SETAC Globe - Environmental Quality Through Science
  21 July 2011
Volume 12 Issue 7

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Ecotoxicology Session Track Highlights

Matthias Liess, Helmholtz Center for Environmental Research – UFZ, Germany

The essence of the ocean cannot be seen in a drop of seawater.
Kurt Tucholsky, 1925

When organising a talk about session track highlights, one possible way to start is by splitting up the body of presentations into some representative categories. It didn’t take long, though, to realise that this wasn’t going to work well for organising a talk about the Milan ecotoxicology session track. After reviewing the abstract book, hearing many of the talks, and seeing many of the posters, it became apparent that practitioners are increasingly embracing complexity by adopting a more holistic perspective in designing and conducting their ecotoxicological investigations, and that perhaps the unifying theme of the Milan ecotoxicology session track would be “Understanding and Predicting by Linking Disciplines.”

We are including more and more effect-determining parameters — environmental stressors, biological stressors — which are determining the effect of a contaminant on a certain species or a particular population. One example, out of many possible examples, comes from a presentation by Agatz et al. (ET04-2) entitled “Effects at a Daily Resolution of Imidacloprid on the Individual Feeding Activity of Gammarus pulex (L.).” They presented data showing that individual feeding rate in the crustacean Gammarus pulex is body-mass dependent, with higher feeding rates occurring at low body masses. The point illustrated by that presentation is that it is very important to understand the feeding rate-body weight dependency in order to be able to understand and predict the effects of contaminants on this species.

As we have increasingly incorporated more causal factors into our ecotoxicological studies, we have also, increasingly, recognised the need to simplify by using ecological traits, rather than species, as our endpoints for assessing ecotoxicological effects. Ecological trait-based assessment seems to be very much on the rise, based on the frequency with which it occurred in this year’s presentations. Overall there were at least 18 talks and posters on ecological trait-based assessment, scattered across several sessions including:

  • Climate Changes, Biological Invasions and Pollution (CS01)
  • Ecologically Relevant Endpoints (ET04)
  • Environmental Fate and Exposure of Pharmaceuticals and Personal Care Products (PPCPs) (EC05)
  • Environmental Risk Assessment and Management of Plant Protection Products (PPPs) and Biocides (RA04)
  • Impact and Remediation of Wastewater (HM02)
  • Integrated Science: Key to Risk Assessment (RA05)
  • Metals and Metalloids in the Environment: Adaptation, Bioavailability and Speciation (ET12)
  • Monitoring and Modelling Stressed Ecosystems to Support Ecosystem-based Management (EH02)
  • The Future of Ecotoxicological Risk Assessment: Biological Traits, Ecological Vulnerability, Improved SSDs, Indirect Ecological Effects (RA13)

That leads to another topic that seemed to gain momentum at this year’s meeting, which is ecotoxicological modelling, i.e., the use of models to link toxicological data with protection goals that are based on ecological effects, not just toxicological effects.

There was an interesting session on this topic, “Mechanistic Modelling for Risk Assessment: Sub-lethal Responses and Population-level Effects (ET11).” One of the compelling notions presented at this conference was that to link toxicological effects to ecological effects considering field conditions, we need to do exposure modelling. To do that, we need to understand the population structure and the landscape structure. This is necessary, for example, in order to consider recolonisation potential following spatially and temporally limited exposures to chemicals in the field. These considerations are relevant because the “ecological dose-response relationship” is very different from what we see in laboratory or mesocosm investigations. From here it is not much of a stretch to realise that exposure modelling and ecological modelling provide a bridge from ecotoxicology to ecosystem services.

modeling graph

There was a nice industry perspective presentation on ecotoxicological modelling by Thorbek et al. (ET11A-4) entitled “Using Ecological Modelling to Link Ecotoxicological Data with Protection Goals.” Regulators, too, are looking at this subject of ecotoxicological modelling, and of course they too are interested in these new methods. Regulators, though, have to be conservative and can’t run after every new idea because they would be only running, not regulating. There was a nice presentation on the regulatory perspective by Duquesne et al. (ET11A-2) entitled “Concerns and Needs of Regulators to Use Ecological Modelling in Risk Assessment of Pesticides” that talked about factors that might lead risk assessors, armed with ecotoxicological data, to underestimate effects on populations and communities within the ecological context.

This brings us back to the issue of complexity. Myriad parameters should be considered — including those that attenuate as well as those that amplify effects — as one progresses from the individual organism in the laboratory to the population (or perhaps ecological trait) in the ecosystem. We need to know all the parameters that importantly influence the effects of chemicals on populations and ecosystem traits. That is the problem. It is an important one that we are working to have the answers to.

A very interesting Canadian study by Kreutzweiser and Thompson was presented (ET04-3), entitled “Non-guideline Studies Refine and Improve the Aquatic Risk Assessment of Forest Insecticides Imidacloprid and Neem.” This is a good example, representing many other studies, of the importance of having a good site-specific conceptual model for planning useful ecological risk assessments. Here you see a maple tree that is being attacked by some bugs, and so it is being treated with systemic insecticides. If one were to do a risk assessment of this action without a good site-specific conceptual model, chances are that it would be a terrestrial risk assessment. However, the leaves from maple trees find their way into aquatic ecosystems, and therefore aquatic invertebrates also are potentially at risk from exposure to the insecticides injected into the maple trees. Without careful thought, this relevant exposure pathway would likely be missed.

How do we avoid that? In the case of pesticides, one way to consider the unexpected is to conduct post-registration monitoring, both for exposure and for effect. Aagaard et al. provided a nice poster (MO369) on post-registration exposure monitoring entitled “Predicting Input of Pesticides to Surface Water via Drains — Comparing Post Registration Monitoring Data with MACRO Model Predictions.” Post-registration effects monitoring was well represented, for example by the presentation from Maaben et al. (ET04-5), “Impact of Pesticides in Small Streams in Central Germany — Effect of Pesticides on Macroinvertebrate Drift, Emergence and Feeding Rates of Gammarus pulex.” The take away message from the presentations on post-registration monitoring was that it is very important that we not rely soley on experimental predictions from the lab or mesocosm. We also have to observe what is actually happening in the ecosystem to verify our experimental predictions.

screen-capture-1.pdfThese are impressions of what ecotoxicologists were talking about at the 2011 SETAC Europe meeting in Milan. Now I will turn my attention to some of the unsolved questions that deserve attention during the 2012 SETAC World Congress in Berlin. There are some fundamental issues that must be addressed in Berlin, including how to characterise and manage the risks from low-level environmental exposures. 800x.jpgThis basic questions underlies many of the major environmental problems that we are dealing with today. For example, there is still a lot of debate on whether and how insecticides and other pesticides are acting on agricultural ecosystems. This topic is not yet finalized. Another such issue is oil spills in general, and the 2010 Gulf of Mexico Deepwater Horizon oil spill in particular. The ecotoxicological impacts of the spill are still not clear, or for that matter even the fate of the oil that was spilled. These questions will continue to deserve our attention.

The Fukushima nuclear disaster is another case in point, in the sense that there are major uncertainties and disagreements among experts about the risks from low-level environmental exposures, and how to manage them.

Finally, image-191450-galleryV9-wpeh.jpgthere is global climate change. Climate change is having direct effects, for example on rainfall patterns and reservoir levels but also indirect effects. For example, warming condistions may lead to greater use of pesticides to control increasing mosquito populations with unknown effects on beneficial non-target species.

The fundamental issue of how to characterize and manage the risks from low-level environmental exposures is a topic to which SETAC has a great deal to offer and to which we should turn our attention to during the 2012 SETAC World Congress in Berlin.

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