Eyeing DNA barcoding for species identification of fish larvae

Area of Science:

• Marine Biology
• Genomics
• Taxonomy

Background:

• Morphological identification of fish larvae is challenging and time-consuming, often limited to higher taxonomic ranks.
• High-throughput DNA sequencing offers a potential solution for efficient and precise larval identification.

Purpose of the Study:

• To implement and evaluate a reverse workflow using nanopore sequencing for DNA barcoding and sorting of fish larvae.
• To assess the efficiency and success rate of this molecular approach for fish larvae identification in Singapore.

Main Methods:

• Collected 3022 fish larval specimens from plankton tows in Singapore.
• Extracted DNA from eye tissue and sequenced the cytochrome c oxidase subunit I gene using nanopore sequencing.
• Utilized a reverse workflow for specimen sorting and identification into molecular operational taxonomic units (mOTUs).

Main Results:

• Successfully generated 2746 DNA barcodes with a 90.9% barcoding success rate.
• Identified 2067 DNA barcodes with a 75.3% identification success rate, delimiting 256 mOTUs.
• Identified challenges in species assignment due to reference database quality and proposed using local databases to resolve conflicts.

Conclusions:

• The proposed DNA barcoding workflow significantly expedites taxonomic identification of fish larvae.
• This approach enhances reference barcode databases and aids in understanding fish connectivity.
• Leveraging molecular techniques reduces reliance on laborious morphological sorting, freeing up expert taxonomists for complex species-level work.