Prediction of habitats on a fishing bank off Northern Norway using a combination of multivariate analysis and GIS classification

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MAREANO (Marine AREAdatabase for Norwegian coast and sea areas) (www.MAREANO.no) is a multidisciplinary mapping programme, focusing on offshore areas in the southern Barents Sea. It was initiated to address the lack of knowledge about the seabed and environment which is required for informed, sustainable management. The mapping programme includes acquisition of multibeam bathymetry and backscatter data together with a comprehensive, integrated biological and geological sampling programme. Equipment used includes underwater video, box corer, grab, epibenthic-sled, and beam trawl. Mapping outputs from the project include bathymetric data, geological maps (morphology, hard and soft seabed, sediment grain size distribution, sedimentary environment, geological genesis), biological maps (including biodiversity and faunal distribution), and benthic habitat maps. Habitat maps are produced by combining information on landscape features, sediment types, and biological communities. The Tromsøflaket fishing bank was used as a case-study area to develop suitable habitat mapping methods. Multivariate statistical methods were used to relate bottom environment (including multiscale physical descriptors of the seabed derived from multibeam data) and faunal distribution in order to find objective criteria for definition of habitats and biotopes. Prediction of habitat distribution was performed using a supervised GIS classification using physical seabed descriptors for the faunal groups identified by correspondence analysis. The faunistic results from the bottom samples were used to describe the biodiversity of the identified habitats. For future MAREANO cruises an important task will be to ground truth habitat predictions and to test the reliability of these predictions in the wider MAREANO area. The study area is situated on Tromsøflaket fishing bank offshore northern Norway (Fig. 1). This was the first area mapped and sampled under the MAREANO programme in 2005-2006, and provides a good area for testing and development of methodologies. Data for this study comprises two main datasets, multibeam echosounder data and video data. In addition, results from benthic macrofauna samples represent data for description of the general biodiversity of identified habitats. The multibeam data (bathymetry and backscatter) were acquired using a Kongsberg Simrad EM1002 (95 kHz) multibeam system. These data have been processed to produce bathymetry and backscatter raster grids with a cell size of 10 m, which have been converted to ArcGIS format for use in this study