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At least 1,279 records · Page 71Linked to original sources
USGS2008

Impairment of the reproductive potential of male fathead minnows by environmentally relevant exposures to 4-nonylphenolf

The synthetic organic compound 4-nonylphenol (NP) has been detected in many human-impacted surface waters in North America. In this study, we examined the ability of NP to alter reproductive competence in male fathead minnows after a 28 day flow-through exposure in a range of environmentally relevant concentrations bracketing the U.S. Environmental Protection Agency toxicity-based NP chronic exposure criterion of 6.1 μg NP/L. Exposure to NP at and above the EPA chronic exposure criterion resulted in an induction of plasma vitellogenin (VTG) within 14 days. However, 7 days after the cessation of exposure, VTG concentrations had dropped more than 50% and few males expressed VTG above the detection threshold. All of the morphological endpoints, including gonadosomatic index, hepatosomatic index, secondary sexual characters, and histopathology, were unaltered by all NP treatments. However, when NP-exposed male fish were allowed to compete with control males for access to nest sites and females, most treatments altered the reproductive competence of exposed males. At lower NP concentrations, exposed males out-competed control males, possibly by being primed through the estrogenic NP exposure in a fashion similar to priming by pheromones released from female fathead minnows. At higher NP exposure concentrations, this priming effect was negated by the adverse effects of the exposure and control males out-competed treated males. Results of this study indicate the complexity of endocrine disrupting effects and the need for multiple analysis levels to assess the effects of these compounds on aquatic organisms.

Aquatic Toxicology↗
USGS2008

Impacts of short-term acid and aluminum exposure on Atlantic salmon (Salmo salar) physiology: A direct comparison of parr and smolts

Episodic acidification resulting in increased acidity and inorganic aluminum (Al i ) is known to impact anadromous salmonids and has been identified as a possible cause of Atlantic salmon population decline. Sensitive life-stages such as smolts may be particularly vulnerable to impacts of short-term (days–week) acid/Al exposure, however the extent and mechanism(s) of this remain unknown. To determine if Atlantic salmon smolts are more sensitive than parr to short-term acid/Al, parr and smolts held in the same experimental tanks were exposed to control (pH 6.3–6.6, 11–37 μg l −1 Al i ) and acid/Al (pH 5.0–5.4, 43–68 μg l −1 Al i ) conditions in the lab, and impacts on ion regulation, stress response and gill Al accumulation were examined after 2 and 6 days. Parr and smolts were also held in cages for 2 and 6 days in a reference (Rock River, RR) and an acid/Al-impacted tributary (Ball Mountain Brook, BMB) of the West River in Southern Vermont. In the lab, losses in plasma Cl − levels occurred in both control parr and smolts as compared to fish sampled prior to the start of the study, however smolts exposed to acid/Al experienced additional losses in plasma Cl − levels (9–14 mM) after 2 and 6 days, and increases in plasma cortisol (4.3-fold) and glucose (2.9-fold) levels after 6 days, whereas these parameters were not significantly affected by acid/Al in parr. Gill Na + ,K + -ATPase (NKA) activity was not affected by acid/Al in either life-stage. Both parr and smolts held at BMB (but not RR) exhibited declines in plasma Cl − , and increases in plasma cortisol and glucose levels; these differences were significantly greater in smolts after 2 days but similar in parr and smolts after 6 days. Gill NKA activity was reduced 45–54% in both life-stages held at BMB for 6 days compared to reference fish at RR. In both studies, exposure to acid/Al resulted in gill Al accumulation in parr and smolts, with parr exhibiting two-fold greater gill Al than smolts after 6 days. Our results indicate that smolts are more sensitive than parr to short-term acid/Al. Increased sensitivity of smolts appears to be independent of a reduction in gill NKA activity and greater gill Al accumulation. Instead, increased sensitivity of smolts is likely a result of both the acquisition of seawater tolerance while still in freshwater and heightened stress responsiveness in preparation for seawater entry and residence.

