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Aquatic and Terrestrial Ecotoxicology Session Summaries from SETAC Barcelona

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  • Advances and Criticalities of Sub-individual Approaches in Ecological Risk Assessment: The Way Forward
    • Claudia Vaj (Dow AgroSciences) and Marco Vighi (University of Milano Bicocca)

      Sub-individual endpoints have been widely used in ecotoxicology since the late 1970s as indicators of exposure and effect to toxicants. Recently, the approach was supported by the development of new methods such as proteomics and genomics. The success of these methods is mainly due to the need for early warning indicators of effects of dangerous chemicals, measurable with relatively easy procedures, in short time, in laboratory and in the field. However, the usefulness of subcellular endpoints in ecological risk assessment and their ability to provide unambiguous and ecologically relevant information on exposure to or effects of toxicants remains highly controversial. The debate in the scientific community on the ecological relevance of sub-individual parameters has recently become heated. The major reasons include:

      1. The scarce information available on natural populations. In many instances, few species are used as representing a minimal portion of the complexity of biological communities, which does not allow defining a variability range of these parameters in relation to biological and environmental factors. Moreover, one of the major difficulties of field studies on biomarkers is the definition of a suitable “control,” which should determine a variability range in absence of any stress factors.
      2. The objective of ecotoxicology is the protection of the structure and functioning of biological communities and ecosystems. Therefore, ecologically relevant endpoints must provide information on the consequences likely to occur at the highest hierarchical levels of organization (populations and communities). At present, our knowledge on the relationships between effects measured at the cellular or sub-cellular level and the consequences at the community level are very poor.

      The objective of this session was to present the advances on the application of sub-individual approaches in ecotoxicology, focused on addressing the above mentioned issues.

      Six posters where presented in the poster corner session addressing the following issues:

      1. A biological process, which appears to be sensitive to contamination stress in Gammarus fossarum, the digestive capacity, can potentially provide information occurring at the population level. However, it is not representative of the biological diversity. Inter-population variability was assessed according to environmental parameters, and the potential consequences of defining reference and threshold values via one control population were discussed.
      2. The natural variability of the levels of biochemical biomarkers in freshwater macrobenthos in absence of anthropogenic stress factors. Biomarker responses were studied in different taxa, at different stages of the life cycle, in relation to environmental conditions in different sampling sites, and in different phases of the seasonal cycle.
      3. Potential of the biomarkers of the oxidative stress in fishes to anticipate effects at population level after an input from a burnt area. Biomarker responses of a fish species (Gambusia holbrooki) can be used as early-warning signals for exposure to polycyclic aromatic hydrocarbons (PAHs) and metals to assess wildfires impact on water courses.
      4. The link between exposure to contaminants and effects through the different biological levels cannot be described solely by a set of biomarkers. The combination of water physicochemical properties and metal concentration with the use of different biomarkers is alternatively proposed as an index for wild freshwater mussels.
      5. The possibility to use transcriptomic biomarkers in sediment-contact bioassays as a bridge from causes to effects. Studies using arsenic and cadmium were run on rice, seeking measurable dose-dependent changes on both macroscopic and transcriptomic level.
      6. Adaptation of organisms to a stressor generates energetic costs, and it is reflected in the alteration of selected sub-individual traits. A set of biological responses in freshwater organism Gammarus pulex was compared at the beginning and at the end of a long-term exposure to metals.

      Addressing the role, relevance and usefulness of sub-individual endpoints in ecological risk assessment is a key topic in modern ecotoxicology. The need for a better understanding of the impact of effects measured at the molecular or cellular level on ecologically relevant parameters has been recently highlighted in a document by the European Commission as one of the priorities for ecotoxicological research.  Such a challenging issue cannot be discussed in depth in the limited time set for poster corners, nevertheless, the selected posters highlighted a number of relevant points:

      1. The need to consider biological variability (determined by natural conditions or by adaptation processes)
      2. The need for linking biomarkers with population-level effects or other ecologically relevant endpoints
      3. The usefulness of biomarkers as early warning systems
      4. The need for considering several factors, together with biomarkers, for understanding the complexity of the responses

      In conclusion, the discussion highlighted that the potential usefulness of sub-individual approaches may be further investigated and implemented.  Research efforts must be focused to improve the ecologically relevant meaning of these approaches and to link molecular and cellular effects to the possible consequences at the higher hierarchical levels (populations, communities).

