New Publications

The degree of biological variability within a population is an important factor for its ecological success. Yet, individual-based population models (IBMs) that utilize the Dynamic Energy Budget (DEB) theory as a mechanistic basis to simulate an individual's life history, largely rely on rule-of-thumb estimates of inter-individual variability of their parameter values. In this study, we explored how data from previous life-history experiments with the copepod Nitocra spinipes could be used to make realistic estimates of variability in DEB parameter values for this species.
Water quality standards for cobalt (Co) have not been developed for the European Union or United States. The objective of the present study was to produce freshwater Co toxicity data that could be used by both the European Union and the United States to develop appropriate regulatory standards (i.e., environmental quality standards or predicted‐no‐effect concentrations in Europe and ambient water quality criteria or state water quality standards in the United States). Eleven species, including algae, an aquatic plant, and several invertebrate and fish species, were used in the performance of acute and chronic Co toxicity tests.

Respiratory exposure to marine toxins in sea spray can induce both health‐affecting and potential health‐promoting mechanisms. All depends on the specific toxins and their inhaled dose. In this explorative (in vitro) study we used lung cells to examine this matter. As such we found that yessotoxins downregulate the important mTOR cell signaling pathway in lung cells. This pathway is related to multiple pathological conditions. In summary, this research supports the theory that the inhalation of natural products via sea spray is health promoting (i.e., the biogenics hypothesis).

Water quality standards for cobalt (Co) have not been developed for the European Union or United States. The objective of this research was to produce freshwater Co toxicity data that could be used by both the EU and US to develop appropriate regulatory standards. Eleven species, including algae, an aquatic plant, and several invertebrate and fish species, were used in the performance of acute and chronic Co toxicity tests. Results indicated that invertebrate and algae/plant species are more sensitive to chronic Co exposures than fish. Following the European‐based approach and using EC10 values, species sensitivity distributions (SSD) were developed and a median hazardous concentration for 5% of the organisms (HC5,50%) of 1.80 µg Co/L was derived. Chronic EC20 values were used, also in a SSD approach, to derive a US EPA‐style final chronic value (FCV) of 7.13 µg Co/L.
In this paper, we describe and evaluate the construction of a metatranscriptome dataset from a pelagic crustacean zooplankton community. We sampled zooplankton in one marine station, named LW02, in the North Sea, in both winter and summer, and generated transcripts using Oxford Nanopore Technology (ONT), a third-generation nanopore-based sequencing technology. ONT is, uniquely, capable of sequencing RNA directly, rather than depending on reverse transcription and PCR, and applicable to be used directly in the field. We found that metatranscriptomics is capable of species detection, including screening for the presence of endoparasites, hence competing with morphological identification. The most abundant mRNA transcripts with known function coded for essential metabolic processes. Although small in scale, our study provides the basis for future efforts to characterize the metatranscriptome of marine zooplankton communities and its application in biomonitoring programs.
In the present study, we aimed to test the protectiveness of the bioavailability-normalisation procedure, with its associated hazardous concentrations for x% of the species (HCx), that is currently implemented to derive environmental threshold concentrations for Ni in European environmental legislative frameworks. We exposed a natural plankton-dominated community to three constant Ni concentrations during a 56d-microcosm experiment under high DOC conditions. The effects of the bioavailability-normalised HC5 and HC50 were evaluated at the level of the community structure, community functioning  and individual species abundances.
In this research we investigated whether or not marine algae growth was affected when exposed to environmentally realistic mixtures of chemicals collected from the Belgian part of the North Sea (BPNS). To explore this, we used a specific sampling technique that “filters” chemicals from the seawater and collects them in a way allowing to transfer these mixtures from the field to the laboratory. Once brought to the lab, we determined the concentration levels of 88 personal care products, pesticides and pharmaceuticals. Next, we exposed marine algae to the so collected mixtures of chemicals and recorded the algae’s growth over three days. We surprisingly observed growth stimulation for those mixtures with less sample handling and short storage while those undergoing repeated handling and longer storage showed no effects. In an explorative try to define the differences in the mixture composition of the effect- and no-effect causing samples, we were indeed able to define these differences but our findings could not be linked to the biological effects observed. In conclusion, we have shown that environmentally realistic mixtures of contaminants collected in the BPNS can enhance the growth of a marine algae species but it remains challenging to define those substances within these mixtures that actually cause effects on algae growth.

Recent studies have shown that toxicity of metals to Daphnia magna depends on the temperature. In a population experiment, we investigated if the effect of temperature on nickel (Ni) sensitivity observed on the apical level can be extrapolated to the population level. However, we observed no consistent population-level effects of Ni at concentrations that significantly affected reproduction. An individual-based model (IBM) with the dynamic energy budget (DEB) theory for Daphnia magna was calibrated based on Ni toxicity data at three temperatures (15, 20 and 25°C). Using the model, we confirmed the unexpected absence of Ni effects at the population level. 

Over the past decade, significant advances have been made to unravel molecular mechanisms of stress response in different ecotoxicological model species. Within this study, we focus on population level transcriptomic responses of a natural population of Daphnia magna to heavy metals. We aim to characterize the population level transcriptomic responses, which include standing genetic variation, and improve our understanding on how populations respond to environmental stress at a molecular level.

In this study, we assess the relationship between beta-diversity (measured as Bray–Curtis dissimilarity) and regional productivity (measured as biovolume) under various levels of a stressor flux in meta-ecosystems that were composed of two marine micro-algae communities. We created heterogeneity by exposing one of the two communities to a herbicide and manipulated regional diversity by applying a dispersal gradient, which decreased beta-diversity.