Aquatic Toxicology↗
USGS2008

Cadmium biodynamics in the oligochaete Lumbriculus variegatus and its implications for trophic transfer

It has become increasingly apparent that diet can be a major source of trace metal bioaccumulation in aquatic organisms. In this study, we examined cadmium uptake, efflux, and subcellular compartmentalization dynamics in the freshwater oligochaete Lumbriculus variegatus. L. variegatus is an important component of freshwater food webs in Europe and North America and is potentially useful as a standard food source for laboratory-based trophic transfer studies. Cadmium accumulation and depuration were each followed for 10 days. Rate constants of uptake (ku) and efflux (ke) were estimated and subcellular Cd compartmentalization was followed over the course of uptake and efflux. The partitioning of Cd into operationally-defined subcellular compartments was relatively consistent throughout the 20-day experiment, with the majority of Cd accumulating in the cytosol. No major changes in Cd compartmentalization were observed over uptake or depuration, but there appeared to be some exchange between heat-stable and heat-labile cytosolic protein fractions. Cadmium accumulation from solution was strongly affected by ambient calcium concentrations, suggesting competition between Cd and Ca for uptake sites. Finally, we demonstrate the ability to manipulate the whole body calcium content of L. variegatus as a potential tool for examining calcium influences on dietary Cd dynamics. The potential for this species to be an important conduit of Cd to higher trophic levels is discussed, along with its potential as a standardized food source in metal trophic transfer studies. ?? 2007 Elsevier B.V. All rights reserved.

Aquatic Toxicology↗
USGS2009

The genomic transcriptional response of female fathead minnows ( Pimephales promelas ) to an acute exposure to the androgen, 17β-trenbolone

We investigated the genomic transcriptional response of female fathead minnows (Pimephales promelas) to an acute (4 days) exposure to 0.1 or 1.0 ??g/L of 17??-trenbolone (TB), the active metabolite of an anabolic androgenic steroid used as a growth promoter in cattle and a contaminant of concern in aquatic systems. Our objectives were to investigate the gene expression profile induced by TB, define biomarkers of exposure to TB, and increase our understanding of the mechanisms of adverse effects of TB on fish reproduction. In female gonad tissue, microarray analysis using a 22 K oligonucleotide microarray (EcoArray Inc., Gainesville, FL) showed 99 significantly upregulated genes and 741 significantly downregulated genes in response to 1 ??g TB/L. In particular, hydroxysteroid (17??) dehydrogenase 12a (hsd17b12a), zona pellucida glycoprotein 2.2 (zp2.2), and protein inhibitor of activated STAT, 2 (pias2) were all downregulated in gonad. Q-PCR measurements in a larger sample set were consistent with the microarray results in the direction and magnitude of these changes in gene expression. However, several novel potential biomarkers were verified by Q-PCR in the same samples, but could not be validated in independent samples. In liver, Q-PCR measurements showed a significant decrease in vitellogenin 1 (vtg1) mRNA expression. In brain, cytochrome P450, family 19, subfamily A, polypeptide 1b (cyp19a1b, previously known as aromatase B) transcript levels were significantly reduced following TB exposure. Our study provides a candidate gene involved in mediating the action of TB, hsd17b12a, and two potential biomarkers sensitive to acute TB exposure, hepatic vtg1 and brain cyp19a1b.

Aquatic Toxicology↗
USGS2009

Aroclor 1248 exposure leads to immunomodulation, decreased disease resistance and endocrine disruption in the brown bullhead, Ameiurus nebulosus

The brown bullhead Ameiurus nebulosus is a species of the family Ictaluridae commonly used as a sentinel of environmental contamination. While these fish have been utilized for this purpose in areas contaminated with polychlorinated biphenyls (PCBs), few controlled, laboratory-based studies have been designed to document the effects of PCB mixtures in this species. Here, brown bullhead were exposed to the PCB mixture, Aroclor 1248, via intraperitoneal injection and the effects on immune function, plasma hormones and disease resistance were evaluated. Exposure to this mixture led to a decrease in bactericidal activity and circulating antibodies to Edwardsiella ictaluri present from a previous exposure to this pathogen. A subsequent E. ictaluri disease challenge led to significantly higher mortality in A1248 treated fish compared to vehicle-control fish. The mitogenic response to the T-cell mitogen, phytohemaglutinin-P, was increased compared to vehicle-control fish. The steroid hormone, cortisol, and the thyroid hormone, T3, were also significantly lower in A1248 exposed fish. In summary, we have validated a number of functional immune assays for application in brown bullhead immunotoxicity studies. Additionally, we have demonstrated that the PCB mixture (A1248) modulates both immune function and endocrine physiology in brown bullhead. Such data may compliment the interpretation of data yielded from applied field studies conducted in PCB contaminated aquatic ecosystems.