      Authors’ contact information: Vaj@dow.com and marco.vighi@unimib.it

  • Behavior Revised: Examining Behavioral Effects of Contaminants and Other Stressors in Aquatic Animals
    • Greg Pyle (University of Lethbridge), Bryan Brooks (Baylor University) and Alex Ford (University of Portsmouth)

      Animal behavior integrates local environmental conditions with the internal physiological condition of the animal. Observed differences from “normal” behavioral patterns can provide insights into sublethal toxicity that can ultimately lead to population-level or ecological effects. There has been a recent increase in research activity exploring contaminant effects on behavior in aquatic animals given the sensitivity of the responses and the ecological relevance of the effects. Computational advances have allowed for detailed behavioral analyses that can provide insight into contaminant-induced neurological or cognitive impairment. This session brought together researchers to discuss recent advances in the area of behavioral toxicology.

      The platform session was well attended, and the concurrent poster session consisted of 20 poster presentations that extended the scope of the overall topic. The presentations provided an interesting range of perspectives on behavioral toxicology, from a critical review of the current state of the literature by a governmental regulator to results from academic research. Combined, the platform and poster presentations provide a truly international perspective on behavioral toxicology with presentations from Australia, Brazil, Canada, Finland, Germany, Italy, Portugal, Spain, Sweden, Taiwan, United Kingdom and the United States. Behavioral effects were documented in a range of aquatic animals, including both invertebrates and vertebrates, after being exposed to metals, pharmaceuticals, insecticides, hormone mimics and a variety of waste waters or polycyclic aromatic hydrocarbons.

      The platform session began with Burt Shephard (United States Environmental Protection Agency) presenting a critical review of the behavioral toxicology literature with a view towards implementing behavioral endpoints into a regulatory framework. Current copper regulatory guidelines appear to protect against behavioral impairment. However, more work needs to be done to standardize behavioral testing protocols before behavior can be implemented in a regulatory arena. This review is currently being developed into a manuscript for submission later this year.

      The presentations that followed focused on single-contaminant exposures and their effects on behavior. Patricia Pereira (University of Aveiro) demonstrated that inorganic mercury accumulated in brain and eye tissue of white seabream after a 14-day exposure, which failed to depurate over the 28-day post-exposure. These accumulation patterns were associated with impaired swim performance that persisted throughout the duration of the study. The following two presentations focused on the effects of pharmaceuticals on mate selection and predator–prey interactions. In the first study, Patrick Tomkins (Monash University) showed that female guppies preferred male guppies that had no prior exposure to trenbolone, an androgenic steroid used to promote cattle growth, relative to exposed males. However, females exposed to trenbolone showed no preference for either exposed or unexposed males. Melanie Hedgespeth (Lund University) demonstrated that European perch (Perca fluviatilis) exposed to a selective seratonin reuptake inhibitor (SSRI) pharmaceutical, sertraline, showed a 60% reduction in feeding rates and an impaired ability to avoid predators. Taken together, the impaired ability to select high-condition mates in trenbolone-exposed guppies and the impaired feeding and predator-avoidance behaviors in sertraline-exposed perch, demonstrate that pharmaceuticals entering the environment from water treatment plants have the potential to induce maladaptive behavioral responses in resident biota. More work is required to understand whether or not contaminant pharmaceuticals occur in natural systems at high enough concentrations to induce these kinds of effects and to demonstrate the impact of any potential ecological effects.

      The final two presentations of the session looked at contaminants associated with oil and oil extraction processes on fish behavior. In the first of these studies, Paulo Carvalho (Federal University of Pernambuco) showed that a tropical estuarine guppy (Poecilia vivipara) developed a repetitive swimming behavior after being exposed to moderate concentrations of phenanthrene (a polycyclic aromatic hydrocarbon associated with oil). This patterned behavior intensified with increasing phenanthrene accumulation in fish tissues and led to impaired capture of prey. Keith Tierney (University of Alberta) focused on neurophysiological and behavioral effects in rainbow trout (Oncorhynchus mykiss) exposed to oil sands process-affected water (OSPW). This study demonstrated that fish can detect and avoid OSPW at relatively low concentrations. However, when the contaminant is unavoidable, OSPW impairs the fish’s ability to detect and respond to food cues and increases swimming activity, which may, in turn, increase the fish’s conspicuousness to predators. Treating the OSPW with ozone ameliorated some of these acute chemosensory and behavioral effects.

