Ökotoxikologie: Ökosystemare Ansätze und Methoden, 1999
This study, based on two examples, demonstrates that intraspecific stress between individuals of ... more This study, based on two examples, demonstrates that intraspecific stress between individuals of one species alters the sigmoid concentration-response relation-ships. A high intraspecific stress due to high population density can reduce the survival in the control. However, stress due to xenobiotica is reducing the intraspecific stress. As a consequence, test systems with high intra-specific stress are less sensitive to xenobiotic stress than systems with low intraspecific stress. According to the tests conditions, the NOEC can differ of some orders of magnitude and the concentration-response curve shows a modified slope. It is, thus, important to consider the degree of intraspecific interaction in the design and interpretation of test-systems as this can partly compensate the effects of xenobiotica. Since intraspecific stress is an integral property of natural populations, it is expected that they react less to xenobiotica than test-systems with low intra-specific interaction.
Global pesticide exposure in agriculture leads to biodiversity loss, even at ultra-low concentrat... more Global pesticide exposure in agriculture leads to biodiversity loss, even at ultra-low concentrations below the legal limits. The mechanisms by which the effects of toxicants act at such low concentrations are still unclear, particularly in relation to their propagation across the different biological levels. In this study, we demonstrate, for the first time, a cascade of effects from the gene to the community level. At the gene level, agricultural pesticide exposure resulted in reduced genetic diversity of field-collected Gammarus pulex, a dominant freshwater crustacean in Europe. Additionally, we identified alleles associated with adaptations to pesticide contamination. At the individual level, this genetic adaptation to pesticides was linked to a lower fecundity, indicating related fitness costs. At the community level, the combined effect of pesticides and competitors caused a decline in the overall number and abundance of pesticides susceptible macroinvertebrate competing with gammarids. The resulting reduction in interspecific competition provided an advantage for pesticide-adapted G. pulex to dominate macroinvertebrate communities in contaminated areas, despite their reduced fitness due to adaptation. These processes demonstrate the complex cascade of effects, and also illustrate the resilience and adaptability of biological systems across organisational levels to meet the challenges of a changing environment.
Short pulses of toxicants can cause latent effects that occur long after the contamination event ... more Short pulses of toxicants can cause latent effects that occur long after the contamination event and are currently unpredictable. Here, we introduce an analytical framework for mechanistically predicting latent effects considering interactive effects of multiple stressors and hormetic effect compensation. We conducted an extensive investigation using high temporal resolution microcosm data of the mayfly Cloeon dipterum exposed to the pyrethroid pesticide esfenvalerate for 1 h. For 6 pesticide concentrations and 3 food levels we identified daily general stress information and predicted their synergistic interactions using the Stress Addition Model (SAM). Our analysis revealed that, especially at low concentrations, latent effects contributed most to the overall effect. At low concentrations ranging from 1/100 to 1/10,000 of the acute LC50 , resulting in a 30–15 % mortality, latent effects prevailed, accounting for 92 % to 100 % of the observed effects. Notably, the concentration causing 15 % mortality 29 days post-exposure was 1000 times lower than the concentration causing the same mortality 4 days post-exposure, emphasizing the time-dependent nature of this Latent-Effect-Amplification (LEA). We identified both acute mortality and latent effects of pesticides on emergence. Furthermore, we observed pesticide-induced compensation mechanisms at both individual and population levels, transforming the initial monotonic concentration-response relationship into a hormetic, tri-phasic response pattern. Combining these processes enabled a quantification of the underlying causes of latent effects. Our findings highlight that short-term pesticide exposures can lead to latent effects of particular significance, especially at low effect concentrations.
Monitoring for pesticides in surface waters can be problematic. These substances are generally di... more Monitoring for pesticides in surface waters can be problematic. These substances are generally diffuse and transient pollutants and are often present at low concentrations. Difficulties in monitoring for pesticides makes attributing any observed changes in a biological community to pesticide contamination complicated. An indicator that would allow us to diagnose pesticide contamination at a site would be very useful.
A review of current biological indicators shows the SPEAR approach to be one of the most promising bioindicator methods to detect pesticide contamination in lotic ecosystems (Schriever et al. 2008). The SPEAR approach has been used to show a link between levels of insecticide and fungicide exposure and stream macroinvertebrate community structure. As the SPEAR approach is based on species traits it is not restricted to use in one geographic area, and it has been successfully applied in different biogeographical regions in Europe. It was therefore proposed that the pesticide-specific SPEAR indicator should be revised for use in England and Wales for possible inclusion in routine Environment Agency monitoring.
The SPEAR concept is currently the only trait-based approach to identify species vulnerable to pesticide contamination. The approach is based on species sensitivity to organic toxicants and life-cycle traits responsible for potential exposure and recovery (generation time, migration ability, presence of aquatic stages during maximum pesticide exposure), and classifies the species into “species at risk” and “species not at risk” according to these traits. The existing SPEAR indicator is based on information on macroinvertebrates from mainland Europe. Although this may be directly applicable in the UK, adaptation and revision was desirable for a more efficient application of the method in this geographical region. In particular, the trait database required some limited revision and updating with UK species and ecological information from this region.
The existing SPEAR indicator is based on species-level data. Much of the macroinvertebrate data collected by the Environment Agency is at a family level. It was therefore necessary to develop a family-level SPEAR indicator and to establish whether the family-level tool remained sensitive enough to indicate pesticide exposure.
In summary, the aim of this study was to revise and update the SPEAR database for use in the UK and to compare the SPEAR indices based on species and family levels of taxonomic identification using data sets for other European regions (Finland, France, and Germany).
Revision of the database resulted in addition of 38 new taxa. For 125 taxa, UK-specific ecological information was included in the database as separate region-specific entries. For 54 taxa information on ecological traits was corrected, but not defined as UKspecific. Sixty-six out of all 152 families in the database were defined as families at risk for UK conditions. The updated database (Liess et al. 2008) now contains most of the UK stream macroinvertebrate taxa together with information about their respective ecological traits.
Statistical comparison of the SPEAR indexes based on family and species levels of taxonomic resolution has shown that the family-level index can be effectively used to detect pesticide contamination in streams. The effect of upstream recovery areas and levels of seasonal variability were similar for both the family and species level indexes. The predictive power of the family-level index is expected to be only slightly lower than that of the species-level index. Taking into account the time-consuming nature, cost and difficulties of species-level identification, the family-level index is a promising and cost-effective bioindicator tool for detecting pesticide contamination in streams. Future application of the SPEAR approach in the UK requires validation in field investigations. A field survey programme, including assessment of exposure and effect, should be performed to validate the SPEAR approach for UK conditions.
The agricultural use of pesticides leads to environmentally relevant pesticide concentrations tha... more The agricultural use of pesticides leads to environmentally relevant pesticide concentrations that cause adverse effects on stream ecosystems. These effects on invertebrate community composition can be identified by the bio-indicator SPEARpesticides. However, refuge areas have been found to partly confound the indicator. On the basis of three monitoring campaigns of 41 sites in Central Germany, we identified 11 refuge taxa. The refuge taxa, mainly characterized by dispersal-based resilience, were observed only nearby uncontaminated stream sec- tions and independent of the level of pesticide pressure. Through incorporation of this information into the re- vised SPEARpesticides indicator, the community structure specifically identified the toxic pressure and no longer depended on the presence of refuge areas. With regard to ecosystem functions, leaf litter degradation was pre- dicted by the revised SPEARpesticides and the median water temperature at a site (R2 = 0.38, P = 0.003). Further- more, we designed the bio-indicator SPEARrefuge to quantify the magnitude of general recolonization at a given stream site. We conclude that the taxonomic composition of aquatic invertebrate communities enables a specific indication of anthropogenic stressors and resilience of ecosystems.
