Effects of water hardness, water temperature, and size of the test organism on the susceptibility of the freshwater shrimp, Gammarus pulex (L.), to toxicants

Ecotoxicity of phenol and cresols to aquatic organisms: A review

With the development of industrial production and continuous demand for chemicals, a large volume of wastewater containing phenols was discharged into the aquatic environment. Moreover, chemical leakage further increased the emission of phenols into aquatic systems. Phenol and its methylated derivative (cresols) were selected due to their extensive use in industry and ecotoxicity to freshwater and marine organisms. This review focused on the ecotoxicity of phenol and m-, o-, and p-cresol on aquatic systems. The mechanism of action of phenols was also discussed. The aim of this literature review was to summarise the knowledge of the behaviour, and toxicity on marine and freshwater organisms, of phenols as well as to try to select a series of sensitive biomarkers suitable for ecotoxicological assessment and environmental monitoring in aquatic environments.

Unexpected toxic interactions in the freshwater amphipod Gammarus pulex (L.) exposed to binary copper and nickel mixtures

To document the toxicity of copper and nickel in binary mixtures, freshwater amphipods Gammarus pulex were exposed to the metals given independently or as mixtures. Toxicity to Cu alone was relatively high: 96-h LC10 and LC50 were found at 91 and 196 μg L(-1), respectively. Toxicity to Ni alone was very low, with 96-h LC10 and LC50 of 44,900 and 79,200 μg L(-1), respectively. Mixture toxicities were calculated from single toxicity data using conventional models. Modeled toxicity was then compared with the measured toxicity of the binary mixture. Two kinds of mixtures were tested. Type I mixtures were designed as combinations of Cu and Ni given at the same effect concentrations, when taken independently, to identify possible interactions between copper and nickel. In type II mixtures, Cu concentrations varied from 0 to 600 μg L(-1) while the nickel concentration was kept constant at 500 μg L(-1) to mimic conditions of industrial wastewater discharges. Ni and Cu showed synergic effects in type I mixtures while type II mixtures revealed antagonistic effects. Low doses of Ni reduced Cu toxicity towards G. pulex. These results show that even for simple binary mixtures of contaminants with known chemistry and toxicity, unexpected interactions between the contaminants may occur. This reduces the reliability of conventional additivity models.

Assessment of physicochemical parameters of wastewater samples

Water samples from selected locations of Nullah Lai and Koh-e-Noor textile mill in the metropolitan city of Rawalpindi and Islamabad, Pakistan, were collected. Physicochemical parameters and heavy metals were determined using standard analytical procedures in comparison with sites, locations and subsequent interval of 3 months. The results of the physicochemical analysis at different locations of Nullah Lai and Koh-e-Noor textile mill with an interval of 3 months were obtained in the following range: pH (7.16-8.29), temperature (17.8-28.8 °C), conductivity (1,005-3,347 μS/m), TDS (754.3-2,519.5 mg/L), turbidity (272.8-487.05 NTU), total hardness (300-452 mg/L), nitrates (10.11-22.95 ppm), calcium (74.31-139.2 ppm), chloride (127.72-396.16 ppm), sulphate (15.97-87.38 ppm), NaCl (210.5-631.1 ppm), Ni (0.30-0.72 ppm), Cd (0.005-0.03 ppm), Cr (0.2-7.4 ppm), Pb (0.12-0.73 ppm), Zn (0.03-0.08 ppm) and Cu (0.01-0.06 ppm). The highest value of physicochemical parameters (compared with Nullah Lai) was obtained in locations of Koh-e-Noor textile mill. The results obtained exceeded the maximum allowable limit set by the World Health Organization for drinking purpose but can be used for irrigation purposes after suitable treatment and purification.

