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At least 19 recordsLinked to original sources
USGS1994

Accumulation of 2,3,7,8-Tetrachlorodibenzo-p-dioxin equivalents by double-crested cormorant ( Phalacrocorax auritus , Pelicaniformes) chicks in the North American Great Lakes

Concentrations of polychlorinated biphenyls (PCBs), and 2,3,7,8-tetrachlordibenzo- p -dioxin equivalents (TCDD-EQ) were determined in eggs and chicks of double-crested cormorants (DCC) which were collected in 1989 from eight locations in the Laurentian Great Lakes. The mean biomagnification factor (BMF) from forage fish to eggs was found to be 31.3. Absolute and relative concentrations as well as rates of accumulation of total concentrations of PCBs and TCDD-EQ were measurable in all of the samples. The concentrations of both PCBs and TCDD-EQs decreased immediately upon hatching of chicks, due to growth dilution. Initial decreases in absolute masses of TCDD-EQ in chicks were also observed, which indicates that there can be significant elimination of these compounds during early development. The initial rates of accumulation by chicks were dependent only on the mass of fish consumed. After the chicks began thermoregulating, the rates of accumulation, expressed as a concentration, normalized to body weight, became greater. Rates of accumulation of both PCBs and TCDD-EQ were correlated with their respective concentrations in forage fish consumed by the chicks. The relative potency, expressed as the ratio of the concentration of TCDD-EQ to that of total PCBs was calculated to determine if there was significant trophic-level enrichment of the TCDD-EQs, relative to total concentrations of PCBs. A significant enrichment was observed at the more and less contaminated locations, but the degree of enrichment was greater at the less contaminated locations (26 vs 72 μg/g).

Ecotoxicology and Environmental Safety↗
USGS1995

Hazard assessment of inorganics to three endangered fish in the Green River, Utah

Acute toxicity tests were conducted with three life stages of Colorado squawfish ( Ptychocheilus lucius ), razorback sucker ( Xyrauchen texanus ), and bonytail ( Gila elegans ) in a reconstituted water quality simulating the middle part of the Green River of Utah. Tests were conducted with boron, lithium, selenate, selenite, uranium, vanadium, and zinc. The overall rank order of toxicity to all species and life stages combined from most to least toxic was vanadium = zinc > selenite > lithium = uranium > selenate > boron. There was no difference between the three species in their sensitivity to the seven inorganics based on a rank-order evaluation at the species level. Colorado squawfish were 2-5 times more sensitive to selenate and selenite at the swimup life stage than older stages, whereas razorback suckers displayed equal sensitivity among life stages. Bonytail exhibited equal sensitivity to selenite, but were five times more sensitive to selenate at the swimup life stage than the older stages. Comparison of 96-hr LC 50 values with a limited number of environmental water concentrations in Ashley Creek, Utah, which receives irrigation drainwater, revealed moderate hazard ratios for boron, selenate, selenite, and zinc, low hazard ratios for uranium and vanadium, but unknown ratios for lithium. These inorganic contaminants in drainwaters may adversely affect endangered fish in the Green River.

Utah↗
USGS1996

Acute toxicity of fire control chemicals to Daphnia magna (Straus) and Selenastrum capricornutum (Printz)

Acute toxicity tests were conducted exposing Daphnia magna Straus (daphnid) in soft and hard reconstituted waters (hardness 42 and 162 mg/liter as CaCO 3 , respectively), and Selenastrum capricornutum Printz (algae) in ASTM algal assay medium (hardness 15 mg/liter as CaCO 3 ) to fire retardants Fire-Trol GTS-R, Fire-Trol LCG-R, and Phos-Chek D75-F, and foam suppressants Phos-Chek WD-881 and Silv-Ex. The chemicals were slightly toxic to practically harmless to daphnids and moderately toxic to algae. Water quality did not consistently alter the toxicity of the test chemicals to daphnids. The most toxic chemical to daphnids was Silv-Ex (48-hr EC 50 7 mg/liter in soft and hard waters), whereas the least toxic chemical to daphnids was Fire-Trol LCG-R (48-hr EC 50 848 mg/liter in soft water, 813 mg/liter in hard water). The most toxic chemical to algae was Fire-Trol LCG-R (96-hr IC 50 10 mg/liter), and the least toxic chemical was Phos-Chek D75-F (96-hr IC 50 79 mg/liter). Un-ionized ammonia concentrations near the EC 50 or IC 50 value in tests with the Fire-Trol compounds were frequently equal to or above reported LC 50 un-ionized ammonia concentrations. Un-ionized ammonia concentrations in tests with Phos-Chek D75-F were low, thus other toxic components present in the compounds probably contributed to the toxicity. When compared to the daphnids tested in ASTM soft water, the Fire-Trol compounds were most toxic to algae, whereas Phos-Chek D75-F and the foam suppressants were most toxic to daphnids. The results of these tests are comparable to those obtained from research conducted in other laboratories with the same species and similar chemicals. Accidental entry of fire-fighting chemicals into aquatic environments could adversely affect algae and aquatic invertebrates, thus disrupting ecosystem function.

