Larval Fathead Minnows Research Articles

Response to Comment on “Effect of Methyl tert-Butyl Ether on the Bioconcentration and Photoinduced Toxicity of Fluoranthene in Fathead Minnow Larvae (Pimephales promelas)”

ADVERTISEMENT RETURN TO ISSUEPREVCorrespondence/Rebut...Correspondence/RebuttalNEXTResponse to Comment on “Effect of Methyl tert-Butyl Ether on the Bioconcentration and Photoinduced Toxicity of Fluoranthene in Fathead Minnow Larvae (Pimephalespromelas)”Eun-Ah Cho, James T. Oris, and A. John BailerView Author Information Department of Zoology Center for Environmental Toxicology and Statistics Miami University Oxford, Ohio 45056 Department of Mathematics & Statistics Center for Environmental Toxicology and Statistics Miami University Oxford, Ohio 45056Cite this: Environ. Sci. Technol. 2003, 37, 19, 4524–4525Publication Date (Web):August 22, 2003Publication History Published online22 August 2003Published inissue 1 October 2003https://doi.org/10.1021/es030491yCopyright © 2003 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views136Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (24 KB) Get e-AlertsSUBJECTS:Dissolved organic matter,Free radicals,Quantum efficiency,Radiation,Toxicity Get e-Alerts

Possible use of constructed wetland to remove selenocyanate, arsenic, and boron from electric utility wastewater

Wetland microcosms were used to evaluate the ability of constructed wetlands to remove extremely high concentrations of selenocyanate (SeCN −), arsenic (As), and boron (B) from wastewater generated by a coal gasification plant in Indiana. The wetland microcosms significantly reduced the concentrations of selenium (Se), As, B, and cyanide (CN) in the wastewater by 64%, 47%, 31%, and 30%, respectively. In terms of the mass of each contaminant, 79%, 67%, 57%, and 54% of the Se, As, B, and CN, respectively, loaded into the microcosms were removed from the wastewater. The primary sink for the retention of contaminants within the microcosms was the sediment, which accounted for 63%, 51%, and 36% of the Se, As, and B, respectively. Accumulation in plant tissues accounted for only 2–4%, while 3% of the Se was removed by biological volatilization to the atmosphere. Of the 14 plant species tested, cattail, Thalia, and rabbitfoot grass were highly tolerant of the contaminants and exhibited no growth retardation. Environmental toxicity testing with fathead minnow ( Pimephales promelas) larvae confirmed that the water treated by the wetland microcosms was less toxic than untreated water. The data from the wetland microcosms support the view that constructed wetlands could be used to successfully reduce the toxicity of aqueous effluent contaminated with extremely high concentrations of SeCN −, As, and B, and that a pilot-scale wetland should therefore be constructed to test this in the field. Cattail, Thalia, and rabbitfoot grass would be suitable plant species to establish in such wetlands.

Effect of Methyl tert-Butyl Ether on the Bioconcentration and Photoinduced Toxicity of Fluoranthene in Fathead Minnow Larvae (Pimephales promelas)

The use of methyl tert-butyl ether (MTBE) in reformulated gasoline in motorized watercraft can lead to the presence of both unburned MTBE and fossil fuel combustion products in aquatic environments. MTBE has been added to unleaded gasoline to decrease vehicular carbon monoxide emissions in the atmosphere since the 1980s. Fluoranthene is among the most prevalent polycyclic aromatic hydrocarbons (PAHs) identified in the exhaust of internal combustion engines, and it has toxic effects on organisms in the presence of near-ultraviolet radiation. Because the interactions between MTBE and PAHs were not known, the toxicities of MTBE and fluoranthene together in fish were studied. Four-day-old fathead minnow larvae were exposed to combinations of fluoranthene and MTBE in a laboratory system under simulated sunlight for 96 h. Fish exposed to both MTBE and fluoranthene experienced higher mortality as compared to fish exposed only to fluoranthene. Fish exposed to MTBE alone did not exhibit increased mortality as compared to no-exposure controls. Co-exposure to MTBE was associated with significantly increased uptake rates and significantly decreased elimination rates for fluoranthene. The bioconcentration factor in fish exposed to 20 μg of fluoranthene/L in the presence of 40 μg of MTBE/L was 1.7−2.2 times higher than that for fluoranthene alone. The observed pattern of mortality reflected the different body residues of fluoranthene in fish. We conclude that, because of enhanced bioconcentration factors, the photoinduced toxicity of fluoranthene and potentially other PAHs will be greater in aquatic environments where reformulated gasoline containing MTBE is utilized in motorized watercraft.

