Nature Index of Norway: Further development of soft sediment indicators of coastal water

Summary

This report is made on commission for the Directorate for Nature Management (DN). By statistical analyses and Geographic Information Systems (GIS), we show here a method for production of area representative maps of reference values for various indices. This we consider as a great improvement over earlier deliveries in which the same reference value was used in all regions, counties and municipalities in Norway, and we suggest that the results from this project may be included in the next delivery to the nature of the index. Through the Norwegian Coastal Monitoring Programme (1990-2010) and other projects, NIVA have available data with high spatial and temporal coverage from a period of more than 30 years. Five different indices are estimated based on these data: Shannon-Wiener diversity index (H '), species richness (ES100), Indicator Species Index (ISI) and the Norwegian Quality Index 1 and 2 (NQI1 and NQI2). The data is specified to ecoregion (Skagerrak, North Sea, Norwegian Sea, and Barents Sea) and important geophysical predictor variables: depth, slope, wave exposure, terrain-, and basin structures) in GIS. We considered the models as being relatively good, but could with advantage also have been evaluated qualitatively by persons with local knowledge. A possible improvement of the models could be a further differentiation between different types of water bodies as well as including other relevant explanatory variables (e.g. a current speed model). On the basis of the work we have done in this project, we strongly recommend using the same or similar methodology for preparation of reference values with full geographic and habitat-specific representation, where adequate data exists.