Ecotoxicology and Environmental Safety↗
USGS1996

Acute toxicity of firefighting chemical formulations to four life stages of fathead minnow

Laboratory studies were conducted with four early life stages of fathead minnow,Pimephales promelas,to determine the acute toxicity of five firefighting chemical formulations in standardized soft and hard water. Egg, fry, 30-day posthatch, and 60-day posthatch life stages were tested with three fire retardants (Fire-Trol GTS-R, Fire-Trol LCG-R, and Phos-Chek D75-F) and two fire-suppressant foams (Phos-Chek WD-881 and Ansul Silv-Ex). Fry were generally the most sensitive life stage tested, whereas the eggs were the least sensitive life stage. Formulation toxicity was greater in hard water than in soft water for all life stages tested. Fire-suppressant foams were more toxic than the fire retardants. The 96-hr LC50s derived for fathead minnows were rank ordered from the most toxic to the least toxic formulation as follows: Phos-Chek WD-881 (13a??32 mg/liter) > Silv-Ex (19a??32 mg/liter) > Fire-Trol GTS-R (135a??787 mg/liter) > Phos-Chek D75-F (168a??2250 mg/liter) > Fire-Trol LCG-R (519a??6705 mg/liter) (ranges are the lowest and highest 96-hr LC50for each formulation). (C) 1996 Academic Press, Inc.

Ecotoxicology and Environmental Safety↗
USGS1996

Selenium bioaccumulation and hazards in a fish community affected by coal fly ash effluent

Bioaccumulation of selenium (Se) in the fish community of Pigeon River/Pigeon Lake, which receives inputs of Se from a coal fly ash disposal facility, was studied to assess potential hazards of Se to fish, wildlife, and humans. Se concentrations in fish from sites receiving seepage and effluents from fly ash disposal ponds were significantly greater than those in fish from upstream, where Se concentrations were near background concentrations. Se concentrations differed among fish species, and interspecific variation was greatest at the most contaminated locations. Differences in Se bioaccumulation among fish species were not consistently associated with differences in trophic status. Although Se concentrations in northern pike were consistently less than those in likely prey species, large yellow perch contained Se concentrations as great as those in spottail shiners, their likely prey. Se bioaccumulation may have been influenced by differences in habitat preferences, as limnetic species generally contained greater Se concentrations than benthic species. Se concentrations in fish from the lower Pigeon River and Pigeon Lake did not exceed lowest observable adverse effect concentrations (LOAECs) for Se in tissues of fish species, but exceeded LOAECs for dietary Se exposure of sensitive species of birds and mammals. Human consumption of moderate quantities of fish from the areas studied should not result in excessive Se intake.

Michigan↗
USGS1997

Relative sensitivity of three endangered fishes, Colorado squawfish, bonytail, and razorback sucker, to selected metal pollutants

The acute toxicity of four metal pollutants to larval and juvenile stages of endangered Colorado squawfish ( Ptychocheilus lucius ), bonytail ( Gila elegans ), and razorback sucker ( Xyrauchen texanus ) were determined in a water quality representative of that in the Green River, Utah. The rank order of toxicity (96-hr LC 50 ) of the metals to all species and life stages from most toxic to least toxic was mercury (57–168 μg/liter) > cadmium (78–168 μg/liter) > hexavalent chromium (32,000–123,000 μg/liter) > lead (>170,000 μg/liter). In tests with lead, a precipitate formed in all test solutions and no mortalities occurred in these treatments. The larvae of each species were as sensitive or more sensitive than the juveniles to cadmium, hexavalent chromium, and mercury. Overall, the three species exhibited similar sensitivities to cadmium, hexavalent chromium, and mercury. Comparison of test results for the juveniles with toxicity values reported for other freshwater fishes tested in different water qualities indicates that the endangered fishes are more sensitive to cadmium than other cyprinids and centrarchids and less sensitive than salmonids, whereas their sensitivity to hexavalent chromium and mercury is similar to that of other cyprinids, centrarchids, and salmonids.

