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USGS2000

Organochlorine and trace element contamination in wintering and migrating diving ducks in the southern Great Lakes, USA, since the zebra mussel invasion

Because of the potential for increased trophic transfer of contaminants by zebra mussels ( Dreissena sp. ) to higher trophic levels, we collected four species of waterfowl (n = 65 ducks) from four locations in Lake Erie, Lake St. Clair, and Lake Michigan, USA, between 1991 and 1993 for organochlorine contaminant and trace element analyses. Geometric mean concentrations of total polychlorinated biphenyls (PCBs) and p , p ′-dichlorodiphenyldichloroethylene (DDE) were 1.35 and 0.15 μg/g wet weight in lesser scaup ( Aythya affinis ) carcasses and were below known effect levels. Total PCBs in 80% of carcasses, however, were above the U.S. Food and Drug Administration's threshold of 3.0 μg/g lipid weight for consumption of poultry. With the exception of selenium, trace elements were also at background or no-effect levels. Selenium concentrations in livers of 95% of lesser scaup, 90% of bufflehead ( Bucephala albeola ), and 72% of common goldeneye ( Bucephala clangula ) were in the elevated (>10 μg/g dry wt) or potentially harmful range (>33 μg/g dry wt). The effects of these high selenium concentrations are unknown but should be investigated further based on reproductive effects observed in field and laboratory studies of dabbling ducks and because lesser scaup populations are declining. Concentrations of total PCBs in dreissenid mussels in western Lake Erie were 10 times higher than in the upper Mississippi River but were similar to concentrations in other industrialized rivers in Europe and the United States. Metal concentrations were similar to other industrialized sites where zebra mussels have been sampled.

Indiana, Michigan, Ohio↗

USGS1993

Environmental contaminants in bald eagle eggs—1980–84—and further interpretations of relationships to productivity and shell thickness

Bald eagle ( Haliaeetus leucocephalus ) eggs were collected in 15 States in the United States in 1980–1984 and analyzed for organochlorine pesticides, polychlorinated biphenyls (PCBs), and mercury. Data were compared and combined with data from earlier studies to examine trends and refine relationships of contaminants to shell thickness and young production. Moderate shell thinning occurred in eggs from several States. The frequency of occurrence of detectable residues of several contaminants declined during 1969–84. DDE concentrations declined significantly in Wisconsin, Maine, and the Chesapeake Bay region. Some other contaminant residues declined, but usually not significantly. During 1980–84, DDE, PCB, and mercury concentrations were highest in eggs from Maine, whereas most contaminant concentrations were lowest in eggs from Arizona. DDE was most closely related to shell thickness and young production at sampled breeding areas. Fifteen percent shell thinning was associated with 16 μg/g DDE (wet weight) for eggs collected early in incubation. Young production was normal when eggs at sampled breeding areas contained < 3.6 μg/g DDE (wet weight), was nearly halved between 3.6 to 6.3 μg/g, and halved again when concentrations exceeded 6.3 μg/g. Several other contaminants were also associated with poor reproduction and eggshell thinning; however, their impact appeared to be secondary to that of DDE and was probably related to their high correlation with DDE. Data relating contaminant concentrations to mean 5-year production are applicable only to breeding areas where eggs are collected after failure to hatch, because such breeding areas are not representative of all nesting bald eagles in a given population.

Archives of Environmental Contamination and Toxico↗

USGS1989

Microcontaminants and reproductive impairment of the Forster's tern on Green Bay, Lake Michigan,1983