Aquatic Toxicology↗
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↗
USGS2009

Changes in reproductive biomarkers in an endangered fish species (bonytail chub, Gila elegans) exposed to low levels of organic wastewater compounds in a controlled experiment

In arid regions of the southwestern United States, municipal wastewater treatment plants commonly discharge treated effluent directly into streams that would otherwise be dry most of the year. A better understanding is needed of how effluent-dependent waters (EDWs) differ from more natural aquatic ecosystems and the ecological effect of low levels of environmentally persistent organic wastewater compounds (OWCs) with distance from the pollutant source. In a controlled experiment, we found 26 compounds common to municipal effluent in treatment raceways all at concentrations <1.0 μg/L. Male bonytail chub (Gila elegans) in tanks containing municipal effluent had significantly lower levels of 11-ketotestosterone (p = 0.021) yet higher levels of 17β-estradiol (p = 0.002) and vitellogenin (p = 0.036) compared to control male fish. Female bonytail chub in treatment tanks had significantly lower concentrations of 17β-estradiol than control females (p = 0.001). The normally inverse relationship between primary male and female sex hormones, expected in un-impaired fish, was greatly decreased in treatment (r = 0.00) versus control (r = −0.66) female fish. We found a similar, but not as significant, trend between treatment (r = −0.45) and control (r = −0.82) male fish. Measures of fish condition showed no significant differences between male or female fish housed in effluent or clean water. Inter-sex condition did not occur and testicular and ovarian cells appeared normal for the respective developmental stage and we observed no morphological alteration in fish. The population-level impacts of these findings are uncertain. Studies examining the long-term, generational and behavioral effects to aquatic organisms chronically exposed to low levels of OWC mixtures are needed.

Aquatic Toxicology↗
USGS2010

Physiological, molecular, and cellular mechanisms of impaired seawater tolerance following exposure of Atlantic salmon, Salmo salar, smolts to acid and aluminum

We examined the physiological, molecular, and cellular mechanisms of impaired ion regulation in Atlantic salmon, Salmo salar, smolts following acute acid and aluminum (Al) exposure. Smolts were exposed to: control (pH 6.5, 3.4??gl-1 Al), acid and low Al (LAl: pH 5.4, 11??gl-1 Al), acid and moderate Al (MAl: pH 5.3, 42??gl-1 Al), and acid and high Al (HAl: pH 5.4, 56??gl-1 Al) for two and six days. At each time-point, smolts were sampled directly from freshwater treatment tanks and after a 24h seawater challenge. Exposure to acid/MAl and acid/HAl led to accumulation of gill Al, substantial alterations in gill morphology, reduced gill Na+/K+-ATPase (NKA) activity, and impaired ion regulation in both freshwater and seawater. Exposure to acid/MAl for six days also led to a decrease in gill mRNA expression of the apical Cl- channel (cystic fibrosis transmembrane conductance regulator I), increased apoptosis upon seawater exposure, an increase in the surface expression of mitochondria-rich cells (MRCs) within the filament epithelium of the gill, but reduced abundance of gill NKA-positive MRCs. By contrast, smolts exposed to acid and the lowest Al concentration exhibited minor gill Al accumulation, slight morphological modifications in the gill, and impaired seawater tolerance in the absence of a detectable effect on freshwater ion regulation. These impacts were accompanied by decreased cell proliferation, a slight increase in the surface expression of MRCs within the filament epithelium, but no impact on gill apoptosis or total MRC abundance was observed. However, MRCs in the gills of smolts exposed to acid/LAl exhibited morphological alterations including decreased size, staining intensity, and shape factor. We demonstrate that the seawater tolerance of Atlantic salmon smolts is extremely sensitive to acute exposure to acid and low levels of Al, and that the mechanisms underlying this depend on the time-course and severity of Al exposure. We propose that when smolts are exposed to acid and moderate to high Al concentrations, impaired seawater tolerance results from extensive gill Al accumulation, damage to the epithelium, reduced MRC and transport protein abundance, and a synergistic stimulation of apoptosis in the gill upon seawater exposure. When smolts are exposed to acid and low levels of Al, loss of seawater tolerance appears to be independent of these mechanisms and may result instead from a shift in the phenotype of MRCs present in the gill epithelium. ?? 2010 Elsevier B.V..