Ecotoxicology and Environmental Safety↗
USGS1997

Hazard evaluation of inorganics, singly and in mixtures, to Flannelmouth Sucker Catostomus latipinnis in the San Juan River, New Mexico

Larval flannelmouth sucker ( Catostomus latipinnis ) were exposed to arsenate, boron, copper, molybdenum, selenate, selenite, uranium, vanadium, and zinc singly, and to five mixtures of five to nine inorganics. The exposures were conducted in reconstituted water representative of the San Juan River near Shiprock, New Mexico. The mixtures simulated environmental ratios reported for sites along the San Juan River (San Juan River backwater, Fruitland marsh, Hogback East Drain, Mancos River, and McElmo Creek). The rank order of the individual inorganics, from most to least toxic, was: copper > zinc > vanadium > selenite > selenate > arsenate > uranium > boron > molybdenum. All five mixtures exhibited additive toxicity to flannelmouth sucker. In a limited number of tests, 44-day-old and 13-day-old larvae exhibited no difference in sensitivity to three mixtures. Copper was the major toxic component in four mixtures (San Juan backwater, Hogback East Drain, Mancos River, and McElmo Creek), whereas zinc was the major toxic component in the Fruitland marsh mixture, which did not contain copper. The Hogback East Drain was the most toxic mixture tested. Comparison of 96-h LC 50 values with reported environmental water concentrations from the San Juan River revealed low hazard ratios for arsenic, boron, molybdenum, selenate, selenite, uranium, and vanadium, moderate hazard ratios for zinc and the Fruitland marsh mixture, and high hazard ratios for copper at three sites and four environmental mixtures representing a San Juan backwater, Hogback East Drain, Mancos River, and McElmo Creek. The high hazard ratios suggest that inorganic contaminants could adversely affect larval flannelmouth sucker in the San Juan River at four sites receiving elevated inorganics.

Ecotoxicology and Environmental Safety↗
USGS1999

Water-sediment controversy in setting environmental standards for selenium

A substantial amount of laboratory and field research on selenium effects to biota has been accomplished since the national water quality criterion was published for selenium in 1987. Many articles have documented adverse effects on biota at concentrations below the current chronic criterion of 5 μg/L. This commentary will present information to support a national water quality criterion for selenium of 2 μg/L, based on a wide array of support from federal, state, university, and international sources. Recently, two articles have argued for a sediment-based criterion and presented a model for deriving site-specific criteria. In one example, they calculate a criterion of 31 μg/L for a stream with a low sediment selenium toxicity threshold and low site-specific sediment total organic carbon content, which is substantially higher than the national criterion of 5 μg/L. Their basic premise for proposing a sediment-based method has been critically reviewed and problems in their approach are discussed.

Ecotoxicology and Environmental Safety↗
USGS2000

Hazard assessment of selenium and other trace elements in wild larval razorback sucker from the Green River, Utah

Contaminant investigations of the Green River in northeastern Utah have documented selenium contamination at sites receiving irrigation drainage. The Green River provides critical habitat for four endangered fishes including the largest extant riverine population of endangered razorback sucker. Although 2175 larval razorback suckers were collected from the river between 1992 and 1996, very few juveniles have been captured within recent decades. Selenium concentrations were measured in larval razorback suckers collected from five sites in the Green River (Cliff Creek, Stewart Lake Drain, Sportsman's Drain, Greasewood Corral, and Old Charlie Wash) to assess the potential for adverse effects on recruitment of larvae to the juvenile stage and the adult population. Larvae from all sites contained mean selenium concentrations ranging from 4.3 to 5.8 ??g/g. These values were at or above the proposed toxic threshold of 4 ??g/g for adverse biological effects in fish, which was derived from several laboratory and field studies with a wide range of fish species. At two sites, Cliff Creek and Stewart Lake Drain, selenium concentrations in larvae increased over time as fish grew, whereas selenium concentrations decreased as fish grew at Sportsman's Drain. Evaluation of a 279-larvae composite analyzed for 61 elements demonstrated that selenium and, to a lesser extent, vanadium were elevated to concentrations reported to be toxic to a wide range of fish species. Elevated selenium concentrations in larval razorback suckers from the five sites suggest that selenium contamination may be widespread in the Green River, and that survival and recruitment of larvae to the juvenile stage may be limited due to adverse biological effects. Selenium contamination may be adversely affecting the reproductive success and recruitment of endangered razorback sucker.

