Polychaetes in intertidal rocky and sedimentary habitats in the region of Tromso, northern Norway

Polychaetes were collected from 10 rocky and 10 sandy and muddy shore habit ats in fjords and coastal areas near Tromso, northern Norway, in 1994. The main emphasis was on qualitative samples, but quantitative samples were col lected at six sedimentary shore sites. In the quantitative samples, all mac rofaunal species (> 1 mm) were recorded. Altogether, 62 polychaete species belonging to 21 families were found. In rocky shore habitats, the most abun dant species were the small fan worm Fabricia stellaris, spirorbids, and th e orbiniid Naineris quadricuspida. In many shore sites, Fabricia tubes and filamentous green and brown algae formed densely interwoven mars, housing a highly diverse fauna of worms, molluscs and insect larvae. Crusts of coral line algae from exposed shore areas had been excavated by boring Polydora a nd Dodecaceria. In sandy and muddy shore habitats, species assemblages were dominated by polychaetes, oligochaetes, and bivalves. The most abundant po lychaetes were the spionid Pygospio elegans, the orbiniid Scoloplos armiger , capitellids, the lugworm Arenicola marina, and Fabricia stellar is. Speci es assemblages on sheltered tidal flats in fjords largely corresponded with the "Macoma community" from the North Sea area, but differed in that there were no nereid polychaetes. Near Tromso, Fabricia and Pygospio formed dens e mats (> 200 000 ind. m(-2)) on the sediment surface which possibly may be related to organic enrichment.