Special issue on long-term ecotoxicological effects: an introduction

Abstract

Two years after the Special Issue published in JournalEcotoxicology on Evolutionary Process in Ecotoxicology(vol 20 (3); see Coutellec and Barata 2011), the presentissue proposes a timely update on long-term biologicalimpacts of pollutants, including delayed, trans-genera-tional, and evolutionary effects. The number of articlescontributed in the present issue confirms that this questionis gaining ground in the field of ecotoxicology. Despite theawareness of the scientific community that evolutionarychange can occur rapidly (e.g., Carroll et al. 2007), and thataddressing the long term ecotoxicological impact is rele-vant to improve the significance of ecological risk assess-ment of chemicals (e.g., Bickham 2011), this research fieldhas been poorly explored until recent time. Most often,long term trans-generational or evolutionary responses topollution have been limited to experimental studies basedon model species appropriate to multi-generation exposure(primarily waterflea or other short-lived invertebrates) andto molecules with some knowledge or expectation on theirmode of action (e.g., metals, candidate genes involved intolerance and adaptation). While these remain undeniablysound models, current advances in molecular technologyallow tackling long term trans-generational or evolutionaryeffects under more realistic conditions, involving naturalecosystems, presence of multistressors in the field, andusing species of particular ecological relevance (includinglonger-lived species), or by tracing back evolutionaryprocesses in wild populations (see van Straalen and Feder2012).Long-term effects of pollutants: inferring causativerelationshipsOne recurrent problem in assessing the evolutionary impactof a given chemical is that cause-effect relationships arestill extremely difficult to determine in the field, as manyfactors can be responsible for an observed pattern of neu-tral or selectable genetic variation. Nevertheless, we simplycannot ignore such impact just because it is difficult toassess. The current endeavor of scientists towards fillingthis gap is further motivated by the fact that the environ-ment needs to be considered in its changing nature (i.e.,with regard to climate or biological invasions). The ever-increasing demand imposed by humans on natural resour-ces also requires that some trade-off can be reachedbetween human impact and conservation (see Bijlsma andLoeschcke 2012). Reliable tools are needed to enabledecision makers to apply conditions under which this trade-off could be optimized in order to ensure a sustainable useand management of ecosystems and resources. This isclearly a new challenge, and in this respect, long-term andevolutionary ecotoxicology represents a building block ofsuch a strategy, providing concepts and tools with bothindicative and predictive value, that could be implementedin environmental risk assessment (see also Breitholtz et al.2006; Bickham 2011).In the present issue, long-term effects of pollutants areeither documented under natural situations or tested usingexperimental designs, and some contributions combined