Slimy, salivary guffe spreads on the seabed in Norway
This article is produced and funded by Norwegian Institute for Natural Research – read more.
The unwanted alien species has the disgusting name harbor spear. Researchers use environmental DNA to map the spread in Norwegian ports.
Spread of alien species is considered one of the greatest threats to biodiversity worldwide.
Havnespy is not an official Norwegian name for the species Didemnum vexillum, but is directly translated from the English nickname «sea vomit». Havnespy is also known as the Japanese sea urchin, and is one of the worst among alien species.
It spreads rapidly and forms fast-growing colonies that suffocate all life on the seabed, where it establishes itself.
In 2020, harbor spews were discovered for the first time in Norway, in Engøysundet in Stavanger.
Since then, it has also been detected in Haugesund, outside Bergen and in Egersund.
Water samples in each port
Ship traffic is an important dispersal route for marine alien species, and marinas with a lot of international traffic are particularly vulnerable.
– Once the harbor spew has established itself in an area, it is impossible to get rid of it. Therefore, it is very important to limit further spread. This presupposes that we know where the species already exists, says Frode Fossøy, geneticist and senior researcher at NINA.
As before Christmas, employees at NINA collected over 100 water samples from the largest ports between Stavanger and Bergen to look for harbor spews on behalf of the Norwegian Environment Agency.
Sampling was performed within five days as a so-called rapid response analysis. The samples were then re-analyzed at NINA’s tick lab in Trondheim.
– We got results on all localities where harbor spit had already been detected earlier. This shows that environmental DNA is a good method for mapping distribution and monitoring spread, says Fossøy.
Recommends national mapping
In addition to the known deposits, the DNA analyzes showed harbor spit at three locations in Brandangersundet in Gulen municipality. These samples had relatively low DNA concentrations.
This may indicate a recent establishment of art in the area.
Havnespy has not previously been detected so far north in Norway. But the find also represents the northernmost locality in NINA’s survey.
The researchers can therefore not say anything about the prevalence of harbor spews based on this study, but recommend that the survey be continued with sampling from the Sognefjord and northwards for a complete, national survey.
Like finding the needle in the haystack
This is the first time that environmental DNA has been used to map harbor spews in Norway. And despite the fact that the findings themselves are disappointing, the results give cause for optimism.
– The Norwegian coast is long. Environmental DNA is a cost-effective and accurate method that makes it possible to needle in the haystack with little effort. Early detection of alien species is a prerequisite for being able to implement the right measures, says Fossøy.
Mapping using environmental DNA is both easier, faster and cheaper than other methods. Positive fun can be followed by traditional felting methods to see the distribution and size of the colonies.
Reference:
Frode Fossøy and others: Mapping of the alien marine species harbor spear Didemnum vexillum using environmental DNA. A quick response survey. NINA Report2022