      Author’ Contact information: gregory.pyle@uleth.ca, Bryan_Brooks@baylor.edu and alex.ford@port.ac.uk

  • Fish Model Species in Environmental Toxicology
    • Jessica Legradi and Juliette Legler (VU University Amsterdam) and Eduarda Santos (University of Exeter)

      Fish models are used commonly in ecotoxicity testing to investigate the impact of chemicals on the aquatic environment. A range of OECD guidelines are available, which use different fish species and target different toxicological endpoints. These studies, however, are limited to relatively few species, but fish offer far greater utility for research, spanning basic developmental biology, neurobiology, endocrinology and immunology. The small size of some available fish species including the zebrafish (Danio rerio) or medaka (Oryzias latipes) and their robust nature makes them ideally suited for application in automated high throughput screens. Furthermore, early life stages of these species offer all the key attributes of a complex in vivo system (including metabolism), as well as attributes of in vitro assays, as tests can be carried out in multiwell plates formats with small sample volumes and run in comparatively short periods of time. These attributes make them well suited for ecotox testing of environmental extracts and in effect directed analysis (EDA) to detect unknown contaminants in environmental samples. Research on fish over the last decade has been greatly facilitated by the availability of sequenced genomes, which are available for over 12 species with more pending. This facility, together with advances in genetic and epigenetic studies, including gene knockout and transgenesis technologies, is greatly facilitating understanding of the molecular mechanisms of toxicology, and thereby helping to study and define adverse outcome pathways (AOPs).

      The fish models session attracted 53 platform and poster presentations discussing the use of a wide range of fish models to address environmental toxicology questions. Currently, the zebrafish is the most widely used fish model species in laboratory studies because of its practical advantages to conduct toxicological experiments. These include its well characterized development and reproduction, its rapid life cycle, and availability of genomics and genetic resources. This was reflected in the large proportion of presentations where zebrafish was used as a model organism, both during this session and across the meeting.  However, zebrafish may not be the most representative model for fish species commonly found in the aquatic environments of Europe and across the globe. Therefore, there is a need to expand environmental toxicology studies to other, more representative fish model systems. Presentations on the utility of the three-spined stickleback, and other environmentally relevant species, provided ways forward to bridge the gap between laboratory models and environmental reality. Data utilizing state-of-the-art technologies on genomics, proteomics, metabolomics and epigenetics were presented, advancing our understanding of mechanistic pathways of chemical toxicity.

      The challenges of analyzing and interpreting these datasets within the context of realistic environmental conditions is considerable but, in the long term, it will facilitate a better understanding of the mechanistic pathways resulting in adverse impacts at the individual and population levels. It was interesting to see that fish toxicology studies are moving forward from testing individual compounds within simple dose-response exposure scenarios, to more complex experiments that better represent the reality of environmental exposures. Influences of environmental factors, including changes in oxygen concentrations, were shown to alter the toxicological responses to a metal. The complexity of environmental mixtures and their effects are well known but generally poorly considered in laboratory studies. Examples of the complexity of the responses to environmental mixtures included datasets demonstrating that two major components of the contraceptive pill acted antagonistically and suppressed the endocrine disrupting potential of the individual compounds in three-spined sticklebacks. In-depth analysis using temporal and tissue-specific high resolution approaches provided new insights on thyroid disruption, reactive oxygen species formation, and the aryl hydrocarbon receptor cascade. Passive dosing, mimicking more realistic environmental exposures to individual compounds and their mixtures was discussed, and its applicability to determine the toxicity of environmental samples (including soils) were shown. In addition, fish embryos were shown to successfully guide chemical detection and identification in an effect-directed analysis.

      The outcomes of the session provide evidence for the wide use of the zebrafish as a model species, and their suitability to conduct high throughput toxicity screening, and mechanistic analysis of chemical effects, particularly during embryo development. There is a clear need to continue to develop other environmentally relevant fish models in order to better protect the fish populations in the natural environment.