Studies on bioremediation of polycyclic aromatic hydrocarbon‐contaminated sediments: Bioavailability, biodegradability, and toxicity issues

The widespread contamination by polycyclic aromatic hydrocarbons (PAHs) has created a need for cost-effective bioremediation processes. This research studied a chronically PAH-contaminated estuarine sediment from the East River (ER; NY, USA) characterized by high concentrations of PAHs (approximately 4-190 ppm), sulfide, and metals and a marine sediment from New York/ New Jersey Harbor (NY/NJH; USA) with only trace quantities of PAHs (0.1-0.6 ppm). The focus was to examine the relationship between bioavailability of PAHs and their biological removal in a slurry system. Freshwater and marine sediment toxicity tests were conducted to measure baseline toxicity of both sediments to amphipods, aquatic worms, fathead and sheepshead minnow larvae, and a vascular plant; to determine the cause of toxicity; and to evaluate the effectiveness of the biotreatment strategies in reducing toxicity. Results showed the ER sediment was acutely toxic to all freshwater and marine organisms tested and that the toxicity was mainly caused by sulfide, PAHs, and metals present in the sediment. In spite of the high toxicity, most of the PAH compounds showed significant degradation in the aerobic sediment/water slurry system if the initial high oxygen demand due to the high sulfide content of the sediment was overcome. The removal of PAHs by biodegradation was closely related to their desorbed amount in 90% isopropanol solution during 24 h of contact, while the desorption of model PAH compounds from freshly spiked NY/NJH sediment did not describe the bioavailability of PAHs in the East River sediment well. The research improves our understanding of bioavailability as a controlling factor in bioremediation of PAHs and the potential of aerobic biodegradation for PAH removal and ecotoxicity reduction.

Joint acute toxicity of esfenvalerate and diazinon to larval fathead minnows (Pimephales promelas)

California (USA) agriculture employs pyrethroid and organophosphate insecticides to control insects in orchards and other crops. Diazinon and esfenvalerate were selected for this study because of their application overlaps. Toxicological and biochemical responses of larval fathead minnows (Pimephales promelas) exposed singly and in combinations to esfenvalerate and diazinon were determined. Exposures were 96-h static renewal tests that used standard U.S. Environmental Protection Agency acute toxicity test methods. After pesticide exposures, larvae were evaluated for carboxylesterase and acetylcholinesterase activity, and histopathological effects. Carboxylesterase activity was examined because of its potential influence on the toxicity of both organophosphates and pyrethroids. In vivo studies demonstrated that diazinon significantly inhibited carboxylesterase activity at nominal water concentrations as low as 50 microg/L. However, esfenvalerate did not affect carboxylesterase activity at any concentration tested. Liver glycogen depletion was the only histopathological effect observed; this effect was demonstrated with the individual pesticides and pesticide combinations (i.e., mixtures). The combinations of diazinon and esfenvalerate causing acute toxicity to fathead minnow larvae appeared to be greater than additive (i.e., synergistic) in all three tests.

