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The use of traits-based approaches and eco(toxico)logical models to advance the ecological risk assessment framework for chemicals
Abstract
This paper presents a framework to diagnose and predict the effects of chemicals, integrating two promising tools to incorporate more ecology into ecological risk assessment, viz. traits-based approaches and ecological modelling. Traits-based approaches are increasingly used to derive correlations between the occurrence of species traits and chemical exposure from biological and chemical monitoring data. This assessment can also be used in a diagnostic way, i.e. to identify the chemicals probably posing the highest risks to the aquatic ecosystems. The paper also describes how ecological models can be used to explore how traits govern the species-substance interactions and to predict effects at the individual, population and community/ecosystem level, i.e. from the receptor to the landscape level. This can be done by developing models describing the toxicokinetics and toxicodynamics of the chemical in the individual, the life-history of species and the connectivity of populations, determining their recovery and the food-web relations at the community/ecosystem level which determine the indirect effects. A special attention is given on how spatial aspects can be included into the ecological risk assessments using ecological models. The components of the framework are introduced and critically discussed. We describe how the different tools and data generated through experimentation (lab and semi-field) and biomonitoring can be integrated. The paper uses examples from the aquatic compartment, but the concepts that are used, and their integration within the framework can be generalised to other environmental compartments. Integr Environ Assess Manag © 2013 SETAC.
... The paths recorded under different experimental conditions were further analysed for deviances with a correlated random walk (CRW) model following the steps laid out in Turchin (1998). This type of model is suitable for evaluating paths in homogeneous environments and can be used to estimate the population dispersal rate within the respective substrate (Turchin 1998). ...
... The paths recorded under different experimental conditions were further analysed for deviances with a correlated random walk (CRW) model following the steps laid out in Turchin (1998). This type of model is suitable for evaluating paths in homogeneous environments and can be used to estimate the population dispersal rate within the respective substrate (Turchin 1998). For an analysis of movement paths according to the CRW model framework, a series of statistical approaches needs to be applied to test whether model assumptions are met. ...
... This can be checked visually via the frequency distribution of observed turning angles. CRW models furthermore assume that step lengths and turning angles within a path are not serially correlated (Turchin 1998). Such correlations can influence the model output and need to be interpreted accordingly (Turchin 1998;Westerberg et al. 2008;Dray et al. 2010). ...
Behaviour links physiological function with ecological processes and can be very sensitive towards environmental stimuli and chemical exposure. As such, behavioural indicators of toxicity are well suited for assessing impacts of pesticides at sublethal concentrations found in the environment. Recent developments in video-tracking technologies offer the possibility of quantifying behavioural patterns, particularly locomotion, which in general has not been studied and understood very well for aquatic macroinvertebrates to date. In this study, we aim to determine the potential effects of exposure to two neurotoxic pesticides with different modes of action at different concentrations (chlorpyrifos and imidacloprid) on the locomotion behaviour of the water louse Asellus aquaticus. We compare the effects of the different exposure regimes on the behaviour of Asellus with the effects that the presence of food and shelter exhibit to estimate the ecological relevance of behavioural changes. We found that sublethal pesticide exposure reduced dispersal distances compared to controls, whereby exposure to chlorpyrifos affected not only animal activity but also step lengths while imidacloprid only slightly affected step lengths. The presence of natural cues such as food or shelter induced only minor changes in behaviour, which hardly translated to changes in dispersal potential. These findings illustrate that behaviour can serve as a sensitive endpoint in toxicity assessments. However, under natural conditions, depending on the exposure concentration, the actual impacts might be outweighed by environmental conditions that an organism is subjected to. It is, therefore, of importance that the assessment of toxicity on behaviour is done under relevant environmental conditions.
... These characteristics make assessment and prediction of risks from multiple stressors to ecological processes and entities difficult. With recent advances in key areas such as ecological modelling, biomonitoring science, ecogenomics and earth-observation technologies, significant new opportunities for the study of complex stress regimes are now available (Vörösmarty et al. 2010;Burton et al. 2012;Baird and Hajibabaei 2012;Van den Brink et al. 2013). So as to assess how emerging science and new tools can be applied to study multiple stressors at a large (ecosystem) scale and to facilitate greater integration of approaches among different scientific disciplines, a workshop was organised 10-12 September 2014 at the Sydney Institute of Marine Sciences, Sydney, Australia . ...
... The holy grail of ecological risk assessment is the understanding of the effects of multiple stressors on individuals, populations, and, ultimately, groups of interacting species at different spatial scales (De Laender and Janssen 2013; Van den Brink et al. 2013). Understanding interactions among stressors requires manipulative (field) experiments and field surveys spanning wide gradients of focal stressors. ...
... Lange et al. (2014) successfully used biological traits of stream invertebrates to disentangle the effects of multiple stressors in an agricultural catchment. These examples also showed that both laboratory and field data can be used for this purpose (Van den Brink et al. 2013). ...
So as to assess how emerging science and new tools can be applied to study multiple stressors at a large (ecosystem) scale and to facilitate greater integration of approaches among different scientific disciplines, a workshop was organised on 10-12 September 2014 at the Sydney Institute of Marine Sciences, Sydney, Australia. The present paper discusses the limitations of the current risk-assessment approaches and how multiple stressors at large scales can be better evaluated in ecological risk assessments to inform the development of more efficient and preventive management policies based on adaptive management in the future. A future risk-assessment paradigm that overcomes these limitations is presented. This paradigm includes cultural and ecological protection goals, the development of ecological scenarios, the establishment of the relevant interactions among species, potential sources of stressors, their interactions and the development of cause-effect models. It is envisaged that this will be achievable through a greater integration of approaches among different scientific disciplines and through the application of new and emerging tools such as 'big data', ecological modelling and the incorporation of ecosystem service endpoints.
... These characteristics make assessment and prediction of risks from multiple stressors to ecological processes and entities difficult. With recent advances in key areas such as ecological modelling, biomonitoring science, ecogenomics and earth-observation technologies, significant new opportunities for the study of complex stress regimes are now available (Vörösmarty et al. 2010;Burton et al. 2012;Baird and Hajibabaei 2012;Van den Brink et al. 2013). So as to assess how emerging science and new tools can be applied to study multiple stressors at a large (ecosystem) scale and to facilitate greater integration of approaches among different scientific disciplines, a workshop was organised 10-12 September 2014 at the Sydney Institute of Marine Sciences, Sydney, Australia . ...
... The holy grail of ecological risk assessment is the understanding of the effects of multiple stressors on individuals, populations, and, ultimately, groups of interacting species at different spatial scales (De Laender and Janssen 2013; Van den Brink et al. 2013). Understanding interactions among stressors requires manipulative (field) experiments and field surveys spanning wide gradients of focal stressors. ...
... Lange et al. (2014) successfully used biological traits of stream invertebrates to disentangle the effects of multiple stressors in an agricultural catchment. These examples also showed that both laboratory and field data can be used for this purpose (Van den Brink et al. 2013). ...
This poster presentation discussed the limitations of the current assessment approaches and how multiple stressors at large scales can be better evaluated in ecological risk assessments to inform the development of more efficient and preventive management policies based on adaptive management in the future. It is envisaged that the integration of new and emerging tools such as 'Big Data', ecological modelling with a future risk assessment paradigm will make this achievable.
... Taken individually, both the taxonomy-and the trait-based biomonitoring provide partial information about an ecosystem [13], while the combination of the two approaches better describes the ecosystem status as well as the ability to predict changes in key ecosystem processes under variable environmental conditions (e.g., [10,14]). Integrated approaches allow to "incorporate more ecology into ecological risk assessment" [15]. Trait-based approaches deepen the environmental risk assessment, offering information on multiple aspects such as life-history and food web relations (e.g., [16]). ...
... Schmid-Araya et al. [45] suggested that studies on the variation of biomass as a function of the temperature of lakes (but also of other aquatic ecosystems) should be considered a priority in the current context of climate change. Studying meiofaunal traits under climate change impact is of pivotal importance in order to understand the way by which climate-changing environments alter the functioning and the structures of freshwater ecosystems [2], especially in the littoral zone of lakes that is exposed to high variability of the abiotic parameters [15]. For instance, Jeppesssen et al. [61] argue that a change in the meiobenthic community structure of lakes is expected as a response to drought periods. ...
We carried out an overview of the studies on the traits of the meiofauna of the littoral zone of lakes to investigate the question relating to the Raunkiaeran shortfall (lack of knowledge on biological traits). For this purpose, we selected a series of keywords associated with response and effect traits (feeding habits, locomotion and substrate relation, body size, shape and mass, life history, reproductive strategy, respiration and thermal tolerance) and we counted the relative frequency of occurrence in a set of scientific papers retrieved from Web of Science. The results showed that, except for the traits related to diet and feeding habits, the Raunkiaeran shortfall is very pronounced for all meiofaunal taxa of the littoral zone of lakes, especially for those related to soft-bodied organisms. The reason behind this deficiency concerns many aspects ranging from the high taxonomic expertise required to the intrinsic difficulties of observing organisms of such a small size. The relationship with temperature has not been sufficiently explored and formalized in any of the examined traits; this research aspect needs to be rapidly addressed since the prospects of climate change impacts on lake littorals are expected to be particularly severe.
... Mechanistic effects models, including organism-level, population-level, and multispecies models (i.e., food web and ecosystem models) may provide great insight into and important predictions of indirect effects [86]. Various models have been developed, many as an aid to ecological risk assessment, and they may be used individually or in concert to extrapolate the impacts of chemicals across levels of biological organization and spatial scales [26,[112][113][114]. However, overall, relatively few mechanistic models have addressed higher levels of biological organization. ...
... Most research in ecotoxicology has been at the individual-effects level [117], and methods to improve toxicity models continue to be developed. For example, models based on species-level traits and bioenergetics have the potential to improve predictions of species-level responses to various chemicals [114,118], and databases associated with toxic effects that include traditional toxicological information and the results of toxicogenomic or other molecular methods that identify the mode of toxic action are being developed, in some instances with computational modeling [119,120]. Information on direct effects on individuals will improve population models that estimate safe exposure limits for species, representing an important starting place to predict indirect effects. ...
Indirect effects in ecotoxicology are defined as chemical- or pollutant-induced alterations in the density or behavior of sensitive species that have cascading effects on tolerant species in natural systems. As a result, species interaction networks (e.g., interactions associated with predation or competition) may be altered in such a way as to bring about large changes in populations and/or communities that may further cascade to disrupt ecosystem function and services. Field studies and experimental outcomes as well as models indicate that indirect effects are most likely to occur in communities in which the strength of interactions and the sensitivity to contaminants differ markedly among species, and that indirect effects will vary over space and time as species composition, trophic structure, and environmental factors vary. However, knowledge of indirect effects is essential to improve understanding of the potential for chemical harm in natural systems. For example, indirect effects may confound laboratory-based ecological risk assessment by enhancing, masking, or spuriously indicating the direct effect of chemical contaminants. Progress to better anticipate and interpret the significance of indirect effects will be made as monitoring programs and long-term ecological research are conducted that facilitate critical experimental field and mesocosm investigations, and as chemical transport and fate models, individual-based direct effects models, and ecosystem/food web models continue to be improved and become better integrated.
... This may be also applicable for predicting indirect effects of pesticides and other toxic chemicals on biological communities. Given that interspecific interactions can be characterized by ecological traits (e.g., food preference, habitat preference, and mode of feeding), such traits may play a key role in determining the direction and strength of indirect effects of pesticides through the interactions ( Van den Brink et al. 2013). However, since previous studies on the relationships between ecotoxicological impacts and species traits have been largely focused on the effects of direct toxicity, whether species traits are useful predictors of indirect pesticide effects is still an open question. ...
... Recently, some ecotoxicologists have attempted to unravel the relationships between susceptibility of species to pesticides in natural conditions and functional traits such as generation time and dispersal ability (Liess and von der Ohe 2005, Clements and Rohr 2009, Liess and Beketov 2011, Rubach et al. 2011). However, the role of species traits in determining the sign and strength of pesticides indirect effects is still poorly known ( Van den Brink et al. 2013). We suggest that focusing on traits that characterize biotic interactions between plants and animals would be useful not only for a better understanding of the mechanistic basis of indirect effects of pesticides and other toxicants but also for a realistic risk assessment of chemicals under real-world conditions. ...
