Subchronic Toxic Effects of Fluoride Ion on the Survival and Behaviour of the Aquatic Snail <Emphasis Type="Italic">Potamopyrgus antipodarum</Emphasis> (Hydrobiidae,Mollusca)

Short-term bioassays usually assess lethal effects of pollutants in animals, whereas subchronic bioassays are more suited for assessing effects on animal behaviour. Among them, videotaped bioassays are an improvement in the behavioural monitoring because they are easily and cheaply implemented. The present study focuses on the assessment of subchronic (14-day) effects of fluoride ion on the survival, proportion of dead plus immobile animals, and velocity (monitored by a videotaping and image analysis system) of the aquatic snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca). One control and three nominal fluoride concentrations (5, 20, and 40 mg F⁻/l [actual mean concentrations of 5.2, 17.5, and 37.0 mg F⁻/l, respectively]) were used. Each treatment (including the control) was replicated 12 times. Mortality, number of dead plus immobile animals, and velocity were monitored after 0, 7, and 14 days of exposure. After 14 days, animals exposed to 40 mg F⁻/l showed higher mortality, number of dead, and immobile individuals than control animals. Snails exposed to 5 and 20 mg F⁻/l were not affected by fluoride ion regarding these endpoints. In contrast, snails exposed to 20 mg F⁻/l for 7 and 14 days showed lower velocity than control animals. Therefore, velocity was sensitive to environmental fluoride concentrations and as such is a useful parameter for ecologic risk assessment. In addition, videotaping allowed us to detect behavioural patrons in velocity at very short exposures (seconds) during the monitoring process by showing that the velocity of snails must be monitored at least during the course of several minutes. We conclude that in P. antipodarum, velocity is a more sensitive endpoint than the classic mortality and immobility endpoints.     

Toxicological Assessment of Ammonia Exposure on Carassius auratus red var. Living in Landscape Waters

To understand the toxic mechanism of ammonia and identify effective biomarkers on the oxidative stress for the fish Carassius auratus red var., acute and chronic toxicity tests were conducted. The 96-h LC₅₀ of total ammonia nitrogen (TAN) for C. auratus was 135.4 mg L⁻¹, the corresponding unionized ammonia (NH₃) concentration was 1.5 mg L⁻¹. The activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), glutathione-peroxidase (GSH-Px) and glutathione (GSH) showed an increase with a subsequent falling, while the malondialdehyde (MDA) increased during the chronic test. The SOD, MDA, and GSH could be effective biomarkers to evaluate the TAN oxidative stress, the maximum acceptable toxicant concentration (MATC) was 11.3 mg L⁻¹ for TAN. To our knowledge, this is the first study to propose biomarkers to evaluate potential environmental risk and establish a risk threshold for TAN in C. auratus.

     

Acute and chronic aquatic toxicity of ammonium perfluorooctanoate (APFO) to freshwater organisms

Recent concerns have been raised concerning the widespread distribution of perfluorinated compounds in environmental matrices and biota. The compounds of interest include ammonium perfluorooctanoate (APFO, the ammonium salt of perfluorooctanoic acid, PFOA). APFO is used primarily as a processing aid in the production of fluoropolymers and fluoroelastomers. The environmental presence of perfluorooctanoate (PFO⁻, the anion of APFO) and its entry into the environment as APFO make quality aquatic toxicity data necessary to assess the aquatic hazard and risk of APFO. We conducted acute and chronic freshwater aquatic toxicity studies with algae, Pseudokirchneriella subcapitata, the water flea, Daphnia magna, and embryo-larval rainbow trout, Oncorhynchus mykiss, using OECD test guidelines and a single, well-characterized sample of APFO. Acute 48–96 h LC/EC₅₀ values were greater than 400 mg/l APFO and the lowest chronic NOEC was 12.5 mg/l for inhibition of the growth rate and biomass of the freshwater alga. Un-ionized ammonia was calculated to be a potential significant contributor to the observed toxicity of APFO. Based on environmental concentrations of PFO⁻ from various aquatic ecosystems, the PNEC value from this study, and unionized ammonia contributions to observed toxicity, APFO demonstrates little or no risk for acute or chronic toxicity to freshwater and marine aquatic organisms at relevant environmental concentrations.     