Closer to reality--the influence of toxicity test modifications on the sensitivity of Gammarus roeseli to the insecticide imidacloprid

Laboratory toxicity test designs are far from reality and therefore extrapolations to field situations may be more difficult. In laboratory experiments with the amphipod Gammarus roeseli exposed to the insecticide imidacloprid it was investigated if test conditions closer to reality influences its sensitivity and if it is possible to extrapolate results from these laboratory tests to results from a stream mesocosm study. Experiments were run by varying medium, temperature, size, and seasonal origin of gammarids. Age and seasonal aspects had strongest effects with juveniles and animals taken from a spring population being most sensitive with an EC₅₀ (96 h) of 14.2 μg L⁻¹ imidacloprid. The test designs closest to the conditions in the stream mesocosms reflected best the results in mesocosms study on basis of LOEC values. However, the EC(x) extrapolation failed to predict the effects of short term imidacloprid pulses in the field.

A freshwater amphipod toxicity test based on postexposure feeding and the population consumption inhibitory concentration

Consumption inhibition in natural populations, namely due to contaminants, may have direct and immediate effects on ecosystems, by hampering ecosystem key functions (e.g., organic matter decomposition, grazing), long before effects at the individual level (e.g., reproduction, growth, emergence) have time-delayed consequences at successively higher levels of biological organization. The present study aimed at developing a cost-effective (short and easy) toxicity test based on the postexposure feeding of a freshwater amphipod present in the Iberian Peninsula and at evaluating the immediate impact of contamination on the population-level consumption rate. First, methodologies to quantify postexposure feeding were developed and optimized, the most important criterion being a feeding period as short as possible to minimize physiological recovery from the contaminant exposure. Second, the sensitivities of 48-h postexposure feeding and 48-h lethality tests were compared, using a reference chemical - copper. Third, the latter responses were integrated in a single parameter, the median population consumption inhibitory concentration. When Echinogammarus meridionalis males were fed on 100 defrosted Artemia franciscana nauplii during 30 min in darkness at 19-21°C, the eaten proportion was approximately 80%, without truncated data distributions. The 48-h median effective copper concentration for postexposure feeding was approximately two times lower than the 48-h LC50 - 91 versus 198 μg L(-1), respectively. Two techniques were used to quantify the median population consumption inhibitory copper concentration, both leading to similar values (75 and 68 μg L(-1)). In conclusion, when contaminant concentrations elicit both lethality and feeding depression, the integration of both responses can provide an ecologically relevant evaluation on the potency of a contaminant to immediately disrupt ecosystem functioning.

Acute toxicity of organic chemicals to Gammarus pulex correlates with sensitivity of Daphnia magna across most modes of action

We investigated the sensitivity of the freshwater crustacean amphipod Gammarus pulex towards organic xenobiotic compounds in comparison to the sensitivity of the crustacean cladoceran Daphnia magna. In addition we studied the influence of the chemical's mode of action on the relationship between the sensitivity of G. pulex and that of D. magna. We tested the acute toxicity of twelve compounds (Malathion, Aldicarb, Carbofuran, 2,4-dichloroaniline, 2,4-dichlorophenol, 1,2,3-trichlorobenzene, 4,6-dinitro-o-cresol, 2,4,5-trichlorophenol, Ethylacrylate, 4-nitrobenzyl-chloride, Sea-nine, Imidacloprid) with different modes of action and physicochemical properties towards the freshwater amphipod G. pulex in laboratory experiments. Additional toxicity data was collected from the peer-reviewed literature and databases (data pairs for 44 chemicals in total). The chemicals were assigned to seven mode of action groups. The relationship between the sensitivity of G. pulex (48h-LC50s and 96h-LC50s) and that of D. magna (48h-EC50s) was investigated using regression analysis and correlation plots. G. pulex is two to three orders of magnitude more sensitive towards neonicotinoids than D. magna (P=0.0046, n=3). For organophosphates we found that D. magna is more sensitive than G. pulex by approximately a factor of six (P=0.0256, n=6). There was no significant difference between the sensitivity of D. magna and that of G. pulex in any of the other mode of action groups; however chemicals with the same mode of action grouped together in the same area of the correlation plot. Without the neonicotinoids 75% of all G. pulex toxicity data were within one order of magnitude of the D. magna data and 100% within two orders of magnitude. The regressions with all data and with all data minus neonicotinoids were both significant linear relationships with slopes around one and intercept around zero. Thus, G. pulex is generally equally sensitive towards organic xenobiotics as D. magna.

