Intraspecific genetic variability and diurnal activity affect environmental DNA detection in Japanese eel

Area of Science:

• Aquatic Ecology
• Molecular Ecology
• Environmental Monitoring

Background:

• Environmental DNA (eDNA) analysis offers a promising, non-invasive method for quantifying fish populations.
• Accuracy of eDNA methods can be compromised by biological factors like genetic variation and organism behavior.

Purpose of the Study:

• To investigate the influence of intraspecific genetic variability on eDNA detection sensitivity in Japanese eels (Anguilla japonica).
• To assess the impact of diel activity rhythms and inter-individual differences on eDNA concentration and detection.

Main Methods:

• Tank experiments were conducted to analyze eDNA detection across Japanese eel individuals.
• Genetic sequencing identified polymorphisms in probe regions, and eDNA concentrations were measured.
• Rearing experiments monitored eDNA release in relation to diel activity and individual variation.

Main Results:

• Genetic mismatches in probe regions of two individuals correlated with significantly lower eDNA concentrations.
• Nocturnal activity patterns of eels influenced eDNA detection, but substantial inter-individual differences persisted.
• Weak positive correlations between eDNA concentration and activity suggest a link to basal metabolism.

Conclusions:

• Polymorphic sites within primer/probe regions can affect eDNA detection accuracy.
• Diel activity rhythms and individual metabolic rates influence eDNA shedding, impacting abundance estimations.
• Refining eDNA methodologies by considering genetic variation and behavioral patterns is crucial for accurate fish monitoring.