The use and misuse of biomarkers in ecotoxicology

Abstract

Substantial efforts have been devoted to developing and applying biomarkers for use in ecotoxicology. These efforts have resulted partly from a desire for early warning indicators that respond before measurable effects on individuals and populations occur and partly as an aid to identifying the causes of observed population- and community-level effects. Whereas older biomarkers focused on measures of organism physiology or biochemistry, advances in molecular biology are extending the biomarker philosophy to the level of the genes (i.e., ecotoxicogenomics). However, the extent to which biomarkers are able to provide unambiguous and ecologically relevant indicators of exposure to or effects of toxicants remains highly controversial. In the present paper, we briefly discuss the application of biomarkers in ecotoxicology and ecological risk assessment, and we provide examples of how they have been applied. We conclude that although biomarkers can be helpful for gaining insight regarding the mechanisms causing observed effects of chemicals on whole-organism performance and may, in some cases, provide useful indicators of exposure, individual biomarker responses should not be expected to provide useful predictions of relevant ecological effects--and probably not even predictions of whole-organism effects. Suites of biomarkers are only likely to provide increased predictability if they can be used in a comprehensive mechanistic model that integrates them into a measure of fitness. Until this can be achieved, biomarkers may be useful for hypothesis generation in carefully controlled experiments. However, because the aims of environmental monitoring and ecological risk assessment are to detect and/or predict adverse chemical impacts on populations, communities, and ecosystems, we should be focusing our efforts on improving methods to do this directly. This will involve developing and testing models of appropriate complexity that can describe real-world systems at multiple scales.

Key metabolic pathways involved in xenobiotic biotransformation and stress responses revealed by transcriptomics of the mangrove oyster Crassostrea brasiliana

“…However, along with other Ostreidae species, little is known regarding the specific genomic and transcriptomic adaptations to these contaminants. The monitoring endpoints are based on a small number of biomarkers with origins in human toxicology, and are therefore not bivalve-specific (Forbes et al, 2006). In excess of the ecological and economical importance of oysters to the coastal areas and the aquaculture industry, understanding their biology, susceptibility to pollutants and differential stress resistance has become an important issue for modern ecotoxicology.…”

A manipulative field experiment to evaluate an integrative methodology for assessing sediment pollution in estuarine ecosystems

“…The aims of environmental monitoring and risk assessment are to detect and/or predict adverse chemical impacts on populations, communities and ecosystems (Forbes et al, 2006). These results suggest that this methodology may be regarded as a reliable tool for assessing and monitoring pollution in estuarine areas.…”

“…Since the aims of environmental monitoring and ecological risk assessment are to detect and/or predict adverse chemical impacts on populations, communities and ecosystems (Forbes et al, 2006), the establishment of any relationship between disturbance and benthic assemblages in the field is a first and necessary step towards understanding environmental impact (Underwood and Peterson, 1988). Accordingly, the use of epidemiological approach is becoming a powerful method for increasing the certainty concerning causal claims (Adams, 2003).…”

Laboratory-to-Field Extrapolation in Aquatic Sciences

“…For trace elements (we are aware that research is at a more advanced stage for organic contaminants), induction of many biomarkers in aquatic invertebrates occurs at concentrations 1-2 orders of magnitude higher than typical environmental levels (32,33). Unless these kinds of discrepancies are quickly solved, extrapolation of many laboratory results to the field will remain very problematic (34,35), despite the unquestionable scientific rigor of the cited (and other similar) studies.…”