Amazing new research has shown that we can detect what species of fish are found in different parts of our seas simply by collecting samples of the local seawater. The key to identifying which species are present is in traces of DNA - known as environmental DNA (eDNA) - which are left in the surrounding water by fish that pass through. Just half a litre of seawater from a temperate marine ecosystem in Denmark provided DNA fragments from 15 different fish species, including some that were rarely recorded by more invasive conventional methods, as well as 4 bird species. Experiments show that even small fragments of eDNA degrade to the point that they are no longer detectable within days, suggesting that the method gives an up-to-date and accurate recording of the species that inhabit the area at that point in time. A further study looking into the possibility of marine mammal detection using the eDNA method suggests that greater volumes of seawater are needed to be analysed in order to detect them, but that eDNA has the potential to support current visual and acoustic methods of species detection for marine mammals as well as fish.
Ref: Thomsen P. F. et al., 2012. Detection of a diverse marine fish fauna using environmental DNA from seawater samples. PLOS One [link]
Foote A. D. et al., 2012. Investigating the potential use of environmental DNA (eDNA) for genetic monitoring of marine mammals. PLOS One [link]