Pesticide applications in agricultural crops often comprise a mixture of plant protection product... more Pesticide applications in agricultural crops often comprise a mixture of plant protection products (PPP), and single fields face multiple applications per year leading to complex pesticide mixtures in the environment. Restricted to single PPP, the current European Union PPP regulation, however, disregards the ecological risks of pesticide mixtures. To quantify this additional risk, we evaluated the contribution of single pesticide active ingredients to the additive mixture risk for aquatic risk indicators (invertebrates and algae) in 464 different PPP used, 3446 applications sprayed and 830 water samples collected in Central Europe, Germany. We identified an average number of 1.3 different pesticides in a single PPP, 3.1 for complete applications often involving multiple PPP and 30 in stream water samples. Under realistic worst-case conditions, the estimated stream water pesticide risk based on additive effects was 3.2 times higher than predicted from single PPP. We found that in streams, however, the majority of regulatory threshold exceedances was caused by single pesticides alone (69% for algae, 81% for invertebrates). Both in PPP applications and in stream samples, pesticide exposure occurred in repeated pulses each driven by one to few alternating pesticides. The time intervals between pulses were shorter than the
Under global change scenarios, multistress conditions may occur regularly and require adaptation.... more Under global change scenarios, multistress conditions may occur regularly and require adaptation. However, the adaptation to one stressor might be associated with the increased sensitivity to another stressor. Here, we investigated the ecological consequences of such trade-off under multiple stress. We compared the pesticide tolerance of the crustacean Gammarus pulex from agricultural streams with populations from reference streams. Under optimum temperature, G. pulex from agricultural streams were considerably more tolerant to pesticides as compared to the reference populations. Here, we assume that the increased tolerance in agricultural populations is the combination of acclimation, epigenetic effect, and genetic evolution. After experimental pre-exposure to very low concentration (LC 50 / 1000), reference populations showed increased pesticide tolerance. In contrast, pre-exposure did not further increase the tolerance of agricultural populations. Moreover, these populations were more sensitive to elevated temperature alone due to the hypothesized fitness cost of genetic adaptation to pesticides. However, both reference and agricultural populations showed a similar tolerance to the combined stress of pesticides and warming due to stronger synergistic effects in adapted populations. As a result, pesticide adaptation loses its advantage. The combined effect was predicted well using the stress addition model, developed for predicting the synergistic interaction of independent stressors. We conclude that under multistress conditions, adaptation to pesticides reduces the general stress capacity of individuals and trade-off processes increase the sensitivity to additional stressors. This causes strong synergistic effects of additional stressors on pesticide-adapted individuals.
Background: Pesticides are washed from agricultural fields into adjacent streams, where even shor... more Background: Pesticides are washed from agricultural fields into adjacent streams, where even short-term exposure causes long-term ecological damage. Detecting pesticide pollution in streams thus requires the expensive monitoring of peak concentrations during runoff events. Alternatively, exposure and ecological effects can be assessed using the SPEAR pesticides bioindicator that quantifies pesticide-related changes in the macroinvertebrate community composition. SPEAR pesticides has been developed in Central Europe and validated in other parts of Europe, Australia and South America; here we investigated its performance in East African streams. Results: With minimal adaptations of the SPEAR pesticdes index, we successfully characterized pesticide pollution in 13 streams located in Western Kenya. The East African SPEAR pesticides index correlated well with the overall toxicity of 30 pesticides (maximum toxic unit = maximum environmental vs. median lethal concentration) measured in stream water (R 2 = 0.53). Similarly, the SPEAR pesticides index correlated with the risk of surface runoff from agricultural fields (as identified based on ground slope in the catchment area and the width of protective riparian strips, R 2 = 0.45). Unlike other bioindicators designed to indicate general water pollution, SPEAR pesticides was independent of organic pollution and highly specific to pesticides. In 23% of the streams, pesticides exceeded concentrations considered environmentally safe based on European first tiered risk assessment. Conclusions: Increasing contamination was associated with considerable changes in the macroinvertebrate community composition. We conclude that pesticides need to be better regulated also in developing countries. SPEAR pesticides provides a straightforward and cost-efficient tool for the required monitoring of pesticide exposure in small to medium streams.
Ecological effects Recovery stream sections. These factors proved to be stronger predictors for t... more Ecological effects Recovery stream sections. These factors proved to be stronger predictors for the recovery than the pesticide tolerance. We revealed that the biological indicators SPEARpesticides and share of Ephemeroptera, Plecoptera and Trichoptera (EPT) are not suitable for the identification of such extreme events, when nearly all taxa are eradicated. Both indicators are functioning only when repeated stressors initiate long-term competitive replacement of sensitive by insensitive taxa. We conclude that pesticide spills can have significant long-term effects on stream macroinvertebrate communities. Regular ecological monitoring is imperative to identify such ecosystem impairments, combined with analytical chemistry methods to identify the potential sources of spills.
Background: The European environmental risk assessment of plant protection products considers aqu... more Background: The European environmental risk assessment of plant protection products considers aquatic model ecosystem studies (microcosms/mesocosms, M/M) as suitable higher tier approach to assess treatment-related effects and to derive regulatory acceptable concentrations (RAC). However, it is under debate to what extent these artificial test systems reflect the risks of pesticidal substances with potential harmful effects on natural macroinvertebrate communities, and whether the field communities are adequately protected by the results of the M/M studies. We therefore compared the composition, sensitivity and vulnerability of benthic macroinvertebrates established in control (untreated) groups of 47 selected M/M studies with natural stream communities at 26 reference field sites. Results: Since 2013 the number of benthic macroinvertebrate taxa present in M/M studies has increased by 39% to a mean of 38 families per study. However, there is only an average of 4 families per study that comply with the recommendations provided by EFSA (EFSA J 11:3290, 2013), i.e.: (i) allowing statistical identification of treatmentrelated effects of at least 70% according to the minimum detectable difference (here criteria are slightly modified) and (ii) belonging to insects or crustaceans (potentially sensitive taxa for pesticidal substances). Applying the criterion of physiological sensitivity according to the SPEAR pesticides concept, the number of families decreases from 4 to 2.3 per study. Conclusions: Most taxa established in recent M/M studies do not suitably represent natural freshwater communities. First, because their abundances are often not sufficient for statistical detection of treatment-related effects in order to determine an appropriate endpoint and subsequent RAC. Recommendations are given to improve the detectability of such effects and their reliability. Second, the taxa often do not represent especially sensitive or vulnerable taxa in natural communities in terms of their traits. The uncertainties linked to vulnerable taxa in M/M studies are especially high considering their representativity for field assemblages and the comparability of factors determining their recovery time. Thus considering recovery for deriving a RAC (i.e., ERO-RAC) is not recommended. In addition, this paper discusses further concerns regarding M/M studies in a broader regulatory context and recommends the development of alternative assessment tools and a shift towards a new paradigm.
Following agricultural application, pesticides can enter streams through runoff during rain event... more Following agricultural application, pesticides can enter streams through runoff during rain events. However, little information is available on the temporal dynamics of pesticide toxicity during the main application period. We inves- tigated pesticide application and large scale in-stream monitoring data from 101 agricultural catchments obtained from a Germany-wide monitoring from April to July in 2018 and 2019. We analysed temporal patterns of pesticide application, in-stream toxicity and exceedances of regulatory acceptable concentrations (RAC) for over 70 pesticides. On a monthly scale from April to July, toxicity to invertebrates and algae/aquatic plants (algae) obtained with event- driven samples (EDS) was highest in May/June. The peak of toxicity towards invertebrates and algae coincided with the peaks of insecticide and herbicide application. Future monitoring, i.e. related to the Water Framework Directive, could be limited to time periods of highest pesticide applications on a seasonal scale. On a daily scale, toxicity to inver- tebrates from EDS exceeded those of grab samples collected within one day after rainfall by a factor of 3.7. Within two to three days, toxicity in grab samples declined compared to EDS by a factor of ten for invertebrates, and a factor of 1.6 for algae. Thus, toxicity to invertebrates declined rapidly within 1 day after a rainfall event, whereas toxicity to algae remained elevated for up to 4 days. For six pesticides, RAC exceedances could only be detected in EDS. The exceedances of RACs coincided with the peaks in pesticide application. Based on EDS, we estimated that pesticide ex- posure would need a 37-fold reduction of all analysed pesticides, to meet the German environmental target to keep RAC exceedances below 1 % of EDS. Overall, our study shows a high temporal variability of exposure on a monthly but also daily scale to individual pesticides that can be linked to their period of application and related rain events.
