Recreational boat traffic leaves clear traces in the environment. It is now clear after the Marine Environment Institute examined bottom sediments, mussels and oysters in the Bohuslän archipelago.
In a new report, researchers have for the first time examined the extent to which exhaust fumes from recreational boat traffic are stored in the seabed and aquatic organisms. And the result is clear: the levels of polyaromatic hydrocarbons (PAH), which are toxic and can contribute to cancer, are five times higher in surface sediments in areas such as Grebbestad and Tanumstrand, where boat traffic is dense, compared to, for example, adjacent Sannäs, which has significantly less boat traffic.
“There is every reason to phase out petrol and diesel-powered boat engines,” says Kjell Nordberg, professor of marine sciences at the University of Gothenburg, in a press release from the Institute of Marine Environment, a collaboration between several large Swedish universities.
Sensitive areas
One of the problems for the Swedish archipelago is that it is more sensitive than other waters as the tidal currents are weak. When the water flow is low in the inner archipelago, pollutants are more easily left in sediments, plants and animals.
But at the same time, there are major common economic interests in Bohuslän’s waters. In addition to boat tourism, there is aquaculture with mussel and algae farms, which is a new growing economy. But there are conditions to coexist, as long as you do not grow and harvest in where boat traffic is most intense.
“Not alarming”
However, Kjell Nordberg believes that it may be good to think about where mussel farms are located in the future:
“Even if we do not see anything alarming right now, there is every reason to call for caution with petrol and diesel-powered boat engines. We recommend continued work to reduce the levels of PAHs in the sea through, for example, general speed limits and stimulation of electric motors and sailing, “he says in the press release.