New Publications

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.

Toxicity of lead (Pb) to freshwater green algae: Development and validation of a bioavailability model and inter-species sensitivity

aquatic toxicology thumb100 Scientifically sound risk assessment and derivation of environmental quality standards for lead (Pb) in the freshwater environment are hampered by insufficient data on chronic toxicity and bioavailability to unicellular green algae. Here, we first performed comparative chronic (72-h) toxicity tests with three algal species in medium at pH 6, containing 4 mg fulvic acid (FA)/L and containing organic phosphorous (P), i.e. glycerol-2-phosphate, instead of PO43− to prevent lead-phosphate mineral precipitation. Pseudokirchneriella subcapitata was 4-fold more sensitive to Pb than Chlorella kesslerii, with Chlamydomonas reinhardtii in the middle. The influence of medium physico-chemistry was therefore investigated in detail with P. subcapitata. In synthetic test media, higher concentrations of fulvic acid or lower pH protected against toxicity of (filtered) Pb to P. subcapitata, while effects of increased Ca or Mg on Pb toxicity were less clear. When toxicity was expressed on a free Pb2+ ion activity basis, a log-linear, 260-fold increase of toxicity was observed between pH 6.0 and 7.6. Effects of fulvic acid were calculated to be much more limited (1.9-fold) and were probably even non-existent (depending on the affinity constant for Pb binding to fulvic acid that was used for calculating speciation).

Microplastics in bivalves cultured for human consumption

env pollutToday, 27 years after Cpt. Charles J. Moore first discovered the Great Pacific Garbage Patch, marine plastic pollution continues to be a growing threat to the marine environment. As plastic debris is ubiquitious across the world's seas and oceans, the consequences of macroplastics for most (vertebrate) wildlife have been identified over the years. Yet, to date, the impacts of microplastics are less understood. These plastic particles (< 1mm), which are found in cosmetics and can be formed through the degradation of larger plastic items, are becoming increasingly abundant. As our research has shown, they can now be found from the surface layer all the way down to the deep-sea sediment. Worringly, microplastics can be ingested by a wide range of marine organisms because of their small dimensions which in turn creates an understudied risk of exposure for human consumers. Here we present the first study to report on the possible consequences of marine microplastics for human consumers by analysing the occurence of microplastics in commercially available shellfish. From our results, we calculated that the average European shellfish consumer has an uptake of 6400 microplastics per year. As there is a lack of (mammal) effect studies, this exposure poses an unknown risk for human health.

Inferring time-variable effects of nutrient enrichment on marine ecosystems using inverse modelling and ecological network analysis

scitotenv thumb100 Despite the restrictions imposed by the ever increasing legislation, anthropogenic nutrient inputs continue to be a worldwide threat to our marine ecosystems. The resulting elevated nitrogen and phosphorus concentrations can promote intensive algal blooms which may decrease transparancy, deplete oxygen and change the composition of the fish community. In recent years, these ecosystem-level consequences  of anthropogenic nutrient enrichment are being studied from a topological perspective (ie. who eats whom). However, it has been noted that this perspective is insufficient to understand the magnitudes of energy and materials that flow through natural food webs. To circumvent this, we used a mesocosm approach combined with linear inverse modelling to estimate carbon flows in a foodweb subjected to different nutrient treatments. In doing so, we found that the systems activity is positively but nonlinearly affected by the addition of nutrients. Surprisingly, detritus appears to be a crucial, if not predominant, driver of the ecosystem functioning under all nutrient conditions.

Are there species-specific tolerances towards cyanobacteria in Daphnia?


Cyanobacterial blooms have been a growing environmental concern due to their ability to produce toxins. Yet to date, few studies have focused on comparing the effects of different cyanobacteria. In this publication, we determined the effects of six common cyanobacteria on two keystone species in the aquatic environment, Daphnia magna and Daphnia pulex. Sensitivity depended upon the concentration of the cyanobacteria and differed between the Daphnia species. The publication of this paper coincided with the recent webinar organised by US EPA on cyanobacterial blooms as well as the approval of president Obama to sign the bill on research on toxic algae, both indicating the need for research on cyanobacterial blooms. Our paper concluded by highlighting the importance of concentration response curves to evaluate the toxicity of cyanobacteria to multiple zooplankton species in the environmental risk assessment.


Are interactive effects of harmful algal blooms and copper pollution a concern for water quality management?

water researchCyanobacteria, commonly known as harmful algae due to their adverse effects on aquatic organisms, are a major concern to water quality. While it is well-known that cyanobacteria reduce the fitness of Daphnia sp., their combined effects with chemicals have hardly been documented. In our recent paper, we investigate how cyanobacteria act together with copper, commonly used in algaecides and fungicides, to impact the model organism Daphnia. The results show that cyanobacteria and copper together can considerably impair daphnid reproduction but that their combined effects are overall close to expectations based on their individual toxicities and hence of limited concern for water quality management.

Environmental effects on fished lobsters and crabs


In times of climate change, when the sea temperatures are increasing in the world oceans, and ocean acidification is becoming and increasing concern, information of environmental effects on key life history stages of important species is important and needs to be readily available. Lobsters and crabs are key commercial species, and due to their complex life cycle different environmental variable may have dissimilar effects on their abundance, depending on the life stage considered. This review will be very valuable for managers, fishermen as well as scientists alike.


The ChimERA project: coupling mechanistic exposure and effect models into an integrated platform for ecological risk assessment


Typically, environmental exposure and the expected ecological effects are assessed separately. Yet for the last 25 years, the environmental realism, the ecological relevance, and the methodological accuracy of these official procedures have been questioned. Bearing in mind the ecological and environmental complexity inherent to natural ecosystems, risk assessors increasingly realise that ecological risk cannot be adequately assessed while disregarding most, if not all, of this complexity. Exposure to chemicals is not constant in time nor is it homogeneously distributed in space. This may allow for recovery-inducing processes at the individual, population, and community level. In addition, real ecosystems may be faced with the combined effects of multiple stressors. Moreover, this approach neglects that functional redundancy may compensate species loss and sustain functions in stressed ecosystems. Experimentally examining the effects of multiple stressors at higher levels of biological organisation from multiple exposure scenarios in various geographical areas is an informative exercise but cannot be considered as a standard approach for ERA. Instead, new models are needed which can be extrapolated to many different alternative scenarios. In this paper, we outline the methodology and objectives of a new project which will answer this need.