The UGent Environmental Toxicology Research Group aims to advance the understanding of ecotoxicological problems at different levels of biological organisation, in order to improve environmentally relevant ecological risk assessment and support sustainable development.
With our research we aim to address the ‘extrapolation problems’ - in the aquatic environment sensu lato - one encounters when assessing ecological risk based on results from laboratory bioassays with single species. The bulk of the available bioassays typically consider effects of aqueous exposure of single data-rich stressors on one generation of one well-characterized species in a standardized test medium. In reality, however, subsequent generations of field populations are exposed via various uptake routes to complex mixtures of multiple (emerging and thus data-scarce) stressors, potentially exerting (toxic) stress constrained by their bioavailability in the natural water body. Unlike the organisms used in laboratory tests, exposed individuals may have different genetic architecture even when belonging to the same species. Lastly, species do not live in isolation, as is the case in single-species toxicity bioassays, but take part in natural food webs to sustain ecosystem functions and services.
OECD publishes guidance document on developing and assessing Adverse Outcome Pathways
Recently, the Organisation for Economic Co-operation and Development (OECD) published a guidance document (No 184) on developing and assessing Adverse Outcome Pathways (AOP). The AOP methodology is an approach which provides a framework to collect, organise and evaluate relevant information on chemical, biological and toxicological effect of chemicals. This approach supports the use of a mode (and/or mechanism) of action basis for understanding adverse effects of chemicals. Our research contributes to this methodology by studying gene-expression patterns in response to toxicants (e.g. Asselman et al. 2012, Vandegehuchte et al. 2010) to extrapolate effects at the molecular level to effects at the organismal level. In addition, our population and ecosystem models (e.g. De Laender et al. 2011, Viaene et al. 2013) allow to extrapolate from this organismal level to even higher levels of organisation as the population or ecosystem. Not only contributes our research to the AOP methodology, it also benefits from it as the AOP for a marine natural toxin, domoic acid, to which we also perform research, is known.
Added: May 17th, 2013; 3:17 PM
Prof. Karel De Schamphelaere on the impact of acrylonitrile on the environment
(06-05-2013) A few days ago, the toxic substance acrylonitrile was released into the environment following a major train accident in Wetteren, Belgium. Today, prof. Karel De Schamphelaere was interviewed by the national news channel about the consequences of acrylonitrile on the environment. (Dutch spoken)
© 2013; courtesy of VRT Nieuws (Flanders News)
LMAE at SETAC Europe
(06-05-2013) The research group Environmental Toxicology will be presenting its research at the 23rd SETAC Europe Annual Meeting in Glasgow, UK from 12-16 May 2013. We will highlight our reserach in a total of four platforms, one poster corner and nine posters. To keep track of us during the conference, to download posters or to read more information, go to our dedicated SETAC webpage.
LMAE at PRIMO
(03-05-2013) Our lab will be represented at the 17th PRIMO meeting (Pollutant Responses In Marine Organisms), 5th - 8th May 2013 in Faro, Portugal. More information can be found at the conference website: http://www.cima.ualg.pt/primo17/. There will be three posters and one platform presentation.
Emerging contaminants in Belgian marine waters: Single toxicant and mixture risks of pharmaceuticals
(03-05-2013) Knowledge on the effects of pharmaceuticals on aquatic marine ecosystems is limited. The aim of this study was therefore to establish the effect thresholds of pharmaceutical compounds occurring in the Belgian marine environment for the marine diatom Phaeodactylum tricornutum, and subsequently perform an environmental risk assessment for these substances. Additionally, a screening-level risk assessment was performed for the pharmaceutical mixtures.
No immediate risk for acute toxic effects of these compounds on P. tricornutum were apparent at the concentrations observed in the Belgian marine environment. In two Belgian coastal harbours however, a potential chronic risk was observed for the ?-blocker propranolol. No additional risks arising from the exposure to mixtures of pharmaceuticals present in the sampling area could be detected. However, as risk characterization ratios for mixtures of up to 0.5 were observed, mixture effects could emerge should more compounds be taken into account.