Aquatic Toxicology↗
USGS2010

Atrazine reduces reproduction in fathead minnow (Pimephales promelas)

Atrazine, the widely used herbicide, has shown to affect the hypothalamus–pituitary–gonad axis in certain vertebrate species, but few studies have examined reproductive effects of this chemical on fish. Our study was designed to evaluate a population endpoint (egg production) in conjunction with histological (e.g., gonad development) and biochemical (e.g., hormone production) phenotypes associated with atrazine exposure in fathead minnows. Adult virgin breeding groups of 1 male and 2 females were exposed to nominal concentrations of 0, 0.5, 5.0, and 50 μg/L of atrazine in a flow-through diluter for 14 or 30 days. Total egg production was lower (19–39%) in all atrazine-exposed groups as compared to the controls. The decreases in cumulative egg production of atrazine treated fish were significant by 17–20 days of exposure. Reductions in egg production in atrazine treatment groups were most attributable to reduced numbers of spawning events with increased atrazine exposure concentrations. Gonad abnormalities were observed in both male and female fish of atrazine-exposed fish. Our results also indicate that atrazine reduces egg production through alteration of final maturation of oocytes. The reproductive effects observed in this study warrant further investigation and evaluation of the potential risks posed by atrazine, particularly feral populations of fish from streams in agricultural areas with high use of this herbicide.

Aquatic Toxicology↗
USGS2011

Demasculinization of male fish by wastewater treatment plant effluent

Adult male fathead minnows ( Pimephales promelas ) were exposed to effluent from the City of Boulder, Colorado wastewater treatment plant (WWTP) under controlled conditions in the field to determine if the effluent induced reproductive disruption in fish. Gonadal intersex and other evidence of reproductive disruption were previously identified in white suckers ( Catostomus commersoni ) in Boulder Creek downstream from this WWTP effluent outfall. Fish were exposed within a mobile flow-through exposure laboratory in July 2005 and August 2006 to WWTP effluent (EFF), Boulder Creek water (REF), or mixtures of EFF and REF for up to 28 days. Primary (sperm abundance) and secondary (nuptial tubercles and dorsal fat pads) sex characteristics were demasculinized within 14 days of exposure to 50% and 100% EFF. Vitellogenin was maximally elevated in both 50% and 100% EFF treatments within 7 days and significantly elevated by 25% EFF within 14 days. The steroidal estrogens 17β-estradiol, estrone, estriol, and 17α-ethynylestradiol, as well as estrogenic alkylphenols and bisphenol A were identified within the EFF treatments and not in the REF treatment. These results support the hypothesis that the reproductive disruption observed in this watershed is due to endocrine-active chemicals in the WWTP effluent.

Colorado↗
USGS2011

Selective uptake and biological consequences of environmentally relevant antidepressant pharmaceutical exposures on male fathead minnows