Ecotoxicology and Environmental Safety↗
USGS2001

Cholinergic and behavioral neurotoxicity of carbaryl and cadmium to larval rainbow trout ( Oncorhynchus mykiss )

Pesticides and heavy metals are common environmental contaminants that can cause neurotoxicity to aquatic organisms, impairing reproduction and survival. Neurotoxic effects of cadmium and carbaryl exposures were estimated in larval rainbow trout (RBT; Oncorhynchus mykiss ) using changes in physiological endpoints and correlations with behavioral responses. Following exposures, RBT were videotaped to assess swimming speed. Brain tissue was used to measure cholinesterase (ChE) activity, muscarinic cholinergic receptor (MChR) number, and MChR affinity. ChE activity decreased with increasing concentrations of carbaryl but not of cadmium. MChR were not affected by exposure to either carbaryl or cadmium. Swimming speed correlated with ChE activity in carbaryl-exposed RBT, but no correlation occurred in cadmium-exposed fish. Thus, carbaryl exposure resulted in neurotoxicity reflected by changes in physiological and behavioral parameters measured, while cadmium exposure did not. Correlations between behavior and physiology provide a useful assessment of neurotoxicity.

Ecotoxicology and Environmental Safety↗
USGS2001

Acetylcholinesterase inhibition in the threeridge mussel (Amblema plicata) by chlorpyrifos: Implications for biomonitoring

The effects of chlorpyrifos, an organophosphorus insecticide, were examined on the activity of the nervous system enzyme acetylcholinesterase (AChE) in the threeridge mussel Amblema plicata in a 24-day laboratory test. Thirty-six mussels in each of seven treatments (18 mussels per duplicate) were exposed to chlorpyrifos (0.1, 0.2, 0.3, 0.6, and 1.2 mg/L), a solvent (acetone), and a solvent-free (well water) control for 12, 24, or 96 h. The activity of AChE was measured in the anterior adductor muscle of eight mussels from each treatment after exposure. To assess potential latent effects, six mussels from each treatment were removed after 24 h of exposure and transferred to untreated water for a 21-day holding period; AChE activity was measured on three mussels from each treatment at 7 and 21 days of the holding period. The activity of AChE in chlorpyrifos-exposed mussels did not differ from controls after 12 or 24 h of exposure ( t - test, P >0.05), but was significantly less than controls after 96 h ( t - test, P =0.01). AChE activity did not vary among mussels at 24 h of exposure (i.e., Day 0 of holding period) and those at Day 7 and Day 21 of the holding period. Overall changes in AChE activity of mussels during the test were unrelated to individual chlorpyrifos concentrations and exposure times (repeated measure ANOVA; ( P =0.06). A power analysis revealed that the sample size must be increased from 2 to 5 replicates (8 to 20 mussels per time interval and test concentration) to increase the probability of detecting significant differences in AChE activity. This calculated increase in sample size has potential implications for future biomonitoring studies with chlorpyrifos and unionid mussels.

Minnesota↗
USGS2001

Assessment of selenium effects in lotic ecosystems

The selenium literature has grown substantially in recent years to encompass new information in a variety of areas. Correspondingly, several different approaches to establishing a new water quality criterion for selenium have been proposed since establishment of the national water quality criterion in 1987. Diverging viewpoints and interpretations of the selenium literature have lead to opposing perspectives on issues such as establishing a national criterion based on a sediment-based model, using hydrologic units to set criteria for stream reaches, and applying lentic-derived effects to lotic environments. This Commentary presents information on the lotic verse lentic controversy. Recently, an article was published that concluded that no adverse effects were occurring in a cutthroat trout population in a coldwater river with elevated selenium concentrations (C. J. Kennedy, L. E. McDonald, R. Loveridge, and M. M. Strosher, 2000, Arch. Environ. Contam. Toxicol. 39, 46–52). This article has added to the controversy rather than provided further insight into selenium toxicology. Information, or rather missing information, in the article has been critically reviewed and problems in the interpretations are discussed.