For the 1983 nesting season, Forster's tern ( Sterna forsteri ) reproductive success was significantly impaired on organochlorine contaminated Green Bay, Lake Michigan compared to a relatively uncontaminated inland location at Lake Poygan, Wisconsin. Compared with tern eggs from Lake Poygan, eggs from Green Bay had significantly higher median concentrations of 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD), other polychlorinated dibenzo- p -dioxins (PCDDs), total polychlorinated biphenyls (PCBs), total (three congeners) non-ortho, ortho' PCBs, five individual PCB congeners known to induce aryl hydrocarbon hydroxylase (AHH) and several other organochlorine contaminants. Conversions of analytical concentrations of TCDD and PCB congeners based on relative AHH induction potencies allowed for estimation of total 2,3,7,8-TCDD equivalents. Two PCB congeners, 2,3,3′,4,4′- and 3,3′,4,4′,5-pentachlorobiphenyl (PeCB) accounted for more than 90% of the median estimated TCDD equivalents at both Green Bay and Lake Poygan. The median estimated TCDD equivalents were almost 11-fold higher in tern eggs from Green Bay than in eggs from Lake Poygan (2175 and 201 pg/g). The hatching success of Green Bay sibling eggs from nests where eggs were collected for contaminant analyses was 75% lower at Green Bay than at Lake Poygan. Hatchability of eggs taken from other nests and artificially incubated was about 50% lower for Green Bay than for Lake Poygan. Among hatchlings from laboratory incubation, those from Green Bay weighed approximately 20% less and had a mean liver weight to body weight ratio 26% greater than those from Lake Poygan. In both field and laboratory, mean minimum incubation periods were significantly longer for eggs from Green Bay compared to Lake Poygan (8.25 and 4.58 days, respectively). Mean minimum incubation time for Green Bay eggs in the field was 4.37 days longer than in the laboratory. Hatchability was greatly improved when Green Bay eggs were incubated by Lake Poygan adults in an egg-exchange experiment, but was sharply decreased in Lake Poygan eggs incubated in Green Bay nests. Nest abandonment and egg disappearance were substantial at Green Bay but nil at Lake Poygan. Thus, not only factors intrinsic to the egg, but also extrinsic factors (parental attentiveness), impaired reproductive outcome at Green Bay. The epidemiological evidence from this study strongly suggested that contaminants were a causal factor. AHH-active PCB congeners (intrinsic effects) and PCBs in general (extrinsic effects) appeared to be the only contaminants at the concentrations measured in eggs, capable of producing the effects that were observed at Green Bay.

Wisconsin↗

USGS1998

Overview of a workshop on screening methods for detecting potential (anti-) estrogenic/androgenic chemicals in wildlife

The U.S. Congress has passed legislation requiring the U.S. Environmental Protection Agency (U.S. EPA) to develop, validate, and implement screening tests for identifying potential endocrine-disrupting chemicals within 3 years. To aid in the identification of methods suitable for this purpose, the U.S. EPA, the Chemical Manufacturers Association, and the World Wildlife Fund sponsored several workshops, including the present one, which dealt with wildlife species. This workshop was convened with 30 international scientists representing multiple disciplines in March 1997 in Kansas City, Missouri, USA. Participants at the meeting identified methods in terms of their ability to indicate (anti-) estrogenic/androgenic effects, particularly in the context of developmental and reproductive processes. Data derived from structure-activity relationship models and in vitro test systems, although useful in certain contexts, cannot at present replace in vivo tests as the sole basis for screening. A consensus was reached that existing mammalian test methods (e.g., with rats or mice) generally are suitable as screens for assessing potential (anti-) estrogenic/ androgenic effects in mammalian wildlife. However, due to factors such as among-class variation in receptor structure and endocrine function, it is uncertain if these mammalian assays would be of broad utility as screens for other classes of vertebrate wildlife. Existing full and partial life-cycle tests with some avian and fish species could successfully identify chemicals causing endocrine disruption; however, these long-term tests are not suitable for routine screening. However, a number of short-term tests with species from these two classes exist that could serve as effective screening tools for chemicals inducing (anti-) estrogenic/androgenic effects. Existing methods suitable for identifying chemicals with these mechanisms of action in reptiles and amphibians are limited, but in the future, tests with species from these classes may prove highly effective as screens. In the case of invertebrate species, too little is known at present about the biological role of estrogens and androgens in reproduction and development to recommend specific assays.

