New Publications

Through global shipping and trade, mankind has inadvertently spread marine organisms to such an extent that many are now considered cosmopolitan. Further aggravated by changes in the foodweb structure (overfishing), eutrophication and climate change, this has led to a substantial increase in the occurrence of harmful algal blooms (HABs). Next to the large potential for environmental damage, these recurring events have become a global public health concern as many species produce potent marine toxins that may lead to shellfish poisoning. To ensure food safety, the mouse bioassay has long been used to screen seafood for the presence of these toxins. Due to ethical concerns, however, this test is now being replaced by alternative chemical analyses.

Microplastic pollution is increasingly being considered as a threat to the marine environment in general and to small marine invertebrates at the base of the food chain in particlular As microplastics occur both in the seawater and in the sediment, we investigated the potential for microplastic ingestion in two organisms inhabiting these environments: the blue mussel (Mytilus edulis) and the lugworm (Arenicola marina). As a follow-up to our previously published research, the microplastic load in field-collected organisms - i.e. exposed to ambient microplastic concentrations - was assessed.  In all collected specimens, we detected low concentrations of microplastics in both species, although the sediment dwelling lugworms contained somewhat higher concentrations. Subsequently, potential impacts of microplastic uptake of these species were assessed. Although some responses were measured, we detected no significant adverse effects of microplastic ingestion.

In a recent research paper published in Chemosphere, Gert Everaert and co-workers quantified the relative contribution of persistent organic pollutants to marine phytoplankton biomass dynamics. To do so, they used concentrations of persistent organic pollutants (POPs) to infer potential POP-induced effects on marine primary production in the Kattegat and the North Sea. They modelled phytoplankton dynamics using four classical drivers (light and nutrient availability, temperature and zooplankton grazing) and tested whether extending this model with a POP-induced phytoplankton growth limitation term improved predictions of the observed chlorophyll a concentrations.

In the European Union and the United States, two differently structured bioavailability models are used in risk assessments of copper. These models, the biotic ligand models (BLM), are valuable tools based on the concept that toxicity depends on the concentration of metal bound to a biological binding site; the biotic ligand. The application of these different BLMs implies that a discrepancy exists between regulation of aquatic toxicity in the U.S. and the E.U. In this study we evaluated the capacity of these BLMs to predict chronic copper toxicity to two water flea clones (Daphnia magna). We found that one BLM performed best with one clone, while the other BLM performed best with the other clone.

Over the last decade, scientific technologies have improved significantly. While it took more than ten years and about 3 billion dollars to sequence the first human genome, prices for genome sequencing are currently plummeting. Now, you can even send your own DNA sample to commercial compagnies for about 100 dollars and learn about your genetic ancestry. Yet, despite this massive amount of data generated, we still cannot understand what the majority of that DNA is doing. Which genes are causing diseases? Which genes are responding to toxicants?

Species interactions are often overlooked when assessing the ecological impact of chemicals. However, they can greatly influence the way a population is affected by a chemical, either increasing or decreasing a chemical’s effects. In this publication, we examined three types of species interactions – intraspecific competition, interspecific competition and predation – in Daphnia magna populations exposed to pyrene. Predation and high initial intraspecific competition were shown to interact antagonistically with pyrene exposure i.e. the effect of pyrene was less pronounced. This was attributed to differences in population structure prior to pyrene exposure and pyrene-induced reductions in predation pressure. This study is a good example of how species interactions can alter the response of a population to chemical exposure in a way that cannot be predicted from single species tests alone.

We investigated the effects of a binary Ni-Zn mixture on chronic reproductive toxicity to the water flea Daphnia magna. The results suggested that the type of interactive effect is dependent on the effect size at which Ni and Zn are combined in the mixture. Weak antagonistic or non-interactive effects occurred in the mixture treatments where each of the individual metals produced insignificant or only weak adverse effects on their own. Conversely, synergistic mixture effects, i.e., stronger effects than expected, only occurred when at least one of both metals in the mixture caused a greater than 20% effect on reproduction. Since low effect sizes are the most relevant ones in most regulatory frameworks, our data suggest that the CA and IA mixture toxicity models can both serve as conservative models for predicting effects of Ni-Zn mixtures.

etc cover thumb100 Recently a harmful algae bloom made Lake Erie's water temporarily undrinkable in Toledo and surrounding towns in northwest Ohio. Over the last 50 years harmful algal blooms have been a regular occurrence in Lake Erie, with peak concentrations in late summer months. Such harmful algal blooms are commonly produced by cyanobacteria and not only impact water quality but they also have the potential to produce toxins that can harm humans, pets and wildlife. The blooms are caused by a combination of factors that promote high densities and reproduction of algae, one major factor being warmer temperatures. Therefore climate change has been linked to the global expansion of cyanobacteria through changes in temperature.

chemosphere thumb100 Due to their extensive use, continuous discharge and inefficient removal by wasterwater treatment plants, increasing levels of antibiotics are commonly detected in surface waters. Even though environmental levels are generally low, it has been shown that long-term exposure may adversely affect aquatic organisms. As such, there is an urgent need to improve classical water treatment techniques.

plantsoilThe biotic ligand model (BLM) is a bioavailability model for metals based on the concept that toxicity depends on the concentration of metal bound to a biological binding site; the biotic ligand. Here, we evaluated the BLM to interpret and explain mixture toxicity of metals (Cu and Zn). The mixture toxicity of Cu and Zn to barley (Hordeum vulgare L.) was tested with a 4 days root elongation test in resin buffered nutrient solutions.

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