Indirect effects of agrochemicals on organisms via biotic interactions are less studied than direct chemical toxicity despite their potential relevance in agricultural landscapes. In particular, the role of species traits in characterizing indirect effects of pesticides has been largely overlooked. Moreover, it is still unclear whether such indirect effects on organisms are prevalent even when the organisms are exposed to direct toxicity. We conducted a mesocosm experiment to examine indirect effects of an herbicide (pentoxazone) on aquatic predatory insects of rice paddies. Because the herbicide selectively controls photosynthetic organisms, we assumed that the effects of the herbicide on predatory insects would be indirect. We hypothesized that phytophilous predators such as some Odonata larvae, which cling to aquatic macrophytes, would be more subject to negative indirect effects of the herbicide through a decrease in abundance of aquatic macrophytes than benthic, nektonic, and neustonic predators. Also, we crossed‐applied an insecticide (fipronil) with herbicide application to examine whether the indirect effects of the herbicide on the assembling predators act additively with direct adverse effects of the insecticide. The herbicide application did not decrease the abundance of phytoplankton constitutively, and there were no clear negative impacts of the herbicide on zooplankton and prey insects (detritivores and herbivores). However, the abundance of aquatic macrophytes was significantly decreased by the herbicide application. Although indirect effects of the herbicide were not so strong on most predators, their magnitude and sign differed markedly among predator species. In particular, the abundance of phytophilous predators was more likely to decrease than that of benthic, nektonic, and neustonic predators when the herbicide was applied. However, these indirect effects of the herbicide could not be detected when the insecticide was also applied, seemingly due to fipronil's high lethal toxicity. Our study highlights the importance of species traits such as microhabitat use, which characterize biotic interactions, for predicting indirect effects of agrochemicals. Given that indirect effects of the chemicals vary in response to species traits and direct toxicity of other chemicals, efforts to explain this variation are needed to predict the realistic risks of indirect effects of agrochemicals in nature. This article is protected by copyright. All rights reserved.
... Toxicokinetics (TK) describes "what an individual does with the chemical", in the model it translates the external concentration into an internal concentration. The toxicodynamics (TD) describes "what a chemical does with the individual", in the model the TD links the internal concentration to the effect on the individual (Jager et al., 2011;Van den Brink et al., 2013). ...
... TKTD modelling can predict the outcome for different exposure profiles and therefore it is seen as a promising tool in ecological risk assessment (EFSA PPR Panel, 2018;Focks et al., 2018;Ashauer et al., 2013;Jager, 2014;Van den Brink et al., 2013). Jager et al. (2011) developed a unified TKTD framework called the General Unified Threshold model for Survival (GUTS), which was recently updated (Jager and Ashauer, 2018). ...
In the higher tiers of pesticide risk assessment, the Species Sensitivity Distribution (SSD)concept is often used to establish the effect threshold defined as the concentration protecting 95% of the species (Hazardous Concentration 5%, HC5). The toxicity data included in SSDs are normally established using a constant exposure regime. However, the exposure of pesticides in the field is often characterised by a variable exposure regime. Toxicokinetic-toxicodynamic (TKTD)models can be used to extrapolate the toxic effects of a chemical to a specific, time-variable exposure regime. The aim of this paper was to develop Exposure Pattern Specific SSDs (EPS-SSDs)for three insecticides using TKTD models and to compare the HC5 of different exposure patterns with the same time-weighted average concentration to evaluate whether the use of EPS-SSDs would change the outcome of the ecological risk assessment. The EPS-SSDs were developed by estimating TKTD parameters for the compounds chlorpyrifos, imidacloprid and lambda-cyhalothrin using results from standard, 96 h, single species tests. These parameter estimates were used for TKTD modelling to determine toxicity thresholds (e.g. LC10 and LC50)for contrasting exposure patterns after certain evaluation times (4, 10 or 100 days). HC5 values were constructed with TKTD-predicted LC10- and LC50- values for different exposure patterns characterised by similar time-weighted average concentrations. Differences between those HC5 values ranged from a factor 1 to a factor 2.3 for the short evaluation period (4 d). This difference was smaller when using an evaluation period of 10 days instead of 4 days and selecting the TKTD-predicted LC10 instead of TKTD-predicted LC50 based HC5s. For the long term evaluation period (100 d), a maximum difference of a factor of 30 was found.
... Therefore, the use of macroinvertebrate traits has been proposed as indicators of community effects due to specific stressors rather than applying a purely taxonomic approach [7]. Studies on organic contaminants [8,9], pesticides [10], salinity [11], and more recently metals [12,13] have shown the value of using biological traits in ecosystem assessment. ...
... Furthermore, the SPEAR salinity index did not show any significant response to other water quality parameters indicating its selectivity towards salinity [11]. Van den Brink et al. [7] also indicated that the SPEAR salinity indicator is a promising tool to use as an indicator of community or trait responses of macroinvertebrate river communities to salinity as a driver of change. In future, the SPEAR salinity approach should be tested more extensively for its effectiveness in South Africa as many systems here are already either experiencing salinization or at risk of future salinization. ...
Many biotic integrity indices are not able to isolate community effects due to pesticide exposure as the communities also respond to other anthropogenic and natural stressors. A macroinvertebrate trait bioindicator system that is pesticide specific was therefore developed to overcome these challenges. This system, called SPEAR (SPEcies At Risk), was applied in South Africa as an indicator to link known pesticide catchment usage to changes in the macroinvertebrate community, especially when analytical methods are inconclusive. In addition, the SPEAR salinity index within the SPEAR suite of tools was also evaluated for its effectiveness in South Africa. The results indicated that all of the sites have either been exposed to the same pesticide pressure or not been exposed to pesticides as the SPEAR results were similar when compared to the pesticide intensity. The interaction with other factors like nutrients or salinity was likely a factor that confounded the SPEAR pesticides indicator.
... The intrinsic sensitivity of species towards chemicals is often the most challenging of the four mentioned species traits that determine their vulnerability. In order to provide a mechanistic linkage between exposure and mortality probability, it was recently suggested to include an explicit description of the toxicokinetics and toxicodynamics (TK/TD) of effects into population models [33,34]. Especially in the light of time variable exposure situations such as is the case here (Fig. 1) this appears quite promising, because in such situations internal concentrations could increase up to considerable levels due to repeated applications, and in case of low Acc e p ted P r e p r i nt excretion rates lead to internal mixtures of compounds and the respective mixture effects. ...
... [26,[36][37][38]). In the future, the parameterisation of TK/TD models shall be eased by using correlations between physiological species traits and TK/TD parameters [34,39]. ...
... The intrinsic sensitivity of species towards chemicals is often the most challenging of the four mentioned species traits that determine their vulnerability. In order to provide a mechanistic linkage between exposure and mortality probability, it was recently suggested to include an explicit description of the toxicokinetics and toxicodynamics (TK/TD) of effects into population models [33,34]. Especially in the light of time variable exposure situations such as is the case here (Fig. 1) this appears quite promising, because in such situations internal concentrations could increase up to considerable levels due to repeated applications, and in case of low Acc e p ted P r e p r i nt excretion rates lead to internal mixtures of compounds and the respective mixture effects. ...
... [26,[36][37][38]). In the future, the parameterisation of TK/TD models shall be eased by using correlations between physiological species traits and TK/TD parameters [34,39]. ...
The aim of the conducted work was to assess whether populations effects and recovery times increase when a population of a vulnerable aquatic invertebrate is exposed to concentrations of one or multiple pesticides. The two sets of pesticide combinations are typical for orchard and tuber crops in The Netherlands. Exposure concentrations were predicted using the FOCUS step three modelling framework and the Dutch drainage ditch scenario. Recovery times were assessed using the MASTEP population model. We simulated the population dynamics and pesticide effects in a Monte Carlo style, by using EC50 values drawn from an arthropod species sensitivity distribution. In the tuber scenario, exposure to λ-cyhalothrin resulted in long-term effects, while exposure to the co-occurring compound fluazinam hardly resulted in (additional) effects. In the orchard scenario, three pesticides resulted in large effects just after exposure, but pulse exposures to these compounds did not coincide. Probabilities of effects for the single compounds added up for the combination, whereas the recovery times were not higher for the combination compared to those associated with exposure to the individual compounds. The conclusion from our simulations is that exposure to the evaluated pesticide packages may lead to increased mortality probabilities and effect sizes of the combination but does not lead to longer recovery times for populations with synchronized reproduction than when exposed to the individual compounds. Environ Toxicol Chem © 2013 SETAC.
... General predatory species like coccinellid beetles, carabid beetles, dragonfies, and damselfies reduced 20-50% following cartap hydrochloride application in rice ecosystems [43]. Impacts of agrochemicals including insecticides and herbicides on benefcial arthropods were poorly studied [44]. Furthermore, the abundance of phytophilous predators is more likely to decrease than that of benthic, nektonic, and neustonic predators when the agrochemical was applied because of high lethal toxicity especially fpronil [45]. ...
Rice (Oryza sativa) is one of the most important cereal crops with a diverse set of pests and natural enemies. Rice fields often support a high diversity of arthropods which contribute significantly to productivity. This diversity is frequently threatened due to indiscriminate applications of pesticides. Our aim was to emphasize on the predator diversity in agrochemical exposed rice field as well as on the impact of surrounding vegetation on beneficial insect diversity. Natural enemies’ data were recorded from randomly selected 10 quadrates by visual observation from each treatment. A total of 5,590 individuals of predators were observed during the study period which included 27 species belonging to 16 families from five orders of arthropods during the kharif season of rice. Statistically, there were no significant differences between the population of general natural enemies such as Odonata, Coleoptera, Hymenoptera, and Araneae in plots with insecticide and control during the different growth stages of rice cultivation. Diversity indices were almost similar in fields where pesticide was sprayed and not sprayed. Our study concluded that natural enemies are conserved by ensuring crop heterogeneity, growing insect-friendly plants (with high levels of nectar and pollen) as border crops, and judicious application of granule insecticide like cartap hydrochloride in a rice agro-ecosystem.
... However, species' ecological and ecophysiological traits, such as food chain origin, trophic position, and thermoregulatory strategy, may cause variation in the underlying ecological and contaminant variability when studying the trophic dynamics of contaminants, highlighting the need for trait-based modeling of contaminant dynamics. 3 Nonetheless, risk assessment modeling, typically using such TMFs and BMFs, does not commonly take into account such species traits nor their potential impact on modeling outcomes. ...
We investigated trophic dynamics of Hg in the polluted Baltic Archipelago Sea using established trophic magnification (TMFs) and biomagnification factors (BMFs) on a comprehensive set of bird, fish, and invertebrate species. As different ecological and ecophysiological species traits may affect trophic dynamics, we explored the effect of food chain (benthic, pelagic, benthopelagic) and thermoregulatory strategy on trophic total Hg (THg) dynamics, using different approaches to accommodate benthopelagic species and normalize for trophic position (TP). We observed TMFs and most BMFs greater than 1, indicating overall THg biomagnification. We found significantly higher pelagic TMFs (3.58-4.02) compared to benthic ones (2.11-2.34) when the homeotherm bird species were excluded from models, but not when included. This difference between the benthic and pelagic TMFs remained regardless of how the TP of benthopelagic species was modeled, or whether TMFs were normalized for TP or not. TP-corrected BMFs showed a larger range (0.44-508) compared to BMFs representing predator-prey concentration ratios (0.05-82.2). Overall, the present study shows the importance of including and evaluating the effect of ecological and ecophysiological traits when investigating trophic contaminant dynamics.
... Thus, functional trait-based approach is a promising tool to address plenty of ecological questions that contribute to biodiversity conservation (Castillo-Figueroa, 2018a; Jung & Threlfall, ISSN On-Line: 1807-0205 ISSN Printed: 0031-1049 ISNI: 0000-0004-0384-1825 2018). For example, several studies show that functional traits explain the impact of human-made landscapes on ecological groups of animals , the influence of climate change on species distributions and phenology (Robbirt et al., 2011), the effect of chemical elements on community assembly (Rubach et al., 2011;Van den Brink et al., 2013), and the distribution of functional diversity at macro-ecological scale (McGill et al., 2006;Hortal et al., 2015;González-Maya et al., 2017), to name a few examples. ...
New World bats are involved in key ecological processes and are good indicators of environmental changes. Recently, trait-based approaches have been used in several taxa to better understand mechanisms underlying species assemblages, biotic interactions, environmental relationships and ecosystem functions. However, despite the relevance of bats on ecosystem dynamics, so far, there is no conceptual framework that relies on the measurement of bat traits to address functional studies. Here, we present a set of 50 bat biological traits, which are suitable to assess environmental stressors and can potentially affect ecological processes. Several examples were provided to show the applicability of this framework in the study of Neotropical bat ecology. We suggest some considerations regarding trait-based approach including the importance of intraspecific variation, correlations between traits, response-effect framework, global dataset, and future directions to assess the reliability of functional relations across species and Neotropical regions by using traits. This could be helpful in tackling ecological questions associated with community assembly and habitat filtering, species diversity patterns along environmental gradients, and ecological processes. We envision this paper as a first step toward an integrative bat functional trait protocol held up with solid evidence.
