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Published on March 3, 2014

Relating taxonomy-based traits of macroinvertebrates with river sediment quality based on Basic and Zero-Inflated Poisson models

ecological informationsDue to growing anthropogenic stress on aquatic ecosystems it is important to have accurate and fast methods for environmental risk assessment. Ecological assessment of freshwaters is traditionally based on the diversity approach where diversity decreases with increasing environmental disturbance. In this paper, we propose a novel approach where modelled changes in trait composition of macroinvertebrates are used to assess the river sediment quality. We hypothesized that the trait composition, in this case the body length of the organisms, would change as metal concentrations increase. We found that the abundance of macroinvertebrate taxa decreased at almost all body lengths with a decreasing quality of the metal contaminated river sediment. It was also found that the number of different body lengths decreased with increasing metal pollution, indicating a decrease in diversity of the macroinvertebrate community. Smaller organisms seemed to be more resistant to metal pollution. This research showed that trait-based ecological risk assessment has high potential, but that possibly other traits besides body length should be included to strengthen our conclusions.

Published on February 19, 2014

Ecotoxicity of binary mixtures of Microcystis aeruginosa and insecticides to Daphnia pulex

env pollutHarmful bluegreen algae such as cyanobacteria can have large impacts on aquatic ecosystems and ponds. Often, these cyanobacteria are not the only form of toxic stress present. In our recent paper, we study how cyanobacteria together with insecticides  used in crop protection can impact the model organism Daphnia. The results show that cyanobacteria and insecticides together can have significant effects on the reproduction of the daphnid. Depending on the type of insecticide used, these effects are  larger, smaller or equal to our expectations.

Published on February 11, 2014

Hard X-ray nanoprobe investigations of the subtissue metal distributions within Daphnia magna

AnalBioChemTo improve our capacity to evaluate the impact of metals on aquatic organisms, the fundamental processes of uptake, elimination and detoxification need to be fully understood. To this end, the freshwater crustacean Daphnia magna has long served as a model organism for studying whole body bio-accumulation. In order to fully comprehend the active regulation of internal concentrations within aquatic biota, the toxicological research needs to move from the microscopic tissue scale towards a (sub)cellular field of view. We developped a novel sample preparation technique which, when coupled to advanced elemental imaging, reveals the distributions of Ca, Fe and Zn within D. magna at the subtissue level. The presented technique was found to be well suited for trace-level bio-imaging which may ultimately aid in the discovery of new insights in the detoxification processes within aquatic model organisms.

Published on January 21, 2014

Additive modelling reveals spatiotemporal PCBs trends in marine sediments 

marinepollutionbulletinThe environmental fate and toxicity of persistent organic pollutants (POPs) are of global concern. Spatiotemporal trend analyses of such hazardous substances are identified as a key priority by the OSPAR commission. In this paper we analyse one of the largest, longest and most complete data sets of PCBs using a regression-based technique in order to compare the levels and time trends of marine and estuarine PCB sediment concentrations between and within the Belgian Coastal Zone (BCZ) and the Western Scheldt estuary. The time trends unraveled a two to three-fold decrease in PCB concentrations in the BCZ during the past 20 years (1991-2010). However, in the Western Scheldt estuary, time trends were spatially heterogeneous and did not exhibit a significant decrease. These results demonstrate that international efforts to reduce PCB emissions have effectively reduced concentrations in open water ecosystems like the BCZ but have not affected urbanized and industrialized areas of the Scheldt estuary. The ten PCB congeners we considered followed the same trend, suggesting that no point sources are present in our study area for these congeners.