STUDIES ON BIOREMEDIATION OF POLYCYCLIC AROMATIC HYDROCARBON-CONTAMINATED SEDIMENTS: BIOAVAILABILITY, BIODEGRADABILITY, AND TOXICITY ISSUES

The widespread contamination by polycyclic aromatic hydrocarbons (PAHs) has created a need for cost-effective bioremediation processes. This research studied a chronically PAH-contaminated estuarine sediment from the East River (ER; NY, USA) characterized by high concentrations of PAHs (∼4–190 ppm), sulfide, and metals and a marine sediment from New York/New Jersey Harbor (NY/NJH; USA) with only trace quantities of PAHs (0.1–0.6 ppm). The focus was to examine the relationship between bioavailability of PAHs and their biological removal in a slurry system. Freshwater and marine sediment toxicity tests were conducted to measure baseline toxicity of both sediments to amphipods, aquatic worms, fathead and sheepshead minnow larvae, and a vascular plant; to determine the cause of toxicity; and to evaluate the effectiveness of the biotreatment strategies in reducing toxicity. Results showed the ER sediment was acutely toxic to all freshwater and marine organisms tested and that the toxicity was mainly caused by sulfide, PAHs, and metals present in the sediment. In spite of the high toxicity, most of the PAH compounds showed significant degradation in the aerobic sediment/water slurry system if the initial high oxygen demand due to the high sulfide content of the sediment was overcome. The removal of PAHs by biodegradation was closely related to their desorbed amount in 90% isopropanol solution during 24 h of contact, while the desorption of model PAH compounds from freshly spiked NY/NJH sediment did not describe the bioavailability of PAHs in the East River sediment well. The research improves our understanding of bioavailability as a controlling factor in bioremediation of PAHs and the potential of aerobic biodegradation for PAH removal and ecotoxicity reduction.

Zebra mussels (Dreissena polymorpha) limit food for larval fish (Pimephales promelas) in turbulent systems: a bioenergetics analysis*

We conducted a factorial experiment, in outdoor mesocosms, on the effects of zebra mussels and water column mixing (i.e., turbulence) on the diet, growth, and survival of larval fathead minnows (Pimephales promelas). Significant (P< 0.05) larval mortality occurred by the end of the experiment with the highest mortality (90%) occurring in the presence of both turbulence and zebra mussels, whereas mortality was 37% in treatment with turbulence and 17% and 18% in the zebra mussels treatment, and the control, respectively. The size of individual fish was significantly different among treatments at the end of the experiment and was inversely related to survival. Levels of trophic resources (i.e., phyto and zooplankton) varied among treatments and were treatment specific. Turbulent mixing facilitated removal of phytoplankton by zebra mussels by making the entire water column of the tanks available to these benthic filter feeders. Early in the experiment (Day = 0 to 14) the physical process of turbulent mixing likely caused a reduction in standing stocks of zooplankton. The interactive effect of turbulence and mussels reduced copepod and rotifer stocks, through physical processes and through filtration by zebra mussels, relative to the turbulence treatment. The reductions in the number of total zooplankton in the turbulent mixing mesocosms and the further reduction of rotifer and copepod in the turbulence and mussels treatment coincided with a period of increased reliance of larval fathead minnows on these prey. Estimates of consumption from bioenergetics modeling and measured prey standing stocks indicated caloric resources of suitable prey in turbulence treatments during the early weeks of the experiment were insufficient to prevent starvation. Early mortality in the turbulence and mussels treatment likely released surviving fish from intense intraspecific competition and resulted in higher individual growth rates. A combination of high abundance of zebra mussels in an environment with a well-mixed water column can have significant effects on larval fish survival and growth.

17α‐ethynylestradiol‐induced vitellogenin gene transcription quantified in livers of adult males, larvae, and gills of fathead minnows (Pimephales promelas)

We have applied a method for quantifying relative levels of messenger RNA (mRNA) transcription to assess chemically induced gene expression in fathead minnows (Pimephales promelas). Synthetic oligonucleotides designed for the fathead minnow vitellogenin gene transcription product were used in a reverse transcription polymerase chain reaction (RT-PCR) protocol. This sensitive and rapid strategy detected vitellogenin gene transcription in livers of male fathead minnows exposed to concentrations as low as 2 ng/L of the endocrine-disrupting compound 17alpha-ethynylestradiol for 24 h. Surprisingly, vitellogenin transcription products also were detected in gill tissue and in 48-h-old posthatch fathead minnow larvae. Relative levels of vitellogenin gene induction among individuals were quantified in a single-step reaction (PCR multiplex) with 18S rRNA universal primers and Competimers concurrently with fathead minnow vitellogenin oligonucleotides. This quantitative approach will markedly enhance detection of the first cellular event of estrogenic exposure to aquatic ecosystems in both field and laboratory systems. Use of the model provides sensitivity of detection at a concentration below those that cause mortality or visible signs of stress in fish or other aquatic organisms. The model may also provide an in vivo screening method for estrogenlike endocrine-disrupting compounds.

