eDNA in the Serchio River: 62 vertebrate taxa found

Researchers at the University of Florence and the University of Pisa applied environmental DNA (eDNA) metabarcoding to the Serchio River basin in Tuscany, central Italy, and identified 62 vertebrate taxa, according to a study in Water Biology and Security doi.org. The basin is understudied and includes heterogeneous environments, from mountain streams to lowland reaches doi.org.

Sampling and results

The team took water samples at five strategic areas, in rivers of different sizes within each area. The samples were filtered, and eDNA was extracted from them. The identified taxa represent the major vertebrate classes present in these rivers: fish, amphibians, reptiles, birds and mammals. They include both protected species and invasive alien species doi.org.

The observed distribution patterns matched ecological expectations, namely known habitat preferences and longitudinal river zonation doi.org. According to the authors, eDNA metabarcoding characterized the basin's biodiversity in a relatively short time compared with traditional methods and captured the gamma diversity of the area. The data are qualitative: they show the occurrence of aquatic and terrestrial vertebrates doi.org.

DNA traces of Lampetra (lamprey) were detected, a genus with no historical record in the Serchio basin. The authors also reported a significant correlation between the number of European eel DNA reads and the number of dams between sampling sites and the estuary doi.org.

Comparison with traditional monitoring

The eDNA results were compared with traditional monitoring: transect surveys conducted between March 2021 and October 2023, and electrofishing sessions. In all areas eDNA detected more species, including taxa not strictly associated with the river system. Both approaches, however, also identified some unique taxa doi.org.

Taxa counts were generally higher in the mainstem than in smaller tributaries, which suggests that eDNA accumulates in the main river branches. The authors say this points to the potential of focusing on mainstem courses for more efficient biodiversity monitoring at the basin scale doi.org.

The authors note that traditional monitoring in lotic environments is often invasive, requires specific expertise and involves specimen handling that can lead to organism mortality. eDNA metabarcoding is a non-invasive alternative based on genetic material that organisms naturally shed doi.org.

eDNA metabarcoding in Italy's Serchio River basin identified 62 vertebrate taxa, more than traditional surveys

Sampling and results

Comparison with traditional monitoring

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