Aquatic communities are exposed to repeated pulses of toxicants and environmental stressors. We h... more Aquatic communities are exposed to repeated pulses of toxicants and environmental stressors. We hypothesize that the dose, order, and timing of stress events shape the interactions of these communities. For this, we conducted a fully-crossed, four-factorial, multiple stress exposure experiment to study the combined effects of Esfenvalerate and ultraviolet-B (UV-B) radiation related to the exposure timing and order on Daphnia magna. We revealed that initial exposure to low stress doses, independent of the stress type (UV-B or Esfenvalerate), significantly increased the resistance toward the second stressor. This beneficial effect was apparent only when the second stressor was applied immediately after the first stressor (p < 0.01). When the period between stressor applications was extended to 2 days, the antagonism between the two stressors turned into synergism. The stressor interaction could be predicted with an abstract-mechanistic model of the temporal dynamics of the early-stage stress response. With this model, the timing and order of exposures were able to successfully explain interactions observed in all treatments (model-R 2 = 1.0). We conclude that especially the duration of a break between exposures and the exposure dose has a decisive influence on interactions between toxicants and environmental stressors.
Vegetated buffer strips (VBS) are an effective measure to retain pesticide inputs during rain eve... more Vegetated buffer strips (VBS) are an effective measure to retain pesticide inputs during rain events. Numerous studies have examined the retention effects of VBS on pesticides. However, no study has addressed on a large scale with event-related peak concentrations how wide the VBS should be to avoid ecological impacts on aquatic life. Here, we investigated for 115 lowland stream sections in Germany the relevance of environmental and physico-chemical parameters to determine the instream pesticide concentration and their ecological risks. Based on peak concentrations related to rain events with precipitation amount resulting in VBS relevant surface runoff for 30 of the 115 investigated stream sections (25 to 70 mm/d), we demonstrated that the average width of VBS was the main parameter (R 2 = 0.38) reducing the pesticide input ratio, indicating a relevant proportion of surface runoff contributing to the total in-stream pesticide concentrations. Additionally, dry ditches within agricultural fields increased pesticide input (R 2 = 0.31). Generally, substances classified as slightly mobile were better retained by VBS than mobile substances. Other factors including slope, land use and vegetation cover of VBS had only a minor influence. We assessed the ecological risk of in-stream pesticide concentrations by quantifying exceedances of regulatory-(RAC) and field-validated acceptable concentrations (AC field). We then translated this ecological risk into protective VBS width by calculating the quotient of in-stream concentration and threshold (RQ). We estimate that a VBS width of 18 m is sufficient to meet the RQ ACfield protection goal for 95% of streams. The presence of dry ditches increased the protective VBS width to 32 m. In current agricultural practice, however, 26% of the water stretches investigated do not comply with the prescribed 5 m VBS. An extension of the VBS area to 18 m would demand 3.8% of agricultural land within the catchments. A 50% reduction in pesticide use, as required by the European green deal, would still result in 39% (RAC) and 68% (AC field) of event-related samples being exceeded. Consequently, we see the extension of the VBS width as the most efficient mearsure to sustainably reduce pesticide concentrations in small streams.
The Water Framework Directive (WFD) demands that good status is to be achieved for all European w... more The Water Framework Directive (WFD) demands that good status is to be achieved for all European water bodies. While governmental monitoring under the WFD mostly concludes a good status with regard to pesticide pollution, numerous scientific studies have demonstrated widespread negative ecological impacts of pesticide exposure in surface waters. To identify reasons for this discrepancy, we analysed pesticide concentrations measured in a monitoring campaign of 91 agricultural streams in 2018 and 2019 using methodologies that exceed the requirements of the WFD. This included a sampling strategy that takes into account the periodic occurrence of pesticides and a different analyte spectrum designed to reflect current pesticide use. We found that regulatory acceptable concentrations (RACs) were exceeded for 39 different pesticides at 81% of monitoring sites. In comparison, WFD-compliant monitoring of the same sites would have detected only eleven pesticides as exceeding the WFD-based environmental quality standards (EQS) at 35% of monitoring sites. We suggest three reasons for this underestimation of pesticide risk under the WFD-compliant monitoring: (1) The sampling approach - the timing and site selection are unable to adequately capture the periodic occurrence of pesticides and investigate surface waters particularly susceptible to pesticide risks; (2) the measuring method - a too narrow analyte spectrum (6% of pesticides currently approved in Germany) and insufficient analytical capacities result in risk drivers being overlooked; (3) the assessment method for measured concentrations - the protectivity and availability of regulatory thresholds are not sufficient to ensure a good ecological status. We therefore propose practical and legal refinements to improve the WFD’s monitoring and assessment strategy in order to gain a more realistic picture of pesticide surface water pollution. This will enable more rapid identification of risk drivers and suitable risk management measures to ultimately improve the status of European surface waters.
Biological indices aim to reflect the ecological quality of streams based on the community's spec... more Biological indices aim to reflect the ecological quality of streams based on the community's species or trait composition. Accordingly, the capability to predict the ecological quality depends on (i) the knowledge on the association of taxa or traits with stressors and (ii) the taxonomic and quantitative resolution of taxa. Generally speaking, a higher resolution is associated with a better linkage between environmental condition and biological response but also with higher efforts and costs. So far it is unknown how the taxonomic and quantitative resolution affect the ecological quality assessment of streams related to pesticide effects when applying the invertebrate-based indicator SPEARpesticides. We investigated the ecological quality of 101 streams considering four taxonomic levels (species, genus, family, order) and three quantitative resolutions (abundance, three abundance classes, and presence-absence). In a multiple linear regression analysis between 13 investigated stressors and SPEARpesticides, the full models' explained variance remained fairly constant with decreasing taxonomic and quantitative resolution. As expected, the highest association between pesticide pressure and SPEARpesticides was reached at a species/abundance resolution yielding an R2 of 0.43. In contrast, the lowest quantitative resolution of order level combined with presence-absence information revealed an explained variance of 0.28 R2. We suggest the family/abundance class resolution (R2 = 0.38) as the best trade-off between effort and accuracy for large-scale monitoring. Due to a comparable linear regression at family/abundance class resolution, the assigned ecological quality classes were largely congruent (69 %) to species/abundance resolution. We conclude that the ecological quality assessment with SPEARpesticides at family/abundance class resolution can be used to link pesticide contamination and invertebrate community structure with less taxonomic expertise and less quantification effort.
Bulletin of Environmental Contamination and Toxicology, 2001
The community inhabiting a body of water represents the "ecological memory" of the habitat, and h... more The community inhabiting a body of water represents the "ecological memory" of the habitat, and hence the composition of aquatic communities is used to monitor various stressors. A prerequisite for the development of useful indicator systems is that the species be ranked in order of their sensitivity to the stress parameter of interest. In the case of toxic xenobiotics, no existing classifications of aquatic macroinvertebrate species according to their specific sensitivities are sufficiently comprehensive to allow these organisms to be used as indicators for contamination of the water. However, this is precisely the area in which community-based indicator systems are particularly de-sirable. This is because precise information about contamination via chemical analysis of water samples is often difficult to obtain and laborious (Liess et al. 1999). Changes in aquatic communities, as a consequence of exposure to test substances, can be examined by contamination of experimental mesocosms. The results have repeatedly shown that, while various characteristics of the individual species tested are influential, the most important is the animal's specific physiological sensitivity to the contaminant in the acute toxicity test (Van den Brink et al. 1996; Sherratt et al. 1999). Therefore, the ranking of species should be based on the results of toxicity tests. For most species, however, hardly any information about their sensitivities is available (Notenboom et al 1995). Thus, what is required, is a comprehensive compilation of sensitivities at such a taxonomic level, that from known species sensitivities, inferences can be made about species not yet subjected to toxicity tests.