The Influence of Water Hardness, pH, and Suspended Solids on Nickel Toxicity to Larval Fathead Minnows (Pimephales promelas)

Nickel (Ni) is an ubiquitous, naturally occurring metalthat is associated with metal mining and other industrialactivities. Despite elevated Ni concentrations reportedfor many industrial receiving waters, Ni receives littleresearch attention addressing factors influencing itstoxicity to freshwater fish. This study examined theinfluence of water hardness, pH, and total suspended solids(TSS) in soft, reconstituted water on Ni toxicity to larvalfathead minnows (Pimephales promelas). Increasingwater hardness from 20 to 140 mg L-1 (as CaCO3) reduced acute Ni toxicity by 5-fold (96-h LC50s 0.45 and 2.27 mg Ni L-1, respectively). Low pH had a slight protective effect against Ni toxicity relative to neutral pH conditions. At pH 5.5, the 96-h LC50 was 0.69 mg Ni L-1, compared to 0.54 mg Ni L-1 at pH 7.0. However,Ni toxicity was significantly reduced at pH 8.5 where the 96-h LC50 was 2.21 mg Ni L-1. These results were explainedon the basis of Ni speciation. Total suspended solids also reduced Ni toxicity (expressed as 96-h LC50s) from 0.35 to 1.12 mg Ni L-1 over a TSS range of 10 to 100 mg L-1.This reduction of toxicity due to TSS is significant becausemine effluents often have a combination of elevated TSS andmetals. The ameliorative effect of TSS was not as significantas high hardness or pH probably because there is a TSS threshold, after which physical irritation to fish gills counteracts any protective effect conferred by TSS. This finding is relevant to choices made in design of mine effluenttreatment systems; i.e., there may be an optimum range ofTSS concentrations that protect aquatic biota againsteffects of metals that remain after treatment.

Toxicity of Uranium Mine-Receiving Waters to Caged Fathead Minnows, Pimephales promelas

Larval fathead minnows (Pimephales promelas) were placed at four exposure sites for 7 days in each of five lakes surrounding the Key Lake uranium mine in northern Saskatchewan, Canada. Fish placed in lakes receiving Mo-contaminated mill effluent demonstrated higher mortalities than those placed in lakes receiving Ni-contaminated mine-dewatering effluent, which was not significantly different from reference sites. No significant differences were detected in fish growth among the study lakes because of the high (90%) mortality in Fox and Unknown lakes. Principal components analysis characterized exposure sites by total and dissolved metal concentration. Stepwise multiple regression of fish mortality on principal components generated from total metal data revealed that principal component 1 could account for 84% of the variance associated with fish mortality. Careful examination of the metals that correlated strongly with principal component 1 and with fish mortality suggested that dietary Se toxicity probably resulted in the differential fathead minnow mortality observed among study lakes.