Full reference (link)
Claessens M, Vanhaecke L, Wille K, Janssen CR. 2013. Emerging contaminants in Belgian marine waters: Single toxicant and mixture risks of pharmaceuticals. Marine Pollution Bulletin. In press.
Cloning and functional analysis of the ecdysteroid receptor complex in the opossum shrimp Neomysis integer (Leach, 1814)
(26-04-2013) In this paper, the non-target effects of tebufenozide were evaluated on the estuarine crustacean, the opposum shrimp Neomysis integer (Leach, 1814). Tebufenozide is a synthetic non-steroidal ecdysone agonist insecticide and regarded as potential endocrine-disrupting chemical (EDC). N. integer is the most used crustacean in ecotoxicological research in parallel to Daphnia sp. and has been proposed for the regulatory testing of potential EDCs in the US, Europe and Japan.
Major results were: (i) cDNAs encoding the ecdysteroid receptor (EcR) and the retinoid-X-receptor (RXR), were cloned and sequenced, and subsequent molecular phylogenetic analysis (maximum likelihood and neighbor-joining) revealed that the amino acid sequence of the ligand binding domain (LBD) of N. integer EcR (NiEcR) clusters as an outgroup of the Crustacea, while NiRXR-LBD clusters in the Malacostracan clade (bootstrap percentage = 75%). (ii) 3D-modeling of ligand binding to NiEcR-LBD demonstrated an incompatibility of the insecticide tebufenozide to fit into the NiEcR-ligand binding pocket. This was in great contrast to ponasterone A (PonA) that is the natural molting hormone in Crustacea and for which efficient docking was demonstrated. In addition, the heterodimerization of NiEcR-LBD with the common shrimp Crangon crangon (Linnaeus, 1758) RXR-LBD (CrcRXR-LBD) was also modeled in silico. (iii) With use of insect Hi5 cells, chimeric constructs of NiEcR-LBD and CrcRXR-LBD fused to either the yeast Gal4-DNA binding domain (DBD) or Gal4-activation domain (AD) were cloned into expression plasmids and co-transfected with a Gal4 reporter to quantify the protein–protein interactions of NiEcR-LBD with CrcRXR-LBD. Investigation of the ligand effect of PonA and tebufenozide revealed that only the presence of PonA could induce dimerization of this heterologous receptor complex. (iv) Finally, in an in vivo toxicity assay, N. integer juveniles were exposed to tebufenozide at a concentration of 100 μg/L, and no effects against the molting process and nymphal development were scored.
In conclusion, the in vitro cell reporter assay, based on NiEcR-LBD/CrcRXR-LBD heterodimerization in Hi5 cells and validated with the natural ecdysteroid hormone PonA, represents a useful tool for the screening of putative EDCs. As a test example for non-steroidal ecdysone agonist insecticides, tebufenozide had no negative effects on NiEcR/RXR receptor dimerization in vitro, nor on the molting process and nymphal development of N. integer at the tested concentration (100 μg/L) in vivo.
Full reference (link)
De Wilde R, Swevers L, Soina T, Christiaens O, Rougé P, Cooreman K, Janssen CR, Smagghe G. 2013. Cloning and functional analysis of the ecdysteroid receptor complex in the opossum shrimp Neomysis integer (Leach, 1814). Aquatic Toxicology 130–131:31–40.
Modelling the effects of copper on soil organisms and processes using the free ion approach: Towards a multi-species toxicity model
(24-04-2013) Our lab has a long history of metal bioavailability research. Here, the results of previous terrestrial studies performed by our lab was used and integrated with other datasets to develop a general biovailability model for copper. The free ion approach has been previously used to calculate critical limit concentrations for soil metals based on point estimates of toxicity. In this study, the approach was applied to dose–response data for copper effects on seven biological endpoints in each of 19 European soils. The approach was applied using the concept of an effective dose, comprising a function of the concentrations of free copper and 'protective' major cations, including H+. A significant influence of H+ on the toxicity of Cu2+ was found, while the effects of other cations were inconsistent. The model could be generalised by forcing the effect of H+ and the slope of the dose–response relationship to be equal for all endpoints. This suggests the possibility of a general bioavailability model for copper effects on organisms. Furthermore, the possibility of such a model could be explored for other cationic metals such as nickel, zinc, cadmium and lead.
