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Effects of a herbicide–insecticide mixture in freshwater microcosms: Risk assessment and ecological effect chain
Abstract
Effects of chronic application of a mixture of the herbicide atrazine and the insecticide lindane were studied in indoor freshwater plankton-dominated microcosms. The macroinvertebrate community was seriously affected at all but the lowest treatment levels, the zooplankton community at the three highest treatment levels, with crustaceans, caddisflies and dipterans being the most sensitive groups. Increased abundance of the phytoplankton taxa Cyclotella sp. was found at the highest treatment level. Threshold levels for lindane, both at population and community level, corresponded well with those reported in the literature. Atrazine produced fewer effects than expected, probably due to decreased grazer stress on the algae as a result of the lindane application. The safety factors set by the Uniform Principles for individual compounds were also found to ensure protection against chronic exposure to a mixture of a herbicide and insecticide at community level, though not always at the population level.
... Hence, they may very likely be found together in surface waters. Due to their sorption to organic material and sediment caused by high log K ow of typically 6–7 (Tomlin, 2002), the bioavailability of pyrethroids in natural environments is considerably lower than in laboratory tests conducted in glass containers in the absence of sediments and dissolved organic matter. That is, if bioavailability is considered to be equal to the amount of pesticide dissolved in the water. ...
... The microcosms were treated with concentrations of esfenvalerate corresponding to 5%, 10%, and 25% of a full field application sprayed on a 30 cm water column (0.167, 0.333, or 0.833 g L −1 ) either alone or in combination with 90 g L −1 of prochloraz (for full detail see Bjergager et al. (2011) ). The esfenvalerate concentrations correspond to approximately 1, 2 and 5 times the laboratory EC 50 for daphnids (Tomlin, 2002). The concentration of prochloraz was chosen to be within the range of concentrations observed in the field (Deb et al., 2010). ...
... Fit parameters based on nominal pesticide concentrations are given inTable 1. the synergistic interactions between prochloraz and esfenvalerate in the microcosms and at environmentally realistic concentrations implies that the synergistic interactions may also take place in natural ponds and ditches being exposed to other combinations of azoles and pyrethroids (Elsaesser and Schulz, 2008; Deb et al., 2010; Baris et al., 2010; Liess et al., 1999). The EC 50 for esfenvalerate alone in the microcosms was, as expected, 4–10 fold higher in the microcosms compared to laboratory assays (Tables 1 and 2), when based on nominal values, but was still within a factor 3 of reported laboratory EC 50 of 0.24 g L −1 (Tomlin, 2002 ). Higher EC-values in outdoor field enclosure studies compared to laboratory single species tests is a general feature across arthropod species (Roessink et al., 2005; Fairchild et al., 1992). ...
... Recent studies on the combined action of various pairs of agricultural stressors have provided further understanding of multiple stressors in aquatic ecosystems. Stressors investigated include increased bed sediment cover and nutrient concentration (e.g., Townsend et al. 2008;Riddle et al. 2009;Wagenhoff et al. 2011), nutrient and pesticide inputs (Guasch et al. 2007;Pesce et al. 2008;Dantin et al. 2010), mixtures of pesticides (atrazine and lindane, Van den Brink et al. 2009; mixture of five insecticides and five herbicides, Relyea 2009; diuron and tebuconazole, Tlili et al. 2011), and sediment and fungicide exposure (propiconazole, Wu et al. 2005;triphenyltin acetate, de Haas et al. 2005). These studies have also highlighted how responses to stressors are not always consistently negative or positive but may show a subsidy-stress relationship. ...
... These studies suggest that a strictly negative effect may not be the rule because of the complex nature of stressors in combination. Moreover, responses to mixtures of pesticides varied widely depending on the combinations of pesticides, concentrations used, duration of exposure and the organisms or taxonomic groups being tested (Relyea 2009;Van den Brink et al. 2009;Tlili et al. 2011). ...
... These types of unanticipated results can only be identified when multiple species and multiple stressors are tested and cannot be detected in a lab-test with single species. Van den Brink et al. (2009) showed that lindane exposure caused a decrease in sensitive detritivorous macroarthropods and herbivore arthropods. This allowed insensitive food competitors like worms, rotifers and snails to increase in abundance. ...
Since the soil quality Tool for Risk Identification, Assessment and Display approach introduced the “three lines of evidence” accounting for chemical, toxicological and ecological stressors to explain adverse effects in biota, the assessment of contaminant risks in the environment has significantly evolved. The concept of chemical speciation, related to water characteristics, boosted the understanding of the role of free-ion activities in the overall accumulation of pollutants in biota. New modeling concepts (e.g. biotic ligand models) and measuring techniques were developed. This in turn triggered widespread research addressing the quantitative role of sediment in the overall water quality, focusing on redox interfaces. For contaminant mixtures in river catchments, complex relations between (bio)availability of compounds, including nutrients, help to explain aquatic toxicity. Variation in ecological patterns and processes across environmental or spatiotemporal gradients occur, which may identify ecological factors that influence contaminant fate and effects. Empirical evidence by meta-analysis and theoretical underpinning by modelling showed relationships between population growth rates and carrying capacities, across chemicals and across species. The potentially affected fraction (PAF) of species may be related to the mean species abundance, an often-used indicator in global change studies. Knowledge gaps remain on how pollutants travel through ecological communities and which species and species-relationships are affected. Outdoor experimental systems that examine the natural environment under controlled conditions may be useful at the higher biological level to investigate the impact of stressors on a variety of species, including mutual interactions.
... When these substances enter water bodies, they interact with the abiotic and biotic components of the ecosystem. The interaction with biota involves processes of entry, metabolization, and/or accumulation in organisms, which can produce direct or indirect deleterious effects [30][31][32]. In events of severe contamination, it is expected that species or entire groups of organisms that are more sensitive or lack escape mechanisms will disappear [33,34]. ...
Neotropical ecosystems are highly biodiverse; however, the excessive use of pesticides has polluted freshwaters, with deleterious effects on aquatic biota. This study aims to analyze concentrations of active ingredients (a.i) of pesticides and the risks posed to freshwater Neotropical ecosystems. We compiled information from 1036 superficial water samples taken in Costa Rica between 2009 and 2019. We calculated the detection frequency for 85 a.i. and compared the concentrations with international regulations. The most frequently detected pesticides were diuron, ametryn, pyrimethanil, flutolanil, diazinon, azoxystrobin, buprofezin, and epoxiconazole, with presence in >20% of the samples. We observed 32 pesticides with concentrations that exceeded international regulations, and the ecological risk to aquatic biota (assessed using the multi-substance potentially affected fraction model (msPAF)) revealed that 5% and 13% of the samples from Costa Rica pose a high or moderate acute risk, especially to primary producers and arthropods. Other Neotropical countries are experiencing the same trend with high loads of pesticides and consequent high risk to aquatic ecosystems. This information is highly valuable for authorities dealing with prospective and retrospective risk assessments for regulatory decisions in tropical countries. At the same time, this study highlights the need for systematic pesticide residue monitoring of fresh waters in the Neotropical region.
... Further, the release of dissolved substances from the death of zooplankton could result in increased CON level (Table S4). The effects of pesticides on DO-pH-CON-alkalinity patterns via direct or indirect impacts on photosynthesis have been observed frequently (Van Wijngaarden et al., 2005;Daam et al., 2009;Van den Brink et al., 2009;Lin et al., 2012). Further, some studies have reported high ammonia excretion by daphnids (MacKay and Elser, 1998;Wojtal-Frankiewicz and Frankiewicz, 2011). ...
To evaluate the aquatic hazards of the insect juvenile hormone analogue fenoxycarb, a single application (0, 48.8, 156.3, 500, 1600, and 5120 μg/L) of it was done in indoor freshwater systems dominated by Daphnia carinata (daphnid) and Dolerocypris sinensis (ostracoda). The responses of zooplankton (counted by abundance and the activity and immuno-reactive content of free N-Acetyl-β-D-glucosaminidase (NAGase)), phytoplankton (counted by chlorophyll and phycocyanin), planktonic bacteria and fungi, and some water quality parameters were investigated in a period of 35 d. Results of the study showed that the ostracoda was more sensitive than daphnid, with time-weighted average (TWA)-based no observed effect concentrations (NOECs) to be 8.45 and 12.66 μg/L in systems without humic acid addition (HA−) and to be 6.37 and 9.54 μg/L in systems with humic acid addition (HA+). The duration of treatment-related effects in the ostracoda population was longer than the daphnid population (21 vs. 14 days). Besides, the data analysis indicated that the toxicity of fenoxycarb was significantly enhanced in the HA+ systems. Owing to the reduced grazing pressure, the concentrations of chlorophyll and phycocyanin increased in the two highest treatments. The increase in photosynthesis along with a reduced animal excretion led to an increase in pH and a decrease in nutrient contents. These changes seemed to have an effect on the microbial communities. For example, the abundances of some opportunistic pathogens of aquatic animals (e.g. Aeromonas and Cladosporium) and organic-pollutant-degrading microorganisms (e.g. Ancylobacter and Azospirillum) increased significantly in microbial communities, but the abundances of Pedobacter, Candidatus Planktoluna, and Rhodobacter (photosynthetic bacteria) markedly decreased. This study provides useful information to understand the ecotoxicological impacts of fenoxycarb at the population and community levels while integrating the effects of HA on toxicity.
... Ostracoda and rotifera are considered to be important taxa in a microcosm for precise community evaluation; however, lack of or poor abundance of ostracoda taxa 29,[37][38][39][40][41][42] has often been observed in comparison with other taxa (cladocera 43,44) or ro- tifera 45) ) in indoor microcosms using natural zooplankton. In fact, rotifera frequently play a unique role in ecological adapta- tion via indirect population increase, as shown in Fig. 6. ...
Effects of esfenvalerate on zooplankton and their recovery potential were studied using an indoor synthetic model ecosystem. Esfenvalerate was applied to the system by direct spiking to overlying water or the introduction of treated slurry soil to imitate drift and run-off exposure. Four zooplankton taxa, Daphnia magna (Cladocera), Heterocypris incongruens (Ostracoda), Cyclops sp. (Copepoda), and Brachionus calyciflorus (Rotifera), were exposed to esfenvalerate with Raphidocelis subcapitata (green alga). In a drift scenario, lower doses (0.02–0.5 µg/L) showed slight or negligible effects, but the results for the highest dose (5 µg/L) indicated direct effects, as remarkable population decreases were observed for three taxa (except rotifera). However, for the latter dose, results of weekly or single (Day-15) zooplankton re-introductions after dosing demonstrated resilient recovery. In a run-off scenario, a nominal dose of 20 µg/L, in which the measured water concentrations remained at 3–6%, had effects similar to those of the high drift exposure scenario for cladocera and ostracoda.
... benthic invertebrate grazers (Ward et al. 1995, Van den Brink et al. 2009). However, we do not find it entirely surprising, as periphyton communities in our microcosms seemed to be nutrient and light limited. ...
Chlorpyrifos is one of the most widely used agricultural insecticides in the world, but to date there is limited empirical information about its potential to interact with other common agricultural stressors. We conducted a 15-day, community-level microcosm experiment evaluating individual and combined effects of chlorpyrifos, nutrient enrichment, and sedimentation on stream invertebrate communities (abundance, biomass, richness, size structure, composition) and ecosystem processes (primary productivity and leaf decomposition). We found that sedimentation was the most detrimental stressor, with significant negative impacts on most invertebrate community and ecosystem function variables. Even though chlorpyrifos did not cause significant invertebrate mortality in the microcosms, it still altered ecosystem function by lowering leaf decomposition rates, probably through sublethal inhibition of invertebrate shredders. Furthermore, we observed a significant reversal interaction between chlorpyrifos and sediment for small-sized invertebrates collected in gravel (abundance in sediment x insecticide microcosms was 2.4 times lower than predicted by additivity), as well as an antagonistic interaction with nutrients on invertebrate richness in the same microhabitat (richness in nutrient x insecticide microcosms was 1.6 times higher than predicted by additivity). Our results suggest that chlorpyrifos has the potential to alter freshwater ecosystem function and interact non-additively with other common agricultural stressors. These findings are in keeping with a growing body of research highlighting that multiple stressor interactions and ecosystem processes should be considered when evaluating the impacts of organic toxicants on freshwater ecosystems. This article is protected by copyright. All rights reserved.
... Relatively little information is available about the effects of realistic combinations of pesticides on the structure and functioning of ecosystems, such as those presented in Van Wijngaarden et al. (2004) and Van Den Brink et al. (2009). To partly overcome this problem, further research to investigate effects on communities at field and semi-field level, both for aquatic (e.g. ...
Organisms are frequently exposed to mixtures of chemical contaminants in the environment, causing a potential “cocktail effect”, or combined effect. The joint action of different molecules with similar or different modes of action could result in a potentially unlimited number of additives, synergistic or antagonistic combinations. Since the large number of contaminants makes it impossible to perform ecotoxicity tests for each potential mixture, a robust approach for prospective environmental risk assessment of chemical mixtures is needed.
A number of recent publications by the European Commission and the authorities in charge prove the increasing interest that is spreading in the European community towards the topic of the assessment of chemical mixtures.
The current EU regulation for Plant Protection Products authorization (Reg. 1107/2009 EC) explicitly requires the evaluation of the potential combined effects of active substances.
We reviewed current methods and limitations of mixture assessment of pesticides (7 fungicides and 4 herbicides) through the analysis of the approaches adopted to investigate possible risks for different non-target organisms.
The Concentration Addition (CA) approach was the most used approach to predict multiple toxicity to non-target organisms. The guidance for birds and mammals first introduced standard procedures to assess the multiple toxicity based on on CA concept. The recent aquatic EFSA guidance introduced some requirements to evaluate potential mixture toxicity, while the current guidance requirements for terrestrial organisms still lack clear indications on how to conduct the assessment. Moreover, new indications come from the draft guidance for the assessment of terrestrial plants and in-soil organisms. However, the approval and implementation of these new guidelines are still at a developmental stage.