Results of environmental risk assessments based merely on toxic effects of contaminants at the in... more Results of environmental risk assessments based merely on toxic effects of contaminants at the individual level, without consideration of population-level effects, may be questionable. The aim of the present study was to investigate how limited food resources, resulting in intraspecific competition, could interact with the chronic effect of short-term contamination with the insecticide esfenvalerate. Larvae of the mayfly, Cloeon dipterum, were exposed to esfenvalerate (0.001-100 g/L) for 1 h and then transferred to indoor microcosms containing insecticide-free water, where they were maintained at various food levels until emergence. The results showed that short-term exposure to 10 or 100 g/L resulted in acute mortality. Chronic effects on survival occurred at concentrations up to three orders of magnitude lower than that causing the acute effect (0.01 g/L). Food limitation increased effects on organisms during medium-term observation (8-15 d), but assessment of long-term survival rates suggested that the chronic effects of low insecticide concentrations could be compensated for, at least regarding some endpoints. The authors assume that in limited-food conditions, lethal and sublethal effects reduced competition between individuals, resulting in significantly increased final survival.
The study aims to evaluate the impact of insecticides associated with rainfall-induced surface ru... more The study aims to evaluate the impact of insecticides associated with rainfall-induced surface runoff from arable land on macroinvertebrate populations. These effects of insecticides were distinguished from the hydraulic stress also associated with surface runoff. Transient increase in discharge and insecticide contamination (maximum 6 g/L parathion-ethyl in stream water, 302 g/L fenvalerate in suspended particulates) was observed in a headwater stream subsequent to surface runoff from arable land. In the aquatic macroinvertebrate community, eight of the eleven abundant species disappeared, and the remaining three were reduced significantly in abundance following the insecticide-contaminated runoff. Recovery within 6 months was observed for four species and recovery within 11 months for nine species. Two species remained at a low population density for over a year. The effects of insecticides were distinguished from other parameters, such as hydraulic stress associated with surface runoff, as well. The causal connection between insecticide contamination and biological response was established by eliminating increased hydraulic stress during surface runoff using in-parallel bypass microcosms containing the dominant species Gammarus pulex and Limnephilus lunatus. The mortality of these species was similar to that of the same species in the stream. Additional microcosms, disconnected from the stream during runoff events, served as a control. Thus, the toxic potential of the runoff water is considered to be responsible for the observed effect on the macroinvertebrates. It is concluded that agricultural insecticide input may alter the dynamics of macroinvertebrate communities in streams.
The ecological effects of surface water runoff on the macroinvertebrate community in a ditch with... more The ecological effects of surface water runoff on the macroinvertebrate community in a ditch with an agricultural catchment area were investigated in the present study. The ditch was classified as highly influenced by surface water runoff. This classification is based on a biological indicator system (LIESS 1992, LIESS 1993) and measurements of surface water runoff. Abundance, drift, and emergence of three macroinvertebrate species were recorded for one year (1992) to obtain information on causal connections regarding population dynamic and surface water runoff.
During one runoff event in March 1992 two important members of the community, namely Gammarus pulex (Crustacea: Amphipoda) and Stenophylax permistus (Trichoptera: Limnephilidae) showed a drift rate ten times higher than the normal values. Due to this drift peak the abundance of G. pulex was reduced (p=0.098; t=1.743: df=18). During the following six months the population density of this species increased again as a result of upstream movement and reproduction. In contrast, the population density of S. permistus was significantly reduced (p=0.012; t=2.791; df=18) during the runoff event. In addition, recolonisation could not be observed in 1992. Another caddis fly species (Limnephilus lunatus) showed an extremely shortened period of emergence compared to its emergence in ditches with low surface water runoff. The emergence of nearly all pupae was induced by a single runoff event in July 1992. This led us to conclude that short-term surface water runoff influences the population dynamic, and hence the composition of the macroinvertebrate community in running waters. Therefore, an evaluation of surface water runoff is an essential component of an ecological assessment regarding the agricultural impact on running water ecosystems.
• Endogenous metabolome was significantly affected even at very low pesticide exposure. • Interac... more • Endogenous metabolome was significantly affected even at very low pesticide exposure. • Interaction between food stress and pesticides incurred stronger metabolic alterations. • Metabolomic changes increased over seven days after contamination.
Ökotoxikologie: Ökosystemare Ansätze und Methoden, 1999
This study, based on two examples, demonstrates that intraspecific stress between individuals of ... more This study, based on two examples, demonstrates that intraspecific stress between individuals of one species alters the sigmoid concentration-response relation-ships. A high intraspecific stress due to high population density can reduce the survival in the control. However, stress due to xenobiotica is reducing the intraspecific stress. As a consequence, test systems with high intra-specific stress are less sensitive to xenobiotic stress than systems with low intraspecific stress. According to the tests conditions, the NOEC can differ of some orders of magnitude and the concentration-response curve shows a modified slope. It is, thus, important to consider the degree of intraspecific interaction in the design and interpretation of test-systems as this can partly compensate the effects of xenobiotica. Since intraspecific stress is an integral property of natural populations, it is expected that they react less to xenobiotica than test-systems with low intra-specific interaction.
Global pesticide exposure in agriculture leads to biodiversity loss, even at ultra-low concentrat... more Global pesticide exposure in agriculture leads to biodiversity loss, even at ultra-low concentrations below the legal limits. The mechanisms by which the effects of toxicants act at such low concentrations are still unclear, particularly in relation to their propagation across the different biological levels. In this study, we demonstrate, for the first time, a cascade of effects from the gene to the community level. At the gene level, agricultural pesticide exposure resulted in reduced genetic diversity of field-collected Gammarus pulex, a dominant freshwater crustacean in Europe. Additionally, we identified alleles associated with adaptations to pesticide contamination. At the individual level, this genetic adaptation to pesticides was linked to a lower fecundity, indicating related fitness costs. At the community level, the combined effect of pesticides and competitors caused a decline in the overall number and abundance of pesticides susceptible macroinvertebrate competing with gammarids. The resulting reduction in interspecific competition provided an advantage for pesticide-adapted G. pulex to dominate macroinvertebrate communities in contaminated areas, despite their reduced fitness due to adaptation. These processes demonstrate the complex cascade of effects, and also illustrate the resilience and adaptability of biological systems across organisational levels to meet the challenges of a changing environment.
Short pulses of toxicants can cause latent effects that occur long after the contamination event ... more Short pulses of toxicants can cause latent effects that occur long after the contamination event and are currently unpredictable. Here, we introduce an analytical framework for mechanistically predicting latent effects considering interactive effects of multiple stressors and hormetic effect compensation. We conducted an extensive investigation using high temporal resolution microcosm data of the mayfly Cloeon dipterum exposed to the pyrethroid pesticide esfenvalerate for 1 h. For 6 pesticide concentrations and 3 food levels we identified daily general stress information and predicted their synergistic interactions using the Stress Addition Model (SAM). Our analysis revealed that, especially at low concentrations, latent effects contributed most to the overall effect. At low concentrations ranging from 1/100 to 1/10,000 of the acute LC50 , resulting in a 30–15 % mortality, latent effects prevailed, accounting for 92 % to 100 % of the observed effects. Notably, the concentration causing 15 % mortality 29 days post-exposure was 1000 times lower than the concentration causing the same mortality 4 days post-exposure, emphasizing the time-dependent nature of this Latent-Effect-Amplification (LEA). We identified both acute mortality and latent effects of pesticides on emergence. Furthermore, we observed pesticide-induced compensation mechanisms at both individual and population levels, transforming the initial monotonic concentration-response relationship into a hormetic, tri-phasic response pattern. Combining these processes enabled a quantification of the underlying causes of latent effects. Our findings highlight that short-term pesticide exposures can lead to latent effects of particular significance, especially at low effect concentrations.
Monitoring for pesticides in surface waters can be problematic. These substances are generally di... more Monitoring for pesticides in surface waters can be problematic. These substances are generally diffuse and transient pollutants and are often present at low concentrations. Difficulties in monitoring for pesticides makes attributing any observed changes in a biological community to pesticide contamination complicated. An indicator that would allow us to diagnose pesticide contamination at a site would be very useful.