... Exposure of the general population to these pesticide residues most commonly occurs through consumption of treated food sources or being in close contact to areas treated with pesticides. Pesticides residues contaminate soil and water, persist in crops, enter the food chain, and finally are ingested by humans through food and water [21][22]. Pesticide residues in food and crops are a result of direct application of pesticides to crops growing in the field, and to a lesser extent from pesticide residues remaining in the soil [23]. ...
... To provide comparable results among the different approaches, we defined identical initial (fully colonized) source habitat patches for habitat scenarios based on equal landscape scenarios and patch shares (Fig. 3). To decrease the variability and given our focus on landscape connectivity and related landscape variables, we further assigned a constant habitat quality (HQ = 0.625) to all habitat patches, though habitat quality likely varies in heterogeneous landscapes (Brink et al., 2013;Ye et al., 2013) and along streams. ...
... Chemically induced shifts in community composition are expected to correlate with chemical exposure and can, thus, be used as detectors. Additionally, considering species traits, i.e., biological characteristics relevant for the elucidation of chemical effects, rather than using the occurrence of different species, can help to increase diagnostic power or ecological information [66]. Therefore, an approach statistically separating chemical from non-chemical impacts on taxonomy or traits-based community composition was developed and tested in SOLUTIONS [56]. ...
Abstract Environmental water quality monitoring aims to provide the data required for safeguarding the environment against adverse biological effects from multiple chemical contamination arising from anthropogenic diffuse emissions and point sources. Here, we integrate the experience of the international EU-funded project SOLUTIONS to shift the focus of water monitoring from a few legacy chemicals to complex chemical mixtures, and to identify relevant drivers of toxic effects. Monitoring serves a range of purposes, from control of chemical and ecological status compliance to safeguarding specific water uses, such as drinking water abstraction. Various water sampling techniques, chemical target, suspect and non-target analyses as well as an array of in vitro, in vivo and in situ bioanalytical methods were advanced to improve monitoring of water contamination. Major improvements for broader applicability include tailored sampling techniques, screening and identification techniques for a broader and more diverse set of chemicals, higher detection sensitivity, standardized protocols for chemical, toxicological, and ecological assessments combined with systematic evidence evaluation techniques. No single method or combination of methods is able to meet all divergent monitoring purposes. Current monitoring approaches tend to emphasize either targeted exposure or effect detection. Here, we argue that, irrespective of the specific purpose, assessment of monitoring results would benefit substantially from obtaining and linking information on the occurrence of both chemicals and potentially adverse biological effects. In this paper, we specify the information required to: (1) identify relevant contaminants, (2) assess the impact of contamination in aquatic ecosystems, or (3) quantify cause–effect relationships between contaminants and adverse effects. Specific strategies to link chemical and bioanalytical information are outlined for each of these distinct goals. These strategies have been developed and explored using case studies in the Danube and Rhine river basins as well as for rivers of the Iberian Peninsula. Current water quality assessment suffers from biases resulting from differences in approaches and associated uncertainty analyses. While exposure approaches tend to ignore data gaps (i.e., missing contaminants), effect-based approaches penalize data gaps with increased uncertainty factors. This integrated work suggests systematic ways to deal with mixture exposures and combined effects in a more balanced way, and thus provides guidance for future tailored environmental monitoring.
... For this reason, some have argued that suborganismal metrics of energetic status may be powerful tools for predicting responses at organismal and population levels, which could then be incorporated in the ERA process (Ivanovici 1980;De Coen et al. 2000). Although DEB models and IBMs have recently been used for ERAs (Galic et al. 2010;Van den Brink et al. 2013), energetic endpoints measured at the organismal and suborganismal levels are not typically incorporated into ERAs because energetic metrics are rarely tethered to effects relevant to ERAs, such as survival, reproduction, and growth. Therefore, for energetic endpoints to inform ERA, a scientifically justifiable framework for mechanistically linking energetic effects to events of regulatory interest needs to be developed. ...
Adverse outcome pathways (AOPs) link toxicity across levels of biological organization, and thereby facilitate the development of suborganismal responses predictive of whole‐organism toxicity and provide the mechanistic information necessary for science‐based extrapolation to population‐level effects. Thus far AOPs have characterized various acute and chronic toxicity pathways; however, the potential for AOPs to explicitly characterize indirect, energy‐mediated effects from toxicants has yet to be fully explored. Indeed, although exposure to contaminants can alter an organism's energy budget, energetic endpoints are rarely incorporated into ecological risk assessment because there is not an integrative framework for linking energetic effects to organismal endpoints relevant to risk assessment (e.g., survival, reproduction, growth). In the present analysis, we developed a generalized bioenergetics‐AOP in an effort to make better use of energetic endpoints in risk assessment, specifically exposure scenarios that generate an energetic burden to organisms. To evaluate empirical support for a bioenergetics‐AOP, we analyzed published data for links between energetic endpoints across levels of biological organization. We found correlations between (1) cellular energy allocation and whole‐animal growth and (2) metabolic rate and scope for growth. Moreover, we reviewed literature linking energy availability to non‐traditional toxicological endpoints (e.g., locomotor performance), and found evidence for toxicants impairing aerobic performance and activity. We conclude by highlighting current knowledge gaps that should be addressed in order to develop specific bioenergetics‐AOPs. This article is protected by copyright. All rights reserved
... Mechanistic effect models include toxicokinetic-toxicodynamic models and AOPs that extrapolate chemical concentrations or molecular initiating events to individual-level effects (Ankley et al. 2010;Ashauer et al. 2011;Ashauer and Jager 2018), dynamic energy budget models that extrapolate changes in physiological responses to vital rates (Kooijman 2010), individual-based and population models that extrapolate individual-level effects to populationlevel consequences (Forbes et al. 2011;Martin et al. 2013), food web models that extrapolate effects on populations to community-level consequences (Pastorok et al. 2002), and ecological production functions that extrapolate from changes in biophysical structure or process to ecosystem functions driving ecosystem services (Bruins et al. 2017). Recent advances include the development of good modeling practice (Grimm et al. 2014); the integration of the toxicokinetic-toxicodynamic, dynamic energy budget, and individual-based model approaches (e.g., Gergs et al. 2016b); and the use of scenarios and trait-based approaches to improve the general applicability of models (Van den Brink et al. 2013;Rico et al. 2016). In addition to approaches for extrapolating across levels of biological organization, there are emerging computational approaches for extrapolating across species based on the conservation of key biological traits and molecular processes (e.g., LaLone et al. 2016;Ankley et al. 2016;question 6). ...
The United Nations' Sustainable Development Goals have been established to end poverty, protect the planet, and ensure prosperity for all. Delivery of the Sustainable Development Goals will require a healthy and productive environment. An understanding of the impacts of chemicals which can negatively impact environmental health is therefore essential to the delivery of the Sustainable Development Goals. However, current research on and regulation of chemicals in the environment tend to take a simplistic view and do not account for the complexity of the real world, which inhibits the way we manage chemicals. There is therefore an urgent need for a step change in the way we study and communicate the impacts and control of chemicals in the natural environment. To do this requires the major research questions to be identified so that resources are focused on questions that really matter. We present the findings of a horizon-scanning exercise to identify research priorities of the European environmental science community around chemicals in the environment. Using the key questions approach, we identified 22 questions of priority. These questions covered overarching questions about which chemicals we should be most concerned about and where, impacts of global megatrends, protection goals, and sustainability of chemicals; the development and parameterization of assessment and management frameworks; and mechanisms to maximize the impact of the research. The research questions identified provide a first-step in the path forward for the research, regulatory, and business communities to better assess and manage chemicals in the natural environment. Environ Toxicol Chem 2018;9999:1-15. C 2018 SETAC
... However, feeding patterns are more complicated than the simple feeding guild classification and are better represented by a fuzzy coded system (Chevenet et al., 1994;Moog, 1995). Fuzzy coded traits have been used as response metrics in various biomonitoring contexts (Arce et al., 2014;Archaimbault et al., 2009;Culp et al., 2011;Mondy and Usseglio-Polatera, 2014; Van den Brink et al., 2013) but also in the estimation of the exposure to organic pollutants (Ippolito et al., 2012;Liess et al., 2008). This estimation of the exposure was only applied to single species and has not yet been generalized for an entire community. ...
... These models, despite presenting different levels of complexity, involve parameters having a rather clear physical or biological meaning (Jager et al., 2011), but intermittent exposure implies the possibility for recovery at population level (Ippolito et al., 2010;Focks et al., 2014). Hence, when aiming at increasing the ecological realism of risk assessment, addressing the effects at the individual level is not sufficient, and population models can represent a suitable approach (Ashauer and Brown, 2013;Van den Brink et al., 2013). However, mechanistic effect models show two main limitations, i.e., (1) they are not linked to each other, and therefore each of them focuses on one single population, whereas in reality interactions between species within a community might strongly influence the sign and size of ecological effects, and (2) they are not directly linked to space and time-explicit fate and exposure models . ...
Abstract The use of plant protection products (PPPs) in agricultural areas implies potential chemical loadings to surface waters, which can pose a risk to aquatic ecosystems and human health. Due to the spatio-temporal variability of PPP applications and of the processes regulating their transport to surface waters, aquatic organisms are typically exposed to pulses of contaminants. In small mountain watersheds, where runoff fluxes are more rapid due to the steep slopes, such exposure peaks are particularly likely to occur. In this work, a spatially explicit, dynamic model for predicting pesticide exposure in surface waters of cultivated mountain basins (DynAPlus) has been developed. The model has been applied to a small mountain watershed (133 km2) located in the Italian Eastern Alps and characterized by intensive agriculture (apple orchards) around the main river and its tributaries. DynAPlus performance was evaluated for chlorpyrifos through experimental monitoring, using samples collected during the 2011 and 2012 productive seasons. The comparison between predictions and measurements resulted in a good agreement (R2 = 0.49, efficiency factor 0.60), although a more accurate spatial information in the input scenario (e.g., field-specific applications, rainfall amount, soil properties) would dramatically improve model performance. A set of illustrative simulations performed for three PPPs highlighted the potential role of DynAPlus in improving exposure predictions for ecological risk assessment and pesticide management practices (e.g., for active ingredient and application rate selection), as well as for planning efficient monitoring campaigns and/or interpreting monitoring data. However, some model improvements (e.g., solid erosion and transport) and a more thorough model validation are desirable to enlarge the applicability domain.
... Molecular characteristics, such as sensitivity and adaptability to agrochemicals represent an interesting opportunity for future trait categorisation (e.g. Liess, Schäfer & Schriever, 2008; see Van den Brink et al., 2013, for approaches to aquatic systems), as do holobiont-associated traits that consider microbial symbionts of insects in identifying environmental responses such as heat resistance (and trophic interactions with plants and parasites) (e.g. Feldhaar, 2011). ...
Ecological studies are increasingly moving towards trait-based approaches, as the evidence mounts that functions, as opposed to taxonomy, drive ecosystem service delivery. Among ecosystem services, biological control has been somewhat overlooked in functional ecological studies. This is surprising given that, over recent decades, much of biological control research has been focused on identifying the multiple characteristics (traits) of species that influence trophic interactions. These traits are especially well developed for interactions between arthropods and flowers – important for biological control, as floral resources can provide natural enemies with nutritional supplements, which can dramatically increase biological control efficiency. Traits that underpin the biological control potential of a community and that drive the response of arthropods to environmental filters, from local to landscape-level conditions, are also emerging from recent empirical studies. We present an overview of the traits that have been identified to (i) drive trophic interactions, especially between plants and biological control agents through determining access to floral resources and enhancing longevity and fecundity of natural enemies, (ii) affect the biological control services provided by arthropods, and (iii) limit the response of arthropods to environmental filters, ranging from local management practices to landscape-level simplification. We use this review as a platform to outline opportunities and guidelines for future trait-based studies focused on the enhancement of biological control services.
... actual population size and habitat preference) is required. These data would allow predicting responses of organisms to anthropogenic stressors in environmental risk assessments (EFSA SC Panel, 2016b;van den Brink et al., 2013). ...
... actual population size and habitat preference) is required. These data would allow predicting responses of organisms to anthropogenic stressors in environmental risk assessments (EFSA SC Panel, 2016b;van den Brink et al., 2013). ...
