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 habitats in fjords and coastal areas near Tromso, northern Norway, in 1994. The main emphasis was on qualitative samples, but quantitative samples were collected at six sedimentary shore sites. In the quantitative samples, all macrofaunal species (> 1 mm) were recorded. Altogether, 62 polychaete species belonging to 21 families were found. In rocky shore habitats, the most abundant species were the small fan worm Fabricia stellaris, spirorbids, and the 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 coralline algae from exposed shore areas had been excavated by boring Polydora and Dodecaceria. In sandy and muddy shore habitats, species assemblages were dominated by polychaetes, oligochaetes, and bivalves. The most abundant polychaetes were the spionid Pygospio elegans, the orbiniid Scoloplos armiger, capitellids, the lugworm Arenicola marina, and Fabricia stellar is. Species 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 dense mats (> 200 000 ind. m(-2)) on the sediment surface which possibly may be related to organic enrichment.