New Publications

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?

HA

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

reviewsinfish

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

EnvSciPol

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.

Toxicity data for modeling impacts of oil components in an Arctic ecosystem

10646Today, modeling has become an invaluable tool to extrapolate impacts of toxicants from an individual to the population level. As such, it is essential for ecosystem-based approaches to impact assessment. For modelling purposes, this study synthesized available literature on the effects of petroleum related discharges on selected cold-water marine species (plankton and fish). The resulting dataset is to be used by ecotoxicology algorithms included in an ecosystem-based modeling system that combines both ecological and toxicological knowledge into a single modeling framework. We believe this study is of general value to the ecotoxicology community in two ways: first, the assembled data are of use to others engaged in the development and/or application of ecotoxicology models. Second, the results indicate where further ecotoxicology research will be of greatest value for both increasing general knowledge on cold-water ecotoxicology and for designing new ecotoxicology studies for modeling applications.

A comparison of the short-term toxicity of cadmium to indigenous and alien gammarid species

10646Alien invasive species (AIS) are, next to global change, considered to be one of the major threats to global biodiversity. Globalisation and habitat deterioration positively contribute to the establishment success of AIS. Besides appropriate vectors of introduction and favourable environmental conditions their success can be attributed to species specific traits such as a high reproduction rate, an omnivorous diet and the ability to easily cope with changing environmental conditions. In this study, we hypothesized that AIS are more tolerant to metal pollution compared to native species. We tested this hypothesis based on a comparison between native and alien freshwater shrimps that were exposed to different concentrations of cadmium. We found significant differences in sensitivity to metal pollution between different species which should be taken into consideration in environmental risk assessment and water quality standard setting. There was no clear trend in Cd sensitivity between native and alien shrimps, indicating that alien species do not have an advantage over native ones in cadmium contaminated waters.  

Latest study on gene-expression respones in the waterflea to combined stressors featured on ChemicalWatch.com

ESnT

Genetic responses to environmental chemicals do not always correlate with higher-level effects, such as growth and reproduction in aquatic test species, according to our latest study recently published in the journal Environmental Science & Technology. This finding potentially has important implications for risk assessment in relation to the Adverse Outcome Pathways (AOP) framework. AOPs try to predict responses at higher biological levels, which are more relevant for risk assessment, starting from genetic responses. ChemicalWatch.com, an online repository which provides businesses with the information they need to manage the risks of chemicals responsibly, has recognized the important value of these findings and featured the study on their website. More information can be found on ChemicalWatch.com. The website allows a free 14-day trial which gives access to the full text.

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.

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.

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