Acute and chronic effects of testosterone and 4-hydroxyandrostenedione to the crustacean Daphnia magna

Steroid compounds have been globally detected in surface waters. The ecological impacts of these biologically active chemicals are largely unknown. Toxicity of testosterone and 4-hydroxyandrostenedione was assessed for the freshwater cladoceran Daphnia magna. Acute toxicity tests showed that 6.20 mg L⁻¹ of testosterone, the highest concentration tested, did not have effect on the daphnids, whereas 4-hydroxyandrostenedione had an EC₅₀ of 4.26 mg L⁻¹. Chronic toxicity tests were carried out using survival, body length, fecundity, and fertility as endpoints. Long-term testosterone exposure reduced D. magna fecundity and fertility at concentrations ranging from 0.31 to 2.48 mg L⁻¹. The significant decrease in fecundity was associated with an increase in aborted eggs. Long-term 4-hydroxyandrostenedione exposure at 0.84 mg L⁻¹ increased the mortality of the neonates. The chronic toxicity effects were observed at concentrations higher than the measured environmental concentrations of these compounds. Nevertheless, the reproductive impairment of the daphnids is likely to occur at environmental levels as an ultimate response to long-term exposure.     

Acute and Postexposure Effects of Ammonia Toxicity on Juvenile Barramundi (<Emphasis Type="Italic">Lates calcarifer</Emphasis> [Bloch])

Lethal and sublethal effects of ammonia toxicity to juvenile barramundi (Lates calcarifer) were investigated under laboratory conditions following the OECD guidelines for testing of chemicals. Acute toxicity was tested in a static nonrenewal system at pH 9.0 and temperature around 29°C. The 24-, 48-, and 96-h LC₅₀ values for barramundi were 3.89, 3.67, and 3.31 mg total ammonia N L⁻¹ and 1.59, 1.47, and 1.3 mg nonionized ammonia N L⁻¹, respectively. Estimated lethal concentrations indicated a relatively high sensitivity to acute ammonia toxicity for barramundi and equaled the 25th percentile most sensitive North American fish species with regard to the species mean acute value (USEPA 1999). A 3-week postexposure experiment on surviving individuals from the acute toxicity test, in clean water, indicated that exposure to acute concentrations up to 1.16 mg nonionized ammonia N L⁻¹ did not have any significant effects on growth.     

Toxicity of ammonia to nine native New Zealand freshwater invertebrate species

The toxic concentration for un-ionized ammonia (NH₃) was assessed for nine native New Zealand invertebrate species. The 96-h EC₅₀ values at 15°C and pH 7.6 and pH 8.2 ranged from 0.18 to >0.8 g/m³ NH₃. The rank of species sensitivity was: shrimp (Paratya curvirostris) (least) mayfly (Zephlebia dentata) stonefly (Zealandobius furcillatus) < Oligochaeta (Lumbriculus variegatus) < fingernail clam (Sphaerium novaezelandiae) < mayfly (Deleatidium spp.) < a snail (Potamopyrgus antipodarum) < caddis (Pycnocentria evecta) < crustacean (Paracalliope fluviatilis) (most). Surprisingly, the more sensitive species were those which would normally be associated with lowland streams (the snail and crustacean) rather than the normally accepted sensitive species (mayflies and stoneflies). Temperature had no significant effect on the acute toxicity of un-ionized ammonia with snails tested at 15, 20, and 25°C. The invertebrates were more sensitive than the native fish species tested (inanga, EC₅₀ 1.60 g/m³ NH₃; Richardson 1991). A final acute value (FAV) calculated for these species was 0.15 g/m³ NH₃. This compares with the FAV value of 0.52 g/m³ NH₃ derived by the US Environmental Protection Agency (EPA) as the basis for the ammonia criterion for salmonid containing waters. Thus EPA criteria may not provide adequate protection for New Zealand species. These data suggest that chronic studies would be particularly desirable on native New Zealand species to better determine their sensitivity to long term ammonia exposure.     