Full reference (link)
Lofts S, Criel P, Janssen CR, Lock K, McGrath SP, Oorts K, Rooney CP, Smolders E, Spurgeon DJ, Svendsen C, Van Eeckhout H, Zhao F-Z. 2013. Modelling the effects of copper on soil organisms and processes using the free ion approach: Towards a multi-species toxicity model. Environmental Pollution 178:244–253.
New techniques for the detection of microplastics in sediments and field collected organisms
(18-04-2013) Microplastics have been reported in marine environments worldwide. Accurate assessment of quantity and type is therefore needed. Here, we propose new techniques for extracting microplastics from sediment and invertebrate tissue. The method developed for sediments involves a volume reduction of the sample by elutriation, followed by density separation using a high density NaI solution. Comparison of this methods' efficiency to that of a widely used technique indicated that the new method has a considerably higher extraction efficiency. For fibres and granules an increase of 23% and 39% was noted, extraction efficiency of PVC increased by 100%. The second method aimed at extracting microplastics from animal tissues based on chemical digestion. Extraction of microspheres yielded high efficiencies (94–98%). For fibres, efficiencies were highly variable (0–98%), depending on polymer type. The use of these two techniques will result in a more complete assessment of marine microplastic concentrations.
Full reference (link)
Claessens M, Van Cauwenberghe L, Vandegehuchte M, Janssen CR. 2013. New techniques for the detection of microplastics in sediments and field collected organisms. Marine Pollution Bulletin, In press.
SCIENTIFIC COMMITTEE ON HEALTH AND ENVIRONMENTAL RISKS
Prof. Janssen elected Chair of EU Committee SCHER
(15-04-2013) On 11 and 12 April 2013, the first meeting of the newly appointed EU Scientific Committee SCHER took place in Luxembourg. After a rigorous selection procedure - i.e. there were more than 400 candidates - based on criteria such as scientific excellence and independence, Prof. Janssen was appointed as one of the 11 members of SCHER (Scientific Committee on Health and Environmental Risks). Committee members are appointed for a three-year term and will provide the Commission with independent scientific advice on issues relating to consumer safety, public health and the environment. Following his appointment Prof. Janssen was then elected by SCHER members to serve as Chair of the Committee.
More information on SCHER and the inaugural meeting: http://ec.europa.eu/health/scientific_committees/events/ev_20130411_en.htm#pics.
RESEARCH IN THE SPOTLIGHT
North Sea full of plastic
(13-04-2013) As announced earlier (see news announcement of 08-04-2013), Prof. Janssen and Lisbeth spent a whole day with a VRT camera crew (Flemish television channel) on board the research vessel Simon Stevin to present our research concerning the occurrence and effects of (micro-)plastics in the North Sea. Last week this topic was extensively covered on the national news channels and the TV program 'Koppen'.
© 2013; courtesy of VRT Nieuws (Flanders News).
More reportages can be found at:
Monitoring micropollutants in marine waters, can quality standards be met?
(10-04-2013) The environmental risks of 33 micropollutants occurring in Belgian coastal zone were assessed as single substances and as mixtures. Water and sediment samples were taken in harbors, coastal waters and the Scheldt estuary during 2007–2009. Measured environmental concentrations were compared to quality standards such as Predicted No Effect Concentrations (PNECs), Environmental Quality Standards (EQSs), and Ecotoxicological Assessment Criteria (EAC). Out of a total of 2547 samples analyzed, 232 and 126 samples exceeded the EQS and EAC, respectively. Highest risks were observed for TBT, PBDEs, PCBs and the PAHs anthracene, indeno(1,2,3-cd)pyrene, benzo(g,h,i)perylene, benzo(k)fluoranthene, and benzo(b)fluoranthene in the water compartment and for TBT and PCBs in the sediment compartment. Samples taken at all stations during the April 2008 campaign indicate a potential risk of the contaminant mixtures to the aquatic environment (except W06 station). This study argues the need to revise quality standards when appropriate and hence the overall regulatory implication of these standards.
