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USGS2006

Interlaboratory evaluation of Hyalella azteca and Chironomus tentans short-term and long-term sediment toxicity tests

Methods for assessing the long-term toxicity of sediments to Hyalella azteca and Chironomus tentans can significantly enhance the capacity to assess sublethal effects of contaminated sediments through multiple endpoints. Sublethal tests allow us to begin to understand the relationship between short-term and long-term effects for toxic sediments. We present an interlaboratory evaluation with long-term and 10-d tests using control and contaminated sediments in which we assess whether proposed and existing performance criteria (test acceptability criteria [TAC]) could be achieved. Laboratories became familiar with newly developed, long-term protocols by testing two control sediments in phase 1. In phase 2, the 10-d and long-term tests were examined with several sediments. Laboratories met the TACs, but results varied depending on the test organism, test duration, and endpoints. For the long-term tests in phase 1, 66 to 100% of the laboratories consistently met the TACs for survival, growth, or reproduction using H. azteca , and 70 to 100% of the laboratories met the TACs for survival and growth, emergence, reproduction, and hatchability using C. tentans . In phase 2, fewer laboratories participated in long-term tests: 71 to 88% of the laboratories met the TAC for H. azteca , whereas 50 to 67% met the TAC for C. tentans . In the 10-d tests with H. azteca , and C. tentans , 82 and 88% of the laboratories met the TAC for survival, respectively, and 80% met the TAC for C. tentans growth. For the 10-d and long-term tests, laboratories predicted similar toxicity. Overall, the interlaboratory evaluation showed good precision of the methods, appropriate endpoints were incorporated into the test protocols, and tests effectively predicted the toxicity of sediments.

Environmental Toxicology and Chemistry↗

USGS1986

Wildlife in some areas of New Mexico and Texas accumulate elevated DDE residues, 1983

Over the last decade, data gathered by the U.S. Fish & Wildlife Service's National Contaminant Biomonitoring Program have identified an area of elevated DDE contamination in portions of New Mexico and Texas. Extensive wildlife sampling in 1983 confirmed that DDE, the major metabolite of the insecticide DDT, was present at high concentrations in wildlife at selected sites in the Rio Grande and Pecos River drainages. DDE in carcasses ranged up to 47 ppm (wet weight) in western kingbirds ( Tyrannus verticalis ), 35 ppm in house sparrows ( Passer domesticus ), 46 ppm in Brazilian free-tailed bats ( Tadarida brasiliensis ), and 104 ppm in whiptail lizards ( Cnemidophorus spp.). DDE was also detected in gut contents from western kingbirds at some of the highest concentrations ever reported, ranging up to 21 ppm in proventricular samples. An average of 40% of the eggs of black-crowned night-herons ( Nycticorax nycticorax ) from two sites along the Pecos River in New Mexico had DDE levels (≥8 ppm) that have been associated in other studies with impaired reproduction. In contrast, wintering mallards ( Anas platyrhynchos ) and American coots ( Fulica americana ) from the study area did not accumulate elevated DDE levels. DDE in wildlife samples at control sites (nonagricultural areas) was either absent or averaged less than 0.35 ppm. Collectively, these data provide evidence that there is major DDE contamination of several vertebrate species in portions of the Rio Grande and Pecos River drainages, but whether the contamination is recent or residual was not determined. Apparently, the source was not DDE contamination present in dicofol (4-chloro- a -(4-chlorophenyl)- a -(trichloromethyl) benzenemethanol); neither dicofol nor its metabolite, p,p' -dichlorobenzophenone, were detected in wildlife carcasses (0.1 ppm detection limit) or proventricular contents (0.01 ppm detection limit) of western kingbirds.

New Mexico, Texas↗

USGS2000

Energetic dose: Beyond fire and flint?

