Douglas Holdway | University of Ontario Institute of Technology (original) (raw)

Papers by Douglas Holdway

Environmental Toxicology and Chemistry, Mar 1, 1986

Adult American flagfish (Jordunellu floridae) were exposed for 2 h to 1.6, 1.9, 3.1 or 5.1 mg L-'... more Adult American flagfish (Jordunellu floridae) were exposed for 2 h to 1.6, 1.9, 3.1 or 5.1 mg L-' of the chlorinated hydrocarbon insecticide methoxychlor. Control and ethanol-carrier control treatments were also maintained. Fish were sampled at 2, 6, 24, 48 and 336 h after exposure, and the concentrations of tryptophan, serotonin and 5-hydroxyindole acetic acid in brain tissue were determined. Flagfish exposed to the three highest concentrations of methoxychlor had significantly lower concentrations of serotonin, relative to controls, 2, 6 and 24 h after exposure. Serotonin concentrations had returned to control levels by 48 h. The period of serotonin depression corresponded with observed convulsive activity in the exposed fish. Female flagfish had significantly higher brain levels of serotonin than did males. Although tryptophan and 5-hydroxyindole acetic acid levels were unaffected by methoxychlor exposure, the levels of both were significantly depressed by the concentration of ethanol carrier (270 mg L-I) used. Serotonin levels were unaffected by ethanol. The brain weight of flagfish was found to be related to body weight by the equation brain weight (mg) = 2.53 + 5.72 body weight (g) (n = 139; r 2 = 0.74; p < 0.001).

Environmental Toxicology and Chemistry, Apr 1, 2020

Estrogen toxicity has been an area of priority in aquatic toxicology over the last 20 yr. Current... more Estrogen toxicity has been an area of priority in aquatic toxicology over the last 20 yr. Currently, estrogen toxicity is primarily linked to classical estrogen signaling, the interaction of estrogen receptors alpha and beta (ERα and ERβ). Recent evidence has indicated that a rapid, nongenomic, nonclassical estrogen signaling pathway exists via the G protein–coupled estrogen receptor (GPER), which is expressed in many biological systems, with roles in the cardiovascular system. The objective of the present study was to investigate the effect of 17α‐ethinylestradiol (EE2) on the heart rate of embryonic Japanese medaka (Oryzias latipes). A significant decrease (bradycardia) in embryonic heart rate was observed at all treatment concentrations (0.1, 1, 10, 100, and 1000 ng/L EE2) at 144, 168, and 192 h postfertilization (hpf; p ≤ 0.05), whereas 120 and 216 hpf embryos experienced a significant decrease from the control at 10, 100, and 1000 ng/L EE2 and 0.1, 100, and 1000 ng/L EE2, respectively (p ≤ 0.05). In addition, using select estrogen receptor modulators, it was demonstrated that estrogen‐induced bradycardia appears to be linked to GPER and not ERα and ERβ. The present study highlights GPER as a novel and alternative mode of action for EE2 toxicity at environmentally relevant concentrations. Environ Toxicol Chem 2020;39:904–912. © 2020 SETAC