Ecotoxicology and Environmental Safety↗
USGS2002

Effects of a coastal golf complex on water quality, periphyton, and seagrass

The objective of this study was to provide baseline information on the effects of a golf course complex on water quality, colonized periphyton, and seagrass meadows in adjacent freshwater, near-coastal, and wetland areas. The chemical and biological impacts of the recreational facility, which uses reclaimed municipal wastewater for irrigation, were limited usually to near-field areas and decreased seaward during the 2-year study. Concentrations of chromium, copper, and organochlorine pesticides were below detection in surface water, whereas mercury, lead, arsenic, and atrazine commonly occurred at all locations. Only mercury and lead exceeded water quality criteria. Concentrations of nutrients and chlorophyll a were greater in fairway ponds and some adjacent coastal areas relative to reference locations and Florida estuaries. Periphyton ash free dry weight and pigment concentrations statistically differed but not between reference and non-reference coastal areas. Biomass of Thalassia testudinum (turtle grass) was approximately 43% less in a meadow located adjacent to the golf complex (P < 0.05). The results of the study suggest that the effects of coastal golf courses on water quality may be primarily localized and limited to peripheral near-coastal areas. However, this preliminary conclusion needs additional supporting data. ?? 2002 Elsevier Science (USA).

Florida↗
USGS1984

Toxicity of anticholinesterase insecticides to birds: Technical grade versus granular formulations

The acute toxicities of 13 granular anticholinesterase insecticides were compared with their technical grade active ingredients by administering single oral doses of chemical to adult Northern bobwhites (Colinus virginianus) and evaluating resultant LD50 values and dose-response curves. Similar tests with ringed turtledoves (Streptopelia risoria) were conducted with five of the granular formulations to check for interspecific differences. The test chemicals were Amaze 15G (isofenphos), Counter 15G (terbufos), Dasanit 15G (fensulfothion), Diazinon 14G (diazinon), Di-Syston 15G (disulfoton), Dyfonate 20G (fonofos), Furadan 10G (carbofuran), Lorsban 15G (chlorpyrifos), Nemacur 15G (fenamiphos), Parathion 10G (parathion), Tattoo 10G (bendiocarb), Temik 15G (aldicarb), and Thimet 15G (phorate). Information is also presented on dose-response relations and their use in hazard assessment, granule size and hazard, response patterns, and toxic signs. The general conclusions were: (1) The organophosphates (fenamiphos and fensulfothion) and the carbamate (aldicarb) were the most toxic of the insecticides tested. (2) The granular formulation and its technical grade active ingredient were of equivalent toxicity, or the granular was significantly less toxic. (3) The dose-response curve enhances hazard assessment. (4) Ingestion of a single granule of Temik 15G was shown to be life threatening to bobwhite-sized birds, and ingestion of fewer than five granules could be lethal to sparrow-sized birds for Dasanit 15G, Diazinon 14G, Dyfonate 20G, Furadan 15G, and Nemacur 15G. (5) It is therefore suggested that the hazard associated with granular insecticides may be more dependent on which species (cf. size and feeding behavior) inhabit a treated area than on the actual application rate.

Ecotoxicology and Environmental Safety↗
USGS1990

Comparative toxicity of inorganic contaminants released by placer mining to early life stages of salmonids

The acute toxicities of four trace inorganics associated with placer mining were determined, individually and in environmentally relevant mixtures, to early life stages of Arctic grayling ( Thymallus arcticus ) from Alaska and Montana, coho salmon ( Oncorhynchus kitsutch ) from Alaska and Washington, and rainbow trout ( Oncorhynchus mykiss ) from Montana. The descending rank order of toxicity to all species and life stages was copper > zinc > lead > arsenic. For each of the three species, sensitivity to the inorganics was greater in juveniles than in alvenins or in swim-up fry. Arctic grayling from Alaska were more sensitive than the other species tested, including Arctic grayling from Montana. For Arctic grayling, sensitivity to all four inorganics was significantly greater in swim-up fry from Alaska than in alevins from Montana, and sensitivity to arsenic and copper was significantly greater in juveniles from Alaska than in juveniles from Montana. In tests with environmentally relevant mixtures (based on ratios of concentrations measured in streams with placer mining) of these four inorganics, copper was identified as the major toxic component because it accounted for ⩾97% of the summed toxic units of the mixture, and an equitoxic mixture of these inorganics showed less-than-additive toxicity. Total and total recoverable copper concentrations reported in five Alaskan streams with active placer mines were higher than the acutely toxic concentrations, either individually or in mixtures, that the authors found to be acutely toxic to Arctic grayling and coho salmon from Alaska. However, caution should be used when comparing our results obtained in “clear” water to field situations, because speciation and toxicity of these inorganics may be altered in the presence of sediments suspended by placer mining activities.

