The Sound is located between Sweden and Denmark, and forms, together with Little Belt and Great Belt, a connection between the brackish Baltic Sea and the saltier North Sea via Kattegat and Skagerrak. The layering of the water column is strong. The outflowing water from the Baltic Sea towards Kattegat has a low salinity at 10 psu, putting the relatively lighter water at the surface. The saltier water from Kattegat, at 20 psu, is heavier and runs to the Baltic Sea in a south-going bottom stream. A transverse threshold which is found at less than 10 meters deep at the narrow part in the south of the Sound, acts as a barrier to water exchange between the Baltic Sea and Kattegat. In 1932, a bottom trawling ban was established in the Sound because of the heavy traffic in the narrow strait. The ban, which is still in effect, is one of the main reasons behind the number of rare and diverse benthic communities found in the area today.
The Sound is home to many benthic communities, including soft bottom communities like Haploops, Modiolus, Amphiura, eelgrass, and sea pens with burrowing megafauna. Regular sampling has shown that the Haploops community is declining in the Sound, and there only are few stable populations registered in a restricted area north of Ven island. Also horse mussels have had a similar decrease in the Sound. The Modiolus beds are considered as vulnerable by HELCOM. The northern part of the Sound is an important area for harbour porpoise (Phocoena phocoena), where they gather in high numbers during the breeding season in the spring and summer.
The Sound’s unique set of species and communities, and the concerning state of some of the life it supports, make it a prime area for protection. Our findings support the view that in order to save the last remnants of the Haploops and Modiolus communities, as well as other important communities and species present in the Sound, it should be protected from all forms of impacts to the seafloor.
Oceana has been making fieldwork in the Sound in 2011, 2012 and 2013 with ROV, divers and bottom samples.
There is a local wish to protect the Sound. Also the Swedish Green party has supported Oceana’s proposal. Most of the Swedish municipalities with coastline to the Sound would like to see the Sound protected. Lately the Swedish responsible authorities have putted the Sound on their agenda, discussing the possibilities in protecting the area. Sweden’s goal of protecting 10 % of its seas by 2020, could affect a protection of the Swedish side of the Sound.
In Denmark the local wish is not as strong as in Swedish, but there is also an increasing interest in protecting it, especially among NGOs, local stakeholders, coastal fishermen and some politicians.