Determination of EC50 toxicity data of selected heavy metals toward Heterocypris incongruens and their comparison to "direct-contact" and microbiotests

The sensitivity of Heterocypris incongruens to selected heavy metal ions is discussed. Although the Ostracodtoxkit ® has been present on the market for a few years, data on its selectivity and sensitivity to toxicants is scarce; such data is indispensable when interpreting the results of sediment toxicity. The LC(50) and EC(50) results with the Ostracodtoxkit ® are compared with those obtained with other commercially available "direct-contact" tests (utilizing Hyalella azteca and Chironomus riparius) and microbiotests for assessing the toxicity of aqueous samples (Vibrio fischeri, Daphnia magna, and Selenastrum capricornatum). The sensitivity of H. incongruens to metal ions (Cd(2+)> >Hg(2+)> Cu(2+)>Cr(6+ )>Ni(2+) ≈ Mn(7+)>Zn(2+)>Pb(2+)>Li(1+ )> Fe(3+)) was found to be similar to that of H. azteca and of C. riparius. The Ostracodtoxkit ® has shown itself to be an efficient and reliable element of test batteries for toxicity determination.

High sensitivity of Gammarus sp. juveniles to deltamethrin: outcomes for risk assessment

Amphipods from the genus Gammarus are among the most frequently used organisms in ecotoxicological testing and in situ bioindication. Because of their importance in risk assessment, it is necessary to understand the potential roles of life stage, population source and inter-specific differences on the sensitivity of these organisms to contaminants. In the present study, the acute toxicity of deltamethrin, a commonly used pyrethroid insecticide, has been tested for Gammarus fossarum and Gammarus pulex (Crustacea, Amphipoda) to document the inter- and intra-specific variability at different developmental stages. Adult G. fossarum were about two-fold more sensitive to deltamethrin than adult G. pulex, 96-h LC50 being 33.2 and 68.0 ng L(-1), respectively. However, in the same species, significant differences of sensitivity were observed between individuals from different locations. Furthermore, G. fossarum from certain localities were less sensitive to deltamethrin than certain G. pulex. In addition, juveniles of both species were about 14- to 22-fold more sensitive to deltamethrin than adults: 48-h LC50 in G. fossarum and G. pulex juveniles were 4.0 and 5.7 ng L(-1). Therefore, lethal effects of deltamethrin on Gammarus sp. populations likely depend more on juvenile response rather than on adult response. Since juveniles were also the most abundant population component, the present results show that risk assessment should consider at this developmental stage.

Assessing the performance of a bdelloid rotifer Philodina acuticornis odiosa acute toxicity assay

A bioassay using the bdelloid rotifer, Philodina acuticornis odiosa, was evaluated for use as a standard test method for direct toxicity assessment testing in the Australasian region. Philodina acuticornis odiosa was found to be relatively tolerant to phenol (24 h LC50, 142 mg/L). The mortality endpoint was both reliable and repeatable (the coefficients of variation for mortality at the 24 h LC50 concentration ranged from 11%-24% (n = 8)), sufficiently low to warrant further testing with a range of reference toxicants, so that this organism can be included for use as a regulatory test in Australasia.

Mixture toxicity assessment of wood preservative pesticides in the freshwater amphipod Gammarus pulex (L.)

All over the world, insecticides and fungicides are used to protect wood against pathogens. To document the environmental toxicity of wood preservative mixtures, freshwater amphipods Gammarus pulex (L.) were submitted to organic pesticides given independently or in mixtures. When given independently at environmentally realistic concentrations, propiconazole and tebuconazole (triazoles fungicides) were not toxic for G. pulex, 3-iodo-2-propinyl butyl carbamate (IPBC, fungicide) was moderately toxic, and cypermethrin (pyrethroid insecticide) was extremely toxic. 96-h LC50 were, respectively, 4703, 1643, 604, and 0.09 microg L(-1). When amphipods were submitted to a mixture mimicking the composition of a commercial solution (18.2% of cypermethrin, 45.8% propiconazole, 17.2% tebuconazole, 18.8% IPBC), the overall toxicity was equal to that of the most toxic component, namely cypermethrin. But, when organisms were submitted to the real commercial mixture containing pesticides, solvents and additives, the toxic effects were markedly higher. Moreover, a third mixture with only 0.002% cypermethrin showed lethality 2.5-18-fold higher than those predicted by the commonly used models. The present results show that toxicity of wood preservative mixtures cannot be assessed starting only from the toxicities of each single component. Furthermore, the present data strongly suggest that the environmental impacts of wood preservative mixtures might be frequently underestimated.