Vanadium concentrations of 2.4 to 5.6 mg/L were lethal in 7 days to rainbow trout of wet weight 1... more Vanadium concentrations of 2.4 to 5.6 mg/L were lethal in 7 days to rainbow trout of wet weight 1.2-6.2 g. The LC50 varied slightly over the 12 combinations of water quality, from hardness 30 to 350 units and pH S.S to B.B. The 7-day LCSO may be estimated by the following equation, which explained 91% of the variation: LC50 = 14.6976-3.77B3P + 0.110BH-0.02137 PH + 0.2662p 2-0.000073H 2 + 0.00141p 2 H. where H = hardness as mg/L of CaC0 3 , and P = pH. v was about 0.007, close to such ratios for other pollutants. There was no evidence that vanadium had any long-term cumulative toxicity. Overall among the metals, vanadium was of moderate noncumulative toxicity. With respect to oil sands operations, there should be an assessment whether aerial fallout of vanadium could create undesirable levels in slow-turnover lakes. BACKGROUND AND PERSPECTIVE This study was authorized at the early stages of the Alberta Oil Sands Environmental Research Program. The goal of the project was to establish the thresholds for acute and chronic toxicity of vanadium for fish. Such knowledge would be necessary for an assessment of whether a vanadium problem in the aquatic environment could be caused by oil sands development activities. Both acute and chronic effects of vanadium were to be studied. The acute toxicity tests were to serve two purposes: (1) to obtain firm numbers on vanadium lethality to allow assessment of danger in comparison with other pollutants; and (2) to obtain a quick measure of toxicity in all types of water (for example, in soft acid waters) likely to be encountered to point out any peculiarities of vanadium effects. The chronic was designed to detect any long-term or sub-lethal effects which might affect fisheries production. The one-generation experiment with fish should show any effect, whether it results from accumulation, chronic morbidity, effects on reproduction capacity, growth, or other modes of action. The tests were to be run using ionic forms of vanadium. However, since vanadium may be released into the aquatic environment in a variety of forms, it was-recogni zed that there may be some limitation in directly applying the results to the AOSERP study area. Therefore, the researcher was directed to take into consideration the actual form of vanadium used in his tests. vi ASSESSMENT This project has been completed and the levels of vanadium causing acute and chronic effects in fish have been established. The report has been reviewed by scientists in Alberta Environment, Fisheries and Environment Canada, and the Alberta Agriculture Toxicology Laboratory; the censensus is that it is a well executed study. However, the conclusions of the report do not necessarily reflect the views of Alberta Environment or Fisheries and Environment Canada, and the mention of trades names for commerical products does not constitute an endorsement or recommendation for use. The Alberta Oil Sands ironmental Research Program is pleased with the efforts put forth by the researchers in this project and accepts their report, "Acute and Chronic Toxicity of Vanadium to Fish ll , as an important and valid document. The researchers are to be congratulated for their contribution.

Canadian Journal of Fisheries and Aquatic Sciences, 1987

Methoxychlor is currently pulsed into several western Canadian rivers at 0.30 mg∙L−1 to control t... more Methoxychlor is currently pulsed into several western Canadian rivers at 0.30 mg∙L−1 to control the emergence of blackflies (Diptera: Simuliidae). A 2-h exposure of white sucker (Catostomus commersoni)) eggs to 4.83 mg methoxychlor∙L−1 at 1, 3, or 6 d postfertilization increased the incidence of deformities in both 1-d-old and pooled 3- and 6-d-old eggs (2.9 and 3.1%, respectively) compared with control eggs(1.1%). Larvae from exposed eggs showed a 2-d delay in the onset of exogenous feeding. Exposure as eggs increased methoxychlor tolerance. Respective 168-h PE LC50s (the 2-h pulse-exposure concentration causing 50% mortality over 168 h) for 2-d-old larvae from control eggs and eggs exposed for 2 h to methoxychlor at 1, 3, or 6 d postfertilization were 0.36, 1.04, 2.05, and 2.67 mg∙L−1 Methoxychlor toxicity in control larvae was modified by age; 10-d-old larvae were less tolerant than 2-, 18-, and 26-d-old larve, with respective PE LC50s of 0.04, 0.36, 0.34, and 0.20 mg∙L−1. After the onset of feeding, food availability modified toxicity. The96-h PE LC50sfor 18-d-oldfedand unfed larvae and 26-d-old fed and unfed larvae were 0.34, 0.032, 0.20, and 0.038 mg∙L−1, respectively. Swimbladder development was arrested in 2-d-old larvae exposed for 2 h to 0.10 mg methoxychlor∙L−1 at 9 d of age. White sucker survival may be at risk in methoxychlor-treated rivers.