Current approaches to risk assessment in bees do not take into account co-exposures from multiple stressors. The European Food Safety Authority (EFSA) is deploying resources and efforts to move towards a holistic risk assessment approach of multiple stressors in bees. This paper describes the general principles of pesticide risk assessment in bees, including recent developments at EFSA dealing with risk assessment of single and multiple pesticide residues and biological hazards. The EFSA Guidance Document on the risk assessment of plant protection products in bees highlights the need for the inclusion of an uncertainty analysis, other routes of exposures and multiple stressors such as chemical mixtures and biological agents. The EFSA risk assessment on the survival, spread and establishment of the small hive beetle, Aethina tumida, an invasive alien species, is provided with potential insights for other bee pests such as the Asian hornet, Vespa velutina. Furthermore, data gaps are identified at each step of the risk assessment, and recommendations are made for future research that could be supported under the framework of Horizon 2020. Finally, the recent work conducted at EFSA is presented, under the overarching MUST-B project (“EU efforts towards the development of a holistic approach for the risk assessment on MUltiple STressors in Bees”) comprising a toolbox for harmonised data collection under field conditions and a mechanistic model to assess effects from pesticides and other stressors such as biological agents and beekeeping management practices, at the colony level and in a spatially complex landscape. Future perspectives at EFSA include the development of a data model to collate high quality data to calibrate and validate the model to be used as a regulatory tool. Finally, the evidence collected within the framework of MUST-B will support EFSA's activities on the development of a holistic approach to the risk assessment of multiple stressors in bees. In conclusion, EFSA calls for collaborative action at the EU level to establish a common and open access database to serve multiple purposes and different stakeholders.
... Trait-based approaches have recently also been advocated as promising tools also in ecotoxicology and environmental risk assessment of chemical substances (Rubach et al. 2011; Van den Brink et al. 2013). ...
Trait‐based approaches are increasingly being used to test mechanisms underlying species assemblages and biotic interactions across a wide range of organisms including terrestrial arthropods and to investigate consequences for ecosystem processes. Such an approach relies on the standardized measurement of functional traits that can be applied across taxa and regions. Currently, however, unified methods of trait measurements are lacking for terrestrial arthropods and related macroinvertebrates (terrestrial invertebrates hereafter).
Here, we present a comprehensive review and detailed protocol for a set of 29 traits known to be sensitive to global stressors and to affect ecosystem processes and services. We give recommendations how to measure these traits under standardized conditions across various terrestrial invertebrate taxonomic groups.
We provide considerations and approaches that apply to almost all traits described, such as the selection of species and individuals needed for the measurements, the importance of intraspecific trait variability, how many populations or communities to sample and over which spatial scales.
The approaches outlined here provide a means to improve the reliability and predictive power of functional traits to explain community assembly, species diversity patterns and ecosystem processes and services within and across taxa and trophic levels, allowing comparison of studies and running meta‐analyses across regions and ecosystems.
This handbook is a crucial first step towards standardizing trait methodology across the most studied terrestrial invertebrate groups, and the protocols are aimed to balance general applicability and requirements for special cases or particular taxa. Therefore, we envision this handbook as a common platform to which researchers can further provide methodological input for additional special cases.
A lay summary is available for this article.
... In fact, a recent study suggests that we can use food web theory and models to predict both the effects of individual contaminants and contaminant mixtures on communities by knowing something about the direct toxicities of the contaminant to the species and the directions and strengths of species interactions (Halstead et al. 2014). This, coupled with evidence that species traits (Baird & Van den Brink 2007;Van den Brink et al. 2013) and phylogenies of chemicals and species can be used to predict the toxicities of untested chemicals and species (Guenard et al. 2011;Hammond et al. 2012;Guenard et al. 2014) and the development of mathematical network models for community dynamics (USEPA 2000;Dunne et al. 2002;Ebenman & Jonsson 2005), offers hope that this criticism will be less of a hurdle to predicting effects of contaminants on communities in the future (Rohr, Kerby, et al. 2006). Additionally, many of these same critiques levied at mesocosm studies, such as the critique that the results will depend on the species and environmental conditions tested, can be applied to all levels of biological organization. ...
Ecological risk assessment (ERA) is the process used to evaluate the safety of manufactured chemicals to the environment. Here we review the pros and cons of ERA across levels of biological organization, including suborganismal (e.g., biomarkers), individual, population, community, ecosystem and landscapes levels. Our review revealed that level of biological organization is often related negatively with ease at assessing cause-effect relationships, ease of high-throughput screening of large numbers of chemicals (it is especially easier for suborganismal endpoints), and uncertainty of the ERA because low levels of biological organization tend to have a large distance between their measurement (what is quantified) and assessment endpoints (what is to be protected). In contrast, level of biological organization is often related positively with sensitivity to important negative and positive feedbacks and context dependencies within biological systems, and ease at capturing recovery from adverse contaminant effects. Some endpoints did not show obvious trends across levels of biological organization, such as the use of vertebrate animals in chemical testing and ease at screening large numbers of species, and other factors lacked sufficient data across levels of biological organization, such as repeatability, variability, cost per study and cost per species of effects assessment, the latter of which might be a more defensible way to compare costs of ERAs than cost per study. To compensate for weaknesses of ERA at any particular level of biological organization, we also review mathematical modeling approaches commonly used to extrapolate effects across levels of organization. Finally, we provide recommendations for next generation ERA, submitting that if there is an ideal level of biological organization to conduct ERA, it will only emerge if ERA is approached simultaneously from the bottom of biological organization up as well as from the top down, all while employing mathematical modeling approaches where possible to enhance ERA. Because top-down ERA is unconventional, we also offer some suggestions for how it might be implemented efficaciously. We hope this review helps researchers in the field of ERA fill key information gaps and helps risk assessors identify the best levels of biological organization to conduct ERAs with differing goals.
... The recovery rate of aquatic populations after pesticide stress largely depends on the landscape configuration (e.g., connectivity, presence of refugees) and on the reproductive rates and the recolonization abilities of the impacted populations [7][8][9][10][11]. Recently, trait-based approaches have been introduced in ecotoxicology and ecological risk assessment as promising tools to characterize the intrinsic sensitivity and recovery potential of aquatic organisms [12][13][14]. For instance, Rubach et al. [15] were able to perform trait-based regressions that explain up to 70% of the invertebrate's sensitivity variation to 3 groups of insecticides (pyrethroids, organophosphates, carbamates). ...
In this study we evaluated the vulnerability of aquatic invertebrates to insecticides based on their intrinsic sensitivity and their population-level recovery potential. The relative sensitivity of invertebrates to five different classes of insecticides was calculated at the genus, family and order levels using the acute toxicity data available in the USEPA AQUIRE database. Biological trait information was linked to the calculated relative sensitivity to evaluate correlations between traits and sensitivity and to calculate a vulnerability index, which combines intrinsic sensitivity and traits describing the recovery potential of populations partially exposed to insecticides (e.g. voltinism, flying strength, occurrence in drift). Our analysis shows that the relative sensitivity of arthropods depends on the insecticide mode-of-action. Traits such as degree of sclerotization, size and respiration type showed good correlation to sensitivity and can be used to make predictions for invertebrate taxa without a priori sensitivity knowledge. The vulnerability analysis revealed some EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa as vulnerable to all insecticide classes and pointed particular gastropods and bivalves as potentially vulnerable. Microcrustaceans (e.g. daphnids, copepods) showed low potential vulnerability, particularly in lentic ecosystems. The methods described here can be used for the selection of focal species to be included as part of ecological scenarios and higher-tier risk assessments. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
... If mode of action (MoA)-specific species traits can be identified, biomonitoring data could be used as a marker for chemical stress at the aggregating MoA level. This assessment can also be used to identify the chemicals likely to pose the highest ecological risks (Van den Brink et al., 2013). ...
... Population resilience (versus susceptibility) to environmental stressors is governed by life-144 history traits relating to reproductive strategy, longevity, dispersal, niche specificity, 145 demographics and dynamic stock-recruitment [22,[36][37]. A key challenge in ERA is 146 determining whether or not physiological effects in individuals translate to adverse impacts on 147 wild populations [16,38]. This extrapolation between effect-levels and between species has 148 been attempted using population dynamics models, which project forward the life-histories of 149 wild populations, with and without superimposing chemical effects measured in surrogate, 150 laboratory-exposed populations. ...
Fish represent the planet’s most diverse group of vertebrates and they can be exposed to a wide range of pharmaceuticals. For practical reasons, extrapolation of pharmaceutical effects from ‘model’ species to other fish species is adopted in risk assessment. Here, we critically assess this approach. First, we show that between 65% and 86% of human drug targets are evolutionarily conserved in 12 diverse fish species. Focusing on nuclear steroid hormone receptors, we further show that the sequence of the ligand binding
domain that plays a key role in drug potency is highly conserved, but there is variation between species. This variation for the oestrogen receptor, however, does not obviously account for observed differences in receptor
activation. Taking the synthetic oestrogen ethinyloestradiol as a test case, and using life-table-response experiments, we demonstrate significant reductions in population growth in fathead minnow and medaka, but not zebrafish, for environmentally relevant exposures. This finding contrasts with zebrafish being ranked as more ecologically susceptible, according to two independent life-history analyses. We conclude that while most drug targets are conserved in fish, evolutionary divergence in drug-target activation,
physiology, behaviour and ecological life history make it difficult to predict population-level effects. This justifies the conventional use of at least a x10 assessment factor in pharmaceutical risk assessment, to account for differences in species susceptibility.
... Typically, environmental exposure and the expected ecological effects are assessed separately, following procedures laid down in guidance documents (EFSA Panel on Plant Protection Products and their Residues 2013; European Chemicals Agency 2011, 2013; European Medicines Agency 2004). For the last 25 years, the environmental realism, the ecological relevance, and the methodological accuracy of these procedures have been questioned (Cairns 1988;Forbes and Calow 2002;Van Straalen 2003;Van den Brink 2008;De Laender et al. 2008a; Van den Brink et al. 2013;Di Guardo and Hermens 2013). Bearing in mind the ecological and environmental complexity inherent to natural ecosystems, risk assessors increasingly realise that ecological risk cannot be adequately assessed using procedures that disregard most, if not all, of this complexity. ...
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.
... Trait-based approaches represent a promising tool capable of complementing taxonomically-based assessments with functionally-based assessment [58]. At present, they represent a tool for the analysis of population vulnerability and for many other approaches relevant for ERA [59]. One of the bottlenecks for the development and application of the approach is the lack of data for the precise characterization of suitable traits, particularly for traits describing detailed anatomic characteristics, as well as physiologic or metabolic patterns. ...
The usual procedures for ecological risk assessment (ERA) have been based for decades on simplified approaches in order to provide basic information on the huge amount of chemicals introduced into the environment. These approaches allowed the development of international regulatory tools capable of substantially reducing the adverse effects on ecosystems in developed countries. Nevertheless, these approaches suffer from a lack of ecological realism and are poorly suitable for understanding the actual consequences for ecosystem health. The need for more ecologically-based approaches is now recognized by the scientific community and has been highlighted by a recent document of the European Commission. In this paper, a synthesis is presented of the most important issues and the need for research to improve the ecological realism of exposure and effect assessment and the tools that should be developed to reach this objective. In particular, the major challenges are the following: the effects of variable exposure patterns; the vulnerability of ecosystems; the indirect ecological effects; the responses to multiple stress factors; the improvement of ecological modeling. The possibilities for using new scientific achievements in regulatory ERA are also discussed.
Urban regions are rapidly expanding worldwide resulting in biotic homogenization and loss of ecological functions in urban ecosystems due to management practices targeting at satisfying aesthetic and health demands of urban residents. These practices also modify living conditions and food recourses of soil invertebrates thereby affecting the structure and functional diversity of soil animal communities including collembolans. Here, we assessed the response of the community composition and functional diversity of collembolans as a major component of soil food webs to urbanization (suburban vs urban region) and greenspace types (including forest and four park-associated greenspaces: lawn, lawn with shrubs, lawn with trees, and lawn with shrubs and trees). Our results highlight that both urbanization and greenspace type significantly affect soil properties and community structure of collembolans. The negative effect of urbanization and park-associated greenspaces on species and functional composition of collembolan communities were likely due to both changes in soil abiotic conditions and bacterial community composition, whereas the reduction of collembolan functional traits likely resulted from changes in soil abiotic conditions and fungal community composition. In park-associated greenspaces richness and diversity of bacterial communities were highest in lawns with trees and lowest in forests. By contrast, species richness and diversity of fungal communities were highest in lawns with shrubs, but, similar to bacteria, lowest in forests. Community composition and functional traits of collembolans were more homogeneous in urban than suburban greenspaces pointing to reduced functioning of collembolan assemblages in urban areas. Overall, our results suggest that changes in soil properties and bacterial communities caused by urbanization and greenspace type are important factors contributing to taxonomic homogenization of collembolan communities, while the loss of functional traits of collembolan communities in urban greenspaces is likely caused by changes in soil properties and fungal community composition.
