News

Published on November 9, 2017

Understanding and predicting ecosystem functioning under environmental change has become a focus in ecological research due to the impact of human activities on natural ecosystems and the services they deliver. Ecosystem functioning under stress can depend on whether the response traits driving changes in species densities also predict direct stress effects on the species’ contribution to functioning. Based on our results, we expect a disproportionate loss of functioning when traits driving species densities do not allow to maintain ecosystem functioning under stress.

Published on October 20, 2017

We are happy to announce that Sam Baelus, who performed her master dissertation at our Lab, has won the ArcelorMittal Indaver Thesis Award “Environmental Science and Technology”. This award was given for the 23rd time to outstanding Master students who wrote a thesis on an environmental topic. Sam, Master of Bio-science engineering in Environmental technology, wrote her thesis on the “Characterization of phycotoxins in sea spray aerosols". Here a new method was proposed to measure background concentration of algal toxins and other biogenic chemicals in the sea air. These compounds are considered, within the biogenics hypothesis, as the health promoting substances in sea air. We wish her all the best in her future career. Congratulations Sam!

Published on October 20, 2017

Tetracycline is a commonly used antibiotic in aquaculture, veterinary and agriculture. Due to its widespread use, tetracycline is commonly found in our environment where it can harm other organisms. Here we studied the effects of tetracycline on the waterflea daphnia. We particularly focused on studying the long-term effects of tetracycline, which consists of three generations of daphnia exposed to tetracycline (from grandparents to grandchildren) at the molecular level. We observed effects of tetracycline in all generations particularly targeted the molting related genes, which are in daphnia also responsible for growth. We also observed that when exposing daphnia to different concentrations of tetracycline specific genes called vitellogenin were affected and these genes could be linked to effects on reproduction. Our results show that the effects of chemicals to different generations and to different concentrations are very different and that these effects cannot be neglected in the environmental risk assessment of tetracycline.

Published on October 20, 2017

Metal contamination of rivers and streams generally occurs as a combination of multiple metals (also called mixtures). However, it is yet unresolved how risks of mixed metal contamination to ecosystems should be evaluated. To increase the knowledge about chronic mixture effects, the authors investigated whether metal mixture effects are dependent on the biological species, mixture composition, and metal concentration ratio. The authors evaluated the effects of quaternary Ni-Zn-Cu-Cd and ternary Ni-Zn-Cu mixtures on 48-h algal growth rate (Pseudokirchneriella subcapitata) and 7-d daphnid reproduction (Ceriodaphnia dubia) using a ray design.

Published on September 19, 2017

To obtain a better understanding of the biological responses to unpredictable environmental change, the early transcriptional response of the keystone species Daphnia magna to twelve environmental perturbations was characterised. We discovered that approximately one-third of the Daphnia genes, enriched for metabolism, cell signalling and general stress response, drives transcriptional early response to environmental stress and it is shared among genetic backgrounds. 

Published on June 14, 2017

To assess the consequences of ongoing biodiversity changes, hundreds of biodiversity experiments have been carried out since the 1990s. However, changes in ecosystem functioning between systems can not only result from differences in the number of species, but also from differences in what species are present (i.e. species identities). Additive partitioning methods are therefore generally used in biodiversity research. These factor out species identify effects by comparing the observed level of ecosystem functioning against that predicted by the null model for the given species composition of the system. These species’ deviations from the null can be partitioned between several terms reflecting the various mechanisms through which biodiversity can affect ecosystem functioning. Current partitioning methods, however, quantify biodiversity effects based on linear relationships between species functional traits and their deviations from the null model. In this paper, we demonstrate that non-linear relationships frequently occur, and derived a non-linear extension of additive partitioning methods to quantify these more complex biodiversity effects on ecosystem functioning.

Published on May 16, 2017
Toxicity of metals like zinc (Zn) to freshwater organisms is not only dependent on the concentration of the metals itself, but also on other properties of the water, like its hardness and its acidity (pH). This is called bioavailability. In the European Union, safe levels of Zn can be calculated as a function of these properties, using so-called bioavailability models. Previously, the existing models could not be applied to more than 25% of European waters, because hardness or pH were higher than those for which the models were originally developed. In this research, we have shown with new experimental work that the existing model for algae can also be used at a much wider range of hardness and pH than previously thought. Our work with water fleas, however, showed that the existing model needed to be considerably improved.

Published on May 9, 2017

This week, 10 GhEnToxLab members will be presenting their research at the 27th SETAC Europe Annual Meeting in Brussels, Belgium from 07-11 May 2017. There we will highlight our research in a total of 5 platforms, 5 posters and 1 poster corner. To keep track of us during the conference, a comprehensive list of our activities is provided below. Not only do we present a lot of our work, many GhEnToxLab members are part of the local organising committee and professor De Schamphelaere is the chair of the scientific committee of the conference.

Published on April 3, 2017
Metal contamination of rivers and streams generally occurs as a combination of multiple metals (so called mixtures). However, it is yet unresolved how risks of mixed metal contamination to ecosystems should be evaluated. We collated data from 30 different toxicity tests with metal mixtures and analysed them in a systematic way to derive general conclusions that can be used in risk assessment. We found  cases in which different metals, each individually causing <10% toxicity (relative to uncontaminated water), caused much larger toxicity (up to 66%) when combined. This suggests that the current metal-by-metal approach in risk assessment may not be conservative enough for the environment. We also considered the use of two common mixture toxicity models to predict metal mixture toxicity.

Published on March 30, 2017
Copepods play a fundamental role in the food chain of our oceans as they feed on algae and get eaten by fish. Amongst others, the harpacticoid copepod species Nitocra spinipes has become a popular model species in aquatic toxicity testing over the past few decades. To understand the combined effects of chemical pollution and climate change-related stressors on copepod populations, a proper quantification of those processes is essential. In this study, GhEnToxLab researcher Josef Koch and his Swedish coauthors (Stockholm University) quantified the effects of temperature and food shortage as two climate change-related environmental stressors on Nitocra spinipes and implemented the corresponding stress functions into an individual-based population model for this species.

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