Fish Physiology and Biochemistry, Jul 1, 1988

Levels of serotonin, 5-hydroxyindoleacetic acid, tryptophan, noradrenalin and dopamine were deter... more Levels of serotonin, 5-hydroxyindoleacetic acid, tryptophan, noradrenalin and dopamine were determined in whole brains of male (dominant, subordinate, solitary and resting) and female (laying and resting) flagfish (Jordanella floridae) and related to reproductive activity. Levels of serotonin were consistently elevated in sexually active male flagfish, relative to resting males. Dominant males exhibited lower noradrenalin levels than all other groups of fish. Solitary males exhibited higher levels of noradrenalin than dominant males, and were not significantly different from resting males. The lowest levels of tryptophan were apparent in brains of sexually inactive males and females. Neither sex nor reproductive status had a significant impact on 5-hydroxyindoleacetic acid levels. The hatchability of eggs fertilized by solitary males was reduced by over 40% when compared to dominant males.

Several studies have demonstrated the potential for induction of the cytochrome P450 biotransform... more Several studies have demonstrated the potential for induction of the cytochrome P450 biotransformation enzymes to interfere with reproduction. The polychlorinated biphenyl (PCB) isomer 3,3{prime},4,4{prime},5 pentachlorobiphenyl, is a major component of the EROD inducing fraction of commercial PCB mixtures which have been shown to have adverse effects on reproductive function. Australian crimson-spotted rainbow fish (Melanotaenia fluviatilis) were exposed for 8 or 21 days to either 3,3{prime},4,4{prime},5-PCB (approx 0.2 ttg/fish/day) contaminated food or carrier control food. EROD and ECOD activities were measured on livers collected at the end of exposure. Reproductive performance was monitored throughout the exposure as rainbow fish produce eggs daily. Female EROD activity (nmol/min/g of liver) was elevated by PCB exposure 2.6 and 2.2 fold at days 8 and 21 respectively. Female ECOD activity was elevated 1.8 fold on day 21 only. There was a trend towards elevated male EROD at both sampling intervals. Male ECOD was not significantly altered. There was no effect of PCB on egg and larvae numbers or hatchability. In summary, these results show that induction of EROD activity was not associated with impairment of reproductive function, but represented a potentially useful biomarker of PCB exposure in female crimson spotted rainbow fish.

Water Quality Research Journal of Canada, May 1, 2007

An examination of acetylcholinesterase (AChE), citrate synthase (CS) and lactate dehydrogenase (L... more An examination of acetylcholinesterase (AChE), citrate synthase (CS) and lactate dehydrogenase (LDH) activities in the brains of a range of fish species, occupying different trophic levels, is useful to investigate the full extent of the effects of sublethal or pulse exposures to pesticides. This investigation explores the optimization of microplate procedures for AChE, CS and LDH measurements in the brain tissue of species commonly used in laboratory investigations and those common to Canadian watersheds. A microplate assay was optimized for the measurement of AChE in the brain homogenates of seven fish species. The critical aspects of this assay requiring optimization were pH, substrate concentration and tissue dilution. Incubation with specific cholinesterase inhibitors indicated that enzymatic activity in the brain homogenates of each species was attributed to AChE only. Microplate assays were also optimized for the measurement of the metabolic enzymes, CS and LDH, in the brain homogenates of six fish species. For these assays, low interspecies variability was exhibited between optimized factors including pH, substrate, chromogen and cofactor concentrations. For each assay optimized, enzyme activities in the brain homogenates were stable for 2 to 3 hours post-thaw. Results from the present study will aid future ecotoxicological investigations of the potential impacts of AChE inhibition on neuronal glucose metabolism.

