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Published on March 27, 2013

Application of a silicone rubber passive sampling technique for monitoring PAHs and PCBs at three Belgian coastal harbours

chemosphereA 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.

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Published on March 20, 2013

Whole sediment toxicity tests for metal risk assessments: On the importance of equilibration and test design to increase ecological relevance

etc cover2Current 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.

Published on March 14, 2013

Using additive modelling to quantify the effect of chemicals on phytoplankton diversity and biomass

scitotenvEnvironmental 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.

Published on February 14, 2013

Dr. ir. Frederik De Laender joined the Young Academy

jongeacademie 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)

Published on February 13, 2013

Best oral presentation award on the 18th national symposium on applied biological sciences

awardA 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!

Published on February 12, 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 toxicologyNatural 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

Published on February 4, 2013

Master dissertation subjects available

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:

  • Pesticides in aquatic ecosystems – from patterns to predictionsBiodiversity vs. Chemodiversity – exploring a new ecotoxicological conceptBack to the future: paleo-ecotoxicology.
  • The role of algal toxins in host-microbial interactions in the development of a sustainable larviculture of mussels and brine shrimp
  • Microplastics in the marine environment
  • Samen sterker? Het effect van metaalmengsels op de garnaal
  • Metal toxicology in freshwater sediments: environmental and biological factors affecting the sensitivity of benthic invertebrates
  • Marine toxins in the Belgian coastal zone from microalgae
  • Microplastic vervuiling op stranden en rond koraalriffen in Kenia? Een blinde vlek
  • Is 1 + 1 steeds gelijk aan 2? Modelleren van interactiepatronen in toxische mengsels met behulp van biologische netwerken

Published on January 2, 2013

Combined and interactive effects of global climate change and toxicants on populations and communities

open access thumb medium100 100Increased temperature and other environmental effects of global climate change (GCC) have documented impacts on many species (e.g., polar bears, amphibians, coral reefs) as well as on ecosystem processes and species interactions (e.g., the timing of predator–prey interactions). A challenge for ecotoxicologists is to predict how joint effects of climatic stress and toxicants measured at the individual level (e.g., reduced survival and reproduction) will be manifested at the population level (e.g., population growth rate, extinction risk) and community level (e.g., species richness, food-web structure). The authors discuss how population- and community-level responses to toxicants under GCC are likely to be influenced by various ecological mechanisms. Stress due to GCC may reduce the potential for resistance to and recovery from toxicant exposure. Long-term toxicant exposure can result in acquired tolerance to this stressor at the population or community level, but an associated cost of tolerance may be the reduced potential for tolerance to subsequent climatic stress (or vice versa). Moreover, GCC can induce large-scale shifts in community composition, which may affect the vulnerability of communities to other stressors. Ecological modeling based on species traits (representing life-history traits, population vulnerability, sensitivity to toxicants, and sensitivity to climate change) can be a promising approach for predicting combined impacts of GCC and toxicants on populations and communities.

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Published on November 20, 2012

Check out our project websites

  •  Aquastress

    The AquaStress project investigates multiple stress in aquatic systems across multiple levels of biological organization and to assess to what extent multiple stress effects occurring at higher levels of organization can be predicted/explained based on observations of effects occurring at lower levels.
    http://sites.google.com/site/aquastressproject

  • Daphnia Genomics Consortium

Published on November 6, 2012

LMAE at SETAC Longbeachsetaclogo2

The research group Environmental Toxicology will be presenting some of its research at the SETAC North America 33rd Annual Meeting in Longbeach, California from 11-15 November 2012. Come and see us at these dates and places!

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