Some final considerations are drawn on the future possibilities to improve risk assessment procedures so as to identify harmful effects of pesticides mixtures on non-target organisms.
... The impact of pesticide contamination in aquatic ecosystem is tremendous. Microcosms have been widely used as a research method for the environmental fate of pesticides and have a series of advantages such as authenticity, flexibility, a high performance-price ratio and security (Colombo et al., 2013;Laabs et al., 2007;Van den Brink et al., 2009). In an artificial microcosm, the incubation conditions can be controlled and the fate of the target compound can be clearly understood. ...
... This was analysed for risk relationships, the most frequent of which (n = 5) were 'potential agricultural chemical pesticide risk to surface water macroinvertebrates' and 'potential agricultural chemical pesticide risk to surface water quality'. With dominant parameters described for the source categories (agricultural and chemical, respectively), but less so for the receptor category (macroinvertebrates and water quality, respectively), several receptor parameters were combined (multiple organisms, algae, crustaceans, and macroinvertebrates), establishing a defined risk relationship (n = 13; Cuppen et al., 2000;Mastin and Rodgers, 2000;Palma et al., 2004;van Wijngaarden et al., 2004;Wan et al., 2006;Schuler and Rand, 2008;Siemering et al., 2008;van den Brink et al., 2009;Vryzas et al., 2009;Burgert et al., 2011;Damásio et al., 2011;Guy et al., 2011;Vryzas et al., 2011) of 'potential agricultural chemical pesticide risk to surface water organisms', which was as specific as defensible and selected as the risk relationship for the case study. This allowed the detailed examinations of uncertainties for this case study ERA. ...
A reliable characterisation of uncertainties can aid uncertainty identification during environmental risk assessments (ERAs). However, typologies can be implemented inconsistently, causing uncertainties to go unidentified. We present an approach based on nine structured elicitations, in which subject-matter experts, for pesticide risks to surface water organisms, validate and assess three dimensions of uncertainty: its level (the severity of uncertainty, ranging from determinism to ignorance); nature (whether the uncertainty is epistemic or aleatory); and location (the data source or area in which the uncertainty arises). Risk characterisation contains the highest median levels of uncertainty, associated with estimating, aggregating and evaluating the magnitude of risks. Regarding the locations in which uncertainty is manifest, data uncertainty is dominant in problem formulation, exposure assessment and effects assessment. The comprehensive description of uncertainty described will enable risk analysts to prioritise the required phases, groups of tasks, or individual tasks within a risk analysis according to the highest levels of uncertainty, the potential for uncertainty to be reduced or quantified, or the types of location-based uncertainty, thus aiding uncertainty prioritisation during environmental risk assessments. In turn, it is expected to inform investment in uncertainty reduction or targeted risk management action.
... Changes in biomass and physicochemical characteristics of aquatic ecosystems in turn generate subordinate concentration variation of nutrients (Koelmans et al., 2001). Accurate analysis and prediction of the concentration of plankton and nutrient plays a key role in ecological risk assessment, environmental impact assessment, and wastewater treatment engineering (Jak et al., 1996;Van den Brink et al., 2009;Wang and Chen, 2016;Wang et al., 2013;Wang and Chen, 2015;Zeng et al., 2014;Wu and Chen, 2014). ...
Closely related to the solar photocycle, plankton growth in eutrophic waters displays a diurnal variation because of photosynthesis and respiration. Presented in this paper is an analytical study of the diurnal variation of mean concentration of plankton and nutrient in an open channel eutrophic flow initiated by an instantaneous emission. The evolution of the concentration is shown driven by the combination of hydraulic dispersion and diurnal reaction between plankton and nutrient. The analytical solution for longitudinal distribution of concentration is rigorously derived and illustrated, based on the time dependent hydraulic dispersivity. Numerical results are presented and characterized by the reaction rate, yield factor and period for the diurnal reaction and the P clet number of the flow. For typical applications such as ecological risk assessment and environmental impact assessment, the upper and lower limits of critical length and duration of five typical pollutant concentrations are concretely illustrated for given concentration criterions. Remarkable diurnal variations are revealed up to around one third in the critical length and duration for plankton, and about ten percent for nutrient.
... Today, it is known that single pesticides cause adverse effects on non-target aquatic organisms and also pesticide mixtures synergistically increase toxicity in these organisms. However, data on the effects of pesticide mixtures on aquatic organisms are scarce (Hayes et al., 2006; Van den Brink et al., 2009 ). Amphibians live in more complex natural environments that contain a great number of pesticide mixtures (Wharfe, 2004; Abrantes et al., 2010). ...
In this study, we evaluated the toxic effects of a glyphosate-based herbicide (GBH) and a methidathionbased insecticide (MBI), individually and in combination, on premetamorphic tadpoles of three anuran species: Pelophylax ridibundus, Xenopus laevis, and Bufotes viridis. Based on the determined 96-h LC50 values of each species, the effects of a series of sublethal concentrations of single pesticides and their mixtures after 96-h exposure and also the time-related effects of a high sublethal concentration of each pesticide were evaluated, with determination of changes in selected biomarkers: glutathione S-transferase (GST), glutathione reductase (GR), acetylcholinesterase (AChE), carboxylesterase (CaE), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH). Also, the integrated biomarker response (IBR) was used to assess biomarker responses and quantitatively evaluate toxicological effects. Isozyme differences in CaE inhibition were assessed using native page electrophoresis; results showed that GBH to cause structural changes in the enzyme but not CaE inhibition in P. ridibundus. In general, single MBI and pesticide mixture exposures increased GST activity, while single GBH exposures decreased GST activity in
exposed tadpoles. The AChE and CaE activities were inhibited after exposure to all single MBI and
pesticide mixtures. Also, higher IBR values and GST, GR, AST, and LDH activities were determined for pesticide mixtures compared with single-pesticide exposure. This situation may be indicative of a synergistic interaction between pesticides and a sign of a more stressful condition.
... Ainsi, en eau douce, la toxicité du chlorpyriphos vis-à-vis du zooplancton s'accompagne d'une augmentation du phytoplancton (Hurlbert et al., 1972 ;Papst et Boyer, 1980 ;Brock et al., 1992 ;Fleeger et al., 2003 ;Van Wijngaarden et al., 2005). Cet effet est retrouvé lorsque deux insecticides (chlorpyriphos + lindane) ou un herbicide (atrazine) + un insecticide (lindane) ou un seul insecticide (cyperméthrine) sont ajoutés au microcosme (Van den Brink et al., 2002 ;Friberg-Jensen et al., 2003 ;Van den Brink et al., 2009). Peu de données existent concernant le milieu marin ; cependant en eau moyennement salée, la suppression par le chlorpyriphos du zooplancton coïncide avec un bloom d'Anabaena flos-aquae (Simon et al., 1995). ...
This work aims to study the effects of a few pesticides and one adjuvant on marine organisms, representatives of four trophic levels : micro-algae, echinoderm, bivalves and fish. Analysis of the pollu-sensitivity was based on the utilisation of existing bio-assays or adapted to this study.Phytotoxic assessments were conducted on three phytoplanktonic species (Chaetoceros calcitrans, Isochrysis aff. Galbana et Tetraselmis suecica) using the fungicide epoxiconazole and the adjuvant nonylphenol. Sensitivity to these toxicants of C. calcitrans and I. aff. Galbana was high. Thus, when C. calcitrans was grown in a medium simulating pre-winter conditions in Gabès Gulf, EC50 values were respectively, 2.31 mg/L and 2.9 μg/L for epoxiconazole active ingredient and epoxiconazole-formulated. These results questioned the use of ecotoxicological data obtained solely using active molecules of pesticides rather the complete formulation and show that non-target micro-algae may be affected by a triazole fungicide.Moreover, cell age, light and nutrient composition induced changes in epoxiconazole sensitivity, suggesting that cellular density is an important parameter in toxicity tests.Analysis of a few physiological parameters show that contaminants used in this study induce an increase of pigment content, ATP synthesis, and rates of oxygen exchanges while the cell volume enlarges. Consequently, the toxicants might reduce the growth rate, by a prolongation of the cell cycle without affecting the production of new material for the construction of new cells.Bioassays were conducted using microcosms during a bloom of the toxic algae Karenia selliformis in the Gulf of Gabès. The different toxicants (epoxiconazole, chlorpyrifos-éthyl, nonyphenol) produced drastic changes in the phytoplankton communities, depending on the type and concentration of the contaminant.Phytotoxic assessments were conducted on marine animal models, using different developmental stages: embryo-larval development (sea urchin, oyster, and clam), metamorphosis larvae (clam) and larvae survival (turbot). Results show that turbot larvae are most sensitive to the action of contaminants with EC50 values ranging from 2.78 to 492 μg/L depending on the toxic and that the metamorphosis is the stage the most sensitive of the three stages of development of clam studied.The pollutants produced developmental and embryonic abnormalities that might induce a reduction in the natural production by acting i) directly on the development of the marine organisms and ii) indirectly on the quality and bioavailability of food through the variation of phytoplankton biomass.These results underline the need to study pollutant effects on marine organisms having different organizations to evaluate their full impact.
... Also, although it is possible to assess the effects of simple mixtures with this kind of approach by testing compounds individually, together with binary or ternary combinations (Pesce et al. 2010b), it is practically impossible to consider all the combinations that can occur in complex mixtures such as those found in the environment. More generally, data on the impact of such mixtures is scant, especially when considering communitylevel effects (Van den Brink et al. 2009; Pesce et al. 2011b), and debate continues on the best way to deal with this issue (Knauert et al. 2009). To address the problem of realistic mixtures, it has been suggested that passive sampling be combined with the assessment of extract toxicity via bioassays (Escher et al. 2006; Bopp et al. 2007). ...
Streams located in vineyard areas are particularly exposed to mixtures of dissolved and particulate contaminants such as metals and organic pesticides. In this context, phototrophic biofilms are increasingly used as indicators of river water contaminations through PICT (pollution-induced community tolerance) assessments based on short-term toxicity tests with individual or mixtures of toxicants. We conducted a laboratory experiment to evaluate the relative influence of the dissolved and particulate fractions on the effects of metals and pesticides on phototrophic biofilms in a context of contamination from a vineyard watershed. Three sets of artificial channels were supplied with (i) unfiltered water from a stream reference site, (ii) unfiltered water from a stream contaminated site, and (iii) filtered water (0.45 µm) from the same contaminated site. Biofilm growth, diatom community structure and dissolved toxicant concentrations differed slightly between channels supplied with unfiltered or filtered water from the contaminated site. However, PICT assessments with individual toxicants or mixtures of toxicants extracted from passive samplers suggested no significant difference in tolerance to metals and organic pesticides between phototrophic communities supplied with unfiltered or filtered contaminated water. Our results confirm the use of extracts from passive samplers as a promising approach in short-term toxicity tests to characterize impacts of contamination on aquatic communities.
... A second challenge relates to the presence of multiple stressors in real ecosystems, as opposed to the presence of single chemicals in the toxicity tests on which prospective ERAs are generally based. The performance of individuals is therefore not solely determined by the presence of individual chemicals but by multiple stressors, including (mixtures of) chemicals (Verbruggen and Van den Brink 2010), possibly targeting different trophic levels (Van den Brink et al. 2009), and other stress factors such as, for example, changes in temperature (Heugens et al. 2001). A third scientific challenge for ERA includes the incorporation of recovery-inducing processes. ...
Current techniques for the ecological risk assessment of chemical substances are often criticised for their lack of environmental realism, ecological relevance and methodological accuracy. ChimERA is a 3-year project (2013-2016), funded by Cefic's Long Range Initiative (LRI) that aims to address some of these concerns by developing and testing mechanistic fate and effect models, and coupling of these models into one integrated platform for risk assessment. This paper discusses the backdrop against which this project was initiated and lists its objectives and planned methodology.
... Even though pesticides frequently occur in mixtures (e.g. (Rabiet et al. 2010)), data on the effects of pesticide mixtures is scarce, especially when considering community-level effects (Van den Brink et al. 2009; Pesce et al. 2012). However, there is still debate over the best way to address this issue (Knauert et al. 2008; Knauert et al. 2009), and it can be argued that the assessment of mixture effects is in its infancy (Belden et al. 2007). ...
Global climate change will affect worldwide agriculture in many ways. The anticipated or already occurring changes raise concerns about the sustainability of production and the ability of agriculture to feed human populations. This appeals to sustainable agriculture providing ecosystem services more efficiently than today, and accordingly to substantial evolutions of pesticide risk assessment (RA) and risk management (RM). The RA/RM issues were discussed by two European research networks in a 2011 workshop. The RA-RM-monitoring conceptual cycle tends to be virtual, with poor connections between certain steps. The design of more comprehensive emissions scenarios could improve the accuracy of predicted runoff transport, while the microcosm/mesocosm approach could help establish causal relationships between fate / exposure and populations / communities. Combined with ecological modelling, effects can be extrapolated to higher spatial and temporal scales. Risk management of diffuse sources should be designed simultaneously at the watershed and individual plot scales. Monitoring is key to assessing the effectiveness of risk reduction measures reduce and evaluate the overall quality of the aquatic compartment. More flexible monitoring strategies clearly linked to RM decisions are therefore needed. Although some technical questions remain, it is time to apply passive samplers more routinely. A set of research and development needs covering the whole RA/RM cycle is listed in conclusion.