Aquatic Toxicology, May 1, 2021

This study leveraged the Japanese medaka fish embryo model for the assessment of effects of selec... more This study leveraged the Japanese medaka fish embryo model for the assessment of effects of select contaminants on early development in fish. Fish embryos were exposed to various pharmaceutical contaminants including synthetic hormones and non-steroidal anti-inflammatory drugs and their effects on development were observed. Initial screening determined that swim bladder inflation failure was the most common endpoint detected. Swim bladder inflation failure was first explored in a study demonstrating that medaka require access to the air-water interphase to inflate their swim bladders in a time-dependent manner, and swim bladder inflation failure was correlated with mortality. Fish embryos were exposed 24-hours post fertilization until hatch to concentration ranges of various pharmaceutical contaminants including: 17β-estradiol, 17α-ethinylestradiol, and levonorgestrel (1 to 1000 µg/L), or diclofenac (0.32 to 100 mg/L). The main effect observed across all four compounds was a significant increase in failure of swim bladder inflation with increasing exposure concentration (24 to 72-hours post-hatch). Following single compound experiments combinatorial exposures using no-observed-effect concentrations were conducted. The main effect observed was a significant decrease in inflation success 24-hours post-hatch following a binary mixture of levonorgestrel and 17α-ethinylestradiol, as well as a significant decrease in swim bladder inflation success at all times following exposure to a quaternary mixture of all four compounds. This study demonstrated that embryonic exposure to pharmaceutical compounds, both alone and in combination, resulted in failure of swim bladder inflation in larval Japanese medaka.

Environmental toxicology and water quality, Nov 1, 1995

The effects of very short pulse-exposures with the synthetic pyrethroid esfenvalerate on survival... more The effects of very short pulse-exposures with the synthetic pyrethroid esfenvalerate on survival and growth of larval crimson-spotted rainbow fish (Melanotaenia fluviatilis) were investigated in two series of experiments. Larval rainbow fish [2, 7, or 14 days (d) old] were pulse-exposed to esfenvalerate (30–700 ng L−1) for 1 h and then transferred to growth chambers where survival and growth were monitored for periods of 7–28 d, depending on the experimental protocol. Mortality was found to be a more sensitive indicator of pesticide effects than growth. Effects on growth were only observed in treatments where there was significant pesticide-related mortality. In these treatments, rainbow fish larvae were larger than control larvae. However, as increase in growth was always associated with mortality, it was not possible to determine if this was a direct effect of the pesticide or an artefact of density-dependent interactions within test populations. There was some evidence to suggest that pulse-exposure with esfenvalerate at an early age may cause subtle longterm detrimental effects to growth of larval rainbow fish. Dry weight and condition (length/weight) were more sensitive indicators of treatment effect than total length. Esfenvalerate was extremely toxic to larval fish, with 1 h pulse-exposures as low as 60 ng L−1 causing significant mortality. Newly hatched larvae were more sensitive to esfenvalerate than animals that were 14 d old. The effects of esfenvalerate on 7-d-old larvae could not be determined because of high control mortality. Larvae of this age undergo transition from endogenous to exogenous feeding and may be more sensitive to handling stress. The lowest 1 h pulse-exposure esfenvalerate no observed effect concentration and lowest observed effect concentration were <60 and 60 ng L−1 respectively, based on 2-d-old larval mortality. © by John Wiley & Sons, Inc.

Journal of Experimental Marine Biology and Ecology, May 1, 2006

... appears to be common in temperate asteroid species, as temperate zones are often subject to t... more ... appears to be common in temperate asteroid species, as temperate zones are often subject to the annual variation of physical parameters and biological conditions (Ventura et al ... This is similar to the approximate half-month lag reported in male Asterias rubens populations by.