Effects of Nitrite and Toxic <Emphasis Type="Italic">Microcystis Aeruginosa</Emphasis> PCC7806 on the Growth of Freshwater Rotifer <Emphasis Type="Italic">Brachionus Calyciflorus</Emphasis>

Over the last two centuries, anthropogenic activities have increased the nitrogen amount in aquatic ecosystems, which has resulted in increased occurrences of blooms of cyanobacteria. This study investigated the effects of nitrite and the cyanobacterium Microcystis aeruginosa on population growth in the rotifer Brachionus calyciflorus. The rotifer was treated for 12 days with nitrite alone (medium containing 0, 3, 6, 10 mg NO₂ ⁻ –N L⁻¹), M. aeruginosa alone (medium containing 0 mg NO₂ ⁻–N L⁻¹ + 5.0 × 10⁵ cell ml⁻¹ M. aeruginosa precultured at 0, 3, 6, 10 mg NO₂ ⁻–N L⁻¹), and nitrite in combination with M. aeruginosa (medium containing 3, 10 mg NO₂ ⁻–N L⁻¹ + 5.0 × 10⁵ cell ml⁻¹ M. aeruginosa precultured at corresponding nitrite concentrations). We observed that a nitrite concentration of 10 mg NO₂ ⁻–N L⁻¹ markedly inhibited the growth of B. calyciflorus; however, rotifer growth declined slightly in the presence of M. aeruginosa precultured at 6 mg NO₂ ⁻–N L⁻¹. Furthermore, reduced population growth of B. calyciflorus was observed when it was treated with both nitrite and M. aeruginosa compared to nitrite alone or M. aeruginosa alone. These results suggested that a high tolerance of B. calyciflorus to nitrite levels may be attributed to the absence of specific respiratory structures and pigments; and that the increased toxicity of nitrite in combination with M. aeruginosa may have been due to increased production of microcystin. It is also possible that nitrite and microcystin could act in a synergistic way in causing toxicity.     

Long-Term Toxicity of Gadolinium to the Freshwater Crustacean Daphnia magna

The lanthanides are considered emerging contaminants but information on their long-term toxicity to aquatic species under environmentally relevant conditions is scarce. We aimed to fill this gap by evaluating the long-term adverse effects of gadolinium on the freshwater model—crustacean Daphnia magna. The exposure of D. magna for up to 39 days to 0.1 mg Gd/L (a 21-days chronic toxicity NOEC value derived by us formerly) in the lake water had no negative effect (p?>?0.05) on vitality, size and reproduction of parent animals as well as their offspring. Thus, assumingly the current Gd contamination levels of surface waters pose no hazard to aquatic crustaceans that in general are very sensitive to various pollutants. Moreover, presence of 0.1 mg Gd/L in the lake water even mitigated the long-term toxic effect of 0.2 mg Ni/L (studied as a model co-contaminant) to D. magna’s vitality and productivity.

     

Physiological Stress of High NH<Stack><Subscript>4</Subscript><Superscript>+</Superscript></Stack> Concentration in Water Column on the Submersed Macrophyte <Emphasis Type="Italic">Vallisneria Natans</Emphasis> L.

The submersed macrophyte, Vallisneria natans L., was cultured in laboratory with NH₄⁺-enriched tap water (1 mg L⁻¹ NH₄-N) for 2 months and the stressful effects of high ammonium (NH₄⁺) concentrations in the water column on this species was evaluated. The plant growth was severely inhibited by the NH₄⁺ supplement in the water column. The plant carbon and nitrogen metabolisms were disturbed by the NH₄⁺ supplement as indicated by the accumulation of free amino acids and the depletion of soluble carbohydrates in the plant tissues. The results suggested that high NH₄⁺ concentrations in the water column may hamper the restoration of submersed vegetation in eutrophic lakes.     