... Nevertheless, from micro/mesocosm experiments that addressed exposure to realistic packages of pesticides used in potato and flower bulb crops (with weekly application of either an insecticide, herbicide, fungicide or a combination) it appeared that the largest proportion of the risk was caused by one or a few active ingredients only [4, 5]. In addition, from microcosm experiments that simulated chronic exposure to two or three pesticides with a similar or dissimilar toxic mode-of-action, it appeared that the threshold level for toxic effects usually is ≥ 0.01 TU (on basis of standard acute toxicity data) and that synergistic toxic effects are rarely observed [6, 7, 8]. The lessons learned from experimental studies with pesticides indicate that it is worthwhile to make a distinction in two types of cumulative stress, viz., (i) repeated pulse exposures that may differ in toxic modeof-action and that may be toxicologically dependent [9], and (ii) mixture toxicity of pollutants that may differ in toxic mode-of-action [8, 10]. ...
It is now more than ten years ago that the Water Framework Directive (WFD) was adopted by the European Parliament. The main objectives of the WFD are (i) to achieve good ecological and chemical status for inland surface waters, transitional waters and coastal waters in EU Member States, (ii) to assess the ecological and chemical status of these water bodies by means of monitoring programmes, and (iii) to implement programmes of measures to reduce environmental stress to an acceptable level. By adopting the WFD a fundamental change in management objective was introduced in the European Union, from merely pollution control to ensuring ecosystem integrity as a whole [1]. The ecological status of WFD water bodies is assessed by monitoring of biological quality elements (e.g. fish, macroinvertebrates, macrophytes, benthic diatoms, phytoplankton), general chemical and physico-chemical quality elements (e.g. pH, alkalinity, nutrients) and hydromorphological quality elements. These quality elements monitored in water bodies are compared with the status of more or less pristine reference ecosystems. If in WFD water bodies the ecological status deviates too much from the reference condition action is needed for achieving the acceptable ecological status. The chemical status of water bodies is assessed by comparing chemical monitoring data with Environmental Quality Standards (EQS) for priority (hazardous) substances and other relevant substances. Currently, 41 priority (hazardous) substances are listed in the European Union, but a regular update of this list with emerging substances is anticipated. If in water bodies exposure concentrations of one or more of these priority (hazardous) substances are not in compliance with the officially published EQS’s for these pollutants a good chemical status is not reached and action is needed to improve this. In contrast to the EU-level priority (hazardous) substances the other relevant substances are river basin or Member State specific. These other relevant substances have been selected because they are believed to potentially impair the ecological status of specific WFD water bodies and/or related human health aspects. The methodology to derive the EQS’s for other relevant substances is similar to that of the priority (hazardous) substances. This methodology is described in the new Technical Guidance Document for deriving Environmental Quality Standards (will be officially released in 2011). In European river basins the priority (hazardous) substances and river specific pollutants have to be measured on a regular basis. Under the umbrella of the WFD, EQS derivation is primarily based on a single substance toxicity assessment approach. In exceptional cases EQS’s for mixtures may be derived when their qualitative and quantitative composition is well-defined and/or well described (e.g. biocide preparations, PCB’s, dioxins). The concentration addition (CA) concept is used as a default when setting EQS’s for mixtures. Although compliance with good chemical status is primarily based on EQS’s for individual substances, cumulative stress (including mixtures) of toxicants may be identified as a main pressure affecting ecological status. In that case the cumulative risks caused by pollutants have to be reduced.
... Various pairs of stressors have been investigated, including increased bed sediment cover and nutrient concentration (e.g. Wagenhoff et al., 2011), nutrient and pesticide inputs (Pesce et al., 2008), mixtures of pesticides (atrazine and lindane, Van den Brink et al., 2009) and sediment and fungicide exposure (triphenyltin acetate, de Haas et al., 2005). These studies have highlighted how full assessment of risk from a single stressor may be complicated by enhancement or suppression of its effect by another co-occurring stressor. ...
Previous research on the combined action of various paired agricultural stressors in stream ecosystems has shown that non‐additive outcomes (i.e. synergisms or antagonisms) are more common than simple additive effects on communities, but the interplay between deposited fine sediment and widely used herbicides such as glyphosate as stressors is not well understood.
A 28‐day experiment in outdoor stream mesocosms simulated effects of varying levels of fine sediment and a glyphosate‐based herbicide on macroinvertebrates and ecosystem function (leaf breakdown) in a fully factorial repeated‐measures design. Our aim was to determine whether (i) increased levels of sediment and glyphosate had individual and/or additive combined effects on invertebrates and leaf breakdown, (ii) increased sediment reduced the toxicity of glyphosate (antagonistic multiple stressor interaction) or (iii) sediment‐adsorbed glyphosate prolonged the effects of exposure (synergistic interaction).
Sediment addition positively or negatively affected eight of the 10 most common invertebrate taxa colonising the mesocosms and increased or decreased the representation of 12 of 15 biological trait categories possessed by the invertebrates, while glyphosate addition negatively affected only two taxa and two invertebrate trait categories, indicating that glyphosate entering streams as a result of herbicide addition to farmland is less likely to be problematic for invertebrates than fine sediment from catchment erosion.
No significant overall sediment‐by‐glyphosate interaction was detected for invertebrate taxonomic or trait compositions or for any common individual taxon, trait or community metric, indicating that the two stressors were acting additively (i.e. without interaction), rather than synergistically or antagonistically.
Leaf breakdown rates (measured as mass and strength loss) were accelerated by sediment and glyphosate as individual stressors. Further, the two stressors interacted for leaf strength loss, with their combined effect being less than additive when both stressors were at their highest levels.
Population, community and ecosystem variables responded differently to multiple stressors, highlighting the value of combining structural, functional taxonomic and trait data to assess the effects of anthropogenic stressors.
... The science on the toxicity of chemical mixtures focuses primarily on how effects of mixtures should be assessed at the individual level (Backhaus and Faust 2012). Efforts to understand how chemical cocktails affect ecosystems are scarce (Van den Brink et al. 2009). The few studies available show that an alternative appreciation of mixture toxicity and its concepts of synergism and antagonism is needed that moves beyond the individual level. ...
One of the objectives of the European Union's (EU) ecological risk assessment of chemicals (ERA) is to derive maximum environmental concentrations that are not expected to cause adverse ecological effects. To this end, related EU directives list protection goals as well as guidelines that should be used to reach these goals. It is generally accepted that the individual-level endpoints on which these guidelines are based do not correspond to the listed population- and ecosystem-level protection goals. In this paper, we identify 5 research topics that are key to bridge this gap: the refinement of population-level effects and recovery rates by explicitly taking into account competition (1) and predation (2); the assessment of chemical effects on biodiversity (3); the assessment of chemical stress on ecosystem functions and services (4); and the quantification of the effects of chemical mixtures (5). In addition, we illustrate why an ecosystem perspective is needed to address these topics and to inform the risk assessment process. We propose the use of existing ecotoxicological community, food web, and ecosystem models to tackle these issues and discuss why new models are needed to predict chemical effects on biodiversity. Integr Environ Assess Manag © 2013 SETAC.
... Concentrations, at which effects were observed in that study, however, were higher than that tested in our mesoscosm study. For insecticides (e.g., lindane), Van den Brink et al. (2009) found moderate effects on population level but not on community level after chronic exposure to a herbicide and insecticide mixture at HC 5 concentrations and recommended to multiply the value by 0.1 to account for the chronic nature of the exposure. ...
Traces of pesticides are frequently detected in surface waters. As a consequence, specific environmental quality criteria (EQS) for a set of single pesticides in surface waters were defined by the environmental authorities in several countries. In this context, the aim of this study was to investigate if the sum of the five percentile hazard concentration (ΣHC(5-95percent), meaning that 5 percent of the aquatic assemblage remains affected considering a 95 percent confidence interval) of three herbicides with the same mode of action derived from a species sensitivity distribution based on acute toxicity data (EC(50) values) of the most sensitive taxonomic group is a suitable EQS for surface water addressing the occurrence of herbicide mixtures as common exposure scenario. Therefore, an outdoor mesocosm study was performed with three replicates per treatment for a period of 173 days. Results demonstrated that a constant long-term exposure over 35 days to the HC(5-95 percent) of a mixture of three PSII inhibitors did not lead to adverse effects on the aquatic community in this field mesocosm study. Neither adverse effects on very sensitive functional endpoints such as photosynthesis measurements of algae and macrophytes nor adverse effects on structural endpoints such as abundance data and species composition were determined. In contrast and as a positive control, the HC(30) treatment affected statistically significant all investigated endpoints and it was demonstrated that the PSII inhibitors acted additive on various level of organization (Knauert et al., 2008). This study is filling the gap that no empirical evidence is published indicating that the chronic exposure at the HC(5-95 percent) estimate is leading to no adverse effects for the aquatic community and is therefore a suitable EQS for surface waters in the agriculture landscape.
... In this respect, managers may wish to address the question of synergistic stressor impacts: Will the increase of cyanoHABs and their impacts on communities under both temperature increase and pesticides combined be higher than the expected increases caused by temperature increase and pesticides separately? Mesocosm studies have revealed interactions of different toxic stressors at the community level [55] and may therefore be an ideal tool for addressing the above question. Ecosystem modeling may in this regard be useful to generate testable hypotheses for different pesticides and their interaction with temperature effects, together with more experimental data on the combined effects of cyanotoxins and chemical contaminants on individual zooplankton. ...
Increased temperature and other environmental effects of global climate change (GCC) have documented impacts on many species (e.g., polar bears, amphibians, coral reefs) as well as on ecosystem processes and species interactions (e.g., the timing of predator-prey interactions). A challenge for ecotoxicologists is to predict how joint effects of climatic stress and toxicants measured at the individual level (e.g., reduced survival and reproduction) will be manifested at the population level (e.g., population growth rate, extinction risk) and community level (e.g., species richness, food-web structure). The authors discuss how population- and community-level responses to toxicants under GCC are likely to be influenced by various ecological mechanisms. Stress due to GCC may reduce the potential for resistance to and recovery from toxicant exposure. Long-term toxicant exposure can result in acquired tolerance to this stressor at the population or community level, but an associated cost of tolerance may be the reduced potential for tolerance to subsequent climatic stress (or vice versa). Moreover, GCC can induce large-scale shifts in community composition, which may affect the vulnerability of communities to other stressors. Ecological modeling based on species traits (representing life-history traits, population vulnerability, sensitivity to toxicants, and sensitivity to climate change) can be a promising approach for predicting combined impacts of GCC and toxicants on populations and communities. Environ. Toxicol. Chem. © 2012 SETAC.
... Compensation of direct toxic effects on phytoplankton due to toxicant-induced reduced grazing by zooplankton has been observed in aquatic model ecosystem experiments treated with other broad spectrum fungicides (e.g. Van den Brink et al. 2000; Roessink et al. 2006) and biocides (Fliedner et al. 1997; Jak et al. 1998) and in microcosms treated with an insecticide–herbicide mixture (Van den Brink et al. 2009). The observed short-term increases in population densities of several macroinvertebrate taxa in our microcosm experiment may also be due to shifts in species interactions caused by direct toxic effects of metiram. ...
The ecological impact of the dithiocarbamate fungicide metiram was studied in outdoor freshwater microcosms, consisting of 14 enclosures placed in an experimental ditch. The microcosms were treated three times (interval 7 days) with the formulated product BAS 222 28F (Polyram®). Intended metiram concentrations in the overlying water were 0, 4, 12, 36, 108 and 324 μg a.i./L. Responses of zooplankton, macroinvertebrates, phytoplankton, macrophytes, microbes and community metabolism endpoints were investigated. Dissipation half-life (DT50) of metiram was approximately 1–6 h in the water column of the microcosm test system and the metabolites formed were not persistent. Multivariate analysis indicated treatment-related effects on the zooplankton (NOECcommunity = 36 μg a.i./L). Consistent treatment-related effects on the phytoplankton and macroinvertebrate communities and on the sediment microbial community could not be demonstrated or were minor. There was no evidence that metiram affected the biomass, abundance or functioning of aquatic hyphomycetes on decomposing alder leaves. The most sensitive populations in the microcosms comprised representatives of Rotifera with a NOEC of 12 μg a.i./L on isolated sampling days and a NOEC of 36 μg a.i./L on consecutive samplings. At the highest treatment-level populations of Copepoda (zooplankton) and the blue-green alga Anabaena (phytoplankton) also showed a short-term decline on consecutive sampling days (NOEC = 108 μg a.i./L). Indirect effects in the form of short-term increases in the abundance of a few macroinvertebrate and several phytoplankton taxa were also observed. The overall community and population level no-observed-effect concentration (NOECmicrocosm) was 12–36 μg a.i./L. At higher treatment levels, including the test systems that received the highest dose, ecological recovery of affected measurement endpoints was fast (effect period < 8 weeks).
Electronic supplementary material
The online version of this article (doi:10.1007/s10646-012-0909-0) contains supplementary material, which is available to authorized users.
Diflubenzuron (DFB) is a benzoylbenzourea insect growth regulator widely used in agriculture, horticulture, and vector control. Therefore, it can easily pollute water bodies and cause harm to aquatic life and ecosystems. To evaluate the impact of DFB on atyid shrimp Neocaridina palmate, the insecticide was applied, at 0, 0.74, 2.222, 6.667, 20, and 60 μg L-1, to indoor systems dominated by submerged plant Ceratophyllum demersum. The highest no observed effect concentration and the lowest observed effect concentration was determined to be 0.167 and 0.536 μg L-1, respectively, as it was counted with either activity or immune-reactive content of chitobiase. Subcellular indices were more sensitive, with a lowest observed effect concentration below 0.107 μg L-1. Principal response curves (PRC) and principal component analysis (PCA) showed that DFB reduced the biomass of C. demersum and the content of chlorophyll-a and phycocyanin in the media. The biomass of periphyton were promoted at the high concentrations. According to the PRC and PCA, DFB reduced the bacterial population related to photoautotrophy, sulphur reduction, and sulphur oxidation and it promoted those related to photoheterotrophy, nitrate reduction, nitrate denitrification, and nitrogen fixation. Besides, DFB reduced fungi related to denitrification. PRC and PCA showed that DFB had a negative impact on pH and dissolved oxygen levels and a positive impact on NH4-N, NO2-N, PO4-P, and conductivity, suggesting the deterioration in quality of water. This study provided useful information for understanding the ecotoxicological effects of DFB at population and community levels.