Synthetic gene drives are transgenic constructs that aim to bias heredity and thereby influence the characteristics and fate of populations regarding abundance and evolution. Aside from irreversible effects in ecosystems that could be triggered by the release of a gene drive, research on confinable drives or even the reversibility of gene drives is underway and shows first success under laboratory conditions. However, their effectiveness under realistic conditions is not entirely clear unless first test releases have taken place. Since a potentially irreversible intervention into ecosystems is created, a prospective assessment is needed. We present an approach of prospective ecological vulnerability analysis for the proposed control of the invasive pest Drosophila suzukii by using gene drives. The analysis considers the accidental spread of the gene drive to the native habitat of Drosophila suzukii, with a focus on Japan. It contains a mapping of potential impacts as a consequence of the suppression of the insect. Multiple cascading effects were identified including the potential spread of the gene drive in geographic range or potential hybridization with non-target species. Determining the vulnerability of an ecosystem requires information regarding specific characteristics at different organizational levels. The vulnerability analysis of an affected ecosystem will initially serve to identify gaps in knowledge. Reducing complexity and breaking down the potential events that might arise from a gene drive population suppression enables to better understand endpoints i.e. concrete effects. Three potential effects have been selected for a specific analysis of the vulnerability of populations and species. A high vulnerability was obtained for the suppression of non-target (native) populations of Drosophila suzukii as well as for a decrease in specialized parasitoid abundance. The paper proposes the outline of a comprehensive prospective approach to understand the susceptibility of an ecosystem to unintended and irreversible harm.
Previous studies have explored effects of imidacloprid and its metabolites on terrestrial species, such as bees, and indicated the importance of some active metabolites. However, the biotransformation of IMI and the toxicity of its metabolites to aquatic arthropods are largely unknown, especially the mechanisms driving species sensitivity differences and time-cumulative toxicity effects. To assess the potential effects of the metabolization of IMI and the toxicokinetics and toxicity of the metabolite(s) on aquatic arthropods, we first studied the acute toxicity of IMI and relevant metabolites to the mayfly species Cloen dipterum (sensitive to IMI) and the amphipod species Gammarus pulex (less sensitive to IMI). Secondly, toxicokinetic experiments were conducted using both the parent compound and imidacloprid-olefin (IMI-ole), a metabolite assessed as toxic in the acute tests and defined as bioactive. Of the four tested metabolites, only IMI-ole was readily biotransformed from the parent IMI and showed similar toxicity to C. dipterum as IMI. However, C. dipterum was hardly able to eliminate IMI-ole from its body. For G. pulex, IMI-ole was also the only detected metabolite causing toxicity, but the biotransformation of IMI to IMI-ole was slower and lower in G. pulex compared to C. dipterum, and G. pulex eliminated IMI-ole quicker than C. dipterum. Our results on internal kinetics of IMI and IMI-ole, and on biotransformation of IMI indicated that the metabolite IMI-ole was toxic and was rather persistent inside the body tissue of both invertebrate species, especially for C. dipterum. In conclusion, as IMI and IMI-ole have similar toxicity and IMI was replaced rapidly by IMI-ole which in turn was poorly eliminated by C. dipterum, the overall toxicity is a function of dose and time. As a result, no long-term threshold of effects of IMI may exist for C. dipterum as the poor elimination results in an ongoing increase of toxicity over time for mayflies as also found experimentally in previous published papers.
Environmental challenges persist across the world, including the Australasian region of Oceania, where biodiversity hotspots and unique ecosystems such as The Great Barrier Reef are common. These systems are routinely affected by multiple stressors from anthropogenic activities, and increasingly influenced by global megatrends (e.g., the food – energy – water nexus, demographic transistions to cities) and climate change. Here we report priority research questions from the Global Horizon Scanning Project, which aimed to identify, prioritize and advance environmental quality research needs from an Australasian perspective, within a global context. We employed a transparent and inclusive process of soliciting key questions from Australasian members of the Society of Environmental Toxicology and Chemistry. Following submission of 78 questions, 20 priority research questions were identified during an expert workshop in Nelson, New Zealand. These research questions covered a range of issues of global relevance, including research needed to: more closely integrate ecotoxicology and ecology for the protection of ecosystems; increase flexibility for prioritizing chemical substances currently in commerce; understand the impacts of complex mixtures and multiple stressors; and define environmental quality and ecosystem integrity of temporary waters. Some questions have specific relevance to Australasia, particularly the uncertainties associated with using toxicity data from exotic species to protect unique indigenous species. Several related priority questions deal with the theme of how widely international ecotoxicological data and databases can be applied to regional ecosystems. Other timely questions, which focus on improving predictive chemistry and toxicology tools and techniques, will be important to answer several of the priority questions identified here. Another important question raised was how to protect local cultural and social values and maintain indigenous engagement during problem formulation and identification of ecosystem protection goals. Addressing these questions will be challenging, but doing so promises to advance environmental sustainability in Oceania and globally. This article is protected by copyright. All rights reserved.
Risk assessment and management of pesticides are directly related to sustainable agriculture concept because, besides playing an important role in intensified agriculture by protecting crops from pests and diseases and reducing competition from weeds, the use of pesticides can cause human health and ecological problems. Several pesticides have been shown to reduce water quality and result in adverse effects to sensitive organisms, aquatic ecosystems, and human health. Pesticides enter water systems through different pathways, and therefore, it is important to understand the environmental behavior and fate of pesticides and assess their potential exposure and associated risks to the environment. Ecological risk assessment—ERA—has been adopted in many countries for regulatory purpose and as basis for management of pesticides. Models can be used during different stages of the ERA process and include fate-exposure models, exposure-effect models, and integrated models. In this chapter, definitions of ERA are stated. Pesticide environmental behavior processes and modeling approaches are briefly discussed. Tools for ecological exposure characterization in the regulatory context of agricultural pesticides concerning surface water and groundwater bodies are presented.
The protection of listed species through the Ecological Risk Assessment (ERA) process is encumbered by the number and diversity of species that need protection and the limited data available to inform assessments. Ecological communities within isolated ecosystems often contain a number of biologically diverse endemic, endangered, and threatened species, as well as providing numerous ecosystem services (ES). We propose an approach that develops community-level protection goals using isolated wetlands that includes both listed species and Service Providing Units (SPUs) that drive ES for ecological risk assessments (ERAs). Community-level protection goals are achieved by developing a protection community and weighing lines of evidence to determine a set of focal species within that community upon which to base the assessment. Lines of evidence include chemical mechanism of action, likely routes of exposure, and taxa susceptibility, as well as relationships among species, and other ecological factors. We demonstrate the process using case studies of chlorpyrifos in California vernal pools and coal ash effluent in Carolina bays. In the California vernal pool case study, listed species were the primary SPUs for the ES provided by the critical habitat. The weight of evidence demonstrated the honey bee as the focal species for the terrestrial environment and the vernal pool fairy shrimp as the focal species for the aquatic environment. The protection community within the Carolina bay case study was more taxonomically diverse than vernal pools for both listed species and SPUs, with amphibians identified as the focal species for which to target mitigation goals and hazard levels. The approach presented here will reduce the time and resource investment required for assessment of risk to listed species and adds an ES perspective to demonstrate value of assessments beyond listed species concerns.
Determining causality of sediment toxicity is of great importance in aquatic risk assessment, but there are tremendous challenges due to joint toxicity of trace pollutants in complex sediment matrices. Two approaches, namely toxicity identification evaluation (TIE) and effect-directed analysis (EDA) have been developed. Conventional sediment TIEs take the advantage of environmental relevance by using whole organism bioassays; however, they suffer from lack of effective methods for specifically identifying major contributors as it typically only evaluates contaminant class rather than specific contaminants. Alternatively, EDA is a powerful tool in identifying causes of sediment toxicity with sophisticated fractionation and chemical analysis of targeted and non-targeted non-polar organic toxicants, but it is not always environmentally relevant due to the use of in-vitro bioassays and exhaustive solvent extraction. An integrated TIE and EDA method would provide an environmentally relevant and toxicant specific approach to effectively determine causality of sediment toxicity by combining the merits of the two methods. Bioavailability-based extraction and dosing techniques are recommended to be incorporated into the integrated method to improve the accuracy of toxicity diagnosis. Besides considering bioavailability in the integrated TIE and EDA approach, the premise of adverse outcome pathways should also be considered. Generally speaking, both TIE and EDA have focused on adverse effects at cellular and organism levels. The addition of trait-based approaches in screening multiple toxicological endpoints helps to extend effects on cellular and organism levels to population level, and provides a better understanding of potential impacts to the community and ecosystem. The outcome pathway underlies the critical role of determining causality in interpreting impacts of complex mixtures to benthic community and aquatic ecosystem.
EFSA performs environmental risk assessments (ERAs) for single potential stressors such as plant protection products, genetically modified organisms and feed additives and for invasive alien species that are harmful for plant health. In this risk assessment domain, the EFSA Scientific Committee recognises the importance of more integrated ERAs considering both the local and landscape scales, as well as the possible co-occurrence of multiple potential stressors that fall under the remit of EFSA, which are important when addressing ecological recovery. In this scientific opinion, the Scientific Committee gathered scientific knowledge on the potential for the recovery of non-target organisms for the further development of ERA. Current EFSA guidance documents and opinions were reviewed on how ecological recovery is addressed in ERA schemes. In addition, this scientific opinion is based on expert knowledge and data retrieved from the literature. Finally, the information presented in this opinion was reviewed by experts from the relevant EFSA Panels, European risk assessment bodies and through an open consultation requesting input from stakeholders. A conceptual framework was developed to address ecological recovery for any assessed products, and invasive alien species that are harmful for plant health. This framework proposes an integrative approach based on well-defined specific protection goals, scientific knowledge derived by means of experimentation, modelling and monitoring, and the selection of focal taxa, communities, processes and landscapes to develop environmental scenarios to allow the assessment of recovery of organisms and ecological processes at relevant spatial and temporal scales.
The EFSA performs environmental risk assessment (ERA) for single potential stressors such as plant protection products, genetically modified organisms and feed additives, and for invasive alien species that are harmful to plant health. This ERA focusses primarily on the use or spread of such potential stressors in an agricultural context, but also considers the impact on the wider environment. It is important to realise that the above potential stressors in most cases contribute a minor proportion of the total integrated pressure that ecosystems experience. The World Wildlife Fund listed the relative attribution of threats contributing to the declines in animal populations as follows: 37% from exploitation (fishing, hunting, etc.), 31% habitat degradation and change, 13% from habitat loss, 7% from climate change, and only 5% from invasive species, 4% from pollution and 2% from disease. In this scientific opinion, the Scientific Committee gathered scientific knowledge on the extent of coverage of endangered species in current ERA schemes that fall under the remit of EFSA. The legal basis and the relevant ecological and biological features used to classify a species as endangered are investigated. The characteristics that determine vulnerability of endangered species are reviewed. Whether endangered species are more at risk from exposure to potential stressors than other non-target species is discussed, but specific protection goals for endangered species are not given. Due to a lack of effect and exposure data for the vast majority of endangered species, the reliability of using data from other species is a key issue for their ERA. This issue and other uncertainties are discussed when reviewing the coverage of endangered species in current ERA schemes. Potential tools, such as population and landscape modelling and trait-based approaches, for extending the coverage of endangered species in current ERA schemes, are explored and reported.
The manuscript is the Foreword of the Special Series on "New Challenges in ERA", of which I am Guest Editor, highlighting the need for a substantial improvement for the future of ERA. It explains the reasons in support of the scientific interest of the Special Series and describes very shortly the main topics treated in the different papers. Integr Environ Assess Manag © 2013 SETAC.
Habitat fragmentation may adversely affect the ability of natural enemies to control pest outbreaks in agricultural landscapes by interfering with their search behavior and ability to aggregate in response to prey. We determined how landscape structure affected
the ability of two ladybird beetles (Coleoptera: Coccinellidae) to track aphid populations in experimental landscapes that differed in the abundance and degree of fragmentation of red clover (Trifolium pratense). One coccinellid was a native species (Coleomegilla maculata Pallas) and the other (Harmonia axiridis Timberlake) was introduced specifically for the biological control of crop pests such as pea aphids (Acyrrlzosiphon pisurn Harris; Homoptera: Aphididae).