A review of current biological indicators shows the SPEAR approach to be one of the most promising bioindicator methods to detect pesticide contamination in lotic ecosystems (Schriever et al. 2008). The SPEAR approach has been used to show a link between levels of insecticide and fungicide exposure and stream macroinvertebrate community structure. As the SPEAR approach is based on species traits it is not restricted to use in one geographic area, and it has been successfully applied in different biogeographical regions in Europe. It was therefore proposed that the pesticide-specific SPEAR indicator should be revised for use in England and Wales for possible inclusion in routine Environment Agency monitoring.
The SPEAR concept is currently the only trait-based approach to identify species vulnerable to pesticide contamination. The approach is based on species sensitivity to organic toxicants and life-cycle traits responsible for potential exposure and recovery (generation time, migration ability, presence of aquatic stages during maximum pesticide exposure), and classifies the species into “species at risk” and “species not at risk” according to these traits. The existing SPEAR indicator is based on information on macroinvertebrates from mainland Europe. Although this may be directly applicable in the UK, adaptation and revision was desirable for a more efficient application of the method in this geographical region. In particular, the trait database required some limited revision and updating with UK species and ecological information from this region.
The existing SPEAR indicator is based on species-level data. Much of the macroinvertebrate data collected by the Environment Agency is at a family level. It was therefore necessary to develop a family-level SPEAR indicator and to establish whether the family-level tool remained sensitive enough to indicate pesticide exposure.
In summary, the aim of this study was to revise and update the SPEAR database for use in the UK and to compare the SPEAR indices based on species and family levels of taxonomic identification using data sets for other European regions (Finland, France, and Germany).
Revision of the database resulted in addition of 38 new taxa. For 125 taxa, UK-specific ecological information was included in the database as separate region-specific entries. For 54 taxa information on ecological traits was corrected, but not defined as UKspecific. Sixty-six out of all 152 families in the database were defined as families at risk for UK conditions. The updated database (Liess et al. 2008) now contains most of the UK stream macroinvertebrate taxa together with information about their respective ecological traits.
Statistical comparison of the SPEAR indexes based on family and species levels of taxonomic resolution has shown that the family-level index can be effectively used to detect pesticide contamination in streams. The effect of upstream recovery areas and levels of seasonal variability were similar for both the family and species level indexes. The predictive power of the family-level index is expected to be only slightly lower than that of the species-level index. Taking into account the time-consuming nature, cost and difficulties of species-level identification, the family-level index is a promising and cost-effective bioindicator tool for detecting pesticide contamination in streams. Future application of the SPEAR approach in the UK requires validation in field investigations. A field survey programme, including assessment of exposure and effect, should be performed to validate the SPEAR approach for UK conditions.
The agricultural use of pesticides leads to environmentally relevant pesticide concentrations tha... more The agricultural use of pesticides leads to environmentally relevant pesticide concentrations that cause adverse effects on stream ecosystems. These effects on invertebrate community composition can be identified by the bio-indicator SPEARpesticides. However, refuge areas have been found to partly confound the indicator. On the basis of three monitoring campaigns of 41 sites in Central Germany, we identified 11 refuge taxa. The refuge taxa, mainly characterized by dispersal-based resilience, were observed only nearby uncontaminated stream sec- tions and independent of the level of pesticide pressure. Through incorporation of this information into the re- vised SPEARpesticides indicator, the community structure specifically identified the toxic pressure and no longer depended on the presence of refuge areas. With regard to ecosystem functions, leaf litter degradation was pre- dicted by the revised SPEARpesticides and the median water temperature at a site (R2 = 0.38, P = 0.003). Further- more, we designed the bio-indicator SPEARrefuge to quantify the magnitude of general recolonization at a given stream site. We conclude that the taxonomic composition of aquatic invertebrate communities enables a specific indication of anthropogenic stressors and resilience of ecosystems.
Pesticide applications in agricultural crops often comprise a mixture of plant protection product... more Pesticide applications in agricultural crops often comprise a mixture of plant protection products (PPP), and single fields face multiple applications per year leading to complex pesticide mixtures in the environment. Restricted to single PPP, the current European Union PPP regulation, however, disregards the ecological risks of pesticide mixtures. To quantify this additional risk, we evaluated the contribution of single pesticide active ingredients to the additive mixture risk for aquatic risk indicators (invertebrates and algae) in 464 different PPP used, 3446 applications sprayed and 830 water samples collected in Central Europe, Germany. We identified an average number of 1.3 different pesticides in a single PPP, 3.1 for complete applications often involving multiple PPP and 30 in stream water samples. Under realistic worst-case conditions, the estimated stream water pesticide risk based on additive effects was 3.2 times higher than predicted from single PPP. We found that in streams, however, the majority of regulatory threshold exceedances was caused by single pesticides alone (69% for algae, 81% for invertebrates). Both in PPP applications and in stream samples, pesticide exposure occurred in repeated pulses each driven by one to few alternating pesticides. The time intervals between pulses were shorter than the
Under global change scenarios, multistress conditions may occur regularly and require adaptation.... more Under global change scenarios, multistress conditions may occur regularly and require adaptation. However, the adaptation to one stressor might be associated with the increased sensitivity to another stressor. Here, we investigated the ecological consequences of such trade-off under multiple stress. We compared the pesticide tolerance of the crustacean Gammarus pulex from agricultural streams with populations from reference streams. Under optimum temperature, G. pulex from agricultural streams were considerably more tolerant to pesticides as compared to the reference populations. Here, we assume that the increased tolerance in agricultural populations is the combination of acclimation, epigenetic effect, and genetic evolution. After experimental pre-exposure to very low concentration (LC 50 / 1000), reference populations showed increased pesticide tolerance. In contrast, pre-exposure did not further increase the tolerance of agricultural populations. Moreover, these populations were more sensitive to elevated temperature alone due to the hypothesized fitness cost of genetic adaptation to pesticides. However, both reference and agricultural populations showed a similar tolerance to the combined stress of pesticides and warming due to stronger synergistic effects in adapted populations. As a result, pesticide adaptation loses its advantage. The combined effect was predicted well using the stress addition model, developed for predicting the synergistic interaction of independent stressors. We conclude that under multistress conditions, adaptation to pesticides reduces the general stress capacity of individuals and trade-off processes increase the sensitivity to additional stressors. This causes strong synergistic effects of additional stressors on pesticide-adapted individuals.
Background: Pesticides are washed from agricultural fields into adjacent streams, where even shor... more Background: Pesticides are washed from agricultural fields into adjacent streams, where even short-term exposure causes long-term ecological damage. Detecting pesticide pollution in streams thus requires the expensive monitoring of peak concentrations during runoff events. Alternatively, exposure and ecological effects can be assessed using the SPEAR pesticides bioindicator that quantifies pesticide-related changes in the macroinvertebrate community composition. SPEAR pesticides has been developed in Central Europe and validated in other parts of Europe, Australia and South America; here we investigated its performance in East African streams. Results: With minimal adaptations of the SPEAR pesticdes index, we successfully characterized pesticide pollution in 13 streams located in Western Kenya. The East African SPEAR pesticides index correlated well with the overall toxicity of 30 pesticides (maximum toxic unit = maximum environmental vs. median lethal concentration) measured in stream water (R 2 = 0.53). Similarly, the SPEAR pesticides index correlated with the risk of surface runoff from agricultural fields (as identified based on ground slope in the catchment area and the width of protective riparian strips, R 2 = 0.45). Unlike other bioindicators designed to indicate general water pollution, SPEAR pesticides was independent of organic pollution and highly specific to pesticides. In 23% of the streams, pesticides exceeded concentrations considered environmentally safe based on European first tiered risk assessment. Conclusions: Increasing contamination was associated with considerable changes in the macroinvertebrate community composition. We conclude that pesticides need to be better regulated also in developing countries. SPEAR pesticides provides a straightforward and cost-efficient tool for the required monitoring of pesticide exposure in small to medium streams.
