PhD student Philip Francis Thomsen is |
Danish
researchers at University of Copenhagen are showing the way for future
monitoring of marine biodiversity and resources by using DNA traces in
seawater samples to keep track of fish and whales in the oceans. A half
liter of seawater can contain evidence of local fish and whale faunas
and combat traditional fishing methods. Their results are now published
in the international scientific journal PLOS ONE.
“The
new DNA method means that we can keep better track of life beneath the
surface of the oceans around the world, and better monitor and protect
ocean biodiversity and resources,” says PhD student Philip Francis
Thomsen from the Centre for GeoGenetics, Natural History Museum of
Denmark, University of Copenhagen.
Marine
ecosystems worldwide are under threat with many fish species and
populations suffering from human over-exploitation, which greatly
impacts global biodiversity, economy and human health. Today, marine
fish are largely surveyed using selective and invasive methods mostly
limited to commercial species, and restricted to areas with favorable
conditions.
However,
researchers at Centre for GeoGenetics now lead the way for future
monitoring of marine biodiversity. They have shown that seawater
contains DNA from animals such as fish and whales. The species leave
behind a trace of DNA that reveals their presence in the ocean based on
water samples of just half a liter.
From freshwater to seawater
The
development of the novel DNA monitoring approach was accomplished by
PhD student Philip Francis Thomsen and Master’s student Jos Kielgast
from the Centre for GeoGenetics headed by Professor Eske Willerslev. In
December last year, they showed that small freshwater samples contain
DNA from several different threatened animals, and after having
published these results they began to focus on seawater. Here it also
proved possible to obtain DNA directly from the water, which originated
from local species living in the area.
“We
analyzed seawater samples specifically for fish DNA and we were very
surprised when the results started to show up on the screen. We ended up
with DNA from 15 different fish species in water samples of just a half
litre. We found DNA from both small and large fish, as well as both
common species and rare guests. Cod, herring, eel, plaice, pilchard and
many more have all left a DNA trace in the seawater,” says Philip
Francis Thomsen.
In
the other study the researchers showed that it is also possible to
obtain DNA from harbor porpoise in small water samples taken in the
sea, so the approach is not only limited to fish, but can also track
large marine mammals.
A new and efficient method
The
study also compares the new DNA method with existing methods
traditionally used for monitoring fish such as trawl and pots. Here, the
DNA method proved as good as or mostly better than existing methods.
Moreover, the DNA method has a big advantage that it can be performed
virtually anywhere without impacting the local habitat—it just requires a
sample of water. Associate Professor and fish expert Peter Rask Møller
from the National History Museum of Denmark, who also participated in
the study, is optimistic.
“The
new DNA method has very interesting perspectives for monitoring marine
fish. We always keep our eyes open for new methods to describe marine
fish biodiversity in an efficient and standardized way. Here, I look
very much forward to follow the DNA method in the future, and I think it
could be very useful to employ in oceans around the world,” says Peter
Rask Møller.
The researchers also see great perspectives in the method for estimating fish stocks in the future.
Detection of a Diverse Marine Fish Fauna Using Environmental DNA from Seawater Samples
Investigating the Potential Use of Environmental DNA (eDNA) for Genetic Monitoring of Marine Mammals
Source: University of Copenhagen