Contrasting Sensitivities to Fluoride Toxicity between Juveniles and Adults of the Aquatic Snail <Emphasis Type="Italic">Potamopyrgus antipodarum</Emphasis> (Hydrobiidae,Mollusca)

In contrast to aquatic vertebrates, there is scarce available information on the contrasting tolerance to fluoride of different life stages and/or sizes of aquatic invertebrates. The purpose of this study was to assess the likely differences in sensitivity between juveniles and adults of the aquatic snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca) to short-term (4 days) toxicity of fluoride ion (F⁻). LC50 and EC50 values for juveniles were significantly lower than those for adults at 24, 48, 72 and 96 h. Based on our results, the use of fluoride data of bioassays with juveniles should provide more protective water quality criteria than data from adult stage.     

Effects of Nutrient Pre-Exposure on Atrazine Toxicity to Vallisneria americana Michx. (Wild Celery)

Accelerated eutrophication is common to many freshwater and marine environments and often co-occurs with the presence of anthropogenic chemicals. However, the toxic effects of common chemical stressors such as herbicides in the presence of elevated nutrients are not well understood for most aquatic flora, particularly vascular species. To provide insight, field-collected Vallisneria americana Michx. (wild celery) were sequentially exposed to three nutrient concentrations for 3 months and then to nominal 11 and 110 μg L⁻¹ atrazine for 96 h. Nutrient concentrations (combined NH₄ ⁺, NO₂ ⁻, NO₃ ⁻, PO₄ ⁻) were based on ambient concentrations in the St. Johns River (FL) and ranged from 0.013 to 0.668 mg L⁻¹. Nutrient pretreatment potentiated the toxicity of atrazine as determined by chlorophyll fluorescence activity. Electron transport rates (ETR) were significantly less (48–59%) for plants pretreated with low and ambient nutrient levels in the presence of an average of 107.5–128.1 μg L⁻¹ atrazine. Significant ETR reductions were also observed for plants exposed to an average of 11.4 μg L⁻¹ atrazine after exposure to nutrients three times the ambient concentration in the St. Johns River. The results indicate the importance of considering the presence of nutrients in chemical hazard assessments, particularly for phytotoxicants and nontarget vascular plants.     

Accumulation and Chronic Toxicity of Uranium Over Different Life Stages of the Aquatic Invertebrate <Emphasis Type="Italic">Chironomus tentans</Emphasis>

Limited data are available on the effects of uranium (U) exposures on benthic macroinvertebrates, something that would be needed before national or provincial water quality guidelines could be developed. The goal of this study was to evaluate chronic U toxicity and accumulation in the aquatic invertebrate Chironomus tentans. Test organisms were exposed to three aqueous U concentrations (40, 200, and 1,000 μg/L) and an untreated control. Larval growth, adult emergence, and U tissue concentrations at different life stages were evaluated. The measured no-observed-effect concentration (NOEC) and lowest-observed-effect concentration (LOEC) for growth of C. tentans larvae after 10 days of U exposure were 39 and 157 μg/L, respectively. At U concentrations >157 ug/L, there was reduced larval growth of 30% to 40%, which corresponded to reduced adult emergence of 40% to 60%. Despite significant delays in time to adult emergence, there were no significant effects on reproductive output of successfully emerged adults. The F₁ generation C. tentans larvae that were never directly exposed to U, but originated from adult males and females exposed to U during their immature life stages, displayed a significant decrease in 10-day growth that was similar to that observed for the F₀-exposed larvae. This suggests that the environment of the parental generation can significantly influence the development of the next generation through environmentally induced parental effects. Uranium accumulated in C. tentans immature stages was partially excreted during molting and metamorphosis to the adult stage. However, the elimination of U was not complete and some was still measured in adult midges. Consequently, a minor transfer of U from the aquatic to the terrestrial environment could be expected to occur.     

Assessment the Toxic Effects of Dimethoate to Rotifer Using Swimming Behavior

The toxic effects of the common organophosphorus pesticide dimethoate on freshwater zooplankton Brachionus calyciflorus (rotifer) were tested. Because of the advantages of behavioral response in environmental monitoring, swimming behavior was used as the endpoint in this research. After exposure 6 h at five dimethoate concentrations (0.18, 0.53, 0.88, 1.23 and 1.59 mg·L⁻¹), the pesticide disrupted the balance in rotifer swimming direction and caused an obvious direction preference. It also inhibited significantly the swimming angular and linear speed. Our results showed that dimethoate has a sublethal toxic effect on this aquatic invertebrate.     

