Ecological correlates of arctic Serpulidae (Annelida, Polychaeta) distributions

Polychaetes are traditionally considered poor biogeographic indicators beca use they tend to show ecological rather than geographic fidelity in their d istribution. We analyzed distributions of arctic Serpulidae from ecological and biogeographic perspectives. Habitat associations were studied by princ ipal component, correspondence, cluster, and discriminant function analyses . Records for each site included depth, temperature, salinity and sediment type, with particle size analysis and notes of whether the sample also cont ained rocks or shells. Temperature and depth are shown to be major environm ental factors controlling distributions. Substrate associations differed si gnificantly among studied species and appeared to be determined by sediment ation tolerances of individual species. Bathymetrically, the arctic serpuli d fauna mostly consists of lower sublittoral-upper bathyal and lower sublit toral-bathyal species. Clustering by habitat produced four groups: 1) deep- and cold-water species (Protis arctica, Hyalopomatus claparedii); 2) relat ively warm-water species associated with hard sediments (Hydroides norvegic us, Serpula vermicularis, and Pomatoceros triqueter); 3) warm-water species associated with soft sediments (Ditrupa); 4) group with the highest habita t variability, associated to a larger degree with soft sediments (Filograna implexa, Placostegus tridentatus, Protula globifera and Protula tubularia) . The fauna of arctic serpulids consists of North-Atlantic boreal forms wit h complete absence of Pacific elements. Both distribution ranges and habita t characteristics suggest that the fauna of arctic serpulids is formed by p ost-glacial Atlantic migrants penetrating into the Arctic with warm Atlanti c currents, with the addition of deep-water relicts of the pre-glacial faun a.