Tracking an invasion front with environmental DNA

Area of Science:

• Ecology
• Environmental Science
• Molecular Biology

Background:

• Environmental DNA (eDNA) shows promise for ecological monitoring, but its integration into management decisions is limited by interpretation uncertainties.
• Traditional methods like trapping are established for species management but can be labor-intensive and less sensitive.
• Invasive European green crab (Carcinus maenas) management historically relies on trapping, necessitating evaluation of new monitoring tools.

Purpose of the Study:

• To develop and validate a joint modeling framework integrating eDNA and traditional trap data for invasive species density estimation.
• To quantify the uncertainty associated with both eDNA and trap detection methods.
• To assess the added value of eDNA data in enhancing existing monitoring programs for management.

Main Methods:

• Jointly modeling quantitative PCR (qPCR) eDNA detection and traditional trap data.
• Estimating the density of European green crab (Carcinus maenas).
• Analyzing the marginal information benefit of incorporating eDNA data into monitoring.

Main Results:

• Documented European green crab eDNA presence beyond the known invasion front.
• Demonstrated that eDNA data value increases significantly with low population densities and reduced traditional sampling effort.
• Identified detection limits of the molecular assay and scenarios where eDNA may not improve management.

Conclusions:

• A joint modeling approach provides a robust method for integrating diverse data streams in environmental management.
• eDNA sampling is particularly valuable for detecting species at the leading edge of invasions.
• Understanding assay limitations and integration scenarios is crucial for optimizing eDNA's role in conservation and management.