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No. 55: Intercalibration of NOVANA soft bottom fauna analysis 2013-2014

Hansen, J. L. S., Josefson, A. B., Lundsteen, S, Norden Andersen, O. G., Fossing, H. & Møller, B. L. 2015: Interkalibrering af NOVANA blødbundsfaunaanalyser 2013-2014. Aarhus Universitet, DCE – Nationalt Center for Miljø og Energi, 31 s. - Teknisk rapport fra DCE - Nationalt Center for Miljø og Energi nr. 55. dce2.au.dk/pub/TR55.pdf

Summary

This report describes the results from a nation-wide intercalibration of soft-bottom fauna samples taken under the national monitoring programme NOVANA. A total of 60 replicate samples were collected from a station in the western Kattegat, sieved and preserved according to the national guidelines for sampling of soft-bottom fauna. The samples were subsequently coded and sent out to eight different consultants who provide taxonomic analyses and report soft-bottom fauna data under the NOVANA programme. Each company received five coded samples in a first round. The results were reported and the samples were returned to The Marine Scientific Data Centre at Aarhus University. The samples were subsequently sent out to a second consultant so that each sample group was analysed by two different consultants. Samples and consultants were kept anonymised throughout the procedure. In general, the results showed significant differences between the consultants with respect to total abundances and species composition. These differences seem to arise from the taxonomic work and because some individuals were overlooked during the sorting of the samples. In some cases, there was only 50 per cent correspondence in species lists obtained from the same samples. The soft-bottom fauna data from the monitoring programme are used to classify the ecological quality by the DKI index. Therefore, the measurements of the ecological quality status are potentially biased by the differences between consultants. However, the indices used to classify the ecological quality, Shannon diversity, AMBI and DKI, were less affected by the “consultant factor” than the other measures such as species richness and species composition, and therefore give a more robust measure of the ecological quality.