Effects of the polycyclic musk HHCB on individual- and population-level endpoints in Potamopyrgus antipodarum

Although the polycyclic musk 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[γ]-2-benzopyran (HHCB) is frequently detected in aquatic sediments, very little is known about its effects on sediment-feeding organisms. Effects of sediment-associated HHCB on growth, feeding rate, survival and reproduction in the gastropod Potamopyrgus antipodarum were measured in the laboratory. Snails were exposed to six nominal HHCB concentrations: 0, 0.1, 1, 10, 30 and 100 μg g^?1 dry weight (dw) sediment. Adult survival and growth were not affected by HHCB. However, juvenile growth and survival, reproduction, time to first reproduction and adult feeding rate were more sensitive endpoints and declined with increasing HHCB concentration. Individual-level endpoints for P. antipodarum were integrated into a population model to investigate the effects of HHCB on population growth rate. Under otherwise favorable laboratory conditions, population growth rate was slightly (by ca. 2%), but not significantly, reduced with increasing HHCB exposure concentration. Model simulations were performed to explore the consequences of HHCB exposure under more ecologically realistic conditions (i.e., survival and reproduction of unexposed snails were markedly reduced relative to the laboratory). The results suggest that despite detectable effects of HHCB on individual-level endpoints measured in the laboratory, impacts on population dynamics of this deposit feeder are not likely to occur at environmentally relevant exposure concentrations.     

Quantitative Behavioral Parameters as Toxicity Biomarkers: Fish Responses to Waterborne Cadmium

The disruptive sublethal effects of heavy metals on behavioral parameters of fish as biomarkers of aquatic toxicity have been scarcely studied. We investigated the impact of exposure to sublethal waterborne cadmium on locomotory parameters of three freshwater teleosts: Cyprinus carpio as reference species, and Australoheros facetum (sin. Cichlasoma facetum) and Astyanax fasciatus, native to Pampean ecosystems in Argentina, using a noninvasive bioassay under laboratory conditions. Fish were successively transferred to media containing freshwater (control period), Cd²⁺ solutions (exposure period), and freshwater (recovery period). The behavioral biomarkers evaluated were swimming activity and swimming speed of fish. The metal provoked different responses of both parameters after 4–7 days of exposure; the reversibility of changes was also assessed. It was concluded that: (a) locomotion parameters are sensitive endpoints and useful biomarkers in behavioral studies of freshwater toxicity, (b) the applied bioassay could be a valuable tool in water quality monitoring, and (c) the studied species differed in their susceptibility to the toxicant as well as in their capacity to return to basal values.     

Toxicity of Phenanthrene in Freshwater Sediments to the Rooted Submersed Macrophyte, <Emphasis Type="Italic">Vallisneria spiralis</Emphasis>

A study was conducted to determine the response of the rooted submersed macrophyte, Vallisneria spiralis to phenanthrene in freshwater sediments with initial phenanthrene concentrations from 0 to 80 mg kg⁻¹ dry sediment. The sensitivity of various morphological endpoints was evaluated after 90 days of exposure. The most sensitive toxicity test endpoints were those that reflected root growth. Toxicological sensitivity of the endpoints changed with the effect level selected. The toxicity threshold from a plot of the EC₁₀ values was 1–2 orders of magnitude lower than those calculated for the threshold from plots of the EC₂₅ or EC₅₀ values. In addition, stimulatory responses (hormesis) on root growth were observed at subtoxic concentrations of phenanthrene, and a hormetic model should thus be incorporated for ecological risk assessment.     