      Author’s contact information: Jessica.Legradi@vu.nl

  • Evolutionary, Multigenerational and Epigenetic Effects of Pollutants: Scientific Support to Long-term ERA
    • Marie-Agnès Coutellec (INRA), Carlos Barata (CSIC), João Pestana (University of Aveiro) and Karel De Schamphelaere (University of Gent)

      Many organisms, populations and species are currently facing severe degradation of their environment due to global change. Human activities, among which the continuous release of potentially toxic substances into the environment, contribute significantly to this pervasive change. There is growing evidence that environmental change may affect organisms beyond exposed generations and trigger transgenerational responses as well as rapid micro-evolutionary processes. Furthermore, biological responses may also depend on population standing genetic variation and evolutionary history, and on phylogenetic constraints. Assessing pollutant-driven selection in the field is extremely difficult due to confounding factors that also shape the distribution of genetic diversity. More so if we acknowledge that inherited and usually reversible epigenetic changes are another important source of variation in populations that can in turn modify those same evolutionary processes. This explains why it is still so challenging to integrate evolutionary indicators into ecological risk assessment (ERA). Nevertheless, evidence for transgenerational and evolutionary impact of pollutants is accumulating across a diversity of systems, and this reality cannot be ignored in future assessment procedures. Current approaches in population genomics have increased the power to investigate adaptation at the molecular level, which have proven to be relevant, including in an ecotoxicological context. However, scientific findings, even if they are obtained from the most sophisticated approaches, still need to be tested for their relevance to ERA, which would ideally require a dialog from the early stages between scientists and stakeholders (see EVOGENERATE Work Group of the SETAC ERA Advisory Group). Therefore, it becomes urgent to acquire tools and methods to measure, anticipate and even predict transgenerational and evolutionary ecotoxicological effects, as well as to understand their consequences for ecosystems, including species distribution and persistence. These tools should provide scientific guidance to support optimized decision-making through a sustainable trade-off between human demand on, and conservation of, natural resources.

      Five presentations were delivered in this session.

      Detail of the Session Talks

      1. The molecular and genetic bases of evolved tolerance to cadmium was investigated in Daphnia, using a thoroughly designed population genomics approach. The study revealed exposure-induced alterations in the magnitude and distribution of gene copy number (CNV) in natural populations historically exposed to chemical stressors (industrial smelting). A prevalence of duplications was detected in the set of genes identified as adaptive genes, in consistency with a model of environmental adaptation via sub-functionalization or neo-functionalization after gene duplication. Importantly, the study also showed that selection may act on gene network interactions, through epistasis, rather than on a single gene basis. The potential application of this methodology to risk assessment was discussed.
      2. Correlational approaches were also presented in an attempt to link population genetic diversity and structure with evolved tolerance to toxicants:
        1. Influence of chronic exposure to low radiation levels on genetic diversity, cytogenetic integrity and reproductive performances in plant populations from the vicinity of Chernobyl. No evidence for evolved resistance was detected.
        2. In chironomids, evolved tolerance to metals in exposed populations did not correlate with genetic erosion at neutral markers. The occurrence of local adaptation despite low population genetic differentiation was addressed in the discussion. In a similar context, new genetic markers were isolated and characterized in worms to compare genetic parameters among metallicolous and reference populations. Population genetic divergence in copper tolerance was found significant in a freshwater snail, suggesting that species-level extrapolations from toxicity tests based on single lines or populations may be strongly biased.
      3. A gender-specific pattern of hypomethylation induced by depleted Uranium was reported in Danio rerio, specifically in male gonads. Ongoing investigations are performed to further test if these epigenetic changes can be transmitted through generations. Transgenerational effects of waste water treatment plants were observed in the rainbow darter.
      4. Multigenerational effects of pesticide carbendazim and of polluted field water were reported in Daphnia magna at several endpoints, including DNA damage. Likewise, various multigenerational effects of nanoparticles were assessed in Caenorhabditis elegans and could furthermore be linked to the direct transfer of particles through generations.
      5. Finally, the need for standardized protocols to address evolutionary or transgenerational effects of pollutants in a regulatory context motivated the development of a “Daphnia multigenerational test”, based on existing guidelines. As a preliminary stage, a protocol was evaluated using various chemicals and addressing the influence of the brood order (first to third) on multigeneration effects.