Environmental Toxicology and Chemistry↗

USGS2002

Role of selenium toxicity and oxidative stress in aquatic birds

Adverse effects of selenium (Se) in wild aquatic birds have been documented as a consequence of pollution of the aquatic environment by subsurface agricultural drainwater and other sources. These effects include mortality, impaired reproduction with teratogenesis, reduced growth, histopathological lesions and alterations in hepatic glutathione metabolism. A review is provided, relating adverse biological effects of Se in aquatic birds to altered glutathione metabolism and oxidative stress. Laboratory studies, mainly with an organic form of Se, selenomethionine, have revealed oxidative stress in different stages of the mallard (Anas platyrhynchos) life cycle. As dietary and tissue concentrations of Se increase, increases in plasma and hepatic GSH peroxidase activities occur, followed by dose-dependent increases in the ratio of hepatic oxidized to reduced glutathione (GSSG:GSH) and ultimately hepatic lipid peroxidation measured as an increase in thiobarbituric acid reactive substances (TBARS). One or more of these oxidative effects were associated with teratogenesis (4.6 ppm wet weight Se in eggs), reduced growth in ducklings (15 ppm Se in liver), diminished immune function (5 ppm Se in liver) and histopathological lesions (29 ppm Se in liver) in adults. Manifestations of Serelated effects on glutathione metabolism were also apparent in field studies in seven species of aquatic birds. Reduced growth and possibly immune function but increased liver:body weight and hepatic GSSG:GSH ratios were apparent in American avocet (Recurvirostra americana) hatchlings from eggs containing 9 ppm Se. In blacknecked stilts (Himantopus mexicanus), which contained somewhat lower Se concentrations, a decrease in hepatic GSH was apparent with few other effects. In adult American coots (Fulica americana), signs of Se toxicosis included emaciation, abnormal feather loss and histopathological lesions. Mean liver concentrations of 28 ppm Se (ww) in the coots were associated with elevated hepatic GSH peroxidase, depletion of hepatic protein bound thiols and total thiols, but a small increase in GSH. Diving ducks in the San Francisco Bay area exhibited a positive correlation between hepatic Se concentration and GSH peroxidase activity (r=0.63, P<0.05), but a negative correlation between hepatic Se and GSH concentration (r=0.740, P<0.05). In willets (Catoptrophorus semipalmatus) from the San Diego area, positive correlations occurred between hepatic Se concentration and GSSG (r=0.70, P<0.001), GSSG:GSH ratio, and TBARS. In emperor geese (Chen canagica) from western Alaska, blood levels of up to 9.4 ppm occurred and were associated with increased plasma GSH peroxidase activity (r=0.62, P<0.001), but with decreased plasma GSSG reductase activity. When evaluating Se toxicity, interactive nutritional factors, including other elements and dietary protein, should also be taken into consideration. Further studies are needed to examine the relationship between different forms of environmentally occurring selenium, arsenic and mercury on reproduction, hepatotoxicity and immune function of aquatic birds. Further selenium nutritional interaction studies may also help to illucidate the mechanism of selenium induced teratogenesis, by optimizing GSH and other antioxidant defense mechanisms in a manner that would stabilize or raise the cell's threshold for susceptibility to toxic attack from excess selenium. It is concluded that Se-related manifestations of oxidative stress may serve as useful bioindicators of Se exposure and toxicity in wild aquatic birds.

