Sampling Designs for Landscape-level eDNA Monitoring Programs

Area of Science:

• Ecology
• Environmental Science
• Conservation Biology

Background:

• Accurate species distribution data is crucial for natural resource management.
• Environmental DNA (eDNA) analysis is a key method for species detection and distribution mapping.
• Imperfect detection in sampling and molecular analysis can impact eDNA-based distribution estimates.

Purpose of the Study:

• To quantify imperfect detection in environmental DNA (eDNA) studies for rare and common species.
• To determine optimal sample sizes for detecting eDNA and estimating capture parameters.
• To evaluate the performance of a three-level occurrence model for eDNA data.

Main Methods:

• Examined multiple field capture and detection probabilities.
• Assessed sample size requirements for eDNA detection and parameter estimation.
• Investigated the performance of a three-level occurrence model under varying detection probabilities.

Main Results:

• Detecting common species eDNA required ≤15 samples per site.
• Detecting rare species eDNA required 45–90 samples per site.
• The occurrence model performed well unless detection probabilities were <0.2, necessitating >100 samples and ≥8 molecular replicates.

Conclusions:

• Sample size and molecular replication are critical for robust eDNA-based species distribution studies.
• Understanding detection probabilities is essential for accurate eDNA data interpretation.
• The findings provide guidance for optimizing eDNA sampling strategies in conservation and management.