Evaluation of Fish Models of Soluble Epoxide Hydrolase Inhibition

Substituted ureas and carbamates are mechanistic inhibitors of the soluble epoxide hydrolase (sEH). We screened a set of chemicals containing these functionalities in larval fathead minnow (Pimphales promelas) and embryo/larval golden medaka (Oryzias latipes) models to evaluate the utility of these systems for investigating sEH inhibition in vivo. Both fathead minnow and medaka sEHs were functionally similar to the tested mammalian orthologs (murine and human) with respect to substrate hydrolysis and inhibitor susceptibility. Low lethality was observed in either larval or embryonic fish exposed to diuron [N-(3,4-dichlorophenyl), N'-dimethyl urea], desmethyl diuron [N-(3,4-dichlorophenyl), N'-methyl urea], or siduron [N-(1-methylcyclohexyl), N'-phenyl urea]. Dose-dependent inhibition of sEH was a sublethal effect of substituted urea exposure with the potency of siduron &lt; desmethyl diuron = diuron, differing from the observed in vitro sEH inhibition potency of siduron &gt; desmethyl diuron &gt; diuron. Further, siduron exposure synergized the toxicity of trans-stilbene oxide in fathead minnows. Medaka embryos exposed to diuron, desmethyl diuron, or siduron displayed dose-dependent delays in hatch, and elevated concentrations of diuron and desmethyl diuron produced developmental toxicity. The dose-dependent toxicity and in vivo sEH inhibition correlated, suggesting a potential, albeit undefined, relationship between these factors. Additionally, the observed inversion of in vitro to in vivo potency suggests that these fish models may provide tools for investigating the in vivo stability of in vitro inhibitors while screening for untoward effects.

Evaluation of fish models of soluble epoxide hydrolase inhibition.

Substituted ureas and carbamates are mechanistic inhibitors of the soluble epoxide hydrolase (sEH). We screened a set of chemicals containing these functionalities in larval fathead minnow (Pimphales promelas) and embryo/larval golden medaka (Oryzias latipes) models to evaluate the utility of these systems for investigating sEH inhibition in vivo. Both fathead minnow and medaka sEHs were functionally similar to the tested mammalian orthologs (murine and human) with respect to substrate hydrolysis and inhibitor susceptibility. Low lethality was observed in either larval or embryonic fish exposed to diuron [N-(3,4-dichlorophenyl), N'-dimethyl urea], desmethyl diuron [N-(3,4-dichlorophenyl), N'-methyl urea], or siduron [N-(1-methylcyclohexyl), N'-phenyl urea]. Dose-dependent inhibition of sEH was a sublethal effect of substituted urea exposure with the potency of siduron < desmethyl diuron = diuron, differing from the observed in vitro sEH inhibition potency of siduron > desmethyl diuron > diuron. Further, siduron exposure synergized the toxicity of trans-stilbene oxide in fathead minnows. Medaka embryos exposed to diuron, desmethyl diuron, or siduron displayed dose-dependent delays in hatch, and elevated concentrations of diuron and desmethyl diuron produced developmental toxicity. The dose-dependent toxicity and in vivo sEH inhibition correlated, suggesting a potential, albeit undefined, relationship between these factors. Additionally, the observed inversion of in vitro to in vivo potency suggests that these fish models may provide tools for investigating the in vivo stability of in vitro inhibitors while screening for untoward effects.

Acute and chronic toxicity of nitrate to fathead minnows (Pimephales promelas), ceriodaphnia dubia, and Daphnia magna

AbstractIncreasing concentrations of nitrate in surface water and groundwater are becoming a worldwide concern, yet little information has been published on toxicity of nitrate to common organisms used for toxicity testing. The acute and chronic toxicity of nitrate (NO3‐N) to Ceriodaphnia dubia, Daphnia magna, and Pimephales promelas was investigated in 48‐h to 17‐d laboratory exposures. The 48‐h median lethal concentration (LC50) of nitrate to C. dubia and D. magna neonates was 374 mg/L NO3‐N and 462 mg/L NO3‐N. The no‐observed‐effect concentration (NOEC) and the lowest‐observed‐effect concentration (LOEC) for neonate production in C. dubia were 21.3 and 42.6 mg/L NO3‐N, respectively. The NOEC and LOEC values for neonate production in D. magna were 358 and 717 mg/L NO3‐N, respectively. The 96‐h LC50 for larval fathead minnows (P. promelas) was 1, 341 mg/L NO3‐N. The NOEC and LOEC for 7‐d larval and 11‐d embryo‐larval growth tests were 358 and 717 mg/L NO3‐N, respectively. Additional exposure of breeding P. promelas and their fertilized eggs to nitrate did not increase susceptibility further. The LC50 values for all species tested were above ambient concentrations of nitrate reported for surface water. However, the LOEC for C. dubia was within the range of concentrations that could be found in streams draining areas under extensive agricultural cultivation.

