Does the analysed size fraction of benthic foraminifera influence the ecological quality status and the interpretation of environmental conditions? Indications from two northern Norwegian fjords

The introduction of the European Water Framework Directive has increased interest in benthic foraminifera as a biomonitoring tool. This prompted need to standardise methods used analyse foraminifera, including which sediment fraction analyse. In some regions produce small (< 125 µm) adult tests, and current study assessed effect analysing > 63 µm or on determining Ecological Quality Status (EcoQS) two fjords northern Norway. diversity indices Shannon-Wiener index (H’log2) Hurlbert’s rarefaction (ES100), multi-metric Norwegian Index (NQI), from both resulted same similar EcoQS, reflecting good environmental conditions fjords. applied AZTI’s Marine Biological (AMBI), except at one location had moderate EcoQS. At this especially, more with tolerant opportunistic response organic matter enrichment occurred than fraction. Hence, higher H’log2 ES100 can be somewhat misleading it indicates better conditions, whereas AMBI input. Stainforthia group Epistominella vitrea, indicating primary productivity were, however, mostly absent Their absence could have consequences for monitoring potential anthropogenic pressure factors identifying long-term changes when using suggests would sufficient EcoQS