Ecological effects Recovery stream sections. These factors proved to be stronger predictors for t... more Ecological effects Recovery stream sections. These factors proved to be stronger predictors for the recovery than the pesticide tolerance. We revealed that the biological indicators SPEARpesticides and share of Ephemeroptera, Plecoptera and Trichoptera (EPT) are not suitable for the identification of such extreme events, when nearly all taxa are eradicated. Both indicators are functioning only when repeated stressors initiate long-term competitive replacement of sensitive by insensitive taxa. We conclude that pesticide spills can have significant long-term effects on stream macroinvertebrate communities. Regular ecological monitoring is imperative to identify such ecosystem impairments, combined with analytical chemistry methods to identify the potential sources of spills.
Background: The European environmental risk assessment of plant protection products considers aqu... more Background: The European environmental risk assessment of plant protection products considers aquatic model ecosystem studies (microcosms/mesocosms, M/M) as suitable higher tier approach to assess treatment-related effects and to derive regulatory acceptable concentrations (RAC). However, it is under debate to what extent these artificial test systems reflect the risks of pesticidal substances with potential harmful effects on natural macroinvertebrate communities, and whether the field communities are adequately protected by the results of the M/M studies. We therefore compared the composition, sensitivity and vulnerability of benthic macroinvertebrates established in control (untreated) groups of 47 selected M/M studies with natural stream communities at 26 reference field sites. Results: Since 2013 the number of benthic macroinvertebrate taxa present in M/M studies has increased by 39% to a mean of 38 families per study. However, there is only an average of 4 families per study that comply with the recommendations provided by EFSA (EFSA J 11:3290, 2013), i.e.: (i) allowing statistical identification of treatmentrelated effects of at least 70% according to the minimum detectable difference (here criteria are slightly modified) and (ii) belonging to insects or crustaceans (potentially sensitive taxa for pesticidal substances). Applying the criterion of physiological sensitivity according to the SPEAR pesticides concept, the number of families decreases from 4 to 2.3 per study. Conclusions: Most taxa established in recent M/M studies do not suitably represent natural freshwater communities. First, because their abundances are often not sufficient for statistical detection of treatment-related effects in order to determine an appropriate endpoint and subsequent RAC. Recommendations are given to improve the detectability of such effects and their reliability. Second, the taxa often do not represent especially sensitive or vulnerable taxa in natural communities in terms of their traits. The uncertainties linked to vulnerable taxa in M/M studies are especially high considering their representativity for field assemblages and the comparability of factors determining their recovery time. Thus considering recovery for deriving a RAC (i.e., ERO-RAC) is not recommended. In addition, this paper discusses further concerns regarding M/M studies in a broader regulatory context and recommends the development of alternative assessment tools and a shift towards a new paradigm.
Following agricultural application, pesticides can enter streams through runoff during rain event... more Following agricultural application, pesticides can enter streams through runoff during rain events. However, little information is available on the temporal dynamics of pesticide toxicity during the main application period. We inves- tigated pesticide application and large scale in-stream monitoring data from 101 agricultural catchments obtained from a Germany-wide monitoring from April to July in 2018 and 2019. We analysed temporal patterns of pesticide application, in-stream toxicity and exceedances of regulatory acceptable concentrations (RAC) for over 70 pesticides. On a monthly scale from April to July, toxicity to invertebrates and algae/aquatic plants (algae) obtained with event- driven samples (EDS) was highest in May/June. The peak of toxicity towards invertebrates and algae coincided with the peaks of insecticide and herbicide application. Future monitoring, i.e. related to the Water Framework Directive, could be limited to time periods of highest pesticide applications on a seasonal scale. On a daily scale, toxicity to inver- tebrates from EDS exceeded those of grab samples collected within one day after rainfall by a factor of 3.7. Within two to three days, toxicity in grab samples declined compared to EDS by a factor of ten for invertebrates, and a factor of 1.6 for algae. Thus, toxicity to invertebrates declined rapidly within 1 day after a rainfall event, whereas toxicity to algae remained elevated for up to 4 days. For six pesticides, RAC exceedances could only be detected in EDS. The exceedances of RACs coincided with the peaks in pesticide application. Based on EDS, we estimated that pesticide ex- posure would need a 37-fold reduction of all analysed pesticides, to meet the German environmental target to keep RAC exceedances below 1 % of EDS. Overall, our study shows a high temporal variability of exposure on a monthly but also daily scale to individual pesticides that can be linked to their period of application and related rain events.
Aquatic communities are exposed to repeated pulses of toxicants and environmental stressors. We h... more Aquatic communities are exposed to repeated pulses of toxicants and environmental stressors. We hypothesize that the dose, order, and timing of stress events shape the interactions of these communities. For this, we conducted a fully-crossed, four-factorial, multiple stress exposure experiment to study the combined effects of Esfenvalerate and ultraviolet-B (UV-B) radiation related to the exposure timing and order on Daphnia magna. We revealed that initial exposure to low stress doses, independent of the stress type (UV-B or Esfenvalerate), significantly increased the resistance toward the second stressor. This beneficial effect was apparent only when the second stressor was applied immediately after the first stressor (p < 0.01). When the period between stressor applications was extended to 2 days, the antagonism between the two stressors turned into synergism. The stressor interaction could be predicted with an abstract-mechanistic model of the temporal dynamics of the early-stage stress response. With this model, the timing and order of exposures were able to successfully explain interactions observed in all treatments (model-R 2 = 1.0). We conclude that especially the duration of a break between exposures and the exposure dose has a decisive influence on interactions between toxicants and environmental stressors.
Vegetated buffer strips (VBS) are an effective measure to retain pesticide inputs during rain eve... more Vegetated buffer strips (VBS) are an effective measure to retain pesticide inputs during rain events. Numerous studies have examined the retention effects of VBS on pesticides. However, no study has addressed on a large scale with event-related peak concentrations how wide the VBS should be to avoid ecological impacts on aquatic life. Here, we investigated for 115 lowland stream sections in Germany the relevance of environmental and physico-chemical parameters to determine the instream pesticide concentration and their ecological risks. Based on peak concentrations related to rain events with precipitation amount resulting in VBS relevant surface runoff for 30 of the 115 investigated stream sections (25 to 70 mm/d), we demonstrated that the average width of VBS was the main parameter (R 2 = 0.38) reducing the pesticide input ratio, indicating a relevant proportion of surface runoff contributing to the total in-stream pesticide concentrations. Additionally, dry ditches within agricultural fields increased pesticide input (R 2 = 0.31). Generally, substances classified as slightly mobile were better retained by VBS than mobile substances. Other factors including slope, land use and vegetation cover of VBS had only a minor influence. We assessed the ecological risk of in-stream pesticide concentrations by quantifying exceedances of regulatory-(RAC) and field-validated acceptable concentrations (AC field). We then translated this ecological risk into protective VBS width by calculating the quotient of in-stream concentration and threshold (RQ). We estimate that a VBS width of 18 m is sufficient to meet the RQ ACfield protection goal for 95% of streams. The presence of dry ditches increased the protective VBS width to 32 m. In current agricultural practice, however, 26% of the water stretches investigated do not comply with the prescribed 5 m VBS. An extension of the VBS area to 18 m would demand 3.8% of agricultural land within the catchments. A 50% reduction in pesticide use, as required by the European green deal, would still result in 39% (RAC) and 68% (AC field) of event-related samples being exceeded. Consequently, we see the extension of the VBS width as the most efficient mearsure to sustainably reduce pesticide concentrations in small streams.