Nutritional and bioenergetic interactions influence exposure to environmental chemicals and may affect the risk realized when wildlife are exposed in the field. Here, food-chain analysis focuses on prairie voles (Microtus ochrogaster) and the evaluation of chemical risks associated with paraquat following 10-d dietary exposures. Reproductive effects were measured in 60-d trials that followed exposures to paraquat-tainted feed: control (untainted feed); 21 mg paraquat/kg feed; 63 mg paraquat/kg feed; and feed-restricted control (untainted feed restricted to 60% baseline consumption). Reproductive success was evaluated in control and treated breeding pairs, and a preliminary bioenergetics analysis was completed in parallel to derive exposure dose. Although reproductive performance differed among groups, feed-restriction appeared to be the dominant treatment effect observed in these 10-d feeding exposure/limited reproductive trials. Exposure dose ranged from 3.70-3.76 to 9.41-11.51 mg parquat/kg BW/day at 21 and 63 mg paraquat/kg feed stock exposures, respectively. Energetic doses as ug paraquat/kcal yielded preliminary estimates of energetic costs associated with paraquat exposure, and were similar within treatments for both sexes, ranging from 4.2-5.5 and 13.1-15.0 ug paraquat/kcal for voles exposed to 21 mg/kg feed stock and 63 mg/kg feed stock, respectively. Given the increasing likelihood that environmental chemicals will be found in wildlife habitat at 'acceptable levels', the critical role that wildlife nutrition plays in evaluating ecological risks should be fully integrated into the assessment process. Tools applied to the analysis of risk must gain higher resolution than the relatively crude methods we currently bring to the process.

Society of Environmental Toxicology and Chemistry,↗

USGS2016

Avian mercury exposure and toxicological risk across western North America: A synthesis

Methylmercury contamination of the environment is an important issue globally, and birds are useful bioindicators for mercury monitoring programs. The available data on mercury contamination of birds in western North America were synthesized. Original data from multiple databases were obtained and a literature review was conducted to obtain additional mercury concentrations. In total, 29219 original bird mercury concentrations from 225 species were compiled, and an additional 1712 mean mercury concentrations, representing 19998 individuals and 176 species, from 200 publications were obtained. To make mercury data comparable across bird tissues, published equations of tissue mercury correlations were used to convert all mercury concentrations into blood-equivalent mercury concentrations. Blood-equivalent mercury concentrations differed among species, foraging guilds, habitat types, locations, and ecoregions. Piscivores and carnivores exhibited the greatest mercury concentrations, whereas herbivores and granivores exhibited the lowest mercury concentrations. Bird mercury concentrations were greatest in ocean and salt marsh habitats and lowest in terrestrial habitats. Bird mercury concentrations were above toxicity benchmarks in many areas throughout western North America, and multiple hotspots were identified. Additionally, published toxicity benchmarks established in multiple tissues were summarized and translated into a common blood-equivalent mercury concentration. Overall, 66% of birds sampled in western North American exceeded a blood-equivalent mercury concentration of 0.2 μg/g wet weight (ww; above background levels), which is the lowest-observed effect level, 28% exceeded 1.0 μg/g ww (moderate risk), 8% exceeded 3.0 μg/g ww (high risk), and 4% exceeded 4.0 μg/g ww (severe risk). Mercury monitoring programs should sample bird tissues, such as adult blood and eggs, that are most-easily translated into tissues with well-developed toxicity benchmarks and that are directly relevant to bird reproduction. Results indicate that mercury contamination of birds is prevalent in many areas throughout western North America, and large-scale ecological attributes are important factors influencing bird mercury concentrations.

Science of the Total Environment↗

USGS1971

DDE thins eggshells and lowers reproductive success of captive black ducks

Eggs of captive black ducks fed diets containing DDE at 10 and 30 ppm (dry weight) experienced significant shell thinning and an increase in shell cracking when compared to eggs of untreated black ducks. Eggshells from dosed ducks were: 18-24 percent thinner at the equator than shells from undosed ducks; 28-31 percent thinner at the cap; and 29-38 percent thinner at the apex. Shell cracking averaged 21 percent among eggs fram the 30 ppm DDE dosage and 10 percent among eggs from the 10 ppm dosage. Only 2 percent of the eggs from untreated black ducks were cracked. Survival of ducklings fram dosed parents in terms of 'percentage of 21-day ducklings of embryonated eggs' was 40-76 percent lower than survival of ducklings from undosed parents. Average DDE residues (wet weight) in eggs from hens fed 10 and 30 ppm DDE were 46 ppm and 144 ppm, respectively.