Fathead minnow histology atlas: worldwide web outreach and utilization

The fathead minnow ( Pimephales promelas), the ‘white rat’ of aquatic toxicological studies, is used in USEPA test protocols for examining acute, short-term chronic, early lifestage, and lifecycle toxicity. Additionally, a substantial database cataloguing fathead minnow sensitivity to toxicants is available both in the printed literature and online (AQUIRE, ECOTOX, etc.). Regulatory programs that monitor effluent discharges routinely perform bioassay tests with larval fathead minnows. Test endpoints include survival, growth and reproduction. Recent attention has been directed toward development of sensitive sublethal indicators of contaminant-induced stress in aquatic species. Histopathological identification and quantification of health effects and contaminant-induced lesions are used as such indicators. Identification of tissue lesions requires a baseline appreciation of normal tissue conditions. While histological atlases exist for several commercially valuable species (i.e. striped bass, salmonids, catfish), such a resource has been unavailable for cyprinids, the dominant family of freshwater fishes (with more than 2000 species worldwide including approximately 300 in North America). For this reason we have generated an atlas of photomicrographs detailing the normal microanatomy of the fathead minnow. Currently, the atlas is available as a work in progress on the worldwide web (WWW; http://som1.ab.umd.edu/AquaticPath/fhm). Development of the atlas was accomplished through routine histological preparation of representative tissue samples. Photomicrographs of tissue samples were taken at various magnifications and digitized for use in the atlas. Digital images were compiled by organ system into separate sections. Sections are navigable by index and images are retrievable via ‘hotbuttons’ and hypertext. A WWW version of the atlas will be available for hands-on demonstration. Methods of development and outreach capabilities will be reviewed.

Growth of fathead minnows in oilsand‐processed wastewater in laboratory and field

AbstractTwo waste products of Syncrude Canada Ltd. (SCL) oilsands mine are mature fine tailings (MFT), a toxic aqueous suspension of particles, organic acids, bitumen, and metals, and tailings pond water (TPW), a saline solution containing organic and inorganic contaminants. The chemical profiles of MFT interstitial water and TPW are very similar. Syncrude Canada has proposed disposing of MFT in constructed lakes, which would be lined with MFT and capped with clean water. As the MFT consolidates, MFT‐associated water would be released into the overlying watercap. Prototype ponds support fathead minnows (Pimephales promelas), but the long‐term viability of these populations is unknown. This study attempts to determine if exposure to MFT and TPW, a related waste product, affected growth of fathead minnow larvae in the laboratory and field. Laboratory larval growth bioassays (7 and 56 d) on whole effluent from numerous prototype ponds yielded no significant differences in dry weight, but one 7‐d bioassay showed reduced survival in two SCL sites. A 56‐d growth bioassay showed significant increases in length of fish exposed to SCL wastewater at 7 d but not at 28 or 56 d. Larvae exposed as embryos and then introduced into field mesocosms did display significant differences in dry weight. In this instance, fish exposed to wastewater were significantly larger during the laboratory portion of the test (initial), but after 21 d in a field mesocosm (final), they were similar in size or smaller than fish growing in nonprocessed water.

Application of a fish DNA damage assay as a biological toxicity screening tool for metal plating wastewater

AbstractThe utility of a fish DNA damage assay as a rapid monitoring tool was investigated. Metal plating wastewater was chosen as a sample because it contains various genotoxic metal species. Fish DNA damage assay results were compared to data generated from the conventional whole effluent toxicity (WET) test procedure. The Microtox® assay (Azur Environmental, Carlsbad, CA, USA) using Vibrio fischeri was also employed. Eleven samples from two metal plating companies were collected for this evaluation. For the fish DNA damage assay, 7‐d‐old fathead minnow larvae, Pimephalespromelas, were utilized. They were exposed to a series of dilutions at 20°C for 2 h. Whole effluent toxicity tests conducted in this study included two acute toxicity tests with Daphnia magna and fathead minnows and two chronic toxicity tests with Ceriodaphnia dubia and fathead minnows. The fish DNA damage assay showed good correlations with both the acute and chronic WET test results, especially with those obtained with fathead minnows. The kappa values, an index of agreement, between the fish DNA damage assay and WET tests were shown to be acceptable (kappa ≥ 0.55). These findings imply that this novel fish DNA damage assay has use as an expedient toxicity screening procedure since it produces comparable results to those of the acute and chronic fathead minnow toxicity tests.

