Vikkilen 2014. Mapping of habitats and content of pollutants in sediments of shallow waters Year: 2014

Summary

Vikkilen, Grimstad, has been a site for shipbuilding since the 1750s. Today’s activities include a shipyard, engineering industries and a smaller marina. The shipyard AS Nymo has been in operation since 1946, with sand blasting and recoating of hulls as important activities. The sand blasting and recoating activities ended in 2013. In a comprehensive survey of the state of pollution in 2004/2005 and 2008 it was found that the sediments were highly contaminated by PAH and TBT. The main problem in Vikkilen is related to tin organic compounds, especially tributyltin (TBT) in antifouling agents for boats. TBT was also found in high concentrations in the snail, and several snail species have developed severe gender disorders (imposex and intersex). The purpose of the present survey was to identify pollution status in shallow waters (less than 5 meters depth) and mapping habitats like eelgrass meadows and intertidal soft bottom. The results will inform an assessment whether active remediation should be required or avoided. The inner part of Vikkilen has shallow, flat sand- and mud sediments. The shallowest areas will be dry at low tide. The seafloor slopes rapidly down to 10 m depth, with eelgrass growing between 1 - 5 meters. The eelgrass meadows are relatively small, but in good condition. The intertidal soft bottom areas and eelgrass meadows are two locally important habitats in Vikkilen. The area seems relatively species-rich compared to what one might expect from the activities and pollution level in the area.