Trend in metals variation in Tasik Chini, Pahang, Peninsular Malaysia

Water from 15 sampling stations in Tasik Chini (Chini Lake), Peninsular Malaysia were sampled for 12 months from September 2004 until August 2005 and analyzed for 11 metals including iron (Fe), aluminum (Al), manganese (Mn), barium (Ba), zinc (Zn), lead (Pb), copper (Cu), cadmium (Cd), nickel (Ni), chromium (Cr) and cobalt (Co). Results showed that the mean (min-max) metal concentrations (in micrograms per liter) in Tasik Chini waters for the 12 months sampling based on 15 sampling stations (in descending order) for Fe, Al, Mn, Ba, Zn, Pb, Cu and Cd were 794.84 (309.33-1609.07), 194.53 (62.37-665.93), 29.16 (16.68-79.85), 22.07 (15.64-29.71), 5.12 (2.224-6.553), 2.36 (1.165-4.240), 0.832 (0.362-1.443) and 0.421 (0.254-0.696) respectively. Concentration for three metals i.e. Ni, Cr and Co were too low and not detected by the graphite furnace Atomic Absorption Spectrophotometry (AAS). Comparison with various water quality standards showed that the mean metals concentration in surface water of Tasik Chini were low and within the range of natural background except for Fe and Al. In general, metal concentrations in Tasik Chini water varied temporally and spatially. The main factors influencing these metal concentrations in the water were the raining season and mining activities. Stations located at Tanjung Jerangking and Melai areas were the most effected due to those factors.

Impacts of quicklime (CaO) on the toxicity of copper (CuSO4, 5H2O) to fish and fish food organisms

Static bioassays of 96 h duration were conducted in the laboratory using fry of common carp (Cyprinus carpio), adult tubificid worm (Branchiura sowerbyi) and adult copepod plankton (Cyclops viridis) to determine LC50 values of Cu and CaO to these organisms and effects of interaction between Cu and CaO. Ninety-six hour LC(50) values of Cu to fry of common carp, worm and copepod were found to be 1.40 mgl(-1), 0.08 mgl(-1) and 0.03 mgl(-1) respectively. CaO up to 500 mgl(-1) did not produce any mortality of the fry of common carp up to 96 h. But 96 h LC50 values of CaO to worm and copepod were 83.00 mgl(-1) and 27.80 mgl(-1) respectively. When common carp fry, worm and the copepod were exposed to respective LC50 dose of Cu in presence of varying concentration of CaO, mortality of the organisms significantly reduced and was found inversely correlated with the doses of CaO [y = 48.36-0.807x, r = -0.99 (n = 7) for fish; y = 44.46-0.146x, r = -0.97 (n = 7) for worm; y = 49.46-0.66x, r = -0.99 (n = 7) for the copepod]. The present results indicate that CaO is non-toxic to fish and is capable of reducing the toxicity of Cu to fish while CaO and Cu are antagonistic to each other for the worm and the copepod. Potential of using CaO as antitoxic agent for Cu in water is discussed.

The effect of copper on osmoregulation in the freshwater amphipod Gammarus pulex

The influence of copper on osmoregulation in the freshwater amphipod Gammarus pulex was determined from the analysis of water permeability, haemolymph sodium concentration, sodium influx and gill Na(+)/K(+) ATPase and Mg(2+) ATPase activity. Exposure to nominal copper concentrations of 100 microg l(-1) or greater caused a significant reduction in both haemolymph sodium concentration and sodium influx within 4 h. Measurements of water permeability, expressed as the half-time of exchange of body water (t(1/2)), excluded structural gill damage as the cause of this fall in haemolymph sodium. Copper at 10 microg l(-1) or above in the assay solution significantly reduced gill Na(+)/K(+) ATPase activity. In contrast gill Mg(2+) ATPase activity was markedly less affected by copper. These differences in enzyme sensitivity were considered with respect to the potential mechanisms of copper toxicity.