Effects of Pharmaceuticals on Aquatic Invertebrates. Part I. The Antiepileptic Drug Carbamazepine

The effects of the antiepileptic drug carbamazepine (CBZ) were studied in three freshwater invertebrate species representing different taxonomic groups, life histories, and habitats in aquatic ecosystems. The oligochaete Lumbriculus variegatus was exposed by way of CBZ-spiked sediments at nominal concentrations between 0.625 and 10 mg/kg dry weight (dw) for 28 days. At the end of the test, reproduction and biomass were monitored as end points. The nonbiting midge Chironomus riparius was exposed to CBZ in a series of tests at nominal CBZ concentrations in sediment ranging from 0.16 to 100 mg/kg dw at 20°C and 23°C. Emergence and gender ratio were monitored at the end of the test. The freshwater snail Potamopyrgus antipodarum as the third test species was used in a chronic reproduction test for 28 days at aqueous CBZ concentrations from 0.4 to 250 mg/L. Whereas for the oligochaete and the snail no effects were observed, C. riparius exhibited a significant and concentration-dependent decrease of emergence in all test series. No observed effect concentrations and 10% effect concentrations were in the range of 33 to 140 and 70 to 210 μg/kg dw, respectively, based on measured CBZ concentrations in sediments. These low values indicate that CBZ may pose a potential threat for the survival of C. riparius and probably also for other aquatic insect populations in the field.     

Effects of Cypermethrin (Pyrethroid Insecticide) on the Valve Activity Behavior,Byssal Thread Formation,and Survival in Air of the Marine Mussel <Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis>

Cypermethrin is a pyrethroid pesticide widely used to combat agricultural pests. However, little information is available about its toxicity in aquatic macroinvertebrates in the context of the Moroccan coastline. In this study, a suite of physiological and behavioral biomarkers for water quality surveillance using mussels are used to characterize the toxicity of Cypermethrin. In these tests, sublethal effects on valve activity behavior, byssal thread formation, and survival in air of the mussel Mytilus galloprovincialis were assessed in short-term exposure. The results show that Cypermethrin impaired the valve activity in a concentration-dependent manner, leading to a reduction in the time of normal opening. The lowest effect concentration was determined as 100 μg/l Cypermethrin. Prolonged closures of mussels were also observed for the exposures to 400 and 800 μg/l. The delay to the first detection of the pesticide was concentration dependent. The capacity to produce new byssus threads in a Cypermethrin exposure was inhibited at all concentrations and especially at high concentrations. Survival in air was not affected even at 800 μg/l Cypermethrin.     

The toxicity of waterborne boron toDaphnia magna andChironomus decorus and the effects of water hardness and sulfate on boron toxicity

The concentrations of many elements, including boron, are increasing in aquatic ecosystems due to anthropogenic activities. Laboratory studies were undertaken to evaluate the toxicity of waterborne boron to two key fresh water macroinvertebrates and to evaluate the effects of water hardness and sulfate on boron toxicity. Acute toxicity evaluations of waterborne sodium tetraborate resulted in 48 h. LC₅₀ values of 141 and 1376 mg B/L for neonateDaphnia magna and fourth instarChironomus decorus, respectively. Chronic sublethal studies demonstrated a significant decrease inC. decorus growth rate at 20 mg B/L. Further studies showed that increasing water hardness (10.6 to 170 mg/L as CaCO₃) and sulfate (10.2 to 325.4 mg SO₄ ^–1/L) concentrations did not affect boron toxicity toD. magna. These results, in conjunction with a review of the literature, suggest that aquatic macrophytes may be more sensitive to boron than macroinvertebrates and thus would be better choices for aquatic risk assessment evaluations for this element.     

Toxicity of Ammonia Nitrogen to Ciliated Protozoa <Emphasis Type="Italic">Stentor coeruleus</Emphasis> and <Emphasis Type="Italic">Coleps hirtus</Emphasis> Isolated from Activated Sludge of Wastewater Treatment Plants

We assessed the toxicity of ammonia ions to Stentor coeruleus and Coleps hirtus (Protozoa) isolated from activated sludge taken from two municipal wastewater treatment plants in southern Poland. Stentor coeruleus is a rarely occurring species in activated sludge, unlike the widespread Coleps hirtus. The mean LC50 values (concentration causing 50 % mortality) calculated for the 24 h tests differed hugely between the tested species: 43.03 mg NH⁴⁺ dm⁻³ for Stentor coeruleus and 441.12 mg NH⁴⁺ dm⁻³ for Coleps hirtus. The ammonia ion concentration apparently is an important factor in the occurrence of these protozoan species in activated sludge.