Tebufenpyrad are widely used for control leaf mites in orchard and may enter freshwater systems through runoff, spray drift, and so on. Few papers have reported the side effect of the pesticide on population dynamics of aquatic taxa such as shrimps, gastropods, macrophytes, phytoplankton, and bacteria. Here, we tested the effect of a single application of tebufenpyrad on Neocaridina palmata, Physa fontinalis, Ceratophyllum demersum, Simocephalus vetulus, Dolerocypris sinensis, and so on, by indoor systems. The TWA (Time-weighted average)-based no observed effect concentration (NOEC) and lowest observed effect concentration (LOEC) for Neocaridina palmata, which were counted by wet weight, were 0.67 and 2.33 μg/L, respectively, and the dose-related effect lasting 21 d. According to our study, chitobiase could be used to quantify the effects of the pesticide on shrimp despite the interference from P. fontinalis, which was finally corrected by employing of antibodies. The NOEC and LOEC were thus determined to be 1.41 and ≤ 5.64 μg/L, respectively, which were higher than the values that was counted by wet weight. Principal component analysis (PCA) and principal response curve (PRC) investigation showed that the pesticide suppressed population of C. demersum, and phytoplankton, while the Physa fontinalis, S. vetulus, and D. sinensis were stimulated by the pesticide. Illumina MiSeq was used to determine the alteration in bacterial community within the systems. The results of PRC and PCA analyses showed that tebufenpyrad induced flora of nitrate reducing, nitrate denitrifying, thiosulfate oxidation, ureolysis, and methanol oxidation, while it suppressed flora of cellulolysis. Tebufenpyrad was found to have a negative effect on water quality indicators such as pH, DO, NO3⁻, NO2⁻, and SO4²⁻, and a positive effect on PO4³⁻, NH4⁺, and EC. This suggested that the tebufenpyrad led to water quality deterioration.
Few studies have been conducted with regard to the effects of insecticides on population dynamics of shrimps and associated groups such as macrophytes, phytoplankton, microorganisms etc. In the present study, effects of a single application of fenoxycarb were tested using indoor freshwater systems dominated by Neocaridina palmata and Ceratophyllum demersum (Dicotyledons: Ceratophyllales). The no observed effect concentration (NOEC) and lowest observed effect concentration (LOEC) for the N. palmata, as scaled by liberated chitobiase, were 6.48 μg/L and 27.76 μg/L, and the dose-related effect lasted for 14 days. Results of principal components analysis (PCA) and that of principal response curves (PRC) method showed that the biomass of C. demersum and concentrations of chlorophyll-a were suppressed, while the concentrations of phycocyanin were promoted. Illumina high-throughput sequencing was adopted to determine the diversity of bacteria and fungi in the media. Result of PCA and PRC showed that the fenoxycarb promoted photosynthetic bacteria (e.g. Cyanobacteria and Rhodobacterales) and suppressed groups involved in nitrogen and sulfur the transformation (e.g. Flavobacterium, hgcI_clade, Cystobasidium, Rhodotorula and Rhizobiales). Promotion in pathogen such as Pseudomonas and Cercozoa and suppression in beneficial taxa such as Novosphingobium and Rhodotorula were also sighted. Result of study suggested a water quality deterioration due to fenoxycarb applications.
Analytical monitoring surveys routinely confirm that organisms in the environment are exposed to complex multi-component pharmaceutical mixtures. We are hence tasked with the challenge to take this into consideration when investigating the ecotoxicology of pharmaceuticals. This review first provides a brief overview of the fundamental approaches for mixture toxicity assessment, which is then followed by a critical review on the empirical evidence that is currently at hand on the ecotoxicology of pharmaceutical mixtures. It is concluded that, while the classical concepts of Concentration Addition and Independent Action (Response Addition) provide a robust scientific footing, several knowledge gaps remain. This includes in particular the need for more and better empirical data on the effects of pharmaceutical mixtures on soil organisms as well as marine flora and fauna, and exploring the quantitative consequences of toxicokinetic, toxicodynamic and ecological interactions. Increased focus should be put on investigating the ecotoxicology of pharmaceutical mixtures in environmentally realistic settings.
Context: Cholinesterase (ChE) had long been employed for revealing environmental existence of anticholinesterases, and β-N-acetylglucosaminidase (NAGase) is a newly developed biomarker of aquatic arthropods. Still, population consequences of ChE inhibition and the consequences in terms of NAGase remained unclear.
Objective: To quantify relationship between level of ChE and that of NAGase deliberated from chemical suppressed population of Daphnia magna.
Methods: A set of macrophyte-dominated systems were established indoor to test insecticide chlorpyrifos. Antibodies were developed for quantifying content of ChE in bodies and content of NAGase in media, which was achieved by indirect-competitive and indirect-noncompetitive enzyme-linked immunosorbent assay (ELISA), respectively.
Results: Lowest observed effect concentration (LOEC) of chlorpyrifos, as it was counted by actual concentrations, was 0.128, <0.011, 0.092, and 0.092 µg/L for population density, inherent activity of ChE, apparent activity of ChE, and content of NAGase, respectively. Corresponding to 0.90–0.48 U/µg declination in inherent activity of ChE, atrophy of −1.65 to 23% in population and that of −4.1 to 24.89% in NAGase was detected, respectively.
Conclusion: Population impact of an anticholinesterase could be predicted, with adequate accuracy, by either ChE or NAGase.
The need for an integrated risk assessment at an ecologically relevant scale (e.g. at the population/community levels) has been acknowledged. Multi‐species systems with increased ecological complexity, however, are difficult if not impossible to reproduce. The laboratory scale microcosm TriCosm (Pseudokirchneriella subcapitata, Ceriodaphnia dubia, Hydra viridissima) of intermediate complexity was developed for the reproducible assessment of chemical effects at the population/community levels. The system dynamics were repeatable in the short term but inter‐experimental variation of algal dynamics in the long term triggered knock on effects on grazer and predator populations. We present 20 experiments to assess the effects of twelve factors (test medium, vessel type/condition, shaking speed, light intensity/regime, inoculation density, medium preparation components, metal concentration/composition, buffering salt type/concentration) on algal growth in the TriCosm enclosure. Growth rates varied between ≤ 0 and 1.40 (± 0.21) and generally were greatest with increased shaking speed, light exposure, medium buffer or aeration time. Treatments conducted in dishes with aseptically prepared, scarcely buffered and/or hardly aerated medium resulted in low growth rates. We found that inter‐experimental variation of algal dynamics in the TriCosm was caused by a modification of medium preparation with the aim of reducing microbial contamination, i.e. the omission of medium aeration. Our findings highlight that consistency in experimental procedures and in‐depth understanding of system components are indispensable to achieve repeatability. This article is protected by copyright. All rights reserved
The phosphonate herbicide glyphosate, which is the active ingredient in the commercial formulation Roundup®, is currently the most globally used herbicide. In aquatic ecosystems, periphytic biofilms, or periphyton, are at the base of food webs and are often the first communities to be in direct contact with runoff. Microcosm experiments were conducted to assess the effects of a pulse exposure of glyphosate on community composition and chlorophyll a concentrations of lake biofilms at different colonization stages (2 months, 1 year, and 20 years). This is the first study that uses such contrasting submersion periods. Biofilms were exposed to either environmental levels of pure analytical grade glyphosate (6 μg/L, 65 μg/L, and 600 μg/L) or to corresponding phosphorus concentrations. Community composition was determined by deep sequencing of the 18S and 16S rRNA genes to target eukaryotes and cyanobacteria, respectively. The results showed that submersion period was the only significant contributor to communi...
Despite the rapid rise in diversity and quantities of engineered nanomaterials produced, the impacts of these emerging contaminants on the structure and function of ecosystems have received little attention from ecologists. Moreover, little is known about how manufactured nanomaterials may interact with nutrient pollution in altering ecosystem productivity, despite the recognition that eutrophication is the primary water quality issue in freshwater ecosystems worldwide. In this study, we asked two main questions: (1) To what extent do manufactured nanoparticles affect the biomass and productivity of primary producers in wetland ecosystems? (2) How are these impacts mediated by nutrient pollution? To address these questions, we examined the impacts of a citrate‐coated gold nanoparticle (AuNPs) and of a commercial pesticide containing Cu(OH)2 nanoparticles (CuNPs) on aquatic primary producers under both ambient and enriched nutrient conditions. Wetland mesocosms were exposed repeatedly with low concentrations of nanoparticles and nutrients over the course of a 9‐month experiment in an effort to replicate realistic field exposure scenarios. In the absence of nutrient enrichment, there were no persistent effects of AuNPs or CuNPs on primary producers or ecosystem productivity. However, when combined with nutrient enrichment, both NPs intensified eutrophication. When either of these NPs were added in combination with nutrients, algal blooms persisted for >50 d longer than in the nutrient‐only treatment. In the AuNP treatment, this shift from clear waters to turbid waters led to large declines in both macrophyte growth and rates of ecosystem gross primary productivity (average reduction of 52% ± 6% and 92% ± 5%, respectively) during the summer. Our results suggest that nutrient status greatly influences the ecosystem‐scale impact of two emerging contaminants and that synthetic chemicals may be playing an under‐appreciated role in the global trends of increasing eutrophication. We provide evidence here that chronic exposure to Au and Cu(OH)2 nanoparticles at low concentrations can intensify eutrophication of wetlands and promote the occurrence of algal blooms.
Biomarkers, defined in ecotoxicology as functional measures of exposure to chemicals, may not be informative on the consequences of exposure at the scale of interest, which is the entire ecosystem. This drawback is because links and interactions existing between these measures and the biological system at a larger scale are not always sufficiently known. In this chapter, three different biomarkers of effect and/or exposure (i) antioxidant enzyme activities (AEA), (ii) community structure and (iii) resistance genes are discussed as potential microbial biomarkers in community ecotoxicology. First, AEA are highly sensitive to chemicals but have low specificity and their link with ecosystems’ health is also unclear. The community composition changes linked to adaptation are highly informative about effects on ecosystems’ health and also sensitive (responding to low but prolonged chemical exposure); however, they are not specific. Finally, resistance genes applicability is very limited since information is lacking about the genes that build resistance to the large list of chemicals of concern. In addition, their ecological implications have only been established for few chemicals, like arsenic. Similarly to investigations focused on organisms with a higher level of biological complexity, microbial biomarkers may not be sufficient to link exposure with ecosystem damage. However, these biomarkers may contribute to providing unequivocal information concerning exposure, early effects, adaptation and ecosystem damage in the framework of integrative multi-metric approaches including other chemical, biogeochemical and ecological metrics related to microbial metabolism such as bioaccumulation, chemical speciation, organic matter decomposition or nutrient cycling.
Depuis sa création en 1998, le parc marin du Saguenay-Saint-Laurent (PMSSL), situé
dans la province du Québec, protège une portion représentative du Saint-Laurent et de son
principal tributaire, le fjord du Saguenay. Dans cette vaste zone côtière, l'étonnante
biodiversité et la complexité des écosystèmes sont confrontées aux activités humaines et à
leurs multiples impacts. Afin de soutenir les gestionnaires du parc marin dans leurs efforts
de conservation, nous avons adapté un modèle de risques relatifs afin de servir d'outil de
gestion pour localiser les zones cumulant le plus de risques environnementaux, identifier
les sources anthropiques de stress impliquées et développer des approches de gestion
permettant de réduire les risques et augmenter le niveau général de protection du parc.
Avant de mettre en place un tel outil, nous nous sommes intéressés aux variables
gouvernant les risques environnementaux dans notre région d'étude et avons procédé à une
mise à jour ciblée des données existantes, nécessaire au développement de notre modèle.
Nous avons d'abord caractérisé les principales sources de contamination terrestre (encore
peu documentées), pour ensuite déterminer le niveau d'exposition des écosystèmes à celles-ci.