      Epigenetic inheritance is likely to play an important role in the response of clonal species to toxicants.

      1. In conclusion, these presentations collectively highlighted the need to explicitly address evolutionary and transgenerational impacts of pollutants in the estimation of the risk to natural populations. The coupling of population and functional genomics appears most promising in this respect, so as to reach beyond the stage of correlational observations and provide solid cause and effect relationships, as required for ecological risk assessment to be reliable.
      2. This session was sponsored by the EVOGENERATE working group of the SETA ERA Advisory Group, which also organized a special symposium on the same topics at the SETAC North America 35th Annual Meeting, which was held in 2014 in Vancouver, Canada, aimed at promoting a constructive tripartite discussion between academia, regulators and business on multigenerational effects of pollutants as emerging issues in ecotoxicology, risk assessment and management (see SETAC –Globe 2015, Vol 16, issue 1, Session summaries from SETAC Vancouver; see also platform presentation and debate audio recordings.) 
      3. Next sessions on the same topics are planned at the SETAC North America 36th Annual Meeting, which will be held from 1–5 November in Salt Lake City, Utah, and next year at the SETAC Europe 26th Annual Meeting, which will be held in Nantes, France, from 22–26 May 2016.

      Authors’ Contact Information: marie-agnes.coutellec@rennes.inra.fr, cbmqam@cid.csic.es, jpestana@ua.pt and karel.deschamphelaere@ugent.be

  • From Ecosystem Services to Risk Assessment for Aquatic and Terrestrial Plants
    • Lorraine Maltby (Sheffield University) and Véronique Poulsen (Anses)

      This session was organized jointly by SETAC’s Plants Advisory Group and Ecosystem Services Advisory Group and focused on plants as they play a major role in ecosystems and agro-ecosystems as primary producers.

      Ecosystem services are a key element that has to be taken into account in risk assessment for defining specific protection goals in the framework of pesticide uses. Several workshops have been organized in Europe and the US under the auspices of SETAC, focusing on non-target plants or addressing ecosystem services as a whole.

      In this context, several research laboratories work on non-target aquatic and terrestrial plants in order to develop study protocols on additional species, complete existing ones with the objective of addressing recovery for example, or explore modeling approaches. In addition, in the framework of the EFSA draft guidance document and the SETAC European workshop, reviews have been conducted to address concerns related to representativeness of current risk assessment for wild terrestrial species.

      A poster corner was organized where the following 7 posters were presented by their authors:

      1. Modeling the impact of herbicide exposure on the structure and composition of non-target terrestrial plant communities, Jette Reeg
      2. Further developments in the risk assessment of pesticides to non-target terrestrial plants, Maria Arena
      3. Ecosystem services, environmental stressors and decision making – results of a Global SETAC and ESA Pellston Workshop, Joke Van Wensem
      4. Ecosystem services for aquatic macrophytes: Linking ecology to risk assessment of chemicals, Gertie H.P. Arts
      5. Sensitivity of wild plant and crop species to plant protection products – Literature review and analysis for SETAC AG Plants, Heino Christl
      6. Exploring an ecosystem services framework for setting protection goals and the needs of chemical risk assessment: Outcomes from four chemical sector case studies, Stuart Marshall
      7. An ecosystem services approach to pesticide risk assessment and risk management of non-target terrestrial plants: Recommendations from a SETAC Europe workshop, Lorraine Maltby

      All these posters can be downloaded from the SETAC Plants Global Advisory Group webpage.

      Authors’ contact information: l.maltby@sheffield.ac.uk and veronique.poulsen@anses.fr

  • Periphyton Ecology and Ecotoxicology—How Much Complexity and Reproducibility are Required to Connect Both Perspectives?
    • Alexandra Kroll, (Eawag Dübendorf), Marianne Matzke (CEH), Helena Guasch (University of Girona) and Mechthild Schmitt-Jansen (UFZ)
    • The aim of this session was to bring together periphyton ecology and ecotoxicology to see what both disciplines can learn from each other and what is necessary to combine in order to better understand community processes and toxicity mechanisms associated with ecosystem impairment.