Aquatic Toxicology↗

USGS2009

Observed and predicted reproduction of Ceriodaphnia dubia exposed to chloride, sulfate, and bicarbonate

Chronic toxicities of Cl - , SO 4 2- , and HCO 3 - to Ceriodaphnia dubia were evaluated in low- and moderate-hardness waters using a three-brood reproduction test method. Toxicity tests of anion mixtures were used to determine interaction effects and to produce models predicting C. dubia reproduction. Effluents diluted with low- and moderate-hardness waters were tested with animals acclimated to low- and moderate-hardness conditions to evaluate the models and to assess the effects of hardness and acclimation. Sulfate was significantly less toxic than Cl - and HCO 3 - in both types of water. Chloride and HCO 3 - toxicities were similar in low-hardness water, but HCO 3 - was the most toxic in moderate-hardness water. Low acute-to-chronic ratios indicate that toxicities of these anions will decrease quickly with dilution. Hardness significantly reduced Cl - and SO 4 2- toxicity but had little effect on HCO 3 - . Chloride toxicity decreased with an increase in Na + concentration, and CO 3 - toxicity may have been reduced by the dissolved organic carbon in effluent. Multivariate models using measured anion concentrations in effluents with low to moderate hardness levels provided fairly accurate predictions of reproduction. Determinations of toxicity for several effluents differed significantly depending on the hardness of the dilution water and the hardness of the water used to culture test animals. These results can be used to predict the contribution of elevated anion concentrations to the chronic toxicity of effluents; to identify effluents that are toxic due to contaminants other than Cl - , SO 4 2- , and HCO 3 - ; and to provide a basis for chemical substitutions in manufacturing processes.

Environmental Toxicology and Chemistry↗

USGS1991

H4IIE rat hepatoma cell bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in colonial fish-eating waterbird eggs from the Great Lakes

Fish-eating waterbirds from the Great Lakes of North America have shown symptoms of poisoning similar to those observed in laboratory exposures of various avian species to planar halogenated hydrocarbons (PHHs). PHHs, include among others, polychlorinated biphenyls (PCBs), polychlorinated dibenzo- p -dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) and have been implicated in some of the reproductive problems of Great Lakes waterbirds. The objectives of this study were to assess the overall potencies of PCB-containing extracts from colonial water-bird eggs taken from the Great Lakes and to compare the potencies with the location and spatial distribution of the colonies. The potencies of the extracts were assessed by their ability to induce cytochrome P450IA1-associated ethoxyresorufin O-deethylase (EROD) activity in H4IIE rat hepatoma cells as compared to the standard, 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD). The H4IIE bioassay-derived TCDD-equivalents (TCCD-EQs) in the waterbird eggs concur with residue analyses and biological data from other studies. The greatest concentrations of TCDD-EQs were found in waterbird eggs from historically polluted, industrialized or urbanized areas in which the reproductive impairment of colonial waterbirds was most severe. However, significant concentrations of TCDD-EQs were detected at all sites tested; with a range of 49 to 415 pg TCDD-EQ/g egg, uncorrected for extraction efficiencies. The H4IIE bioassay proved to be a useful biomonitoring tool to assess the overall potency of complex PHH mixtures in environmental samples.

Beaver Island Group, Green Bay, Lake Erie, Lake Hu↗

USGS2001

Development of marine toxicity data for ordnance compounds

A toxicity database for ordnance compounds was generated using eight compounds of concern and marine toxicity tests with five species from different phyla. Toxicity tests and endpoints included fertilization success and embryological development with the sea urchin Arbacia punctulata ; zoospore germination, germling length, and cell number with the green macroalga Ulva fasciata ; survival and reproductive success of the polychaete Dinophilus gyrociliatus ; larvae hatching and survival with the redfish Sciaenops ocellatus ; and survival of juveniles of the opossum shrimp Americamysis bahia (formerly Mysidopsis bahia ). The studied ordnance compounds were 2,4- and 2,6-dinitrotoluene, 2,4,6-trinitrotoluene, 1,3-dinitrobenzene, 1,3,5-trinitrobenzene, 2,4,6-trinitrophenylmethylnitramine (tetryl), 2,4,6-trinitrophenol (picric acid), and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). The most sensitive toxicity test endpoints overall were the macroalga zoospore germination and the polychaete reproduction tests. The most toxic ordnance compounds overall were tetryl and 1,3,5-trinitrobenzene. These were also the most degradable compounds, often being reduced to very low or below-detection levels at the end of the test exposure. Among the dinitro- and trinitrotoluenes and benzenes, toxicity tended to increase with the level of nitrogenation. Picric acid and RDX were the least toxic chemicals tested overall.

