Developing indices for quality-status classification of marine soft-bottom fauna in Norway

Abstract

As part of the implementation of the EU Water Frame Directive new multimetric indices are developed to assess the quality status based on marine soft-bottom fauna. In this report, several diversity and sensitivity indices were analysed and tested on Norwegian data in order to choose the most suited for inclusion in a multimetric index for Norwegian habitats. The data for the assessements comprised more than 1600 samples from Norwegian fjords and coastal waters. Coefficients to convert species numbers for smaller and larger sampling areas are provided. Correlations between index values and sediment grain size were analysed, accordingly, the indices were normalised to common sediment type prior to fauna classification. Two alternative multimetric indices were suggested: Index 1 = [0.5*(1-AMBI63/7) + 0.5*(SN63/ 2.7)*(N/(N+5)] Index 2 = [0.5*(1-AMBI63/7) + 0.5*(H63/6)] where AMBI is a sensitivity index, SN and H diversity indices, and N the number of individuals in the sample. Both indices can attain values between 0 and 1, where 0 will indicate bad quality status, and 1 will indicate high quality status.