From the marina – University of Copenhagen

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24 May 2017

From the marina

MOLECULAR LEFT-OVERS

In a recent study published in Marine Biology, researchers from CGG and the Natural History Museum of Denmark have shown that environmental DNA (eDNA) from seawater samples can reflect the seasonal movements of local fish species.

Associate Professor Peter Rask Møller and collegues collected fish DNA from lose coastal waters and compared it with the fish they actually saw. (Photo: Eva Egelyng Sigsgaard).

Associate Professor Peter Rask Møller and collegues collected fish DNA from coastal waters and compared it with the fish they actually saw. (Photo: Eva Egelyng Sigsgaard).

“We show that the composition of the eDNA changes gradually and cyclically throughout the year, like the fish community, and reflects the migratory behavior of the fishes. While sturdy species such as eelpout were found in the eDNA throughout the year, migrants like the garfish only appeared in the eDNA in spring and summer“, says PhD-student Eva Egelyng Sigsgaard, first author of the study.

She explains: “So far, in the marine eDNA research on macro-organisms, only short-term intervals have been observed so we have not known how the eDNA in the ocean changed over time. However, our study shows that the eDNA composition follows the seasonal movements of fishes. The results indicate that eDNA could be used to monitor changes in marine ecosystems as a result of, for instance, climate change.”

Assistant Professor Philip Francis Thomsen from the Centre for GeoGenetics, who led the study, says:

"That the eDNA signal varies over the seasons - and that this variation follows the biology of the fishes - is a prerequisite for the method to be used for monitoring of marine biodiversity. If the eDNA levels were more static throughout the year, they would not be able to tell us anything about rapid changes occurring in the fauna due to e.g. climate and seasons."

Every second week for a year the researchers sampled for eDNA. (Photo: Eva Egelyng Sigsgaard).

Every second week for a year the researchers sampled for eDNA. (Photo: Eva Egelyng Sigsgaard).

Associate Professor Peter Rask Møller from the Natural History Museum of Denmark and head of the Atlas of Danish Fishes project (funded by the Aage V. Jensen Foundations) elaborates:

This is the first time anyone has surveyed a fish fauna for a full year using eDNA, and the first time that snorkeling has been used for fish surveillance at our latitudes. So far, snorkeling has been considered a tropical method. The two methods confirmed each other in this study as they largely found the same species. Following the dynamics of a Danish marine fish community over a year is also in itself a rarity. The project has benefited from the knowledge and tissue samples we have collected in the Atlas project on Danish saltwater fishes and shows how different methods can work together to improve the knowledge of our coastal nature - which is more overlooked than you would think."

Sigsgaard et al.: Seawater environmental DNA reflects seasonality of a coastal fish
community. Marine Biology, (2017) 164:128. DOI 10.1007/s00227-017-3147-4