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Mapping marine habitats in Kattegat


This pratical information set shows the mapping and modelling of habitats in the Kattegat

Application in MSP:
Type of Issue:
Type of practice:
Stage of MSP cycle:
Cross-border / trans-national aspect:
Coherence with other processes:
Key words:

Questions this practice may help answer

  • What technologies and methods can be used for seabed habitat mapping?
  • What have been the results and recommendations for Nature2000 areas of the seabed mapping in the Kattegat area of the Baltic Sea?

Implementation Context

The quality of seabed habitat mapping on deeper waters was previously governed by the number of samples taken, their spatial coverage and density as well as the limitation of the available technology. New technologies such as multibeam sonar and high-resolution sidescan sonar available today enable us to construct detailed images of the sea floor in a considerably shorter period and to discriminate objects on the sea floor of decimetre size.  The new acoustic mapping technologies combined with predictive models describing important key biological elements have a wide range of applicability for the management of offshore resources as it has been demonstrated in the present case study.

Aspects / Objectives

To map benthic habitats on hard substrate in selected case study areas within BALANCE pilot area 1 in Kattegat.


  • Different geophysical remote sensing instruments were deployed in the acoustic mapping
  • A part suite of standard methods and procedures was followed in collating biological and sediment samples that range from core sampling to diver’s observations and video footage.
  • Additional data sets were acquired from different sources for the area of interest.
  • Subsequently, the fieldwork results were applied to the modelling of key biological elements and hard bottom habitats as well as to the preparation of seabed habitat maps.

Main Outputs / Results

The investigation show that key biological elements like cover of total erect macro algal vegetation and cumulative erect macro algal vegetation can be modelled and extrapolated successfully to other areas on a local scale.

The utilisation of acoustic data is a strong tool for the broadscale characterisation of benthic habitats. The technology of remote sensing is developing fast and systems with high resolution is being developed, also software for data cleaning and interpretation is getting very advanced and complex.

Overall this study confirms that the reefs Kim’s Top, Den Kinesiske Mur, Groves Flak and surrounding areas all form outstanding coherent reef structures in inner Danish waters. Based on the present findings of new spectacular reef features the report recommended to enlarge the Danish Nature-2000 area around Kim’s Top to include the surrounding reefs.


The practice shows the application of new technologies to construct detailed images of the sea floor in a specific area. The technologies available during the study in 2007 are mostly out-dated by new technologies. However, the methodology of seabed habitat mapping used in this practice can be used in mapping other sea beds in other regions.

Costs / Funding Source

Interreg IIIB Baltic Sea Region

Responsible entities and contact persons

  • Karsten Dahl, ​Department of Bioscience - Marine Diversity and Experimental Ecology. Frederiksborgvej 399. building B1.04. 4000 Roskilde. Denmark, Phone: +4587158566, e-mail (kda[at]bios[dot]au[dot]dk)
  • Jørgen O. Leth, The Geological Survey of Denmark and Greenland
  • Zyad Al-Hamdani, The Geological Survey of Denmark and Greenland
  • Jacob Carstensen, The National Environmental Research Institute
  • Steffen Lundsteen, The National Environmental Research Institute
  • Dennis Anthony, The Royal Danish Administration Navigation and Hydrography