Heritable reproductive effects of benzo[a]pyrene on the fathead minnow (Pimephales promelas)

AbstractEnvironmental toxicologists rarely investigate multigeneration effects of aquatic contaminants. In this study we investigated the survivorship of fathead minnow larvae two generations removed from an exposure to the potent mutagen benzo[a]pyrene. The F2 broods with a grandparental exposure history showed a marked decrease in survival. In the highest‐exposure group, reproductive capacity and larval survivorship were significantly lower than the solvent control.

The effects of tetrachloroguaiacol on the growth, survival, and development of the fathead minnow, Pimephales promelas.

Fathead minnow (Pimephales promelas) larvae were exposed for 7 days to tetrachloroguaiacol (TeCG), within 24 h of hatching, at concentrations of 0, 25, 50, 100, 200, 400 microg/L. No significant difference in growth or larval survival was found among treatments. Embryos, within 24 h of fertilization, were also exposed to TeCG at concentrations of 0 and 100 microg/L for 10 days. No significant difference was found between the control and treatment groups for larval survival, body length, body width, or for yolk size of the eleutheroembryos. However, a significant difference was found in the hatching success of the eggs (p = 0.05). Since fathead minnows have been known to spawn in areas close to sites that discharge bleached kraft mill effluent (BKME) which contains TeCG, into receiving waters, naturally occurring populations will likely be affected by the toxicant.

Physiological Responses of Fathead Minnow Larvae to Rice Pesticides

Newly hatched fathead minnow ( Pimephales promelas) larvae were exposed for 4 days to two pesticides and ambient receiving waters to simulate conditions in the Sacramento River, California, during the striped bass spawning season which coincides with pesticide use in adjacent rice culture. Carbofuran and molinate were tested at two concentrations: a higher level approximating one-half the LC 50and a level much lower that is similar to that seen in the receiving waters of Colusa Basin Drain. Physiological measurements were made immediately after the exposures and again after a 10-day recovery period in noncontaminated waters. These included growth rate, swimming capacity, response to a mild electric shock, upper and lower lethal temperatures, and activity of acetylcholinesterase in whole-body homogenates. The higher concentrations of carbofuran and molinate caused reductions in swimming capacity, an increased sensitivity to the electric shock, and a reduction in upper lethal temperature. Acetylcholinesterase was reduced in those larvae exposed to the higher levels of carbofuran. In general, the lower levels of pesticide exposure caused no measureable effects nor did exposure to water from Colusa Basin Drain.

Exposure to acute low pH impairs chemoreception and feeding performance in larval fathead minnows (Pimephales promelas)

The impact of acute low pH exposure on feeding performance was investigated in larval fathead minnows. Sets of larvae were subjected to each of three pH concentrations (4.5, 5.5 and 7.7) under various conditions designed to isolate different sensory modalities. Temporal patterns in locomotor activity and number of larvae feeding were analyzed. Levels of locomotor activity were uncorrelated with feeding rates and were qualitatively different early vs. late in the larval phase. Under most conditions, locomotor activity decreased during the first few days posthatching, then increased over the remainder of the study. In contrast, feeding activity increased continually. Mechanoreception appeared to play a significant role in prey capture at pH 7.7, while photoreception contributed little. pH exposure had a significant negative impact on feeding success, though the nature of this effect varied with test conditions. Exposure to pH 4.5 appeared to strongly inhibit chemoreception; data also suggest close coupling of chemoreception and mechanoreception. These results point to the necessity for studies of acidification effects on larvae and suggest an approach by which aspects of sensory integration may be dissected.