Bulletin of Environmental Contamination and Toxico↗

USGS2009

Widespread occurrence of intersex in black basses (Micropterus spp.) from U.S. rivers, 1995-2004

Intersex occurrence in freshwater fishes was evaluated for nine river basins in the United States. Testicular oocytes (predominantly male testes containing female germ cells) were the most pervasive form of intersex observed, even though similar numbers of male (n = 1477) and female (n = 1633) fish were examined. Intersex was found in 3% of the fish collected. The intersex condition was observed in four of the 16 species examined (25%) and in fish from 34 of 111 sites (31%). Intersex was not found in multiple species from the same site but was most prevalent in largemouth bass (Micropterus salmoides; 18% of males) and smallmouth bass (M. dolomieu; 33% of males). The percentage of intersex fish per site was 8-91% for largemouth bass and 14-73% for smallmouth bass. The incidence of intersex was greatest in the southeastern United States, with intersex largemouth bass present at all sites in the Apalachicola, Savannah, and Pee Dee River Basins. Total mercury, trans-nonachlor, p,p???-DDE, p,p???-DDD, and total PCBs were the most commonly detected chemical contaminants at all sites, regardless of whether intersex was observed. Although the genotype of the intersex fish was not determined, the microscopic appearance of the gonads, the presence of mature sperm, and the concentrations of sex steroid hormones and vitellogenin indicate the intersex bass were males. Few reproductive endpoints differed significantly among male and intersex bass; plasma vitellogenin concentration in males was not a good indicator of intersex presence. Hierarchical linkages of the intersex condition to reproductive function will require a more quantitative measure of intersex (e.g. severity index) rather than presence or absence of the condition. The baseline incidence of intersex gonadal tissue in black basses and other freshwater fishes is unknown, but intersex prevalence may be related to collection season, age, and endocrine active compounds in the environment. Intersex was not found in largemouth bass older than five years and was most common in 1-3-year-old male largemouth bass. The cause(s) of intersex in these species is also unknown, and it remains to be determined whether the intersex we observed in largemouth and smallmouth bass developed during sex differentiation in early life stages, during exposure to environmental factors during adult life stages, or both.

Aquatic Toxicology↗

USGS1991

Effects of pesticides on songbird productivity in conjunction with pecan cultivation in southern Georgia: A multiple-exposure experimental design

A prototypic experimental design was used to assess sublethal effects of multiple and varied organophosphates and carbamates on reproduction in birds. The design allowed for classification of pesticide exposure according to toxicity of applied compounds and type and frequency of applications. Daily survival rates (DSRs) of nests, eggs, and nestlings were determined for northern mockingbirds (Mimus polyglottos) , brown thrashers (Toxostoma rufum) , and northern cardinals (Cardinalis cardinalis) nesting along edges of pecan orchards and row crops in southern Georgia. Egg and nestling DSRs for all species combined varied inversely ( P < 0.05) with exposure. Nestling weight gain was reduced ( P < 0.05) with increasing exposure levels in northern mockingbirds and brown thrashers. Parenting behavior in northern cardinal and northern mockingbird did not differ ( P > 0.05) among three exposure levels. Brain cholinesterase activities were age-dependent and substantiated adult, but not nestling, exposure. Results suggest that increasing exposure to pesticides may reduce songbird productivity.

Environmental Toxicology and Chemistry↗

USGS2024

Reduced freshwater mussel juvenile production as a result of agricultural and urban contaminant mixture exposures

Freshwater mussels provide invaluable ecological services but are threatened by habitat alteration, poor water quality, invasive species, climate change, and contaminants, including contaminants of emerging concern (CECs). Contaminants of emerging concerns are well documented in aquatic environments, including the Great Lakes Basin, but limited information is available on how environmentally relevant mixtures affect freshwater mussel biology throughout their varied life stages. Our main goal was to assess mussels' reproductive output in response to exposure to agricultural and urban CEC mixtures during glochidial development through juvenile transformation and excystment focusing on how exposure duration and treatment affect: (1) the number of glochidia prematurely released by brooding females, (2) glochidial transformation through host-fish excystment, and (3) the number of fully metamorphosed juveniles able to continue the lifecycle. Mussels and host fish were exposed to either a control water (CW), control ethanol (CE), agriculture CEC mixture (AM), or urban CEC mixture (UM) for 40 and 100 days. We found no effect from treatment or exposure duration on the number of glochidia prematurely released. Fewer partially and fully metamorphosed AM juveniles were observed during the 100-day exposure, compared with the 40-day. During the 40-day exposure, CW produced more fully metamorphosed individuals compared with CE and UM, but during the 100-day exposure AM produced more fully metamorphosed individuals compared with the CW. There was reduction in fully metamorphosed juveniles compared with partially metamorphosed for CE and UM during the 40-day exposure, as well as in the CW during the 100-day exposure. These results will be important for understanding how mussel populations are affected by CEC exposure. The experiments also yielded many insights for laboratory toxicology exposure studies.

