Kattegat

Kattegat

Map of the Kattegat and its catchment area.

The Kattegat forms together with the Danish Straits the transition zone between the North Sea/Skagerrak and the Baltic Sea. The name originates from the Dutch words ‘kat’ (cat) and ‘gat’ (hole, gate). It refers to late medieval navigation jargon, when captains of the Hanseatic trading fleets would compare the Danish Straits to a hole so narrow that even a cat would have difficulty squeezing its way through on account of the many shallow waters and reefs.

The northern boundary of the Kattegat is defined by a line joining Skagen (The Skaw, North Point of Denmark) and Paternoster Skær (57°54′N 11°27′E) and thence North-eastward through the shoals to Tjörn Island. The southern boundary can be defined in several ways, but with DEVOTES, we stick to a definition agreed by Denmark and Sweden and used for the implementation of the EU Marine Strategy Framework Directive (MSFD). Hence, the southern boundary is: (a) a line between Sjællands Odde and Ebeltoft, as well as the sill in the Sound located just south of the Øresund Bridge between Copenhagen and Malmö. In the off-shore parts of the Kattegat, the main islands are Læsø, Anholt and Hesselø. Further, the Kattegat area includes a total of four large fjords: Limfjorden, the largest estuarine complex in Denmark, Mariager Fjord, Randers Fjord and Isefjorden/¬Roskilde Fjord. Along the Swedish coast there are two major embayments, Skälderviken and Laholmsbukten.

The Kattegat is in general well monitored, e.g. via the monitoring programs NOVANA and DCF. In addition, a number of research and development projects have recently generated detailed information on eutrophication status, chemical status, biodiversity status and environmental status as well as human activities and cumulative pressures and impacts.
The environmental status of both open and coastal waters is impaired. Most parts of the Kattegat are affected by eutrophication, which is significant in all coastal waters. Fishing pressures in combination with eutrophication means that biodiversity status in all parts of the Kattegat is impaired. Further, hazardous substances are a problem in all coastal areas and most open areas. For detailed information, please confer with Ærtebjerg et al. (2000), Dahllöf & Andersen (2009), HELCOM (2010) and OSPAR (2010). Recently, the Danish Nature Agency has published an Initial Assessment cf. the MSFD – the characterisation of the Kattegat confirms earlier finding: No parts, neither coastal nor offshore, holds a Good Environmental Status (Naturstyrelsen 2012). The causes of the impaired status in the Kattegat are in general related to inputs of nutrients, destructive fishing practises and pollution with hazardous substances, e.g. heavy metals.In DEVOTES, work will focus on testing and validation of a multi-metric indicator-based tool for assessment of biodiversity. The tool will be developed by the project and the testing made using existing biodiversity indicators in combination with new indicators developed by the project. The validation is planned to be based on the classification of both ‘biodiversity status’ and specific (groups of) indicators vs. ‘impact values’ estimated by the HARMONY project. In the Danish parts, special focus will be put on spatial gradients in ‘biodiversity status’ and well as ‘impact values’ (i.e. the south-northwards gradient).