Archives of Environmental Contamination and Toxico↗

USGS2018

Polychlorinated biphenyl tissue‐concentration thresholds for survival, growth, and reproduction in fish

Polychlorinated biphenyls (PCBs) have left a legacy of environmental contamination. Even though they were banned from production and active use in the 1970s, they persist in the environment and still have the potential to impact aquatic life. Our objective was to identify data from controlled laboratory studies of PCB‐related adverse effects in fish and to conduct a meta‐analysis on mortality, growth, and reproductive (MGR) threshold responses. For each endpoint type, we compiled data on the lowest‐observed‐adverse effect concentration (LOAEC) and the degree of effect at the LOAEC as a percentage of control. The LOAECs were expressed as tissue concentrations, so the term lowest‐observed‐adverse‐effect residue concentration (LOAER) was used to represent PCB exposures. The lower limit of applicability was set at 0.1 μg/g total PCB tissue concentration, below which adverse MGR effects in fish were not supported by the data. Sensitivity distributions identifying the probability of adverse effects in fish populations or communities predicted that 25% of fish species would be impacted between 0.1 and 7.5 μg/g. Concentration–response threshold regressions were developed from the MGR datasets. For example, a 1 μg/g total PCB tissue concentration would predict effects of 17% mortality, 15% growth, and 39% reproductive. The analysis determined the degree of adverse response, with uncertainty estimates, expected across a broad range of PCB tissue exposure concentrations in fish. Data generated from MGR endpoints were combined to determine an approach for overall effect thresholds for PCB‐related injury in fish. The MGR datasets included only laboratory data; however, responses were compared with field‐observed effects. The present review provides a comprehensive assessment of PCB‐induced injury in fish utilizing a data‐inclusive approach.

Environmental Toxicology and Chemistry↗

USGS2000

Environmental contaminants in Texas, USA, wetland reptiles: Evaluation using blood samples

Four species of reptiles (diamondback water snake [ Nerodia rhombifer ], blotched water snake [ N. erythrogaster ], cottonmouth [ Agkistrodon piscivorus ], and red-eared slider [ Trachemys scripta ]) were collected at two contaminated and three reference sites in Texas, USA. Old River Slough has received intensive applications of agricultural chemicals since the 1950s. Municipal Lake received industrial arsenic wastes continuously from 1940 to 1993. Blood samples were analyzed for organochlorines, potentially toxic elements, genetic damage, and plasma cholinesterase (ChE). Dichlorodiphenyldichloroethylene (DDE) concentrations reached as high as 3.0 ppm (wet weight) in whole blood of a diamondback water snake at Old River Slough, a level probably roughly equivalent to the maximum concentration found in plasma of peregrine falcons ( Falco peregrinus ) in 1978 to 1979 when DDE peaked in this sensitive species. Possible impacts on diamondback water snakes are unknown, but at least one diamondback water snake was gravid when captured, indicating active reproduction. Arsenic was not found in red-eared sliders (only species sampled) from Municipal Lake. Red-eared sliders of both sexes at Old River Slough showed declining levels of ChE with increasing mass, suggesting a life-long decrease of ChE levels. Possible negative population consequences are unknown, but no evidence was found in body condition (mass relative to carapace length) that red-eared sliders at either contaminated site were harmed.