Protection of tropical rivers from metal pollution requires that mining wastewaters be biological... more Protection of tropical rivers from metal pollution requires that mining wastewaters be biologically tested for aquatic toxicity before release from the site into natural ecosystems occurs, and that a 'safe' dilution which incorporates a minimum 10-fold safety factor applied to the lowest NOEC threshold value be utilized. Application of these test methods to wastewaters from an operating uranium mine has shown that pre-release toxicity testing provides accurate information on the toxicity of metal-containing wastewaters with a high degree of confidence. Field validation of the laboratory results was obtained when wastewaters which were field diluted through a release into a billabong gave similar results to laboratory-diluted wastewaters. No one species is always the most sensitive to exposure to complex wastewaters. Changes with time in wastewater chemistry, toxicity, and in the physiological capacity of specific organisms to survive in a contaminated environment (tolerance), can result in different species having varying sensitivities over time to exposure to complex wastewaters collected from the same location. As a result of the remote likelihood of finding the 'most sensitive species', it is necessary to test the toxicity of complex wastewaters to a batter), of organisms, representing different trophic levels of the ecosystem, under physical conditions representative of the specific environment needing protection. Use of a natural billabong as a 'biological filter' for releasing mine wastewaters did not result in toxicity mitigation and prevented controlled dilution from occurring during periods of high creek flow.

International Journal of Environmental Analytical Chemistry, Feb 1, 1988

Purge and Trap Gas Chromatographic Method for Dimethyl Sulfide in Freshwater. DA Holdway, JO Nria... more Purge and Trap Gas Chromatographic Method for Dimethyl Sulfide in Freshwater. DA Holdway, JO Nriagu International Journal of Environmental Analytical Chemistry IJEAA 3 32:3-43-4, 1988. A simple purge and trap method ...

Spill Science & Technology Bulletin, Oct 1, 2000

Marine Pollution Bulletin, Sep 1, 2005

The use of a non-lethal tool for evaluating toxicological hazard of organochlorine contaminants i... more The use of a non-lethal tool for evaluating toxicological hazard of organochlorine contaminants in Mediterranean cetaceans: new data 10 years after the first paper published in MPB.

Marine Pollution Bulletin, Jul 1, 1997

Environmental Toxicology and Chemistry, 1994

ABSTRACT European carp (Cyprinus carpio) exposed to highly treated pulp mill effluent in Lake Col... more ABSTRACT European carp (Cyprinus carpio) exposed to highly treated pulp mill effluent in Lake Coleman, a shallow-water lake in southern Victoria, Australia, had significantly elevated hepatic microsomal EROD levels relative to reference fish from a nearby unexposed water body (Dowds and Heart morasses). Mean hepatic microsomal EROD activity appeared to be correlated with site adsorbable organic halogen (AOX) levels, with a simple linear regression yielding the equation Y = 0.059X+ 1.415 (r2 = 0.93, n = 5), where Y is mean EROD activity in nanomoles per minute per milligram and X is mean AOX concentration in micrograms per liter. Mean liver EROD activity was poorly related with fish muscle-tissue extractable organic halogen (EOX) and sediment EOX concentrations. Hepatic microsomal EROD activity also appeared to be correlated with the low levels of PCDD/PCDFs measured in carp muscle (1.0-4.0 ppt TCDD international toxic equivalents (TEs) in effluent-exposed fish muscle compared to 0.48-0.64 ppt TEs in reference fish muscle). Simple linear regression of mean EROD activity in carp liver with the mean fish muscle dioxin content yielded the equation Y= 6.514X+ 5.754 (n = 4, r2 = 0.88), where Y is mean EROD activity in nanomoles per minute per milligram and X is mean dioxin concentration in ppt of TCDD TEs. Hepatic microsomal ECOD activity, however, was not significantly different at any exposure site from the reference sites. Overall, Lake Coleman contained between 4.5 and 9.3 times the water AOX levels, 0.8 and 13.7 times the sediment EOX levels, 1.5 and 2.2 times the carp muscle-fat EOX levels, 5.0 and 5.3 times the carp whole-muscle TCDD toxic equivalents, and 6.5 times the carp fat TCDD toxic equivalents, compared to the Dowds and Heart morass reference samples. Within Lake Coleman, mean liver microsomal EROD activity levels were 2.3 to 6.3 times higher than the Dowds and Heart reference sites, respectively. Tissue concentrations of PCDD/PCDF and water AOX levels reduced with increasing distance from the effluent point source. Carp liver microsomal EROD represented a good biomarker of exposure to low levels of organochlorine contaminants from well-treated pulp mill effluent.

