Uptake of Nickel and Zinc by the Zebra Mussel Dreissena polymorpha

Short-term experiments with nickel and zinc radioisotopes showed that the zebra mussel Dreissena polymorpha takes up both “dissolved” (<0.45 μm) and particulate fractions of these metals in water. Uptake of particulate nickel was significant (despite a relatively low affinity of nickel for particulate matter), though less important than uptake of dissolved nickel. The relative importance of dissolved and particulate zinc varied from an almost exclusive uptake of dissolved zinc to uptake of particulate zinc only. This variability may reflect a dependence on the composition of the suspended particulate material, in line with the observation that zinc uptake and bioaccumulation were higher in high-turbidity water than in low-turbidity water. Metal excretion differed between the two metals; more than half of the accumulated zinc was excreted in twenty four hours, while no nickel excretion was evident. The mussels removed a larger proportion of total watercolumn zinc than of total watercolumn nickel. Of the metal removed from the watercolumn, a majority of the zinc was biodeposited (as feces/pseudofeces) while most of the nickel was bioaccumulated. These results indicate that the introduction of the zebra mussel will result in element-specific decreases of watercolumn metal levels, increases in metal bioaccumulation and increases in metal biodeposition. Results also indicate that D. polymorpha tissue metal levels obtained in biomonitoring programs will generally reflect both dissolved and particulate metal levels. Received: 27 February 1996/Revised: 24 June 1996     

Organophosphates in the Zebra Mussel Dreissena polymorpha: Subacute Exposure, Body Burdens, and Organ Concentrations

Subacute exposures (10 d) of the freshwater mollusc Dreissena polymorpha to disulfoton (10 mg/L), thiometon (6 mg/L), and its activated oxygen analogue demeton-S-methyl (6 mg/L) corroborate earlier findings of organophosphate resistance and accumulation in the organism. Mortality occurred not before the ninth day of exposure. Mortality was induced at high ambient water concentrations and must be due to unknown specific organophosphate effects. Body burdens reached saturation levels within one week being around 40 mg/kg wet weight for thiometon and 60 mg/kg for disulfoton. Mussels dying during the tests showed lower tissue concentrations. Elimination of accumulated organophosphates was so low in the mussel, that an efficient metabolism of these compounds in the mussel was unlikely. Different organs of Dreissena previously acutely exposed (96 h) to the organophosphate thiometon (6, 12, 25, 50 mg/L) were analyzed for their thiometon content. Thiometon could be found in all organs, but were highest in the anterior part of the viscera (230 mg/kg), where it was accumulated either in the digestive gland and/or in the gonadal tissue. Received: 13 April 1996/Revised: 21 November 1996     

Bioassays Using the Midge Chironomus riparius and the Zebra Mussel Dreissena polymorpha for Evaluation of River Water Quality

To evaluate if the water quality of the river Meuse affects macrofauna species, the impact of water from this river on two representative species was tested under controlled conditions. Short-term bioassays with reference populations of the midge Chironomus riparius and the zebra mussel Dreissena polymorpha were performed simultaneously, using growth and filtration rate as sublethal parameters, respectively. Filtration rates of mussels seemed to be slightly inhibited by Meuse water in 1994 and 1995, although this was only significant in the first year. Apparently, although this species is inhabiting the river Meuse, the water quality still causes sublethal effects. In contrast to the mussel, midges were less sensitive to Meuse water in laboratory experiments; growth inhibition was never observed, while in some experiments growth was even enhanced. In the period of testing, it was not possible to relate effects on macrofauna species in laboratory tests to individual substances in polluted river systems. Because the response of the test species was marginal, it is recommended to include more sensitive species as tested in the present study, especially in view of a general improvement of the water quality in the river Meuse. Received: 25 March 1997/Accepted: 6 November 1997     

Zebra mussels (Dreissena polymorpha) as indicators of freshwater contamination with lindane