Nos résultats ont montré que la contamination du parc était ubiquiste mais distribuée de
manière hétérogène dans les écosystèmes car influencée par la localisation des activités
humaines et des facteurs environnementaux. Plus particulièrement, nous avons identifié les
rejets d'effluents municipaux comme une source importante de contamination au niveau
local mais un vecteur peu important face à la contamination diffuse apportée par le fleuve
Saint-Laurent et la rivière Saguenay. Nous avons estimé la contribution relative de celle-ci
de 88 à 100 % en fonction du contaminant considéré . De plus, une analyse détaillée de la
composition en hydrocarbures aromatiques polycycliques (HAP) nous a permis de mettre
en évidence l'influence du trafic maritime (une source non terrestre) sur la contamination du
parc. Enfin, des données inattendues ont particulièrement retenu notre attention. Dans la
baie Sainte-Marguerite, un site important pour le béluga (une espèce menacée du parc
marin), nous avons enregistré les concentrations en HAP et métaux lourds les plus élevées
du parc marin, en l'absence de source locale de contamination. Notre meilleure hypothèse
repose sur la présence de facteurs hydrodynamiques, influençant le transport et
l'accumulation de contaminant dans ce secteur. Néanmoins, des travaux complémentaires
seront nécessaires pour approfondir la question. Dans leur ensemble, ces résultats nous ont permis de consolider nos connaissances
existantes sur le stress anthropique et ont contribué à une meilleure compréhension des
impacts liés aux activités humaines dans le PMSSL. Nous les avons ensuite intégrés afin de développer notre outil de gestion environnementale. Ce premier déploiement du modèle sur
le territoire du parc nous a permis de tirer un portrait régional des risques dans le parc
marin. Les résultats ont permis d'identifier l'embouchure du fjord ainsi que la zone côtière
de l'estuaire maritime comme les secteurs les plus à risques dans le parc marin et
d'incriminer le trafic maritime, les effluents municipaux et le ruissèlement urbain comme
les sources principales de stress. Grâce à sa flexibilité le modèle peut être utilisé pour
simuler différents scénarios de gestion environnementale. Cette fonctionnalité permet
d'évaluer les bénéfices probables de chaque action potentielle avant de statuer sur la
meilleure approche. Nous avons testé deux options de gestion dans les zones les plus
exposées aux risques du parc: (1) la mise en place de traitements efficaces des effluents
municipaux et (2) une diminution de l'intensité du trafic maritime. Selon les prédictions du
modèle, la mise en application de ces actions environnementales diminuerait le risque
environnemental relatif de 25 à 32 %. Nous recommandons donc aux gestionnaires du
PMSSL de prioriser leurs efforts de gestion sur l'amélioration du traitement des eaux usées
municipales et une meilleure régulation du trafic maritime dans les secteurs de
l'embouchure et de l'estuaire maritime. La souplesse du modèle est finalement une garantie
de la pérennité de notre outil. Celui-ci étant un système ouvert, il sera possibles de réaliser
des optimisations et des mises à jours, au grès des avancés des connaissances scientifiques. -- ABSTRACT: Since its foundation in 1998, the Saguenay-St. Lawrence Marine Park (SSLMP),
located in the Province of Québec, is protecting a significant portion of the St. Lawrence
Estuary and the Saguenay Fjord. In this large coastal area, the important biodiversity and
complexity of the ecosystem are facing human activities and their multiple impacts. In
support to conservation goals, we adapted the relative risk model (RRM) as a management
tool to highlight the zones the most at risk, identify the main sources of stress and develop
environmental strategies to reduce global risk level in the Park.
To build such a model we focussed on variables governing environmental risk in this
marine area and proceeded to an update of the necessary dataset to develop our tool. The
relative significance of main land-based inputs on the global environmental contamination
were first developed and then we examined the chemical and microbial contamination of
several compartments of the ecosystem in the main semi-enclosed bays and streams of the
Saguenay St. Lawrence Marine Park (SSLMP). Our study provided a first estimation of
each source of contamination, particularly local ones, as only a few unpublished data were
previously available. Results showed a ubiquitous contamination but a heterogeneous
distribution of the contamination in the ecosystem of the marine park in relation with the
location of human activities. Particularly, urban effluents were highlighted as an important
source of stress at a local scale but a low contributor to global contamination compared to
diffuse external inputs from the St. Lawrence and Saguenay rivers, which relative
apportionment was estimated from 88 to 100% depending on the analysed pollutant. This
huge discrepancy between sources is mainly driven by their daily discharge but also by
some local hydrodynamic factors discussed in this paper. Moreover, a closer look at the
polycyclic aromatic hydrocarbons (PAH) distribution in intertidal sediments revealed the
influence of maritime traffic. Finally, unexpected data were subject to a special focus. In
the Bay of Sainte-Marguerite, an important site for belugas (endangered species of the
Park), in absence of any local source of contamination, the highest level of contamination
for PAH and some metals was recorded. Some hypotheses are discussed to explain
observations and provide insight for further works on contamination fate in this bay. The information derived from the bulk analysis and multi-contaminant data provided
good insights to enforce our understanding of anthropogenic stress in the SSLMP. Then,
dataset was integrated to develop our tool. This first deployment of the methodology over a
marine conservation area allowed to depict the regional environmental pressure from
multiple anthropogenic sources of stress in the SSLMP. The RRM highlighted the mouth of the Saguenay Fjord and the coastal area of the Lower St. Lawrence Estuary as the subregions
to be the most at risk and incriminated vessel traffic, sewage discharges and urban
runoff as the main sources of stress in those areas. Moreover, the flexibility of this risk
model allowed us to proactively explore future management options (to deal with
environmental risks) and assess their probable benefits. The RRM predicts that the
implementation of wastewater treatment plans (to solve contamination problems) and a
reduction of the navigation pressure would decrease the global risk from 25 to 32% in the
sub-regions identified as the most at risk. Finally, uncertainty and sensitivity analysis was
used to provide preliminary insights on the RRM behaviour and performance, and to assist
in guiding possible fine tuning in the data integration and focusing future studies to
optimize the RRM and its uses.
Embracing energy efficiency (EE) and renewable energy (RE) is essential for improving environmental quality. This research investigates the asymmetric impacts of EE, RE, and other factors on CO2 emissions in BRICS (i.e., Brazil, Russia, India, China, and South Africa) countries from 1990 to 2014. In contrast to previous studies, the present study considers EE as a major cause of CO2 emissions in BRICS countries. By using the new hidden panel cointegration and nonlinear panel autoregressive distributive lag model, this study is the first of its kind that unfolds the asymmetric links among EE, RE, and CO2 emissions. Findings clearly explain that the impact of the selected variables on CO2 emissions is asymmetric, and both EE and RE help to lower CO2 emissions in BRICS countries. In the long run, positive shocks in EE and RE can significantly mitigate CO2 emissions in BRICS economies. In particular, a 1% fluctuation in the positive sum of EE reduces CO2 emissions by 0.783% in the long run. On the other hand, a 1% fluctuation in the positive component of RE reduces CO2 emissions by 0.733%. Moreover, individual country estimates suggest the heterogeneous effects among BRICS countries. Based on the empirical findings, policymakers should consider the asymmetric behavior of the EE, RE, and economic growth while formulating, energy, environment, and growth policies of BRICS countries.
Graphical abstract
The enantioselective environmental behaviors of the chiral insecticide fipronil and its metabolites in lab-scale aquatic ecosystems were studied and the toxicity of fipronil enantiomers and the metabolites to non-target organisms Lemna minor (L. minor) and Anodonta woodiana (A. woodiana) was also investigated in this work. Water-sediment, water-L. minor, water-A. woodiana, and water-sediment-L. minor-A. woodiana ecosystems were set up and exposed to fipronil through a 90-day period. The results showed fipronil could be degraded significantly faster (half-life of 4.6 days) in the complex water-sediment-L. minor-A. woodiana ecosystem. A. woodiana played a crucial role in the dissipation of fipronil, and the microorganisms in the sediment also made great contribution to the degradation of fipronil in aquatic ecosystems. All the three metabolites fipronil desulfinyl, fipronil sulfide and fipronil sulfone were detected in the ecosystems and were more persistent than fipronil. Enantioselective degradation of fipronil was observed with S-fipronil being preferentially degraded in sediment and L. minor, while R-fipronil was metabolized preferentially in A. woodiana. EC50 for L. minor was obtained using 7-day exposure, and for A. woodiana was obtained using 72-h exposure. S-fipronil was more toxic to A. woodiana, while R-fipronil showed higher toxicity to L. minor. Moreover, the three metabolites were found more toxic than fipronil indicating significant environment risks due to their persistence. The present study might have important implications for the risk assessment of fipronil and its metabolites in real aquatic environment.
The influence of roofing material on concentrations of pollutants in roof runoff waters and changes of pollution concentration in time were investigated. In field studies four roofing material types were taken into consideration: ceramic tile, bituminous membrane, asbestos tile, and zinc sheeting. Samples were collected from November 2007 to March 2008. Anions, cations, metals, PAHs, pesticides, and PCBs were determined. The existence of the first flush phenomenon for most pollutants was confirmed, with concentrations up to two orders of magnitude higher in first flush compared to steady state conditions. Time trends of pollutant concentration changes were observed. Additionally, analysis of a series of samples collected from naelting snow accumulated on the roof showed an increase of organic pollutant concentrations during thaw.
The sections in this article are
Introduction to Key Aspects of Ecotoxicology
Protection Goals and Assessment Endpoints
Structure and Function in Ecosystems
Diversity of Sensitivity in Ecosystems
Hazard Assessment and Uncertainty
Environmental Fate and Pathways of Exposure to Chemicals in the Environment
Properties Affecting Bioavailability
Properties Affecting Bioconcentration and Biomagnification
Absorption, Distribution, Metabolism, and Excretion of Chemicals
Modeling Exposure
Mechanisms of Toxic Action
Properties Affecting Toxicity
Modeling Toxicity
Examples of Methods That Can Be Used in Designing Chemicals with Reduced Ecological Risks
Fluorinated Surfactants
Pesticides
Designing Pesticides for Lack of Persistence
Designing Specific Isomers to Reduce Risk in the Environment
Developing Pesticides That Are More Specific to the Target Organism
Ranking and Prioritizing Pesticides in Terms of Risk to the Environment
Pharmaceuticals
Macro‐ and Micro‐Contaminants Produced During Manufacture
Overview, Conclusions, and the Path Forward
The environmental behavior and stereoselectivity of the chiral fungicide benalaxyl and its chiral metabolite benalaxyl acid in water, sediment, and water-sediment microcosms were studied. The microcosms were incubated at 25 °C with light or under darkness. The influencing factors such as light and microorganism were investigated. The results showed that benalaxyl had half-lives of >21 days in the microcosm system and that the metabolite benalaxyl acid could exist in the microcosm for >70 days. Benalaxyl was mainly transformed through microbial degradation, and thus sediment microorganisms played a major role in the dissipation of benalaxyl in the aquatic microcosm. The stereoselective behavior of benalaxyl and benalaxyl acid was also investigated. (-)-Benalaxyl was preferentially degraded in the microcosm, resulting in an enrichment of the more toxic enantiomer (+)-benalaxyl, which may cause higher risk to the aquatic system. Moreover, (-)-benalaxyl acid was preferentially formed in the microcosm. The enantioselectivity of the enantiomers in the microcosm should be taken into consideration for an accurate risk assessment.
Embora os Copepoda de agua doce geralmente possuam estreitas faixas de tolerância aos fatores ambientais e sejam particularmente sensiveis aos contaminantes contidos na coluna d’agua, estes sao raramente utilizados como organismos-teste em estudos ecotoxicologicos. O objetivo deste trabalho foi avaliar a toxicidade aguda do agrotoxico fipronil utilizando como organismo-teste a especie de Copepoda de agua doce, Mesocyclops meridianus . Os organismos foram coletados na Represa do Lobo (Broa), Sao Paulo, SP. Para o teste, a solucao controle e as solucoes-teste (0,156 mg.L -1 , 0,312 mg.L -1 , 0,625 mg.L -1 e 1,25 mg.L -1 ) foram realizadas com quatro repeticoes para cada uma. Foram colocados cinco individuos de M. meridianus em cada cavidade da placa de acrilico. Os recipientes-teste foram mantidos em incubadora a 24 ± 1 °C com fotoperiodo de 16 horas luz : 8 horas escuro durante o periodo de 48 h de exposicao ao agrotoxico. A mortalidade observada apos este periodo foi utilizada para a determinacao da CL 50 . Para tal calculo, utilizou-se o programa estatistico “Trimmed Spearman-Karber Method for Estimating Median Lethal Concentrations in Toxicity Biossays”. O fipronil foi considerado altamente toxico para M. meridianus durante a exposicao de 48 h e o valor da CL 50 – 48h foi de 0,99 mg L -1 . Analisando-se os resultados deste e de outros estudos observou-se que as especies de Copepoda de agua doce apresentam grande sensibilidade a diferentes agentes toxicos. A especie Mesocyclops meridianus apresentou alta sensibilidade ao agrotoxico fipronil e por ser de facil manipulacao laboratorial pode ser um organismo-teste em estudos futuros de ecotoxicologia.
Analytical monitoring surveys routinely confirm that organisms in the environment are exposed to complex multi-component pharmaceutical mixtures. We are hence tasked with the challenge to take this into consideration when investigating the ecotoxicology of pharmaceuticals. This review first provides a brief overview of the fundamental approaches for mixture toxicity assessment, which is then followed by a critical review on the empirical evidence that is currently at hand on the ecotoxicology of pharmaceutical mixtures. It is concluded that, while the classical concepts of concentration addition and independent action (response addition) provide a robust scientific footing, several knowledge gaps remain. This includes, in particular, the need for more and better empirical data on the effects of pharmaceutical mixtures on soil organisms as well as marine flora and fauna, and exploring the quantitative consequences of toxicokinetic, toxicodynamic and ecological interactions. Increased focus should be put on investigating the ecotoxicology of pharmaceutical mixtures in environmentally realistic settings.
© 2014 The Author(s) Published by the Royal Society. All rights reserved.
I experimentally determined fertilizer exposure effects on caddisfly (Trichoptera) mortality, behavior and leaf decomposition. Few studies have specifically examined fertilizer impacts on caddisflies and none have conducted experimental manipulations within a controlled laboratory setting. Caddisfly survivorship decreased as fertilizer concentration increased. Contact frequency between caddisfly larvae and larvae position on the leaf, followed a unimodal curve in relation to a fertilizer concentration gradient. Findings also confirm the findings of previous studies on leaf decomposition in relation to caddisfly mortality. The removal of the experimental setup from a natural site is a novel experimental approach and has significant implications for standards of water quality monitoring using aquatic macroinvertebrates.
