New Publications

We performed an environmental risk assessment for microplastics (<5 mm) in the marine environment by estimating the order of magnitude of the past, present and future concentrations based on global plastic production data. In 2100, from 9.6 to 48.8 particles m−3 are predicted to float around in the ocean, which is a 50-fold increase compared to the present-day concentrations. From a meta-analysis with effect data available in literature, we derived a safe concentration of 6650 buoyant particles m−3 below which adverse effects are not likely to occur.
The hardness values of a substantial proportion of Australian freshwaters fall below the application boundary of the existing European nickel biotic ligand models (Ni BLMs) of 2 mg Ca/L. Modifications were made to the Ni BLM by increasing the binding constants for Ca and Mg at the biotic ligand to account for softer waters encountered in Australia and the more important competitive effect of Ca and Mg on Ni toxicity.
Under natural conditions, organisms can experience a variety of abiotic (e.g., temperature, pH) and biotic (e.g., species interactions) factors, which can interact with toxicant effects. By ignoring species interactions conventional ecotoxicological studies (i.e., single‐species tests) oversimplify the actual field situation. We investigated whether temperature and interspecific competition affected the effects of zinc (Zn) on a Daphnia longispina population.
Human activities increasingly impact the functioning of marine food webs, but anthropogenic stressors are seldom included in ecological study designs. Diet quality, as distinct from just diet quantity, has moreover rarely been highlighted in food web studies in a stress context. We measured the effects of metal and pesticide stress (copper and atrazine) on the contribution of a benthic intertidal diatom community to two processes that are key to the functioning of intertidal systems: biomass (diet quantity) and lipid (diet quality) production. 

Toxicity of nickel to aquatic organisms is known to be affected by factors such as dissolved organic carbon (DOC) concentration and water hardness. Bioavailability models have been developed more than a decade ago that have been validated for European surface waters. Australian surface waters, however, are quite different in composition. This collaborative research with Australian, UK, and USA researchers resulted in slightly modified bioavailability models for a range of indigenous organisms that are shown to predict nickel toxicity in local waters relatively accurately. These models can be used in Australian water quality guideline derivations.

Environmental risk assessment of chemicals is mostly based on ecotoxicity studies under standard and not always realistic conditions of temperature and nutrient levels. In this collaborative study with universities of Wageningen, Leuven, and Namur, we performed an aquatic model ecosystem experiment, which showed that temperature and phosphorus loading to freshwater systems can modify the effects of chemical pollution on the structure (e.g. species composition) and functioning of aquatic ecosystems. We argue that factors like temperature and nutrient levels should be taken into account when evaluating the risks of chemicals in the environment.

It is generally assumed that as long as the majority of species experiences no direct adverse effects due to a single substance (i.e. Potentially Affected Fraction, PAF < 5%), no significant structural or functional effects at community‐level are expected to occur. Whether this assumption holds for mixed metal contamination is not known. Here, we tested this by performing a microcosm experiment in which a naturally occurring freshwater planktonic community was exposed to a Cu‐Ni‐Zn mixture for 8 weeks, and in which various structural and functional community‐level traits were assessed.

Understanding how biodiversity affects ecosystem functioning is essential for assessing the consequences of ongoing biodiversity changes. An increasing number of studies, however, show that environmental conditions affect the shape of BEF relationships. Here, we first use a game‐theoretic community model to reveal that a unimodal response of the BEF slope can be expected along environmental stress gradients, but also how the ecological mechanisms underlying this response may vary depending on how stress affects species interactions.

Our freshwater ecosystems are severely threatened by many factors including pollution and climate change. In the current synthesis, we focus on the potential role of epigenetics (molecular modifications of DNA that do not change the DNA sequence). We highlight examples of the roles of DNA methylation and histone modifications, well-known epigenetic mechanisms, in the response to climate change. We conclude by pinpointing the most promising avenues for future research directions to improve our understanding on how freshwater organisms cope with climate change. With this synthesis, we provide a thorough summary of the field and put forward key research questions that need to be addressed.

Mixture effects of chemicals and their potential synergistic interactions are of great concern to the public and regulatory authorities worldwide. Discharges of chemical mixtures to marine waters might possibly have adverse effects on the aquatic communities and for the trophic food web. This study addresses ecotoxicological and biochemical effects of mixtures of the metal copper and a herbicide on a marine diatom and an estuarine calanoid copepod.

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