Ecological correlates of Arctic Serpulidae (Annelida, Polychaeta) distributions

Polychaetes are traditionally considered poor biogeographic indicators because they tend to show ecological rather than geographic fidelity in their distribution. We analyzed distributions of arctic Serpulidae from ecological and biogeographic perspectives. Habitat associations were studied by principal 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 contained rocks or shells. Temperature and depth are shown to be major environmental factors controlling distributions. Substrate associations differed significantly among studied species and appeared to be determined by sedimentation tolerances of individual species. Bathymetrically, the arctic serpulid fauna mostly consists of lower sublittoral-upper bathyal and lower sublittoral-bathyal species. Clustering by habitat produced four groups: 1) deep- and cold-water species (Protis arctica, Hyalopomatus claparedii); 2) relatively warm-water species associated with hard sediments (Hydroides norvegicus, Serpula vermicularis, and Pomatoceros triqueter); 3) warm-water species associated with soft sediments (Ditrupa); 4) group with the highest habitat 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 with complete absence of Pacific elements. Both distribution ranges and habitat characteristics suggest that the fauna of arctic serpulids is formed by post-glacial Atlantic migrants penetrating into the Arctic with warm Atlantic currents, with the addition of deep-water relicts of the pre-glacial fauna.