Environmental risk limits for two phthalates, with special emphasis on endocrine disruptive properties

Environmental risk limits (ERLs) are derived for di-n-butyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP). The ERLs are derived using data on (eco)toxicology and environmental chemistry. Endpoints used are survival, growth, and reproduction. The resulting ERLs in water are 10 and 0.19 microg/L for DBP and DEHP, respectively; in fresh soil and sediment with 10% organic matter the derived ERLs are respectively 0.7 and 1 mg/kg fresh wt. In The Netherlands, measured concentrations of DBP are seldom above the ERLs, while reported concentrations for DEHP are 3 to 20 times higher than the ERL. As phthalates as a group are commonly mentioned as chemicals with possible endocrine disruptive effects, in vivo and in vitro tests for a series of phthalates with endpoints related to endocrine disruption are reviewed. In vitro and in vivo tests give a similar distinction between phthalates that can or cannot act as endocrine disrupters. The significance of these tests for the derivation of ERLs is discussed. It is concluded that the ERLs derived will give sufficient protection against endocrine disruptive effects. There is no need to include additional data for DBP and DEHP, related to endpoints other than survival, growth, or reproduction, in the derivation of ERLs.

Development of methods for evaluating toxicity to freshwater ecosystems

This article presents a summary of a collaborative research program involving five European research groups, that was partly funded by the European Commission under its Environmental Research Program. The objective of the program was to develop aquatic toxicity tests that could be used to obtain data for inclusion at Level 2 of the Risk Evaluation Scheme for the Notification of Substances as required by the 7th Amendment to EC Directive 79/831/EEC. Currently only a very limited number of test methods have been described that can be used for this purpose and these are based on an even smaller number of test species. Tests based upon algae (Chlamydomonas reinhardi, Scenedesmus subspicatus, and Euglena gracilis), protozoa (Tetrahymena pyriformis), rotifera (Brachionus calyciflorus), crustacea (Gammarus pulex), and diptera (Chironomus riparius) were developed. The tests encompassed a range of end points and were evaluated against four reference chemicals: lindane, 3, 4-dichloroaniline (DCA), atrazine, and copper. The capacity of the tests to identify concentrations that are chronically toxic in the field was addressed by comparing the effects threshold concentrations determined in the laboratory tests with those determined for similar and/or related species and end points in stream and pond mesocosm studies. The lowest no-observed-effect concentrations (NOEC), EC(x), or LC(x) values obtained for lindane, atrazine, and copper were comparable with the lowest values obtained in the mesocosms. The lowest chronic NOEC determined for DCA using the laboratory tests was approximately 200 times higher than the lowest NOEC in the mesocosms.

The impact of airport de-icing on a river: the case of the Ouseburn, Newcastle upon Tyne

The damaging effects of airport de-icers to adjacent waterways have been suggested by a number of studies, but none have been able to demonstrate these effects in a field situation. The Ouseburn is a part-urban and partrural catchment of varied land-use and includes a tributary which drains the Newcastle International Airport. The tributary contributes only 3-5% of the river's average flow, yet it had a disproportionately adverse impact upon the river. This paper demonstrates how this was linked to the airport's winter application of urea salt de-icers. An integrated approach involving hydrological, chemical, bacteriological and macroinvertebrate sampling was used. During cold weather, higher levels of ammonia were recorded in the tributary and downstream, and concentrations peaked during runoff events. It is suggested that hydrolysis, facilitated by urea digesting bacteria, and surface runoff is the mechanism by which ammonia enters the stream. The airport tributary had a less diverse macroinvertebrate fauna than expected and had larger numbers of bacteria which were able to utilise urea. In-situ bioassay experiments found large deaths of Gammarus pulex (L.) and low biotic indices at a site downstream of the airport tributary confluence. Together with elevated ammonia levels this suggested that urea application adversely impacted on the main stream's water quality and ecology. The airport authorities have responded by changing to a less toxic de-icer.