Full reference (link)
Ghekiere A, Verdonck F, Claessens M, Monteyne E, Roose P, Wille K, Goffin A, Rappé K, Janssen CR. 2013. Monitoring micropollutants in marine waters, can quality standards be met? Marine Pollution Bulletin 69:243-250.
RESEARCH IN THE SPOTLIGHT
Camera crew films our micro-plastics research aboard research vessel
(08-04-2013) Last week Prof. Janssen and Lisbeth spent a whole day with a VRT camera crew (Flemish television channel) on board the research vessel Simon Stevin. Our research concerning the occurrence and effects of (micro-)plastics will be extensively covered during the Koppen program which will be broadcast next Thursday (11-4) at 8.35 pm on Eén. Below some tastemakers:
Application of a silicone rubber passive sampling technique for monitoring PAHs and PCBs at three Belgian coastal harbours
(27-03-2013) A 4-year monitoring study - coordinated by our lab - was performed to examine the freely dissolved water concentrations of PAHs and PCBs in three coastal harbours and at an offshore station in the North Sea. The results are part of a more extensive study to provide information on occurrence, distribution and effects of pollutants in the Belgian coastal zone. In the present study silicone rubber passive samplers were used. We found that the non-linear least-square (NLS) method proved to be suitable for estimating sampling rates when using the following performance reference compounds: fluorene-d10, phenanthrene-d10, fluoranthene-d10, benzo(e)pyrened12, coronene-d12, CB10, CB14, CB50, CB104, CB145 and CB204. The application of two NLS methods for estimating the sampling rate (Rs) resulted in significant differences for freely dissolved concentrations for individual compounds of up to 30% between the two methods. A model that takes into account the decrease of sampling rate for compounds with higher molecular weight should give a more accurate Rs and was the preferred estimation method. Rs varied from 0.9 to 34.8 L/d for the different target compounds, while estimated freely dissolved concentrations for sum 15 PAHs varied between 3.9 and170 ng/L and for sum 14 PCBs between 0.030 and 3.1 ng/L. The stations located within marinas showed the highest level of contamination, while the offshore station (5 mile from coastline) exhibited the lowest level. The implications of the use of passive samplers for monitoring programs are discussed.
Full reference (link)
Monteyne E, Roose R, Janssen CR. 2013. Application of a silicone rubber passive sampling technique for monitoring PAHs and PCBs at three Belgian coastal harbours. Chemosphere 91:390-398.
Whole sediment toxicity tests for metal risk assessments: On the importance of equilibration and test design to increase ecological relevance.
(20-03-2013) Current laboratory-based approaches for predicting metal toxicity in sediments exhibit a number of limitations. The most important are (1) a lack of sufficient equilibration resulting in unrealistically low pH values or unnaturally high pore water metal concentrations and (2) an inadequate test design regarding the metal concentrations selected for spiking. This study illustrates that by explicitly accounting for these limitations, one obtains reliable and environmentally realistic toxicity data, thus advancing the metal risk assessments of sediments. To this end, a toxicity test design with natural sediments was developed in which the administered metal concentrations were selected to comprise a range of [SEM-AVS] (the difference between the molar concentration of simultaneously extracted metals and acid volatile sulfides) closely surrounding zero. In addition, the presented test design includes a 35 or 40 day equilibration period with overlying water renewal during which conductivity, pH and metal concentrations in the overlying water are monitored. This allows toxicity testing to start after equilibrium for these parameters has been reached. This test design was applied to Ephoron virgo (Olivier, 1791), Gammarus pulex (Linnaeus, 1758) and Lumbriculus variegatus (Mueller, 1774) exposed to Zn and Pb. These tests indicated that the general concept of absence of toxicity when [SEM-AVS]<0 could not be rejected. However, the onset of Zn toxicity occurred at lower concentrations than generally assumed.
