Improving the selection of focal species exposed to pesticides to support ecological risk assessments
Résumé
Risk assessment investigates the potential
impacts of chemicals on non-target organisms. To assess
the risk, ecotoxicologists study the responses of a panel of
species to different substance exposure. Among the different
parameters used to select indicator species (i.e. focal
species), their frequency of occurrence is considered as the
key parameter. Although species occurrence within a given
habitat is easy to determine, we argue that it does not
totally reflect the dependence of a species on a given
habitat or its potential exposure to chemicals. In this study,
we combined the occurrence of species with their habitatspecificity
to identify focal species for risk assessment in
cereals. We showed that ranking species by occurrence or
by habitat-specificity produced different results, with generalist
species ranking high in the occurrence list, and
species with specialised habitats ranking high in the
abundance list. Integrating frequency and abundance of
species into one single indicator (the ‘‘Indicator Value’’)
allows us to rank species with specialised habitats as high
as generalist species in the top rank species list. Although
habitat-specificity is an ecologically meaningful concept, it
is largely overlooked in eco-toxicological risk assessment,
despite the fact that specialists are good indicators of various
environmental pressures. This method could be used
extensively at different scales and could contribute to
studies on risk assessment issue by (re)introducing ecological
and population-level concepts and opening up new
trait-based approaches.