Evaluating freshwater macroinvertebrates from eDNA metabarcoding: A river Nalón case study.

Area of Science:

• Environmental Science
• Molecular Biology
• Ecology

Background:

• Rivers are crucial for human well-being, necessitating effective management strategies.
• The European Union's Water Framework Directive (WFD) mandates sustainable water body protection.
• Benthic macroinvertebrates are key bioindicators, but conventional assessment methods face cost-efficiency limitations.

Purpose of the Study:

• To evaluate the reliability of metabarcoding for river macroinvertebrate assessment.
• To compare metabarcoding with conventional methods for freshwater quality monitoring.
• To assess the cost-benefit of using metabarcoding as a bioindicator tool.

Main Methods:

• In vitro validation using a mock community.
• Field validation using environmental DNA (eDNA) from six sites in the River Nalón, Spain.
• Amplification and sequencing of two markers (18S rDNA V4 and mitochondrial COI) on an Illumina platform.

Main Results:

• Metabarcoding demonstrated higher sensitivity compared to visual assessment methods.
• The study identified macroinvertebrate communities in river water samples.
• Cost-benefit analysis indicated metabarcoding is more expensive upfront but reduces sampling and identification efforts.

Conclusions:

• Metabarcoding is a sensitive and potentially valuable tool for assessing freshwater quality.
• This molecular technique offers an alternative to traditional bioindicator assessments.
• Further adoption of metabarcoding can enhance river health monitoring programs.