Antidepressant pharmaceuticals have been reported in wastewater effluent at the nanogram to low microgram-per-liter range, and include bupropion (BUP), fluoxetine (FLX), sertraline (SER), and venlafaxine (VEN). To assess the effects of antidepressants on reproductive anatomy, physiology, and behavior, adult male fathead minnows ( Pimeplwles promelas ) were exposed for 21 days either to a single concentration of the antidepressants FLX, SER, VEN, or BUP, or to an antidepressant mixture. The data demonstrated that exposure to VEN (305 ng/L and 1104 ng/L) and SER (5.2 ng/L) resulted in mortality. Anatomical alterations were noted within the testes of fish exposed to SER and FLX, both modulators of the neurotransmitter serotonin. Additionally, FLX at 28 ng/L induced vitellogenin in male fish&mdash;a common endpoint for estrogenic endocrine disruption. Significant alterations in male secondary sex characteristics were noted with single exposures. Effects of single compound exposures neither carried over, nor became additive in the antidepressant mixtures, and reproductive behavior was not affected. Analysis of brain tissues from the exposed fish suggested increased uptake of FLX, SER and BUP and minimal uptake of VEN when compared to exposure water concentrations. Furthermore, the only metabolite detected consistently in the brain tissues was norfluoxetine. Similar trends of uptake by brain tissue were observed when fish were exposed to antidepressant mixtures. The present study demonstrates that anatomy and physiology, but not reproductive behavior, can be disrupted by exposure to environmental concentrations of some antidepressants. The observation that antidepressant uptake into fish tissues is selective may have consequences on assessing the mode-of-action and effects of these compounds in future studies.

Aquatic Toxicology↗
USGS2012

The effect of nonylphenol on gene expression in Atlantic salmon smolts

The parr–smolt transformation in Atlantic salmon (Salmo salar) is a complex developmental process that culminates in the ability to migrate to and live in seawater. Exposure to environmental contaminants like nonylphenol can disrupt smolt development and may be a contributing factor in salmon population declines. We used GRASP 16K cDNA microarrays to investigate the effects of nonylphenol on gene expression in Atlantic salmon smolts. Nonylphenol exposure reduced gill Na+/K+-ATPase activity and plasma cortisol and triiodothyronine levels. Transcriptional responses were examined in gill, liver, olfactory rosettes, hypothalamus, and pituitary. Expression of 124 features was significantly altered in the liver of fish exposed to nonylphenol; little to no transcriptional effects were observed in other tissues. mRNA abundance of genes involved in protein biosynthesis, folding, modification, transport and catabolism; nucleosome assembly, cell cycle, cell differentiation, microtubule-based movement, electron transport, and response to stress increased in nonylphenol-treated fish. This study expands our understanding of the effect of nonylphenol on smolting and provides potential targets for development of biomarkers.

Aquatic Toxicology↗
USGS2014

Comparative responses to endocrine disrupting compounds in early life stages of Atlantic salmon, Salmo salar

Atlantic salmon (Salmo salar) are endangered anadromous fish that may be exposed to feminizing endocrine disrupting compounds (EDCs) during early development, potentially altering physiological capacities, survival and fitness. To assess differential life stage sensitivity to common EDCs, we carried out short-term (four day) exposures using three doses each of 17&alpha;-ethinylestradiol (EE2), 17&beta;-estradiol (E2), and nonylphenol (NP) on four early life stages; embryos, yolk-sac larvae, feeding fry and one year old smolts. Differential response was compared using vitellogenin (Vtg, a precursor egg protein) gene transcription. Smolts were also examined for impacts on plasma Vtg, cortisol, thyroid hormones (T4/T3) and hepatosomatic index (HSI). Compound-related mortality was not observed in any life stage, but Vtg mRNA was elevated in a dose-dependent manner in yolk-sac larvae, fry and smolts but not in embyos. The estrogens EE2 and E2 were consistently stronger inducers of Vtg than NP. Embryos responded significantly to the highest concentration of EE2 only, while older life stages responded to the highest doses of all three compounds, as well as intermediate doses of EE2 and E2. Maximal transcription was greater for fry among the three earliest life stages, suggesting fry may be the most responsive life stage in early development. Smolt plasma Vtg was also significantly increased, and this response was observed at lower doses of each compound than was detected by gene transcription suggesting this is a more sensitive indicator at this life stage. HSI was increased at the highest doses of EE2 and E2 and plasma T3 decreased at the highest dose of EE2. Our results indicate that all life stages after hatching are potentially sensitive to endocrine disruption by estrogenic compounds and that physiological responses were altered over a short window of exposure, indicating the potential for these compounds to impact fish in the wild.

