Ecotoxicology faces the challenge of assessing and predicting the effects of an increasing number of chemical stressors on aquatic species and ecosystems. Herein we review currently applied tools in ecological risk assessment, combining information on exposure with expected biological effects or environmental water quality standards; currently applied effect-based tools are presented based on whether exposure occurs in a controlled laboratory environment or in the field. With increasing ecological relevance the reproducibility, specificity and thus suitability for standardisation of methods tends to diminish. We discuss the use of biomarkers in ecotoxicology including ecotoxicogenomics-based endpoints, which are becoming increasingly important for the detection of sublethal effects. Carefully selected sets of biomarkers allow an assessment of exposure to and effects of toxic chemicals, as well as the health status of organisms and, when combined with chemical analysis, identification of toxicant(s). The promising concept of “adverse outcome pathways (AOP)” links mechanistic responses on the cellular level with whole organism, population, community and potentially ecosystem effects and services. For most toxic mechanisms, however, practical application of AOPs will require more information and the identification of key links between responses, as well as key indicators, at different levels of biological organization, ecosystem functioning and ecosystem services.

/pdf/effect-based-tools-for-monitoring-and-predicting-the-34iw6ey9w9.pdf

Effect-Based Tools for Monitoring and Predicting the Ecotoxicological Effects of Chemicals in the Aquatic Environment

Effects of estuarine sediment contamination on feeding and on key physiological functions of the polychaete Hediste diversicolor: Laboratory and in situ assays.

Sediments have a major role in ecosystem functioning but can also act as physical or chemical stressors. Anthropogenic activities may change the chemical constituency of sediments and the rate, frequency, and extent of sediment transport, deposition, and resuspension. The importance of sediments as stressors will depend on site ecosystem attributes and the magnitude and preponderance of co-occurring stressors. Contaminants are usually of greater ecological consequence in human-modified, depositional environments, where other anthropogenic stressors often co-occur. Risk assessments and restoration strategies should better consider the role of chemical contamination in the context of multiple stressors. There have been numerous advances in the temporal and spatial characterization of stressor exposures and quantification of biological responses. Contaminated sediments causing biological impairment tend to be patchy, whereas more pervasive anthropogenic stressors, such as alterations to habitat and flow, physical disturbance, and nutrient addition, may drive large-scale ecosystem responses. A systematic assessment of relevant ecosystem attributes and reference conditions can assist in understanding the importance of sediments in the context of other stressors. Experimental manipulations then allow for the controlled study of dominant stressors and the establishment of causal links. This approach will result in more effective management of watersheds and waterways. Environ. Toxicol. Chem. 2010;29:2625–2643. © 2010 SETAC

https://setac.onlinelibrary.wiley.com/doi/pdf/10.1002/etc.332

Assessing contaminated sediments in the context of multiple stressors

Earthworms are important components of the soil system, mainly because of their favorable effects on soil structure and function (Paoletti 1999; Jongmans et al. 2003). Their burrowing and feeding activities contribute notably to increased water infiltration, soil aeration, and the stabilization of soil aggregates. In addition, earthworms help to increase soil fertility by formation of an organic matter layer in topsoil. These features, among others, have led to the popularity of earthworms as excellent bioindicators of soil pollution (Cortet et al. 1999; Lanno et al. 2004). These organisms ingest large amounts of soil, or specific fractions of soil (i.e., organic matter), thereby being continuously exposed to contaminants through their alimentary surfaces (Morgan et al. 2004). Moreover, several studies have shown that earthworm skin is a significant route of contaminant uptake as well (Saxe et al. 2001; Jager et al. 2003;Vijver et al. 2005).

Earthworm biomarkers in ecological risk assessment.

Marine mussels are useful, robust model organisms that have been widely used as biomonitors. In the natural environment they can be subjected simultaneously to a mixture of environmental stresses (hypoxia, starvation) and to pollutants. In this study Mytilus edulis was used to investigate the effects of two pesticides, atrazine and lindane, which have different modes of action but produce similar changes in behaviour (depression of ventilation and feeding) in the mussels, and can cause starvation and mild hypoxia. Acetonitrile/2H2O (60/40% v/v) extracts of foot muscle from animals subjected to hypoxia, or starvation, or low or high doses of pesticide were analysed using 1H NMR spectroscopy to produce metabolic fingerprints associated with these treatments. Discriminant analysis based on metabolites that showed significant differences between treated and control animals gave a clear separation between all treatment groups. The fingerprints of atrazine treated animals were clearly separated from those of animals that were starved or subjected to hypoxia. The high and low doses of atrazine were also well separated. Lindane treatment was separated from control animals in a dose dependent way, and was associated with an increase in the concentration of alanine, and a decrease in all of the other identified metabolites (including osmolytes). This is consistent with a general depression of activity. This limited study demonstrates the potential of the metabolomic approach to provide a separation of the effects of poisoning from those of environmental stress.

Delia F.N. Raymer

Papers

In situ exposures using caged organisms: a multi-compartment approach to detect aquatic toxicity and bioaccumulation