Landscape structure exhibited a threshold in lacunarity (a measure of interpatch distances) below 20% habitat. at which point clover patches became significantly more isolated. This threshold in landscape structure was mirrored by a similar threshold in the distribution of pea aphid populations. The distribution of the biocontrol agent, H. axyridis, tracked this threshold in aphid distribution, but the native coccinellid, C. maculata, was unable to do
so in fragmented clover landscapes. Although C. maculata was a more active forager within clover cells, overall it was less mobile and moved significantly less among clover cells and between landscapes than H. axyridis, which may have contributed to its inability to track
aphid populations in fragmented landscapes. The two coccinellids did not differ in their search success within fragmented landscapes. however. and it was only in clumped landscapes that H. axyridis maximized search success and foraged within clover cells that had
2.5-3 times more aphids than those in which C. maculata occurred.
Thus, the potential of predators to control pest populations in fragmented landscapes may ultimately reflect the extent to which thresholds in landscape structure interfere with the aggregative response of predators. In this system, the aggregative response of coccinellids was more closely tied to thresholds in the distribution of clover than aphids. With its greater mobility, H. axyridis was more effective than the indigenous C. maculata at tracking aphids when they occurred at low patch occupancy (below the threshold in landscape structure), which is a requisite for successful biocontrol. If native insect predators are generally more sensitive to habitat fragmentation, greater reliance may be placed on the introduction of exotic species for biocontrol, which is not without economic cost and
potential ecological impacts to native insect communities. Our study demonstrates that, in addition to economic thresholds, there are also ecological thresholds that must be surmounted if biocontrol measures are to be successful. In addition to enhancing vegetational diversity within agroecosystems, conservation biological control should also strive to mitigate fragmentation effects on natural enemies, especially if thresholds in landscape structure disrupt predator-prey interactions and compromise the efficacy of biocontrol programs.
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.
We investigated the ability of the North Carolina Biotic Index (NCBI) and the Ephemeroptera + Plecoptera + Trichoptera (EPT) index to track an experimental ma- nipulation of the invertebrate community and resultant alteration of several ecosystem-level processes in a headwater stream at the Coweeta Hydrologic Laboratory in western North Carolina. Indices were calculated from quantitative monthly or bimonthly benthic samples of moss-covered rockface and mixed substrate habitats, as well as habitat-weighted values based on the proportion of each habitat in the two streams. One stream (C 55) served as a reference stream over the 6-yr period of late 1984 through 1990, whereas the other (C 54) received seasonal treatments with an insecticide for 3 yr (1986-1988). Throughout pretreatment, treatment, and recovery, both the NCBI and EPT indices tracked the distur- bance regime of the treatment stream. Indices for the reference stream varied little during the 6-yr period. Both the NCBI and EPT suggested strong changes in the treatment stream during treatment relative to both pretreatment and the reference stream. Following cessation of insecticide treatments, both indices reflected improved biotic conditions during first and second years of recovery in C 54. Compared with fauna of mixed substrates, rockface fauna had lower (better) NCBI values during pretreatment, and exhibited a greater proportional increase in tolerant taxa during treatment than mixed substrates, emphasizing the importance of including rockface communities in environmental monitoring programs. Changes in both the EPT and NCBI indices closely corresponded to changes in ecosystem- level processes observed in C 54 from pretreatment to treatment, and recovery periods. These processes include: leaf litter processing rates, organic matter storage, fine paniculate organic matter generation and export, and secondary production. With the exception of organic matter storage, all of these processes declined during treatment of C 54, and subsequently increased during recovery. Our results demonstrate the potential of such indices to detect and monitor stream ecosystem changes during and following disturbance. The EPT index was by far the easiest to use from both the standpoint of time required for sample processing and ease of application. Compared with the labor-intensive sample processing, specimen identification and measurement, and data entry required for secondary production calculations, the EPT index was relatively simple and displayed a remarkable ability to track secondary production of invertebrates in the treatment stream. Our data strongly support the inclusion of the EPT and NCBI indices in these southern Appalachian headwater streams as indicators of both degradation and recovery of stream ecosystem processes from chemical-induced disturbance.
The use of species traits to characterize the functional composition of benthic invertebrate communities has become well established in the ecological literature. This approach holds much potential for predicting changes of both species and species assemblages along environmental gradients in terms of traits that are sensitive to local environmental conditions. Further, in the burgeoning field of biomonitoring, a functional approach provides a predictive basis for understanding community-level responses along gradients of environmental alteration caused by humans. Despite much progress in recent years, the full potential of the functional traits-based approach is currently limited by several factors, both conceptual and methodological. Most notably, we lack adequate understanding of how individual traits are intercorrelated and how this lack of independence among traits reflects phylogenetic (evolutionary) constraint. A better understanding is needed if we are to make the transition from a largely univariate approach that considers single-trait responses along single environmental gradients to a multivariate one that more realistically accounts for the responses of many traits across multiple environmental gradients characteristic of most human-dominated landscapes. Our primary objective in this paper is to explore the issue of inter-trait correlations for lotic insects and to identify opportunities and challenges for advancing the theory and application of traits-based approaches in stream community ecology. We created a new database on species-trait composition of North American lotic insects. Using published accounts and expert opinion, we collected information on 20 species traits (in 59 trait states) that fell into 4 broad categories: life-history, morphological, mobility, and ecological. First, we demonstrate the importance of considering how the linkage of specific trait states within a taxon is critical to developing a more-robust traits-based community ecology. Second, we examine the statistical correlations among traits and trait states for the 311 taxa to identify trait syndromes and specify which traits provide unique (uncorrelated) information that can be used to guide trait selection in ecological studies. Third, we examine the evolutionary associations among traits by mapping trait states onto a phylogentic tree derived from morphological and molecular analyses and classifications from the literature. We examine the evolutionary lability of individual traits by assessing the extent to which they are unconstrained by phylogenic relationships across the taxa. By focusing on the lability of traits within lotic genera of Ephemeroptera, Plecoptera, and Trichoptera, taxa often used as water-quality indicators, we show how a traits-based approach can allow a priori expectations of the differential response of these taxa to specific environmental gradients. We conclude with some ideas about how specific trait linkages, statistical correlations among traits, and evolutionary lability of traits can be used in combination with a mechanistic understanding of trait response along environmental gradients to select robust traits useful for a more predictive community ecology. We indicate how these new insights can direct the research in statistical modeling that is necessary to achieve the full potential of models that can predict how multiple traits will respond along multiple environmental gradients.
In ecological analyses of species and community distributions there is interest in
the nature of their responses to environmental gradients and in identifying the most important
environmental variables, which may be used for predicting patterns of biodiversity. Methods
such as random forests already exist to assess predictor importance for individual species and
to indicate where along gradients abundance changes. However, there is a need to extend these
methods to whole assemblages, to establish where along the range of these gradients the
important compositional changes occur, and to identify any important thresholds or change
points. We develop such a method, called ‘‘gradient forest,’’ which is an extension of the
random forest approach. By synthesizing the cross-validated R2 and accuracy importance
measures from univariate random forest analyses across multiple species, sampling devices,
and surveys, gradient forest obtains a monotonic function of each predictor that represents the
compositional turnover along the gradient of the predictor. When applied to a synthetic data
set, the method correctly identified the important predictors and delineated where the
compositional change points occurred along these gradients. Application of gradient forest to
a real data set from part of the Great Barrier Reef identified mud fraction of the sediment as
the most important predictor, with highest compositional turnover occurring at mud fraction
values around 25%, and provided similar information for other predictors. Such refined
information allows for more accurate capturing of biodiversity patterns for the purposes of
bioregionalization, delineation of protected areas, or designing of biodiversity surveys.
Evaluation of the ecological status of river sites in Canada is supported by building models using the reference condition approach. However, geography, data scarcity and inter-operability constraints have frustrated attempts to monitor national-scale status and trends. This issue is particularly true in Atlantic Canada, where no ecological assessment system is currently available. Here, we present a reference condition model based on the River Invertebrate Prediction and Classification System approach with regional-scale applicability. To achieve this, we used biological monitoring data collected from wadeable streams across Atlantic Canada together with freely available, nationally consistent geographic information system (GIS) environmental data layers. For the first time, we demonstrated that it is possible to use data generated from different studies, even when collected using different sampling methods, to generate a robust predictive model. This model was successfully generated and tested using GIS-based rather than local habitat variables and showed improved performance when compared to a null model. In addition, ecological quality ratio data derived from the model responded to observed stressors in a test dataset. Implications for future large-scale implementation of river biomonitoring using a standardised approach with global application are presented.
Although the results of ecotoxicological research have had a great influence on environmcntal policy, the scientific basis of the field is still underdeveloped, in particular regarding the formulation of theory and general rules based on causal mechanisms. This is partly due to the fact that the insight in conditions that determine toxicity is much better developed on the side of chemical substances than it is on the side of biological receptors. To strengthen the field of ecotoxicology, it is necessary to know the properties of ecological receptors on which environmental chemicals may act. An ecological receptor may be defined as a species that is vulnerable through a combination of high exposure, inherent sensitivity and weak ability to recover. Sensitivity is determined by processes such as internal distribution of chemicals, metabolism, detoxication and excretion. A possible way to map patterns of sensitivity is to compare the activity of detoxication enzymes such as cytochrome P450 and glutathion-S-transferase. There seem to be differences within the group of terrestrial arthropods, where species with a broad feeding range seem to have the best developed detoxication system. Over the whole animal kingdom it appears that aquatic species on the average have a lower activity than terrestrial species. Ecological effects of environmental toxicants do, however, not only depend on the inherent sensitivity, but also on the population consequences of intoxication, including the ability to recover. A way to express population-level effects may be found in the ratio of the LC50 to the no-effect-level for reproduction; this ratio is called sublethal sensitivity index, SSI. Reviewing data from the terrrestrial environment it may be concluded that SSI varies from 3 to 300, where a high value is characteristic for a susceptible species-toxicant combination. The life-history of a species, which reflects the priorities put in the energy budget during life, may be subject to selection by environmental contaminants; this is exemplified by a study on isopods living in metal-contaminated sites. In conclusion, the biodiversity of ecotoxicological responses requires an evolutionary explanation and the effects of toxic chemicals must be seen in the context of the complex of adaptations of animals to the environment.
The aquatic ecosystem simulation model AQUATOX was parameterized and applied to Contentnea Creek in the coastal plain of North Carolina to determine the response of fish to moderate levels of physical and chemical habitat alterations. Biomass of four fish groups was most sensitive to changes in temperature and detritus, but showed little sensitivity to changes in nutrients, sediment, pH, or dissolved oxygen. The model appears useful for assessment of stream ecosystem response to certain types of stressors; its utility should be determined further by model applications in other study areas and ecoregions.
Agent-based models (ABMs) explicit handling of space and time and integration of nonlinear interactions between system components to create a system response could facilitate realistic risk assessment modeling. We used this approach to evaluate the impact of spatial dynamic factors on a theoretical risk assessment of an insecticide on a carabid beetle population (based on Bembidion lampros). Results indicated that both impacts and recovery were dependent on period of application, area treated, spatial distribution of stressor, beetle dispersal, and underlying habitat suitability. The impact of the stressor was detected far outside the area to which it was applied, and the extent of this impact was affected by beetle dispersal and landscape structure. The results call into question the validity of the recovery endpoint as assessed by field trials because model recovery was primarily influenced by reinvasion, depleting surrounding areas. Despite the simplicity of the acute stressor/Bembidion system modeled, the results obtained were highly variable dependent on the precise inputs used. Therefore, we suggest that application of modeling to risk assessment in the future will require a much more complete description of the risk assessment problem than has hitherto been the case.
Widespread alteration of flow regimes requires guidelines for the protection of river ecosystems based on sound science. Preservation of the biodiversity within river ecosystems and sustaining natural ecological functions are key aspects of their management. However, the relationship between the biota and flow-related phenomena is poorly understood and, as a consequence, over-simplistic hydrology-based guidelines for river management have been adopted without establishing clear indicators of success. In the present paper, we aim to support the improvement of guidelines for flow (current velocity) management by developing a flow sensitivity index based on macroinvertebrates for Canadian rivers. Using benthic macroinvertebrate (BMI) samples collected by the Canadian Aquatic Biomonitoring Network (CABIN), current velocity preferences for the 55 most common invertebrate taxa across a range of reference and potential reference sites were derived. A Canadian Ecological Flow Index (CEFI) was developed based on these preferences. By testing the index against independent data, CEFI was found to respond mainly to changes in hydraulic conditions, and was minimally influenced by confounding factors (e.g. stream type, organic enrichment). The index was further validated using two independent data sets from the west and east of Canada, suggesting countrywide applicability of the method. In conclusion, we have developed a practical approach to evaluate relationships between hydrological regime and an important component of the river biota, permitting the development of an index which has good potential as an indicator for the effects of flow alteration. Moreover, we outline how the CEFI could be used as a tool for the development of holistic guidelines for the estimation of riverine flow needs. Copyright © 2010 Crown in the right of Canada and John Wiley & Sons, Ltd.