Aquatic Toxicology↗
USGS2014

Atrazine reduces reproduction in Japanese medaka (Oryzias latipes)

Atrazine is an effective broadleaf herbicide and the second most heavily used herbicide in the United States. Effects along the hypothalamus–pituitary–gonad axis in a number of vertebrate taxa have been demonstrated. Seasonally elevated concentrations of atrazine in surface waters may adversely affect fishes, but only a few studies have examined reproductive effects of this chemical. The present study was designed to evaluate a population endpoint (egg production) in conjunction with histological (reproductive stage, gonad pathology) and biochemical (aromatase activity, sex hormone production) phenotypes associated with atrazine exposure in Japanese medaka. Adult virgin breeding groups of one male and four females were exposed to nominal concentrations of 0, 0.5, 5.0, and 50 μg/L (0, 2.3, 23.2, 231 nM) of atrazine in a flow-through diluter for 14 or 38 days. Total egg production was lower (36–42%) in all atrazine-exposed groups as compared to the controls. The decreases in cumulative egg production of atrazine-treated fish were significant by exposure day 24. Reductions in total egg production in atrazine treatment groups were most attributable to a reduced number of eggs ovulated by females in atrazine-treated tanks. Additionally, males exposed to atrazine had a greater number of abnormal germ cells. There was no effect of atrazine on gonadosomatic index, aromatase protein, or whole body 17 β-estradiol or testosterone. Our results suggest that atrazine reduces egg production through alteration of final maturation of oocytes. The reduced egg production observed in this study was very similar to our previously reported results for fathead minnow. This study provides further information with which to evaluate atrazine's risk to fish populations.

Aquatic Toxicology↗
USGS2015

Sublethal red tide toxin exposure in free-ranging manatees (Trichechus manatus) affects the immune system through reduced lymphocyte proliferation responses, inflammation, and oxidative stress

The health of many Florida manatees (Trichechus manatus latirostris) is adversely affected by exposure to blooms of the toxic dinoflagellate, Karenia brevis. K. brevis blooms are common in manatee habitats of Florida's southwestern coast and produce a group of cyclic polyether toxins collectively referred to as red tide toxins, or brevetoxins. Although a large number of manatees exposed to significant levels of red tide toxins die, several manatees are rescued from sublethal exposure and are successfully treated and returned to the wild. Sublethal brevetoxin exposure may potentially impact the manatee immune system. Lymphocyte proliferative responses and a suite of immune function parameters in the plasma were used to evaluate effects of brevetoxin exposure on health of manatees rescued from natural exposure to red tide toxins in their habitat. Blood samples were collected from rescued manatees at Lowry Park Zoo in Tampa, FL and from healthy, unexposed manatees in Crystal River, FL. Peripheral blood leukocytes (PBL) isolated from whole blood were stimulated with T-cell mitogens, ConA and PHA. A suite of plasma parameters, including plasma protein electrophoresis profiles, lysozyme activity, superoxide dismutase (SOD) activity, and reactive oxygen/nitrogen (ROS/RNS) species, was also used to assess manatee health. Significant decreases (p<0.05) in lymphocyte proliferation were observed in ConA and PHA stimulated lymphocytes from rescued animals compared to non-exposed animals. Significant correlations were observed between oxidative stress markers (SOD, ROS/RNS) and plasma brevetoxin concentrations. Sublethal exposure to brevetoxins in the wild impacts some immune function components, and thus, overall health, in the Florida manatee.

Florida↗
USGS2015

Biokinetics of different-shaped copper oxide nanoparticles in the freshwater gastropod, Potamopyrgus antipodarum

Sediment is recognized as a major environmental sink for contaminants, including engineered nanoparticles (NPs). Consequently, sediment-living organisms are likely to be exposed to NPs. There is evidence that both accumulation and toxicity of metal NPs to sediment-dwellers increase with decreasing particle size, although NP size does not always predict effects. In contrast, not much is known about the influence of particle shape on bioaccumulation and toxicity. Here, we examined the influence of copper oxide (CuO) NP shape (rods, spheres, and platelets) on their bioaccumulation kinetics and toxicity to the sediment-dwelling gastropod, Potamopyrgus antipodarum . The influence of Cu added as CuCl 2 (i.e., aqueous Cu treatment) was also examined. Exposure to sediment mixed with aqueous Cu or with different-shaped CuO NPs at an average measured exposure concentration of 207 &mu;g Cu per g dry weight sediment for 14 days did not significantly affect snail mortality. However, growth decreased for snails exposed to sediment amended with CuO NP spheres and platelets. P. antipodarum accumulated Cu from all Cu forms/shapes in significant amounts compared to control snails. In addition, once accumulated, Cu was efficiently retained (i.e., elimination rate constants were generally not significantly different from zero). Consequently, snails are likely to concentrate Cu over time, from both aqueous and NP sources, resulting in a high potential for toxicity.