The Water Framework Directive (WFD) demands that good status is to be achieved for all European w... more The Water Framework Directive (WFD) demands that good status is to be achieved for all European water bodies. While governmental monitoring under the WFD mostly concludes a good status with regard to pesticide pollution, numerous scientific studies have demonstrated widespread negative ecological impacts of pesticide exposure in surface waters. To identify reasons for this discrepancy, we analysed pesticide concentrations measured in a monitoring campaign of 91 agricultural streams in 2018 and 2019 using methodologies that exceed the requirements of the WFD. This included a sampling strategy that takes into account the periodic occurrence of pesticides and a different analyte spectrum designed to reflect current pesticide use. We found that regulatory acceptable concentrations (RACs) were exceeded for 39 different pesticides at 81% of monitoring sites. In comparison, WFD-compliant monitoring of the same sites would have detected only eleven pesticides as exceeding the WFD-based environmental quality standards (EQS) at 35% of monitoring sites. We suggest three reasons for this underestimation of pesticide risk under the WFD-compliant monitoring: (1) The sampling approach - the timing and site selection are unable to adequately capture the periodic occurrence of pesticides and investigate surface waters particularly susceptible to pesticide risks; (2) the measuring method - a too narrow analyte spectrum (6% of pesticides currently approved in Germany) and insufficient analytical capacities result in risk drivers being overlooked; (3) the assessment method for measured concentrations - the protectivity and availability of regulatory thresholds are not sufficient to ensure a good ecological status. We therefore propose practical and legal refinements to improve the WFD’s monitoring and assessment strategy in order to gain a more realistic picture of pesticide surface water pollution. This will enable more rapid identification of risk drivers and suitable risk management measures to ultimately improve the status of European surface waters.
Biological indices aim to reflect the ecological quality of streams based on the community's spec... more Biological indices aim to reflect the ecological quality of streams based on the community's species or trait composition. Accordingly, the capability to predict the ecological quality depends on (i) the knowledge on the association of taxa or traits with stressors and (ii) the taxonomic and quantitative resolution of taxa. Generally speaking, a higher resolution is associated with a better linkage between environmental condition and biological response but also with higher efforts and costs. So far it is unknown how the taxonomic and quantitative resolution affect the ecological quality assessment of streams related to pesticide effects when applying the invertebrate-based indicator SPEARpesticides. We investigated the ecological quality of 101 streams considering four taxonomic levels (species, genus, family, order) and three quantitative resolutions (abundance, three abundance classes, and presence-absence). In a multiple linear regression analysis between 13 investigated stressors and SPEARpesticides, the full models' explained variance remained fairly constant with decreasing taxonomic and quantitative resolution. As expected, the highest association between pesticide pressure and SPEARpesticides was reached at a species/abundance resolution yielding an R2 of 0.43. In contrast, the lowest quantitative resolution of order level combined with presence-absence information revealed an explained variance of 0.28 R2. We suggest the family/abundance class resolution (R2 = 0.38) as the best trade-off between effort and accuracy for large-scale monitoring. Due to a comparable linear regression at family/abundance class resolution, the assigned ecological quality classes were largely congruent (69 %) to species/abundance resolution. We conclude that the ecological quality assessment with SPEARpesticides at family/abundance class resolution can be used to link pesticide contamination and invertebrate community structure with less taxonomic expertise and less quantification effort.
Bulletin of Environmental Contamination and Toxicology, 2001
The community inhabiting a body of water represents the "ecological memory" of the habitat, and h... more The community inhabiting a body of water represents the "ecological memory" of the habitat, and hence the composition of aquatic communities is used to monitor various stressors. A prerequisite for the development of useful indicator systems is that the species be ranked in order of their sensitivity to the stress parameter of interest. In the case of toxic xenobiotics, no existing classifications of aquatic macroinvertebrate species according to their specific sensitivities are sufficiently comprehensive to allow these organisms to be used as indicators for contamination of the water. However, this is precisely the area in which community-based indicator systems are particularly de-sirable. This is because precise information about contamination via chemical analysis of water samples is often difficult to obtain and laborious (Liess et al. 1999). Changes in aquatic communities, as a consequence of exposure to test substances, can be examined by contamination of experimental mesocosms. The results have repeatedly shown that, while various characteristics of the individual species tested are influential, the most important is the animal's specific physiological sensitivity to the contaminant in the acute toxicity test (Van den Brink et al. 1996; Sherratt et al. 1999). Therefore, the ranking of species should be based on the results of toxicity tests. For most species, however, hardly any information about their sensitivities is available (Notenboom et al 1995). Thus, what is required, is a comprehensive compilation of sensitivities at such a taxonomic level, that from known species sensitivities, inferences can be made about species not yet subjected to toxicity tests.
Results of environmental risk assessments based merely on toxic effects of contaminants at the in... more Results of environmental risk assessments based merely on toxic effects of contaminants at the individual level, without consideration of population-level effects, may be questionable. The aim of the present study was to investigate how limited food resources, resulting in intraspecific competition, could interact with the chronic effect of short-term contamination with the insecticide esfenvalerate. Larvae of the mayfly, Cloeon dipterum, were exposed to esfenvalerate (0.001-100 g/L) for 1 h and then transferred to indoor microcosms containing insecticide-free water, where they were maintained at various food levels until emergence. The results showed that short-term exposure to 10 or 100 g/L resulted in acute mortality. Chronic effects on survival occurred at concentrations up to three orders of magnitude lower than that causing the acute effect (0.01 g/L). Food limitation increased effects on organisms during medium-term observation (8-15 d), but assessment of long-term survival rates suggested that the chronic effects of low insecticide concentrations could be compensated for, at least regarding some endpoints. The authors assume that in limited-food conditions, lethal and sublethal effects reduced competition between individuals, resulting in significantly increased final survival.
The study aims to evaluate the impact of insecticides associated with rainfall-induced surface ru... more The study aims to evaluate the impact of insecticides associated with rainfall-induced surface runoff from arable land on macroinvertebrate populations. These effects of insecticides were distinguished from the hydraulic stress also associated with surface runoff. Transient increase in discharge and insecticide contamination (maximum 6 g/L parathion-ethyl in stream water, 302 g/L fenvalerate in suspended particulates) was observed in a headwater stream subsequent to surface runoff from arable land. In the aquatic macroinvertebrate community, eight of the eleven abundant species disappeared, and the remaining three were reduced significantly in abundance following the insecticide-contaminated runoff. Recovery within 6 months was observed for four species and recovery within 11 months for nine species. Two species remained at a low population density for over a year. The effects of insecticides were distinguished from other parameters, such as hydraulic stress associated with surface runoff, as well. The causal connection between insecticide contamination and biological response was established by eliminating increased hydraulic stress during surface runoff using in-parallel bypass microcosms containing the dominant species Gammarus pulex and Limnephilus lunatus. The mortality of these species was similar to that of the same species in the stream. Additional microcosms, disconnected from the stream during runoff events, served as a control. Thus, the toxic potential of the runoff water is considered to be responsible for the observed effect on the macroinvertebrates. It is concluded that agricultural insecticide input may alter the dynamics of macroinvertebrate communities in streams.
The ecological effects of surface water runoff on the macroinvertebrate community in a ditch with... more The ecological effects of surface water runoff on the macroinvertebrate community in a ditch with an agricultural catchment area were investigated in the present study. The ditch was classified as highly influenced by surface water runoff. This classification is based on a biological indicator system (LIESS 1992, LIESS 1993) and measurements of surface water runoff. Abundance, drift, and emergence of three macroinvertebrate species were recorded for one year (1992) to obtain information on causal connections regarding population dynamic and surface water runoff.
During one runoff event in March 1992 two important members of the community, namely Gammarus pulex (Crustacea: Amphipoda) and Stenophylax permistus (Trichoptera: Limnephilidae) showed a drift rate ten times higher than the normal values. Due to this drift peak the abundance of G. pulex was reduced (p=0.098; t=1.743: df=18). During the following six months the population density of this species increased again as a result of upstream movement and reproduction. In contrast, the population density of S. permistus was significantly reduced (p=0.012; t=2.791; df=18) during the runoff event. In addition, recolonisation could not be observed in 1992. Another caddis fly species (Limnephilus lunatus) showed an extremely shortened period of emergence compared to its emergence in ditches with low surface water runoff. The emergence of nearly all pupae was induced by a single runoff event in July 1992. This led us to conclude that short-term surface water runoff influences the population dynamic, and hence the composition of the macroinvertebrate community in running waters. Therefore, an evaluation of surface water runoff is an essential component of an ecological assessment regarding the agricultural impact on running water ecosystems.
