Population level effects ecotoxicology

Forbes, V.E. and Calow, P. (1999). Is the per capita rate of increase a good measure of population-level effects in ecotoxicology Environmental Toxicology and Chemistry 18, 1544-1556. 

Caswell H. 1996. Demography meets ecotoxicology untangling the population level effects of toxic substances. In Newman MC, Jagoe CH, editors. Ecotoxicology a hierarchical treatment. Boca Raton (FL) Lewis Publishers, p 255-292. 

Apart from the use of this approach to study the ecotoxicology of neurotoxic pollutants in the field, it also has potential for use during the course of environmental risk assessment. An understanding of the relationship between biomarker responses to neurotoxic compounds and effects at the population level can be gained from both field studies and the use of mesocosms and other model systems. From these it may be possible to define critical thresholds in biomarker responses of indicator species above which population effects begin to appear. In the longer term, this approach... 

Invertebrate ecotoxicology is a specialized area of ecotoxicology that deals with all aspects of ecological and toxicological effects of toxic substances on invertebrates and their consequences at the population level and above. The main objectives of invertebrate ecotoxicology are similar to those of ecotoxicology itself, related to the areas where invertebrates can be used ... 

Barnthouse, L.W., G.W. Suter, II, and A.E. Rosen. 1989. Inferring population-level significance from individual-level effects an extrapolation from fisheries science to ecotoxicology. In Aquatic Toxicology and Environmental Fate, Vol. 11, ASTM STP 1007. G.W. Suter, II and M.A. Lewis, Eds. American Society for Testing and Materials, Philadelphia, PA, pp. 289-300. 

Dalkvist T, Topping CJ, Forbes VE. 2009. Population-level impacts of pesticide-induced chronic effects on individuals depend more on ecology than toxicology. Ecotoxicology and Environmental Safety doi 10.1016/j.ecoenv.2008.10.002. Available from http // dx.doi.org/10/1016/j. ecoenv.2008.10.002. 

Ecotoxicology deals with the study of the harmful effects of chemicals in ecosystems. This includes harmful effects upon individuals, although the ultimate concern is about how these are translated into changes at the levels of population, commnnity, and ecosystem. Thns, in the conclnding sections of the chapter, emphasis will move from the distribntion and environmental concentrations of pollutants to conseqnent effects at the levels of the individnal, population, community, and ecosystem. The relationship between environmental exposure (dose) and harmful effect (response) is fundamentally important here, and full consideration will be given to the concept of biomarkers, which is based on this relationship and which can provide the means of relating environmental levels of chemicals to consequent effects npon individuals, populations, communities, and ecosystems. 

The text is divided into three parts. The first deals with the basic principles underlying the environmental behavior and effects of organic pollutants the second describes the properties and ecotoxicology of major pollutants in reasonable detail the last discusses some issues that arise after consideration of the material in the second part of the text, and looks at future prospects. The groups of compounds represented in the second part of the book are all regarded as pollutants rather than simply contaminants, because they have the potential to cause adverse biological effects at realistic environmental levels. In most cases these effects have been well documented under environmental conditions. The term adverse effects includes harmful effects upon individual organisms, as well as effects at the level of population and above. 

Interaction effects of mercury with other contaminants, such as herbicides and pesticides, could intensify hazards to avian populations (Mullins et al. 1977). For example, a striking parallel exists between levels of Hg and of DDT and its metabolites in birds of prey, suggesting the existence of common ecotoxicological mechanisms (Delbeke et al. 1984 Wiemeyer et al. 1984) additional research is clearly needed. 

We have reviewed current conceptual and modeling approaches in mixture eco-toxicology as well as current experimental evidence to derive practical risk assessment protocols for species and species assemblages. From the review of conceptual approaches in mixture ecotoxicology, it appears that there is a difference between a mechanistic view of joint action from a compound mixture and a probabilistic perspective on combined toxicity and mixture risk. A mechanistic view leads to emphasis on the distinction of modes of action and physicochemical properties first, then on the choice of the appropriate joint toxicity model, followed by a comparison of the models prediction with experimental observations. A probabilistic orientation leads to the observation that concentration addition often yields a relatively satisfactory quantitative prediction of observations for the integral level of effects as observed in individual organisms or populations. In these applications, concentration addition is frequently connected with a slight bias to conservatism, especially for compounds with different modes of action (Backhaus et al. 2000,2004 Faust et al. 2003). 

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