Aquatic Toxicology↗
USGS2015

Biodynamics of copper oxide nanoparticles and copper ions in an oligochaete: Part I: relative importance of water and sediment as exposure routes

Copper oxide (CuO) nanoparticles (NPs) are widely used, and likely released into the aquatic environment. Both aqueous (i.e., dissolved Cu) and particulate Cu can be taken up by organisms. However, how exposure routes influence the bioavailability and subsequent toxicity of Cu remains largely unknown. Here, we assess the importance of exposure routes (water and sediment) and Cu forms (aqueous and nanoparticulate) on Cu bioavailability and toxicity to the freshwater oligochaete, Lumbriculus variegatus , a head-down deposit-feeder. We characterize the bioaccumulation dynamics of Cu in L. variegatus across a range of exposure concentrations, covering both realistic and worst-case levels of Cu contamination in the environment. Both aqueous Cu (Cu-Aq; administered as Cu(NO 3 ) 2 ) and nanoparticulate Cu (CuO NPs), whether dispersed in artificial moderately hard freshwater or mixed into sediment, were weakly accumulated by L. variegatus . Once incorporated into tissues, Cu elimination was negligible, i.e., elimination rate constants were in general not different from zero for either exposure route or either Cu form. Toxicity was only observed after waterborne exposure to Cu-Aq at very high concentration (305 &micro;gL -1 ), where all worms died. There was no relationship between exposure route, Cu form or Cu exposure concentration on either worm survival or growth. Slow feeding rates and low Cu assimilation efficiency (approximately 30%) characterized the uptake of Cu from the sediment for both Cu forms. In nature, L. variegatus is potentially exposed to Cu via both water and sediment. However, sediment progressively becomes the predominant exposure route for Cu in L. variegatus as Cu partitioning to sediment increases.

Aquatic Toxicology↗
USGS2016

Biodynamics of copper oxide nanoparticles and copper ions in an oligochaete - Part II: Subcellular distribution following sediment exposure

The use and likely incidental release of metal nanoparticles (NPs) is steadily increasing. Despite the increasing amount of published literature on metal NP toxicity in the aquatic environment, very little is known about the biological fate of NPs after sediment exposures. Here, we compare the bioavailability and subcellular distribution of copper oxide (CuO) NPs and aqueous Cu (Cu-Aq) in the sediment-dwelling worm Lumbriculus variegatus. Ten days (d) sediment exposure resulted in marginal Cu bioaccumulation in L. variegatus for both forms of Cu. Bioaccumulation was detected because isotopically enriched 65 Cu was used as a tracer. Neither burrowing behavior or survival was affected by the exposure. Once incorporated into tissue, Cu loss was negligible over 10 d of elimination in clean sediment (Cu elimination rate constants were not different from zero). With the exception of day 10, differences in bioaccumulation and subcellular distribution between Cu forms were either not detectable or marginal. After 10 d of exposure to Cu-Aq, the accumulated Cu was primarily partitioned in the subcellular fraction containing metallothionein-like proteins (MTLP, ≈40%) and cellular debris (CD, ≈30%). Cu concentrations in these fractions were significantly higher than in controls. For worms exposed to CuO NPs for 10 d, most of the accumulated Cu was partitioned in the CD fraction (≈40%), which was the only subcellular fraction where the Cu concentration was significantly higher than for the control group. Our results indicate that L. variegatus handle the two Cu forms differently. However, longer-term exposures are suggested in order to clearly highlight differences in the subcellular distribution of these two Cu forms.

Aquatic Toxicology↗