Beyond Exponential Decay: How Biphasic and Delayed Decay Dynamics Shape Marine eDNA Dispersal

Area of Science:

• Marine biology
• Environmental science
• Molecular ecology

Background:

• Accurate interpretation of marine environmental DNA (eDNA) monitoring relies on understanding eDNA concentration changes after release.
• Many studies default to a single-phase exponential decay model, despite evidence for complex patterns like biphasic and delayed decay.

Purpose of the Study:

• To investigate the impact of different eDNA decay patterns on marine eDNA dispersal.
• To quantify how biphasic and delayed decay dynamics affect eDNA concentrations compared to exponential decay.
• To assess the implications for marine eDNA monitoring and transport models.

Main Methods:

• Conducted a literature review of empirical eDNA decay experiments.
• Performed an experimental study to determine empirical decay patterns at different temperatures.
• Utilized high-resolution Lagrangian particle tracking to model eDNA dispersal.

Main Results:

• Over half of reviewed studies and experimental data (at 13°C and 20°C) showed biphasic or delayed eDNA decay patterns.
• The initial 12 hours post-release are critical for identifying biphasic or delayed decay dynamics.
• Alternative decay dynamics increased eDNA concentrations by 2-4 times after 24 hours compared to exponential decay.

Conclusions:

• Non-exponential decay patterns (biphasic, delayed) are common and significantly alter eDNA concentrations.
• Assuming exponential decay can lead to substantial under- or overestimation of eDNA release, impacting monitoring accuracy.
• Incorporating appropriate eDNA decay types is essential for accurate marine eDNA transport modeling and data interpretation.