Environmental Toxicology and Chemistry↗

USGS1991

Acute toxicity of four anticholinesterase insecticides to American kestrels, eastern screech-owls and northern bobwhites

American kestrels (Falco sparverius), eastern screech-owls (Otus asio), and northern bobwhites (Colinus virginianus) were given single acute oral doses of four widely diverse anticholinesterase pesticides: EPN, fenthion, carbofuran, and monocrotophos. LD50s, based on birds that died within 5 d of dosage, were computed for each chemical in each species. Sex differences in the sensitivity of northern bobwhites in reproductive condition were examined. American kestrels were highly sensitive to all chemicals tested (LD50s 0.6--4.0 mg/kg). Eastern screech-owls were highly tolerant to EPN (LD50 274 mg/kg) but sensitive to the remaining chemicals (LD50s 1.5-3.9 mg/kg). Northern bobwhites were highly sensitive to monocrotophos (LD50 0.8 mg/kg) and less sensitive to the remaining chemicals (LD50s 4.6--31 mg/kg). Female bobwhites (LD50 3.1 mg/kg) were more sensitive to fenthion than males (LD50 7.0 mg/kg). Mean percent depression of brain cho[inesterase (ChE) of birds that died on the day of dosing exceeded 65% for all chemicals in all species. The response of one species to a given pesticide should not be used to predict the sensitivity of other species to the same pesticide. The need for research on several topics is discussed

Environmental Toxicology and Chemistry↗

USGS2005

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

Response of the amphipod Hyalella azteca exposed to contaminated sediments for 10 to 42 d in laboratory toxicity tests was compared to responses observed in controlled three-month invertebrate colonization exposures conducted in a pond. Sediments evaluated included a sediment spiked with dichlorodiphenyldichloroethane (DDD) or dilutions of a field sediment collected from the Grand Calumet River (GCR) in Indiana (USA) (contaminated with organic compounds and metals). Consistent effects were observed at the highest exposure concentrations (400 ??g DDD/goc [DDD concentrations normalized to grams of organic carbon (goc) in sedimentl or 4% GCR sediment) on survival, length, and reproduction of amphipods in the laboratory and on abundance of invertebrates colonizing sediments in the field. Effect concentrations for DDD observed for 10-d length and 42-d reproduction of amphipods (e.g., chronic value [ChV] of 66 ??g DDD/goc and 25% inhibition concentration [IC25] of 68 ??g DDD/goc for reproduction) were similar to the lowest effect concentrations for DDD measured on invertebrates colonizing sediment the field. Effect concentrations for GCR sediment on 28-d survival and length and 42-d reproduction and length of amphipods (i.e., ChVs of 0.20-0.66% GCR sediment) provided more conservative effect concentrations compared to 10-d survival or length of amphipods in the laboratory or the response of invertebrates colonizing sediment in the field (e.g., ChVs of 2.2% GCR sediment). Results of this study indicate that use of chronic laboratory toxicity tests with H. azteca and benthic colonization studies should be used to provide conservative estimates of impacts on benthic communities exposed to contaminated sediments. Bioaccumulation of DDD by oligochaetes colonizing the DDD-spiked sediment was similar to results of laboratory sediment tests previously conducted with the oligochaete Lumbriculus variegates, confirming that laboratory exposures can be used to estimate bioaccumulation by oligochaetes exposed in the field. ?? 2005 SETAC.