Zebra mussels are common freshwater mollusks in many European lakes and rivers. Their abundance, wide distribution, and filtering activity make them good candidates to evaluate the contamination of freshwaters with environmental contaminants. The purpose of this work was to determine the kinetics of lindane in zebra mussels and compare laboratory results with in situ measurements. Exposure was conducted in small tanks, under controlled experimental conditions. Our results indicated that mussels accumulated lindane with a bioconcentration factor around 10. They generally reached equilibrium within 4 days. Elimination was rapid but biphasic and the terminal elimination half-life was long (> 168 h). Age of the mussels and temperature also affected the kinetics of lindane in mussels. In the Lake of Geneva, zebra mussels were sampled and showed that mussels accumulated it to significant values (up to 900 ng/g fresh weight) depending on the site and period of sampling. The in situ results, together with the laboratory exposures, showed that freshwater mussels could be used to monitor point sources of pollutants such as lindane over short periods of time (< 1 week).     

Toxicity of organophosphorus insecticides in the zebra mussel, Dreissena polymorpha P.

The 96-h toxicity of four organophosphates (thiometon, disulfoton, malathion, and demeton-S-methyl, the oxygen analogue of thiometon) in the freshwater bivalve mollusc Dreissena polymorpha was tested using different nominal concentrations ranging between 6 and 50 mg/L. No mortalities were observed in mussels exposed to malathion and demeton-S-methyl (26 mg/L and 6 mg/L, respectively), and at the lowest concentrations of thiometon and disulfoton (6 and 10 mg/L, respectively). At higher thiometon and disulfoton concentrations, mortalities occurred. At the highest concentrations of 50 mg thiometon/L and 30 mg disulfoton/L, mussel mortalities of 88 and 93%, respectively, were determined. Organophosphate concentrations of up to a factor 10 times higher than in the ambient water were found in exposed mussels, irrespective of whether they were alive or dead. The search for organophosphate metabolites via GC/MS analysis of mussel tissue extracts was negative, suggesting lacking or low oxidative activation of the insecticides used. The mollusc is highly resistant to toxic effects of organophosphate insecticides and their biological active oxygen analogues.     

水溶性塑料薄膜对斑马鱼的急性毒性

目的研究水溶性塑料薄膜对斑马鱼的毒性,为其安全使用提供依据。方法以具有代表性的水生动物斑马鱼为试验材科,采用静态法在室内测定水溶性塑料薄膜对斑马鱼的急性毒性并对其进行安全评价。结果斑马鱼的24、48和96 h半数致死浓度(LC50)分别为2.75%、2.20%和2.20%。结论水溶性塑料薄膜对斑马鱼有较强的毒性,应加强对其使用的管理。该研究为其安全使用提供了科学依据。     

Chronic ecotoxicity of copper and cadmium to the zebra mussel Dreissena polymorpha

In order to evaluate ecological consequences of the long-term presence of metals in aquatic ecosystems, we investigated the filtration rate and survival of zebra mussels (Dreissena polymorpha) during chronic exposure to Cu and Cd. The filtration rate was measured once a week in laboratory experiments lasting 9–11 weeks. The lowest Cu concentration tested (13 g/L) did not affect the filtration rate and survival of D. polymorpha, but the lowest Cd concentration (9 g/L) did affect the filtration rate, but had no effect on survival. The EC₅₀ for Cd decreased markedly from 388 g/L to 27 g/L when the exposure time was lengthened from 48 hours to 10 weeks. The largest decrease in EC₅₀ for Cd was observed during the first week of exposure. In contrast, the EC₅₀ for Cu did not decrease with increasing exposure time (chronic EC₅₀: 43 g/L). Since the chronic LC₅₀ for Cd was 130 g/L, the filtration rate appeared to be a far more sensitive endpoint for ecotoxicological laboratory experiments than mortality. D. polymorpha was capable of regulating the body concentration of the essential metal Cu at low concentrations in the water (13 g/L). Cd was accumulated at every Cd concentration in the water, suggesting that Cd could not be regulated by D. polymorpha. It is concluded that the relation between short-term and long-term ecotoxicity was different for each metal and could not be predicted from the results of the short-term experiments.     

