New Publications

Ecological risk assessment (ERA) is commonly based on single generation ecotoxicological tests that are usually performed at one standard temperature. We investigate the effects of nickel (Ni) on Daphnia magna reproduction at 15, 20 and 25°C along four generations.
The population structure of the non-indigenous calanoid copepod Pseudodiaptomus marinus (Sato, 1913) in the Belgian part of the North Sea (BPNS) is reported for the first time. Detailed P. marinus abundance data including sex and age class of the individuals was gathered on a monthly basis from February 2015 to February 2016 at six sites within the BPNS and Belgian harbors.
Under natural conditions, organisms can experience a variety of abiotic (e.g. temperature, pH) and biotic (e.g. species interactions) conditions, which can interact with toxicant effects. By ignoring species interactions conventional ecotoxicological studies (i.e. single species tests) oversimplify the actual field situation. Here, we investigated whether temperature and interspecific competition affected the effects of zinc on a Daphnia longispina population.
Urban regions of the world are expanding rapidly, placing additional stress on water resources. These water bodies receive chemical emissions arising from either single or multiple point sources, diffuse sources which can be continuous, intermittent, or seasonal. Thus, aquatic organisms in these water bodies are exposed to temporally and compositionally variable mixtures. We have delineated source-specific signatures of these mixtures for diffuse urban runoff and urban point source exposure scenarios to support risk assessment and management of these mixtures.

Copepods are an important component of aquatic ecosystems and constitute a large portion of the total animal biomass on earth. Over the last few decades, the copepod Nitocra spinipes has become a popular test species in environmental toxicity studies. While the amount of short- and long-term toxicity data for this species keeps increasing, little is known about the mechanisms that lead to observable effects on e.g. its growth, development, and reproduction. The Dynamic Energy Budget (DEB) theory can help increase our understanding of those processes. 

Although metal mixture toxicity has been studied relatively intensely, there is no general consensus yet on how to incorporate metal mixture toxicity into aquatic risk assessment. Here, we combined existing data on chronic metal mixture toxicity at the species level with species-sensitivity-distribution (SSD)-based in-silico metal mixture risk predictions at the community-level for mixtures of Ni, Zn, Cu, Cd and Pb, in order to develop a tiered risk assessment scheme for metal mixtures in freshwater.

In ponds, lakes and other water bodies, organisms face a multitude of environmental challenges which include chemical pollution and harmful algal blooms. To better understand and protect our water bodies, we need to be able to model and predict how organisms grow and reproduce under these environmental challenges. Here, we use gene expression patterns in combination with network methodology and statistical modelling to predict the reproduction of waterfleas after exposure to insecticides and cyanobacteria at environmentally relevant concentrations. Our developed models were able to predict reproduction of waterfleas under these different conditions. In particular, the models were able to predict the combined effect of combinations of insecticides and cyanobacteria on the reproduction of the waterfleas. These results provide a valuable mechanistic framework that consists of using gene expression data to quantify higher level effects.

Freshwater biota are usually exposed to mixtures of different metals in the environment, which raises concern because risk-assessment procedures for metals are still mainly based on single-metal toxicity. Because microalgae are primary producers and therefore at the base of the food web, it is of utmost importance to understand the effects of metal mixtures on these organisms. The objective of the present study was to test if combined effects of mixtures to Pseudokirchneriella subcapitata were the same or different across natural waters showing diverse water-chemistry characteristics. This was done by performing experiments with ternary Cu–Ni–Zn mixtures in 3 natural waters and with binary Cu–Ni mixtures in 5 natural waters.

Little is known about the effect of metal mixtures on marine organisms, especially after exposure to environmentally realistic concentrations. This information is, however, required to evaluate the need to include mixtures in future l risk assessment procedures. We assessed the effect of copper (Cu)–Nickel (Ni) binary mixtures on Mytilus edulis larval development using a full factorial design that included environmentally relevant metal concentrations and ratios.

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.