Environmental Toxicology and Chemistry↗

USGS2025

Effects of dietary selenium on the amphipod Hyalella azteca and the midge Chironomus dilutus

Chronic selenium (Se) water quality criteria are based primarily on dietary organoselenium exposure and subsequent reproductive effects in fish. Available chronic Se toxicity data suggests that invertebrates are less sensitive than fish, but chronic invertebrate studies are limited. We evaluated yeast-based diets for chronic toxicity studies with Hyalella azteca and Chironomus dilutus. Growth and survival were similar among C. dilutus fed a yeast-only diet, a mixture of yeast and fish flake food, and a mixture of yeast and diatoms. Survival and growth of H. azteca were best in the yeast + diatom diet, so this diet was used for subsequent tests. In rangefinder tests, H. azteca 28-day survival, growth, and biomass, and C. dilutus 11-day survival were all significantly reduced at a dietary Se concentration of 49 µg/g dry weight, whereas C. dilutus growth and biomass were only affected at 200 µg/g dry weight Se. H. azteca had similar sensitivity to dietary Se in a 28–42-day chronic test—survival, growth, and biomass were significantly reduced at 44.5 µg/g dry weight Se. Dietary selenium reduced H. azteca reproduction by 75%–100% relative to Controls, but differences were not significant. Tissue Se EC10s were lower for H. azteca (9.0–23 µg/g dry weight) than for C. dilutus (11–56 µg/g dry weight). However, model evaluations suggest that the C. dilutus 11-day survival and H. azteca 42-day EC10s were less reliable than other endpoints. When tissue EC10s were converted to equivalent Se concentrations in fish tissue with a food web model, H. azteca (18 µg/g dry weight) and C . dilutus (68 µg/g dry weight) ranked 6th and 12th of 13 freshwater genera, respectively. Overall, these results suggest that the current U.S. Environmental Protection Agency tissue-based Se water quality criteria would be protective for fish and invertebrates and could be used for management of fishless waters.

Environmental Toxicology and Chemistry↗

USGS2008

Ethoxyresorufin-O-deethylase (EROD) activity in fish as a biomarker of chemical exposure

This review compiles and evaluates existing scientific information on the use, limitations, and procedural considerations for EROD activity (a catalytic measurement of cytochrome P4501A induction) as a biomarker in fish. A multitude of chemicals induce EROD activity in a variety of fish species, the most potent inducers being structural analogs of 2,3,7,8-tetracholordibenzo- p -dioxin. Although certain chemicals may inhibit EROD induction/activity, this interference is generally not a drawback to the use of EROD induction as a biomarker. The various methods of EROD analysis currently in use yield comparable results, particularly when data are expressed as relative rates of EROD activity. EROD induction in fish is well characterized, the most important modifying factors being fish species, reproductive status and age, all of which can be controlled through proper study design. Good candidate species for biomonitoring should have a wide range between basal and induced EROD activity (e.g., common carp, channel catfish, and mummichog). EROD activity has proven value as a biomarker in a number of field investigations of bleached kraft mill and industrial effluents, contaminated sediments, and chemical spills. Research on mechanisms of CYP1A-induced toxicity suggests that EROD activity may not only indicate chemical exposure, but also may also precede effects at various levels of biological organization. A current research need is the development of chemical exposure-response relationships for EROD activity in fish. In addition, routine reporting in the literature of EROD activity in standard positive and negative control material will enhance confidence in comparing results from different studies using this biomarker.

Critical Reviews in Toxicology↗

USGS1989

Contaminants in foods of aquatic birds at Kesterson Reservoir, California, 1985

Plants, aquatic insects, and mosquitofish ( Gambusia affinis ) were collected from Kesterson Reservoir, Merced County, California, and a nearby reference site (Volta Wildlife Area) to compare concentrations of three contaminants found in 1985 with those reported in 1983 and 1984. Mean selenium concentrations in food-chain organisms from sites at Kesterson in 1985 ranged from 26.0 μg/g (dry wt) in water boatman (Corixidae) to 119 μg/g in mosquitofish. All mean selenium concentrations at Kesterson were significantly higher than those from Volta and were sufficient to have caused the impaired avian reproduction observed at Kesterson. Boron concentrations were also significantly higher at Kesterson, and, at one pond, the mean concentration in widgeongrass ( Ruppia mari-tima ) (1,630 μg/g) was high enough to impair avian reproduction. There were no differences in arsenic concentrations between locations, and concentrations in all food-chain organisms (<1.9 μg/g) were lower than those reported to cause adverse effects in wildlife. Within-location differences were observed for all three contaminants at Kesterson and for selenium at Volta, but there was no consistent pattern to these differences. Between-year comparisons showed that selenium concentrations in mosquitofish generally decreased at Kesterson, but remained about the same at Volta over the 3 years. Selenium concentrations in insects from 1985 were lower at Kesterson than 1983, but were similar to 1984. Concentrations in plants were generally higher in 1983 and lower in 1984 compared with 1985. Boron concentrations in plants were generally higher in 1985, but in mosquitofish and insects, boron concentrations remained about the same all 3 years. Most arsenic concentrations did not change significantly between years.