A wide range of agrochemicals can be applied in a peanut production system to control various stresses and manage crop growth and development. Field and laboratory experiments were conducted in North Carolina to define biological and physicochemical interactions when insecticides (fenpropathrin and lambda-cyhalothrin) or plant growth regulator (prohexadione calcium) were applied in combination with other agrochemicals including fungicides, herbicides, and micronutrients. Fenpropathrin or lambda-cyhalothrin combinations did not injure peanut in 2008 and 2009. Two sprays of prohexadione calcium improved row visibility and reduced main stem height compared with one prohexadione calcium spray irrespective of agrochemical combinations. In many instances, applying prohexadione calcium with other agrochemicals resulted in lower main stem height compared to prohexadione calcium alone. In one of the experiments, prohexadione calcium with prothioconazole plus tebuconazole lowered fall army worm population compared with prohexadione calcium alone. Addition of boron, manganese, and 2,4-DB to fenpropathrin, lambda-cyhalothrin, and prohexadione calcium combinations changed solution pH dramatically. Prohexadione calcium had the least effect on pH of the carrier.
In this report new proposals for the aquatic effects assessment of plant protection products (pesticides) in the Netherlands are described for edge-of-field surface waters (drainage ditches) falling under the domain of the Plant Protection Product Regulation (pre-registration) and for water bodies falling under the domain of the Water Framework Directive (post-registration). These methods are developed on request of two Dutch ministries (Ministry of Economic Affairs, Agriculture and Innovation; Ministry of Infrastructure and Environment). They are based on specific protection goals proposed by the responsible risk managers of the Dutch ministries, the current European aquatic risk assessment procedures for plant protection products, state-of-the-art knowledge on the ecotoxicology of these chemicals and different aims/claims of the Plant Protection Product Regulation (1107/2009/EC) and the Water Framework Directive (2000/60/EC).
This chapter summarizes field and laboratory investigations dealing with metals and pesticides (90) and emerging compounds’ (10) effects on fluvial communities. The Arkansas River case study is a good example showing how field observations, together with long-term natural experiments and microcosm experiments, provide consistent evidence of metals effects on macroinvertebrate communities. In the case of biofilms, microcosm and mesocosm experiments confirm that metals and pesticides are responsible for the loss of sensitive species in the community, and that this influence is modulated by several biological and environmental factors. Information about the effects of emerging pollutants is very scarce, highlighting the existence of a missing gap requiring future investigations. The examples provided and the recommendations given are proposed as a general guide for studies aiming to link chemical pollution with ecological alterations.
This paper deals with prospective and retrospective ecological risk assessment (ERA) procedures for pesticides in surface waters as performed under European legislation (Regulation 1107/2009/EC; Directive 2009/128/EC; Directive 2000/60/EC). Priorities to improve the aquatic risk assessment and management of pesticides are discussed on basis of the following five theses: The management of the environmental risks of pesticides in surface water requires an appropriate implementation of feedback mechanisms between prospective and retrospective ERA. An appropriate ERA cannot be performed without well-defined specific protection goals, described in terms of focal vulnerable populations and related exposure assessment goals. The interaction between the assessment of exposure and eco(toxico)logical effects in ERA is at a lower level of sophistication than either assessment of exposure or assessment of effects in the field. There is insufficient experimental proof that, in prospective ERA, the chronic effect assessment procedures accurately predict long-term population- and community-level impacts. Multiple stress by pesticides in aquatic ecosystems cannot be ignored in ERA, but in individual water bodies toxicity usually is dominated by a limited number of substances. Integr Environ Assess Manag © 2013 SETAC.
This review includes works published in the general scientific literature during 2009 on the effects of anthropogenic pollutants on freshwater organisms. It begins with two broad sections: research reviews and broad field studies and surveys. This is followed by reviews of research categorized in sections to reflect the pollutant class. These sections include wastewater, stormwater and non-point source pollution, nutrients, metals, persistent organic pollutants, pharmaceuticals, endocrine disruptors, pesticides, petroleum hydrocarbons and polycyclic aromatic hydrocarbons (PAHs), ionic liquids, and nanomaterials. The final section includes works describing innovations in the field of freshwater pollution research.
We studied the fate and bioavailability of insecticides in short-term experiments (48 h) with different hydrophobicity (3.8 pM carbofuran, 3.0 pM lindane, and 5.3 pM chlorpyrifos) across gradients in dissolved organic matter (low-, medium-, and high-DOM) in freshwater microcosms, mimicking runoff events of pesticides. The effects of biofilms were studied by including treatments with biofilms cultivated under different DOM-concentrations. The presence of biofilms negatively affected chlorpyrifos water concentrations, indicating rapid sorption of this hydrophobic pesticide, while lindane concentrations instead increased and carbofuran concentrations were unaffected. Associations of lindane and chlorpyrifos with biofilms were 1.6-2.0 times higher in low- and high-DOM than in medium-DOM treatments, indicating that sorption was affected not only by the quantity, but also by the quality of DOM. Although the proportion of pesticides recovered in biofilms was consistently less than 1 % of added pesticide, pesticide concentrations in biofilms were on average more than 75- (carbofuran) and 382-times (lindane) higher than those in water. Snail accumulation of all three pesticides was significantly affected by DOM-concentrations and correlated to pesticide hydrophobicity, but the relationships were not straightforward. For example, carbofuran uptake in treatments without biofilms was higher in low-DOM than in medium- and high-DOM treatments, while chlorpyrifos uptake instead increased across the DOM-gradient. Biofilms played a role only for the uptake of chlorpyrifos, which decreased markedly in the presence of biofilms. Bioconcentration factors (BCF) calculated for snails and biofilms differed for the three pesticides and were related to their sorption behaviour (i.e., hydrophobicity). The relative proportion of pesticide uptake through biofilm consumption was consistently less than 2 %, showing that passive uptake was by far the predominant uptake pathway for all three pesticides.
In this report new proposals for the aquatic effects assessment of plant protection products (pesticides) are described that may be used within the context of the Dutch pre- and post-registration risk assessment procedures for plant protection products. Decision schemes are described for edge-of-field surface waters (drainage ditches) and water bodies that fall under the domain of the Water Framework Directive. The decision schemes are developed on request of two Dutch ministries (Ministry of Economic Affairs, Agriculture and Innovation; Ministry of Infrastructure and Environment). In addition, these decision schemes are based on specific protection goals proposed by the responsible risk managers of the Dutch ministries, the current European aquatic risk assessment procedures for plant protection products, state-of-the-art knowledge on the ecotoxicology of these chemicals and different aims/claims of the Plant Protection Product Regulation (1107/2009/EC) and the Water Framework Directive (2000/60/EC).
Keywords: Pesticides; Water organisms; Ecological risks; Ecotoxicology; Regulation 1107/2009/EC; Water Framework Directive.
Standard species used in ecological risk assessment are chosen based on their sensitivity to various toxicants and the ease of rearing them for laboratory experiments. However, this mostly overlooks the fact that species in the field that may employ variable life-history strategies, which may have consequences concerning the vulnerability of such species to exposure with contaminants. We aimed to highlight the importance of copepods in ecology and to underline the need to include freshwater copepods in ecotoxicology. We carried out a literature search on copepods and Daphnia in ecology and ecotoxicology to compare the recognition given to these two taxa in these respective fields. We also conducted a detailed analysis of the literature on copepods and their current role in ecotoxicology to characterize the scale and depth of the studies and the ecotoxicological information therein. The literature on the ecology of copepods outweighed that in ecotoxicology when compared with daphnids. Copepods, like other zooplankton, were found to be sensitive to toxicants and important organisms in aquatic ecosystems. The few studies that were conducted on the ecotoxicology of copepods mainly focused on marine copepods. However, very little is known about the ecotoxicology of freshwater copepods. To enable a more realistic risk higher tier environmental risk assessment, we recommend considering freshwater copepods as part of the hazard assessment process. This could include the establishment of laboratory experiments to analyse the effects of toxicants on copepods and the development of individual-based models to extrapolate effects across species and scenarios.
In this paper a novel multivariate method is proposed for the analysis of community response data from designed experiments repeatedly sampled in time. The long-term effects of the insecticide chlorpyrifos on the invertebrate community and the dissolved oxygen (DO)–pH–alkalinity–conductivity syndrome, in outdoor experimental ditches, are used as example data. The new method, which we have named the principal response curve method (PRC), is based on redundancy analysis (RDA), adjusted for overall changes in community response over time, as observed in control test systems. This allows the method to focus on the time-dependent treatment effects. The principal component is plotted against time, yielding a principal response curve of the community for each treatment. The PRC method distills the complexity of time-dependent, community-level effects of pollutants into a graphic form that can be appreciated more readily than the results of other currently available multivariate techniques. The PRC method also enables a quantitative interpretation of effects towards the species level.
This article describes the long-term effects on the macro invertebrate and zooplankton community in outdoor experimental ditches after a single application of the insecticide chlorpyrifos. Nominal concentrations of 0.1, 0.9, 6, and 44 μg/L of chlorpyrifos were applied to two mesocosms each, while four served as controls. Both macroinvertebrates and zooplankton were sampled from 4 weeks before to 55 weeks after treatment. The macroinvertebrate and zooplankton data sets were combined into one data set and analyzed using the multivariate ordination technique “redundancy analysis.” The method provided a clear description of the effects on the invertebrate community in time while still showing the effects at the species level. Crustacea and Insecta showed a rapid, concentration-dependent decrease in numbers after insecticide application (direct effects). An increase in gastropods and Oligochaeta was found, suggesting indirect effects. The start of recovery of the invertebrate populations affected was found to depend not only on the susceptibility of the taxa but also on ecological characteristics, such as the length of the life cycle. A no-observed-effect concentration of 0.1 μg/L could be derived both at the species and the community level. Safe concentrations, based on no-observed-short-term-effect levels for some characteristic indigenous taxa susceptible to chlorpyrifos, also appeared to protect the total invertebrate community in the long term. The invertebrate community at all treatment levels was considered to have recovered after 24 weeks posttreatment.
In this article we present a review of the laboratory and field toxicity of herbicides to aquatic ecosystems. Single-species acute toxicity data and (micro)mesocosm data were collated for nine herbicides. These data were used to investigate the importance of test species selection in constructing species sensitivity distributions (SSDs), and in estimating hazardous concentrations ( i.e ., HC5) protective for freshwater aquatic ecosystems. A lognormal model was fitted to toxicity data (acute EC50s and chronic NOECs) and the resulting distribution used to estimate lower (95% confidence), median (50% confidence), and upper (5% confidence), HC5 values. The taxonomic composition of the species assemblage used to construct the SSD does have a significant influence on the assessment of hazard and only sensitive primary producers should be included for the risk assessment of herbicides. No systematic difference in sensitivity between standard and non-standard test species was observed. Hazardous concentrations estimated using laboratory-derived acute and chronic toxicity data for sensitive freshwater primary producers were compared to the response of herbicide-stressed freshwater ecosystems using a similar exposure regime. The lower limit of the acute HC5 and the median value of the chronic HC5 were protective of adverse effects in aquatic micro/mesocosms even under a long-term exposure regime. The median HC5 estimate based on acute data was protective of adverse ecological effects in freshwater ecosystems when a pulsed or short-term exposure regime was used in the microcosm and mesocosm experiments. There was also concordance between the predictions from the effect model PERPEST and the concentrations at which clear effects started to emerge in laboratory and field studies. However, compared to the SSD concept, the PERPEST model is able to provide more information on ecological risks when a common toxicological mode of action is evaluated as it considers both recovery and indirect effects.
The rate of conversion of chlorophyll-a to phaeophytin-a in dilute acid organic solvents is markedly pH-dependent. The widely used spectrophotometric measurement before and after acidification to discriminate between chlorophyll-a and phaeopigments is applicable only between pH 2.6—2.8. At higher pH the reaction proceeds slowly and occasionally may be incomplete. At lower pH complicating reactions may occur, such as breakdown of certain carotenoid pigments causing (time-dependent) increase of background absorption, and formation of di-cations of phaeophytin with spectral characteristics different from the usually obtained mono-cations of phaeophytin. Consequently, it is stressed to control carefully the acid concentration, the water content of the solvent, and the amount of MgCO3 used in the filtration procedure. In general, for the purpose of spectrophotometric acidification experiments, acidification by dilute hydrochloric acid added to organic solvents containing 10—20% water, and omission of MgCO3 would be preferable.
On the basis of observed complications in the red part of the absorption spectrum of the pigment extract, it is recommended to use the above stated pH-range.
Experiments in microcosms and mesocosms, which can be carried out in an advanced tier of risk assessment, usually result in large data sets on the dynamics of biological communities of treated and control cosms. Multivariate techniques are an accepted tool to evaluate the community treatment effects resulting from these complex experiments. In this paper two methods of multivariate analysis are discussed on their merits: 1) the canonical ordination technique Principal Response Curves (PRC) and 2) the similarity indices of Bray-Curtis and Stander. For this, the data sets of a microcosm experiment were used to simultaneously study the impact of nutrient loading and insecticide application. Both similarity indices display, in a single graph, the total effect size against time and do not allow a direct interpretation down to the taxon level. In the PRC method, the principal components of the treatment effects are plotted against time. Since the species of the example data sets, react in qualitatively different ways to the treatments, more than one PRC is needed for a proper description of the treatment effects. The first PRC of one of the data sets describes the effects due to the chlorpyrifos addition, the second one the effects as a result of the nutrient loading. The resulting principal response curves jointly summarize the essential features of the response curves of the individual taxa. This paper goes beyond the first PRC to visualize the effects of chemicals at the community level. In both multivariate analysis methods the statistical significance of the effects can be assessed by Monte Carlo permutation testing.
Twelve indoor, plankton-dominated, freshwater microcosms (600 l) were used to study the effect of a mixture of herbicides on structural and functional aspects of these ecosystems. The EC50, 72 h values of the most susceptible standard test alga Selenastrum capricornutum (EC50, atrazine=54 μg l−1, EC50, diuron=15 μg l−1, EC50, metolachlor=56 μg l−1) were used as a starting point for the dosage applied in the microcosms (dosages: 0, 0.01, 0.03, 0.1, 0.3, 1× EC50). The microcosms were exposed to chronic levels for 28 days and subsequently monitored for 4 more weeks.