      Periphyton is an essential component of stream ecosystems, shows dynamic responses to stressors, and is commonly used as a community model to analyze and indicate effects of water quality and pollutants. Periphyton ecology is based on the community structure, uses species identification, fingerprinting and sequencing to describe its statuses, and recent developments focus on ecosystem functions and functional traits. Periphyton ecology is mostly studied in field approaches leading to a lower reproducibility. On the other hand, periphyton ecotoxicology uses model ecosystems to reduce complexity enabling a higher reproducibility. Typically, periphyton ecotoxicology employs classical descriptors of functions such as biomass, effects on photosynthesis, or the metabolic profile. Recent developments include extracellular chemistry or the 3D structure of the community.

      From all the presentations it became obvious that molecular techniques (e.g. sequencing, fingerprinting) are now well established but always used alongside of classical endpoints such as biomass, photosynthesis (e.g. determination of lead pigments) or species composition (by microscopy). Also the concept of pollution-induced community tolerance (PICT) is applied more widely.  It is accepted that we need to introduce more ecological realism into risk assessment strategies for chemical stressors and that this can only be done by applying community models and acknowledging the fact that chemicals rarely act alone but mostly in combination with other stressors. On the other hand, reproducibility and controlled studies are needed to infer mechanisms of action.

      We asked the presenters to answer the question from their point of view how much complexity and reproducibility is needed to connect both perspectives – periphyton ecology and ecotoxicology and the main messages can be summarized as follows:

      1. Toxicological observations should be put into a multi-stressor context (chemical, temperature, pH) and various temporal and spatial scales should be used.
      2. Chemical and physical parameters have to be measured and documented to make complex settings comparable.
      3. A high complexity is needed to understand effects of chemicals on ecosystems but that this complexity is difficult to reproduce. The general danger is that too much complexity limits the understanding of effects. However periphyton might be the perfect tool to elucidate the underlying processes as it is a ‘relatively simple’ model responding in short times and is linked to basic and important ecosystem functions and processes.
      4. These processes are the intersection linking periphyton composition, communities and ambient environments when being under pollutant stress.
      5. It is important to determine global patterns of response and to cover a wider range of case studies to account for spatio-temporal variability in biofilms.

      Asking the audience (by distributing blank cards to be filled) and the presenters for their opinions on the posed questions was a great success in the chairs’ eyes as it stimulated an overall discussion. We intend to keep this scheme for the next session to be submitted and will include the topic in the upcoming open periphyton workshop in spring 2016.

      Authors’ contact information: alexandra.kroll@eawag.ch, martzk@ceh.ac.uk, mechthild.schmitt@ufz.de and helena.guasch@udg.edu

  • Plastics in the Aquatic Environment: Mechanisms and Implications
    • Alber A. Koelmans and Ellen Besseling (Wageningen University and IMARES) and Won Joon Shim (Korea Insitute of Ocean Science and Technology and University of Science and Technology, Daejeon)

      In this session, twelve high-quality studies were presented, which indicates that the field of microplastic (MP) research is maturing. It was shown that plastic is accumulating in a 6th gyre, in the more remote Arctic Circle, i.e., the Barentz Sea, with similar particle types and concentrations as in the Pacific Gyre. As for inputs to freshwaters, two studies showed that waste water treatment plants are quite efficient in retaining MPs, with retention reported to be 93 and 98% respectively. Differences in monitoring techniques, such as plankton net versus manta trawl, appear to have an important effect on detection of particle numbers, sizes and shapes. It was found that atmospheric fallout may be a significant source of MP fibers, a source that to date largely has been overlooked.

      Increasingly, research has been shifting towards the freshwater environment, with a Swiss study showing MP being present in water, sediments, rivers and biota, for instance. Stormwater overflows provided high inputs of MPs to rivers. An intriguing question is to what extent degradation of MP leads to micro- or even nano-meter sized particles, a process that may be relevant to shed light on another question raised in recent literature, “Where is all the plastic?” Two innovative studies dealt with abrasion mimicking natural conditions and showed polymer-dependent formation of small particles down to submicron sizes with suspected underestimation of the smaller size classes. It was shown that the smallest particles were rapidly colonized by micro-algae, increasing their density, such that this may cause sedimentation of the agglomerates in the water column.