Biochemical markers of exposure (mixed function oxygenase: MFO as determined by ethoxyresorufin O... more Biochemical markers of exposure (mixed function oxygenase: MFO as determined by ethoxyresorufin O-deethylase (EROD) activity) and of effect(sorbitol dehydrogenase:SDH) were investigated for use during and after exposure of Atlantic salmon (salmo salar) to low levels of Bass Strait crude oil water-accommodated fraction (WAF) and dispersed crude oil. EROD activity was significantly induced after only two days of exposure to dispersed oil,while four days of exposure were necessary to significantly induce EROD in the WAF-exposed salmon. Following the termination of exposure,EROD induction remained elevated for eight days in both the WAF-exposed and the dispersed oil-exposed fish. Dispersing the oil using Corexit 9527 produced similar EROD activity levels in salmon relative to WAF only. Serum SDH activity confirmed that no hepatocellular injury was caused by exposure of salmon to these levels of WAF or to dispersed Bass Strait crude oil. It is concluded that MFO induction,as measured by changes in EROD activity,can be used for confirmation of low-level exposure of commercial salmon stocks to petroleum contaminated waters for up to eight days after the event

The importance of appropriate oil spill remedial action was emphasized during the recent Iron Bar... more The importance of appropriate oil spill remedial action was emphasized during the recent Iron Barron oil spill off of the Tamar river in North Tasmania. One important potential oil spill response is dispersion, but little information exists on the toxicity of dispersants and dispersed oil to Australian marine species. This research was undertaken to assess the acute toxicity of Corexit 9527 (a widely used dispersant), water accommodated fractions of Bass Strait crude oil and dispersed Bass Strait crude oil, to the saltwater amphipod, Allorchestes compressa under semi-static conditions. Acute 96 h LC50`s were determined for each toxicant as well as for the reference toxicants sodium dodecyl sulfate (SDS) and zinc sulfate. Sublethal bioassays were undertaken for the same 3 toxicants utilizing the marines and snail Polinices conicus as the test species. No-observed-effect-concentrations (NOEC) and lowest-observed-effect-concentrations (LOEC) were determined using ANOVA while EC50`s and EC0`s were calculated using regression analysis. Mean acute 96 h LC50 (S.E.) values for A. compressa exposed to SDS and zinc sulfate were 3.6 mg/l (0.28) and 41.6 mg/l (9.01) respectively. EC50 (S.E.) concentrations for P. conicus exposed to SDS and zinc sulfate for 30 minutes were 44.7 mg/l and 246 mg/l respectively using burying behavior asmore » an endpoint. These sublethal EC50`s were reduced to 20.7 mg/l for SDS and 23.5 mg/l for zinc sulfate following 24 hours of exposure.« less

In Southern Australia, Atlantic salmon (Salmo salar) farming is undertaken in marine areas where ... more In Southern Australia, Atlantic salmon (Salmo salar) farming is undertaken in marine areas where extensive oil exploration, exploitation and transport are taking place. Pen-reared juvenile fish are at high risk of oil exposure through frequent small spills or major accidents. When exposed, commercial fisheries have to face million-dollar loses due to potential tainting of their stocks. In this study, juvenile Atlantic salmon were exposed to Bass Strait light crude oil in a fashion simulating an accidental oil spill at sea i.e. exposure to crude oil followed by a deputation period. Temporal trends in enzymatic bioindicators of exposure were investigated through exposure and deputation periods, as well as several biochemical and chemical measurements. The main objective of the study was to relate tainting with easily measured biological indicators of exposure to crude oil. Good correlations between bioindicators of exposure and tainting could assist fish farming industry to decide on the fate of fish stocks affected by oil taint.