California↗

USGS2019

Toxicity of aluminum to Ceriodaphnia dubia in low-hardness waters as affected by natural dissolved organic matter

We conducted a series of 7‐d toxicity tests with Ceriodaphnia dubia in dilutions of low‐hardness natural waters, which contained dissolved organic carbon (DOC) concentrations up to 10 mg/L. Stream waters were mixed with well water to achieve 2 target hardness levels (20 and 35 mg/L) and 4 DOC concentrations. Tests with aluminum (Al)‐spiked waters were conducted in a controlled CO 2 atmosphere to maintain the pH at a range of 6.0 to 6.5. The results were used to estimate effect concentrations for survival and reproduction, expressed as total (unfiltered) Al concentrations. There were small differences in total‐Al thresholds between waters with 20 and 35 mg/L hardness, but effect concentrations for C. dubia survival (median lethal concentrations) and reproduction (effect concentrations, 20%) increased log‐linearly with increasing DOC concentrations in the range, 0.3 to 6 mg/L. Slopes of these regressions were similar to slopes from data used to revise the US Environmental Protection Agency water quality criterion for Al, but toxic effects in the present study occurred at total‐Al concentrations 8‐ to 10‐fold greater than toxicity values used for criteria development. This difference probably reflects the long equilibration (aging) times of Al test waters used in the present study (up to 192 h) compared with short (3‐h) equilibration times in other studies used for criteria development. These results confirm the importance of DOC as a control on Al toxicity in low‐hardness waters, but they also demonstrate that total‐Al concentrations are not predictive of Al toxicity, except under defined water quality (pH, hardness, DOC) and exposure conditions (e.g., aging of test waters).

Environmental Toxicology and Chemistry↗

USGS2017

The effects of fipronil and the photodegradation product fipronil desulfinyl on growth and gene expression in juvenile blue crabs, Callinectes sapidus , at different salinities

Endocrine disrupting compounds (EDCs) are now widely established to be present in the environment at concentrations capable of affecting wild organisms. Although many studies have been conducted in fish, less is known about effects in invertebrates such as decapod crustaceans. Decapods are exposed to low concentrations of EDCs that may cause infertility, decreased growth, and developmental abnormalities. The objective herein was to evaluate effects of fipronil and its photodegradation product fipronil desulfinyl. Fipronil desulfinyl was detected in the eggs of the decapod Callinectes sapidus sampled off the coast of South Carolina. As such, to examine specific effects on C. sapidus exposed in early life, we exposed laboratory-reared juveniles to fipronil and fipronil desulfinyl for 96 hours at three nominal concentrations (0.01, 0.1, 0.5 μg/L) and two different salinities (10, 30 ppt) . The size of individual crabs (weight, carapace width) and the expression of several genes critical to growth and reproduction were evaluated. Exposure to fipronil and fipronil desulfinyl resulted in significant size increases in all treatments compared to controls. Levels of expression for vitellogenin (Vtg), an egg yolk precursor, and the ecdysone receptor (EcR), which binds to ecdysteroids that control molting, were inversely correlated with increasing fipronil and fipronil desulfinyl concentrations. Effects on overall growth and on the expression of EcR and Vtg differ depending on the exposure salinity. The solubility of fipronil is demonstrated to decrease considerably at higher salinities. This suggests that fipronil and its photodegradation products may be more bioavailable to benthic organisms as salinity increases, as more chemical would partition to tissues. Our findings suggest that endocrine disruption is occurring through alterations to gene expression in C. sapidus populations exposed to environmental levels of fipronil, and that effects may be dependent upon the salinity at which exposure occurs.