Texas↗

USGS1992

Trace element and organochlorine concentrations in California clapper rail (Rallus longirostris obsoletus) eggs

Trace contaminant concentrations were measured in eggs of endangered California clapper rails ( Rallus longirostris obsoletus ) collected from San Francisco Bay during 1975, 1986, and 1987, and in clapper rail eggs ( R. l. waynei ) from North Carolina during 1987. Residues of 10 detected organochlorines (OC) were low and decreased by 2 to 3-fold from 1975 to 1986–1987 for San Francisco Bay samples, whereas eggshell thickness remained unchanged and comparable to eggs collected prior to 1940. Mercury (Hg) concentrations in eggs from San Francisco Bay were higher than those from North Carolina, and comparable to concentrations associated with reproductive effects in other avian species. Selenium (Se) concentrations in eggs from San Francisco Bay were also higher than those from North Carolina, and were highest in a north San Francisco Bay marsh adjacent to an oil refinery. Individual Se concentrations were slightly lower than values associated with embryotoxicity in other rallids. We recommend additional research on the effects of these and other contaminants on California clapper rails and the restoration of rail habitat.

California↗

USGS2025

Biological implications for contaminants of emerging concern in the Great Lakes–Upper St Lawrence River drainage: An effect-based ecological hazard assessment in fish

Contaminants of emerging concern (CECs) are released widely and continuously into the Great Lakes Basin–Upper St Lawrence River study area, with many detected in surface water at concentrations known to adversely affect fish. We applied a recent ecological hazard assessment methodology to identify the biological significance of a database of 21,441 surface water CEC concentrations compiled from 7,162 surface water samples collected at 1,021 sampling sites in 387 individual waterbodies throughout the Great Lakes Basin. We assessed hazard to fish in 12 effect categories (e.g., mortality, developmental, reproductive) from aqueous exposure to 16 emerging contaminants. Our hazard assessment used pairs of screening values to generate contaminant- and effect-specific ordinal hazard scores. Using this novel methodology, we generated a database of 93,864 hazard scores. We found the highest level of hazard to fish, indicating probable adverse impacts, was broadly distributed and often associated with municipalities. Mortality, reproductive, and developmental effect categories combined accounted for 17.5% of high hazard observations. Low hazard, indicating possible adverse effects, was prevalent for numerous effect categories and occurred throughout the period 1991–2021. For mortality, reproductive, and developmental effect categories, the incidence of elevated hazard (low or high hazard) among assessed water samples was 20.4%, 39.5%, and 20.3%, respectively. On a local scale, effect-based assessment is an efficient and conceptually simple tool for natural resource managers to obtain effect- and site-specific hazard information concerning CEC effects in fish that can be used in project planning and results interpretation for natural resource monitoring, restoration, and protection.

Great Lakes–Upper St Lawrence River study area↗

USGS2016

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

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

Environmental Toxicology and Chemistry↗

USGS1990

Toxicity of inorganic and organic selenium to Daphnia magna (cladocera) and Chironomus riparius (diptera)

Elevated concentrations of selenium (Se) have been previously measured in biota sampled from the Kesterson National Wildlife Refuge (KNWR) in the San Joaquin Valley of central California. We conducted acute and chronic toxicity tests with the cladoceran Daphnia magna and the midge Chironomus riparius to determine the toxicity or bioaccumulation of waterborne Se in a reconstituted water similar to the San Joaquin River. Daphnids were more acutely sensitive than midges to the toxic effects of inorganic Se. An organic form of Se (seleno-[L]-methionine) was extremely toxic to daphnids, but was relatively nontoxic to midges. In long-term exposure to a 6:1 mixture of selenate to selenite (a mixture representative of KNWR), the emergence time of adult midges was delayed at Se concentrations ≥ 837 μg/L. Daphnid reproduction and intrinsic rate of natural increase ( r ) were reduced at Se concentrations ≥ 348 μg/L and growth of adults was reduced at ≥ 156 μg/L. Whole body Mg, K and Na concentrations in daphnids were not affected by chronic Se exposure; however, whole body Ca concentration increased at intermediate Se exposure concentrations. In addition, whole body Cl concentration was reduced at 711 μg Se/L. Daphnids accumulated potentially toxic concentrations of Se from water that may adversely affect fish or waterfowl through the food chain.