Ecotoxicology and Environmental Safety↗
USGS2004

Reproductive and biochemical biomarkers in largemouth bass sampled downstream of a pulp and paper mill in Florida

The objective of this study was to evaluate the effects of bleached/unbleached kraft mill effluents (B/UKME) on the reproductive parameters of free-ranging Florida largemouth bass (Micropterus salmoides floridanus). The reproductive parameters measured included gonadosomatic index (GSI), histological evaluation of gonads, and plasma concentrations of vitellogenin (VTG), 17??-estradiol, and 11-ketotestosterone (11-KT). Hepatic ethoxyresorufin-O-deethylase (EROD) activity was measured as a marker of exposure to cytochrome P450-inducing agents in these effluents. Endpoints were compared among adult bass sampled from tributary and mainstream effluent-contaminated and reference sites. Females sampled from the site closest to the mill outfall had a significant five-fold increase in EROD activity compared to bass sampled from reference streams. Although sex hormones were significantly reduced in bass from exposed sites, there were no differences in VTG and GSI across sites. The absence of organism-level responses was probably not related to a lack of sensitivity, as previous studies in our laboratory have shown that bass exposed to these effluents exhibit changes in GSI and in other measures associated with reproductive success. In females, inverse relationships were observed between VTG and GSI and EROD activity. These relationship, however, were not consistent within all of the sites studied. Collectively, our findings indicate that hepatic EROD induction is an effective marker of B/UKME exposure in largemouth bass and that it might be associated with antiestrogenic effects in this species. ?? 2003 Elsevier Inc. All rights reserved.

Ecotoxicology and Environmental Safety↗
USGS2005

Selenium impacts on razorback sucker, Colorado River, Colorado: I. Adults

Adult razorback sucker ( Xyrauchen texanus ) were exposed to various selenium concentrations in ponds and isolated river channels of the Colorado River near Grand Junction, CO, to determine effects on their growth and residue accumulation over an 11-month period. Adults at Horsethief ponds were fed a commercial diet, whereas fish at Adobe Creek channel and North Pond foraged on natural food items. Selenium concentrations at Horsethief were 2.2 μg/L in water, 0.1–1.4 μg/g in sediment, and 2.3–3.1 μg/g in food organisms (1.1 μg/g in commercial fish food), at Adobe Creek were 3.8 μg/L in water, 0.5–2.1 μg/g in sediment, and 4–56 μg/g in food organisms, and at North Pond were 9.5 μg/L in water, 7–55 μg/g in sediment, and 20–81 μg/g in food organisms. The selenium concentrations in muscle plugs from adults at Adobe Creek (11.7 μg/g, SD=0.4, n=6 ) and North Pond (16.6 μg/g, SD=1.0, n=6 ) were greater than at Horsethief (4.5 μg/g, SD=0.2, n=6 ). During a depuration period adults from Adobe Creek and North Pond lost 1–2% of their selenium burden in 32 days and 14–19% in 66 days. Selenium accumulated in razorback sucker above toxic thresholds reported in other studies, yet those residues were less than those reported in muscle plugs of 40% of wild razorback sucker caught in the Green River, Utah.

Ecotoxicology and Environmental Safety↗
USGS2005

Selenium impacts on razorback sucker, Colorado River, Colorado: II. Eggs

Effects on hatching and development of fertilized eggs in adult razorback sucker ( Xyrauchen texanus ) exposed to selenium in flooded bottomland sites near Grand Junction, Colorado, were determined. After 9 months exposure, fish were collected and induced to spawn and eggs collected for inorganic element analyses. A 9-day egg study was conducted with five spawns from Horsethief ponds, six spawns from Adobe Creek channel, and four spawns from North Pond using a reference water and site waters. Selenium concentrations in eggs were 6.5 μg/g from Horsethief, 46 μg/g from Adobe Creek, 38 μg/g from North Pond, and 6.0 μg/g from brood stock. Eggs from young adults had a smaller diameter and higher moisture content than brood stock. There were no differences among the four sources in viability, survival, hatch, hatchability, or mortality of deformed embryos or larvae. Adobe Creek larvae had more deformed embryos in eggs held in site water than held in reference water. There were significant negative correlations between selenium concentrations in adult muscle plugs and percent hatch, egg diameter, and deformities in embryos. Results from this study suggest that selenium contamination in parts of the upper basin of the Colorado River should be a major concern to recovery efforts for endangered fish.

Ecotoxicology and Environmental Safety↗