Aquatic Toxicology↗

USGS1989

Toxic effects of boron on mallard reproduction

Boron, a naturally occurring trace element generally considered environmentally innocuous, was documented to severely impair mallard reproduction. Boron is leached from irrigated agricultural soils and transported in drainage water that contaminates wetlands. Until now, only the selenium accumulated in aquatic food chains has been documented to pose a toxic hazard to wildlife in drainage water wetlands. Adult mallard ( Anas platyrhynchos ) ducks were fed diets supplemented with 0, 30, 300 or 1,000 ppm boron (fresh weight; diets contained about 10% moisture). The hatching success of fertile eggs was significantly reduced by 1,000 ppm boron, less than one-third the highest boron concentrations found in plants in California's San Joaquin Valley. Hatching weights, duckling survival and duckling weight gain were also reduced by 1,000 ppm boron. Boron concentrations in mallard egg, liver and brain tissues were dose-related. Boron did not affect adult survival or egg fertility. Management of drainage water-contaminated environments must now also consider the adverse effects of boron, as well as the possible interactions of drainage water contaminants.

Environmental Toxicology and Chemistry↗

USGS2002

Metal concentrations in zebra mussels and sediments from embayments and riverine environments of eastern Lake Erie, southern Lake Ontario, and the Niagara River

Concentrations of 14 metals were studied in the soft tissues of zebra mussels ( Dreissena polymorpha ) and sediments from 16 Great Lakes embayments and riverine environments. Samples were collected in 1993 and 1994 during the early and late autumn period when the body mass of mussels is least affected by reproductive activities. There was a significant difference in geometric mean concentrations of all metals except Cu in mussels sampled from different sites, and there was a significant difference in the geometric mean concentrations of all metals but Cd, Mn, and Zn between years. The higher metal concentrations in mussels from this study were generally similar to those in mussels from contaminated European and U.S. locations, and those with lower concentrations were similar to those from uncontaminated European and U.S. locations. Geometric mean sediment concentrations of all metals differed significantly among sites. Sediment concentrations of metals from some sites were above EPA guidelines for moderately polluted harbor sediments. Sites where zebra mussels had higher concentrations of Al, Cr, and V tended to be the same sites as those where sediment concentrations of these metals were also higher. However, there was not a significant statistical relationship between concentrations of metals in zebra mussels and sediments, except for Mg.

Lake Erie, Lake Ontario, Niagara River↗

USGS1995

Dietary exposure of mink to carp from Saginaw Bay, Michigan. 1. Effects on reproduction and survival, and the potential risks to wild mink populations

Carp ( Cyprinus carpio ) collected from Saginaw Bay, Michigan, containing 8.4 mg total polychlorinated biphenyls (PCBs)/kg and 194 ng of 2,3,7,8-tetrachloro-dibenzo- p -dioxin equivalents (TEQs)/kg, were substituted for marine fish at levels of 0, 10, 20, or 40% in the diets of adult ranch mink ( Mustela vison ). The diets, containing 0.015, 0.72, 1.53, and 2.56 mg PCBs/kg diet, or 1.03, 19.41, 40.02, and 80.76 ng TEQs/kg diet, respectively, were fed to mink prior to and throughout the reproductive period to evaluate the effects of a naturally-contaminated prey species on their survival and reproductive performance. The total quantities of PCBs ingested by the mink fed 0, 10, 20, or 40% carp over the 85-day treatment period were 0.34, 13.2, 25.3, and 32.3 mg PCBs/mink, respectively. The corresponding quantities of TEQs ingested by the mink over the same treatment period were 23, 356, 661, and 1,019 ng TEQs/mink, respectively. Consumption of feed by mink was inversely proportional to the PCB and TEQ content of the diet. The diets containing Saginaw Bay carp caused impaired reproduction and/or reduced survival of the kits. Compared to controls, body weights of kits at birth were significantly reduced in the 20 and 40% carp groups, and kit body weights and survival in the 10 and 20% carp groups were significantly reduced at three and six weeks of age. The females fed 40% carp whelped the fewest number of kits, all of which were stillborn or died within 24 hours. Lowest observable adverse effect levels (LOAEL) of 0.134 mg PCBs/kg body weight/day or 3.6 ng TEQs/kg body weight/day for adult female mink were determined. The potential effects of exposure of wild mink to contaminated Great Lakes fish were assessed by calculating “maximum allowable daily intakes” and “hazard indices” based on total concentrations of PCB residues in several species of Great Lakes fish and mink toxicity data derived from the study.

Archives of Environmental Contamination and Toxico↗