Freshwater fish community assessment using eDNA metabarcoding vs. capture-based methods: Differences in efficiency...

Area of Science:

• Ecology
• Environmental Science
• Molecular Biology

Background:

• Environmental DNA (eDNA) metabarcoding offers a non-invasive approach to biodiversity monitoring.
• Comparing eDNA metabarcoding with traditional methods like electrofishing is crucial for its adoption in long-term monitoring programs.

Purpose of the Study:

• To compare the effectiveness of eDNA metabarcoding and electrofishing for assessing freshwater fish communities.
• To evaluate data comparability between the two methods in the lower Tagus River basin.

Main Methods:

• Conducted sampling at 35 sites in the lower Tagus River basin, Portugal.
• Assessed freshwater fish communities using both eDNA metabarcoding and electrofishing.
• Analyzed species detections, specimen counts, species richness, and community composition.

Main Results:

• A significant correspondence was found between electrofishing and eDNA detections for most species (13/17).
• Species richness estimates were similar between methods at the basin level.
• Species composition differed significantly, particularly in the main river channel, likely due to hydrological factors and method-specific efficiencies.

Conclusions:

• eDNA metabarcoding shows high potential as a complementary tool to electrofishing for freshwater fish monitoring.
• Further validation is needed to address biases related to hydrological conditions and species ecology.