Full reference (link)
Vandegehuchte MB, Nguyen LTH, De Laender F, Muyssen BTA, Janssen CR. 2013. Whole sediment toxicity tests for metal risk assessments: On the importance of equilibration and test design to increase ecological relevance. Environmental Toxicology and Chemistry. Accepted. DOI: 10.1002/etc.2156.
A re-evaluation of fifteen years of European Risk Assessment using effect models
(19-03-2013) Ecological risk assessments of chemicals can be informed by a suite of effect models, including population and food web models. In the risk assessments conducted under EU regulation 793/93/EC, however, applications of such effect models are extremely scarce and toxicity-extrapolation approaches are often used instead. The objective of the present study was to re-evaluate these risk assessments using two types of effect models: species sensitivity distributions (SSDs, non-mechanistic), and food web models (mechanistic). Species sensitivity distributions significantly fitted the available toxicity data for up to 35% of the chemicals, depending on the trophic levels included and the amount of data available. Median hazardous concentrations for 5% of the species (HC5-50) estimated by the SSDs were less accurate predictors of measured community-level no observed effect concentration than food web model-derived HC5-50s, albeit data were available for seven chemicals only. For datasets with more than 10 data points, the 90% confidence interval of the estimated HC5s was narrower for the food web modeling approach than for the SSD approach. The HC5-50s predicted by the two approaches were two to five times (metals) and 10 to 100 times (organic chemicals) higher than the predicted no effect concentrations (PNECs) for the aquatic environment listed in the risk assessment reports. This suggests that the derived PNECs are protective for aquatic ecosystems.
Full reference (link)
De Laender F, Van Sprang P, Janssen C. 2013. A re-evaluation of fifteen years of European Risk Assessment using effect models. Environmental Toxicology and Chemistry 32(3):594–601.
Using additive modelling to quantify the effect of chemicals on phytoplankton diversity and biomass
(14-03-2013) Environmental authorities require the protection of biodiversity and other ecosystem properties such as biomass production. However, the endpoints listed in available ecotoxicological datasets generally do not contain these two ecosystem descriptors. Inferring the effects of chemicals on such descriptors from micro- or mesocosm experiments is often hampered by inherent differences in the initial biodiversity levels between experimental units or by delayed community responses. Here we introduce additive modelling to establish the effects of a chronic application of the herbicide linuron on 10 biodiversity indices and phytoplankton biomass in microcosms. We found that communities with a low (high) initial biodiversity subsequently became more (less) diverse, indicating an equilibrium biodiversity status in the communities considered here. Linuron adversely affected richness and evenness while dominance increased but no biodiversity indices were different from the control treatment at linuron concentrations below 2.4 μg/L. Richness-related indices changed at lower linuron concentrations (effects noticeable from 2.4 μg/L) than other biodiversity indices (effects noticeable from 14.4 μg/L) and, in contrast to the other indices, showed no signs of recovery following chronic exposure. Phytoplankton biomass was unaffected by linuron due to functional redundancy within the phytoplankton community. Comparing thresholds for biodiversity with conventional toxicity test results showed that standard ecological risk assessments also protect biodiversity in the case of linuron.
Full reference (link)
Viaene K, De Laender F, Van den Brink PJ, Janssen C. 2013. Using additive modelling to quantify the effect of chemicals on phytoplankton diversity and biomass Science of the Total Environment 449:71-80.
Dr. ir. Frederik De Laender joined the Young Academy
(13-02-2013) Recently, the Royal Flemish Academy of Belgium decided to establish a Young Academy. Forty young researchers, amongst whom Frederik De Laender of our lab, have joined the Young Academy. They were selected from as many as 146 high-potential candidates who responded to the call for membership. These young researchers have three objectives: (international) interdisciplinary research, reflection about the current science policy, and science communication to the youth. Congratulations, Frederik!
