with an extensive history of lead (Pb) and zinc (Zn) mining; cadmium (Cd) and other metals also occur in the ore and waste materials. We examined whether SEMO wild turkeys ( Meleagris gallopavo ) exposed to mining-contaminated floodplain soils and food resources in the Big River watershed had elevated metal concentrations in their tissues, indicating Pb poisoning and associated toxic effects. Compared to reference birds ( n = 15) harvested in northern Missouri, SEMO turkeys ( n = 23) had significantly elevated Pb concentrations in ventricular content, liver, kidney, bone and contour feathers. Liver and kidney from SEMO turkeys also contained significantly elevated Cd concentrations compared to reference birds. Grit (2.8–5.6 mm) from turkeys ( n = 1 reference; n = 6 SEMO) was within the size range of coarse sediments reported to contain toxic metal concentrations, and 63% of turkeys harvested within 4 km of the Big River floodplain had tissue concentrations that exceeded avian thresholds for Pb poisoning. Tissue concentrations of Pb were significant predictors of keel hemorrhage as well as reductions in testis weight and bone Zn concentration. These sublethal endpoints suggest that chronic metal exposure in SEMO turkeys may be inducing toxic effects at lower tissue metal concentrations than would be estimated by current avian toxicity thresholds. These findings highlight the need for decision makers to consider how metal contamination may affect local turkey health and abundance, and the need for data-driven guidance for the safe consumption of wild foods harvested in SEMO and other mining-affected sites.

Missouri↗
USGS1980

Toxic effects of endrin and toxaphene on the southern leopard frog Rana sphenocephala

Eggs, larvae and sub-adults of the southern leopard frog Rana sphenocephala were exposed to endrin and toxaphene. Exposure was in water by a continuous-flow technique, following standards that have been used successfully in the study of fish and invertebrates. R. sphenocephala is more sensitive to both pesticides than are higher vertebrates but is slightly less sensitive than fish. Eggs seem to be resistant to the effects of both pesticides and are probably poor indicators of environmental hazard. The toxic level of endrin is about equal in larvae and transformed frogs (LC 50 , 0·005-0·015 ppm). Toxaphene is less toxic to sub-adults (LC 50 , 0·37-0·790 ppm) than to larvae (LC 50 , 0·032-0·054 ppm). Delayed mortality, behavioural aberrations and effects on growth have been seen in toxaphene-dosed larvae observed over 30-day periods. Behavioural effects are more severe than those reported in other groups of animals. Effects on growth resulting from a 96-h exposure begin in the 0·013-0·018 ppm range. The maximum accumulation of residues observed for each chemical represented bioconcentration factors of about 100. Endrin residues are apparently lost more readily than toxaphene residues; relative depuration rates correlate well with the time course of toxic action in each chemical. Although less sensitive to these pesticides than fish, amphibians may not be protected in their natural habitats. Future studies of the effects of toxicants on amphibians should employ larvae if only one stage can be tested, should expose subjects for at least 96 h and should continue observations for a total of at least 30 days.

Maryland↗
USGS2020

Relative toxicity and sublethal effects of NaCl and energy-related saline wastewaters on prairie amphibians

Increasing salinity in freshwater environments is a growing problem due both to the negative influences of salts on ecosystems and their accumulation and persistence in environments. Two major sources of increased salinity from sodium chloride salts (NaCl) are saline wastewaters co-produced during energy production (herein, wastewaters) and road salts. Effects of road salts have received more attention, but legacy contamination from wastewaters is widespread in some regions and spills still occur. Amphibians are sensitive to contaminants, including NaCl, because of their porous skin and osmoregulatory adaptations to freshwater. However, similarities and differences between effects of wastewaters and road salts have not been investigated. Therefore, we investigated the relative influence of wastewaters and NaCl at equivalent concentrations of chloride on three larval amphibian species that occur in areas with increased salinity. We determined acute toxicity and growth effects on Boreal Chorus Frogs ( Pseudacris maculata ), Northern Leopard Frogs ( Rana pipiens ), and Barred Tiger Salamanders ( Ambystoma mavortium ). We posited that wastewaters would have additive effects on amphibians compared to NaCl because wastewaters often have additional toxic heavy metals and other contaminants. For NaCl, toxicity was higher for frogs than the salamander. Toxicity of wastewaters was also similar between chorus and leopard frogs. Only chorus frog survival was lower when exposed to wastewater compared to NaCl. Mass and length of leopard and chorus frog larvae decreased with increasing salinity after only 96 hours of exposure but did not for tiger salamanders. Size of leopard frogs was lower when exposed to NaCl compared to wastewater. However, growth effects were similar between wastewater and NaCl for chorus frogs. Taken together, our results suggest that previous studies on effects of road salt could inform future studies and management of wastewater-contaminated ecosystems, and vice versa. Nevertheless, effects of road salts and wastewaters may be context-, species-, and trait-specific and require further investigations. The negative influence of salts on imperiled amphibians underscores the need to restore landscapes with increased salinity and reduce future salinization of freshwater ecosystems.

Aquatic Toxicology↗