In the quest to monitor and understand freshwater fish diversity, scientists are increasingly turning to environmental DNA (eDNA) as a powerful tool. A recent study published in *Scientific Reports* sheds light on how eDNA compares to traditional morphological methods, offering insights that could reshape biodiversity assessments and benefit the agriculture sector.
The research, led by Yang Yu from the College of Water Conservancy at Shenyang Agricultural University, evaluated fish assemblages at 14 sites across six major rivers in Liaoning Province, China. The team employed four different primer sets—12S rRNA, COI, MiFish, and a high-variation MiFish—coupled with high-throughput sequencing, and compared the results with capture-based surveys. The findings revealed that eDNA detected a staggering 211 species across 17 orders, 71 families, and 146 genera, significantly outpacing traditional methods. However, eDNA also had its limitations, failing to identify nine species recorded morphologically and unable to provide ecological attributes such as body size or population structure.
“This study highlights the strengths and limitations of eDNA as a complementary tool to traditional methods,” said Yang Yu. “While eDNA offers a sensitive and efficient way to detect a wide range of species, it cannot replace the detailed ecological insights provided by morphological surveys.”
The research also found that species richness and composition varied between tributary and mainstem sites, reflecting hydrological and habitat gradients. Detection efficiency differed among primers, underscoring the importance of using multi-primer strategies for comprehensive assessments.
For the agriculture sector, the implications are significant. Accurate monitoring of fish diversity is crucial for maintaining healthy aquatic ecosystems, which in turn support agricultural productivity. Rivers and tributaries often serve as vital water sources for irrigation and livestock, making the health of these ecosystems directly relevant to farmers and agricultural businesses. By integrating eDNA and traditional methods, researchers can provide more accurate and timely data, enabling better management of water resources and aquatic habitats.
The study suggests that eDNA provides a sensitive and efficient complement to conventional surveys, but its limitations in taxonomic resolution and ecological inference highlight the need for integration of molecular and conventional morphological methods. This integrated approach could lead to more comprehensive fish diversity assessments, ultimately benefiting both ecological research and agricultural practices.
As the field of eDNA continues to evolve, this research paves the way for future developments in biodiversity monitoring. By combining the strengths of molecular and traditional methods, scientists and agricultural practitioners can work together to ensure the health and sustainability of freshwater ecosystems, supporting the broader goals of food security and environmental conservation.