      The first ever interspecies comparison was provided, and it detailed how ingestion of MP by benthic invertebrates depends on MP concentration, size and invertebrate head capsule width; the latter acting as a “sieve,” explaining selective uptake, with important potential implications for effects. Similarly, for limnic zooplankton, 100 µm MP did not cause effects on daphnids, whereas 1 µm MPs showed progressive immobilization over days. Uptake and a wide range of effects of nanoplastics (NP) on brine shrimp, mussels and sea urchin were demonstrated, which implies that understanding formation, fate, bioavailability and effects of nano-sized polymers is increasingly important. Yet, there are numerous challenges in how to perform standardized tests with NPs, which aggregate and come in many forms and ways of functioning.

      Another intriguing process is the formation of expanded polystyrene (EPS) MPs by lugworms burrowing in EPS buoys. The EPS particle sizes correlated with the size of the worms, and hexabromocyclododecane (HBCD) present in the buoys was also found in the lugworms, although it was not yet clear whether the uptake was from the water, the ingested EPS or both. No negative effects of EPS uptake on the worms were observed. A report on a lab experiment showed how fish fed with polybrominated diphenyl ether (PBDE)-spiked MPs increased their body burden of PBDEs, as long as uncontaminated fish and water were used in the test, thus rendering MP ingestion as the only PBDE exposure pathway. Another experiment, which was performed under environmentally relevant conditions that accounted for all environmentally occurring pathways and that used environmentally realistic MP concentrations, showed that MP ingestion did not increase uptake of PCBs by lugworms.

      It was concluded from the sessions that testing with environmentally realistic exposure concentrations and conditions becomes increasingly relevant in order to provide a scientific basis for assessing the hazards of MPs. MPs will be on the agenda of next year’s SETAC Europe meeting in Nantes, France, and also will be the subject of a Special Issue of the SETAC journal Environmental Toxicology and Chemistry, coming soon!

      Authors’ contact information: bart.koelmans@wur.nl, ellen.besseling@wur.nl and wjshim@kiost.ac.kr

  • Systems Biology: Increasing the Capacity, Understanding Ecosystems and Response Mechanisms to Model Chemicals (Including Nanomaterials)
    • Mónica Amorim and Susana Gomes (University of Aveiro), Susana Cristobal (Linkoping University), Christian Huber (University of Salzburg), Martin Eriksson (Chalmers Technical University) and Mechthild Schmitt-Jansen (Helmholtz Center for Environmental Research-UFZ)

      This session had two slots of 6 talks each, with the first slot dedicated to how meta-omics approaches could explore ecosystem responses to environmental changes. The second slot featured studies integrating more levels of organization towards a systems biology approach. The session was very well attended with very few seats left in the room.

      The studies presented applied meta-genomic and meta-proteomic approaches in complex ecological systems like marine microcosms, soils and sediments. For example, meta-genomics were critically evaluated for the description of diversity and community composition estimates. It was also used to characterize microbial communities of contaminated sites to support bioremediation and to unravel the mechanisms of nanoparticle effects in bacteria.

      The contributions demonstrated that meta-omic techniques are now in a state of application to explore ecologically relevant effects in impacted systems. The session illustrated that meta-omic approaches could support the molecular mechanistic understanding of effects on a community level and therewith provide a potential link to the Advance Outcome Pathway (AOP) concept from an ecosystem perspective.

      The systems biology part of the session was comprised of talks ranging from individual test models (including cell models, Daphnia magna, Enchytraeus crypticus) “-omics” to comparative genomics, covering the mathematical aspects of network theory for analysis of complex data matrices. The integration of various “-omics” (e.g., proteomics and metabolomics) translated into AOPs and covered various environmental compartments (aquatic and terrestrial) and human health.

      To highlight this, mechanisms of toxicity were shown for various materials, including nanomaterials.

      Several studies showed oxidative stress, as well as cell death and cell proliferation, as a common response mechanism, being that different techniques (e.g., metabolomics, proteomics and transcriptomics) outlined the same affected pathways, i.e., consistency. Further, studies integrating various levels of effects (organism-cell-gene) were translated onto AOPs.  

      Authors’ contact information: mjamorim@ua.pt, susana.gomes@ua.pt, Susana.Cristobal@liu.se, c.huber@sbg.ac.at,  martin.eriksson@chalmers.se and Mechthild.Schmitt@ufz.de

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