Environmental Toxicology and Chemistry↗

USGS1994

Acute and chronic effects of four commercial herbicide formulations on Ceriodaphnia dubia

Toxicity tests with Ceriodaphnia dubia were conducted to determine acute (48 h) and chronic (7-day survival and reproduction) effects of four commonly used herbicide formulations. The 48-h LC50s in decreasing order of toxicity were 14.36 mg/L (Micro-Tech ® ), 15.93 mg/L (Bicep ® ), 32.99 mg/L (Extrazine ® ), and 35.36 mg/L (Lexone ® ). Reduced reproduction was detected at concentrations below 48-h LC50s for three of the formulations. The 7-day chronic values (ChV) based on reproduction were 17.68 mg/L (Micro-Tech ® ), 8.84 mg/L (Bicep ® ), 17.68 mg/L (Extrazine ® ), and 8.84 mg/L (Lexone ® ). The acute-to-chronic ratios (ACRs) for Micro-Tech ® (0.81), Bicep ® (1.80), Extrazine ® (1.86), and Lexone ® (4.00) indicate a relatively narrow range between acute and chronic sensitivity in daphnids. A comparison of these response data to environmental concentrations suggests these herbicides are not likely to directly impact invertebrates. Potential impacts on plants and human health should be of primary ecological and regulatory concern.

Archives of Environmental Contamination and Toxico↗

USGS2012

Species-specific and transgenerational responses to increasing salinity in sympatric freshwater gastropods

Freshwater salinization is a global concern partly attributable to anthropogenic salt contamination. The authors examined the effects of increased salinity (as NaCl, 250-4,000 µS/cm, specific conductance) on two sympatric freshwater gastropods ( Helisoma trivolvis and Physa pomillia ). Life stage sensitivities were determined by exposing naive eggs or naive juveniles (through adulthood and reproduction). Additionally, progeny eggs from the juvenile-adult exposures were maintained at their respective parental salinities to examine transgenerational effects. Naive H. trivolvis eggs experienced delayed development at specific conductance > 250 µS/cm; reduced survivorship and reproduction were also seen in juvenile H. trivolvis at 4,000 µS/cm. Survival and growth of P. pomilia were not affected by increased salinity following egg or juvenile exposures. Interestingly, the progeny of H. trivolvis exposed to higher salinity may have gained tolerance to increased salinity whereas P. pomilia progeny may have experienced negative transgenerational effects. The present study demonstrates that freshwater snail species vary in their tolerance to salinization and also highlights the importance of multigenerational studies, as stressor impacts may not be readily apparent from shorter term exposures.

Environmental Toxicology and Chemistry↗

USGS2002

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

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

New Mexico↗

USGS1974

Effects of low dietary levels of methyl mercury on mallard reproduction

Mallard ducks were fed a control diet or a diet containing 0.5 ppm or 3 ppm mercury (as methylmercury dicyandiamide). Health of adults and reproductive success were studied. The dietary level of 3 ppm mercury had harmful effects on reproduction, although it did not appear to affect the health of the adults during the 12 months of dosage. Ducks that were fed the diet containing 0.5 ppm mercury reproduced as well as controls, and ducklings from parents fed 0.5 ppm mercury grew faster in the first week of life than did controls....The greatest harm to reproduction associated with the diet containing 3 ppm mercury was an increase in duckling mortality, but reduced egg laying and increased embryonic mortality also occurred....During the peak of egg laying, eggs laid by controls tended to be heavier than eggs laid by ducks fed either level of mercury; however, there seemed to be no eggshell thinning associated with mercury treatment. Levels of mercury reached about 1 ppm in eggs from ducks fed a dietary dosage of 0.5 ppm mercury and between 6 and 9 ppm in the eggs from ducks fed 3 ppm mercury.

Bulletin of Environmental Contamination and Toxico↗