PCBs from the Sangamo-Weston Superfund Site near Clemson, South Carolina, USA, were released into the Twelvemile Creek Arm of Lake Hartwell until the early 1990s. Monitoring data have shown that while PCB concentration in sediments declined since 1995, PCB concentrations in fish have remained elevated, e.g., largemouth bass (Micropterus salmoides) concentrations have ranged from 5 to 10 ppm. The EPA aquatic ecosystem model AQUATOX was applied to this system to better characterize foodweb dynamics that lead to biomagnification of PCBs. The model was calibrated with observed fish biomass data. Simulated PCB loading over a 12-year period provided a reasonable fit to observed PCB data in fish. The model demonstrated that contaminated labile detritus loaded to the system was incorporated into the foodweb rather than deposited, thereby maintaining the PCB concentrations in fish while concentrations in the sediment declined. A dominant PCB pathway was from detritus to daphnia to shad to largemouth bass. Fish PCB concentrations showed moderate sensitivity to toxicant parameters; model runs incorporating uncertainty in these parameters predicted recovery (<2ppm PCB) for all species in the range of years from 2008 to 2013. The high sensitivity of the model to parameters related to growth strongly affected PCB concentrations in fish and should be considered in future AQUATOX applications.
To develop theoretical insights into the relationship between spatial pattern and demography, we coupled a spatially structured demographic model with neutral landscape models to investigate how landscape structure aected population persistence and the source±sink potential of landscapes for a generalized, territorial migratory songbird. Four species-types, with dierent sensitivities to habitat area and edge eects, were simulated on replicated landscapes across a range of habitat abundance (1±90%) and frag-mentation or spatial contagion (random, fractal with minimal contagion, and fractal with maximum contagion). For each species-type in each landscape, the expected number of female ospring produced per female (fecundity, b) was modeled as an explicit function of habitat area and spatial structure (patch edge-to-area ratio). Fecundity estimates (b) were combined with survivorship in a life-table analysis to estimate the net lifetime reproductive output (R 0) for the population of each landscape. Landscapes for which R 0 <1 were identi®ed as population sinks, and as potential population sources when R 0 >1. As expected, reproductive output (R 0) was generally highest on fractal landscapes with maximum clumping (minimum fragmentation) and lowest on random landscapes (maximum fragmentation), especially for species with high edge sensitivity. For species with low edge sensitivity, population per-sistence was unlikely when the landscape had <40% habitat (i.e. R 0 <1.0 in these landscapes and were population sinks). Thus, thresholds in population persistence could be identi®ed for dierent species in these landscapes, but the level of habitat required for persistence ranged widely from 5 to 90% depending upon the species' response to habitat fragmentation (edge sensitivity) and the speci®c landscape pattern. Our results caution against the adoption of general rules ocookbook prescriptions' in conservation regarding the amount of habitat required for population persistence (e.g. thè20% rule'). Landscape con®guration (thèdetails of how habitat is arranged') can mitigate the eects of habitat loss and enhance population persistence in fragmented landscapes.
Ecological risk assessment (ERA) has followed a taxonomy-based approach, making the assumption that related species will show similar sensitivity to toxicants, and using safety factors or species sensitivity distributions to extrapolate from tested to untested species. In ecology it has become apparent that taxonomic approaches may have limitations for the description and understanding of species assemblages in nature. Therefore it has been proposed that the inclusion of species traits in ERA could provide a useful and alternative description of the systems under investigation. At the same time, there is a growing recognition that the use of mechanistic approaches in ERA, including conceptual and quantitative models, may improve predictive and extrapolative power. Purposefully linking traits with mechanistic effect models could add value to taxonomy-based ERA by improving our understanding of how structural and functional system facets may facilitate inter-species extrapolation. Here, we explore whether and in what ways traits can be linked purposefully to mechanistic effect models to predict intrinsic sensitivity using available data on the acute sensitivity and toxicokinetics of a range of freshwater arthropods exposed to chlorpyrifos. The results of a quantitative linking of seven different endpoints and twelve traits demonstrate that while quantitative links between traits and/or trait combinations and process based (toxicokinetic) model parameters can be established, the use of simple traits to predict classical sensitivity endpoints yields little insight. Remarkably, neither of the standard sensitivity values, i.e. the LC50 or EC50, showed a strong correlation with traits. Future research in this area should include a quantitative linking of toxicodynamic parameter estimations and physiological traits, and requires further consideration of how mechanistic trait-process/parameter links can be used for prediction of intrinsic sensitivity across species for different substances in ERA.
Electronic supplementary material
The online version of this article (doi:10.1007/s10646-012-0962-8) contains supplementary material, which is available to authorized users.
Biological monitoring and assessment methods have become indispensable tools for evaluating the condition of aquatic and terrestrial ecosystems. When an undesirable biological condition is observed (e.g., a depauperate fish assemblage), its cause (e.g., toxic substances, excess fine sediments, or nutrients) must be determined in order to design appropriate remedial management actions. Causal analysis challenges environmental scientists to bring together, analyze, and synthesize a broad variety of information from monitoring studies, models, and experiments to determine the probable cause of ecological effects. Decision-support systems can play an important role in improving the efficiency, quality and transparency of causal analyses.
The effect of soil moisture on population dynamics of Paronychiurus kimi (Collembola) was examined by combining an empirical soil moisture model with a temperature-sensitive, stage-structured population model. Field observations of soil temperature were used to drive the population model, and simulations were compared to field observations of juvenile and adult densities. Simulations without soil moisture effects produced stable, interyear population dynamics and a significant correlation between simulations and observations (n=12, r
2=0.40, P<0.05) but overestimated densities during much of the year. Adding responses to soil moisture improved the fit between simulations and observations (n=13, r
2=0.40), suggesting that soil moisture is a major limiting factor on field populations of P. kimi. Moreover, an observed temporary decline in field populations during spring could be explained partly by the effects of an herbicide, paraquat (N,N′-dimethyl-gamma,gamma′-bipyridylium dichloride) (r
2=0.45), suggesting that paraquat imposes additional limits on collembolan populations.
Traditional approaches to ecotoxicology and ecological risk assessment frequently have ignored the complexities arising due to the spatial heterogeneity of natural systems. In recent years, however, ecologists have become increasingly aware of the influence of spatial organization on ecological processes. Landscape ecology provides a conceptual and theoretical framework for the analysis of spatial patterns, the characterization of spatial aspects of ecosystem function, and the understanding of landscape dynamics. Incorporating the insights of landscape ecology into ecotoxicology will enhance our ability to understand and ultimately predict the effects of toxic substances in ecological systems. Ecological risk assessments need to explicitly consider multiple spatial scales, accounting for heterogeneity within contaminated areas and for the larger landscape context. A simple simulation model is presented to illustrate the effects of spatial heterogeneity by linking an individual-based toxicokinetic model with a spatially distributed metapopulation model. Dispersal of organisms between contaminated and uncontaminated patches creates a situation where risk analysis must consider a spatial extent broader than the toxicant-contaminated area. In general, the addition of a toxicant to a source patch (i.e., a net exporter of individuals) will have a greater impact than the same toxicant addition to a sink patch (i.e., a net importer of individuals).
This chapter summarizes examples of how food web experiments can improve the understanding of pollution effects from pulp mill and metal mining effluents in complex river environments and how an understanding of the food web aids interpretation of ecological responses to stressor gradients. Assessing pollution impacts in rivers is particularly challenging, because flowing water environments receive multiple, interacting effluent discharges from cities and industries, as well as nonpoint source inputs. Field biomonitoring in rivers is further hindered by uncertainties in estimating exposure to pollutants. River ecologists are faced with the dilemma that large-scale experiments, which incorporate contaminant or nutrient stressors, are not feasible on ethical and practical grounds because they may cause severe acute and chronic effects on riverine communities. In complex environments in situ food experiments can elucidate dose–response relationships between components of the model food web and single or multiple stressors better than standard field observations. The results of ecotoxicological experiments in model food webs can provide a wealth of information on possible species interactions within a community, including knowledge of functional redundancy of species and various indirect effects.
The Dynamic Energy Budget theory unifies the commonalities between organisms, as prescribed by the implications of energetics, and links different levels of biological organisation (cells, organisms and populations). The theory presents simple mechanistic rules that describe the uptake and use of energy and nutrients and the consequences for physiological organisation throughout an organism's life cycle, including the energetics of ageing and contact with toxic compounds. This new edition includes a new chapter on evolutionary aspects, and discusses methods to quantify entropy for living individuals, isotope dynamics, a mechanism behind reserve dynamics, and toxicity of complex mixtures of compounds. An updated ageing module now also applies to demand systems, new methods for parameter estimation, adaptation of substrate uptake, the use of otiliths for reconstruction of food level trajectories, the differentiated growth of body parts (such as tumours and organs) linked to their function, and many more topics. © Cambridge University Press 1993, 2000 and
1. In an ecological approach to risk assessment, population models may play an important role. Our population dynamical models take into account the complex life history of earthworms, as well as a particular ecological interaction (predation). 2. Sublethal impact of pesticides is quantified at the individual level in terms of impaired vital rates, i.e. growth, maturation and reproduction. A simple model for the energetic relationships underlying these vital rates quantifies toxic stress mechanistically through proportionality constants relating size to energetic costs of maintenance, growth, food intake and production of offspring. 3. Risk is defined at the population level. Risk resulting from chronic exposure relates to reductions in (equilibrium) density, changes in population size- and age-structure, and probability of surpassing an extinction threshold. Risk posed by a single or intermittent application of a highly degradable pesticide is defined in terms of extinction probabilities and recovery times, and related to pesticide decay and initial applied dose. 4. The models are individual-based and complementary. A deterministic partial differential equation model is used to derive equilibrium properties of the system analytically and to investigate the general dynamic behaviour. An individual-by-individual model shows how this behaviour is influenced by demographic and environmental stochasticity. 5. Results obtained for two species, Lumbricus rubellus and L. terrestris, indicate that both are sensitive to pesticides affecting the energy available for individual growth, as opposed to the amount of energy available for reproduction. Retarded growth impedes individuals in reaching adulthood. This juvenile delay regulation translates from individual performance to population demography. 6. Life-history characteristics appear to make L. terrestris more sensitive to toxic stress than L. rubellus, resulting in longer population recovery times. 7. The insights obtained from the models and the way results depend on model assumptions, are discussed, and compared to the little available observational and experimental evidence. Extensions enabling a full ecological risk assessment for pesticide use are identified. Establishing an explicit relationship between ambient concentration and individual performance seems mandatory prior to use of the models as predictive tools.
In this paper, we provide a brief review of the well-known methods of reducing spatially structured population models to mean-field models. First, we discuss the terminology of mean-field approximation which is used in the ecological modelling literature and show that the various existing interpretations of the mean-field concept can imply different meanings. Then we classify and compare various methods of reducing spatially explicit models to mean-field models: spatial moment approximation, aggregation techniques and the mean-field limit of IBMs. We emphasize the importance of spatial scales in the reduction of spatially explicit models and briefly consider the inverse problem of scaling up local ecological interactions from microscales to macroscales. Then we discuss the current challenges and limitations for construction of mean-field population models. We emphasize the need for developing mixed methods based on a combination of various reduction techniques to cope with the spatio-temporal complexity of real ecosystems including processes taking place on multiple time and space scales. Finally, we argue that the construction of analytically tractable mean-field models is becoming a key issue to provide an insight into the major mechanisms of ecosystem functioning. We complete this review by introducing the contributions to the current special issue of Ecological Complexity.
The wood mouse is a common and abundant species in agricultural landscape and is a focal species in pesticide risk assessment. Empirical studies on the ecology of the wood mouse have provided sufficient information for the species to be modelled mechanistically. An individual-based model was constructed to explicitly represent the locations and movement patterns of individual mice. This together with the schedule of pesticide application allows prediction of the risk to the population from pesticide exposure. The model included life-history traits of wood mice as well as typical landscape dynamics in agricultural farmland in the UK. The model obtains a good fit to the available population data and is fit for risk assessment purposes. It can help identify spatio-temporal situations with the largest potential risk of exposure and enables extrapolation from individual-level endpoints to population-level effects. Largest risk of exposure to pesticides was found when good crop growth in the “sink” fields coincided with high “source” population densities in the hedgerows.
