Testing of the sensitivity indices ISI2018 and NSI2018, and a revised species list with sensitivity values for soft sediment fauna
- Year of publication
- 2020
- Involved from NIVA
-
Gunhild Borgersen
- Contributors
- Gunhild Borgersen, Martin Hektoen, Fredrik Melsom, Christiane Todt
Summary
In 2018, NIVA conducted a revision of the sensitivity indices Norwegian Sensitivity Index (NSI) and Indicator Species Index (ISI2012). The audit included calculation of new sensitivity values for the soft bottom species, and new class boundaries for the revised sensitivity indices, which were named NSI2018 and ISI2018. NIVA has, in collaboration with three other laboratories, tested out NSI2018 and ISI2018 by comparing the quality status classification of the revised indices with the classification of the indices used today (NSI2012 and ISI2012). The revised indices NSI2018 and ISI2018 classified fewer stations to good and very good status in all ecoregions except for NSI in the North Sea South and the North Sea North. The differences were greatest for NSI in the Norwegian Sea North and the Barents Sea, and for ISI in the North Sea North and the Norwegian Sea South. In total, ISI2012 and ISI2018 classified 58.4% of the stations to identical status class, and NSI2012 and NSI2018 classified 70.9% of the stations to identical status class. ISI2018 classified 36.7% of the stations to a poorer status class compared to ISI2012, and 4.9% of the stations to a better status class. For NSI, the proportion of stations that classified better and poorer was approximately identical between the 2018 and 2012 versions. Over 90% of the stations was classified to the same status class or only deviated by on one status class for the 2012 and 2018 versions of both indices. NIVA recommends that the revised sensitivity values and indices with associated status class boundaries should replace the existing ones (i.e. ISI2018 and NSI2018 replace respectively ISI2012 and NSI2012). The results indicate that the revised sensitivity indices provide a more accurate measure of the overall sensitivity (or tolerance) of the species assemblage found in a sample since more species have an associated sensitivity value.