Biomarkers in Invertebrates

Abstract

Invertebrates offer a number of advantages for in situ measurement using animal biomarkers. Their ability to colonize many different compartments of terrestrial and aquatic ecosystems mainly result from both the development of various strategies for resource exploitation and a high biotic potential as expressed by fast growth and high reproduction rates for most species. Due to their position at different levels in food webs, invertebrates play functional key-roles in ecosystems and when affected by chemicals, they can be responsible for dramatic changes in community structure and function. Therefore, they display a great potential for evaluating the ecological impact of pollutants. Adaptability is probably a key-feature of invertebrates in heavily deteriorated environments. Invertebrates can thus be found in highly polluted habitats where vertebrates are virtually absent. In this case, they frequently represent the only way to evaluate the effects of pollutants on animal biological systems. Biomarkers measured in invertebrates allow diagnosis of long-term effects of chemicals. The development of resistance to toxic chemicals, physiological adaptation involving changes in metabolic energy allocation, occurrence of morphological or anatomical abnormalities, are situations in which changes induced by long-term exposure of the individuals have consequences on population structure and dynamics. Biomarkers measured at the individual level may thus be linked with population changes from which further impact on community structure and function may be expected. Such an approach can be used to classify polluted areas according to the level of ecological damage in order to identify priority cases for remediation. The same biomarkers can then be used as early signs of biological restoration of damaged ecosystems. For example, enzymatic biomarkers can indicate decreased levels of resistance within exposed populations as a result of decreased selection pressure on individuals. Similarly, changes in energy allocation, as assessed through individual evaluation of scope for growth and scope for reproduction, can occur as a response to better environment conditions and may result in changes in population dynamics. Measurement of biomarkers in invertebrates certainly provide valuable information on both the ecological impact of long-term chemical contamination (diagnostic approach) and the conditions of biological restoration of damaged ecosystems (predictive approach). Both approaches however require a pertinent choice of invertebrate species and the assessment of linkable responses at different levels of biological organisation.