• Endogenous metabolome was significantly affected even at very low pesticide exposure. • Interac... more • Endogenous metabolome was significantly affected even at very low pesticide exposure. • Interaction between food stress and pesticides incurred stronger metabolic alterations. • Metabolomic changes increased over seven days after contamination.
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Papers by Matthias Liess
A review of current biological indicators shows the SPEAR approach to be one of the most promising bioindicator methods to detect pesticide contamination in lotic ecosystems (Schriever et al. 2008). The SPEAR approach has been used to show a link between levels of insecticide and fungicide exposure and stream macroinvertebrate community structure. As the SPEAR approach is based on species traits it is not restricted to use in one geographic area, and it has been successfully applied in different biogeographical regions in Europe. It was therefore proposed that the pesticide-specific SPEAR indicator should be revised for use in England and Wales for possible inclusion in routine Environment Agency monitoring.
The SPEAR concept is currently the only trait-based approach to identify species vulnerable to pesticide contamination. The approach is based on species sensitivity to organic toxicants and life-cycle traits responsible for potential exposure and recovery (generation time, migration ability, presence of aquatic stages during maximum pesticide exposure), and classifies the species into “species at risk” and “species not at risk” according to these traits. The existing SPEAR indicator is based on information on macroinvertebrates from mainland Europe. Although this may be directly applicable in the UK, adaptation and revision was desirable for a more efficient application of the method in this geographical region. In particular, the trait database required some limited revision and updating with UK species and ecological information from this region.
The existing SPEAR indicator is based on species-level data. Much of the macroinvertebrate data collected by the Environment Agency is at a family level. It was therefore necessary to develop a family-level SPEAR indicator and to establish whether the family-level tool remained sensitive enough to indicate pesticide exposure.
In summary, the aim of this study was to revise and update the SPEAR database for use in the UK and to compare the SPEAR indices based on species and family levels of taxonomic identification using data sets for other European regions (Finland, France, and Germany).
Revision of the database resulted in addition of 38 new taxa. For 125 taxa, UK-specific ecological information was included in the database as separate region-specific entries. For 54 taxa information on ecological traits was corrected, but not defined as UKspecific. Sixty-six out of all 152 families in the database were defined as families at risk for UK conditions. The updated database (Liess et al. 2008) now contains most of the UK stream macroinvertebrate taxa together with information about their respective ecological traits.
Statistical comparison of the SPEAR indexes based on family and species levels of taxonomic resolution has shown that the family-level index can be effectively used to detect pesticide contamination in streams. The effect of upstream recovery areas and levels of seasonal variability were similar for both the family and species level indexes. The predictive power of the family-level index is expected to be only slightly lower than that of the species-level index. Taking into account the time-consuming nature, cost and difficulties of species-level identification, the family-level index is a promising and cost-effective bioindicator tool for detecting pesticide contamination in streams. Future application of the SPEAR approach in the UK requires validation in field investigations. A field survey programme, including assessment of exposure and effect, should be performed to validate the SPEAR approach for UK conditions.
1995). Thus, what is required, is a comprehensive compilation of sensitivities at such a taxonomic level, that from known species sensitivities, inferences can be made about species not yet subjected to toxicity tests.
During one runoff event in March 1992 two important members of the community, namely Gammarus pulex (Crustacea: Amphipoda) and Stenophylax permistus (Trichoptera: Limnephilidae) showed a drift rate ten times higher than the normal values. Due to this drift peak the abundance of G. pulex was reduced (p=0.098; t=1.743: df=18). During the following six months the population density of this species increased again as a result of upstream movement and reproduction.
In contrast, the population density of S. permistus was significantly reduced (p=0.012; t=2.791; df=18) during the runoff event. In addition, recolonisation could not be observed in 1992. Another caddis fly species (Limnephilus lunatus) showed an extremely shortened period of emergence compared to its emergence in ditches with low surface water runoff. The emergence of nearly all pupae was induced by a single runoff event in July 1992. This led us to conclude that short-term surface water runoff influences the population dynamic, and hence the composition of the macroinvertebrate community in running waters. Therefore, an evaluation of surface water runoff is an essential component of an ecological assessment regarding the agricultural impact on running water ecosystems.
A review of current biological indicators shows the SPEAR approach to be one of the most promising bioindicator methods to detect pesticide contamination in lotic ecosystems (Schriever et al. 2008). The SPEAR approach has been used to show a link between levels of insecticide and fungicide exposure and stream macroinvertebrate community structure. As the SPEAR approach is based on species traits it is not restricted to use in one geographic area, and it has been successfully applied in different biogeographical regions in Europe. It was therefore proposed that the pesticide-specific SPEAR indicator should be revised for use in England and Wales for possible inclusion in routine Environment Agency monitoring.
The SPEAR concept is currently the only trait-based approach to identify species vulnerable to pesticide contamination. The approach is based on species sensitivity to organic toxicants and life-cycle traits responsible for potential exposure and recovery (generation time, migration ability, presence of aquatic stages during maximum pesticide exposure), and classifies the species into “species at risk” and “species not at risk” according to these traits. The existing SPEAR indicator is based on information on macroinvertebrates from mainland Europe. Although this may be directly applicable in the UK, adaptation and revision was desirable for a more efficient application of the method in this geographical region. In particular, the trait database required some limited revision and updating with UK species and ecological information from this region.
The existing SPEAR indicator is based on species-level data. Much of the macroinvertebrate data collected by the Environment Agency is at a family level. It was therefore necessary to develop a family-level SPEAR indicator and to establish whether the family-level tool remained sensitive enough to indicate pesticide exposure.
In summary, the aim of this study was to revise and update the SPEAR database for use in the UK and to compare the SPEAR indices based on species and family levels of taxonomic identification using data sets for other European regions (Finland, France, and Germany).
Revision of the database resulted in addition of 38 new taxa. For 125 taxa, UK-specific ecological information was included in the database as separate region-specific entries. For 54 taxa information on ecological traits was corrected, but not defined as UKspecific. Sixty-six out of all 152 families in the database were defined as families at risk for UK conditions. The updated database (Liess et al. 2008) now contains most of the UK stream macroinvertebrate taxa together with information about their respective ecological traits.
Statistical comparison of the SPEAR indexes based on family and species levels of taxonomic resolution has shown that the family-level index can be effectively used to detect pesticide contamination in streams. The effect of upstream recovery areas and levels of seasonal variability were similar for both the family and species level indexes. The predictive power of the family-level index is expected to be only slightly lower than that of the species-level index. Taking into account the time-consuming nature, cost and difficulties of species-level identification, the family-level index is a promising and cost-effective bioindicator tool for detecting pesticide contamination in streams. Future application of the SPEAR approach in the UK requires validation in field investigations. A field survey programme, including assessment of exposure and effect, should be performed to validate the SPEAR approach for UK conditions.
1995). Thus, what is required, is a comprehensive compilation of sensitivities at such a taxonomic level, that from known species sensitivities, inferences can be made about species not yet subjected to toxicity tests.
During one runoff event in March 1992 two important members of the community, namely Gammarus pulex (Crustacea: Amphipoda) and Stenophylax permistus (Trichoptera: Limnephilidae) showed a drift rate ten times higher than the normal values. Due to this drift peak the abundance of G. pulex was reduced (p=0.098; t=1.743: df=18). During the following six months the population density of this species increased again as a result of upstream movement and reproduction.
In contrast, the population density of S. permistus was significantly reduced (p=0.012; t=2.791; df=18) during the runoff event. In addition, recolonisation could not be observed in 1992. Another caddis fly species (Limnephilus lunatus) showed an extremely shortened period of emergence compared to its emergence in ditches with low surface water runoff. The emergence of nearly all pupae was induced by a single runoff event in July 1992. This led us to conclude that short-term surface water runoff influences the population dynamic, and hence the composition of the macroinvertebrate community in running waters. Therefore, an evaluation of surface water runoff is an essential component of an ecological assessment regarding the agricultural impact on running water ecosystems.