What do sentinels stand for?

Area of Science:

• Environmental Science
• Ecotoxicology
• Biomonitoring

Background:

• Sentinel species accumulate pollutants, serving as biological monitors for environmental contamination.
• Their primary use is measuring pollutant bioavailability and simplifying complex pollution signals.
• Invertebrates are frequently used for monitoring toxic metal pollution in terrestrial ecosystems.

Purpose of the Study:

• This paper examines the validation process for sentinel species in monitoring toxic metal pollution.
• It specifically addresses the use of invertebrates in terrestrial ecosystems.
• The study aims to clarify definitions of bioavailability and species-specific responses.

Main Methods:

• The study reviews the requirements for validating sentinel species, including temporal and spatial scales of integration.
• It emphasizes the need for calibration against source concentrations and consistent relationships.
• Consideration of environmental and biological determinants of pollutant assimilation is highlighted.

Main Results:

• Few studies adequately measure a sentinel's capacity to quantify ambient pollution level changes.
• Bioavailability definitions vary, and species-specific measures are often overlooked.
• Differences in native populations can complicate site comparisons; transplantation may be necessary.

Conclusions:

• A simple measure is proposed to evaluate candidate sentinel species' consistency and equilibration capacity.
• Interpreting tissue concentrations requires understanding pollutant assimilation determinants.
• The study illustrates challenges using earthworms in lead (Pb) pollution gradients.