Application of a Biomarker Response Index for Ranking the Toxicity of Five Pharmaceutical and Personal Care Products (PPCPs) to the Bivalve Dreissena polymorpha

Pharmaceuticals and personal care products (PPCPs) have been detected in several aquatic ecosystems during the last two decades, but their potential for biological effects to nontarget organisms is only now being studied. The aim of this study was to compare and rank the cyto-genetic effects induced by 96-hour exposure to an environmental concentration (1 nM) of triclosan (TCS), trimethoprim (TMP), diclofenac (DCF), ibuprofen (IBU), and paracetamol (PCM) on the freshwater bivalve Dreissena polymorpha by integrating biological responses of eight biomarker into a simple biomarker response index (BRI). The application of the BRI decreased the wide biomarker variability and enabled toxicity ranking of the tested PPCPs as follow: TCS > TMP > IBU > DCF = PCM. This approach allowed us to draw an accurate PPCP scale of toxicity of the most dangerous drug and to address further in-depth investigations.     

Chronic effects induced by ibuprofen on the freshwater bivalve Dreissena polymorpha

The sub-lethal effects induced by the non-steroidal anti-inflammatory drug ((NSAID) ibuprofen (IBU; ((±)-2-(p-isobutylphenyl) propionic acid))) were investigated using a battery of biomarkers on the freshwater bivalve Dreissena polymorpha. According to the results from a semi-static in vivo approach, mussels were exposed for 96 h to increasing levels of environmentally relevant IBU concentrations (0.2, 2 and 8 μg/l, corresponding to 1, 9 and 35 nM, respectively). Cyto-genotoxicity was evaluated via the single cell gel electrophoresis (SCGE) assay, the DNA diffusion assay, the micronucleus test (MN test) and lysosome membrane stability (Neutral Red Retention Assay) in mussel hemocytes. In addition, the activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and the phase II detoxifying enzyme glutathione S-transferase (GST) were measured in the cytosolic fraction that was extracted from a pool of entire bivalves to determine whether the oxidative status was imbalanced. The biomarker battery pointed out a slight cyto-genotoxicity on zebra mussel hemocytes at the IBU concentration of 0.2 μg/l, with higher IBU concentrations able to significantly increase both genetic and cellular damage. In addition, IBU seems to have a considerable effect on the activities of antioxidant and detoxifying enzymes as shown in the exposed specimens' notable oxidative status imbalances.     

Modeling metal bioaccumulation in the invasive mussels Dreissena polymorpha and Dreissena rostriformis bugensis in the rivers Rhine and Meuse

The metal-specific covalent index and the species-specific size-based filtration rate were integrated into a biokinetic model estimating metal bioaccumulation in mussels from the dissolved phase and phytoplankton. The model was validated for zebra (Dreissena polymorpha) and quagga (Dreissena rostriformis bugensis) mussels in the rivers Rhine and Meuse, the Netherlands. The model performed well in predicting tissue concentrations in different-sized zebra mussels from various sampling sites for (55) Mn, (56) Fe, (59) Co, (60) Ni, (82) Se, (111) Cd, (118) Sn, and (208) Pb (r(2) =0.71-0.99). Performance for (52) Cr, (63) Cu, (66) Zn, (68) Zn, and (112) Cd was moderate (r(2) <0.20). In quagga mussels, approximately 73 to 94% of the variability in concentrations of (82) Se, (111) Cd, (112) Cd, and (208) Pb was explained by the model (r(2) =0.73-0.94), followed by (52) Cr, (55) Mn, (56) Fe, (60) Ni, and (63) Cu (r(2) =0.48-0.61). Additionally, in both zebra and quagga mussels, average modeled concentrations were within approximately one order of magnitude of the measured values. In particular, in zebra mussels, estimations of (60) Ni and (82) Se concentrations were equal to 51 and 76% of the measurements, respectively. Higher deviations were observed for (52) Cr, (59) Co, (55) Mn, (56) Fe, (111) Cd, (63) Cu, and (112) Cd (underestimation), and (66) Zn, (68) Zn, (208) Pb, and (118) Sn (overestimation). For quagga mussels, modeled concentrations of (66) Zn and (68) Zn differed approximately 14% from the measured levels. Differences between predictions and measurements were higher for other metals.     