Models based on Dynamic Energy Budget (DEB) theory offer important advantages in the interpretation of toxicant effects on life-history traits. In contrast to descriptive approaches, they make use of all of the data (all time points, and all endpoints) in one framework, and yield time-independent parameters. In 1996, a suite of simplified DEB models for the analysis of standard toxicity tests was presented under the name ‘DEBtox’. Unfortunately, the original equations contained a few errors and inconsistencies. In this paper, we revisit DEBtox, presenting a new and consistent set of simplified DEB equations. The full derivation is presented in the supplementary material to facilitate critical examination of our work. The simplification is appropriate for situations where body size at the start of investment in reproduction remains constant, as well as the egg costs (and thus hatchling size). These conditions are probably met in many ecotoxicological tests, allowing this framework to be used, at least as a first approach. Additionally, we present a statistical framework for fitting the model to experimental data sets, and to calculate intervals on parameter estimates, model curves and model predictions. As an illustration, we provide a case study for the effects of fluoranthene on Daphnia magna, although the framework is by no means limited to this species or toxicant.
This article describes two general metapopulation models with spatial variation in the sizes of habitat patches. The first model is a simple, nonstructured model that includes the mainland-island and Levins models as two limiting cases. The second model is a structured model explicitly including the size distribution of habitat patches, the size distribution of local populations, and migration among local populations. The models may have up to four equilibria, including two stable, positive equilibria. We discuss the core-satellite species hypothesis in light of these models. This hypothesis predicts that the distribution of patch-occupancy frequencies is bimodal in many species assemblages. We extend the original concept by demonstrating that the bimodal distribution of patch-occupancy frequencies can be generated by structurally more complex and more realistic metapopulation models than the original one; that the bimodal distribution is predicted by deterministic models, with no or infrequent switches of species between the core and the satellite state; and that metapopulation extinctions of rare species may be compensated by migration from outside the metapopulation (from a mainland), or metapopulation extinction may be prevented by low extinction probabilities of local populations in large or high-quality habitat patches. In every case the bimodal core-satellite distribution is due to the rescue effect, that is, the increasing migration rate and hence the decreasing probability of local extinction with an increasing fraction of patches occupied. We discuss how the metapopulation dynamic mechanisms described in this article may generate the bimodal core-satellite distribution in different kinds of communities.
1. Dynamic Energy Budget (DEB) theory was designed to understand the dynamics of biological systems from cells to populations and ecosystems via a mass balance approach of individuals. However, most work so far has focused on the level of the individual. To encourage further use of DEB theory in a population context, we developed DEB-IBM, a generic individual-based model (IBM) that is based on DEB theory.
2. The generic IBM is implemented as a computer program using NetLogo, a free software platform that is accessible to biologists with little programming background. The IBM uses DEB to represent assimilation, maintenance, growth and reproduction of individuals. The model description follows the overview, design and details (ODD) protocol, a generic format for describing IBMs, and thereby provides a novel and accessible introduction to DEB theory and how it works in a population context.
3. Dynamic Energy Budget-individual-based model can be used to explore properties of both individual life-history traits and population dynamics, which emerge from the set of DEB parameters of a species, and their interaction with environmental variables such as food density. Furthermore, DEB-IBM can be adapted to address specific research questions, for example by including spatial effects. A user manual explains how this can be done.
4. Dynamic Energy Budget-individual-based model is designed to both facilitate use and testing DEB theory in a population context and to advance individual-based modelling by basing the representation of individuals on well-tested physiological principles.
Tolerance values for families of arthropods are presented to enable calculation of a family-level biotic index (FBI) in the field. In six streams differing in substrates and degree of organic pollution, an average of 23 min, 35 s was needed to assess the condition of a stream in the field using the FBI; this period was at least an hour less than is normally required to evaluate a stream with the generic- and species-level biotic index (BI). Comparison of the FBI and BI of replicated samples from these six streams and from 120 random samples from other Wisconsin streams showed that some accuracy is lost by using the FBI, with the FBI usually indicating greater pollution than the BI in unpolluted or slightly polluted streams and less pollution in polluted streams. The purpose of the FBI is to provide a rapid, but less critical, evaluation of streams in the field by biologists who can recognize arthropod families by sight. It is not intended as a substitute for the BI.
Contamination of soil with toxic heavy metals poses a major threat to the environment and human health. Anthropogenic sources include smelting of ores, municipal wastes, fertilizers, and pesticides. In assessing soil quality and the environmental and ecological risk of contamination with heavy metals, often homogeneous contamination of the soil is assumed. However, soils are very heterogeneous environments. Consequently, both contamination and the response of soil organisms can be assumed to be heterogeneous. This might have consequences for the exposure of soil organisms and for the extrapolation of risk from the individual to the population level. Therefore, to explore how soil contamination of different spatial heterogeneity affects population dynamics of soil invertebrates, we developed a spatially explicit individual-based model of the springtail, Folsomia candida, a standard test species for ecotoxicological risk assessment. In the model, individuals were assumed to sense and avoid contaminated habitat with a certain probability that depends on contamination level. Avoidance of contaminated areas thus influenced the individuals' movement and feeding, their exposure, and in turn all other biological processes underlying population dynamics. Model rules and parameters were based on data from the literature, or were determined via pattern-oriented modelling. The model correctly predicted several patterns that were not used for model design and calibration. Simulation results showed that the ability of the individuals to detect and avoid the toxicant, combined with the presence of clean habitat patches which act as "refuges", made equilibrium population size due to toxic effects less sensitive to increases in toxicant concentration. Additionally, the level of heterogeneity among patches of soil (i.e. the difference in concentration) was important: at the same average concentration, a homogeneously contaminated scenario was the least favourable habitat, while higher levels of heterogeneity corresponded to higher population growth rate and equilibrium size. Our model can thus be used as a tool for extrapolating from short-term effects at the individual level to long-term effects at the population level under more realistic conditions. It can thus be used to develop and extrapolate from standard ecotoxicological tests in the laboratory to ecological risk assessments.
The need for cost-effective risk assessment of chemicals is leading to the development of a reductionist paradigm that tries to assess impacts on humans and ecosystems from molecular changes. However, the biggest challenge for this paradigm comes from the emergence of properties that arise out of the interactions of the parts that are not included and yet which are key for assessing likely impacts. Although identifying key events and adverse outcome pathways can shed light on the involvement of important metabolic processes in toxicity, this does not mean that particular molecular initiating events are likely to be robust or accurate predictors of impacts that matter. There are even greater challenges for the new paradigm applied to ecological systems than to human health because of the need to link across more levels of biological organization. The present study argues for a predictive systems approach that makes the linkages through systems models in a mechanistic way that allows for emergence and that also has the potential for reducing the costs and use of animals in ecological risk assessments. Environ. Toxicol. Chem. 2012; 31: 2663-2671. © 2012 SETAC.
Traditional approaches to ecotoxicology and ecological risk assessment frequently have ignored the complexities arising due to the spatial heterogeneity of natural systems. In recent years, however, ecologists have become increasingly aware of the influence of spatial organization on ecological processes. Landscape ecology provides a conceptual and theoretical framework for the analysis of spatial patterns, the characterization of spatial aspects of ecosystem function, and the understanding of landscape dynamics. Incorporating the insights of landscape ecology into ecotoxicology will enhance our ability to understand and ultimately predict the effects of toxic substances in ecological systems. Ecological risk assessments need to explicitly consider multiple spatial scales, accounting for heterogeneity within contaminated areas and for the larger landscape context. A simple simulation model is presented to illustrate the effects of spatial heterogeneity by linking an individual-based toxicokinetic model with a spatially distributed metapopulation model. Dispersal of organisms between contaminated and uncontaminated patches creates a situation where risk analysis must consider a spatial extent broader than the toxicant-contaminated area. In general, the addition of a toxicant to a source patch (i.e., a net exporter of individuals) will have a greater impact than the same toxicant addition to a sink patch (i.e., a net importer of individuals).
Climate change models predict an increase in the frequency and intensity of extreme fluctuations in water level in aquatic habitats. Therefore, it is necessary to understand the combined effects of hydrological fluctuations and toxicants on aquatic biological communities. We investigated the individual and combined effects of the insecticide esfenvalerate and recurring fluctuations in water level on zooplankton communities in a system of 55 outdoor pond microcosms. The communities were exposed to esfenvalerate contamination as a single pulse (at 0.03, 0.3, or 3μg/L) and gradual removal of water and its subsequent replacement over three cycles and monitored until 84 days after contamination. The results showed that the sensitivities of the community and its constituent populations to the toxicant were increased by the hydrological stress. Specifically, for both the community structure and abundance of Daphnia spp. the lowest-observed-effect concentrations (LOEC) were 0.03 and 0.3μg/L for the series with fluctuating and constant water levels, respectively. Despite these differences in sensitivity, the interactive effects of the two stressors were found to be additive for both the community structure and the abundance of the most affected species. Presumably, it was not possible to detect synergism due to the strong individual effects of the water level fluctuations. Recovery times in the series exposed to the highest pesticide concentration were 64 and 55 days under fluctuating and constant water level regimes, respectively. Competition and water quality are suggested to be the major factors that underlie the observed effects of fluctuations in the water level. For the ecological risk assessment of toxicants, the present results suggest that (i) community sensitivity may vary substantially, depending on the environmental context, and (ii) this variability can be assessed experimentally to derive safety factors (coefficients used to avoid unexpected effects and define safe concentrations of toxicants) based on empirical findings. This contrasts with the current approach where such factors are usually defined arbitrarily.
Models are used to investigate the impact of pesticides on invertebrate predator-prey densities.
1. Applications of graph-theoretic connectivity are increasing at an exponential rate in ecology and conservation. Here, limitations of these measures are summarized.
2. Graph-theoretic connectivity measures are fundamentally limited as they require specification of a habitat quality threshold to allow definition of habitat patches (nodes). Frequently, a second threshold (critical dispersal distance) is applied in the identification of graph edges.
3. Graph-theoretic measures are poorly applicable to large-scale, high-resolution, grid-based data that describe distributions of species in habitats of varying quality.
4. Graph-theoretic connectivity primarily concerns the emigration-immigration component of spatial population-dynamics. Therefore, it cannot alone answer questions about the regional population size, resilience or persistence of a focal species.
5.Synthesis and applications: Conservation managers in particular should appreciate these limitations before applying graph-theoretic analysis to spatial conservation planning.
1. Many species are adapted to landscapes with characteristic dynamics generated by ongoing habitat destruction and creation. Climate change and human land use, however, may change the dynamics of these landscapes. Studies have repeatedly shown that many species are not able to cope with such changes in landscape dynamics. Conservation policies must, therefore, explicitly address this threat. The way in which management should be modified when formerly static landscapes become dynamic or when landscape dynamics change is unclear.
We report on the advantages and problems of using toxicokinetic-toxicodynamic (TKTD) models for the analysis, understanding, and simulation of sublethal effects. Only a few toxicodynamic approaches for sublethal effects are available. These differ in their effect mechanism and emphasis on linkages between endpoints. We discuss how the distinction between quantal and graded endpoints and the type of linkage between endpoints can guide model design and selection. Strengths and limitations of two main approaches and possible ways forward are outlined. Environ. Toxicol. Chem. 2011;30:2519–2524. © 2011 SETAC
1. The use of species traits to interpret biological changes in invertebrate assemblages across environmental gradients has been suggested as a method to improve discrimination over existing species composition methods. One reason for greater potential discrimination and predictive ability is the assumed universality of traits across a range of spatial and temporal scales. We explore this assumption by comparing the consistency of stressor–response relationships of a trait characteristic (percent clinging taxa) and a common taxonomy-based metric [percent Ephemeroptera, Plecoptera and Trichoptera (EPT)] over a stressor gradient of increasing benthic fine sediment.
2. We use invertebrate assemblage and environmental data from three large-scale surveys that cover the western United States, eastern United States and the Mid-Atlantic Highlands of the US. These three datasets allow us to compare stressor–response relationships in terms of geographic position (west versus east) and spatial scale (entire east versus a sub-region of the east). We compare the slopes and intercepts of the two measures of assemblage response.
3. Trait characteristics exhibited more consistent stressor–response relationships than identity characteristics. Stressor–response relationships generated for clinging invertebrate richness had statistically similar slopes over sediment gradients, regardless of spatial scale or geographic location. In contrast, slopes were significantly different for relationships generated with EPT richness over sediment gradients.
4. Results of this study support the hypothesis that trait-based measures have a more consistent response to a stressor gradient than identity-based assemblage measures. Choosing consistent measures of community response will facilitate comparisons among assemblages across large spatial scales.