Published on January 2, 2014

The Combined Effect of Dissolved Organic Carbon and Salinity on the Bioaccumulation of Copper in Marine Mussel Larvae 

ESnTDue to natural and anthropogenic influences, copper concentrations can be elevated in the aquatic environment. However, the total dissolved Cu concentration is, by itself, an inefficient predictor of copper toxicity. Considerable efforts have been made to improve the prediction of toxic effects by taking into account the aquatic concentration of other elements and dissolved organic carbon (DOC). These models are based on Cu accumulation at a so-called biotic ligand somewhere in the exposed organism. Mussels, and especially the larvae, are very sensitive to copper. Because of their ecological and economical importance, more specific knowledge about the influence of salinity and DOC on Cu accumulation and distribution in mussel larvae was needed. By collaborating with the X-ray microscopy and imaging group of the UGent (XMI), we could use

Published on December 18, 2013

Temporary open access to research articles

open access thumb medium100 100In an effort to make research known to a broader public, Elsevier Publishers recently made some research articles open acces until January 31st, 2014. This is your chance if you are interested in some of the research performed at our lab. Currently, Jana Asselman's article "Transcription patterns of genes encoding four metallothionein homologs in Daphnia pulex exposed to copper and cadmium are time- and homolog-dependent", published in Aqutic Toxicology is open access.

Published on December 18, 2013

An approach to assess the regulatory relevance of micro-evolutionary effects in ecological risk assessment of chemicals: A case-study with Cd

etc thumb medium121 159Through ecological risk assessment (ERA) policy makers try to set protective norms for harmful chemicals in the environment. Typically, such ERAs are based on ecotoxicological research performed in the lab. However, these laboratory conditions tend to lack some measure of realism compared to the actual situation in the environment. For instance, usually only one particular individual of a species is considered in ecotoxicological tests, while in the environment multiple, different individuals are present. As with us, humans, some of these individuals can cope better with a certain chemical in the environment than others. Under continuous presence of such a chemical these, more tolerant, individuals will survive and reproduce, while the other individuals will perish. Overall, the group of individuals will become more tolerant to the chemical, a process which is called micro-evolution. In this most recent paper an approach is suggested to take this micro-evolutionary processes into account in ERA to, ultimately, make our risk assessment of chemicals in the environment more realistic.

Published on November 16, 2013

GhEnToxLab at SETAC Nashville

setaclogo2 thumb100 The Ghent University Laboratory for Environmental Toxicology will be presenting some of its research at the SETAC North America 34th Annual Meeting in Nashville, TN from 17-21 November 2013. Come and see us at the following dates and places:

 

Published on November 12, 2013

The initial tolerance to sub-lethal Cd exposure is the same among ten naïve pond populations of Daphnia magna, but their micro-evolutionary potential to develop resistance is very different

aquatic toxicologyDifferences between the ecological reality in the field and the controlled test conditions in the lab make ecotoxicological results sometimes difficult to extrapolate from the lab to the situation in the field. One of the conditions that are different in the field compared to the lab is the presence of different individuals of an organism. First, each of these individuals differ in their tolerance to toxic stress. Second, the presence of different individuals allow for evolution which results in a group of individuals having a higher tolerance to toxic stress compared to an unevolved group. To characterize these two problems and to investigate possible solutions to them, we compared in our latest paper the tolerance and the potential to evolve in ten groups of individuals orginating from ten natural 'field' populations in Belgium. Although the tolerance of the individuals in these ten groups is quite similar, their potential to evolve an enhanced tolerance is very different.

Published on November 6, 2013

Toxicity – biodiversity relationships unravelled

ecol lettersThe production and use of chemicals is regulated by environmental legislation so as to protect the diversity of our surface waters. Until recently, however, it was impossible to predict the relationship between chemical toxicity and the diversity of aquatic communities, which hampered effective environmental conservation. Together with an international consortium, the laboratory of environmental toxicology (http://www.milieutox.ugent.be, UGent) developed the first theory to predict biodiversity along gradients of toxic stress. Combining this theory to data from polluted algal communities, the scientists reveal that the variability of toxicity tolerance in these communities is five to ten times higher between individuals from the same species than between individuals from different species. The results of this research also demonstrate that this 'within-species variability' is a buffer against species loss in ecosystems polluted with chemicals. These findings, which have been published in the nr 1-ranked ecology journal 'Ecology Letters', raise important concerns regarding the use of species-based tolerance data for environmental protection and explain ecosystem resistance during chemical spills.

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