Lysosomal responses in the digestive gland of the freshwater mussel, Dreissena polymorpha, experimentally exposed to cadmium

In order to examine the possible use of lysosomal response as a biomarker of freshwater quality, structural changes of lysosomes were measured by image analysis in the digestive gland of the zebra mussel, Dreissena polymorpha, exposed in laboratory conditions to cadmium. Mussels were exposed to the metal (10 and 200 microg/L) for 3 weeks and randomly collected after 7 and 21 days. At each treatment day, digestive tissues were excised and beta-glucuronidase activity was revealed in cryotome sections. Four stereological parameters were calculated: lysosomal volume density, lysosomal surface density, lysosomal surface to volume ratio, and lysosomal numerical density. The changes observed in this study reflected a general activation of the lysosomal system, including an increase in both the number and the size of lysosomes in the digestive gland cells of mussels exposed to cadmium. The digestive lysosomal response in zebra mussels was related to exposure time and to metal concentration, demonstrating the potential of this biomarker in freshwater biomonitoring.     

Acute toxicity tests and pulsed-dose delayed mortality at 12 and 22°C in the zebra mussel (Dreissena polymorpha)

Three potential chemical controls (sodium hypochlorite, hydrogen peroxide, and poly[oxyethylene (dimethylimino) ethylene (dimethylimino) ethylene dichloride] (commercial trade name BULAB 6002)) were evaluated for acute toxicity to small adult zebra mussels (Dreissena polymorpha) in chronic and pulsed-dose laboratory trials at two temperatures. All three control agents tested effected greater mortality ofD. polymorpha at 22°C than at 12°C. In most cases the mortality level at 12°C was one half or less that incurred at the higher temperature. Analysis of variance showed significant effects of temperature in the case of BULAB 6002 and for hydrogen peroxide; plots of cumulative mortality through time show this trend as well. The relationship between mussel valve length and time-of-death is consistently positive but is significant in few individual treatments, however, when treatments (all concentrations and temperatures) for a single biocide are pooled, the relationship is significant and explains 16–26% of the variance. This suggests that control programs might be more effective if they are initiated whenD. polymorpha are small. Pulsed-dose control programs also are affected by temperature but generally are likely to be more cost-effective than continuous application control programs and would result in lower overall discharge of biocides to surface waters. Hydrogen peroxide at concentrations of 12.0, 20.0, or 30.0 mg/L is a quick acting control agent that probably will have fewer long-term consequences for nontarget organisms in discharge areas or for municipal water users than either BULAB 6002 or, especially, sodium hypochlorite.     

Toxicity of Synthetic Musks to Early Life Stages of the Freshwater Mussel Lampsilis cardium

Polycyclic musk fragrances are common additives to many consumer products. As a result of their widespread use and slow degradation rates, they are widely found in aquatic environments. This study reports on the lethal and sublethal toxicity of the polycyclic musks AHTN (Tonalide) and HHCB (Galaxolide) to glochidial (larval) and juvenile life stages of the freshwater mussel Lampsilis cardium (Rafinesque, 1820). In glochidia, 24-h median lethal concentrations (LC50s) ranged from 454 to 850 microg AHTN/L and from 1000 to >1750 microg HHCB/L (water solubility). Results for 48-h tests were similar to the 24-h tests. In 96-h tests with juveniles, we did not observe a dose-response relation between mortality and either musk. However, the growth rate was reduced by musk exposure. The median effective concentrations (EC50s, based on growth) were highly variable and ranged from 108 to 1034 microg AHTN/L and 153 to 831 microg HHCB/L. While all adverse effects occurred at concentrations that are much greater than those reported in natural waters (low microg/L to ng/L), these results indicate the potential for adverse effects on these long-lived organisms from exposure to synthetic musk fragrances.