The following effects were observed: (1) direct effects became apparent from an initial drop in photosynthesis efficiency, pH and oxygen concentration and a decrease in the abundance of several phytoplankton taxa at the 0.3 × EC50 treatment level and higher. (2) Fourteen days post application an increase in the abundance of several phytoplankton taxa (Chlamydomonas sp. and Stephanodiscus/Cyclotella) was observed; oxygen concentrations recovered while alkalinity, conductivity and total inorganic nitrogen were elevated. (3) Effects on fauna were minor. Daphnia galeata showed a decreasing trend and the cyclopoid copepods an increasing trend at the end of the experiment.
Multivariate statistical analyses demonstrated no effects of any treatment level on the zooplankton community. Effects were reported for the phytoplankton community at dose levels of 0.3 × EC50 and higher. On species level the most sensitive taxon was Chlorophyceae coccales. For this taxon a NOEC at the dose level of 0.01 × EC50 was calculated. This effect however was relatively small in magnitude and merely based on an increase in numbers in the control and lowest treated microcosms rather than a decrease in numbers in all other treatments. The standards based on algal toxicity data, as adopted by the Uniform Principles, consist of a safety factors of 0.1 to be multiplied with the EC50. The NOEC of coccales was lower than 0.1 × EC50. All other observed variables in this aquatic ecosystem were sufficiently protected against the mixture of herbicides by the safety factor as proposed in the Uniform Principles.
In freshwater model ecosystems nutrient additions resulted in significant short-term increases in periphyton biomass. Effects of applications of both nutrients and the insecticide chlorpyrifos caused a larger and more prolonged increase in periphytic algae. After three to four weeks this bloom of periphytic algae was controlled by non-arthropod grazers, which increased in numbers after insecticide application. The study indicates that the top-down control of periphyton by grazers is an important regulatory mechanism in macrophyte-dominated aquatic ecosystems. Insecticides, by poisoning arthropod grazers, may indirectly stimulate periphytic algae, as long as resources and non-arthropod grazers permit this.
A literature review of freshwater model ecosystem studies with insecticides was performed to assess the NOEC ecosystem for individual compounds, to compare these threshold levels with water quality standards, and to evaluate the ecological consequences of exceeding these standards. Studies were judged appropriate for this purpose if the test systems simulated a realistic freshwater community, if the experimental design was generally sound (ANOVA or regression design; exposure concentrations described), and if published not earlier than 1980. Most studies dealt with organophosphates (predominantly single applications) and synthetic pyrethroids (mostly repeated applications) in standing waters. Structural endpoints were more sensitive than functional ones. The most sensitive taxa were representatives of the crustaceans, insects and fish. Most studies tested relatively high concentrations, with even lowest concentrations showing effects. An NOEC eco could therefore be established for a limited number of compounds only. Based on toxic units, safe threshold values were more or less the same for compounds with a similar mode of action. This also accounted for the nature and magnitude of direct effects at higher concentrations. Usually, indirect effects were reported at higher concentrations than those for direct effects. Although laboratory single species toxicity tests may not allow predictions on (exact) ecological effects, some generalizations on direct effects and recovery can be made with respect to the acute EC50 of the most sensitive standard test species. Safe concentrations, as set for water quality standards, appear to be protective. Depending on exposure regime, the NOEC eco is generally in the range of (0.1-0.01) x EC50 of the most sensitive standard test species. Recovery of sensitive endpoints usually takes place within two months after the last application when peak concentrations stay lower than (0.1-1) x EC50 of the most sensitive standard test species.
The fate of the insecticide Dursban 4E (active ingredient chlorpyrifos) and its effect on crustaceans and insects was studied in indoor experimental freshwater ecosystems that intended to mimick drainage ditches. A single dose (simulating aerial drift) was applied to achieve nominal chlorpyrifos concentrations of 5 or 35 micrograms/L. Two experiments were performed, one in which all model ecosystems were dominated by the macrophyte Elodea nuttallii, and one using systems devoid of macrophytes. In macrophyte-dominated systems, Elodea vegetation adsorbed a large proportion of the dose applied and hampered the mixing of the insecticide in the water (at least up till day 8). Only a small proportion became incorporated in the sediment. In open water systems the insecticide was rapidly mixed in the water, and the sediment played a very significant role as sink for chlorpyrifos. In both Elodea-dominated and open water systems 50% of the dose applied had disappeared on day 8 post-treatment. The rate of disappearance of chlorpyrifos was relatively rapid in water and macrophytes, and relatively slow in the sediment. Of the arthropods in the zooplankton Cladocera were more susceptible than Copepoda. Significant effects (p less than or equal to 0.05) on Cladocera occurred relatively late in Elodea-dominated systems (in week 4 post-application) in contrast to open water systems (week 1), which is in accordance with the observed differences in the fate of chlorpyrifos. Daphnia pulex, D. longispina and Simocephalus vetulus recovered in the model ecosystems when chlorpyrifos concentrations were lower than 0.1-0.2 micrograms/L, which is in agreement with results of laboratory protocol tests performed with these cladocerans. Among the macroscopic Arthropoda the apparent order of susceptibility was amphipods greater than insects greater than isopods. The isopod Asellus aquaticus was more sensitive to the application of the insecticide than the closely related species Proasellus coxalis. In treated open water systems the latter even increased significantly in numbers. Cage experiments in the model ecosystems performed with several species of Arthropoda indicate that laboratory protocol tests may give a reasonable prediction of short-term direct effects of chlorpyrifos for the same species inhabiting more complex aquatic systems.
This paper reports on the chronic effects of a mixture of the insecticides chlorpyrifos and lindane in freshwater microcosms. Chronic treatment levels corresponding to concentrations of 0, 0.005, 0.01, 0.05, 0.1 and 0.5 times the LC50 of the most sensitive standard test organism were evaluated. The zooplankton community structure was altered from the 0.05 * LC50 treatment level upwards. Cladocerans were the most susceptible group, followed by Copepoda and Ostracoda. Rotifera increased in abundance at the higher treatment levels. Increased abundance of some phytoplankton taxa and increased chlorophyll-a levels were found at the two highest treatment levels, most probably a consequence of decreased grazing pressure. Threshold levels for the mixture, both at population and community/ecosystem level, corresponded well with those reported in the literature for the individual compounds. The overall risk assessment indicates no antagonistic or synergistic effects of the mixture at ecosystem level. It was found that the safety factors set by the Uniform Principles for individual compounds also ensure protection against chronic exposure to a mixture of insecticides at community level, though not always at species level.
Testing of single chemicals with single species is common ecotoxicological practice in contrast to contaminated environments where highly diverse biological communities are exposed to highly diverse mixtures of chemical compounds. We, therefore, investigated whether mixture toxicity approaches that have been used successfully for single species, might also be applied on a community level of biological complexity. Twelve inhibitors of photosystem II, selected by QSAR and chemometrical approaches as the structurally most similar from a congeneric group of phenylurea herbicides, were tested singly and as mixtures on two types of marine microalgal communities, periphyton and epipsammon. Inhibition of photosynthesis was measured in short-term tests using incorporation of radiolabelled carbon (14C) to estimate photosynthetic rates. Two basic concepts, concentration addition (CA) and independent action (IA), were used to predict the toxicities of the mixtures. Congeneric and similar-acting substances such as the phenylureas are expected to comply with CA rather than IA. The aim of the present study was to evaluate whether these concepts can be used to predict mixture toxicity also to periphyton and epipsammon photosynthesis, i.e. at the level of natural communities. We found that deviations between observed and predicted mixture toxicity were relatively small but that CA predictions were the more accurate ones. The predictions proved to be robust, when based on single substance information even from different seasons, years, and sites. We conclude that the concept of CA for predicting mixture toxicity applies also at the community level of algal testing; at least when a physiological short-term effect indicator is used that matches the mechanism of action of the substances.
A literature review of freshwater (model) ecosystem studies with neurotoxic insecticides was performed to assess ecological threshold levels, to compare these levels with the first tier approach within European Union (EU) administration procedures, and to evaluate the ecological consequences of exceeding these thresholds. Studies published between 1980 and 2001 were reviewed. Most studies covered organophosphates and synthetic pyrethroids in lentic waters. The most sensitive taxa were representatives of crustaceans, insects and fish. Based on toxic units, threshold values were equivalent for compounds with a similar mode of action. This also accounted for the nature and magnitude of direct effects at higher concentrations. Although laboratory single species toxicity tests may not allow predictions on precise ecological effects, some generalisations on effects and recovery can be made with respect to acute standard laboratory EC50 data. The NOEC(ecosystem) usually is a factor of 10 or more higher than first tier acceptable concentrations, particularly in the case of single applications and acetylcholinesterase inhibitors. Acceptable concentrations, as set by the EU first tier approach, appear to be protective. Recovery of sensitive endpoints usually occurs within 2 months of the (last) application when peak concentrations remain lower than (0.1-1) x EC50 of the most sensitive standard test species. The consistency of response patterns found in model ecosystem studies can be useful when estimating the ecological risks of pesticides. The use of an effect classification system was also helpful in evaluating effects.
The toxicity of three antifoulants (Sea-Nine, Irgarol, and TBT) was determined individually and in mixtures in two tests with microalgae. Effects on periphyton community photosynthesis and reproduction of the unicellular green algae Scenedesmus vacuolatus were investigated. The tested antifoulants were highly toxic in both tests. Observed mixture toxicities were compared with predictions derived from two concepts: Independent Action (IA), assumed to be more relevant for the tested mixtures that were composed of dissimilarly acting substances, and Concentration Addition (CA), regarded as a reasonable worst-case approach in predictive mixture hazard assessment. Despite the corresponding mechanistic basis, IA failed to provide accurate predictions of the observed mixture toxicities. Results show the same pattern in both assays. Mixture effects at high concentrations were slightly overestimated and effects at low concentrations were slightly underestimated. Maximum observed deviations between observed and IA-predicted concentrations amount to a factor of 4. The suggested worst-case approach using CA was protective only in effect regions above 20%. Nevertheless, the application of any concept that accounts for possible mixture effects is more realistic than the present chemical-by-chemical assessment.
In this paper a novel multivariate method is proposed for the analysis of community response data from designed experiments repeatedly sampled in time. The long-term effects of the insecticide chlorpyrifos on the invertebrate community and the dissolved oxygen (DO)-pH-alkalinity-conductivity syndrome, in outdoor experimental ditches, are used as example data. The new method, which we have named the principal response curve method (PRC), is based on redundancy analysis (RDA), adjusted for overall changes in community response over time, as observed in control test systems. This allows the method to focus on the time-dependent treatment effects. The principal component is plotted against time, yielding a principal response curve of the community for each treatment. The PRC method distills the complexity of time-dependent, community-level effects of pollutants into a graphic form that can be appreciated more readily than the results of other currently available multivariate techniques. The PRC method also enables a quantitative interpretation of effects towards the species level.
Experimental ponds received single additions of the herbicide atrazine in concentrations of 20 and 500 @mg/L, and were compared to control ponds for 136 d. Atrazine is an inhibitor of photosynthesis, and both concentrations depressed phytoplankton growth in the ponds within a few days. This was followed by successional changes leading to the establishment of species of phytoplankton more resistant to inhibition by atrazine. Laboratory studies verified this resistance and verified effects on other species at concentrations of atrazine as low as 1-5 @mg/L. When and to what extent resistant species appeared in the phytoplankton communities differed with treatment. At the atrazine concentration of 500 @mg/L, there was a delayed appearance but eventually a greater biomass and persistent of these species. The grazing zooplankton influenced these differences and were in turn affected by them. Natural interactions such as competition and predation among the species of the communities greatly affected their responses to the toxic chemical. The importance of atrazine as an environmental pollutant is suggested by these responses to concentrations of 1-5 @mg/L, which are common downstream in many agricultural watersheds, 20@mg/L, which is the high level found in these waters, and 500 @mg/L, which is the high level found in waters directly adjacent to treated fields.
The paper assesses the usefulness of the concept of ‘concentration addition’ (CA) for describing the joint effect of pesticides on aquatic organisms, based on literature data from 1972 to 1998. For more than 90% of 202 mixtures in 26 studies, CA was found to predict effect concentrations correctly within a factor of two. Although from a theoretical point of view the assumption of CA may be invalid when dealing with mixtures of compounds with dissimilar modes of action, the experimental results have usually been indistinguishable from that predicted by CA. Deviations from CA did occur, but were mostly limited in extent. Upward and downward deviations from CA were of comparable magnitude and frequency, and tended to cancel each other out. The combinations identified as most frequently leading to deviations from CA were those of an organophosphorus ester or a carbamate with either another organophosphorus ester or a synthetic pyrethroid.© 2000 Society of Chemical Industry
Twelve indoor, plankton-dominated, freshwater microcosms (600 l) were used to study the effect of a mixture of herbicides on structural and functional aspects of these ecosystems. The EC50, 72 h values of the most susceptible standard test alga Selenastrum capricornutum (EC50, atrazine=54 μg l-1, EC50, diuron=15 μg l-1, EC50, metolachlor=56 μg l-1) were used as a starting point for the dosage applied in the microcosms (dosages: 0, 0.01, 0.03, 0.1, 0.3, 1× EC50). The microcosms were exposed to chronic levels for 28 days and subsequently monitored for 4 more weeks.The following effects were observed: (1) direct effects became apparent from an initial drop in photosynthesis efficiency, pH and oxygen concentration and a decrease in the abundance of several phytoplankton taxa at the 0.3 × EC50 treatment level and higher. (2) Fourteen days post application an increase in the abundance of several phytoplankton taxa (Chlamydomonas sp. and Stephanodiscus/Cyclotella) was observed; oxygen concentrations recovered while alkalinity, conductivity and total inorganic nitrogen were elevated. (3) Effects on fauna were minor. Daphnia galeata showed a decreasing trend and the cyclopoid copepods an increasing trend at the end of the experiment.Multivariate statistical analyses demonstrated no effects of any treatment level on the zooplankton community. Effects were reported for the phytoplankton community at dose levels of 0.3 × EC50 and higher. On species level the most sensitive taxon was Chlorophyceae coccales. For this taxon a NOEC at the dose level of 0.01 × EC50 was calculated. This effect however was relatively small in magnitude and merely based on an increase in numbers in the control and lowest treated microcosms rather than a decrease in numbers in all other treatments. The standards based on algal toxicity data, as adopted by the Uniform Principles, consist of a safety factors of 0.1 to be multiplied with the EC50. The NOEC of coccales was lower than 0.1 × EC50. All other observed variables in this aquatic ecosystem were sufficiently protected against the mixture of herbicides by the safety factor as proposed in the Uniform Principles.