Update: In total 13 researchers of Ghent University were selected. More information: http://www.ugent.be/nl/actueel/nieuws/ugent-jonge-academie.htm (Dutch)
Best oral presentation award on the 18th national symposium on applied biological sciences
(12-02-2013) A few days ago, the 18th National Symposium on Applied Biological Sciences took place in Ghent at which we were present with four oral presentations and four poster presentations. It was a successful symposium, not the least for our lab-member David Deruytter who won the award for best oral presentation in the Environmental Quality session with his talk entitled "The combined effect of DOC and salinity on the accumulation and toxicity of copper in mussel larvae". Congratulations, David!
Interactive effects of a bacterial parasite and the insecticide carbaryl to life-history and physiology of two Daphnia magna clones differing in carbaryl sensitivity
(12-02-2013) Natural and chemical stressors occur simultaneously in the aquatic environment. Their combined effects on biota are usually difficult to predict from their individual effects due to interactions between the different stressors. Several recent studies have suggested that synergistic effects of multiple stressors on organisms may be more common at high compared to low overall levels of stress. In this study, we used a three-way full factorial design to investigate whether interactive effects between a natural stressor, the bacterial parasite Pasteuria ramosa, and a chemical stressor, the insecticide carbaryl, were different between two genetically distinct clones of Daphnia magna that strongly differ in their sensitivity to carbaryl. Interactive effects on various life-history and physiological endpoints were assessed as significant deviations from the reference Independent Action (IA) model, which was implemented by testing the significance of the two-way carbaryl × parasite interaction term in two-way ANOVA's on log-transformed observational data for each clone separately. Interactive effects (and thus significant deviations from IA) were detected in both the carbaryl-sensitive clone (on survival, early reproduction and growth) and in the non-sensitive clone (on growth, electron transport activity and prophenoloxidase activity). No interactions were found for maturation rate, filtration rate, and energy reserve fractions (carbohydrate, protein, lipid). Furthermore, only antagonistic interactions were detected in the non-sensitive clone, while only synergistic interactions were observed in the carbaryl sensitive clone. Our data clearly show that there are genetically determined differences in the interactive effects following combined exposure to carbaryl and Pasteuria in D. magna.
Full reference (link)
De Coninck DIM, De Schamphelaere KAC, Jansen M, De Meester L, Janssen CR. 2013. Interactive effects of a bacterial parasite and the insecticide carbaryl to life-history and physiology of two Daphnia magna clones differing in carbaryl sensitivity. Aquatic Toxicology 130-131: 149-159.
Master dissertation subjects available
(04-02-2013) Recently some new Master dissertation subjects have been added to the website http://fbwsrv02.ugent.be/masterproef/nl/onderwerpen, for students wanting to make their Bioscience Engineering Master dissertation in our research group. The following topics can now be chosen:
Check out our project websites
Combined and interactive effects of global climate change and toxicants on populations and communities
(02-01-2013) Increased temperature and other environmental effects of global climate change (GCC) have documented impacts on manyspecies (e.g., polar bears, amphibians, coral reefs) as well as on ecosystem processes and species interactions (e.g., the timing of predator–prey interactions). A challenge for ecotoxicologists is to predict how joint effects of climatic stress and toxicants measured at the individual level (e.g., reduced survival and reproduction) will be manifested at the population level (e.g., population growth rate, extinction risk) and community level (e.g., species richness, food-web structure). The authors discuss how population- and community-level responses to toxicants under GCC are likely to be influenced by various ecological mechanisms. Stress due to GCC may reduce the potential for resistance to and recovery from toxicant exposure. Long-term toxicant exposure can result in acquired tolerance to this stressor at the population or community level, but an associated cost of tolerance may be the reduced potential for tolerance to subsequent climatic stress (or vice versa). Moreover, GCC can induce large-scale shifts in community composition, which may affect the vulnerability of communities to other stressors. Ecological modeling based on species traits (representing life-history traits, population vulnerability, sensitivity to toxicants, and sensitivity to climate change) can be a promising approach for predicting combined impacts of GCC and toxicants on populations and communities.
Full reference (link)
Moe SJ, De Schamphelaere K, Clements WH, Sorensen MT, Van den Brink PJ, Liess M. 2013. Combined and interactive effects of global climate change and toxicants on populations and communities. Environ Tox Chem 32(1): 49-61.