During the production of the pesticide lindane (γ-hexachlorocyclohexane; γ-HCH), large quantities of byproducts, like the α-, β-, and δ-HCH isomers, were discarded at dump sites. β-HCH was found to be extremely persistent in the environment under aerobic conditions. We studied the degradation of this isomer under methanogenic conditions in a flow-through column packed with polluted sediment. β-HCH was completely removed in this system. Chlorobenzene was detected in the effluent as a product. A β-HCH transforming anaerobic enrichment culture was obtained in batch cultures by using the column material as inoculum. δ-2,3,4,5-Tetrachlorocyclohexene is proposed as an intermediate during transformation, while benzene and chlorobenzene were formed as stable end products. The enrichment culture was also able to dechlorinate α-HCH at a comparable rate and γ- and δ-HCH at lower rates. Dechlorination was inhibited by the addition of vancomycin, but not by the addition of bromoethanesulfonic acid. Pasteurization inhibited dechlorination completely. This is the first detailed description of the biodegradation of β-HCH, including intermediate and end product identification, under defined anaerobic conditions.
This discussion paper presents a framework for spatiotemporal differentiation in ecological protection goals to assess the risks of pesticides in surface waters. It also provides a proposal to harmonize the different scientific approaches for ecotoxicological effect assessment adopted in guidance documents that support different legislative directives in the European Union (Water Framework Directive and Uniform Principles). Decision schemes to derive maximum permissible concentrations in surface water are presented. These schemes are based on approaches recommended in regulatory guidance documents and are scientifically underpinned by critical review papers concerning the impact of pesticides on freshwater organisms and communities. Special attention is given to the approaches based on standard test species, species sensitivity distribution curves, and model ecosystem experiments. The decision schemes presented here may play a role in the “acceptability” debate and can be used as options in the process of communication between risk assessors and risk managers as well as between these risk experts and other stakeholders.
The ecological risk of pesticides is estimated from data generated on single chemicals. However, agricultural chemicals frequently occur in the environment as herbicide and insecticide mixtures. This study investigated the effects of an herbicide and insecticide mixture in 0.1-ha mesocosms to determine if the herbicide would alter the bioavailability of the insecticide to fish and zooplankton. Mesocosms were treated with either 0 or 50 g/L atrazine (six mesocosms each) to create two levels of herbicide classification. A series of six concentrations of the pyrethroid insecticide esfenvalerate (0–1.71 g/L) was applied on two dates within each herbicide level (0 or 50 g/L). Atrazine altered species composition of macrophytes but did not alter plant biomass, total system metabolism, or the bioavailability of the insecticide to zooplankton or fish. Potential ecological synergisms (i.e., increased effects of the insecticide due to the herbicide) did not occur because of the functional redundancy of the macrophyte community and the rapid aqueous dissipation rate of the pyrethroid insecticide.
Pond mesocosms were used to assess the effects of a widely used pesticide on a natural plankton community. Atrazine, whose residuals in surface waters can occur at levels potentially hazardous to aquatic organisms, was applied at six test concentrations during a 6-week study. Structural and functional parameters were measured twice a week.
Oxygen concentration was the most sensitive parameter, with marked reductions indicating adverse affects by atrazine on photosynthesis. Taxa in the phytoplankton community showed varying sensitivity to the pollutant, although threshold concentrations for effects on most taxa were exceeded at 182 μg/L. Indirect effects due to food limitation were the most likely cause of changes in the abundance of several zooplankton species.
It is concluded that mesocosms provide realistic effects of atrazine on aquatic systems, but at the same time some difficulties with this approach are apparent when applied to seasonally dynamic planktonic systems.
Effects of a chronic application of the herbicide Afalon (active ingredient linuron) on physicochemical conditions, decomposition of plant litter, and densities of zooplankton and macroinvertebrates were studied in indoor microcosms intended to model drainage ditches. For 28 days, concentrations of 0, 0.5, 5, 15, 50, and 150 μg/L linuron were maintained, each in two replicates. The microcosms were dominated by the macrophyteElodea nuttallii.The functional response of the ecosystem is discussed in relation to shifts in community structure. Treatment effects of linuron on community metabolism, as a direct effect of the inhibition of the photosynthesis of macrophytes and algae, resulted in a decrease in dissolved oxygen and pH, and an increase in alkalinity and conductivity (NOEC 0.5 μg/L). During the posttreatment period, differences between controls and highest dose fell gradually, but were still significant 7 weeks after the start of linuron application. Decomposition of particulate organic material in litter bags was not affected, despite decreases in DO. The negative effect of linuron on several algae (cryptophytes, diatoms) and the positive effect on the green algaChlamydomonasresulted in a decrease of several Rotatoria and an increase in Copepoda, and, to a lesser extent, Cladocera. The complete disappearance of the macrophyteE. nuttalliiin the 150 μg/L microcosms and a 50% reduction of its biomass in the 50 μg/L microcosms reduced the numbers of the snailPhysella acuta,which normally inhabits macrophytes. Artificial substrates indicated a significant increase in the isopodAsellus aquaticusin the 50 and 150 μg/L microcosms during the posttreatment period. This, however, was counteracted by a significant decrease inA. aquaticusat the final harvest. Changes in the ecosystem structure (decline in macrophyte biomass) made the artificial substrates more attractive.
The paper assesses the usefulness of the concept of`concentrationof`concentration addition' (CA) for describing the joint effect of pesticides on aquatic organisms, based on literature data from 1972 to 1998. For more than 90% of 202 mixtures in 26 studies, CA was found to predict effect concentrations correctly within a factor of two. Although from a theoretical point of view the assumption of CA may be invalid when dealing with mixtures of compounds with dissimilar modes of action, the experimental results have usually been indistinguishable from that predicted by CA. Deviations from CA did occur, but were mostly limited in extent. Upward and downward deviations from CA were of comparable magnitude and frequency, and tended to cancel each other out. The combinations identi®ed as most frequently leading to deviations from CA were those of an organophosphorus ester or a carbamate with either another organophosphorus ester or a synthetic pyrethroid.
Effects of chronic application of the fungicide Derosal(R) (active ingredient carbendazim) were studied in indoor macrophyte-dominated freshwater microcosms. The concentrations (0, 3.3, 33, 100, 330 and 1000 microg/l) were kept at a constant level for 4 weeks. This paper is the second of a series of two; it describes the effects on zooplankton and primary producers and presents an overall discussion. The zooplankton community was negatively affected by the three highest treatment levels (NOEC(community)=33 microg/l). At higher treatment levels Cladocera taxa were completely eliminated, while Copepod numbers were reduced. Rotatoria taxa decreased (Keratella quadrata and Lecane sp.) or increased in abundance (Testudinella parva) at the highest treatment level only. Due to the reduced grazing pressure, the abundance of some phytoplankton taxa and the chlorophyll-a content of the phytoplankton increased at the three highest treatment levels (NOEC(community)=33 microg/l). This effect was not observed for the periphyton, most probably because the reduced grazing pressure was compensated by the increased abundance of some snail species such as Lymnaea stagnalis and Physella acuta. At the end of the experimental period the biomass of the macrophyte Elodea nuttallii was significantly elevated at the two highest treatment levels. It is hypothesised that carbendazim might have caused, directly or indirectly, the removal of pathogene organisms from the macrophyte.
This discussion paper presents a framework for spatiotemporal differentiation in ecological protection goals to assess the risks of pesticides in surface waters. It also provides a proposal to harmonize the different scientific approaches for ecotoxicological effect assessment adopted in guidance documents that support different legislative directives in the European Union (Water Framework Directive and Uniform Principles). Decision schemes to derive maximum permissible concentrations in surface water are presented. These schemes are based on approaches recommended in regulatory guidance documents and are scientifically underpinned by critical review papers concerning the impact of pesticides on freshwater organisms and communities. Special attention is given to the approaches based on standard test species, species sensitivity distribution curves, and model ecosystem experiments. The decision schemes presented here may play a role in the ¿acceptability¿ debate and can be used as options in the process of communication between risk assessors and risk managers as well as between these risk experts and other stakeholders.
The aim of this paper is an evaluation of isobolograms, a method proposed for the assessment of combined effects of chemicals. In order to examine potentials and shortcomings of this approach for ecotoxicological purposes, algal biotests with selected pesticidal compounds were performed. Additivity, as defined by the model, is demonstrated for the combination of atrazine and metribuzin for different combination ratios, response levels, and parameters. Subadditivity is shown for amitrole and glufosinate-ammonium. The results and inherent biometrical features are discussed in terms of criteria considered suitable for comparative evaluation of biometrical models for the assessment of mixtures of chemicals.
A multispecies toxicity test system using naturally derived microbial communities on polyurethane foam substrates was used to evaluate the toxic effects of the herbicide atrazine. Both structural (e.g., protozoan species number, biomass) and functional (e.g., colonization rate, oxygen production) community responses were measured. Oxygen production and the ability of communities to sequester magnesium and calcium were the most sensitive measures of toxic stress due to atrazine (maximum allowable toxicant concentrations [MATCs]=17.9 µg/L). Dissolved oxygen was 33% lower, and there was 15% less calcium and magnesium in communities at and above 32.0 µg/L atrazine compared to controls. Species richness and estimates of biomass (total protein and chlorophyll a) were less sensitive (MATCs=193) to atrazine. At the highest atrazine concentration (337 µg/L), species numbers were 30% lower than controls, and protein and chlorophyll a content of communities were reduced by 38 and 91%, respectively. Low levels of atrazine (3.2–32.0 µg/L) resulted in a 46% increase in species numbers and a greater concentration of total protein and chlorophyll a (41 and 57%, respectively). Results compared well with other estimates of chronic toxicity for effects of atrazine on aquatic communities. Reported MATCs ranged from 70.7 to 3,400 µg/L. The results from this test emphasize the importance of monitoring both structural and functional measures of community integrity in toxicity testing with multispecies.
The comparison of dose treatment means with a control mean to determine the lowest dose level at which there is evidence for a difference from control was discussed recently (Williams [1971]). A test procedure was proposed for the case when all treatments are equally replicated. The primary purpose of this paper is to give results which enable the test to be used when the treatment replications are unequal. A two-sided version of the test is also described and the Type I errors of the test are discussed.
A system of six outdoor artificial streams (dimensions 5.0 X 0.35 X 0.25 m) was used to study the biological effects of lindane in flowing water. Lindane was continuously applied during 28 days to four of the streams while two were left as untreated controls. The nominal concentrations were 4.0, 8.0, 16.0, and 32.0 micrograms liter-1 and the mean measured concentrations of lindane in stream water over 28 days were 3.1, 5.7, 11.1, and 20.3 micrograms liter-1. Effects were observed on population densities of the freshwater shrimp Gammarus pulex, drift of G. pulex and mayflies (Baetis spp.), and on community photosynthesis. An increase in photosynthetic production of oxygen, a result of increased periphyton standing crop, followed the loss of macroinvertebrates, via drift, from the treated streams. This established a clear link between a direct effect of lindane on macroinvertebrates and an indirect effect on periphyton production. Drift and community photosynthesis were the most sensitive of the biological parameters measured and effects were detected in all treated streams. During a 28-day experiment with lower concentrations of lindane, nominally 0.25 and 1.0 micrograms liter-1, there were minor effects on the drift of Baetis spp. but only at the higher concentration. There were no detected effects on population densities or on community photosynthesis. Results from the two experiments provided a measured no observed effect concentration for lindane of 0.2 micrograms liter-1 and the threshold concentration for sustained effects on the stream communities was in the range 0.8 to 3.1 micrograms liter-1.
Effects of lindane on natural planktonic communities were investigated in aquatic indoor microcosms. Lindane was dosed to eight 300-liter microcosms for 2 weeks, and effects and recovery processes were monitored over 12 weeks. Mean measured water concentrations of lindane during the exposure period were 3, 6, 13, 27, 55, 102, 230, and 455 micrograms/liter. Zooplankton was severely affected by lindane. The most sensitive organisms were nauplii of copepodes which were affected at all treatment levels > or = 6 micrograms/liter during exposure (Days 2-14). Recovery of nauplii abundance was concentration-dependent at concentrations < or = 55 micrograms/liter lindane, whereas at concentrations > or = 102 micrograms/liter recovery was negligible. Cladocera abundance decreased during exposure to > or = 102 micrograms/liter lindane and did not recover to original levels until the end of the study. For phytoplankton, decreased population densities of Chlorophyceae and microalgae ( < 5 microns) were observed at lindane concentrations < or = 55 micrograms/liter, where zooplankton was only temporarily affected. At higher lindane, concentrations ( > or = 102 micrograms/liter) effects on phytoplankton were not clear, as also increases in abundances were observed, probably as a consequence of minimized grazing pressure, due to high zooplankton mortality. Comparison of these results with data obtained in complex outdoor systems demonstrates the practicability and sensitivity of indoor microcosms and emphasizes the importance of long-term testing and assessment of recovery processes for prediction of environmental effects.